±800 kV天中特高压直流送端系统安全稳定性分析

Analysis on Security and Stability of ±800 kV Tianzhong UHVDC Sending Grid

为分析天中特高压直流送端电网安全稳定性,基于有效短路比(OESCR)、投切滤波器和直流单(双)极闭锁故障分析不同直流运行工况对送端电网的影响,在此基础上分析疆内电网一次调频作用下直流系统的频率特性、配套机组跳闸与单极闭锁故障下直流孤网运行特性。结果表明,直流配套火电6/8台机可建立工况运行,直流联网运行下其频率特性受疆内电网调频影响较大;直流孤网运行时,在配套机组跳闸或单极闭锁故障后无控制措施情况下,均易引起直流系统频率稳定和暂态过电压问题,此时须考虑稳控切机或直流功率紧急控制提升直流系统安全稳定性。

In order to analyze the security and stability of Tianzhong UHVDC sending grid,this paper analyzes the influence of different DC operating conditions based on effective short circuit ratio （OESCR） ,filter switching and DC single （double）pole lock failure.Then analyzes the impact of frequency adjuster which is at Xinjiang grid on system frequency characteristic;And the influence on UHVDC stability when generator cutting or DC pole blocking faults under the DC isolated operation. The study results show that the operating conditions of the 6 or 8 generators of the DC auxiliary power station can be set up,and the frequency of DC operation is large affected by the frequency adjuster of power grid. But,the DC isolated system frequency stability and transient overvoltage problems are easy to be caused by the DC generator cutting and DC single pole lock failure when considering non control measures. Therefore,it should take stability control strategies or DC power emergency control to enhance the security and stability of the UHVDC system.