A Study on Anti-Islanding Detection Algorithms for Grid-Tied Photovoltaic Systems

This work presents a Matlab/Simulink study on anti-islanding detection algorithms for a 100kW Grid-Connected Photovoltaic (PV) Array. The main focus is on the islanding phenomenon that occurs at the Point of Common Coupling (PCC) between Grid-Connected PV System and the rest of the electric power system (EPS) during various grid fault conditions. The Grid-Connected PV System is simulated under the conditions of islanding, and anti-islanding (AI) relay reaction times are measured through the simulation. Results are presented for Grid-Connected PV System equipped with various AI prevention schemes such as over-current and under-current (OI/UI), over-voltage and under-voltage (OV/UV), over-frequency and under-frequency (OF/UF), rate of change of frequency (ROCOF) and Vector Shift. These scenarios are used to evaluate and determine the performance of the AI detection methods and select the most appropriate AI detection algorithm and its corresponding settings for Grid-Connected PV Systems. The AI protections was tested in case of complete disconnection of the PV system from the electric power grid and also in case of various grid faults. However, the detailed simulation results are presented only for the first study case. The theoretical simulation results are useful to design the AI protection devices for Grid-Connected PV Systems and select the points where islanding conditions may occur and the AI relays should to be inserted. From the results provided by the performed Matlab and Simulink simulations, it was observed that using traditional relays for islanding detection such as the OI or UV resulted in significantly better performance in respect to detection time of islanding conditions. The ROCOF and Vector Shift relays have a detection time comparable with frequency relays. However, if the ROCOF threshold is exceeded, the formation of an island is quickly detected. The effects of unintentional islanding were observed from simulation of transient grid faults on a power distribution network. The protection equipment needs to distinguish between islanding event and grid faults. The Grid-Connected PV System Anti-Islanding Protections should detect the fault and trip before islanding occurs as a result of the opening of the circuit breaker in response to a downstream fault.Please cite my paper in your work: I. V. Banu, M. Istrate, D. Machidon and R. Pantelimon, "A study on anti-islanding detection algorithms for grid-tied photovoltaic systems," 2014 International Conference on Optimization of Electrical and Electronic Equipment (OPTIM), Bran, 2014, pp. 655-660. doi: 10.1109/OPTIM.2014.6850940 URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6850940&isnumber=6850869

本研究以 Matlab/Simulink 为工具，对 100kW 并网光伏阵列的防孤岛检测算法进行了深入研究。研究焦点集中在并网光伏系统与电力系统（EPS）其他部分在电网故障条件下，在公共连接点（PCC）出现的孤岛现象。在孤岛条件下对并网光伏系统进行仿真，并通过仿真测量了防孤岛（AI）继电器的反应时间。研究展示了配备多种防孤岛策略的并网光伏系统，包括过电流与欠电流（OI/UI）、过电压与欠电压（OV/UV）、过频率与欠频率（OF/UF）、频率变化率（ROCOF）以及矢量偏移。这些场景被用于评估和确定防孤岛检测方法的性能，并选择适用于并网光伏系统的最合适的防孤岛检测算法及其相应设置。在光伏系统与电网完全断开以及电网出现各种故障的情况下，对 AI 保护进行了测试。然而，详细的仿真结果仅展示了第一个研究案例。理论仿真结果对于设计并网光伏系统的 AI 保护装置以及选择可能发生孤岛条件的点及应插入 AI 继电器的位置具有重要意义。通过对 Matlab 和 Simulink 仿真所提供的结果进行分析，观察到使用传统的孤岛检测继电器，如过电流或欠电压继电器，在检测孤岛条件的时间方面表现出显著优越的性能。频率继电器的检测时间与 ROCOF 和矢量偏移继电器相当。然而，如果 ROCOF 阈值被超过，孤岛的形成可以迅速被检测到。通过对电力分配网络中瞬态电网故障的仿真，观察到了意外孤岛现象的影响。保护设备需要区分孤岛事件和电网故障。并网光伏系统防孤岛保护应检测故障并在孤岛发生之前断开，这是由于对下游故障响应而打开断路器所致。请引用我的论文：I. V. Banu, M. Istrate, D. Machidon 和 R. Pantelimon, “A study on anti-islanding detection algorithms for grid-tied photovoltaic systems,” 2014 International Conference on Optimization of Electrical and Electronic Equipment (OPTIM), Bran, 2014, pp. 655-660. doi: 10.1109/OPTIM.2014.6850940 URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6850940&isnumber=6850869