适应大容量直流接入弱受端的直流极控系统优化控制方法

大容量直流接入较弱受端系统,换流母线电压相对敏感,故障扰动易引起直流换相失败甚至发生连续换相失败。针对弱受端交流故障恢复过程中可能出现的连续换相失败问题,提出了根据交流系统和直流系统关键变量,在线计算调整低压限流功能直流电压上限值的方法,使直流的恢复速度能适应交流系统的恢复状态,避免连续换相失败的发生;提出了逆变站调节器配合和分接头控制的优化方法,使逆变站进入定直流电压控制模式,能在一定程度上减小远端故障引发换相失败的概率。利用与实际直流工程极控系统完全一致的仿真模型进行仿真验证,仿真结果表明:所提出的优化方法可行、有效,能适应弱受端系统对于抵御换相失败的需求,有利于改善交直流系统运行稳定性。

Optimization methods of pole control system for large-capacity HVDC accessing to weak receiving system

In the case of large-capacity HVDC accessing to weak receiving system, since the converter bus voltage is relatively sensitive, fault disturbance may easily induce commutation failure, even continuous commutation failures. Aiming at the possible continuous commutation failures during the fault recovery process of weak receiving system, a method to on-line calculate the upper DC voltage limit of VDCOL function according to the key variables of AC and DC systems is put forward, which adapts the recovery speed of DC system to the recovery state of AC system to avoid the continuous commutation failures. The optimization methods for the regulator coordination and tap changer control of inverter station are also put forward, which makes the inverter station operating in the constant DC voltage control mode to reduce the probability of commutation failure caused by distal fault. A simulation model of HVDC pole control system in accordance with actual system is built and the simulative results show that, the proposed optimization methods are feasible and effective in meeting the requirement of weak receiving system against the commutation failure and improving the operating stability of AC/DC system.