交流故障下高压直流运行特性及恢复策略研究

Research on Operational Characteristics and Recovery Strategy of HVDC Under AC Fault

充分利用高压直流输电系统自身良好的可控性和快速的响应能力,对改善高压直流系统的恢复性能有着重要意义。该文先通过分析直流电流指令值、交流母线电压与换流站无功功率三者间的关系,提出在以换流站无功交换量为某期望值的前提下根据交流母线电压求取直流电流指令的方法;接着,基于瞬时无功理论计算出交流滤波器的无功补偿量并确定换流器无功消耗量的期望值,再根据高压直流准稳态计算公式和换流器触发角运行范围获得不同故障类型下直流电流最大值与交流母线电压间的约束关系,该直流电流最大值再与上述求出的电流指令取小,就获得最终的直流电流指令;最后,在CIGRE高压直流标准测试模型和贵广II高压直流模型上对文中所提恢复策略在抑制后续换相失败、改善系统恢复性能等方面的有效性和鲁棒性进行验证。

It is of great significance to make full use of the good controllability and the fast response ability of the high voltage direct current(HVDC) transmission system to improve the recovery performance of the HVDC system. First, by analyzing the relationship between the DC current instruction value, the AC bus voltage and the reactive power of the converter station, the rule of DC current instruction changing with AC bus voltage was obtained under the premise of setting the reactive power exchange of the converter station as a desired value. Next, based on instantaneous reactive power theory, the reactive power compensated by AC filter was calculated and the expected value of reactive power consumption in converter station was determined. By using the quasi-steady state calculation formula of HVDC, the constraint relation between the maximum DC current value and the AC voltage under different fault types was obtained by determining the limit range of the trigger angle. Finally, the superiority and effectiveness of the proposed recovery strategy in this paper were verified on the CIGRE HVDC model and the Gui Guang II HVDC model in terms of restraining the subsequent commutation failure and improving the system recovery performance.