Voltage sag assessment of large power grid based on branch change influence domain

Abstract

The change of a large-scale power grid topology leads to the change of node voltage sag assessment results. Thus, it is necessary to re-simulate massive line fault scenarios. However, the simulation time of the existing assessment methods is too long to ensure the practicability of the project. 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, the branch change influence index is constructed to quantify the influence law of the branch change on the node voltage sag level. Secondly, based on the different influence degrees of each region, an adaptive electrical distance threshold selection method is proposed and then the range of the branch change influence domain is divided in order to construct and simulate the fault scene in the branch change influence domain. Finally, the historical simulation results are updated by using the simulation results of the branch change influence domain fault, and the severity of the node voltage sag after the topology change is calculated. Through the example of the IEEE118 node system and the actual grid structure of a city in Fujian, it has been proved that the proposed method can effectively reduce the fault simulation time by up to 96% and improve the efficiency of the voltage sag assessment of a large-scale power grid.