基于电流相角变化量的含DG配网保护方案研究

Study on protection scheme of distribution network with DG based on current phase angle variation

随着分布式电源(distributed generation,DG)的大量接入,传统配电网的结构由单端电源供电结构变为多端供电系统,DG出力的随机性和间歇性将导致基于电流幅值的单端量保护难以整定和配合。针对以上不足,分析了故障前后电流幅值和相角的变化,得出故障位置不同时电流相角变化方向的差异,并采用一种基于电流相角变化量的纵联保护方案。该方案仅需比较电流状态信息,对通信通道要求较低,可节省安装电压互感器,具有良好的经济性。最后通过PSCAD软件仿真结果可证明,对于不同类型、不同位置的故障,该保护方案均能准确动作且不受过渡电阻的影响。

With the large-scale access of distributed generation(DG),the structure of traditional distribution network changes from single-terminal power supply structure to multi-terminal power supply system.The randomness and intermittency of DG output will make it difficult to set and cooperate with the single-terminal power protection based on current amplitude.In view of the above deficiencies,this paper analyzes the changes of current amplitude and phase Angle before and after the fault,obtains the relationship between the direction of current phase Angle change and the fault position,and thus adopts a longitudinal protection scheme based on the change of current phase Angle.This scheme only needs to compare the current state information,and has low requirements for the communication channel.It can save the installation of voltage transformer and has good economy.Finally,the simulation results of PSCAD software can prove that the protection scheme can operate accurately for different types and different positions of faults and is not affected by the transition resistance.