新能源送出线路工频变化量距离保护不正确动作机理分析  

Analysis of the incorrect operation mechanism of power frequency variation-based distance protection in new energy transmission lines

作　　者：戴志辉[1] 韦舒清 柳梅元 DAI Zhihui;WEI Shuqing;LIU Meiyuan(Hebei Laboratory of Distributed Energy Storage and Microgrid(North China Electric Power University),Baoding 071003,China)

机构地区：[1]河北省分布式储能与微网实验室(华北电力大学),河北保定071003

出　　处：《电力系统保护与控制》2025年第6期74-86,共13页Power System Protection and Control

基　　金：国家自然科学基金项目资助(51877084)。

摘　　要：大规模新能源经交流联络线送出已成为新型电力系统的典型场景。在此背景下,受新能源系统运行方式的影响,工频变化量距离保护存在不正确动作风险。为进一步探究工频变化量距离保护性能下降机制,基于电压平面分析可知,在光伏场站控制策略的作用下,光伏场站馈出正序电流表征为相位、幅值皆受控的非线性变量,造成保护补偿电压大小随故障工况变化且矢量方向发生不确定性偏转,导致保护动作可行域不明确,从而造成基于传统整定判据下的阻抗继电器性能严重劣化。在此基础上,借助距离保护正确动作边界条件与光伏场站接入容量的对应关系,提出了保护适用性快速评估与保护失效边界接入容量计算方法。基于PSCAD/EMTDC建立了光伏场站送出系统仿真模型,通过大量仿真验证了理论分析的正确性。Large-scale integration of new energy through AC interconnection lines has become a typical scenario in modern power systems.In the present situation,because of the influence of the operation mode of new energy systems,power frequency variation-based distance protection faces the risk of incorrect operation.To further investigate the performance degradation mechanism of this protection method,voltage plane analysis reveals that under the control strategy of photovoltaic(PV)power stations,the positive-sequence current at the PV station output exhibits phase-and magnitude-controlled nonlinear characteristics.This causes the protection compensation voltage to vary with fault conditions,with its vector direction undergoing uncertain deviations,leading to an unclear operating region for protection operation.Consequently,the performance of impedance relays based on traditional setting criteria is severely degraded.On this basis,leveraging the relationship between the boundary conditions for correct operation in distance protection and the PV station’s integration capacity,a method for rapid assessment of protection applicability and calculation of the integration capacity value at the boundary of protection failure is proposed.A PSCAD/EMTDC simulation model of the distribution network is established,and the correctness of the theoretical analysis are validated through extensive simulations.

关 键 词：距离保护 工频变化量 相间阻抗继电器 不正确动作 

分 类 号：TM7[电气工程—电力系统及自动化]