谐波附加控制抑制直流输电连续换相失败研究

Suppressing HVDC continuous commutation failure by additional harmonic control

换相失败是高压直流输电(HVDC)最为常见的故障之一,而我国特高压直流在控保系统内设置了连续换相失败启动直流主动闭锁的逻辑,连续换相失败及其可能造成的直流闭锁对电网的安全稳定运行造成了一定威胁。国内外关于抑制连续换相失败的研究已经取得部分研究成果,但就谐波对HVDC连续换相失败的影响研究方面还有待进一步深入。文中从HVDC换相过程出发,通过换相电压-时间面积分析法,推导出直流输电附加控制回路的各次谐波控制参数,并考虑低压限流控制对直流输电换相失败恢复过程的影响,提出一种谐波附加控制抑制直流输电连续换相失败的方法。最后,基于CIGRE HVDC标准测试模型,利用PSCAD/EMTDC对所提控制方法有效性进行了仿真验证。

The commutation failure is one of the most common faults in high voltage direct current transmission(HVDC)systems.In China,the control and protection system of ultra-high voltage direct current is provided with the logic of starting active DC blocking to avoid negative influence of continuous commutation failure.However,the possibility of DC blocking which is caused by the continuous commutation failure poses a certain threat to the safety and stability of operation in the power grid.The suppressing HVDC continuous commutation failure has received more attention by researchers around the world.However,the influence of harmonic on the HVDC continuous commutation failure has not been reported thoroughly yet.The method of commutation voltage-time area is applied to analyze commutation process for HVDC transmission,after which harmonic control parameters of additional control loop are obtained.In the recovery process,the influence of commutation failure on voltage dependent current order limiter is taken into account,and a method for reducing failure rate of HVDC continuous commutation with additional harmonic control is proposed.Finally,based on the CIGRE HVDC standard test system,the effectiveness of the proposed control method is verified by PSCAD/EMTDC.