用于同杆双回线保护的时域电容电流的分相补偿方法

Study of Time-domain Compensation Algorithm of Capacitive Current for Parallel Transmission Lines Protection

分相电流差动保护常作为同杆双回线的主保护配置,但对于超高压及特高压远距离输电线路,分布电容电流将大到影响保护的可靠性和灵敏度。现有的电容电流补偿方法,都只补偿了单回线相间电容电流,没有考虑双回线线间电容电流的补偿,补偿效果有限。考虑了同杆双回线相间与线间的静电耦合,建立了相应∏模型等效电路,提出在时域中分相补偿电容电流的方法,不仅可以补偿相间电容电流,还可很好地补偿线间电容电流。EMTP仿真实验表明,新补偿法比原单回线的相量及时域补偿法具有更好的补偿效果,有效提高了同杆双回线上分相电流差动保护的灵敏度和可靠性,且新方法计算量小、不要求高采样率,无需引入另回线电流,适用于现有采样率不高、通道传输速率有限的继保装置中。

As for long parallel UHV/EHV transmission lines, the sensitivity and reliability of the differential protection is affected a lot by the distributed capacitive current. By establishing the П mode circuit for the parallel transmission lines, a novel time-domain capacitive current compensation method is proposed. This method without requirement for the information of the other line works better than the traditional compensation methods, since it can compensate both the interphase capacitive current and the capacitive current between parallel transmission lines. Theory analysis and EMTP simulation show that, the reliability and sensitivity of the differential protection on parallel transmission lines is effectively enhanced by using the compensation method. In addition, since the proposed algorithm is required for neither high sampling rate nor heavy computation, it can operate well on the existing relay devices with limited sampling rate and telecommunication traffic.