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Liu, Jiayu, Min Tang, Jian Zhou, Qiqi Zhang i Luyuan Zhang. "A novel distributed secondary voltage control method for AC microgrids based on voltage observer". Journal of Physics: Conference Series 2237, nr 1 (1.03.2022): 012019. http://dx.doi.org/10.1088/1742-6596/2237/1/012019.
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Abstract Since the islanded AC Microgrid is affected by the impedance of line, it is difficult to coordinate the voltage regulation and reactive load distribution. A distributed secondary voltage controller based on observer is proposed for isolated AC Microgrids, and it does not need more voltage communications. This method can guarantee the estimated average voltage equals to average of actual output voltages that can converge to the nominal values, and realize accurate proportional load sharing in a microgrid. Then, the convergence of the voltage observer is proved. Finally, the proposed control method is verified by time-domain simulation.
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Liu, Weirong, Yu Song, Hongtao Liao, Heng Li, Xiaoyong Zhang, Yun Jiao, Jun Peng i Zhiwu Huang. "Distributed Voltage Equalization Design for Supercapacitors Using State Observer". IEEE Transactions on Industry Applications 55, nr 1 (styczeń 2019): 620–30. http://dx.doi.org/10.1109/tia.2018.2868539.
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Ghazzali, Mohamed, Mohamed Haloua i Fouad Giri. "Fixed-time observer-based distributed secondary voltage and frequency control of islanded AC microgrids". International Journal of Electrical and Computer Engineering (IJECE) 10, nr 5 (1.10.2020): 4522. http://dx.doi.org/10.11591/ijece.v10i5.pp4522-4533.
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This paper deals with the problem of voltage and frequency control of distributed generators (DGs) in AC islanded microgrids. The main motivation of this work is to obviate the shortcomings of conventional centralized and distributed control of micro-grids by providing a better alternative control strategy with better control performance than state-of-the art approaches. A distributed secondary control protocol based on a novel fixed-time observer-based feedback control method is designed for fixed-time frequency and voltage reference tracking and disturbance rejection. Compared to the existing secondary microgrid controllers, the proposed control strategy ensures frequency and voltage reference tracking and disturbance rejection before the desired fixed-time despite the microgrid initial conditions, parameters uncertainties and the unknown disturbances. Also, the controllers design and tuning is simple, straightfor-ward and model-free.i.e, the knowledge of the microgrid parameters, topology, loads or transmission lines impedance are not needed in the design procedure. The use of distributed control approach enhances the reliability of the system by making the control system geographically distributed along with the power sources, by using the neighboring DGs informations instead of the DG’s local informations only and by cooperatively rejecting external disturbances and maintaining the frequency and the voltage at their reference values at any point of the microgrid. The efficiency of the proposed approach is verified by comparing its performance in reference tracking and its robustness to load power variations to some of the works in literature that addressed distributed secondary voltage and frequency control.
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Yang, Chengshun, Tao Hua, Yuchen Dai, Guofu Liu, Xiaoning Huang i Dongdong Zhang. "Disturbance-Observer-Based Adaptive Fuzzy Control for Islanded Distributed Energy Resource Systems". Mathematical Problems in Engineering 2022 (3.02.2022): 1–12. http://dx.doi.org/10.1155/2022/1527705.
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With the aim to improve the antidisturbance ability of the islanded distributed energy resource (DER) systems, a disturbance-observer-based adaptive fuzzy sliding mode control (DAFSC) voltage controller is designed based on indirect vector control, which implements the voltage tracking and improves the self-regulation ability of the islanded DER systems. Firstly, the circuit diagram and the mathematical model of the DER system are presented. Then, the second-order sliding mode differentiator is designed to solve the problem of calculation expansion in the backstepping control method. To solve the influence of lumped disturbance on the system, a disturbance-observer is proposed to observe the unknown disturbance and compensate the controller feed-forward. Moreover, fuzzy control is proposed to reduce the dependence of the control effect on model accuracy. Finally, the stability of the controller is verified by Lyapunov stability theory, and the hardware in the loop results is given to verify that the control effect of the proposed DAFC controller has better dynamic performance compared with proportion-integral (PI) and the backstepping control strategy.
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Mao, Jingfeng, Chunyun Yin, Xiaotong Zhang, Aihua Wu i Xudong Zhang. "Learning Observer-Based Sensor Fault-Tolerant Control of Distributed Generation in an Islanded Microgrid for Bus Voltage Stability Enhancement". Sensors 22, nr 18 (13.09.2022): 6907. http://dx.doi.org/10.3390/s22186907.
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In order to improve robust operating performance and enhance bus voltage stability, a learning observer-based fault-tolerant control strategy is proposed for the distributed generation in islanded microgrid with sensor faults and uncertain disturbances. Firstly, the output feedback control theory and the linear matrix inequality method are used to design closed-loop controller for the voltage source inverter of distributed generation; secondly, a fault-tolerant model and control structure of the distributed generation in an islanded microgrid with sensor faults is analyzed. By employing the fault output signal conversion filter and proportional derivative type learning observer, the online estimation and real-time compensation of the sensor fault signal are realized. Thirdly, the system synthesis of output feedback control and fault-tolerant control is completed. Finally, the multi-scenario sensor fault scheme simulation experiment verifies that the proposed control strategy has strong sensor fault tolerance and adaptability.
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Xia, Yan, Yuchen Dai, Wenxu Yan, Dezhi Xu i Chengshun Yang. "Adaptive-Observer-Based Data Driven Voltage Control in Islanded-Mode of Distributed Energy Resource Systems". Energies 11, nr 12 (26.11.2018): 3299. http://dx.doi.org/10.3390/en11123299.
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In this paper, an adaptive observer based data driven control scheme is proposed for the voltage control of dispatchable distributed energy resource (DER) systems which work in islanded operation. In the design procedure of the proposed control scheme, we utilize the novel transformation and linearization technique for the islanded DER system dynamics, which is proper for the proposed data driven control algorithm. Moreover, the pseudo partial derivative (PPD) parameter matrix can be estimated online by multiple adaptive observers. Then, the adaptive constrained controller is designed only based on the online identification results derived from the input/output (I/O) data of the controlled DER system. It is theoretically proven that all the signals in the closed-loop control system are uniformly ultimately bounded based on the Lyapunov stability analysis approach. In addition, the results of the simulation comparison are given to verify the voltage control effect of the proposed control scheme.
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Yang, Minsheng, i Pengcheng Liu. "Research on Sliding Mode Control of Dual Active Bridge Converter Based on Linear Extended State Observer in Distributed Electric Propulsion System". Electronics 12, nr 16 (20.08.2023): 3522. http://dx.doi.org/10.3390/electronics12163522.
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This paper focuses on the high-performance bidirectional DC-DC converter required in distributed electric propulsion (DEP) systems, with the dual active bridge (DAB) converter chosen as the subject of study. To achieve the goal of stabilizing the output voltage while improving the converter’s anti-interference ability and dynamic performance, this paper proposes a novel strategy. In particular, it combines the Linear Extended State Observer (LESO) with a sliding mode control (SMC), proposing a sliding mode control strategy based on the Linear Extended State Observer (LESO-SMC). Notably, this control strategy not only retains the fast dynamic performance of Linear Active Disturbance Rejection Control (LADRC) and the robustness of SMC but also addresses the significant chattering issue inherent in traditional SMC. Comparing the traditional PI, LADRC, and SMC strategies, the results show that when the load changes, the voltage fluctuation of the LESO-SMC strategy proposed in this paper is 0.165 V (0.25 V) in the Matlab/Simulink and RT-Lab platforms, and the average adjustment time is 4 ms (3.5 ms). In contrast, the average voltage fluctuations of PI and LADRC strategies were 3.7 V (4.9 V) and 0.55 V (1.35 V), and the average adjustment times were 99.5 ms (201 ms) and 71.5 ms (77.5 ms), respectively. When the input voltage changes, the proposed LESO-SMC strategy adjusts faster and has almost no voltage fluctuations, while the average voltage fluctuations of the PI and LADRC strategies in the simulation are 0.5 V and 0.1 V, and the average adjustment times are 89.5 ms and 35 ms, and the change in the input voltage in the RT-Lab platform has very little effect on the output voltage. Compared with SMC, the LESO-SMC strategy has no chattering problem. In summary, compared to the other three control strategies, the LESO-SMC strategy proposed in this paper exhibits superior performance in terms of voltage fluctuation and adjustment time during load changes and input voltage changes. It shows a robust anti-interference ability and a rapid dynamic response performance.
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Phan, Dinh Hieu, Minh Tuan Dao, Van Truong Nguyen, Huy Anh Bui, Ngoc Duy Le i Thanh Lam Bui. "Design of super-twisting algorithm control and observer for three-phase inverter in standalone operation". International Journal of Power Electronics and Drive Systems (IJPEDS) 13, nr 1 (1.03.2022): 368. http://dx.doi.org/10.11591/ijpeds.v13.i1.pp368-379.
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This paper develops a new control algorithm of a distributed generation system in the standalone operation. Behaviour of three-phase voltage source inverter is investigated and the guidelines for tuning the control parameters are presented. Based on Super-Twisting algorithm, the proposed controller guarantees the load voltage performance under different types of loads. The proposed controller is established for an inner-loop current controller and an outer-loop voltage controller in a dual control scheme. The proposed scheme is very simple, thus tuning control parameters is easy and the computational burden of the controllers is low. In order to validate the load current of the proposed system feasibility, a reduced-order observer is adopted. The simulation results indicate a more reliable and efficient performance compared to the standard sliding control and the adaptive control.
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Ge, Pudong, Xiaobo Dou, Xiangjun Quan, Qinran Hu, Wanxing Sheng, Zaijun Wu i Wei Gu. "Extended-State-Observer-Based Distributed Robust Secondary Voltage and Frequency Control for an Autonomous Microgrid". IEEE Transactions on Sustainable Energy 11, nr 1 (styczeń 2020): 195–205. http://dx.doi.org/10.1109/tste.2018.2888562.
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Narzary, Daijiry, i Kalyana C. Veluvolu. "Higher Order Sliding Mode Observer-Based Sensor Fault Detection in DC Microgrid’s Buck Converter". Energies 14, nr 6 (12.03.2021): 1586. http://dx.doi.org/10.3390/en14061586.
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Fault detection in a Direct Current (DC) microgrid with multiple interconnections of distributed generation units (DGUs) is an interesting topic of research. The occurrence of any sensor fault in the DC microgrid should be detected immediately by the fault detection network to achieve an overall stable performance of the system. This work focuses on sensor fault diagnosis of voltage and current sensors in interconnected DGUs of the microgrid. Two separate higher order sliding mode observers (HOSM) based on model dynamics are designed to estimate the voltage and current and generate the residuals for detecting the faulty sensors in DGUs. Multiplicative single and multiple sensor faults are considered in voltage and current sensors. By appropriate selection of threshold, single and multiple sensor fault detection strategies are formulated. A hierarchical controller is designed to ensure equal sharing of current among the DGUs of the DC microgrid and stabilize the system. Simulations are performed to validate the proposed approach for various configurations of the DC microgrid under various load and off noise conditions.
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Zhang, Liang, Kang Chen, Ling Lyu i Guowei Cai. "Research on the Operation Control Strategy of a Low-Voltage Direct Current Microgrid Based on a Disturbance Observer and Neural Network Adaptive Control Algorithm". Energies 12, nr 6 (25.03.2019): 1162. http://dx.doi.org/10.3390/en12061162.
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Low-voltage direct current (DC) microgrid based on distributed generation (DG), the problems of load mutation affecting the DC bus under island mode, and the security problems that may arise when the DC microgrid is switched from island mode to grid-connected mode are considered. Firstly, a DC bus control algorithm based on disturbance observer (DOB) was proposed to suppress the impact of system load mutation on DC bus in island mode. Then, in a grid-connected mode, a pre-synchronization control algorithm based on a neural network adaptive control was proposed, and the droop controller was improved to ensure better control accuracy. Through this pre-synchronization control, the microgrid inverters output voltage could quickly track the power grid’s voltage and achieve an accurate grid-connected operation. The effectiveness of the algorithms was verified by simulation.
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Ghasemi, Mohamad Amin, Seyed Fariborz Zarei, Zahra Sohrabi, Frede Blaabjerg i Saeed Peyghami. "An Observer-Based Current Sensor-Less Control Scheme for Grid-Following Converters". Applied Sciences 12, nr 15 (1.08.2022): 7749. http://dx.doi.org/10.3390/app12157749.
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Distributed energy resources based on grid-following inverters are the dominant part of future modern power systems. To achieve a higher performance, the reliability enhancements and cost reductions of such inverters are the most important demands. In this respect, the sensors are one of the elements which greatly determine the cost and reliability of the inverters, and minimizing the number of sensors may achieve both lower costs and higher reliability. In addition, sensor data are prone to cyber-attacks, and sensor-less control techniques would improve the cyber-physical tolerance capabilities of the system. This paper proposes a grid-side current sensor-less control technique for grid-following inverters. In the proposed scheme, an observer is suggested which estimates the grid-side currents by processing the measured DC-link voltage. The estimated grid-side currents are fed to the control loops of the inverter. To verify the effectiveness of the proposed scheme, the stability of the overall control structure is analyzed, including the nonlinear dynamics of the DC-link voltage in the various operating points, using eigen value analysis and time domain simulations. The results demonstrate that the proposed scheme preserves the proper stability margin and performance of the GF-VSC, even in the presence of uncertainty in output filter inductance.
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Wu, Boning, Xuesong Zhou i Youjie Ma. "Bus Voltage Control of DC Distribution Network Based on Sliding Mode Active Disturbance Rejection Control Strategy". Energies 13, nr 6 (14.03.2020): 1358. http://dx.doi.org/10.3390/en13061358.
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The DC distribution network has more advantages in power transmission, grid connection of distributed energy, and reliability of power supply when compared with AC distribution network, but there are still many problems in the development of DC distribution network. DC bus voltage control is one of the hot issues in the research of DC distribution network. To solve this problem, in this paper, a new type of sliding mode active disturbance rejection control (SMADRC) controller for AC/DC converters is designed and applied to the voltage outer loop. The linear extended state observer (LESO) can observe the state variables and the total disturbance of the system. The SMADRC is composed of a sliding mode controller, LESO, and disturbance compensator, which can compensate the total disturbance observed by LESO properly. Therefore, it improves the dynamic. At the same time, it can also reduce the system jitter that is caused by sliding mode controller. The state variables that are observed by the LESO are used in the design of sliding mode controller, which greatly simplifies the design of sliding mode controller. Finally, the simulation results of Matlab/Simulink show that the controller has good start-up performance and strong robustness.
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Aillane, Ali, Karim Dahech, Larbi Chrifi-Alaoui, Aissa Chouder, Tarak Damak, Abdelhak Hadjkaddour i Pascal Bussy. "The Design and Processor-In-The-Loop Implementation of a Super-Twisting Control Algorithm Based on a Luenberger Observer for a Seamless Transition between Grid-Connected and Stand-Alone Modes in Microgrids". Energies 16, nr 9 (3.05.2023): 3878. http://dx.doi.org/10.3390/en16093878.
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The abrupt transfer from grid-connected (GC) to stand-alone (SA) operation modes is one of the major issues that may threaten the stability of a distributed generation (DG) system. Furthermore, if the islanding mode happens, it is vital to take into consideration the load voltages or load current waveforms as soon as feasible. This paper develops an advanced control technique based on a super-twisting sliding mode controller (ST-SMC) for a three-phase inverter operating in both the GC and SA modes. This control scheme is proposed to ensure a smooth transition from the GC to SA mode and enhance the load voltage waveforms under the islanding mode. In addition, to minimize the operational costs of the system and the complexity of the studied model, a digital Luenberger observer (DLO) with a proper design is adopted for estimating the inverter-side current. The control scheme of the whole system switches between a current control mode during the GC mode and a voltage control mode during the SA mode. The super-twisting control algorithm is applied to the outer voltage control loop involved in the cascaded voltage/current control scheme in the SA mode. Simulation tests of a three-phase inverter are performed for the purpose of assessing the suggested control performance by using the PowerSim (PSIM) software and comparing it with a classical PI controller. Furthermore, a processor-in-the-loop (PIL) implementation in a DSP board TMS32F28335 while debugging is conducted using code composer studio 6.2.0. The obtained results show efficient control properties, such as a smooth transition among the microgrid (MG) operating modes, as well as effectiveness and robustness during both the GC and SA operation modes.
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Chen, Mengying, Fengling Han, Long Shi, Yong Feng, Chen Xue, Weijie Gao i Jinzheng Xu. "Sliding Mode Observer for State-of-Charge Estimation Using Hysteresis-Based Li-Ion Battery Model". Energies 15, nr 7 (5.04.2022): 2658. http://dx.doi.org/10.3390/en15072658.
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Lithium-ion battery devices are essential for energy storage and supply in distributed energy generation systems. Robust battery management systems (BMSs) must guarantee that batteries work within a safe range and avoid the damage caused by overcharge and overdischarge. The state-of-charge (SoC) of Li-ion batteries is difficult to observe after batteries are manufactured. The hysteresis phenomenon influences the existing battery modeling and SoC estimation accuracy. This research applies a terminal sliding mode observer (TSMO) algorithm based on a hysteresis resistor-capacitor (RC) equivalent circuit model to enable accurate SoC estimation. The proposed method is evaluated using two dynamic battery tests: the dynamic street test (DST) and the federal urban driving schedule (FUDS) test. The simulation results show that the proposed method achieved high estimation accuracy and fast response speed. Additionally, real-time battery information, including battery output voltage and SoC, was acquired and displayed by an automatic monitoring system. The designed system is valuable for all battery application cases.
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Huang, Min, Han Li, Weimin Wu i Frede Blaabjerg. "Observer-Based Sliding Mode Control to Improve Stability of Three-Phase LCL-Filtered Grid-Connected VSIs". Energies 12, nr 8 (12.04.2019): 1421. http://dx.doi.org/10.3390/en12081421.
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Grid-connected voltage source inverters (VSIs) with LCL filters have been widely used for distributed generation systems (DGs). Various control methods have been studied to achieve good performance. Among them, sliding mode control has been applied to LCL-filtered grid-connected VSIs for its fast, dynamic response and strong robustness. However, LCL networks can easily cause instability problems under weak grid conditions such as grid impedance variation. At the same time, the stability design of sliding mode control applied for LCL-filtered grid-connected inverters are important, but they lack detailed parameters design in recent papers. In this paper, a design of observer-based sliding mode control to improve the stability of three-phase LCL-filtered grid-connected VSIs was proposed. The theoretical stability analysis was developed to consider the effect of the system discretization and grid impedance variations. Finally, a 3-kW, 110-V, 50-Hz experimental setup has been built to demonstrate the validation of the proposed method.
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Dong, Xiaogang, Jinqiang Gan, Hao Wu, Changchang Deng, Sisheng Liu i Chaolong Song. "Self-Triggered Model Predictive Control of AC Microgrids with Physical and Communication State Constraints". Energies 15, nr 3 (5.02.2022): 1170. http://dx.doi.org/10.3390/en15031170.
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In this paper, we investigate the secondary control problems of AC microgrids with physical states (i.e., voltage, frequency and power, etc.) constrained in the process of actual control, namely, under the condition of state constraint. On the basis of the primary control (i.e., droop control), the control signals generated by distributed secondary control algorithm are used to solve the problems of voltage and frequency recovery and power allocation for each distributed generators (DGs). Therefore, the model predictive control (MPC) with the mechanism of rolling optimization is adopted in the second control layer to achieve the above control objectives and solve the physical state constraint problem at the same time. Meanwhile, in order to reduce the communication cost, we designed the self-triggered control based on the prediction mechanism of MPC. In addition, the proposed algorithm of self-triggered MPC does not need sampling and detection at any time, thus avoiding the design of observer and reducing the control complexity. In addition, the Zeno behavior is excluded through detailed analysis. Furthermore, the stability of the algorithm is verified by theoretical derivation of Lyapunov. Finally, the effectiveness of the algorithm is proved by simulation.
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Xu, Gang, i Liang Ma. "Resilient Self-Triggered Control for Voltage Restoration and Reactive Power Sharing in Islanded Microgrids under Denial-of-Service Attacks". Applied Sciences 10, nr 11 (29.05.2020): 3780. http://dx.doi.org/10.3390/app10113780.
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This paper addresses the problem of voltage restoration and reactive power sharing of inverter-based distributed generations (DGs) in an islanded microgrid subject to denial-of-service (DoS) attacks. Note that DoS attacks may block information exchange among DGs by jamming the communication network in the secondary control level of a microgrid. A two-layer distributed secondary control framework is presented, in which a state observer employing the multiagent system (MAS)-based ternary self-triggered control is implemented for discovering the average information of voltage and reactive power in a fully distributed manner while highly reducing communication burden than that the periodic communication way. The compensation for the reference signal to the primary control is acquired according to the average estimates to achieve voltage restoration while properly sharing reactive power among DGs. An improved ternary self-triggered control strategy integrating an acknowledgment (ACK)-based monitoring mechanism is established, where DoS attacks are modeled by repeated cycles of jamming and sleeping. A new triggering condition is developed to guarantee the successful information exchange between DGs when the sleep period of DoS attacks is detected. Using the Lyapunov approach, it is proved that the proposed algorithm allows agents to reach consensus regardless of the frequency of the DoS attacks, which maintains the accurate estimation of average information and the implementation of the secondary control objectives. The performance of the proposed control scheme is evaluated under simulation and experimental conditions. The results show that the proposed secondary control scheme can highly reduce the inter-agent communication as well as improve the robustness of the system to resist DoS attacks.
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S, Adarsh, i Nagendrappa H. "Duty ratio control ofthree port isolated bidirectional asymmetrical triple active bridge DC-DC converter". International Journal of Power Electronics and Drive Systems (IJPEDS) 12, nr 2 (1.06.2021): 943. http://dx.doi.org/10.11591/ijpeds.v12.i2.pp943-956.
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Multiport converters are used in interfacing of distributed energy sources with grid/load. Isolated converters are needed in applications where converter gain is high and there is a requirement of isolation. Dual transformer asymmetric triple active bridge offers the advantage of reduced circulating current. However, the operating range is low for variation in load and source voltage. In this paper duty ratio modulation technique is proposed to regulate the load voltage and control the power flow in both the directions. As a result of the new gating scheme, the converter switches operate with ZVS, irrespective of variations in load power and source voltage. The converter is designed to ensure high switch utilization. The control technique is validatedthrough simulation of a 1kW three port DC-DC converter. It was observerd that the load voltage was regulated for wide range of variation in load power and source port voltages. The single input dual output mode was also verified.
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Ahmad Ganie, Bilal, i Dr (Mrs ). Lini Mathew. "Adaptive Control Scheme for Grid Tied SPV System with DSTATCOM Capabilities: Review". Journal of University of Shanghai for Science and Technology 23, nr 07 (14.07.2021): 678–89. http://dx.doi.org/10.51201/jusst/21/07195.
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This study provides an adaptive control approach of VSC (voltage source converter) coupled with SPV (solar photovoltaic array), in a 3P3W (three-phase three-wire) system with three single-phase non-linear loads having Distributed Static Compensator (DSTATCOM) abilities using P and O (perturb & observe) methodology. The adaptive control technique converges quickly and has a low mean square error. For the correction of power factor and zero voltage regulation modes, the system is studied and simulated. The system’s great efficacy at high voltages is due to its one-stage structure. Grid current harmonics are significantly below the IEEE-519 norm. The suggested system is modeled and simulated with the available sim power system toolbox in MATLAB/Simulink, and the system’s behavior under different loads and environmental circumstances is confirmed.
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Salman, M., S. Hongsheng, M. A. Aman i Y. Khan. "Enhancing Voltage Profile and Power Loss Reduction Considering Distributed Generation (DG) Resources". Engineering, Technology & Applied Science Research 12, nr 4 (1.08.2022): 8864–71. http://dx.doi.org/10.48084/etasr.5046.
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In recent years, Distributed Generation (DG) has received attention due to its benefits to the distribution network. In this paper, the influence of DG along with several techniques for mitigating the detrimental impact on voltage profile and power losses was examined. The test system of 132 KV residential test feeder was selected, examined, and modeled in the Electrical Transient Analyzer Program (ETAP). Various tests were carried out to determine the influence of DG on the distribution network. Results were compared with, and without DG, taking into account the voltage profile. When injecting DG with unity power factor at different buses in a radial test system, it was discovered that when the DG of the right size and type is injected at the ideal position, the voltage profile improves while the power losses are reduced. When an un-deterministic DG is injected at multiple points on the test feeder, no improvement in voltage profile was observed. When the cross-sectional area of conductors is increased and a DG is injected at optimal locations, a positive impact on voltage profile is observed while the detrimental impact on power losses was also analyzed. The findings of this study may be useful to distribution firms regarding the future expansion of the power systems and the proliferation of DG.
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Bulatov, Yuri, Andrey Kryukov i Nguyen Van Huan. "Flicker control in mains with distributed generation plants". E3S Web of Conferences 209 (2020): 07001. http://dx.doi.org/10.1051/e3sconf/202020907001.
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The use of distributed generation (DG) plants in power supply systems is a rapid development line. However, the impact of DG on power quality is multivalued. On the one hand, the presence of DG allows to reduce voltage losses. On the other hand, a phenomenon called flicker and associated with rapid voltage fluctuations is possible. This effect is usually manifested at an abrupt voltage drop in the DG generator connection unit. The processes taking place in the network when flicker occurs in networks with DG have not been sufficiently studied. The article presents results of the flicker modeling in a network equipped with DG plants, implemented on the basis of synchronous generators. The results obtained indicated that with sharp disturbances caused by switching on and off an additional load, flicker is observed in networks with unregulated generators, accompanied by voltage and frequency fluctuations. Based on the wavelet transformation and spectral analysis methods, it was found that the power spectral density of the generated flicker-noise is inversely proportional to the frequency. The use of look-ahead control algorithms to control the excitation and rotors rotational speed of the DG plants generators, as well as concordant adjustment of their controllers, increases stability and removes flicker completely.
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Stringer, Naomi, Navid Haghdadi, Anna Bruce, Jenny Riesz i Iain MacGill. "Observed behavior of distributed photovoltaic systems during major voltage disturbances and implications for power system security". Applied Energy 260 (luty 2020): 114283. http://dx.doi.org/10.1016/j.apenergy.2019.114283.
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Khan, Muhammad Zahid, Chaoxu Mu, Salman Habib, Waleed Alhosaini i Emad M. Ahmed. "An Enhanced Distributed Voltage Regulation Scheme for Radial Feeder in Islanded Microgrid". Energies 14, nr 19 (24.09.2021): 6092. http://dx.doi.org/10.3390/en14196092.
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Even the simplest version of the distribution networks face challenges such as maintaining load voltage and system frequency stability and at the same time minimizing the circulating reactive power in grid-forming nodes. As the consumers at the far end of the radial distribution network face serious voltage fluctuations and deviations once the load varies. Therefore, this paper presents an enhanced distributed control strategy to restore the load voltage magnitude and to realize power-sharing proportionally in islanded microgrids. This proposed study considers the voltage regulation at the load node as opposed to the inverter terminal. At the same time, a supervisory control layer is put on to observe and correct the load voltage and system frequency deviations. This presented method is aimed at replacing paralleled inverter control methods hitherto used. Stability analysis using system-wide methodical small-signal models, the MATLAB/Simulink, and experimental results obtained with conventional and proposed control schemes verify the effectiveness of the proposed methodology.
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Valluri, Ashok Babu. "Novel Control Approach with FRT capability for Grid connected HYBRID distributed generation system using ANN controller based DVR". International Journal for Research in Applied Science and Engineering Technology 9, nr 12 (31.12.2021): 2002–21. http://dx.doi.org/10.22214/ijraset.2021.39684.
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Abstract: For ever increasing power demand and depletion of conventional energy resources, Renewable Energy Systems (RES) became an alternative source of electricity to reduce the load stress on the Power Grid. Although several control & design modifications are presented in past literature to improve reliability & performance of through Distribution Generation (DG) technologies, they always fall short in some aspects of voltage stability and Fault Ride Through (FRT) capabilities. The main aim of the project is Protecting Critical load from Grid side altercations which occur due to harmonics generated by DG’s and Short circuit faults near to load center. This project proposes the application of a Dynamic Voltage Restorer (DVR) to enhance the power quality and improve the Fault Ride Through (FRT) capability of a three-phase medium-voltage network connected to a hybrid distribution generation (DG) system. In this hybrid farm, the Photo Voltaic (PV) plant via single-stage energy conversion (DC-AC inverter) & DFIG (Doubly-Fed Induction Generator) based Wind power plant are connected to the same Point of Common Coupling (PCC). For MPPT of wind power plant, we use Pitch Angle Control (PAC) technique. This topology allows Perturb and observe (P&O) based MPPT algorithm for PV plant through connection of the DG (Distribution generation) system to the public grid through a step-up transformer. In addition, the DVR based on Artificial Neural Network (ANN) controller is connected to the same PCC. Different fault condition scenarios are tested for improving the efficiency and the quality of the power supply and compliance with the requirements of the sensitive Load. The efficiency of this control technique is that it enhances restoration and harmonics suppression capabilities of DVR which are far superior than that of PI controller used in existing model. Keywords: RES, DG, LVRT, FRT, PV, DFIG, PCC, MPPT, P&O, DVR, PI, ANN, THD, Voltage stability.
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Sadeghi, Baran, Nima Shafaghatian, Reza Alayi, Mamdouh El Haj Assad, Farhad Zishan i Hasan Hosseinzadeh. "Optimization of synchronized frequency and voltage control for a distributed generation system using the Black Widow Optimization algorithm". Clean Energy 6, nr 1 (27.12.2021): 869–82. http://dx.doi.org/10.1093/ce/zkab062.
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Abstract A distributed generation network could be a hybrid power system that includes wind–diesel power generation based on induction generators (IGs) and synchronous generators (SGs). The main advantage of these systems is the possibility of using renewable energy in their structures. The most important challenge is to design the voltage-control loop with the frequency-control loop to obtain optimal responses for voltage and frequency deviations. In this work, the voltage-control loop is designed by an automatic voltage regulator. A linear model of the hybrid system has also been developed with coordinated voltage and frequency control. Dynamic frequency response and voltage deviations are compared for different load disturbances and different reactive loads. The gains of the SG and the static volt-ampere reactive compensator (SVC) controllers in the IG terminal are calculated using the Black Widow Optimization (BWO) algorithm to insure low frequency and voltage deviations. The BWO optimization algorithm is one of the newest and most powerful optimization methods to have been introduced so far. The results showed that the BWO algorithm has a good speed in solving the proposed objective function. A 22% improvement in time adjustment was observed in the use of an optimal SVC. Also, an 18% improvement was observed in the transitory values.
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Li, Zhongwen, Zhen Fan i Guofu Zhou. "Nanoscale Ring-Shaped Conduction Channels with Memristive Behavior in BiFeO3 Nanodots". Nanomaterials 8, nr 12 (11.12.2018): 1031. http://dx.doi.org/10.3390/nano8121031.
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Nanoscale ring-shaped conduction channels with memristive behavior have been observed in the BiFeO3 (BFO) nanodots prepared by the ion beam etching. At the hillside of each individual nanodot, a ring-shaped conduction channel is formed. Furthermore, the conduction channels exhibit memristive behavior, i.e., their resistances can be continuously tuned by the applied voltages. More specifically, a positive (negative) applied voltage reduces (increases) the resistance, and the resistance continuously varies as the repetition number of voltage scan increases. It is proposed that the surface defects distributed at the hillsides of nanodots may lower the Schottky barriers at the Pt tip/BFO interfaces, thus leading to the formation of ring-shaped conduction channels. The surface defects are formed due to the etching and they may be temporarily stabilized by the topological domain structures of BFO nanodots. In addition, the electron trapping/detrapping at the surface defects may be responsible for the memristive behavior, which is supported by the surface potential measurements. These nanoscale ring-shaped conduction channels with memristive behavior may have potential applications in high-density, low-power memory devices.
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Bulatov, Yu N. "Joint voltage and frequency predictive controllers for distributed generation plants". iPolytech Journal 25, nr 5 (9.11.2021): 568–85. http://dx.doi.org/10.21285/1814-3520-2021-5-568-585.
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The paper determines the effect of proposed joint voltage and frequency predictive controllers for distributed generation (DG) plants on quality indicators characterizing the control process in different operating modes of power supply systems. The studies are conducted in the MatLab environment (Simulink and SimPowerSystems simulation packages) employing control engineering methods. It is proposed to design and adjust joint predictive controllers by determining the resonant frequency of oscillations for the master generator rotor. This approach provides better quality indicators of voltage and frequency control in power supply systems while maintaining the same settings for the controllers of DG plants. With an additional load in an isolated power supply system, the maximum voltage sag is found to be 1.75 times lower than for local predictive control and 3.5 times lower as compared to the use of conventional controllers. For the specified mode, predictive controllers enable a threefold reduction in the transient time between rotor rotational speeds in a synchronous generator. In the start mode of a powerful electric motor, the predictive controllers of synchronous generators in the power supply system enable a 1.5 times reduction in voltage sag, with a 1.4 times reduction in overvoltage following its start. In the case of a short-term three phase short-circuit, joint predictive controllers allow a 1.5 times decrease in transient time and a 2.3 times decrease in the overshoot of power line frequency as compared to local control. In addition, frequency oscillation in the power system is also reduced. Similar effects are observed in other operating modes of the considered power supply systems equipped with DG plants. The performed dynamic simulation confirms the effectiveness of using joint voltage and frequency predictive controllers for DG plants, which consists in a positive impact on the quality of processes involved in controlling the parameters of power supply systems in various operating modes.
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Torres, Negreiros i Tiba. "Theoretical and Experimental Study to Determine Voltage Violation, Reverse Electric Current and Losses in Prosumers Connected to Low-Voltage Power Grid". Energies 12, nr 23 (29.11.2019): 4568. http://dx.doi.org/10.3390/en12234568.
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The impact of PV generation distributed in a low voltage transmission line depends on many factors: The distribution lines and PV generators characteristics, its location, operational control, local meteorological conditions, electricity consumption profile, and the electricity cost variation. An atypical and challenging behavior of photovoltaic distributed generation (DG) insertion in consumer units (CUs), implies in some circumstances, as the reverse directionality of the power flow between the load equipped with a photovoltaic system generator and the electrical grid, when a CU contains a distributed generation and low power consumption, the power flow will be directed to the power electric grid. In this work, the modeling of a low-voltage real feeder was performed, setting the variables of the system under real operating conditions. As result, voltage levels variability throughout the feeder, the electrical losses, and the asymmetry between the phases were observed. Through simulation scenarios, the occurrence of voltage increase under different penetration scenarios of distributed generation was verified and there was a 10% increase in reference voltage as well as the occurrence of higher electrical losses by reverse current, reaching 1200% more with a DG penetration, in the massive presence of the photovoltaic generator. The mitigatory action used in this work was able to attenuate the negative impacts to the feeder circuit, ensuring the integrity grid and the consumer unit.
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Pijarski, Paweł, i Piotr Kacejko. "Voltage Optimization in MV Network with Distributed Generation Using Power Consumption Control in Electrolysis Installations". Energies 14, nr 4 (14.02.2021): 993. http://dx.doi.org/10.3390/en14040993.
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Connecting a large number of distributed sources to the medium and low voltage grid poses many problems. The most important of these are the voltage changes inside the network, what can be observed when the power flow from these sources towards the HV/MV (High Voltage/Medium Voltage) transformer station. In particular, if the power consumption in nodes of the MV network is small and the distance between the place of installation of the source and the substation is large, increases and changes in voltage may be dangerous for the insulation of the network and burdensome for the consumers connected to it. The solution most frequently used to control voltage increases is the appropriate setting of the controller that affects the on-load tap changer of the MV/HV or even MV/LV (Medium Voltage/Low Voltage) transformer. It is also possible to regulate the reactive power of the sources and, of course, to limit their generated active power (curtailment of generation). The development of energy storage technology has made it possible to introduce consumers into the network, whose power can be controlled in a wide range. The article proposes the concept of an innovative voltage control system in the MV network, whose output values are three groups of parameters: HV/MV transformer ratio, reactive power of sources and active power of consumers connected in generation nodes. In the technological sense, it has been assumed that the loads are installations of electrolyzers used to produce “green hydrogen”, according to the P2G (Power to Gas) formula. The tests consisting in the execution of several hundred calculation cycles for the IEEE 37 test network, using the Monte Carlo simulation, have shown that the subordination of the hydrogen production process to the objectives of voltage control in the MV network clearly contributes to stabilizing its value, while meeting the technological requirements. The control variables of the proposed control system are the result of the optimization algorithm described in the article, the function of which is the quality of network voltage.
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Nagai, Hiroki, Tatsuya Suzuki, Yoshihisa Takahashi i Mitsunobu Sato. "Photovoltaic lithium-ion battery fabricated by molecular precursor method". Functional Materials Letters 09, nr 03 (czerwiec 2016): 1650046. http://dx.doi.org/10.1142/s1793604716500466.
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A novel thin-film lithium-ion battery (LIB) which can be charged by the light irradiation was fabricated by molecular precursor method. The unprecedented, translucent thin-film LIB, fabricated on a fluorine-doped tin oxide pre-coated glass substrate, was attained by using the active materials, titania for anode and LiCoO2 for cathode, respectively. The averaged potential at 2.04[Formula: see text]V was observed by applying a constant current of 0.2[Formula: see text]mA. Then, that at 1.82[Formula: see text]V was detected after 60[Formula: see text]s during the sequential self-discharge process. The charging voltage of the assembled battery was 1.38[Formula: see text]V with irradiation of 1-sun, the self-discharge voltage was 1.37[Formula: see text]V. Based on the calibration curve of the charging voltages over constant currents ranging from 0–1.0[Formula: see text]mA, the detected value can be theoretically reduced to the charging operation by applying a constant current of approximately 60[Formula: see text][Formula: see text]A. The charge and discharge of this device was stable voltage at least 30 cycles. The two-in-one device can simultaneously generate and store electricity from solar light, the renewable energy source, and may be applied in smart windows for distributed power system according to on-site demand.
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Lukács, G. L., i E. Moczydlowski. "A chloride channel from lobster walking leg nerves. Characterization of single-channel properties in planar bilayers." Journal of General Physiology 96, nr 4 (1.10.1990): 707–33. http://dx.doi.org/10.1085/jgp.96.4.707.
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A novel, small conductance of Cl- channel was characterized by incorporation into planar bilayers from a plasma membrane preparation of lobster walking leg nerves. Under conditions of symmetrical 100 mM NaCl, 10 mM Tris-HCl, pH 7.4, single Cl- channels exhibit rectifying current-voltage (I-V) behavior with a conductance of 19.2 +/- 0.8 pS at positive voltages and 15.1 +/- 1.6 pS in the voltage range of -40 to 0 mV. The channel exhibits a negligible permeability for Na+ compared with Cl- and displays the following sequence of anion permeability relative to Cl- as measured under near bi-ionic conditions: I- (2.7) greater than NO3- (1.8) greater than Br- (1.5) greater than Cl- (1.0) greater than CH3CO2- (0.18) greater than HCO3- (0.10) greater than gluconate (0.06) greater than F- (0.05). The unitary conductance saturates with increasing Cl- concentration in a Michaelis-Menten fashion with a Km of 100 mM and gamma max = 33 pS at positive voltage. The I-V curve is similar in 10 mM Tris or 10 mM HEPES buffer, but substitution of 100 mM NaCl with 100 mM tetraethylammonium chloride on the cis side results in increased rectification with a 40% reduction in current at negative voltages. The gating of the channel is weakly voltage dependent with an open-state probability of 0.23 at -75 mV and 0.64 at +75 mV. Channel gating is sensitive to cis pH with an increased opening probability observed for a pH change of 7.4 to 11 and nearly complete inhibition for a pH change of 7.4 to 6.0. The lobster Cl- channel is reversibly blocked by the anion transport inhibitors, SITS (4-acetamido, 4'-isothiocyanostilbene-2,2'-disulfonic acid) and NPPB (5-nitro-2-(3-phenylpropylamino)benzoic acid). Many of these characteristics are similar to those previously described for small conductance Cl- channels in various vertebrate cells, including epithelia. These functional comparisons suggest that this invertebrate Cl- channel is an evolutionary prototype of a widely distributed class of small conductance anion channels.
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Abdul Hamid, Zulkiffli, Ismail Musirin, Ammar Yasier Azman i Muhammad Murtadha Othman. "Continuous domain ant colony optimization for distributed generation placement and losses minimization". IAES International Journal of Artificial Intelligence (IJ-AI) 9, nr 2 (1.06.2020): 261. http://dx.doi.org/10.11591/ijai.v9.i2.pp261-268.
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This paper proposes a method for distributed generation (DG) placement in distribution system for losses minimization and voltage profile improvement. An IEEE 33-bus radial distribution system is used as the test system for the placement of DG. To facilitate the sizing of DG capacity, a meta-heuristic algorithm known as Continuous Domain Ant Colony Optimization (ACO<sub>R</sub>) is implemented. The ACO<sub>R</sub> is a modified version of the traditional ACO which was developed specially for solving continuous domain optimization problem like sizing a set of variables. The objective of this paper is to determine the optimal size and location of DG for power loss minimization and voltage profile mitigation. Three case studies were conducted for the purpose of verification. It was observed that the proposed technique is able to give satisfactory results of real power loss and voltage profile at post-optimization condition. Experiment under various loadings of the test system further justifies the objective of the study.
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Bhatti, Bilal Ahmad, Robert Broadwater i Murat Dilek. "Analyzing Impact of Distributed PV Generation on Integrated Transmission & Distribution System Voltage Stability—A Graph Trace Analysis Based Approach". Energies 13, nr 17 (1.09.2020): 4526. http://dx.doi.org/10.3390/en13174526.
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The use of a Graph Trace Analysis (GTA)-based power flow for analyzing the voltage stability of integrated Transmission and Distribution (T&D) networks is discussed in the context of distributed Photovoltaic (PV) generation. The voltage stability of lines and the load carrying capability of buses is analyzed at various PV penetration levels. It is shown that as the PV generation levels increase, an increase in the steady state voltage stability of the system is observed. Moreover, within certain regions of stability margin changes, changes in voltage stability margins of transmission lines are shown to be linearly related to changes in the loading of the lines. Two case studies are presented, where one case study involves a model with eight voltage levels and 784,000 nodes. In one case study, a voltage-stability heat map is used to demonstrate the identification of weak lines and buses.
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Musa, Abdulhamid, i Tengku Juhana Tengku Hashim. "Optimal sizing and location of multiple distributed generation for power loss minimization using genetic algorithm". Indonesian Journal of Electrical Engineering and Computer Science 16, nr 2 (1.11.2019): 956. http://dx.doi.org/10.11591/ijeecs.v16.i2.pp956-963.
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This paper presents a Genetic Algorithm (GA) for optimal location and sizing of multiple distributed generation (DG) for loss minimization. The study is implemented on a 33-bus radial distribution system to optimally allocate different numbers of DGs through the minimization of total active power losses and voltage deviation at power constraints of 0 – 2 MW and 0 – 3 MW respectively. The study proposed a PQ model of DG and Direct Load Flow (DLF) technique that uses Bus Incidence to Branch current (BIBC) and Branch Current to Bus Voltage (BCBV) matrices. The result obtained a minimum base case voltage level of 0.9898 p.u at bus 18 with variations of voltage improvements at other buses after single and multiple DG allocations in the system. Besides, the total power loss before DG allocation is observed as 0.2243 MW, and total power loss after DG allocation was determined based on the power constraints. Various optimal locations were seen depending on the power limits of different DG sizes. The results have shown that the impact of optimal allocation and sizing of three DG is more advantageous concerning voltage improvement, reduction of the voltage deviation and also total power loss in the distribution system. The results obtained in the 0 – 2 MW power limit is consistent to the 0 – 3 MW power limits regarding the influence of allocating DG to the network and minimization of total power losses.
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Bawa, Abubakar, Muhammad Uthman, Farouq E. Shaibu i Koledowo Saliu Oyewale. "Optimal Sizing and Sitting of Distributed Generation for Power Quality Improvement of Distribution Network". European Journal of Engineering Research and Science 4, nr 10 (15.10.2019): 18–23. http://dx.doi.org/10.24018/ejers.2019.4.10.1555.
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The Point of Common Coupling (PCC) where suppliers’ responsibility and customers demand meet is of great concern due to increase degree of voltage variation assessment; valuable indicator of system conditions (voltage profile). Unstable condition of the power system outside operational or statutory limit, an adverse effect of nonlinear loads usually generate harmonics as well as fundamental frequency voltage variations and increase rate of power losses. These loads need to be compensated for. The major concerns of utility operations is to mitigate adverse effect of this system conditions. This research work focuses on optimal siting and sizing of Distributed Generation (DG) in a 43 bus distribution system. Power losses coupled with voltage deviation, considering objective function that compute present percentage losses in 11kV Dikko feeder, Abuja Electricity Distribution Company (AEDC), Suleja Distribution Network, Nigeria. We identified buses with poor voltage profile without DG installation and determined optimal sizing and siting of DGs where losses can be mitigated and power quality improved. ETAP version 12.6 2014 was used for load flow analysis to establish a decisive based case. The total load of the system considered was (3490 + j2700) kVA. Active and Reactive power losses in the system before DG installation were 246.300 kW and 289.903 kVAR respectively. DGs installation in the case study, has a considerable effects on loss reduction in the network. It is observed that 8.10% and 7.20% active and reactive power loss reduction was achieved while bus voltage improved by 0.4%. Genetic Algorithm Optimization techniques programmed in MATLAB 2015 software was used for optimal placement and sizing of the DG in the system.
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Bawa, Abubakar, Muhammad Uthman, Farouq E. Shaibu i Koledowo Saliu Oyewale. "Optimal Sizing and Sitting of Distributed Generation for Power Quality Improvement of Distribution Network". European Journal of Engineering and Technology Research 4, nr 10 (15.10.2019): 18–23. http://dx.doi.org/10.24018/ejeng.2019.4.10.1555.
Pełny tekst źródłaStreszczenie:
The Point of Common Coupling (PCC) where suppliers’ responsibility and customers demand meet is of great concern due to increase degree of voltage variation assessment; valuable indicator of system conditions (voltage profile). Unstable condition of the power system outside operational or statutory limit, an adverse effect of nonlinear loads usually generate harmonics as well as fundamental frequency voltage variations and increase rate of power losses. These loads need to be compensated for. The major concerns of utility operations is to mitigate adverse effect of this system conditions. This research work focuses on optimal siting and sizing of Distributed Generation (DG) in a 43 bus distribution system. Power losses coupled with voltage deviation, considering objective function that compute present percentage losses in 11kV Dikko feeder, Abuja Electricity Distribution Company (AEDC), Suleja Distribution Network, Nigeria. We identified buses with poor voltage profile without DG installation and determined optimal sizing and siting of DGs where losses can be mitigated and power quality improved. ETAP version 12.6 2014 was used for load flow analysis to establish a decisive based case. The total load of the system considered was (3490 + j2700) kVA. Active and Reactive power losses in the system before DG installation were 246.300 kW and 289.903 kVAR respectively. DGs installation in the case study, has a considerable effects on loss reduction in the network. It is observed that 8.10% and 7.20% active and reactive power loss reduction was achieved while bus voltage improved by 0.4%. Genetic Algorithm Optimization techniques programmed in MATLAB 2015 software was used for optimal placement and sizing of the DG in the system.
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P., Dr Karrupusamy. "Synchronization of Reactive Power in Solar Based DG and Voltage Regulated Elements Using Stochastic Optimization Technique". Journal of Electrical Engineering and Automation 2, nr 1 (30.03.2020): 50–59. http://dx.doi.org/10.36548/jeea.2020.1.006.
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As the distribution generation (DG) based on the solar has attained more prominence and are broadly utilized by multitudes of client and the manufacturers of power on distribution system that is radial. The solar based distributed generation for the radial distribution system affects the changeover functions of the tap changers that are less laden as well as the capacitors connected in shunt and further causes loss of power. The paper attempts in developing an innovative process of synchronization using the stochastic optimization technique the particle swarm optimization to bring together the reactive power of the distribute generation of the solar and the elements that are regulated using the voltage. The synchronization is performed by predicting the load. The procedure for the performing the synchronization is framed on the operational cost and the cost of power loss as multi-objective function. The methodology followed in the paper is examined in the MATLAB over 10 kV, sixteen buses. The observed results were compared with the traditional methodologies to determine the efficacy eluding any failures in the conditions of the GRID.
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Ahmed, Ahmed Jassim, Mohammed H. Alkhafaji i Ali Jafer Mahdi. "Performance enhancement of a low-voltage microgrid by measuring the optimal size and location of distributed generation". ACTA IMEKO 11, nr 3 (11.09.2022): 1. http://dx.doi.org/10.21014/acta_imeko.v11i3.1270.
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<p class="Abstract">A power system in which the generation units such as renewable energy sources and other types of generation equipment are located near loads, thereby, reducing operation costs and losses and improving voltage is called a distributed generation (DG), and these generation units are called distributed energy resources. However, DGs must be located optimally to improve the power quality and minimize power loss of the system. The objective of this paper is to propose an approach for measuring the optimal size and location of DGs in a low voltage Microgrid using the Autoadd algorithm. The algorithm is validated by testing it on the IEEE 33-bus standard system and compared with previous studies, the algorithm proved its efficiency and superiority on the other techniques. A significant improvement in voltage and reduction in losses were observed when the DGs are placed at the sites decided by the algorithm. Therefore, Autoadd can be used in finding the optimal sizes and locations of DGs in the distribution system, the possibility of isolating the low voltage Microgrid is discussed by integrating distributed generation units and the results showed the possibility of this scenario during faults time and intermittency of energy time.</p>
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Yee, Myat Mon, i Chatchai Sirisamphanwong. "Analysis of the Impact of Distributed Grid-Connected PV System on Power Quality of the Electrical Distribution Network". Applied Mechanics and Materials 839 (czerwiec 2016): 124–29. http://dx.doi.org/10.4028/www.scientific.net/amm.839.124.
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Electricity generation from solar energy by using PV cells is drastically increased due to global warming concern, greenhouse effect, and quality of living standards. However, PV generation may offer variable and unpredictable energy output due to intermittent nature of solar irradiance and hence, integration of PV into grid may provide some drawback effect to the power system. The aim of this paper is to investigate the impact of grid connected PV system on the power quality of distribution network. The power quality analysis is based on real measurements of 10 kWp, Energy Park SERT, School of Renewable Energy, Naresuan University, Thailand. Parameters such as active and reactive power, voltage, current, power factor, THDv, THDi, individual harmonic voltage and harmonic current are observed for the investigation of the interaction between SERT PV system and distribution network’s power quality. According to the measured data, PV system operation is negligible in terms of voltage distortion, voltage magnitude and frequency variation. Therefore, it can be noticed that 10 kWp SERT PV system does not effect on the distribution system power quality due to low PV penetration level.
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Lindner, T., G. Paasch i S. Scheinert. "Influence of distributed trap states on the characteristics of top and bottom contact organic field-effect transistors". Journal of Materials Research 19, nr 7 (lipiec 2004): 2014–27. http://dx.doi.org/10.1557/jmr.2004.0265.
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Numerical simulations of organic field-effect transistors (OFET) of bottom and top contact (BOC, TOC) design with different source/drain contacts were carried out considering an exponential distribution of trap states in the gap of the active layer (a-Si model). For ohmic contacts, the current-voltage characteristics are similar to the trap-free case and there is not much difference between the two designs. However, the currents are lower due to immobile trapped charges, the threshold voltage is shifted, and the inverse subthreshold slope increases due to trap recharging. An analytical approximation for the effective mobility deviates from the simulation up to 20%. For low source/drain work function, there occur particular dependencies of the current on the gate voltage for the two designs, which are explained with the internal concentration and field profiles. A series resistance between source and channel causes in the TOC structure an abrupt transition from the gate voltage independent active region into saturation. In the BOC case, the reverse-biased Schottky-type source contact dominates the current. Through simulation of measured characteristics of prepared OFETs based on a modified poly-(phenylene-vinylene), the observed hysteresis is analyzed.
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Liu, Qijian, Hu Sun, Tao Wang i Xinlin Qing. "On-Site Health Monitoring of Composite Bolted Joint Using Built-In Distributed Eddy Current Sensor Network". Materials 12, nr 17 (29.08.2019): 2785. http://dx.doi.org/10.3390/ma12172785.
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There is an urgent need to monitor the structural state of composite bolted joints while still remaining in service; however, there are many difficulties in analyzing their strength and failure modes. In this paper, a built-in distributed eddy current (EC) sensor network based on EC array sensing film is developed to monitor the hole-edge damages of composite bolted joints. The EC array sensing film is bonded onto the bolt and consists of one exciting coil and four separate sensing coils. Experiments are conducted on unidirectional composite specimens to validate the ability of the EC array sensing film to quantitatively track the damage that occurs at the hole edge and to investigate the performances of the EC array sensing films with different configurations of the exciting coil. Experimental results show that the induced voltage of sensing coil changes only if the damage appears on the laminate structure where that particular sensing coil is located, whereas the induced voltages of the other sensing coils on other laminate plates remain unchanged. Numerical simulation based on the finite element method is also carried out to investigate and explain the phenomena observed in the experiments and to analyze the distribution of the EC around the bolt hole. Both experimental and numerical simulation results demonstrate that the developed EC array sensing film can effectively identify not only whether there is damage at the hole edge but also the damage location within the thickness and quantitative size.
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Kauer, John S., Angel Cinelli, David Wellis i Joel White. "Observation of neuronal activity using real-time voltage-sensitive dye imaging". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 1 (sierpień 1992): 476–77. http://dx.doi.org/10.1017/s0424820100122782.
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Sensory systems are confronted with the problem of taking “information” in the outside world and encoding and manipulating it in forms that can be used in the neuronal world. A major challenge is to document how the transition between these worlds takes place (transduction) and, once it has taken place, how the data are manipulated by neural circuits (integration). Since the brain is an intrinsically parallel device, carrying out many functions simultaneously, it would appear as important to record brain activity in a similarly parallel manner as to record events in single cells and membranes. Optical recording of neuronal events offers a first step toward thing to observe events that are distributed among the cells and processes of a neuronal network.In the sense of smell odors appear to be encoded by activity distributed across many neurons at each level of the system studied so far, from the sensory cells in the nose to the pyramidal cells in prepyriform cortex (for review see). Thus, to elucidate how the molecular properties of odorants are represented by neurons it is probably necessary to observe the patterns of distributed activation. The distribution of activity across many neuronal elements, in contrast to representing odor molecules by dedicated “labelled lines”, confers redundancy and fault tolerance on a system that is crucial for complex behaviors that underly survival for many animals species, as well as providing flexibility for being sensitive to large numbers of compounds.
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Moya, Alexander Paul, Polo Josue Pazmiño, Jacqueline Rosario Llanos, Diego Ortiz-Villalba i Claudio Burgos. "Distributed Secondary Control for Battery Management in a DC Microgrid". Energies 15, nr 22 (21.11.2022): 8769. http://dx.doi.org/10.3390/en15228769.
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This research presents the design and simulation of a distributed secondary control based on a consensus algorithm for the efficient management of an isolated DC microgrid (MG-DC) that secures the distribution of active power according to the capacities of each storage unit, reducing duty cycles and extending its life cycle. The balance of powers is fulfilled through a photovoltaic (PV) generation unit and an energy storage system (ESS) based on batteries. The PV Boost converter has a maximum power point tracking (MPPT) controller based on the perturb and observe (P & O) method. In contrast, a Buck–Boost converter is integrated into each battery, which is bidirectionally controlled through a local controller and a primary droop control that balances the required power at the loads. It produces a voltage deviation on the DC bus. To compensate for this deviation, a distributed secondary control strategy based on consensus is proposed to restore the voltage while managing the power sharing according to the capacities of each battery. It allows for the improvement of its life cycle, which is shown in the state of charge (SOC) index, thus extending its life cycle. The controllers are evaluated for solar re-source changes, load changes, and different storage capacities.
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Barzegari, Yousof, Jafar Zarei, Roozbeh Razavi-Far, Mehrdad Saif i Vasile Palade. "Resilient Consensus Control Design for DC Microgrids against False Data Injection Attacks Using a Distributed Bank of Sliding Mode Observers". Sensors 22, nr 7 (30.03.2022): 2644. http://dx.doi.org/10.3390/s22072644.
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This paper investigates the problem of false data injection attack (FDIA) detection in microgrids. The grid under study is a DC microgrid with distributed boost converters, where the false data are injected into the voltage data so as to investigate the effect of attacks. The proposed algorithm uses a bank of sliding mode observers that estimates the states of the neighbor agents. Each agent estimates the neighboring states and, according to the estimation and communication data, the detection mechanism reveals the presence of FDIA. The proposed control scheme provides resiliency to the system by replacing the conventional consensus rule with attack-resilient ones. In order to evaluate the efficiency of the proposed method, a real-time simulation with eight agents has been performed. Moreover, a verification experimental test with three boost converters has been utilized to confirm the simulation results. It is shown that the proposed algorithm is able to detect FDI attacks and it protects the consensus deviation against FDI attacks.
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Meng, Xiao Fang, Ying Nan Wang, Li Di Wang i Jue Wang. "Distributed Generation Optimal Planning Approach Based on the Planning Platform of the Distribution Network". Advanced Materials Research 614-615 (grudzień 2012): 1381–84. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.1381.
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For optimal planning distributed generation (DG) in the distribution network well, this paper proposed the approach to optimal configuration DG on the distribution planning platform(DPP). This paper analyzed the zone selection for placement DGs, and built the selective zone’s network on the DPP. The site and size of DG was determined according to the node priority, the annual minimum electric power loss and maximum economic benefit. Moreover, the power flow was calculated after and before placing DGs, and the results were showed on the DPP, which included power flow, node voltage, and the siting and sizing of DG. By the planning DG results under different load instance, it is more intuitive to analyze the node voltage, branch flow and loss, and to observe the site and size of DG on the DPP. The method provides the necessary support of data and technology to optimal planning DG.
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Park, Chanyang, Jun-Sik Yoon, Kihoon Nam, Hyundong Jang, Minsang Park i Rock-Hyun Baek. "Investigation of Program Efficiency Overshoot in 3D Vertical Channel NAND Flash with Randomly Distributed Traps". Nanomaterials 13, nr 9 (24.04.2023): 1451. http://dx.doi.org/10.3390/nano13091451.
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The incremental step pulse programming slope (ISPP) with random variation was investigated by measuring numerous three−dimensional (3D) NAND flash memory cells with a vertical nanowire channel. We stored multiple bits in a cell with the ISPP scheme and read each cell pulse by pulse. The excessive tunneling from the channel to the storage layer determines the program efficiency overshoot. Then, a broadening of the threshold voltage distribution was observed due to the abnormal program cells. To analyze the randomly varying abnormal program behavior itself, we distinguished between the read variation and over−programming in measurements. Using a 3D Monte−Carlo simulation, which is a probabilistic approach to solve randomness, we clarified the physical origins of over−programming that strongly influence the abnormal program cells in program step voltage, and randomly distributed the trap site in the nitride of a nanoscale 3D NAND string. These causes have concurrent effects, but we divided and analyzed them quantitatively. Our results reveal the origins of the variation and the overshoot in the ISPP, widening the threshold voltage distribution with traps randomly located at the nanoscale. The findings can enhance understanding of random over−programming and help mitigate the most problematic programming obstacles for multiple−bit techniques.
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Ashigwuike, Evans Chinemezu, i Stephen Adole Benson. "Optimal Location and Sizing of Distributed Generation in Distribution Network Using Adaptive Neuro-Fuzzy Logic Technique". European Journal of Engineering Research and Science 4, nr 4 (20.04.2019): 83–89. http://dx.doi.org/10.24018/ejers.2019.4.4.1237.
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The growing gap between electric power generated and that demanded is of utmost concern especially in developing economy, hence calling for measures to argument the existing power generated of which DG is a more viable aspect to explore in curtailing this challenges; although been confronted with issue of location and sizing. This research applied Adaptive neuro fuzzy logic technique to optimize DG location and size. A 24 bus radial network was used to demonstrate this process and having a suitable location and size at optimal position reduces power losses and also improves the voltage profile at the buses. The method was simulated using ANFIS toolbox MATLAB R2013b (8.2.0.701) 64-bit software and tested using Gwagwalada injection sub-station feeder 1 system. The results obtained were compared to that obtained using ANN. It was observed that adaptive neuro fuzzy logic technique performed better in terms of reducing power losses compared to ANN technique. The percentage reduction in the power loss at the buses cumulatively is 48.96% for ANN while adaptive neuro fuzzy logic technique is 49.21%. The voltage profile of the networks after optimizing the DG location and sizes using adaptive neuro fuzzy logic technique were also found to be much improved with the lowest bus voltage improved from 0.9284 to 1.05pu.
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Ashigwuike, Evans Chinemezu, i Stephen Adole Benson. "Optimal Location and Sizing of Distributed Generation in Distribution Network Using Adaptive Neuro-Fuzzy Logic Technique". European Journal of Engineering and Technology Research 4, nr 4 (20.04.2019): 83–89. http://dx.doi.org/10.24018/ejeng.2019.4.4.1237.
Pełny tekst źródłaStreszczenie:
The growing gap between electric power generated and that demanded is of utmost concern especially in developing economy, hence calling for measures to argument the existing power generated of which DG is a more viable aspect to explore in curtailing this challenges; although been confronted with issue of location and sizing. This research applied Adaptive neuro fuzzy logic technique to optimize DG location and size. A 24 bus radial network was used to demonstrate this process and having a suitable location and size at optimal position reduces power losses and also improves the voltage profile at the buses. The method was simulated using ANFIS toolbox MATLAB R2013b (8.2.0.701) 64-bit software and tested using Gwagwalada injection sub-station feeder 1 system. The results obtained were compared to that obtained using ANN. It was observed that adaptive neuro fuzzy logic technique performed better in terms of reducing power losses compared to ANN technique. The percentage reduction in the power loss at the buses cumulatively is 48.96% for ANN while adaptive neuro fuzzy logic technique is 49.21%. The voltage profile of the networks after optimizing the DG location and sizes using adaptive neuro fuzzy logic technique were also found to be much improved with the lowest bus voltage improved from 0.9284 to 1.05pu.
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Krismanto, Awan Uji, Hafizhul Ayyasi Khairullah, Irrine Budi Sulistiawati, Abraham Lomi i Dipu Sarkar. "Probabilistic Static Voltage Stability of Power System with Integration of PV Generators using Monte Carlo Simulations". Proceedings of the Pakistan Academy of Sciences: A. Physical and Computational Sciences 58, S (11.10.2021): 73–84. http://dx.doi.org/10.53560/ppasa(58-sp1)735.
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As a renewable source, the uncertainties and intermittencies of solar irradiance have become the main concern in developing and integrating such power generation into an electricity network. In power system operation, it is important to maintain a stable voltage profile under random power injection from renewable power generations. The effect of photovoltaic (PV) power plants on the static voltage stability of the interconnected power system is presented in this paper. The probabilistic study was conducted through Monte Carlo Simulation (MCS) to investigate the fluctuation of voltage profiles under uncertain power injection from PV power plants. The standard test system of IEEE 14 bus and practical test system of Lombok, West Nusa Tenggara electricity network are investigated. It was noticed that the installation of a photovoltaic power plant affected the voltage profiles. The fluctuated condition of power injection from PV power plant resulted in more fluctuation of voltage profiles as indicated by higher standard deviation values. Moreover, distributed location of the PV power plant also influenced the circumstances of voltage fluctuation, providing less fluctuated condition of voltage profiles. Eventually, it can be observed that the voltage fluctuation would influence the static voltage stability of the interconnected power system.