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1
Kijovský, František. "Fotovoltaický on-grid systém s akumulací". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219414.
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This thesis deals with processing the current issue of trends in on-grid photovoltaic system with accumulation. It examines the posibility of accumulation of photovoltaic systems, analyzing their strengths and weaknesses in the practical deployment. It compares the different storage technologies based on indicators of cycles, durability and price ranges. The practical part deals with the technical design of hybrid power system and then comparing with the standard on-grid system in technical and economical point of view.
2
Abeyasekera, Tusitha Darshana. "Improvements to grid connected photovoltaic inverters". Thesis, University of Newcastle Upon Tyne, 2005. http://hdl.handle.net/10443/585.
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This thesis presents investigations into issues of power quality and reliability of grid connected inverters and proposes improved topological and control solutions to improve performance and cost effectiveness of these systems. Synchronisation of inverters to the grid can be problematic in its operational reliability. Of all grid synchronisation techniques phase locked loop based method offers a simple, robust and flexible solution. However the conventional PLL approach is inherently difficult to tune, due to the influence of its parameters on loop dynamics, filtering properties and output waveform spectral purity. The improved PLL proposed in the thesis, relieves the tuning task by decoupling the effect of its loop parameters from performance characteristics. Inverter power quality issues are addressed beginning from sources of harmonic distortion, classified as intrinsic and extrinsic. A potential intrinsic source is a look-up table generated reference sinusoid accessed in non-uniform increments resulting in harmonic, inter-harmonic or subharmonic distortion. The effect is studied in detail with analytical derivations and experimental results. On the other hand, extrinsic distortions are mainly caused by the distorted grid voltage. The effect of inductor current feedback, output current feedback and capacitor current feedforward on harmonic impedance is studied. The combination of inductor current feedback and capacitor current feedforward demonstrates good disturbance rejection and damped load transient performance on a low power grid connected inverter. It is shown that by carefully selecting the feedforward coefficient, the structure of the control system could be varied between the feedback and feedforward schemes. Theoretical concepts are validated on a purpose built 50OW 3-level grid connected inverter controlled through a generalised controller board based on TMS320C31 DSP. Multi-level inverters are presented as a favourable topological alternative to H-bridge grid connected inverters at medium and high power levels. The effect of number of levels, topology and switching strategy on switching losses, spectral performance and cost is analysed. Simulation results reveal that Boolean manipulation of PWM signals can be used to re-distribute harmonic energy for common mode cancellation, resulting in low switching harmonic amplitudes. Such a scheme - Carrier anti-phase sine (CAS) PWM is proposed and used in the prototype 3-level inverter.
3
Massawe, Henry Benedict. "Grid Connected Photovoltaic Systems with SmartGrid functionality". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22861.
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SummaryThis master?s thesis is focused on the design of grid connected PV power stage inverter. This inverter will be used for solar power application in the renewable energy laboratory at NTNU. The designed power stage inverter is a single phased 1kW, 230 V at the output. The DC/AC power stage converter is able to convert the minimum available voltage at the PV array of about 100V DC. The grid connected PV power stage inverter is designed in Multism and implemented in NI labView for simulation and analysis of output voltage and current.To achieve this goal, several literatures will be studied related to the work in this thesis. The choice of the best circuitry topology must be made and important parameters for the power stage inverter should be calculated/estimated. The control strategy for the power stage inverter shall be proposed and the expected desired output shall be analyzed in LabView and compared to the standard one (Grid output).Problem DescriptionAt NTNU a laboratory for renewable energy is under construction. This lab emulates several different renewable energy sources connected together. The power from the PV panels mounted outside on the building will be available for connection in the laboratory. A survey of control structures for the inverter when used as a grid connected PV inverter will be made. Based on this a suitable control will be chosen, which will include methods for grid synchronization, maximum power utilization, anti-islanding and current/voltage control. System models must be developed, which shall form a basis for controller parameter estimation. In the project the instrumentation system for collection of operation information of the PV plant into a database will be designed based on EtherCAT network. The purpose of this database is to collect and archive performance, reliability and operating cost data for this PV based distributed power systems.This thesis focused on the design of the single phase converter power stage. Important parameters for the inverter stage will be proposed. The converter is designed in Multism and implemented in LabView for the control of the output and user interface. The remaining task to accomplish the whole NTNU project in this laboratory will be the proposal of the control system.
4
Ropp, Michael Eugene. "Design issues for grid-connected photovoltaic systems". Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/13456.
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Chapes, Stephen. "Non-traditional photovoltaic products and grid interactive design". Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/918.
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Armstrong, Matthew. "Power quality improvement of grid connected photovoltaic inverters". Thesis, University of Newcastle Upon Tyne, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512180.
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Mansouri, Seyed Akbar. "Circuit Topology Study of Grid-Connected Photovoltaic System". The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1308328627.
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Cormode, Daniel. "Large and Small Photovoltaic Powerplants". Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/556469.
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The installed base of photovoltaic power plants in the United States has roughly doubled every 1 to 2 years between 2008 and 2015. The primary economic drivers of this are government mandates for renewable power, falling prices for all PV system components, 3rd party ownership models, and a generous tariff scheme known as net-metering. Other drivers include a desire for decreasing the environmental impact of electricity generation and a desire for some degree of independence from the local electric utility. The result is that in coming years, PV power will move from being a minor niche to a mainstream source of energy. As additional PV power comes online this will create challenges for the electric grid operators. We examine some problems related to large scale adoption of PV power in the United States. We do this by first discussing questions of reliability and efficiency at the PV system level. We measure the output of a fleet of small PV systems installed at Tucson Electric Power, and we characterize the degradation of those PV systems over several years. We develop methods to predict energy output from PV systems and quantify the impact of negatives such as partial shading, inverter inefficiency and malfunction of bypass diodes. Later we characterize the variability from large PV systems, including fleets of geographically diverse utility scale power plants. We also consider the power and energy requirements needed to smooth those systems, both from the perspective of an individual system and as a fleet. Finally we report on experiments from a utility scale PV plus battery hybrid system deployed near Tucson, Arizona where we characterize the ability of this system to produce smoothly ramping power as well as production of ancillary energy services such as frequency response.
9
Rye, Rebecca Pilar. "Design and Evaluation of a Photovoltaic Inverter with Grid-Tracking and Grid-Forming Controls". Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/97398.
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This thesis applies the concept of a virtual-synchronous-machine- (VSM-) based control to a conventional 250-kW utility-scale photovoltaic (PV) inverter. VSM is a recently-developed control scheme which offers an alternative grid-synchronization method to the conventional grid-tracking control scheme, which is based on the dq phase-locked-loop- (PLL-) oriented vector control. Synchronous machines inherently synchronize to the grid and largely partake in the stabilization of the grid frequency during power system dynamics. The purpose of this thesis is primarily to present the design of a grid-forming control scheme based on the VSM and the derivation of the terminal dq-frame ac impedance of the small-signal model of the inverter and control scheme. This design is also compared to the design of the conventional grid-tracking control structure, both from a loop design and terminal dq-frame ac impedance standpoint. Due to the inherent lax power-balance synchronization, the grid-forming control scheme results in 1 to 2 decades' lower frequency range of negative incremental input impedance in the diagonal elements, which is a favorable condition for stability. Additionally, the stability of the grid-forming control scheme is compared to the conventional grid-tracking control using the generalized Nyquist criterion (GNC) for stability under three modes of operation of active and reactive power injection. It is found that the connection is stable for both control schemes under unity power factor and fixed reactive power modes; however, the grid-forming control is able to inject twice the amount of active power under the voltage regulation mode when compared to the grid-tracking control.Master of Science
Concerns about the current and future state of the environment has prompted government and non-profit agencies to enact regulatory legislation on fossil fuel emissions. In 2017, electricity generation comprised 28% of total U.S. greenhouse gas emissions with 68% of this generation being due to coal combustion sources. As a result, utilities have retired a number of coal power plants and have employed alternative means of power generation, specifically renewable energy sources (RES). Most RES operate as variable-frequency ac sources (wind) or dc sources (solar) and are interfaced with the power grid through ac-dc-ac or dc-ac converters, respectively, which are power-electronic devices used to control the injection of power to the grid. Conventional converters synchronize with the grid by tracking the phase of the voltage at the point of common coupling (PCC) through a phase-locked loop (PLL). While power system dynamics significantly affect the performance of a PLL, and, subsequently, inverters' operation, the initial frequency regulation during grid events is attributed to the system's inherent inertia due to the multitude of synchronous machines (SM). However, with the steady increase of RES penetration, even while retaining the number of SM units, the net inertia in the system will decrease, thus resulting in prolonged responses in frequency regulation to the aforementioned dynamics. This thesis investigates the control of variable-frequency sources as conventional synchronous machines and provides a detailed design procedure of this control structure for photovoltaic (PV) inverter applications. Additionally, the stability of the connection of the inverter to the grid is analyzed using innovative stability analysis techniques which treat the inverter and control as a black box. In this manner, the inner-workings of the inverter need not be known, especially since it is proprietary information of the manufacturer, and the operator can measure the output response of the device to some input signal. In this work, it is found that the connection between the inverter and grid is stable with this new control scheme and comparable to conventional control structures. Additionally, the control based on synchronous machine characteristics shows improved stability for voltage and frequency regulation, which is key to maintaining a stable grid.
10
Prichard, Martin Edward. "SINGLE PHASE MULTILEVEL INVERTER FOR GRID-TIED PHOTOVOLTAIC SYSTEMS". UKnowledge, 2015. http://uknowledge.uky.edu/ece_etds/81.
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Multilevel inverters offer many well-known advantages for use in high-voltage and high-power applications, but they are also well suited for low-power applications. A single phase inverter is developed in this paper to deliver power from a residential-scale system of Photovoltaic panels to the utility grid. The single-stage inverter implements a novel control technique for the reversing voltage topology to produce a stepped output waveform. This approach increases the granularity of control over the PV systems, modularizing key components of the inverter and allowing the inverter to extract the maximum power from the systems. The adaptive controller minimizes harmonic distortion in its output and controls the level of reactive power injected to the grid. A computer model of the controller is designed and tested in the MATLAB program Simulink to assess the performance of the controller. To validate the results, the performance of the proposed inverter is compared to that of a comparable voltage-sourced inverter.
11
Straka, Michal. "Využití fotovoltaických systémů v Off-grid aplikacích". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219396.
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This masters thesis deals with the use of off-grid photovoltaic systems. First we explain the problems associated with the power and energy potential of photovoltaic system components, design of photovoltaic systems for autonomous operation and the financial evaluation. The result of the masters thesis is to create an application used to design the island system in the whole output range (the smallest power systems to house systems application). The conclusion of the masters thesis is devoted to designing three type of projects from our application – a garden cottage, a family cottage and the house.
12
Mnider, Abdalbaset Mohamed Husian. "Power quality improvements of single-phase grid-connected photovoltaic systems". Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3967.
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The number of distributed power generation systems (DPGSs), mostly based on photovoltaic (PV) energy sources is increasing exponentially. These systems must conform to grid codes to ensure appropriate power quality and to contribute to grid stability. A robust and reliable synchronization to the grid is an important consideration in such systems. This is due to the fact that, fast and accurate detection of the grid voltage parameters is essential in order to implement stable control strategies under a broad range of grid conditions. The second-order generalized integrator (SOGI) based phase-locked loop (PLL) is widely used for grid synchronization of single-phase power converters. This is because it offers a simple, robust and flexible solution for grid synchronization. However, the SOGI-PLL is affected by the presence of a dc offset in the measured grid voltage. This dc voltage offset is typically introduced by the measurements and data conversion process, and causes fundamental-frequency ripple in the estimated parameters of the grid voltage (i.e. voltage amplitude, phase angle and frequency). In addition to this ripple, the unit amplitude sine and cosine signals of the estimated phase angle (i.e. unit vectors), that are used to generate reference signals in the closed-loop control of grid-connected PV converters will contain dc offset. This is highly undesirable since it can cause dc current injection to the grid, and as a consequence, the quality of the power provided by the DPGSs can be degraded. To overcome this drawback, a modified SOGI-PLL with dc offset rejection capability is proposed. The steady-state, transient and harmonic attenuation performance of the proposed PLL scheme are validated through simulation and experimental tests. The overall performance demonstrates the capability of the proposed PLL to fully reject such dc current injection as well as to provide a superior harmonic attenuation when compared with the SOGIPLL and two other existing offset rejection approaches. It is shown that, the proposed PLL scheme can enhance the overall total harmonic distortion (THD%) of the injected power by 15% when compared to the conventional SOGI-PLL. In addition to the synchronization, grid-connected PV systems require a current control scheme to regulate the output current. Due to the simple implementation, proportional-integral (PI) controllers in the stationary reference frame are commonly used for current controlled inverters. However, these PI-controllers exhibit a major drawback of failure to track a sinusoidal reference Abstract ii without steady-state error, which may result in low-order harmonics. This drawback can be overcome if the PI-controllers are implemented in direct-quadrature (dq) rotating reference frame. In single-phase systems, the common approach is to create a synthesized phase signal orthogonal to the fundamental of the real single-phase system so as to obtain dc quantities by means of a stationary-to-rotating reference frame. The orthogonal synthesized signal in conventional approaches is obtained by phase shifting the real signal by a quarter of the fundamental period. The introduction of such delay in the system deteriorates the dynamic response, which becomes slower and oscillatory. This thesis proposes an alternative way of implementing such PI-controllers in the dq reference frame without the need of creating such orthogonal signals. The proposed approach, effectively improves the poor dynamic of the conventional approaches while not adding excessive complexity to the controller structure. The results show that, in addition to its ability to regulate the current and achieve zero steady-state error, the proposed approach shows superior dynamic response when compared with that of conventional delay-based approach.
13
Malek, Hadi. "Control of Grid-Connected Photovoltaic Systems Using Fractional Order Operators". DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/2157.
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This work presents a new control strategy using fractional order operators in threephase grid-connected photovoltaic generation systems with unity power factor for any situation of solar radiation. The modeling of the space vector pulse width modulation inverter and fractional order control strategy using Park’s transformation are proposed. The system is able to compensate harmonic components and reactive power generated by the loads connected to the system. A fractional order extremum seeking control and “Bode’s ideal cut-off extremum seeking control” are proposed to control the power between the grid and photovoltaic system, to achieve the maximum power point operation. Simulation results are presented to validate the proposed methodology for grid-connected photovoltaic generation systems. The simulation results and theoretical analysis indicate that the proposed control strategy improves the efficiency of the system by reducing the total harmonic distortion of the injected current to the grid and increases the robustness of the system against uncertainties. Additionally, the proposed maximum power point tracking algorithms provide more robustness and faster convergence under environmental variations than other maximum power point trackers.
14
Wang, Zhongkui. "Reactive Power Control and Optimization of Large Scale Grid Connected Photovoltaic Systems in the Smart Grid". The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1388764166.
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Secchi, Mattia. "The Role of Photovoltaic Generation and Electric Mobility in Future Distribution Systems". Doctoral thesis, Università degli studi di Trento, 2022. https://hdl.handle.net/11572/354867.
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In order to meet the worldwide limits on greenhouse gases emissions, a shift from a fossil fuels to a renewable energy-based electric system is required. As this process goes on, both the power generation and consumption profiles are changing in daily pattern and magnitude, so the power grid needs to become more and more flexible in order to handle this variability.
At the distribution level, photo-voltaic (PV) systems are, by far, the most widespread distributed energy resource, mostly due to the recent drop in the cost at the residential level. As more and more consumers become also producers (the so called "prosumers") and the volatile solar energy production increases, a higher number of storage systems is required to both avoid grid destabilisation and minimise the CO$_2$ emissions.
At the same time, since the transportation sector is responsible for a sizeable part of the total CO$_2$ emissions, electric vehicles (EVs) are bound to replace traditional internal combustion engine vehicles. However, two main issues may arise when a large number of vehicles are connected to the existing power grid at the same time.
The first issue is that the electricity required to charge them needs to be renewable, while the second is that, a rapid electrification of the existing vehicles fleet could destabilise the grid.
In this context, this thesis aims at partially addressing these two issues by analysing different ways to reduce the impact of both PV systems and EVs on low (LV) and medium (MV) voltage grids.
After the introduction and a chapter dealing with the most closely related research work, a novel optimisation algorithm, aimed at obtaining the optimal storage capacity for each prosumer belonging to a "renewable energy community" is presented. The algorithm minimises the dependence of the community on the main grid, which is one of the main purposes of this new model, while minimising the total installed storage capacity. The algorithm is tailored to the specific case study, because it keeps track of the willingness of the users to install a battery and keeps the voltage levels between regulatory limits in the optimisation process.
In the second part instead, the effects of "uncontrolled" and "smart" EV-charging the electric vehicles with the aim of reducing the power fluctuations at the MV/LV transformer level are analysed. In particular, the interaction between PV production and EV charging is investigated, while considering the grid voltage fluctuations, the distribution line losses and the transformer loading levels at the same time. The broader impact of smart charging is also analysed by performing a simplified economic and battery wear analysis.
Results help in understanding if storage devices can reduce the dependence of a renewable energy community on the main grid, and to what extent it is possible and economically viable to do so. Moreover, results quantify a realistic range of EV and PV system penetration in a LV grid that still allows for a combined minimisation of their impact on the power grid.
16
Kobayakawa, Toru. "Assessment and evaluation of a photovoltaic micro-grid in Sundarbans, India for designing integrated rural electricity systems". Thesis, IIT Delhi, 2016. http://localhost:8080/xmlui/handle/12345678/6983.
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Amirineni, Sai Sree Teja. "Integral Terminal Sliding Mode Control Design for Grid-connected Photovoltaic Systems". Thesis, University of Louisiana at Lafayette, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10683070.
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This thesis designs a Fuzzy- based Integral Terminal Sliding Mode (FITSMC) control scheme for the MPPT and VSI of a PV array connected the grid. The proposed approach aims at ensuring that the output voltage is in track with the reference voltage generated by the perturb and observe algorithm. This latter ensures maximum power production for the PV system. The proposed FITSMC eliminates the voltage drag and keeps the output voltage of the MPPT control in track with the reference voltage in a relatively brief time. Its implementation to the VSI control ensures the mitigation of deep voltage sags that arise due to high fluctuations in the load. The performance of the proposed approach is assessed using the SPR-305E-WHT-D PV array structure and further compared to that of a standard SMC. Based on the obtained results, we can assess that the proposed FITSMC ensures finite time convergence of the error to zero and proper mitigation of disturbances and grid faults.
18
Shen, Ming. "Distributed Solar Photovoltaic Grid Integration System : A Case Study for Performance". PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/945.
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The needs to the sustainable development of electricity, energy efficiency improvement, and environment pollution reduction have favored the development of distributed generation (DG). But the problems come with increasing DG penetration in distribution networks. This thesis presents the Solar Energy Grid Integration System (SEGIS) Stage III project done by Portland General Electric (PGE), Advanced Energy, Sandia National Lab on a PGE selected distribution feeder. The feeder has six monitored commercial solar PV systems connected. The total power output from the PV systems has the potential to reach 30% of the feeder load. The author analyzes the performance of the solar feeder on both generation and voltage effects. As a project report, it introduced a new islanding detection done by other team members to give an islanding solution of future high penetration distribution networks. At last, the author describes micro-grid and grid support concepts in a SEGIS concept paper with some examples.
19
CORONA, FABIO. "Building Integrated Photovoltaic Systems: specific non-idealities from solar cell to grid". Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2538891.
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After an initial phase of great diffusion of large Photovoltaic (PV) systems installed on the ground, the recent evolution of the feed-in tariffs makes the Building
Integrated PV (BIPV) systems for residential, commercial and industrial users, the more befitting application of the PV technology.
Unfortunately, the building integration implies some critical issues on the operation of principal components, such as the PV panels or the grid-connected inverter, typical of this kind of installation and not so important in the case of ground mounted PV plants. These non-idealities can be due to: presence of obstacles near the PV panels, like trees, poles, antennas, architectural elements (chimneys, barriers, buildings in the neighbourhood); non-optimal orientation of the PV field (not Southward) or with different orientations among the sub-fields,
with consequent production asymmetry between morning and evening or mismatch; sub-optimal tilt angle of the PV modules, as it is fixed by the building roof; not-efficient cooling of the PV panels, which can cause temperature gradients both horizontally, between PV modules in the central area of the field and the peripheral ones, and vertically, between panels installed in the bottom and in the top of a structure, due to the direction of the cooler flow.
The consequences of these non-idealities is the subject of this PhD dissertation, from both theoretical, through convenient simulation tools, and experimental viewpoints. The most evident of these effects is the mismatch of the currentvoltage characteristics of the PV field panels. With the aim of illustrating the analysis methodologies used to study the mismatch effect on all the PV system components, a specific case study is considered, constituted by a large BIPV system (almost 1MWp) installed on the roof of a wholesale warehouse.
20
Al-Omari, Ali Hussein Abduljabbar. "Contributions to converters in single phase distributed photovoltaic systems". Thesis, University of Plymouth, 2018. http://hdl.handle.net/10026.1/11159.
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This thesis contributes to improve the photovoltaic Distributed Generation (DG) systems by proposing three novel methods to the system. On DC conversion side, a new integrated magnetic structure for interleaved converter and a new method to calculate the eddy current and hysteresis losses in the magnetic core were proposed. On inversion side, A new synchronisation method for grid tie inverters was suggested. The technique is using the Recursive Discrete Fourier Transform (RDFT) to find fundamental in grid waveform. On the DC converter side, the benefits of the new structure is to produce magnetic flux that alternate in the core across both directions of the BH curve. The advantages of alternating magnetic flux are, to increase the Root Mean Square (RMS) value of produced current with respect to core volume that lead to reduce the core size and reducing losses by using high permeability material. Furthermore, the proposed structure led to reduce the number of magnetic components which helped to improve the efficiency. The converter was tested and evaluated were the results show that the topology is able to produce high gain and it shows that the new interleaved structure is efficient. A new method to calculate the eddy current loss was proposed, where the flux waveform in the core was analysed to its original frequency component. Each of the components were utilized individually to find the loss. The effect of changing the duty cycle of the converter was taken into consideration on the total eddy current loss, as it will effect on the total harmonics content in the flux waveform. On the inverter side, due to recent developments combined with the increasing power demand by single phase non-linear loads where voltage spikes, harmonics and DC component were impacted the electric grid quality. These effects can likewise make the synchronisation process a challenge, where filters or Digital Signal processing (DSP) analysers are required to acquire the fundamental component as a consequence to the waveform deformation. A new linear approximation with RDFT is presented in this thesis for grid tie inverters. The new method provides a computation reduction as well as high accuracy in tracking the fundamental frequency in a distorted grid during synchronisation. The method accuracy was proved mathematically and simulated with different input signals. Error in magnitude and frequency measurement were measured, presented and compared with other research in order to verify the proposed method.
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Hara, Nathan. "Monitoring and Data-Logging for Stand-Alone and Grid-Tied Photovoltaic Systems". DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/990.
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This thesis presents the topic of various monitoring and data-logging tools for stand-alone and grid-tied photovoltaic systems. The first part of this report describes the research, testing, and installation of a monitoring system for a stand-alone photovoltaic system created by students of California Polytechnic State University at San Luis Obispo for the 2005 Solar Decathlon. Analysis of the real-time data of the Solar Decathlon House resulted in the discovery of issues within the software of the monitoring system and within the battery bank of the photovoltaic system. The second part of this report gives a detailed description of possible monitoring systems for three different types of grid-tied photovoltaic systems that a possible upcoming project by Cal Poly students could use. System analysis, component analysis, and cost analysis are provided for each proposed grid-tied system. It is concluded that a monitoring system can be chosen only after the full design of the grid-tied system because of the various advantages and disadvantages of each type of photovoltaic system.
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Omole, Adedamola. "Voltage Stability Impact of Grid-Tied Photovoltaic Systems Utilizing Dynamic Reactive Power Control". Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3615.
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Photovoltaic (PV) DGs can be optimized to provide reactive power support to the grid,
although this feature is currently rarely utilized as most DG systems are designed to
operate with unity power factor and supply real power only to the grid. In this work, the
voltage stability of a power system embedded with PV DG is examined in the context of
the high reactive power requirement after a voltage sag or fault. A real-time dynamic
multi-function power controller that enables renewable source PV DGs to provide the
reactive power support necessary to maintain the voltage stability of the microgrid, and
consequently, the wider power system is proposed.
The loadability limit necessary to maintain the voltage stability of an interconnected
microgrid is determined by using bifurcation analysis to test for the singularity of the
network Jacobian and load differential equations with and without the contribution of
the DG. The maximum and minimum real and reactive power support permissible from
the DG is obtained from the loadability limit and used as the limiting factors in
controlling the real and reactive power contribution from the PV source. The designed
controller regulates the voltage output based on instantaneous power theory at the
point-of-common coupling (PCC) while the reactive power supply is controlled by means
of the power factor and reactive current droop method. The control method is
implemented in a modified IEEE 13-bus test feeder system using PSCAD® power system
analysis software and is applied to the model of a Tampa Electric® PV installation at
Lowry Park Zoo in Tampa, FL.
This dissertation accomplishes the systematic analysis of the voltage impact of a PV DGembedded
power distribution system. The method employed in this work bases the
contribution of the PV resource on the voltage stability margins of the microgrid rather
than the commonly used loss-of-load probability (LOLP) and effective load-carrying
capability (ELCC) measures. The results of the proposed method show good
improvement in the before-, during-, and post-start voltage levels at the motor
terminals. The voltage stability margin approach provides the utility a more useful
measure in sizing and locating PV resources to support the overall power system
stability in an emerging smart grid.
23
Chisenga, Lesley. "Development of a low power photovoltaic inverter for connection to the utility grid". Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611257.
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Luthander, Rasmus. "Improved Self-Consumption of Photovoltaic Electricity in Buildings : Storage, Curtailment and Grid Simulations". Licentiate thesis, Uppsala universitet, Fasta tillståndets fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-284091.
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The global market for photovoltaics (PV) has increased rapidly: during 2014, 44 times more was installed than in 2004, partly due to a price reduction of 60-70% during the same time period. Economic support schemes that were needed to make PV competitive on the electricity market have gradually decreased and self-consumption of PV electricity is becoming more interesting internationally from an economic perspective. This licentiate thesis investigates self-consumption of residential PV electricity and how more PV power can be allowed in and injected into a distribution grid. A model was developed for PV panels in various orientations and showed a better relative load matching with east-west-oriented compared to south-oriented PV panels. However, the yearly electricity production for the east-west-system decreased, which resulted in less self-consumed electricity. Alternatives for self-consumption of PV electricity and reduced feed-in power in a community of detached houses were investigated. The self-consumption increased more with shared batteries than with individual batteries with identical total storage capacity. A 50% reduction in feed-in power leads to losses below 10% due to PV power curtailment. Methodologies for overvoltage prevention in a distribution grid with a high share of PV power production were developed. Simulations with a case with 42% of the yearly electricity demand from PV showed promising results for preventing overvoltage using centralized battery storage and PV power curtailment. These results show potential for increasing the self-consumption of residential PV electricity with storage and to reduce stress on a distribution grid with storage and power curtailment. Increased self-consumption with storage is however not profitable in Sweden today, and 42% of the electricity from PV is far more than the actual contribution of 0.06% to the total electricity production in Sweden in 2014.
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Rahimi, Kaveh. "Overcoming Voltage Issues Associated with Integration of Photovoltaic Resources in the Electric Grid". Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/99916.
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Power generation from solar energy has significantly increased, and the growth is projected to continue in the foreseeable future. The main challenge of dealing with solar energy is its intermittent nature. The received irradiation energy of the sun on the earth's surface can fluctuate in a matter of seconds and cause voltage issues to power systems. Considering the high growth rate of solar photovoltaic (PV) resources, it is essential to be prepared to encounter and manage their high penetration levels.
Currently, simplified approaches are used to model the impacts of cloud shadows on power systems. Using outdated standards also limits the penetration levels more than required. Approximately 40% of the new PV installations are residential, or installed at a low voltage level. Currently, all components between utility distribution transformers and customers/loads are either ignored or modeled with oversimplification. Furthermore, large PV systems require a considerable amount of land. However, point sensor models are currently used to simulate those systems. With a point model, the irradiance values measured at a point sensor are used to represent the output of a large PV system. However, in reality, clouds cover photovoltaic resources gradually and if the solar arrays are widespread over a large geospatial area, it takes some time for clouds to pass over the solar arrays. Finally, before 2014, participation of small-scale renewable resources was not allowed in controlling voltage. However, they can contribute significantly in voltage regulation. The main objective of this dissertation is to address the abovementioned issues in order to increase the penetration levels as well as precisely identify and locate voltage problems.
A time-series analysis approach is used in modeling cloud motion. Using the time-series approach, changes of the received irradiation energy of the sun due to cloud shadows are simulated realistically with a Cloud Motion Simulator. Moreover, the use of the time-series approach allows implementation of new grid codes and standards, which is not possible using the old step change methods of simulating cloud impacts. Furthermore, all electrical components between utility transformers and customers are modeled to eliminate the inaccuracy due to using oversimplified models. Distributed PV models are also developed and used to represent large photovoltaic systems. In addition, the effectiveness of more distributed voltage control schemes compared to the traditional voltage control configurations is investigated. Inverters connect renewable energy resources to the power grid and they may use different control strategies to control voltage. Different control strategies are also compared with the current practice to investigate voltage control performance under irradiation variations.
This dissertation presents a comprehensive approach to study impacts of solar PV resources. Moreover, simulation results show that by using time-series analysis and new grid codes, as well as employing distributed PV models, penetration of solar PV resources can increase significantly with no unacceptable voltage effects. It is also demonstrated that detailed secondary models are required to accurately identify locations with voltage problems.PHD
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Muller, Donovan Herbert. "The use of small photovoltaic systems for the electrification of off-grid homes". Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/21862.
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This thesis presents a study of the technical, economic and social appropriateness of small stand-alone photovoltaic (PV) systems for meeting minimal electrical requirements in low-income off-grid households. A comprehensive review of the literature on photovoltaic technology was undertaken to identify key theoretical parameters and issues, and also to determine what the experience has been of similar applications in third world countries. Two PV systems were installed as demonstration projects: one at Uitsig near Cape Town, and the other at Omdraaisvlei in the Northern Cape. In order to monitor and evaluate the techriical performance of these systems, remote data capture units were installed for measuring appropriate parameters for analysis on typical daily, weekly and monthly bases. The degree of matching between the PV output characteristics and the battery and load demand was examined as weLl as the costs of system and component efficiencies under different operating conditions. The economic evaluation aimed to compare small PV systems with these of alternative power systems, for example petrol generators. Using a life cycle costing methodology (discounted to present value) the least-cost option for small power systems was determined under a range of financial scenarios. The social evaluation aimed at determining the impact of PV power on peoples' lifestyles. The results of the two demonstration projects have shown that photovoltaics can appropriately meet small domestic power needs in off-grid applications, providing clean, reliable, maintenance-free electricity which is far more convenient than other electricity producing technologies. Photovoltaics proved to be very much more cost effective than petrol generators, and were also found to be cheaper than coventionally used energy sources such as paraffin, candles and batteries. Both of the demonstration project households were extremely satisfied with the PV systems, which have resulted in significant improvement in quality of lifestyles. However, based on the overall performance of the systems it was recommended that more research was needed, using local conditions, and data to develop better PV system design and sizing methodologies.
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Hung, Guo-Kiang, i 洪國強. "A Grid Connected Residential Photovoltaic Inverter". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/83384397742409524894.
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博士國立臺灣大學
電機工程學研究所
90
Analysis and implementation of a grid connected residential photovoltaic inverter are provided in this work. The PV inverter equipped with solar panels can be viewed as a dispersed generation unit. The rated output power is 4kW, which satisfies general residential electricity consumption. The power circuit of the PV inverter is composed of two stages — the dc/dc boost converter and the full-bridge inverter. This kind of design allows flexible combinations of solar modules. The control circuit is based on a microprocessor. There are mainly three design goals of a grid connected PV inverter: Maximum power point tracking of solar panels, output current control of the inverter, and islanding phenomenon detection. They are implemented respectively by perturb-and-observe method, deadbeat current control, and automatic phase shift method. This work focuses especially on the delay effect caused by digital control. The predictive current observer based control algorithm successfully solves the problem. The automatic phase shift method, on the other hand, reduces the non-detection possibility of conventional islanding detection techniques. Simulation and experimental results are provided for verification.
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Omran, Walid. "Performance Analysis of Grid-Connected Photovoltaic Systems". Thesis, 2010. http://hdl.handle.net/10012/4943.
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Solar energy is one of the most promising renewable resources that can be used to produce electric energy through photovoltaic process. A significant advantage of photovoltaic (PV) systems is the use of the abundant and free energy from the sun. However, these systems still face major obstacles that hinder their widespread use due to their high cost and low efficiency when compared with other renewable technologies. Moreover, the intermittent nature of the output power of PV systems reduces their reliability in providing continuous power to customers. In addition, the fluctuations in the output power due to variations in irradiance might lead to undesirable performance of the electric network. The support of governments, electric utilities, researchers and consumers is the key to overcoming the aforementioned obstacles and enhancing the maturity of the technology in this field.
The primary objective of the research proposed in this thesis is to facilitate increasing the penetration levels of PV systems in the electric network. This can be achieved by quantifying and analyzing the impacts of installing large grid-connected photovoltaic systems on the performance of the electric network accurately. To achieve this objective, the development of a new and intelligent method is introduced. The method utilizes the available data efficiently to produce accurate realistic results about the performance of the electric network without overestimating or underestimating the impacts of the PV system. The method utilizes historical environmental data collected over a number of years to estimate the profile of the output power of the PV system. In addition, the method considers the actual data of the electric network. Hence, the interaction between the output power of the PV system and the electric network components can be simulated to identify the possible operational problems.
After identifying the operational problems that might arise due to installing PV systems, especially due to power fluctuations, different strategies that can mitigate these problems are studied in detail. These strategies include installation of energy storage devices, use of dump loads, and operation below the maximum power point. Upon studying the mitigation strategies, their economical aspects are investigated. The economical aspect is crucial for PV systems because of their high cost, which is reflected on the price of the energy produced by them.
The presented research integrates techniques from different fields of engineering such as data mining, mathematical optimization and power systems. This research is expected to contribute to the advancement of PV technology by introducing methods that will help in carrying out in-depth evaluation of the performance of PV systems and providing feasible solutions to the operational problems that might arise from the installation of these systems.
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Tang, Zong-Bin, i 唐宗賓. "Implementation of a Grid-Connected Photovoltaic System". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/62468966854747751027.
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Liao, Wei-Cheng, i 廖偉呈. "The Study of Grid-Connected Photovoltaic System". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/79486649079283799225.
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碩士逢甲大學
資訊電機工程碩士在職專班
99
In recent years the energy crisis problem is addressed and taken seriously by different countries in the world. Rapid growths of engineering and financial industries, global warming and shortage of traditional energy sources all adds up to make exploitation and development of renewable energy sources an inevitable trend. Among various green electrical energy technologies, photovoltaic is put a great emphasis on because its convenience and usability are much greater than other renewable energy sources. Energy saving and carbon emission reduction is a popular topic throughout the world, and there’s no difference in Taiwan. In the month of May of the 98th year of Republic, Taiwan officially launched the project of “The 98th year investment project in broadening of public constructions for encouraging economic growth–setting up demonstrations of photovoltaic systems in public constructions”. This project is to subsidize municipal organizations in the country setting up the photovoltaic demonstration system. The said organizations can apply for one of the following categories for their constructions: Central demonstration, Educational demonstration and others. In this thesis we shall discuss the Grid-connected Photovoltaic System. There will be an introduction of its overall structure and characteristics, and then 3 main points of the system, which includes Maximum Power Point Tracking, current control of DC/AC inverter and detection of islanding, will be briefly examined. The goal is to find out the photovoltaic system’s overall greatest efficiency, ways to maintain its level and to put a good use to it.
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Lai, Ming-Wei, i 賴明緯. "Design of a 1kW Grid-Connected Photovoltaic Inverter". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/02157378906449440965.
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碩士國立彰化師範大學
電機工程學系
99
This thesis proposed a 1kW grid-connected photovoltaic inverter, which is mainly constructed by a single-phase full-bridge inverter, a low pass filter and a maximum power tracking controller. That makes the solar photovoltaic module operating at maximum power and feed power into the utility power operation. The proposed grid-connected photovoltaic inverter is a single-stage circuit architecture with a single current feedback control, making the circuit design and control easier. The bipolar voltage switching control is used in the single-phase full-bridge inverter. The low-pass filter is an LCL-type. The maximum power tracking control is realized by using a micro-processer HT46R24. Finally, a 1kW grid-connected photovoltaic inverter is designed and implemented to verify the feasibility. The experimental results show that the proposed system can achieve the maximum peak power tracking and output units power factor to fed into the utility power.
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Lee, Ting-peng, i 李天鵬. "Study of Grid-Connected Photovoltaic Power Supply Systems". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/39042409838425038852.
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博士國立臺灣科技大學
電子工程系
98
This dissertation aims to study and develop two novel grid-connected photovoltaic (PV) systems. The first PV system is parallel-connected to an electric power grid with a power factor corrector (PFC) for supplying DC loads. The balanced distribution of the power flow between the utility and the PV panels is achieved automatically by regulating the output DC voltage of the PFC. The proposed topology, which can effectively transfer the tracked maximum power from the PV system to the DC load, while the unity power factor is obtained at the utility side. The DC-connected Photovoltaic system has the advantages of high reliability and low cost due to its simple topology and easy control. The conventional AC-connected photovoltaic system consists of a DC/DC converter for tracking the MPP of the photovoltaic panels and a DC/AC inverter for supply AC voltage output. An interesting alternative solution is the application of a single-stage topology. Thus, this dissertation also presents the second PV system that is a single-stage full-bridge inverter topology with maximum power point tracking (MPPT) function. High MPPT accuracy and high conversion efficiency can be achieved by using a simple single-stage configuration. The advantages of the single-stage topology are a high power density, simple configuration and low circuit cost compared with the conventional two-stage structure. The operation principles and design considerations of the proposed DC and AC grid-connected PV systems are discussed and analyzed in details. The laboratory prototypes are implemented and tested. The experimental results are shown to verify the feasibility of the studied schemes.
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Fry, Bryan. "Simulation of grid-tied building integrated photovoltaic systems". 1999. http://catalog.hathitrust.org/api/volumes/oclc/42195072.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1999.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (p. 332).
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SHIH, TZU-CHIANG, i 施子強. "Study of Grid-connected Photovoltaic System Operation Efficiency". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/u97w7s.
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碩士國立高雄應用科技大學
電機工程系博碩士班
106
Study of Grid-connected Photovoltaic System Operation Efficiency Student：Shih Tzu-Chiang Advisor：Dr.Lee Zong-En Institute of Electrical Engineering National Kaohsiung University of Applied Sciences ABSTRACT Our country’s energy sources have highly relied on fossil fuel importation from foreign countries overseas for several decades. However, due to climate change concerns and public awareness of environmental protection issues, greener renewable energy becomes an alternative source in recent years to reduce our demand on foreign fossil fuel importation. Renewable energy weights even more important as the domestic energy demand continues to grow, and especially as the base power plant capacity constraint caused by “No More Nuke” policy and the nature of an island state’s isolated power grid. The thesis includes the introduction to Photovoltaic (PV) power plant system architecture, the functionalities of grid-connected PV inverter, and the grid-connected PV system operating efficiency analysis. In which there are several sub-topics are studied: Operating efficiency analysis of the grid-connected PV module installation orientation, operating efficiency before and after the PV module surface cleaning, operating efficiency comparisons between single high-power inverter configuration and multiple low-power inverter configuration, operating efficiency analysis in the rooftop PV system module tilting changes, grid-connected PV system malfunctioning cases review, thermal effect on the grid-connected PV system operating efficiency, and many more. The study results can provide best practice guidelines to professionals when conducting PV power plant planning, PV power plant operation and maintenance (O&M), PV power generation efficiency analysis from O&M record data, and prevention of PV system malfunctioning. And the O&M cycle proposed in the thesis can also help to maximize a PV system operating efficiency and its productivity and profitability. Keywords:Renewable Energy、Photovoltaic System 、Operation Efficiency
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Oram, Sunita. "Estimation of Grid Frequency for a Photovoltaic System". Thesis, 2017. http://ethesis.nitrkl.ac.in/8916/1/2017_MT_SOram.pdf.
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The dissertation presents a synchronization technique meant to provide an estimation of grid frequency0and positive sequence component of three phase distorted grid voltages. Although the Phase Locked Loop (PLL) has been broadly used as an execution technique, it requires an effort when the grid voltages are severely distorted by harmonics and unbalances. Thus the performance of the PLL can be further improved by using an observer with the existent PLL. The positive sequence voltage from the distorted grid voltage is estimated with the help of observer and PLL. Thus in this thesis an observer based PLL method is used for frequency estimation. Since the observer based PLL technique is immune to noise and distortions which are present in power system signals, it is used for distributed generation units, ex: solar power generation systems that use power electronics converters as their integral part. Under the polluted grid conditions, the performance of observer based PLL method have been performed by in MATLAB/SIMULINK. And also a hardware prototype MATLAB interfaced XILINX SYSTEM GENERATOR have been performed to prove the effectiveness of the proposed technique. The results so obtained from Software (MATLAB) Simulation and hardware (XILINX) simulation have been compared and the performance of the proposed method have been discussed.
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Toppo, Neha Mary. "Control of Three Phase Grid Connected Photovoltaic System". Thesis, 2018. http://ethesis.nitrkl.ac.in/9650/1/2018_MT_216EE3291_NMToppo_Control.pdf.
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To counter environmental pollution arising out of fossil fuel power generation,the world is gradually shifting towards renewable sources of energy, with solar energy leading at the front. In a grid-connected solar PV system, the energy generation system and utility grid are interfaced by using power electronics converters which are commonly based on a VSI (voltage source inverter) connected to the mains supply network, which is used to regulate power flow and ensuring operation with unity power factor. The grid requirements are improved power quality, Good transient response during fault conditions, grid synchronization and independent control of active & reactive power and etc.
To achieve this requirement of the grid, here we designed a 10kW PV system which is to be interfaced to a utility grid to be performed. This project represents athree-phase, single-stage grid integrated solar PV system. The proposed system serves for power factor correction,the maximum power point tracking (MPPT), the grid 5 currents balancing and harmonics mitigation of loads connected at the PCC (point5 of common coupling). The solar photovoltaic system uses a three- phase VSC (voltage source converter) to perform these functions. This system extracts the solar energy from the photovoltaic system and feeds to the grid.MPPT algorithm is put to use for extracting maximum power from Photovoltaic system. There are many types of MPPT algorithms are there, but especially which are widely used is perturb and observer and incremental conductance algorithm. Here, the proposed system used the incremental conductance which is more accurate and more efficient. The reference DC link voltage of voltage source converter is also decided by the MPPT algorithm.
In a simplified way, the control algorithm of a solar photovoltaic system consists of two parts, in the first part the MPPT decides the reference D.C. link voltage and secondly the VSC is controlled by the use of control functions. The PV system voltage is maintained at the reference which is controlled by a PI(proportional integral)controller using an MPPT algorithm. For controlling the VSC, an Improved linear sinusoidal tracer (ILST) and Damped-second order generalized integrator (Damped-SOGI) is proposed. The main characters of the Improved linear sinusoidal tracer control algorithm are fast convergence, control simplicity while the Damped-SOGI is having the higher converging state, good noise immunity response and improved steady-state performance. The fundamental component of the load current is extracted by using an ILST and a Damped-SOGI based control algorithm, zero crossing detectors and sample and hold log are used to extract the active power component of load currents. PI controller is used to estimate the loss component of VSC and reference grid currents are estimated by combining all these components. The sensed grid currents and the reference grid currents are compared and a current controller is used for producing the switching pulses for the grid VSC interfaced. The unity power factor (UPF),as well as the sinusoidal balancing of grid currents, are controlled by the VSC. The currents injected into the grid are synchronized using unit templates derived from PCC voltages. Only active power is exchanged through the grid because the grid currents are at UPF. The total active power in the system must be balanced among the grid, the loads and the SPV. There is a comparison between the Damped SOGI and ILST algorithm on the basis of THD and other waveforms. The simulation results are obtained by using MATLAB/Simulink for controlling the active current between the PV-grid systems.
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Singh, Amresh Kumar. "Investigations on control algorithms for solar photovoltaic grid interfaced systems". Thesis, 2018. http://eprint.iitd.ac.in:80//handle/2074/8009.
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Pahari, Om Prakash. "Robust and Adaptive Grid Synchronization Control of a Two Stage Grid-Connected Photovoltaic System". Thesis, 2020. http://ethesis.nitrkl.ac.in/10154/2/2020_PhD_OPPahari_513EE1004_Robust.pdf.
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In view of supplementing power generation to meet increasing load demand while minimizing environmental pollution, more attention is currently given to use renewable power extraction for Photovoltaic (PV) and Wind energy conversion system. Amongst all the renewable power generation options, PV power generation is being considered as the most suitable one owing to the abundant availability of solar irradiance with pollution¬free operation. A PV system can be operated as standalone or grid connected modes. The thesis focuses on design, development, and practical realization of robust and adaptive control schemes for effective synchronization of a two¬stage three¬phase Grid Connected Photovoltaic System (GCPVS) to the utility grid. The PV power varies continuously during the day, and PV current and voltage characteristics depend upon the irradiation and ambient temperature, respectively. Therefore, to track this random variation in the Maximum Power Point Tracker (MPPT), adaptive MPPT algorithms is necessary on the PV side. On the grid side, the grid voltage distortions, corrupts the grid synchronization controllers. To resolve these issues, a robust controller needs to be designed. The thesis first designs a Adaptive MPPT controller to improve the Maximum Power Point (MPP) tracking performance. The classical MPPT controllers such as P&O has fixed step size, and its MPP tracking performance is influenced by predefined parameters such as perturbation size, sampling time and initial duty ratio. Therefore, fast tracking of the MPP through these MPPT algorithms is difficult. To resolve these issues, a PI controller is employed to generate a variable step size duty ratio, to improve the tracking performance of this proposed Improved Adaptive Perturbed and Observed (IAPO) MPPT algorithm. In this algorithm, the step size is varied based on the PV power variation, which is embedded as an adaptive feature to a PI controller. This adaptive feature results in fast tracking of the MPP even during transients, less oscillations of DC link voltage during steady state, and least dependence on predefined parameters such as initial duty ratio. Subsequently, to achieve current control for synchronization, an Integral Sliding Mode Controller (ISMC) is designed in which issues regarding the harmonics in the grid injected current is reduced. The classical PI current controller performance deteriorates due to grid voltage distortions and hence there is a need to employ harmonic suppression schemes. But, this slows down the current controller dynamics. Whereas, the ISMC aids in achieving faster dynamics in face of modeling and parametric uncertainties. It also suppresses the harmonics in the injected grid current despite the presence of high Total Harmonic Distrotion (THD) vii content in the grid voltage. It is also found to have excellent decoupling of the cross coupling terms and provide independent control of active and reactive current. The ISMC based current controller is then integrated with the IAPO MPPT algorithm for a two stage GCPVS. Its performance is then compared with other control schemes, namely, SMC¬IAPO and PI¬IAPO control schemes. The comparison envisages that with ISMC¬IAPO control approach, the performance of the overall system improves, and this control strategy does provide faster dynamics despite rapid variations in the PV power, uncertainties owing to modeling and parametric variations in the PV system and grid disturbances. It is also found that this ISMC¬IAPO approach gives the best quality current in comparison to ISMC¬P&O, SMC¬IAPO, and PI¬IAPO. The robust performance of the ISMC is then evaluated in grid fault situations where a Vector Current Control with Feedforward (VCCF) control strategy is employed in the control of two stage GCPVS to deliver balanced three phase currents to the gird. The control of two stage GCPVS in the Low Voltage Ride Through (LVRT) situation becomes a real challenge. It is because the control operation needs to regulate the DC link voltage at its nominal value. Therefore, to transfer the reactive power, the PV panel is operated in the de¬rated mode of operation. This is only possible if MPPT operation is halted and boost converter is operated in constant duty ratio mode. This new duty ratio and reactive current reference are calculated based on the percentage of voltage dips. The ISMC based VCCF strategy is evaluated in the three phase symmetrical and two phase unsymmetrical fault. The ISMC provides both active and reactive current to the grid. The ISMC is compared with a PI controller based VCCF strategy and found to have good performance in damping the inrush currents that arise in the event of fault occurrence and fault clearance. All these control algorithms are simulated in MATLAB/Simulink environment followed real-time implementations on a prototype PV system. A prototype of 2 kW PV system is developed in the laboratory. The aforesaid grid synchronization algorithms were then implemented and verified in real-time on the prototype GCPVS, and results obtained are analyzed.
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SUKESH, NIKHIL. "Single Stage Grid-Connected Micro-Inverter for Photovoltaic Systems". Thesis, 2012. http://hdl.handle.net/1974/7317.
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This thesis presents a novel Zero Voltage Switching (ZVS) approach in a grid connected single-stage flyback inverter without using any additional auxiliary circuits. The soft-switching of the primary switch is achieved by allowing negative current from the grid-side through bidirectional switches placed on the secondary side of the transformer. Basically, the negative current discharges the MOSFET’s output capacitor thereby allowing turn-on of the primary switch under zero voltage. In order to optimize the amount of reactive current required to achieve ZVS a variable frequency control scheme is implemented over the line cycle. In addition, the bi-directional switches on the secondary side of the transformer have ZVS during the turn-on times. Therefore, the switching losses of the bi-directional switches are negligible. A 250W prototype has been implemented in order to validate the proposed scheme. Experimental results confirm the feasibility and superior performance of the converter compared to the conventional flyback inverter.Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2012-07-06 16:24:13.385
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Jiang, Ding-long, i 江定龍. "Performance evaluation and verification of grid-connected photovoltaic systems". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/89313342467273185822.
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碩士健行科技大學
電機工程系碩士班
102
This thesis aims to explore the differences generation power of fixed type and single-axis tracking type photovoltaic (PV) system, different serial numbers of the PV system starting characteristics under the same maximum power point tracking control and south and central of Taiwan the optimal tilt angle design for PV system installation. In this thesis, respectively College of Electrical Engineering & Computer Science of Chien Hsin University top floor refrigerant driven tracking type 1.14kWp,fixed type 1.14kWp, HIT 1.0kWp, HIT 1.2kWp, Kenting, Pingtung County 21.94kWp, Linluo, Pingtung County 10.08kWp, and Ershui, Changhua County 18.24 kWp all seven sets PV systems was the subject for the study. First, the Solar Pro software package was used for PV system simulation, and then compared with monitoring data. The verify and analysis results showed that the tracking type PV system generating power than Fixed PV system 1.145 times more electricity. The different serial numbers of the PV system under the same maximum power point tracking control, the DC input power will affect the start time to the maximum power point tracking. At Taiwan''s Changhua PV system, the tilt angle optimized is 19.3 degrees, while Taiwan''s Pingtung PV systems, its tilt angle optimized is 18.9 degrees. In this thesis, the Solar Pro software package was used to analyze the generating capacity, IV curves, shading impact and performance of power generation systems of the seven sets PV systems. The simulation results then compared with monitoring data for correcting simulation program parameters, future PV system planning and performance evaluation of photovoltaic generation system.
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Chang, Jheng Fu, i 張政富. "Design and implementation of a grid connected photovoltaic system". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/58306657649855555210.
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碩士清雲科技大學
電機工程研究所
95
A grid connected PV system, which consists of PV modules, a maximum power point tracking (MPPT) controlled boost converter to let the PV module operate at MPPs with respect to different insolation changes and a current controlled full bridge inverter with LCL filter to inject sinusoidal current into utility, is proposed in this thesis. The MPPT control method is derived from incremental conductance (InCond) method and the tracking and regulation behaviors to keep the PV module operated at MPP. As a result, the designed MPPT can track insolation change quickly than the integrated InCond and perturbation & observation (P&O) method via the same hardware implementation. Then, the generated DC energy of the PV modules is converted to injected sinusoidal current into utility through the grid connected inverter. This inverter has an inner current control loop to let inductor current track its referent sinusoidal current closely and an outer voltage controller to generate the injected current command with respect to insolation intensity. Furthermore, an insolation simulator was built to generate various insolation patterns through microprocessor. With the help of the insolation simulator, the limitation of the nature environment is removed and can do all the experiments in side the libratory. Finally, some simulations and experimental results are provided to demonstrate the effectiveness of the designed grid connected PV system.
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Lu, Shao-hsin, i 呂紹新. "Control of Buck Converter in Grid Connected Photovoltaic System". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/79824896163464954204.
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碩士國立中央大學
電機工程研究所
99
This study presents a grid-connected photovoltaic system which is comprised of two stages: Buck DC/DC Converter and Current Source Inverter (CSI). The converter is used to buck the voltage and boost the current and provides a stable input power to the next stage. Conventionally, the electrolytic capacitor is used to isolate the disturbance caused by the ac output signals. The proposed control mechanism to the converter achieves an effective isolation from the grid-connected system, and also significantly reduces the size of electrolytic capacitor, so that the photovoltaic system provides a stable output. On the other hand, the CSI implements the inverter stage with a simpler control mechanism and has the inherent short circuit protection and the rapidness in system control. This study also proposes a simple way to obtain a reference voltage which makes sure the photovoltaic array to operate at the maximum power point.
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Chang, Sheng-Kai, i 張勝凱. "Novel Seven-Level Grid-Connect Photovoltaic Power Generation System". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/b9u3f7.
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碩士國立高雄應用科技大學
電機工程系博碩士班
101
A photovoltaic power generation system consists of a dual output DC-DC power converter and a multi-level DC-AC power converter is developed in this thesis. A dual output DC-DC power converter with the functions of output voltage into a multiple relationship and maximum power point tracking is required. The multi-level DC-AC power converter includes a dual buck power converter and a full-bridge power converter. The dual buck power converter generate a four-level DC voltage. The full-bridge power converter is switched in low frequency and synchronously with the utility voltage and it convert this four-level DC voltage to a seven-level AC voltage inject into grid; it can also operate to an active power filter to compensate harmonic current.Computer simulation and 1.2kW hardware prototype are developed to verify the performance of the propose novel seven-level grid-connect photovoltaic power generation system. Both simulation and experimental results show that the performance of the propose novel seven-level grid-connect photovoltaic power generation system has the expected results.
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Das, Anasuya. "The H∞ Control Method of Grid-Tied Photovoltaic Generation". Thesis, 2016. http://ethesis.nitrkl.ac.in/9127/1/2016_MT_ADas.pdf.
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Renewable energy is the alternative sources of electrical energy to fulfill energy shortage. micro grid allows to connect multiple renewable energy sources to it. Photovoltaic (PV) generation is one of the major renewable energy sources. PV generation systems directly connected to micro grid brings some problems like voltage deviation, current fluctuation etc. which brings instability into the system. Thus, a smooth micro grid connection with PV system is required. Here H∞ control method based on model matching technique has been adopted for our system. To extract maximum power from PV array, P and O MPPT algorithm has been adopted.
Mathematical modellings for the design of H∞ Controller has been done here.Using Robust control tool box gain of the controller are found, all the eigen values of H∞ control system have negative real part, Hence voltage tracking control system is stable.
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Mohanta, Prasanta Kumar. "Modeling and Control of a Grid Connected Photovoltaic System". Thesis, 2016. http://ethesis.nitrkl.ac.in/9251/1/2016_MT_PKMohanta.pdf.
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At present scenario, renewable energy sources have emerged as best alternative0source of energy for0future and to alleviate the environment pollution0problems. Renewable energy sources like solar energy, wind energy system etc. when connected to grid, termed as micro grid, uses0power electronics converters so as to interface between renewable energy system0and utility grid. Although solar energy conversion efficiency is very low, it has been preferred widely due to its abundant nature. An attempt has been taken to develop an improved MPPT which uses d-axis grid current and dc link voltage as reference. It not only tracks the maximum power effectively but also provides a dynamic response to the fast changing atmospheric condition. The converters used for interfacing, are basically a voltage source0inverter (VSI) connected to the source0network, operated in order to achieve0objectives such as to control the power0flow and also to have operate at unity0power factor. The grid is required to have independent0control of active & reactive power, proper grid0synchronization, improved power0quality and good transient response0during any fault conditions etc. The voltage0oriented control (VOC) implemented on the grid0side converter is universally adapted for independent control of the active and reactive power0of a grid as it is controlled in0synchronous rotating frame. However, the dynamic response0of grid, during abnormal condition, is very0sluggish and poor0power quality. In order to design a0controller for robust performance and0to know its control characteristics, 0VSI needs to be modeled accurately. This project0has taken an attempt to derive the small0signal analysis of a three phase0grid connected VSI and further, relevant0transfer functions have been0obtained from the model in order0to analyze the system performance, to0be used for designing a0controller by utilizing bode plots. The studied system is0then modeled and simulated in the0MATLAB-Simulink environment.
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Sebastian, Sharon. "Grid Connected Photovoltaic Power System with Active Power Filtering". Thesis, 2016. http://ethesis.nitrkl.ac.in/9347/1/2016_MT_SSebastian.pdf.
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The solar energy become a popular and environmental friendly solution for meeting demand of the increasing demand for electric power. The photovoltaic system has now become grid connected system from stand-alone system as it was previously. Now feed in tariff (FIT) has made it a distributed energy (DG) sources in many countries around the world.
The power quality of the grid is being degenerated by the injection of the current by the grid connected PV system with the converters used for DC to AC conversion or the inverter functioning unaware of the harmonics injected by it. Additionally the voltage harmonics is also introduced by the current injected with filtering. Especially the increasing penetration of the DGs in low voltage networks which uses the PV energy as source has had worsened the situation. The rising use of non-linear load has resulted in excessive harmonic pollution resulting in losing of reliability and power quality of the system. Active power filtering can be performed by following various theories one such popular theory is the one using instantaneous power theory proposed and cross vector theory. Other theories like power balance theory and Synchronous reference frame is also effective in APF for distorted and unbalanced supply along with power injection from PV source.
Combining the PV system and APF through a single three phase voltage sourced inverter (VSI) thus making the full utilization of the switching devices at all times is the objective achieved. The PV power is used for the DC voltage regulation and the surplus power from the PV source is also fed through the voltage source inverter (VSI) to the load or the grid. For improving the efficiency single stage conversion is used. Current control is used with reference current generated for both the filtering of harmonics and the MPPT of PV panel and the DC voltage regulation. P&O algorithm with variable perturbation size was used for the efficient tracking of the MPP.
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Khalifa, Ahmed Said. "Control and Interfacing of Three Phase Grid Connected Photovoltaic Systems". Thesis, 2010. http://hdl.handle.net/10012/5706.
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Solar power is considered a very promising source for electric power generation. The abundance of sunlight over a large area of the earth surface gives rise to several applications of photovoltaic systems. Electricity can be generated from sunlight either directly by employing the photovoltaic effect, or by using energy from the sun to heat up a working fluid that can be used to power up electricity generators. These two technologies are widely used today to provide power to either stand-alone loads or for connection to the power system grid.
Maximum power point tracking (MPPT) is a very important consideration that is taken into account when building a new photovoltaic power system. This is needed in order to extract maximum power output from a PV array under varying atmospheric conditions to maximize the return on initial investments.
Several techniques have been used to tackle this problem including perturb and observe (P&O), incremental conductance (IncCond) and fuzzy logic based algorithms. Judging between these techniques is based on their speed of locating the maximum power point (MPP) of a PV array under given atmospheric conditions, besides the cost and complexity of implementing them. The P&O and IncCond algorithms have a low implementation complexity but their tracking speed is slow. Fuzzy logic techniques are faster but suffer from high implementation complexity.
One of the goals of this thesis is to present an MPPT algorithm implementation that is based on the fractional open circuit voltage method. This technique is easy to implement and offers a fast tracking speed for the MPP of a PV array. It provides an approximation within 4-5% of the maximum power point, which is a tradeoff between the speed and accuracy of operation around the MPP. It offers a speed advantage in grid connected PV systems. The P&O algorithm, which is very common, is difficult to implement under these conditions due to its poor response time.
There is also a need for developing control techniques for three phase grid connected PV systems including a method for DC link voltage control that can stabilize the voltage at the inverter input. This area of research is currently growing with the increase in number of PV installations backed up by government incentives in several countries. In addition to the previously mentioned points, this work is intended to be used in further research to replace the representation of PV arrays as a simple DC source when included in power system studies. That is a basic assumption and does not take into consideration the various dynamics caused by changing solar irradiation and surface temperature of the array.
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Chung, Yi-Chih, i 鐘乙智. "Design and Implementation of Grid-Connection Single-Stage Photovoltaic Inverter". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/82577896404555606146.
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碩士國立高雄第一科技大學
電子工程研究所
99
In this thesis, a grid-connection single-stage PV inverter system is presented, which can deal with solar energy and performs power conditioning. To draw maximum power from PV arrays, double-linear approximation (DLA) algorithm is incorporated to achieve maximum-power-point tracking (MPPT) for PV arrays. The DLA is based on that the trajectories of maximum power point varying with irradiation and with temperature are approximately linear, respectively. With the DLA, the inverter system can determine maximum power point instantaneously and then, calculates current command easily. Thus, complicated calculation and perturbation about an optimal point can be avoided. In this thesis a corresponding circuit to realize DLA is carried out as well, of which configuration is simple. As a result, the proposed circuit is cost-effective and can be embedded into inverter system easily. From simulated and experimental results, the proposed DLA algorithm has been verified and the feasibility of the PV inverter system is also demonstrated.
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Liu, Tsung-Hsien, i 劉宗憲. "Common-Mode Current Reduction for Transformerless Grid-Connected Photovoltaic Inverters". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/88554855466969352699.
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碩士國立臺灣科技大學
電機工程系
97
This thesis proposes a novel inductance-capacitance filter to improve the common-mode current for transformerless grid-connected photovoltaic (PV) inverters. Reduction of the voltage of PV negative electrode with respect to ground is then resulted to avoid shortening the service life of PV array and harming the personnel safety. A boost-type dc-dc converter is introduced to boost the PV array voltage from 560V to 670V on output side of PV array for inverter input. The three-phase full-bridge inverter designed uses voltage space vector pulse-width modulation to convert dc-link voltage to three-phase alternating current for grid-connection. In this thesis, a 32-bit digital signal processor is adopted as the control core for reducing the circuit complexity. The Powersim simulation software is used to analyse the suppression effect of the proposed inductance-capacitance filter. A 10 kW prototype of transformerless grid-connected three-phase PV inverter is built. Experimental results show that the voltage of PV negative electrode to ground is reduced from 1,793V to 181V, and the corresponding common-mode current is reduced from 253 mA to 99 mA, respectively. The proposed inductance-capacitance filter is better than current passive techniques in the suppression effect of common-mode current. Thus it is applicable for transformerless grid-connected photovoltaic inverters.
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Li, Ming Chieh, i 李明杰. "Design and Implementation of Small Capacity Grid-Connected Photovoltaic Inverter". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/21673018490794207824.
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碩士國立聯合大學
電機工程學系碩士班
95
The development of regenerative power is more and more emergency due to the severer international environmental protection regulation and the predictable shortage of the conventional energy sources. The solar power is clean and inexhaustible and thus has seen as the most important renewable energy of this century. How to feed power to the grid with photovoltaic (PV) modules in a high efficiency way is an attractive research topic recently. Unlike the conventional large capacity power generation with PV array, this thesis develops a small system that can feed unity power factor power to the grid with only one PV module through an inverter formed by a DC/DC converter with current source output and a full-bridge converter with line-frequecy switching. Two topologies of the inverter based on the flyback converter are presented in this thesis. The inverter recycles the leakage inductance power with the clamped capacitor and cascades the secondary winding with the converter output to achieve the high step-up voltage. With discontinuous conduction mode (DCM) of the high step-up flyback converter and synchronous and semi-sinusoidal modulation of the main switch, the peak current of the switch and the output peak current of the converter will be semi-sinusoidal. Through the inversion of the full-bridge inverter and the low-pass filtering of the LC filter, the final current fed the grid will be sinusoidal and in phase with the voltage. Although the proposed circuits are two stage, they have high efficiency due to the efficiency of the high step-up flyback is very high and the full-bridge converter has very low switching loss. For the convenience of experiment this thesis also develops a PV module emulator realized with a half-bridge converter to replace the real PV module. Two 80W systems are built based on the proposed design. The effectiveness of the proposed methods are confirmed with some PSIM simulation and experimental results.