基于暂态电流波形特征的快速差动保护新原理

A Transient Current Waveform Feature Based Novel High-speed Differential Protection

随着大规模交直流互联系统的发展,系统故障后引发的问题越发严重,因此对继电保护的性能提出了更高的要求。线路故障暂态量中蕴含有丰富的故障信息,通过对故障分量暂态差动电流的研究发现:区内故障时故障相呈工频变化规律;区内故障时非故障相及区外故障时的各相均呈高频变化规律,且存在理论最小振荡频率。据此提出一种基于暂态电流波形的纵联保护新原理,采用最小二乘拟合提取暂态波形主频率并构造了相应保护判据。经仿真验证,该方法能够可靠、灵敏地识别区内、外各类短路故障,有效提高了保护动作速度,具有较强耐过渡电阻和抗高频噪声干扰的能力,对采样频率要求不高,具有一定的实用价值。

With the development of large-scale AC/DC hybrid systems,the problems caused by system faults become more and more serious.So higher requirements are placed on the performance of the relay protection.The line fault transients contain a wealth of fault information.Through the research on the transient differential current of the fault component,it is found that the fault phase appears as a power frequency under internal fault.The non-fault phase of internal fault and each phase of the external fault appear as a high-frequency,and there is a theoretical minimum frequency.Therefore,a new pilot protection principle based on transient current waveform was proposed.The least squares fitting method is used to extract the frequency information and the corresponding protection criterion was constructed.Through simulation verification,the proposed protection can reliably and sensitively identify various internal and external faults,effectively improve the protection action speed,and has strong resistance to transition resistance and high frequency noise interference.The proposed protection has low requirements on sampling frequency,which has certain practical value.