复杂多端柔直配电网短路故障全过程全网特征量计算方法
Short-circuit Calculation Method of Whole Network Characteristic Quantity During the Whole Fault Process in Complex Multi-terminal Flexible DC Distribution Network
戴志辉 1李涵伟 1李毅然1
作者信息
- 1. 新能源电力系统国家重点实验室(华北电力大学),保定 071003
- 折叠
摘要
多端柔直配电网短路阻尼小、惯性低,系统中存在大量电力电子器件使得故障发展呈强非线性、阶段性特征,传统短路计算方法关注"点"和"线"的故障特征,难以顾及"网"级特性.为此,着眼短路故障从电容放电到交流侧馈流发展的全过程,系统引入直流故障口理论,首先利用阻抗的高频特性将故障网络合理化简,再经拉普拉斯反变换后得到电容放电阶段的故障电流时域近似解,并通过故障口阻抗求得全网特征量;在交流稳态馈流阶段,建立了换流器端口转移矩阵,经换相重叠修正后消去网络中的混联节点,进而得到适用于多端柔直配电网的稳态短路计算方法.最后,基于PSCAD/EMTDC平台搭建仿真模型,验证了不同故障位置及过渡电阻下所提短路计算方法的准确性.
Abstract
Multi-terminal flexible DC distribution network has small short-circuit damping and low inertia,and the fault development presents the characteristics of strong nonlinearity and stage due to the existance of a large number of power electronic devices in the system.Conventional short-circuit calculation methods concern fault characteristics of"points"and"lines",making it difficult to consider the network-level characteristics.Therefore,this paper focuses on the whole process of short-circuit fault from capacitor discharge to AC-side feed current,and introduces the theory of DC fault ports.On this basis,the fault network is simplified by using high-frequency equivalent characteristics,and then the approximate solution of the fault current in the capacitor discharge stage is obtained by the Laplace inverse transformation.Subse-quently,the characteristic quantity of the whole network is obtained by fault-port impedance.In the steady-state AC feed stage,the converter port transfer matrix is established,the series-connected nodes in the network are eliminated after commutation overlap correction,and then the steady-state short-circuit calculation method suitable for multi-terminal flexible DC power grids is obtained.Finally,a simulation model is built based on PSCAD/EMTDC platform,which veri-fies the accuracy of the proposed short circuit calculation method under different fault locations and fault resistances.
关键词
多端柔直配电网/短路计算/故障口/高频等效/换相重叠Key words
multi-terminal flexible DC distribution network/short circuit calculation/fault port/high-frequency equiva-lence/commutation overlap引用本文复制引用
出版年
2024
国家科技期刊平台
NSTL
万方数据