抑制直流后续换相失败的自适应触发角补偿控制

高压直流输电系统的后续换相失败对交直流混联电网的安稳运行带来严重影响。为降低后续换相失败的发生概率,本文结合首次换相失败后故障恢复过程中直流系统的功率恢复速度,并考虑交流故障严重程度,提出一种抑制直流后续换相失败的自适应动态调节触发角的控制方法。首先,分析了故障恢复过程中各电气量的变化规律以及后续换相失败发生的影响因素；然后根据直流功率恢复速度以及交流电压跌落程度,通过所提控制策略对故障期间逆变侧输出触发角进行动态调整,以增大换相裕度,从而抑制直流后续换相失败。最后,基于CIGRE标准测试模型对控制方法进行仿真验证。结果表明,采用所提自适应触发角补偿控制方法能够在一定程度上抑制后续换相失败的发生,有效改善HVDC系统的故障恢复特性。

Adaptive firing angle compensation control for mitigating DC subsequent commutation failure

Subsequent commutation failure of the HVDC transmission system has a serious impact on the stable operation of the AC-DC hybrid power grid. In order to reduce the probability of subsequent commutation failure, this paper com-bines power recovery rate of the DC system during the failure recovery process after the first commutation failure, and considering the severity of the AC faults, proposes a control method to adaptively adjust the firing angle for suppression of the subsequent commutation failure. Firstly, the law of the electric quantity change during the fault recovery process and the factors affecting the subsequent commutation failure are analyzed. Secondly, according to the power recovery rate and the AC voltage drop, the trigger angle of the inverter side during the fault is dynamically adjusted by the proposed control strategy to increase the commutation margin, thereby suppressing the subsequent commutation failure for HVDC. Finally, the control method is simulated and verified based on the CIGRE benchmark model of HVDC. The results show that the proposed adaptive trigger angle compensation control method can suppress the occurrence of subsequent commutation failure to a certain extent, and the fault recovery performances of HVDC can be improved effectively.Keywords: HVDC; subsequent commutation failure; fault recovery; adaptive firing angle