基于支路变化影响域的大型电网电压暂降评估

Voltage Sag Evaluation of Large Power Grid Based on Influence Domain of Branch Changes

大型电网拓扑结构变化会导致节点电压暂降评估结果改变,需重新进行海量线路故障场景仿真,但现有评估方法仿真时间过长,难以保证工程实用性。针对上述问题,提出了一种基于支路变化影响域的大型电网电压暂降评估方法。首先,通过构建针对基于支路变化的等值网络,推导出支路变化后待评估节点的暂降幅值变化函数,研究支路变化对节点电压暂降水平的影响规律;其次,基于各区域的不同影响程度提出自适应电气距离阈值选取方法,划分支路变化影响域范围,以此构建支路变化影响域内的故障场景并进行仿真;再次,利用支路变化影响域故障仿真结果,更新全网历史仿真结果,计算支路变化后的节点电压暂降严重程度;最后,通过对IEEE118节点系统以及华东某地市的实际网架结构进行实例分析,证明该文方法至多能够有效减少约91%的故障仿真时间,提升大型电网电压暂降评估效率。

The changes of the large-scale power grid topology may lead to the changes of the node voltage sag assessment results.Thus,it is necessary to re-simulate massive line fault scenarios.However,the simulations of the existing assessment methods usually take much long time so that the practicability of the project may not be ensured.To solve the problems above,we propose a voltage sag assessment method for a large-scale power grid based on the branch change influence domain.Firstly,by constructing an equivalent network based on the branch changes,the variation function of the voltage sag amplitude of the nodes to be evaluated after branch changes is deduced.The influence of the branch changes on the voltage sag level of the nodes is studied.Secondly,based on the different influence degrees of each of the regions,an adaptive electrical distance threshold selection is proposed to divide the range of the branch change influence domain so as to construct the fault scenes in the branch change influence domain and simulate it.Thirdly,the historical simulation results are updated by using the simulation results of the branch change influence domain faults,and the severity of the node voltage sag after the topology change is calculated.Finally,through the example analysis of the IEEE118 nodes system and the actual grid structure of a city in East China,it is proved that the proposed method is able to effectively reduce the fault simulation time by up to 91%and improve the efficiency of voltage sag assessment of a large power grid.