基于测量导纳变化的微电网群联络线保护方案

当多个相邻微电网之间通过低压配电线路互联互供时,则形成微电网群。微电网群内部联络线故障时,方向不定的网络潮流,易变的拓扑结构以及多样的逆变式分布式电源控制策略等因素,给微电网群的保护带来了挑战。文中根据微电网群系统故障前后线路电压和电流的分布特点,提出一种以母线测量导纳量变化量为判据的微电网群内部联络线保护新方案。该方案采用故障前后联络线两端测量导纳的幅值变化为初步判据,选出疑似故障线路,并结合疑似线路两侧导纳相角差的变化实现故障线路识别。该方法原理简单,易于整定,具有较高的灵敏度和可靠性。利用PSCAD/EMTDC进行算例验证,结果证实了该方案的正确性和可靠性。

Protection scheme for tie lines of multi-microgrid based on measured bus admittance

With increasing interconnection and interaction among the adjacent microgrids, multi-microgrid is formed. Multi-microgrid has many new characteristics, such as bi-directional power flows, flexible operation modes and different control strategy of inverter interfaced distributed generations (IIDGs), which challenge multi-microgrid protection. Based on the voltage and current distribution characteristics of the line parameters, this paper proposes a new protection scheme for internal tie lines fault of multi-microgrid, which takes the change of measured bus admittance as the criterion. First, measured admittance amplitude of both ends of tie lines, before and after the fault are calculated. Then, comparing the admittance amplitude to select the likely faulty lines. Finally, fault line is located on comparison the phase of measured admittance among the likely faulty lines. This scheme with high sensitivity and reliability, has a simple principle and is easy to be adjusted. PSCAD/EMTDC is used in simulation analysis, and simulation results have verified the correctness and effectiveness of the protection scheme.