基于有限PMU的广域后备保护研究

Study of wide area backup protection based on limited number of PMU

对新型的基于有限数量相量测量单元(PMU)的广域后备保护进行了研究。通过布点算法,在电网相关母线中安装有限的相量测量单元,根据布点算法形成的电压推算关系构成保护区,将故障视为'透明',利用安装点的实测值推算保护区内其余的母线电压。故障时,根据正序电压幅值分布特征定位故障关联母线,推算该母线关联支路的有功功率,根据相对误差特征选出故障线路。PMU的高速实测数据的引入使得实时故障定位成为可能。算例仿真验证了基于有限PMU的广域后备保护的正确性和有效性。

A principle of wide area backup protection based on limited number of PMU is analyzed. Through a placement algorithm, a limited number of PMUs are placed on a few buses in the power grid. Then, the power grid is divided into several protection zones according to the estimation structure formed by the placement algorithm. When a short-circuit fault occurs in the transmission line, the bus with the lowest positive sequence voltage will be identified. Then, the branches connected to the identified bus are selected and active power flow is estimated. The short-circuit fault is invisible during the estimation process. Then the faulted line is identifi＇ed according to the relative error. The high speed data of PMU makes real-time fault location possible. The schemes and algorithms mentioned above are proved to be correct and effective by lots of simulations.