谐波引起的高压直流输电连续换相失败抑制方法研究

高压直流输电系统连续换相失败是引发交直流混联电网连锁故障的重要诱因。谐波造成的电压波形畸变导致换相面积减少,是引发连续换相失败的重要因素。现有换相失败抑制方法研究主要是针对换相电压工频幅值下降,缺乏对谐波影响的考虑。针对该问题,分析了谐波对连续换相失败的影响机理,计算了谐波对关断面积的影响因子,提出了一种考虑谐波的关断角整定值定量计算方法。所提算法在换相失败期间提高关断角控制器的指令值,提高后续阀组的关断裕度,抑制连续换相失败的发生。最后通过电磁暂态仿真软件PSCAD/EMTDC进行验证。算例仿真验证了所提方法的有效性。

Study on HVDC consecutive commutation failures mitigation method caused by harmonics

Consecutive commutation failure of HVDC transmission system is an important cause of cascading faults in AC/DC hybrid power system.The distortion of voltage waveform caused by harmonics leads to the reduction of commutation area,which is an important factor leading to the consecutive commutation failure.The existing methods of commutation failure mitigation are mainly aimed at the decrease of amplitude of fundamental frequency voltage and lack of consideration of harmonic effect.To solve this problem,this paper analyzes the influence mechanism of harmonics on the consecutive commutation failure,calculates the influence factors of harmonics on the extinction area,and proposes a quantitative calculation method of the extinction angle setting value considering harmonics.The proposed algorithm increases the setting value of the constant extinction angle controller during commutation failure and maintains a constant extinction area,thus restraining the occurrence of consecutive commutation failure.Finally,the simulation is carried out by electromagnetic transient simulation software PSCAD/EMTDC.The effectiveness of the proposed method is verified by the simulation.