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1
Zhang, Qiufang, Zheng Shi, Ying Wang, Jinghan He, Yin Xu, and Meng Li. "Security Assessment and Coordinated Emergency Control Strategy for Power Systems with Multi-Infeed HVDCs." Energies 13, no. 12 (June 19, 2020): 3174. http://dx.doi.org/10.3390/en13123174.
Анотація:
Short-circuit faults in a receiving-end power system can lead to blocking events of the feed-in high-voltage direct-current (HVDC) systems, which may further result in system instability. However, security assessment methods based on the transient stability (TS) simulation can hardly catch the fault propagation phenomena between AC and DC subsystems. Moreover, effective emergency control strategies are needed to prevent such undesired cascading events. This paper focuses on power systems with multi-infeed HVDCs. An on-line security assessment method based on the electromagnetic transient (EMT)-TS hybrid simulation is proposed. DC and AC subsystems are modeled in EMTDC/PSCAD and PSS/E, respectively. In this way, interactions between AC and DC subsystems can be well reflected. Meanwhile, high computational efficiency is maintained for the on-line application. In addition, an emergency control strategy is developed, which coordinates multiple control resources, including HVDCs, pumped storages, and interruptible loads, to maintain the security and stability of the receiving-end system. The effectiveness of the proposed methods is verified by numerical simulations on two actual power systems in China. The simulation results indicate that the EMT-TS hybrid simulation can accurately reflect the fault propagation phenomena between AC and DC subsystems, and the coordinated emergency control strategy can work effectively to maintain the security and stability of systems.
2
An, Wenjing, Yuanchao Yang, and Geyi Wu. "Research on optimal power flow of AC/DC hybrid system for civil more electric aircraft." Journal of Physics: Conference Series 2741, no. 1 (April 1, 2024): 012017. http://dx.doi.org/10.1088/1742-6596/2741/1/012017.
Анотація:
Abstract Modern civil more electric aircraft often use AC/DC systems instead of AC systems to reduce the weight of the power system. Compared with the AC/DC system of the land power grid, the aircraft power system needs to pursue economic operation mode under more complex security constraints. This paper establishes the optimal power flow model of the AC/DC hybrid system of more electric aircraft, which takes minimizing the active power loss of the line as the optimization objective, including the steady-state operation constraints and security constraints of the AC/DC system. The interior point method and prediction correction interior point method are used to solve the model. Then, based on the simplified steady-state model of the B787 power system, the model and algorithm are verified by experiments. The experimental results show that by optimizing the power flow distribution of the power system, the power utilization efficiency of the system has been significantly improved, and its stability and reliability can also be better guaranteed.
3
Wang, Bao Hua, and Zhong Ke Shi. "Dynamic Adaptive Sliding Mode DC Power Modulation Controller in Parallel AC/DC Transmission System." Advanced Materials Research 433-440 (January 2012): 6783–88. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.6783.
Анотація:
The effective DC power modulation controller influences the security and stability of AC/DC interconnected power system significantly. Based on the direct feedback linearization model of parallel AC/DC transmission system, the DC power modulation controller is designed by using the dynamical adaptive sliding mode control designing method. Using an adaptive technique to estimate the switching control gain and damping coefficient, the dynamical sliding surface is proposed to eliminate tremble. The proposed adaptive sliding mode control scheme can be implemented without the requirement that the bounds of the uncertainties and the disturbances should be known in advance; meanwhile its design is very simple. The simulation results show that this proposed controller is superior to the nonlinear H∞ DC power modulation controller in damping oscillation and robustness.
4
Piao, Longjian, Laurens de Vries, Mathijs de Weerdt, and Neil Yorke-Smith. "Electricity Markets for DC Distribution Systems: Design Options." Energies 12, no. 14 (July 10, 2019): 2640. http://dx.doi.org/10.3390/en12142640.
Анотація:
DC distribution systems (DCDSs) are a promising alternative to AC systems because they remove AC-DC conversions between renewable sources and loads. Their unique features compared to AC include low system inertia, strict power limits and power–voltage coupling. In a liberalised electricity market, merely applying an AC market design to a DCDS cannot guarantee the latter’s supply security and voltage stability; new markets must be designed to meet DC challenges. This article identifies the key design options of DCDS electricity markets. To identify these options, we develop a comprehensive design framework for local electricity markets; to our knowledge, we provide the first such analysis. Whereas previous studies focus on separate aspects of DCDS markets, we widen the scope to include the role of market architecture and investigate the arrangements of sub-markets. As an illustration, we demonstrate three promising DCDS market designs that can be defined in our framework, and provide a first assessment of their performance.
5
Zhang, Ningyu, Shengjun Wu, Haiyun An, and Xinyao Zhu. "Security-Constraint Unit Commitment for AC/DC Transmission Systems with Voltage Stability Constraint." Journal of Electrical Engineering & Technology 15, no. 6 (September 7, 2020): 2459–69. http://dx.doi.org/10.1007/s42835-020-00521-7.
6
Zhang, Ningyu, Qian Zhou, and Haoming Hu. "Minimum Frequency and Voltage Stability Constrained Unit Commitment for AC/DC Transmission Systems." Applied Sciences 9, no. 16 (August 19, 2019): 3412. http://dx.doi.org/10.3390/app9163412.
Анотація:
An increased use of the high-voltage direct current (HVDC) technologies can have important effects on frequency performance and voltage stability of the receiving-end grid during normal operation as well as during blocking failure. The main reasons are the inherent characteristics of the HVDC such as its much larger capacity than thermal plants and lack of voltage supporting ability to the alternating current (AC) grid. These has led to new challenges for AC/direct current (DC) power grid operators in terms of ensuring power system security. To address these challenges, a unit commitment (UC) of the receiving-end in the AC/DC hybrid grid is presented in this paper. In the proposed model, primary frequency modulation constraints are added to provide sufficient capacity for HVDC blocking. Besides, grid security constraint after secondary frequency regulation is also considered because HVDC blocking failure would cause large range power transfer and transmission lines overload. Meanwhile, voltage stability constraints are employed to guarantee enough voltage supporting capacity from thermal plants at the HVDC feed-in area. Based on the characteristics of the model, Benders decomposition and mixed integer programming algorithm are used to get the optimal transmission power of the HVDC and schedule of thermal units. The study is done by considering the IEEE-39 and Jiangsu power grid in eastern China, containing two HVDC transmission projections respectively. The results are also validated by simulation of different HVDC blocking failure scenarios.
7
Weijie, Zheng, Xu Dechao, Chen Yong, Zhang Xing, and Mu Qing. "Multi Step Transient Hybrid Simulation Framework Design and Practical Engineering Application for AC / DC Power Grid." E3S Web of Conferences 256 (2021): 01010. http://dx.doi.org/10.1051/e3sconf/202125601010.
Анотація:
Based on the large power grid simulation and the existing security prevention and control mode, this paper further integrates the multi-step transient hybrid simulation architecture computing technology to research the high-performance analysis and situational awareness simulation technology of interconnected AC / DC large power grid security and stability characteristics. So as to realize the “panoramic situational awareness, wide area coordinated control, flexible and efficient service” of large power grid, and improve the super large scale power grid Comprehensive security defense and intelligent monitoring level of panoramic, multi-dimensional and three-dimensional.
8
Dhumal, S. D., and Dr P. V. Paratwar. "Estimating the Stability of an AC-DC Hybrid Micro Grid with Multilayer Power Flow While Using Interconnected Converter." International Journal for Research in Applied Science and Engineering Technology 11, no. 6 (June 30, 2023): 1615–22. http://dx.doi.org/10.22214/ijraset.2023.52662.
Анотація:
Abstract: Regionalized networks, also known as micro grids, must be able to operate independently by cutting off their connection to the main grid in order for a system to stay stable. Customers' reliability can be raised by providing a more robust power supply. Due to reversed energy flow from distributed generator units, regional fluctuations, temporary micro grid modes, significant frequency discrepancies in electrically isolated mode operation, as well as financial and supply demand uncertainties, consistency, dependability, and security are in fact the main problems with micro grids. The system is more unstable when electrical energy is transmitted from the AC side to the DC side and from the DC side to the AC side, despite the fact that strengthening the stability of the hybrid micro grid is their main objective. Therefore, a variety of circuit breakers, buck boost converters, grid bidirectional converters, and intermediate IC (Interlinking converter) are utilized to preserve the stability of the hybrid micro grid. This article explains how to build a bidirectional power flow through an interactive converter using stability evaluation using MATLAB. Simulation may improve the circuit's performance for the best outcomes achievable. The most stable hybrid micro grid findings were shown. An interlinking converter is utilized in this work to improve micro grid stability while power is flowing via the AC and DC grids in both directions. The findings might be acquired using a MATLAB simulation. This method also has the advantage of reducing the amount of time needed for the system to stabilize. Consequently, the system will be more dependable and will provide excellent supplies.
9
Yan, Wei, Chong Ding, Zhouyang Ren, and Wei-Jen Lee. "A Continuation Power Flow Model of Multi-Area AC/DC Interconnected Bulk Systems Incorporating Voltage Source Converter-Based Multi-Terminal DC Networks and Its Decoupling Algorithm." Energies 12, no. 4 (February 22, 2019): 733. http://dx.doi.org/10.3390/en12040733.
Анотація:
Existing continuation power flow (CPF) models mainly focus on the regional independent systems, which are not suitable for multi-area AC/DC interconnected systems because the market trading behaviors and security control for power allocation of tie-lines are ignored. This study presents a novel CPF model and its decoupling algorithm for multi-area AC/DC interconnected systems incorporating a voltage source converter (VSC)-based multi-terminal direct current (MTDC) network. This CPF model includes the following unique features: (1) In view of the bilateral power trading contracts among regional subsystems, the nonlinear constraint equations of directional trading active power via interface are derived, and the multi-balancing machine strategy is introduced to realize the active power balance of each subsystem. (2) An accurate simulation method for the security control behaviors of the power allocation in tie-lines is proposed, which includes a specific selection strategy for automatic generation control units and a generation re-dispatch strategy. These two strategies work together to prevent the serious overload in tie-lines during load growth and improve the voltage stability margin of the interconnected bulk systems. (3) The switching characteristic of reactive power control behaviors of VSC stations is simulated in the CPF calculation. In the end, a novel decoupling CPF algorithm based on bi-directional iteration is presented to realize the decomposition and coordination calculation. This decoupling algorithm preserves the precision and convergence of integrated CPF algorithms, and it has an apparent advantage on the calculation speed. Furthermore, this decoupling algorithm also can easily reflects the effects of the control mode changes of VSC stations to the voltage stability margin of AC system. Case studies and comparative analysis on the IEEE two-area RTS-96 system indicate the effectiveness and validity of the proposed CPF model and corresponding decoupling algorithm.
10
Wang, Yanwen, Lingjie Wu, and Shaoyang Chen. "Study on the Mode and Characteristics of SSOs in Hybrid AC–DC Transmission Systems via Multitype Power Supply." Sustainability 15, no. 8 (April 17, 2023): 6763. http://dx.doi.org/10.3390/su15086763.
Анотація:
The impact of subsynchronous oscillation (SSO) on grid security is becoming increasingly prominent with the rapid development of a large new energy base. However, the SSO modes and characteristics in complex power systems where series-complementary AC systems, DC systems, wind farms, and thermal power plants co-exist simultaneously are still not well understood, and relevant research has yet to be conducted. To address these issues, this study aims to investigate the SSO oscillation modes and the participation of specific influencing factors using eigenvalue and participation factor analysis. Additionally, the influence of system operation mode and control parameters on the SSO characteristics is studied through eigenvalue analysis. The findings of this study suggest that multiple oscillation sources and the co-existence of various oscillation patterns in hybrid AC–DC transmission systems cause SSO problems. The SSOs arise due to inappropriate system operation or parameter selection. As the series compensation increases, the system tends to become unstable. The system stability improves when the wind power output increases or the thermal power output decreases while keeping the output power of other sources constant. On the other hand, the system stability decreases as the DC transmission power gradually decreases. In terms of the control parameters, a higher value of the inner-loop proportionality coefficient of the converter current on the rotor side of the wind turbine results in a more unstable system. However, the rotor-side converter outer loop parameters and the stator-side control loop PI parameters have a negligible effect on the oscillation frequency and damping of the system. Matlab time domain simulations are conducted to verify the accuracy of the theoretical analysis.
11
Luo, Xu, Fan Li, Li Fan, Tao Niu, Bo Li, Linxuan Tian, and Hongjie Yu. "Influence of Synchronous Condensers on Operation Characteristics of Double-Infeed LCC-HVDCs." Processes 9, no. 10 (September 23, 2021): 1704. http://dx.doi.org/10.3390/pr9101704.
Анотація:
Considering the advantages that dynamic reactive power (var) equipment (such as synchronous condensers (SCs), which can control var independently and improve voltage stability), SCs are widely used in AC/DC hybrid power grid to provide emergency var and voltage support. In order to evaluate the dynamic var reserve capacity of SCs and analyze the influence of SCs on the operation characteristics of power system, a model with double-infeed line-commutated converter-based high-voltage direct currents (LCC-HVDCs) and SCs is established. Through theoretical derivation and PSCAD/EMTDC simulation, the effects of SCs on the operation characteristics of double-infeed LCC-HVDCs networks are studied. Then, the non-smooth voltage waveform of electromagnetic transient simulation is approximately transformed into smooth waveform by data fitting method. Finally, the processed voltage waveform is searched step by step to explore the boundary of voltage safety region to determine the dynamic var reserve capacity of SCs. The numerical results show that SCs can enlarge the voltage security region of the direct current (DC) subsystem, thus effectively improving the steady-state and transient security level of the double-infeed LCC-HVDCs networks.
12
Saraswathi, Ananthavel, and S. Sutha. "Investigation of Modified Generalized Interline Power Flow Controller (GIPFC) and Performance Analysis." Applied Mechanics and Materials 622 (August 2014): 111–20. http://dx.doi.org/10.4028/www.scientific.net/amm.622.111.
Анотація:
Nowadays in the restructured scenario, the main challenging objective of the modern power system is to avoid blackouts and provide uninterrupted quality power supply with dynamic response during emergency to improve power system security and stability. In this sense the convertible static compensator (CSC) that is the Generalized Inter line power flow controller (GIPFC), can control and optimize power flow in multi-line transmission system instead of controlling single line like its forerunner FACTS (Flexible AC Transmission System) controller. By adding a STATCOM (Static synchronous Shunt Converter) at the front end of the test power system and connecting to the common DC link of the IPFC, it is possible to bring the power factor to higher level and harmonics to the lower level and this arrangement is popularly known as Generalized Inter line power flow controller (GIPFC). In this paper a new concept of GIPFC based on incorporating a voltage source converter with zero sequence injection SPWM technique is presented for reinforcement of system stability margin. A detailed circuit model of modified GIPFC is developed and its performance is validated for a standard test system. Simulation is done using MATLAB Simulink.Index Terms—Convertible static controller, Flexible AC Transmission System (FACTS), Generalized Interline Power Flow Controller (GIPFC),STATCOM, SSSC, Reactive power compensation.
13
Zhang, Yifan, Fei Tang, Fanghua Qin, Yu Li, Xin Gao, and Nianchun Du. "Research on Dynamic Reactive Power Compensation Scheme for Inhibiting Subsequent Commutation Failure of MIDC." Sustainability 13, no. 14 (July 13, 2021): 7829. http://dx.doi.org/10.3390/su13147829.
Анотація:
Commutation failure at the inverter side of an MIDC (multi-infeed HVDC) is usually caused by AC system faults. Suppose the converter bus voltage cannot recover to the normal operation level in time: in that case, the commutation failure will then develop into more severe subsequent commutation failures or even DC blocking, which will severely threaten the security and stability of the system. Dynamic reactive power compensation equipment (DRPCE) can offer voltage support during accident recovery, stabilize voltage fluctuation and inhibit any subsequent commutation failure risk. This paper proposes the optimal DRPCE configuration scheme for maximizing both inhibitory effect and economic performance. The simulation results on MATLAB-BPA prove the scheme’s correctness and rationality, which can effectively inhibit the risk of subsequent commutation failure and obtain economic benefits.
14
Jun Yu. "Establishment and Optimization of Security Domain Prevention System in Business Middle Office Based on Choquet Expectation." Journal of Electrical Systems 20, no. 6s (April 29, 2024): 3063–69. http://dx.doi.org/10.52783/jes.3720.
Анотація:
With the rapid development of China's national economy, the needs of People's Daily life are increasing, and the demand for various business middle platform security domain prevention is also increasing.At the same time, due to the imbalance of its own resource allocation, it shows the characteristics of "more resources and less load" in the western region.With the gradual popularization of the application of Choquet expectation, a large number of new Choquet expectation algorithms have been incorporated into the security domain prevention system of the business middle platform, and have entered thousands of households.This kind of distributed generation also has its own problems such as difficulties in grid connection, large amount, small environmental pollution, flexible operation mode, and prominent stability problems.Factors such as the interconnection of large-area services, long-distance transmission of AC and DC UHV, and marketization of services make the topology of services more complicated, and the steady-state operation of Choquet services is also closer to the critical stable operation point.At present, the security domain prevention of China's business middle office has become a serious problem.In recent years, there have been several large-scale business middle office security domain incidents around the world.A comprehensive study of the above business middle platform security domain prevention events shows that when the business load is heavy and the business is complex, when the business has a large fault, it will lead to the chain short circuit of the business and serious economic damage.Therefore, combining Choquet expectation to quickly and accurately consider the stability of the service, and combining the new energy characteristics, especially the characteristics of Choquet expectation, is the main problem and problem of the security domain prevention market in the future business.
15
Jun Yu. "Establishment and Optimization of Security Domain Prevention System in Business Middle Office Based on Choquet Expectation." Journal of Electrical Systems 20, no. 6s (May 2, 2024): 2327–33. http://dx.doi.org/10.52783/jes.3211.
Анотація:
With the rapid development of China's national economy, the needs of People's Daily life are increasing, and the demand for various business middle platform security domain prevention is also increasing.At the same time, due to the imbalance of its own resource allocation, it shows the characteristics of "more resources and less load" in the western region.With the gradual popularization of the application of Choquet expectation, a large number of new Choquet expectation algorithms have been incorporated into the security domain prevention system of the business middle platform, and have entered thousands of households.This kind of distributed generation also has its own problems such as difficulties in grid connection, large amount, small environmental pollution, flexible operation mode, and prominent stability problems.Factors such as the interconnection of large-area services, long-distance transmission of AC and DC UHV, and marketization of services make the topology of services more complicated, and the steady-state operation of Choquet services is also closer to the critical stable operation point.At present, the security domain prevention of China's business middle office has become a serious problem.In recent years, there have been several large-scale business middle office security domain incidents around the world.A comprehensive study of the above business middle platform security domain prevention events shows that when the business load is heavy and the business is complex, when the business has a large fault, it will lead to the chain short circuit of the business and serious economic damage.Therefore, combining Choquet expectation to quickly and accurately consider the stability of the service, and combining the new energy characteristics, especially the characteristics of Choquet expectation, is the main problem and problem of the security domain prevention market in the future business.
16
Zamudio, M. A., A. M. Carhuavilca, L. A. Conde, M. A. García, A. E. Berastain, J. Montes-Romero, J. De la Casa, J. A. Töfflinger, and M. A. Cataño. "Development of a low-cost monitoring system for the measurement of DC and AC electrical parameters in grid-connected photovoltaic systems based on IEC standards." Journal of Physics: Conference Series 2538, no. 1 (June 1, 2023): 012004. http://dx.doi.org/10.1088/1742-6596/2538/1/012004.
Анотація:
Abstract The rapid development of renewable energy sources, such as photovoltaic solar energy, makes it possible to sustainably cover part of the energy demand in different parts of the world. Thus, higher efficiency of photovoltaic systems is sought to provide higher yields, security, and stability in their operation and energy production. Therefore, it is crucial to monitor the variables of interest and verify the correct operation of photovoltaic systems. This article presents the development of a monitoring system that allows the acquisition and recording of the main electrical parameters, both in direct and alternating current, enabling the evaluation of the array and final yield of grid-connected photovoltaic systems. The developed monitoring system follows the concept of the Internet of Things for remote data analysis. In addition, it allows local data logging in a computer for data acquisition over a long period. The measurements of the developed monitoring system comply with the International Electrotechnical Commission standards specified in IEC 61724-1. This validation is performed after contrasting the measurements obtained by the developed system with those obtained by the high-precision WT5000 power analyzer, where the relative differences of each electrical parameter analysed are less than 2%. Finally, the system developed is characterised by its low cost, which is less than US$ 140.
17
Motjoadi, Vinny, Pitshou N. Bokoro, and Moses O. Onibonoje. "A Review of Microgrid-Based Approach to Rural Electrification in South Africa: Architecture and Policy Framework." Energies 13, no. 9 (May 2, 2020): 2193. http://dx.doi.org/10.3390/en13092193.
Анотація:
Access to electricity for every South African citizen, including rural dwellers, is a human right issue guaranteed by the government’s laws and policies. However, many remote rural areas still suffer from a lack of this very important amenity, due to the expensive prospect of connecting them to the central national grid. The feasible approach to connecting the rural communities to electricity supply is suggestively through the use of microgrid solutions. The microgrid technology is a very recent and viable option for the energy revolution. Microgrids result from the incorporation of energy storage systems, distributed generators, and localized loads. The application of this technology requires deliberate and extensive work on the operational architecture and the policy framework to be adopted. The energy storage devices form an integral part of the microgrid configuration or architecture to make sure more maintainable and constant operation is attained. This paper presents a review of the architectures of the existing microgrid systems, as well as the policy framework for implementable solutions. The various architectures display the peculiarity of the systems based on the increased grid performance, stability, quality of electricity, and other comparative advantages. The microgrid architectures are fundamentally recognized according to their AC, DC, or hybrid distribution buses and the complexity inherent to them. In the Policy And Development Section, the problems are treated as ‘a search for the truth’—a truth being revealed by close and objective examination. The core of the problem to be solved is revealed clearly, thereby giving the basis for simplifying and solving it. The policies encourage the accomplishment of a zero-carbon dioxide (CO 2 ) emissions, energy security attainment, the meeting of the electricity demand, and, lastly, the promotion of access to electricity in rural areas. It is established that the returns through charges of the consumers are very insignificant. Although returns on investment always come in conflict with the human right demands of the local indigenes, the policy framework would be explicit on the mode of returns for the government, private partners, and the communities—a return that can be short, medium, or long term. Policymakers would be keen on the exhaustive analysis of issues, leading to optimal decision making.
18
Maya Utami Dewi, Sulartopo Sulartopo, and Ahmad Solechan. "REDUCING THE SHOOTING OF HYBRID PHOTOVOLTAIC PLANTS ON SCR AND LI-GRIDS." Journal of Technology Informatics and Engineering 1, no. 3 (December 22, 2022): 18–32. http://dx.doi.org/10.51903/jtie.v1i3.147.
Анотація:
The main threat by comparable methods lately is the temporary downtime for accurate-current network dispatch errors. Throughout a temporary outage, Power Electronic based power sources stop operating, giving rise to possible security defiance towards the network, in this research, the potentially viable choice to serve continuous work temporarily for the scheme is provided with consideration of identifying upgrades to existing photovoltaic generators (photovoltaic generators discrete) and an upgrade in the separate establishment of existing “photovoltaic” and “Energy Storage Systems” discrete hybrid photovoltaics. This study aims to find a series of power sources with Power Electronic interfaces that are connected to a low “Short Circuit Ratio” network and “Low Inertia” grid to operate without a moment's stoppage.
The proposed method was proved by adopting PSS/e on a method where power electronics-occupying assets produce the majority of energy. Inverter models along with temporary shutdown through an equal 3-period fault were advanced in PSS/e. together with increasing infiltration of “Power Electronics” established multitude and resources, progressive completion is needed to improve network stability in low a) areas and low inertia networks. The requirements for progressive solvent arose out of the steady variation in the paradigm of the power grid from the dominant systems of traditional electric machines to the high penetration of systems based on power electronics. A technical comparison was made between distinct categories of resolution (divergent photovoltaic and divergent hybrid photovoltaic) to operate a photovoltaic generator's weak “Short Circuit Ratios” also “Low Inertia” grating (grid).
The results of this study indicate that the proposed solution is calculated nether disparate running term and error class adopting the Electromagnetic Transient model. Moreover, to analyze distinct solvents, a specialized proportion is served on discrete hybrid photovoltaic generators. The proposed solution is the development of conventional increase as well as contemporary condensers, deter capacitors, and reducers to advanced photovoltaic generators and hybrid photovoltaic generators to provide voltage support to ensure continuous working through lopsided dispatch streak disturbances, and another solution is photovoltaic-energy generation. Integrated storage system connected to High Voltage dc and high voltage ac transmission network.
19
Ni, Hui Jun. "AC-DC-AC Frequency Control System Simulation Analysis." Applied Mechanics and Materials 536-537 (April 2014): 1110–13. http://dx.doi.org/10.4028/www.scientific.net/amm.536-537.1110.
Анотація:
Asynchronous motor various start models was analyzed through Mat-lab programming. With analysis on AC-DC-AC inverter startup simulation model, the results show inverter startup has advantages of startup time shortened, good stability, and quick convergence.
20
Hong, Yuan Xin, and Guang Qing Bao. "Emergency Power Support and Voltage Stability Analysis of the AC/DC Hybrid Transmission System." Advanced Materials Research 614-615 (December 2012): 1033–37. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.1033.
Анотація:
With the completion of Three Gorges Project, the power system in China is forming a huge AC/DC network. In the hybrid AC/DC parallel transmission system, a line fault will cause fluctuations even crash of the system. The HVDC transmission system based on the emergency DC power support (EDCPS) can provide a fast emergency power support for the interconnected AC power grid flexibly and improve the stability of AC power. A model of AC/DC hybrid transmission system is established in the PSCAD/EMTDC simulation environment. An improved PID controller is firstly introduced to the hybrid AC/DC transmission system. The simulation result shows the EDCPS has an obvious effect on keeping the voltage stability of the system.
21
Bakeer, Abualkasim, Andrii Chub, Abderahmane Abid, Sherif A. Zaid, Thamer A. H. Alghamdi, and Hossam S. Salama. "Enhancing Grid-Forming Converters Control in Hybrid AC/DC Microgrids Using Bidirectional Virtual Inertia Support." Processes 12, no. 1 (January 5, 2024): 139. http://dx.doi.org/10.3390/pr12010139.
Анотація:
This paper presents a new grid-forming strategy for hybrid AC/DC microgrids using bidirectional virtual inertia support designed to address weak grid conditions. The stability of hybrid AC/DC microgrids heavily relies on the AC mains frequency and the DC-link voltage, and deviations in these factors can lead to undesirable outcomes such as load curtailments and power system congestions and blackouts. This paper introduces a unique approach that leverages bidirectional virtual inertia support to enhance the stability and reliability of hybrid AC/DC microgrids under weak grid conditions. The proposed strategy employs virtual inertia as a buffer to mitigate rapid changes in DC-link voltage and AC frequency, thereby enhancing system stability margins. This strategy significantly contributes to a more stable and reliable grid operation by reducing voltage and frequency fluctuations. A standard hybrid AC/DC microgrid configuration is used to implement the bidirectional virtual inertia support, where a bidirectional interlinking converter control is adjusted to deliver inertia support to both the AC and DC subgrids. This converter utilizes the DC grid voltage and AC grid frequency as inputs, effectively managing active power balance and implementing auxiliary functions. Extensive simulations are conducted under weak grid conditions and standalone mode to validate the effectiveness of the proposed strategy. The simulation results demonstrate a remarkable improvement in frequency nadir, rate-of-change-of-frequency (RoCoF), and DC bus voltage deviation in the hybrid AC/DC microgrids. The bidirectional virtual inertia support substantially reduces voltage and frequency fluctuations, enhancing the microgrid stability and resilience. There is an improvement of over 45% and 25% in the frequency deviation and voltage deviation, respectively, achieved through implementing the proposed control strategy.
22
Ibrahim, Ahmad Asrul, Behzad Kazemtabrizi, and Javier Renedo. "Security-Constrained Day-Ahead Operational Planning for Flexible Hybrid AC/DC Distribution Networks." Applied Sciences 9, no. 21 (November 3, 2019): 4685. http://dx.doi.org/10.3390/app9214685.
Анотація:
A new active network management framework is presented based on a multi-period optimal power flow problem that is bounded by security constraints at the distribution level for upholding the security of supply. This can be achieved through active engagement with flexible demand and distributed generation to prepare for contingency events in day-ahead operational planning. This framework is coupled with a flexible hybrid AC/DC medium voltage (MV) distribution network topology. It contains an integrated multi-terminal medium voltage DC (MVDC) interface for a seamless interaction and integration of the flexible demand and generation on both AC and DC sides of the hybrid network. The active energy management framework when coupled with a flexible hybrid AC/DC topology provides unprecedented degrees of flexibility as well as security of operation under a variety of conditions. To this end, the 75-bus UK generic distribution network has been modified and converted into a hybrid AC/DC network using the integrated MVDC interface. This framework is then deployed to minimise operational costs to the network operator, considering costs of schemes such as distributed generation curtailment and flexible demand shifting, as well as network losses. Results show a significant improvement in operational costs when the network operates as a flexible hybrid when compared to a pure AC or a more conventional AC/DC hybrid.
23
Pedra, Joaquín, Luis Sainz, and Lluís Monjo. "DC Admittance Model of VSCs for Stability Studies in VSC-HVDC Systems." Energies 16, no. 14 (July 18, 2023): 5457. http://dx.doi.org/10.3390/en16145457.
Анотація:
High-voltage direct current (HVDC) systems linked to AC grids with converters are promising energy transmission systems. These systems present complex AC- and DC-side dynamic interactions. Impedance-based stability studies have recently been proposed to assess DC-side dynamics from DC-side characterization of voltage source converters (VSCs) considering AC-side dynamics. However, the existing approaches used for stability studies in VSC-HVDC systems do not completely model VSCs because they do not consider together the VSC delay, the grid voltage feedforward filter, and all the d- and q-reference current controls. Moreover, these approaches are analytically characterized from dq-real space vectors (less related to circuit theory than dq-complex space vectors), and some work with simple AC grids. The main contribution of this paper is a detailed and complete DC admittance model of VSCs from dq-complex space vectors, which considers the VSC delay, feedforward filter, and d- and q-reference current controls, and also a general AC grid. The proposed model can be used for DC-side stability studies in VSC-HVDC systems considering AC grid dynamics. The capabilities and drawbacks of impedance-based stability methods for DC-side stability assessment were analyzed, and the positive-net-damping criterion was validated as a robust approach. The model was validated by PSCAD/EMTDC simulations and applied to a stability study in a VSC-HVDC system.
24
Liu, Xiao Ming, Xin Sheng Niu, Jun Li Xiao, and Jie Zhang. "Influence of AC System Strength on Voltage Stability of DC Receiving-End Power Grid." Applied Mechanics and Materials 380-384 (August 2013): 3013–17. http://dx.doi.org/10.4028/www.scientific.net/amm.380-384.3013.
Анотація:
The AC system strength at DC receiving-end exerts great influences on the voltage stability of power grid. The selected DC control modes and reactive power compensation mode should fit with the AC system strength at receiving end. This paper analyzes the influences of AC system strength at DC receiving-end on voltage stability of power grid from the point of mechanism, and conducts simulations based on Shandong power grid.
25
Liu, Xinbo, Shi Wang, Xiaotong Song, and Jinghua Zhou. "Stability Control Strategies for Bidirectional Energy Storage Converters Considering AC Constant Power Loads." Electronics 12, no. 4 (February 20, 2023): 1067. http://dx.doi.org/10.3390/electronics12041067.
Анотація:
In islanded AC microgrids, negative impedance characteristics of AC constant power loads (AC CPLs) easily introduce large signal instability to the system, while energy storage systems sometimes compensate for the dynamic characteristics of AC CPLs, and increase the system stability. Although energy storage control techniques and characteristics have gained a lot of attention, few studies have derived quantitative design guidelines for energy storage systems from the aspect of stability improvement. In order to fill this gap, this paper proposes stability control strategies for bidirectional energy storage converters considering the characteristics of AC CPLs to guarantee large signal stability of islanded AC microgrids. The presented control techniques create quantitative limits for the DC bus voltage loop control parameters of the energy storage DC/DC converter and the integral control loop control parameter of the energy storage DC/AC converter, and also interpret the positive stability influence of energy storage systems and the negative stability influence of AC CPLs. The structure of the paper is as follows. Firstly, DQ coordinate transformation is adopted, and AC microgrid nonlinear models with the energy storage system in charging and discharging states are constructed. Then, large signal models are constructed depending on mixed potential theory. Stability control strategies for bidirectional energy storage converters are obtained, and AC CPLs power, storage system equivalent resistor, and micro power source power are all taken into account. Finally, based on simulation and experimental results, it is obvious that regulating the control parameters of the energy storage converter significantly increases the large signal stability of islanded AC microgrids without extra equipment. The method is very simple and easy to implement.
26
Ge, Huiyang, Hongbin Sun, and Bin Wang. "Multi-scale AC−DC system voltage security regions." Journal of Engineering 2019, no. 16 (March 1, 2019): 3354–58. http://dx.doi.org/10.1049/joe.2018.8592.
27
Das, Soumya Ranjan, Alok Kumar Mishra, Prakash Kumar Ray, Surender Reddy Salkuti, and Seong-Cheol Kim. "Application of Artificial Intelligent Techniques for Power Quality Improvement in Hybrid Microgrid System." Electronics 11, no. 22 (November 21, 2022): 3826. http://dx.doi.org/10.3390/electronics11223826.
Анотація:
The hybrid AC-DC microgrid (MG) has gained popularity recently as it offers the benefits of AC and DC systems. Interconnecting AC-DC converters are necessary since the MG has both DC and AC sub-grids. Adding an extra harmonic adjustment mechanism to the interlinking converters is promising because non-linear AC loads can worsen the quality of the voltage on the AC bus. The interlinking converters’ primary function is to interchange real and reactive power between DC and AC sub-grids, so the typical harmonic controlling approach implemented for active power filters (APFs) might not be appropriate for them. When the MG’s capacity is high, it is desirable that the switching frequency be lesser than the APFs. The performance of harmonic correction or even system stability may suffer at low switching frequencies. In this study, a harmonic compensating technique appropriate for hybrid AC-DC interlinking converters with lower switching frequencies is planned. The suggested strategy, modeling techniques, stability analysis, and a thorough virtual impedance design are discussed in this work.
28
Guan, Chao Jie, Jin Quan Zhao, Jian Hua Yin, Kun Men, and Chao Hong. "Geometric Parameterization Technique Based Continuation Power Flow and its Applications in AC/DC Hybrid Power System." Advanced Materials Research 732-733 (August 2013): 857–63. http://dx.doi.org/10.4028/www.scientific.net/amr.732-733.857.
Анотація:
A new continuation power flow method based on local geometric parameterization technique is proposed for voltage stability analysis of AC/DC hybrid power system. By means of the alternating iteration method as the AC/DC power flow algorithm, the proposed method takes the coupling relationship between AC and DC systems into account to modify Jacobian matrix of AC system. Constraints of variables in DC system are also considered, as well as the adjustment of converter transformers tap position and the conversion of converters control modes. Based on the predictor-corrector method, this paper adopts the geometric corrector, and changes the direction of convergence effectively. According to different operation modes of AC/DC system, accurate voltage stability limit and the entire PV curve can be acquired. Simulation results of IEEE test systems are used to show the validity of the proposed algorithm.
29
Liu, Xinbo, Zhenkang Zhu, Junfu Shi, Xiaotong Song, and Jinghua Zhou. "Large Signal Stability Criteria Combined with a 3D Region of Asymptotic Stability Method for Islanded AC/DC Hybrid Microgrids." Electronics 11, no. 23 (December 5, 2022): 4042. http://dx.doi.org/10.3390/electronics11234042.
Анотація:
Large disturbances frequently happen in isolated AC/DC Hybrid Microgrids. Unfortunately, constant power loads (CPLs) with negative impedance characteristics are equivalent to positive feedback, resulting in an increase in large disturbances. The system can easily become unstable. Consequently, large signal stability criteria are proposed in this paper. Combined with a three-dimensional region of asymptotic stability (3D RAS) method for islanded AC/DC Hybrid Microgrids, important parameters to increase stability margins were determined. Firstly, mixed potential theory was used to derive a large-signal stability criterion. The criteria gave constraints on filtering parameters, CPL power, power of the battery to charge and discharge, AC resistive loads, and DC bus voltage. Then, Lyapunov functions were constructed, and the Lasalle invariance principle was adopted to achieve 3D RAS. When large disturbances emerged, and simultaneously voltage and current varied in 3D RAS, the system always obtained stability and reached new steady-state equilibrium points. Finally, according to comparisons, bigger capacitances of the DC bus capacitor and the AC capacitor, larger battery discharging power and smaller charging power could significantly increase stability margins of islanded Microgrids. Simulations and experimental data have shown that the large signal stability criteria and the 3D RAS work.
30
Fu, Hong Jun, Jian Hua Sun, Jing Gang Wang, and Yang Yu Hu. "The Static Voltage Stability Limit Calculation of AC/DC Hybrid Power System Based on Improved Continuation Power Flow Algorithm." Applied Mechanics and Materials 347-350 (August 2013): 1450–54. http://dx.doi.org/10.4028/www.scientific.net/amm.347-350.1450.
Анотація:
With the HVDC system interconnected to power grid, the voltage stability problem of power grid has become increasingly prominent. This paper establishes the mathematical model of AC/DC hybrid power system and proposed an improved Continuation Power Flow (CPF) algorithm to calculate the static voltage stability limit of AC/DC hybrid system, the characteristics of this algorithm are as following: PQ decoupled power flow algorithm is used; Lagrange quadric interpolation is used in the process of predictor and step control; local parameter method is used in the correction. The iterations of AC/DC calculation alternate to solve power flow equations and select the step control near the critical power limit points to ensure the convergence of power flow solution. In order to verify the correctness of the proposed algorithm, this paper compares the calculation results by the improved algorithm and Matpower on the IEEE 14 bus-system. This paper calculates the static voltage stability limit of AC/DC hybrid power system under different DC control patterns of modified IEEE 14 bus-system and analyzes the impacts of different DC control pattern to the system voltage stability.
31
Li, Fang, and Xing Lei Chen. "Research on Impacts of FACTS on Static Voltage Stability Characteristics of AC/DC Power System." Applied Mechanics and Materials 347-350 (August 2013): 1440–44. http://dx.doi.org/10.4028/www.scientific.net/amm.347-350.1440.
Анотація:
Based on the improved Continuation Power Flow algorithm, this paper investigates the impacts of FACTS on static voltage stability characteristics of AC/DC hybrid power system. This paper introduces the steady-state model of different FACTS devices, and the power flow mathematical model is established about AC/DC power system with FACTS devices. The impacts of FACTS devices with various capacities in different locations on static voltage stability are compared and analyzed. The calculation results of a four-machine two regions AC/DC power system show that FACTS are able to improve the voltage stability and the installation of SVC shunt compensation can possess a better effect to improve the system static voltage stability limit than TCSC series compensation.
32
Chang, Fangyuan, John O’Donnell, and Wencong Su. "Voltage Stability Assessment of AC/DC Hybrid Microgrid." Energies 16, no. 1 (December 29, 2022): 399. http://dx.doi.org/10.3390/en16010399.
Анотація:
AC/DC hybrid microgrids are becoming potentially more attractive due to the proliferation of renewable energy sources, such as photovoltaic generation, battery energy storage systems, and wind turbines. The collaboration of AC sub-microgrids and DC sub-microgrids improves operational efficiency when multiple types of power generators and loads coexist at the power distribution level. However, the voltage stability analysis and software validation of AC/DC hybrid microgrids is a critical concern, especially with the increasing adoption of power electronic devices and various types of power generation. In this manuscript, we investigate the modeling of AC/DC hybrid microgrids with grid-forming and grid-following power converters. We propose a rapid simulation technique to reduce the simulation runtime with acceptable errors. Moreover, we discuss the stability of hybrid microgrids with different types of faults and power mismatches. In particular, we examine the voltage nadir to evaluate the transient stability of the hybrid microgrid. We also design a droop controller to regulate the power flow and alleviate voltage instability. During our study, we establish a Simulink-based simulation platform for operational analysis of the microgrid.
33
González, Jorge Wilson, Mohammed Rashwan, Hugo Alberto Cardona, Idi Amín Isaac, and Gabriel Jaime López. "Proposal of indexes for fast voltage stability evaluation of ac/dc transmission systems." Revista Facultad de Ingeniería Universidad de Antioquia, no. 59 (December 4, 2012): 219–26. http://dx.doi.org/10.17533/udea.redin.13826.
Анотація:
This paper develops voltage stability analysis of ac/dc systems using static and modal indexes. New indexes treatment is proposed to provide more information on requirements for specific network strengths in terms of voltage stability constituting a means to prevent potential issues of high voltage dc transmission system (HVdc), connected to weak ac nodes. The indexes are per unitized and compared for different short circuit ratios (SCR), in a modified IEEE 14 buses network, with a HVdc system connected to its weakest bus. The approach can assist as much for planning as for on-line monitoring of voltage stability in power systems including ac/dc nodes.
34
Zhao, Caiping, and Qiyuan Wang. "Influence of DC transmission distance on MMC-HVDC stability under weak AC system." Journal of Physics: Conference Series 2290, no. 1 (June 1, 2022): 012024. http://dx.doi.org/10.1088/1742-6596/2290/1/012024.
Анотація:
Abstract The oscillation problem of MMC-HVDC under weak AC system poses a potential threat to the safe and stable operation of power grid, which is related to both of the AC and DC parameters. By comparing the stability of MMC-HVDC under different AC system strength with different DC transmission distance, it is found that when the AC system strength is too weak, there is a risk of instability under the condition of long DC transmission distance, and the correctness of this conclusion is verified by time-domain simulation. Later, the mechanism analysis of this phenomenon is carried out, the result shows that it is related to the interaction of MMC subsystems when the strength of AC system decreases.
35
Wu, Xiong, Zhao Wang, Tao Ding, and Zhiyi Li. "Hybrid AC/DC Microgrid Planning with Optimal Placement of DC Feeders." Energies 12, no. 9 (May 9, 2019): 1751. http://dx.doi.org/10.3390/en12091751.
Анотація:
With the significant increase in DC loads (such as data and telecommunication centers) at the power distribution level, an additional set of power electronic converters are required to connect these DC loads to the AC-dominant power network. Notably, hybrid AC/DC microgrids (MGs) serve as promising solutions to satisfying both the AC and DC loads with a reduced number of installed converters. Since DC loads may be randomly distributed in the MG, how to place DC feeders to simultaneously fulfill the economic and security requirements of MG operations remains a challenging problem. To address this issue, this paper proposes a hybrid AC/DC MG planning model to determine the optimal placement of DC feeders with the objective of minimizing the total cost of the investment of distributed energy resources (DERs), converters, and AC/DC distribution lines, as well as the operation of DERs. In particular, the power flow of the hybrid AC/DC MG is derived in a unified manner and then incorporated in the planning model. Eventually, the proposed model suffices to find the optimal number and siting for both DERs and DC feeders while ensuring the continuality of the DC feeders. The proposed model is tested in two MG-based distribution systems, and its effectiveness is validated by the results of numerical experiments.
36
Fernandopulle, Nilkamal, and Robert Alden. "Domain of stability of ac/dc power systems." Canadian Journal of Electrical and Computer Engineering 32, no. 4 (2007): 215–20. http://dx.doi.org/10.1109/cjece.2007.4407668.
37
Liu, Jian Tao, Chen Long Li, and Ke Wang. "Study of the Emergency DC Power Support Strategy Based on the Principles of the Generalized Dynamics." Advanced Materials Research 732-733 (August 2013): 719–25. http://dx.doi.org/10.4028/www.scientific.net/amr.732-733.719.
Анотація:
Emergency HVDC power support (EDCPS) can be used for improving the transient stability of AC/DC power systems, but the effect is directly determined by the quantity, the starting time, the speed and other factors of the power support. In this article, the dynamic characteristics of AC/DC power systems after a fault are analyzed, generalized dynamical models of the AC/DC power system are established, the relationship between the duration and the quantity of the EDCPS and the dynamic characteristics of the system are established based on the impulse theorem, then the EDCPS strategy besed on the principles of the generalized dynamics is proposed. At last, it is verified by examples of simulation that the strategy can effectively improve the stability of the AC/DC power systems after a fault.
38
Wang, Zonghao, and Liying Sun. "Design of voltage stabilizing control for a hybrid microgrid with state constraints based on the switching system." Journal of Physics: Conference Series 2474, no. 1 (April 1, 2023): 012067. http://dx.doi.org/10.1088/1742-6596/2474/1/012067.
Анотація:
Abstract With the application and development of new energy generation technology and distributed power supply system, AC-DC hybrid microgrid has the comprehensive advantages of AC microgrid and DC microgrid, and it is significant to study the voltage stability of hybrid microgrid. Based on the switching system theory, the voltage stability control of the ac-dc hybrid micro-grid in grid-connected and the off-grid operation mode are studied in this paper. Considering that the AC and DC bus voltages of the microgrid are constrained in practical engineering applications, the Backstepping controller is designed by using the barrier Lyapunov function and Backstepping method. Considering that the equivalent resistance in the system can not be accurately measured and combined with adaptive control, it is more practical for practical engineering applications.
39
Dhivya, K. T., and Dr K. Yasoda. "Implementation of ANN Controller Based Interleaved Hybrid Converter." International Journal for Modern Trends in Science and Technology 6, no. 6 (June 30, 2020): 178–81. http://dx.doi.org/10.46501/ijmtst060632.
Анотація:
In existing method separate DC-DC and DC-AC converter topologies are required to supply DC and AC loads in which efficiency is poor. In the proposed work single converter topology of interleaved hybrid converter is used to provide simultaneous AC and DC output. Battery is used to supply load in absence of solar power. Artificial Neural Network control strategy is used to provide gating signals for the converter which improves the overall performance and stability of the system.AC and DC output from the interleaved hybrid converter are obtained using MATLAB/Simulink
40
Lotfjou, A., M. Shahidehpour, Yong Fu, and Zuyi Li. "Security-Constrained Unit Commitment With AC/DC Transmission Systems." IEEE Transactions on Power Systems 25, no. 1 (February 2010): 531–42. http://dx.doi.org/10.1109/tpwrs.2009.2036486.
41
Shen, Li, Li Jiang, Qing Wang, Yiyu Wen, and Tingjian Liu. "Multi-Period Transmission Expansion Planning for Renewables-Rich Power Grid Enabling Transfer Capacity Enhancement of Hybrid AC/DC Interface." Energies 16, no. 5 (February 23, 2023): 2170. http://dx.doi.org/10.3390/en16052170.
Анотація:
With the increasing integration of HVDC tie-lines, the regional power systems in both the energy-exporting area and the energy-importing area have been gradually evolving into “strong DC, weak AC” systems. In this paper, a multi-period transmission expansion planning optimization model is proposed for an energy-exporting power grid with hybrid AC/DC interface. While the existing literature has not considered the dynamic security problem in TEP, this paper adopts the conventional total transfer capacity (TTC) index to evaluate the security limit of hybrid AC/DC interface under different transmission expansion schemes. Multiple objectives are considered to reduce the investment cost while promoting the consumption of renewables by enhancing the total transfer capacity of hybrid AC/DC interface. The non-dominated sorting genetic algorithm-II (NSGA-II) is used to compute the optimal solution for the proposed multi-period multi-objective transmission expansion planning problem. A case study on the modified IEEE 39-bus system is presented to demonstrate the effectiveness of the proposed method.
42
Liu, Xiao Ming, Xin Sheng Niu, Yan Wang, and Jun Li Xiao. "Research on Stability of Voltage of AC&DC Hybrid System." Applied Mechanics and Materials 380-384 (August 2013): 2967–71. http://dx.doi.org/10.4028/www.scientific.net/amm.380-384.2967.
Анотація:
DC transmission brings in pressure on the supporting capacity of voltage of AC system along with its more and more wide application. Under the steady state, the reactive power consumed in the process of commutation in the converter station is equivalent to a half of that for transmission of active power. During the failure and in course of system recovery after removal of failure, there may be more reactive power to be consumed because of the regulation function of controller. A number of studies on the stability of voltage of AC/DC system have been conducted at home and abroad. This paper summarizes the research methods of the stability of voltage of AC&DC hybrid system.
43
Li, Chenghao, Di Zhang, Zhiwei Liu, Yulong Xiong, Tianhang Yu, Ze Gao, and Shihong Miao. "An Evaluation Method of Renewable Energy Resources’ Penetration Capacity of an AC-DC Hybrid Grid." Energies 15, no. 7 (March 31, 2022): 2550. http://dx.doi.org/10.3390/en15072550.
Анотація:
With increasingly more renewable energy being integrated into the AC-DC hybrid grid, the grid shows more complex dynamic characteristics due to the mutual coupling of HVDC and renewable energy. To evaluate the renewable energy resources’ penetration capacity of the AC-DC hybrid grid, this paper proposes an evaluation method of the renewable energy resources’ penetration capacity of an AC-DC hybrid grid, which considers both economy and safety. Firstly, indicators are proposed for an evaluation of the economy and safety of the AC-DC hybrid grid integrated with renewable energy, where both static and transient stability indicators are considered. Secondly, to maximize the renewable energy penetration capacity and minimize the network loss, an optimization model of the renewable energy penetration capacity of the AC-DC hybrid grid is established considering the static and transient stability constraints. Then, a heuristic solution method for solving the renewable energy penetration capacity optimization model is proposed. Finally, based on the improved IEEE 39 node system, a case analysis is carried out. The simulation results verify the correctness and effectiveness of the proposed method.
44
Yan, Zheng, and Jianyuan Xu. "Sequence Impedance Modeling and Analysis of Modular Multilevel Converter Considering DC Port Characteristics." Energies 16, no. 23 (November 25, 2023): 7770. http://dx.doi.org/10.3390/en16237770.
Анотація:
The extensive deployment of Modular Multilevel Converters (MMCs) in AC/DC systems can lead to complex resonance issues. Impedance modeling forms the foundation for analyzing the stability of interconnected system. Existing investigations primarily address resonance concerns on the AC side of MMC. In the process of impedance modeling, the DC system is generally approximated as an ideal voltage source, thereby neglecting its dynamic impact on the impedance characteristic of MMC. Such simplification may result in inaccuracies within stability analysis findings. Based on the multi-harmonic linearization method, this paper introduces an impedance modeling approach that takes into account the characteristics of the DC port. Taking DC voltage control as a case study, the impedance model for the AC side of the MMC is established. The results of programming calculation and simulation measurement of sequence impedance are mutually verified. Finally, the MMC impedance responses determined by different DC port characteristics are analyzed. Significant alterations in MMC impedance characteristics are introduced by DC side resistance and capacitance, which may result in negative damping effects and a decrease in system stability margins. The DC side inductance has a relatively minor impact on MMC impedance responses. The analysis results show that the sequence impedance model of MMC considering DC port characteristics can improve the accuracy of stability analysis results.
45
Tada, Yasuyuki, Akihiko Yokoyama, and Yasuji Sekine. "Influence of AC-DC parallel interconnection on voltage stability of AC systems." Electrical Engineering in Japan 112, no. 4 (1992): 74–84. http://dx.doi.org/10.1002/eej.4391120408.
46
Wang, Jing Biao, Xi Wang Abuduwayiti, Qin Chao, and Qing Luo. "Modal Research on the Low-Frequency Oscillation of AC/DC System with DFIG-Based Wind Farms." Applied Mechanics and Materials 672-674 (October 2014): 331–36. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.331.
Анотація:
Low-frequency oscillation characteristics of AC / DC system with DFIG-based wind farms were studied. Detailed mathematical pure AC and AC / DC system model were established by considering the effects of doubly-fed wind turbine model and DC transmission dynamic model to do small signal stability analysis. The computed results of small signal stability of DFIG-based wind farms integrating pure AC CEPRI36 nodes system or with DC transmission that operated in four connection modes including bipolar neutral grounding at both ends mode, monopole ground return mode, monopole metallic return mode , monopole and two parallel conductor mode with earth return were investigated by using modal analysis method. Then, the characteristics of local oscillation modes and inter-area oscillation modes were respectively analyzed under the two operation modes of the wind farm participating active power dispatching and reactive power dispatching and consequently some new conclusions were drawn.
47
Aljafari, Belqasem, Subramanian Vasantharaj, Vairavasundaram Indragandhi, and Rhanganath Vaibhav. "Optimization of DC, AC, and Hybrid AC/DC Microgrid-Based IoT Systems: A Review." Energies 15, no. 18 (September 18, 2022): 6813. http://dx.doi.org/10.3390/en15186813.
Анотація:
Smart microgrids, as the foundations of the future smart grid, combine distinct Internet of Things (IoT) designs and technologies for applications that are designed to create, regulate, monitor, and protect the microgrid (MG), particularly as the IoT develops and evolves on a daily basis. A smart MG is a small grid that may operate individually or in tandem with the electric grid, and it is ideal for institutional, commercial, and industrial consumers, as well as urban and rural societies. A MG can operate in two methods (stand-alone and grid-connected), with the ability to transition between modes due to local grid faults, planned maintenance, expansions, deficits and failures in the host system, and other factors. Energy storage is the process of storing and converting energy that can be used for a variety of purposes, including voltage and frequency management, power backup, and cost optimization. IoT is designed to deliver solutions for optimal energy management, security protocols, control methods, and applications in the MG, with numerous distributed energy resources (DER) and interconnected loads. The use of IoT architecture for MG operations and controls is discussed in this research. With the use of power grid equipment and IoT-enabled technology, MGs are enabling local networks to give additional services on top of the essential supply of electricity to local networks that operate simultaneously or independently from the regional grid. Additionally, this review shows how hybrid AC/DC MGs are advantageous compared to AC and DC MGs. The state-of-the-art optimization techniques and trends in hybrid MG research are included in this work.
48
Liu, Xinbo, Yake Zhang, Xiaotong Song, and Yuntao Ju. "Large Signal Stability Analysis of Hybrid AC/DC Microgrids When a Single-Phase-to-Ground Fault Occurs." Electronics 13, no. 7 (March 26, 2024): 1232. http://dx.doi.org/10.3390/electronics13071232.
Анотація:
Islanded hybrid AC/DC microgrids lack support for a large grid, and the negative incremental impedance of constant power loads (CPLs) aggravates the poor anti-disturbance capability of the system. When a single-phase ground fault (SPGF) occurs, the amount of fault impulse power that islanded AC/DC hybrid microgrids can stably withstand and when the protection equipment can work are both unknown. In this paper, the method of symmetrical components is utilized, and high-signal stability criteria for islanded hybrid AC/DC microgrids when a SPGF occurs are derived based on the mixed potential theory. The proposed criteria place quantitative constraints on the power of the PV unit, DC/AC converter current inner-loop proportional parameters, inductors, and inductor equivalent resistance, as well as energy storage unit power, CPL power, capacitors, DC bus voltage, line equivalent resistance, line equivalent inductance, equivalent inductance in the faulty branch, equivalent resistance in the faulty branch, positive-sequence equivalent impulse power of the SPGF, and zero-sequence equivalent impulse power. Furthermore, the maximum impulse power of a SPGF that islanded hybrid AC/DC microgrids could stably withstand is also presented, providing guidelines for protection equipment to decide when to work. In addition, the allowable maximum CPL power that islanded hybrid AC/DC microgrids could steadily support as a SPGF occurs is deduced, and the power is usually adopted to determine the states of an energy storage unit and load shedding in advance. Simulation and experimental validations prove the correctness of the derived high-signal stability criteria.
49
Kang, Jin-Wook, Ki-Woong Shin, Hoon Lee, Kyung-Min Kang, Jintae Kim, and Chung-Yuen Won. "A Study on Stability Control of Grid Connected DC Distribution System Based on Second Order Generalized Integrator-Frequency Locked Loop (SOGI-FLL)." Applied Sciences 8, no. 8 (August 16, 2018): 1387. http://dx.doi.org/10.3390/app8081387.
Анотація:
This paper studies a second order generalized integrator-frequency locked loop (SOGI-FLL) control scheme applicable for 3-phase alternating current/direct current (AC/DC) pulse width modulation (PWM) converters used in DC distribution systems. The 3-phase AC/DC PWM converter is the most important power conversion system of DC distribution, since it can boost 380 Vrms 3-phase line-to-line AC voltage to 700 Vdc DC output with various DC load devices and grid voltages. The direct-quadrature (d-q) transformation, positive sequence voltage extraction, proportional integral (PI) voltage/current control, and phase locked loop (PLL) are necessary to control the 3-phase AC/DC PWM converter. Besides, a digital filter, such as low pass filter and all pass filter, are essential in the conventional synchronous reference frame-phase locked loop (SRF-PLL) method to eliminate the low order harmonics of input. However, they limit the bandwidth of the controller, which directly affects the output voltage and load of 3-phase AC/DC PWM converter when sever voltage fluctuation, such as sag, swell, etc. occurred in the grid. On the other hand, the proposed control method using SOGI-FLL is able to do phase angle detection, positive sequence voltage extraction, and harmonic filtering without additional digital filters, so that more stable and fast transient control is achieved in the DC distribution system. To verify the improvement of the characteristics in the unbalanced voltage and frequency fluctuation of the grid, a simulation and experiment are implemented with 50 kW 3-phase AC/DC PWM converter used in DC distribution.
50
Sulaeman, Ilman, Gautham Ram Chandra Mouli, Aditya Shekhar, and Pavol Bauer. "Comparison of AC and DC Nanogrid for Office Buildings with EV Charging, PV and Battery Storage." Energies 14, no. 18 (September 14, 2021): 5800. http://dx.doi.org/10.3390/en14185800.
Анотація:
Future office buildings are expected to be integrated with energy intensive, inherently DC components such as photovoltaic panels (PV), electric vehicles (EV), LED lighting, and battery storage. This paper conceptualizes the interconnection of these components through a 750 V DC nanogrid as against a conventional three-phase 400 V AC system. The factors influencing the performance of a DC-based nanogrid are identified and a comparative analysis with respect to a conventional AC nanogrid is presented in terms of efficiency, stability, and protection. It is proved how the minimization of grid energy exchange through power management is a vital system design choice. Secondly, the trade-off between stability, protection, and cost for sizing of the DC buffer capacitors is explored. The transient system response to different fault conditions for both AC and DC nanogrid is investigated. Finally the differences between the two systems in terms of various safety aspects are highlighted.