交流系统故障对特高压直流输电换相失败的影响

Impact of AC system fault on UHVDC commutation failure

研究了多馈入直流系统换相失败的机理,分析了不同类型交流故障下换相失败的特征。针对金沙江±800 kV级特高压直流输电(UHVDC)工程建立仿真模型,研究了金沙江送出工程逆变侧交流系统单相永久故障、三相故障以及三相故障单相拒动对UHVDC换相失败的影响,结果显示:逆变侧交流系统故障越严重、电压波动越大,直流发生换相失败的时间越长;直流发生换相失败期间,最低输送功率越高,对系统保持稳定越有利;故障点距离直流逆变站越近,直流受到的扰动越大,直流换相失败期间输送的功率越低。指出影响直流动态性能的因素应包括直流控制保护系统和直流送、受端接入系统的网络结构。

The commutation failure of multi-infeed HVDC transmission system is researched and its features under different AC fault types are analyzed. A simulative model is established for Jinshajiang ±800kV UHVDC（Ultra High Voltage Direct Current transmission） system,and the impacts of single-phase permanent fault, three-phase short-circuit fault and three-phase short-circuit fault with single-phase trip failure at the inverter side on UHVDC commutation failure are simulated. Results show that, the more serious the AC system fault is or the larger the AC voltage fluctuation is, the longer the commutation failure time will be. During HVDC/UHVDC commutation failure period, the higher the lowest transmission power is, the more stable the system will be. The nearer to UHVDC inverter station the fault is,the larger the impact and the smaller the power transmitted by UHVDC will be. It is pointed out that, the factors influencing the UHVDC dynamic performance include the DC control and protection system and the AC network structure at inverter side.