Equivalent traveling waves based current differential protection of EHV/UHV transmission lines
Equivalent traveling waves based current differential protection of EHV/UHV transmission lines
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DOI：
10.1016/j.ijepes.2017.11.017
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发表时间：
2018-04
影响因子：
5.2
通讯作者：
Aoyu Lei;Xinzhou Dong;Shenxing Shi;Bin Wang;V. Terzija
中科院分区：
文献类型：
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作者：
Aoyu Lei;Xinzhou Dong;Shenxing Shi;Bin Wang;V. Terzija
电流差动保护是特/特高压（EHV/UHV）输电线路最重要的初级保护之一。虽然应用广泛，但存在同步错位、电流互感器饱和、线路容性充电电流等主要不利因素，可能导致误操作。为了解决这些问题，提出了一种基于等效行波（ETW）概念的电流差动保护新方法。该保护方法不受CT饱和和线路电容充电电流的影响，工作速度超高速，不需要同步采样。在保护方法中，利用小波变换模极大值（WTMM）重构当前的etw，从而将通信流量降低到适当的水平。然后利用重建的etw建立了百分比约束操作准则。此外，为了避免外部故障发生在与被保护线路形成平行路径但与被保护线路没有互耦的线路上时可能发生的误操作，还采用了阻塞方法。大量的仿真验证了所提出的保护方法可以作为一种安全可靠的初级保护，用于非、并联或串联补偿的高灵敏度传输线，甚至是内部高阻故障。
Current differential protection is one of the most important primary protections of extra/ultra-high-voltage (EHV/UHV) transmission lines. Despite its wide application, there exist major adverse factors of synchronization misalignment, current transformer (CT) saturation and line capacitive charging current, which may lead to a mal-operation. To solve these problems, a new current differential protection method, based on the concept of equivalent traveling wave (ETW), is proposed. The protection method is immune to CT saturation and line capacitive charging current, operates at an ultra-high speed, and does not require synchronized sampling. In the protection method, wavelet transform modulus maxima (WTMM) are used to reconstruct the current ETWs and thus reduce the communication traffic to an appropriate level. The reconstructed ETWs are then used to establish the percentage restraint operation criterion. Besides, a blocking method is implemented to avoid possible mal-operation when an external fault occurs on a line that forms a parallel path but has no mutual coupling with the protected line. Extensive simulations verify that the proposed protection method can serve as a secure and reliable primary protection for non-, shunt-, or series-compensated transmission lines with high sensitivity, even on internal high-resistance faults.