有限PMU下采用差动有功功率抗过渡电阻的广域后备保护

The Wide-area Backup Protection Based on Differential Active Power Against Transition Resistance Using Limited PMUs

针对广域后备保护算法易受过渡电阻的影响,研究有限同步相量测量单元（phasor measurement unit,PMU）下基于差动有功功率（differential active power,DAP）的广域后备保护算法。将电网分为若干区域,计算各区域的正序DAP,与阈值比较,判别故障区域。由有限的布置PMU母线电压推算出未布置PMU母线电压幅值,采用线路两侧的推算电压差可识别出故障区域中的故障线路。当发生高阻接地故障不能识别故障线路时,计算各线路的DAP,分析其在线路故障与正常时的差异特性。针对无分支和有分支结构,分别研究故障线路检测判据。对于有分支结构,采用动态加权因子,由各PMU侧电压电流较准确地推算未布PMU母线电压。根据未布置PMU母线各侧的推算电压之间的相位关系,构造线路正序、零序、负序DAP的故障判据。通过IEEE 39节点系统大量仿真实验验证算法的有效性。该算法能够准确检测故障线路,不受故障点位置、故障类型、负荷等影响,且在过渡电阻达到300Ω时仍能准确识别故障线路。

The existing wide-area backup protection algorithms may be influenced by the transition resistance. A novel wide-area backup protection algorithm based on the differential active power（DAP） was proposed. Firstly, the positive sequence differential active power of each subarea was obtained and compared with the threshold to identify the faulted zone. After estimating the voltage amplitude of the phasor measurement unit（PMU） uninstalled bus with those of PMU-installed bus, the faulted line in faulted zone can be detected by the calculated voltage difference on both sides. When the faulted line cannot be detected by the high resistance, the DAP of each line need be calculated. The differences of the DAPs among the faulted and normal lines were analyzed. For the structures with branches and without branches, the fault detecting criteria were respectively given. For the structure with the branches, the dynamic weighting factor method was constructed to accurately estimate the bus voltages where PMUs are not installed, using the voltages and currents from PMUs. According to the phase relationships among estimated voltages in faulted zone, the fault detecting criterions of positive, zero and negative sequence DAPs were given. The simulation experiments on IEEE 39 testing system proved the effectiveness of proposed algorithm. The algorithm can accurately detect faulted line with various fault scenarios, not affected by the fault location, type, and loads, even when thetransition resistance reaches to 300Ω.