多回特高压直流分层馈入模式下交直流混联系统的稳态特性分析

摘要

For three infeed modes of multi-loop UHVDC:simply into UHVAC,simply into EHVAC and hierarchically into UHVAC and EHVAC,the steady-state characteristics of AC-DC hybrid system are analyzed in three aspects:MISCR(Multi-Infeed Short Circuit Ratio),AC system steady-state voltage and UHVDC transmission power limit.A method of UHVDC transmission power limit analysis based on the self-organized critical slow process is proposed.The effectiveness of the proposed method is verified by simulating the feeding of a dual-loop UHVDC into AC grid and the results show that,the hierarchical infeed mode has better MISCR to enhance the voltage support capability of AC grid for UHVDC.%针对多回特高压直流单层接入特高压交流电网、单层接入超高压交流电网及分层接入特高压和超高压交流电网这3种模式,从多馈入短路比、交流系统稳态电压以及直流极限传输功率3个角度分析交直流混联系统的稳态特性,并提出基于自组织临界慢过程的直流极限传输功率分析方法.通过对两回特高压直流馈入的某区域电网进行仿真计算,验证分析方法的有效性.结果表明在一般情况下,采用分层馈入模式有助于提高系统的多馈入短路比,增强交流系统对特高压直流的电压支撑能力.