单相跳闸对换相过程的影响机理及连续换相失败抑制方法

对逆变侧交流系统因接地故障而单相跳闸后换流母线处电压的相位特征进行了研究,理论分析表明交流系统切除故障相将导致逆变器各换相电压的相位差发生变化。在此基础上,对单相跳闸后的逆变器换相过程进行了分析,发现在现有的等间隔触发方式下,直流系统的换相过程将受到影响,甚至面临换相失败的风险。因此,提出了基于触发角偏差量的换相失败判断方法,该方法能够可靠判断当前系统参数下单相跳闸是否会引发连续换相失败。基于换相电压相位差提出了一种适用于逆变侧交流系统单相跳闸后的逆变器触发方式以抑制换相失败。PSCAD仿真结果表明,所提出换相失败判断方法能可靠预测单相跳闸引发的换相失败,所提出的换流器触发方式可以有效抑制连续换相失败。

Influence mechanism of single-phase tripping on commutation process and suppression strategy of continuous commutation failure

The phase characteristics of the voltage at the converter busbar after the single-phase tripping of inverter-side AC system due to the grounding fault are studied. The theoretical analysis shows that cutting the fault phase of AC system will change the phase difference of the inverter commutation voltage. On this basis, the inverter commutation process after single-phase tripping is analyzed, which shows that under the existing equal interval triggering mode, the commutation process of the DC system will be affected, and there is even the risk of commutation failure. Therefore, a commutation failure judgment method based on the amount of trigger angle deviation is proposed, which can reliably determine whether the single-phase tripping under the current system parameters will cause continuous commutation failure. Based on the phase difference of the commutation voltage, an inverter triggering method suitable for the single-phase tripping of inverter-side AC system is proposed to suppress the commutation failure. The results of PSCAD simulation show that the proposed commutation failure judging method can reliably predict the commutation failure caused by single-phase tripping, and the proposed converter triggering mode can effectively suppress the continuous commutation failure.