特高压直流故障对交流系统稳定性的影响分析

摘要

Based on the different operation modes of Xinjiang UHV AC/DC hybrid sending grid in 2016, the influence of different failures occurring in ±800 kV UHVDC transmission system on the voltage of AC system near the Kumul Prefecture is analyzed through simulation.Different control strategies are adopted according to different failure forms, and the influence of different control strategies on the operating voltage of AC/DC hybrid transmission system is analyzed.The research results are as follow: when DC system failure occurs, in view of different types of failures, DC monopole blocking results in low power surplus and a less influence on system operating stability;Bipolar blocking results in high power surplus which leads to the decrease of AC bus voltage along the line, even the voltage instability and a big influence on AC/DC hybrid transmission system.Commutation failure has a large effect on system transient voltage stability.With the constantly increase of DC power delivered to the outside, no matter DC bipolar blocking failure or the commutation failure, they all will lead to more serious transient voltage rise.%基于2016年新疆特高压交直流混联送端电网不同的运行方式,仿真分析±800 kV特高压直流输电系统发生不同类型的故障时对哈密地区与近区交流系统电压的影响;并且针对不同的故障形式采取不同的控制策略,分析不同控制策略对于交直流混联系统运行电压的影响.研究结果表明,在直流系统发生故障时,从故障类型来看,直流单极闭锁故障时,富裕功率小,对系统稳定运行影响小;双极闭锁故障时,富裕功率大,从而引起沿线交流母线电压的降低,严重时则引起电压失稳,对系统稳定运行影响大;发生换相失败对系统暂态电压稳定性影响较大.随着直流外送功率的不断增大,无论是直流双极闭锁故障还是换相失败故障均会出现暂态压升更加严重的局面.