逆变器正斜率特性实现方法及系统稳定性分析

摘要

逆变器处于传统的定熄弧角控制时,其负斜率的伏安特性可能与整流器外特性曲线有多个交点,导致高压直流输电系统处于不确定的运行状态.介绍一种将逆变器定γ控制负斜率变为正斜率的方法,通过引入直流电流与其整定值的偏差量来修正定γ控制的斜率,建立了系统等值电路,并引入劳斯-胡尔维茨判据不计算特征值来判别系统的稳定性.分析结果表明逆变器定γ控制正斜率特性可以消除多个运行点的不确定性,增强控制系统的稳定性.%There will be multi-points of intersection between negative slope volt-ampere characteristic of high voltage direct current (HVDC) inverter and exterior characteristic curve of rectifier,when HVDC inverter is in the control of traditional constant arc extinguishing angle γ,which leads to HVDC system operate on the uncertain running state.This paper introduces a method of transforming negative slope characteristic into positive slope characteristic of constant γ control in HVDC inverter.The slope of constant γcontrol is corrected by the dispersion between direct current and its setting value of HVDC inverter.The systematic equivalent circuit of HVDC is established and systematic stability is analyzed by Routh and Hurwitz's criterion without solving the eigenvalues.Results show that positive slope characteristic of constant γ control can eliminate the uncertainty for multi-run points and enhance control systematic stability of HVDC system.