电力电子设备接入电压支撑强度量化评估指标综述

当前，大规模新能源发电、柔性直流输电等电力电子设备接入系统存在规模受限、暂态过电压、控制失稳等问题，其严重程度与系统的电压支撑强度密切相关。该文以电力电子设备并网系统为背景，对电压支撑强度的量化评估指标——短路比指标、阻抗比指标的构建与应用进行综述。分析电力系统强弱的关键特性及其与量化评估指标之间的关联，阐述了电压支撑强度的概念。一方面，短路比作为量化评估系统电压支撑强度的重要指标，根据电力电子设备并网后的系统特征，发展不同形式的构建方法。采用短路比指标衡量电压支撑强度时，临界短路比是划分系统强弱的重要判据，与系统静态电压稳定密切相关，当前临界短路比应用于新能源系统时存在计算方法及数值不统一的问题。另一方面，通过推导阻抗比与临界短路比之间的数学关系，分析阻抗比对电压支撑强度的影响，确定短路比与阻抗比在电压支撑强度量化评估应用中的配合关系。该文对现有的电压支撑强度量化评估指标存在的问题进行分析与总结，建议在评估电压支撑强度时将短路比指标作为主要指标，将阻抗比指标作为辅助指标，为衡量系统对电力电子设备接纳能力的后续研究提供参考。

Overview of Strength Quantification Indexes of Power System With Power Electronic Equipment

The scale limit,transient overvoltage,control instability and other issues may occur when the large-scale power electronic equipment such as renewable energy system and VSC-HVDC is connected to a weak power system.The severity of these problems is related to the system strength.In this paper,based on the scenarios of power system with power electronic equipment,the construction methods and applications of quantification indexes were summarized.The concept of system strength was expounded by analyzing the key characteristics of power system and the relationship with quantification indexes.The short circuit ratio(SCR)index is an important quantification index and its construction methods can be diversified according to the characteristics of the system with power electronic equipment.The critical short circuit ratio(CSCR)is the criterion to divide the system strength and its calculation methods.The numerical inconsistency were analyzed.Next,the influence of impedance ratio(IR)on the system strength was analyzed by deducing the influence of IR on CSCR.This paper summarized the problems of existing quantification indexes,and suggested that the SCR index should be taken as the main index and the IR index as the auxiliary index in the system strength evaluation,so as to provide a reference for follow-up researches on measuring the system acceptance capacity of power electronic equipment.