注入电流分布特性辨识的配电网故障选线方法

Injection Current Distribution Characteristics Identification Based Distribution-Level Fault Line Selection

针对谐振接地系统单相接地故障特征微弱,基于故障特征的选线方法灵敏度和可靠性降低的问题,提出一种主动注入信号辨识的故障选线方法。首先,推导了注入电流受线路对地导纳影响下的分布特性,利用此分布特性构造选线判据。然后,从不同角度分析了注入信号对系统运行的影响,选择适宜参数的注入信号。考虑降低注入频率能够提高主动注入式选线方法的耐过渡电阻能力,故选择注入低频信号。测量注入信号后各条馈线的零序电流,选择稳态零序电流时间窗,利用Prony算法辨识各条线路零序电流中25 Hz电流幅值完成故障选线。最后,Pscad仿真和现场实测波形验证结果表明,该方法在不同故障场景下均能准确实现故障选线,且具有良好的耐过渡电阻能力。

Addressing the challenges posed by the subtle characteristics of single-phase grounding faults in resonant grounding systems,which lead to decreased sensitivity and reliability in fault line selection methods reliant on these characteristics,an innovative approach for fault line selection through active injection signal identification is proposed.Initially,the distribution characteristics of the injected current,influenced by line-to-ground conductance,are derived.These characteristics then form the foundation for constructing a robust line selection criterion.Furthermore,a thorough analysis is conducted to assess the impact of the injected signal on system operation from various perspectives.This analysis leads to the selection of an optimal injection signal with suitable parameters.Notably,to enhance the method's resilience against transition resistance,a decision is made to inject a low-frequency signal.Subsequently,the zero-sequence current of each feeder line is measured after injecting the signal.A specific steady-state zero-sequence current time window is identified,and the Prony algorithm is employed to accurately discern the 25Hz current amplitude within the zero-sequence current of each line.This approach enables precise fault line selection.Extensive PSCAD simulations and on-site waveform measurements validate the effectiveness of this method.The results demonstrate its ability to accurately identify fault lines across a range of fault scenarios,while maintaining excellent resistance to transition resistance.