调相机接入后距离保护Ⅱ段的定值优化策略

A Setting Optimization Strategy for Distance ProtectionⅡafter Connection of Synchronous Condensers

调相机大规模接入电网后会使线路距离保护Ⅱ段的保护范围缩小,保护定值的合理优化是解决该问题的可行途径。为此,分析了调相机接入对距离保护Ⅱ段的影响,提出了一种扩大距离保护Ⅱ段保护范围的定值优化策略。首先,分析调相机的稳态电流以及短路电流,从保护范围的角度分析在传统距离保护Ⅱ段整定方法下调相机接入对距离保护Ⅱ段的影响。然后,从合理选取保护范围设定值与准确计算分支系数出发,提出了距离保护Ⅱ段的定值优化策略,有效扩大了调相机接入后距离保护Ⅱ段的保护范围。最后,对所提定值优化策略进行仿真分析,结果表明,新方法所得的保护范围受调相机接入台数以及相邻线路阻抗比的影响较小,且保护范围可以接近于设定值。

The large-scale access of synchronous condensers(SCs)to the power grid will reduce the protection range of the distance protection sectionⅡ,and reasonable optimization of the protection setting is a feasible way to solve this problem.For this reason,based on an investigation of the influence of the SCs connection on the distance protection sectionⅡ,a setting value optimization strategy is proposed to increase the protection range of the distance protection sectionⅡ.Firstly,the steady-state current and shortcircuit current of SCs are analyzed,and the influence of the SCs access on the protection range under the traditional distance protectionⅡsetting is investigated from the perspective of the protection range.And then,for the purpose of reasonable selection of the protection range setting value and accurate calculation of branch coefficients,a setting value optimization strategy of distance protection sectionⅡis proposed,which effectively improves the protection range of the distance protection sectionⅡafter SCs access.Finally,a simulation analysis is conducted on the setting value optimization strategy proposed in this paper,and the results show that the protection range obtained by the proposed method is less affected by the number of SCs and the impedance ratio of adjacent lines,and can be close to the preset value.