基于单相锁相环的高压直流分相触发相位控制

触发相位控制是高压直流系统控制的基础。换流器触发相位控制方式对高压直流性能的影响尤以不对称故障工况下为甚。针对传统分相触发中过零点检测抗干扰性差以及等间隔触发控制自由度低等缺点，提出一种新的基于单相锁相环的分相触发方案，该触发方式的锁相过程对谐波和负序电压干扰具有较强的抑制能力，能够在三相不对称工况下获得更详细的电压相位信息，减小此时各阀实际触发角的差异。最后，利用PSCAD/EMTDC对所提分相触发方式下高压直流稳态和暂态性能进行了仿真测试和分析，结果表明新分相触发对系统稳态性能无不利影响，并可有效降低交流故障恢复过程发生后续换相失败的概率，验证了该分相触发方式的优越性。

Individual Phase Control of High Voltage Direct Current Based on Single-phase Locked Loop

Trigger phase control is the basis for the control of high voltage direct current(HVDC)system. The effect of trigger phase control on the performance of HVDC is very obvious under asymmetric fault conditions. Aiming at the poor anti-interference of zero-crossing detection of traditional individual phase control and the low degree of control freedom for equidistant firing control, an individual phase control scheme based on single-phase locked loop is proposed. The phase-locked process of the proposed method has strong ability of suppressing harmonics and negative sequence voltage interference, and can obtain more detailed voltage phase information under asymmetrical conditions which reduces the difference of actual trigger angle of each valve. Finally, the stability of HVDC and transient performance under the condition of proposed method are tested and analyzed with PSCAD/EMTDC. The simulation results show that the new individual phase control has no adverse effect on the stability of HVDC, and effectively reduces the probability of commutation failure during AC fault recovery, which verifies the superiority of the proposed method.