柔性直流输电系统孤岛运行方式下的故障电流抑制方法

结合实际工程需要,针对柔性直流输电系统运行在孤岛状态下发生交流侧故障后容易引起过流跳闸的问题,提出一种柔性直流输电系统在孤岛运行方式下的故障电流抑制和启动控制方法。该方法满足柔性直流孤岛运行方式下各类故障的电流抑制要求,并且可以做到在柔性直流设备自身能力范围内,向交流系统提供预先设定的故障电流,同时可以实现正常升压启动。结合基于控制保护样机和RTLAB构成的闭环实时仿真系统,对提出的方案进行了验证。结果表明,与常规的幅频开环孤岛控制及电流环控制策略相比,所提方案提高了故障穿越能力,且启动策略实现了孤岛运行模式下的无冲击顺利启动。

Fault Current Suppression Method for Flexible DC Transmission System Operating in Islanded Mode

Combined with the actual engineering needs, a fault current suppression and starting-up control method is proposed in view of the problem of over-current tripping after the AC side fault for the flexible DC transmission system operating in islanded mode. The method can satisfy the requirement of suppressing fault current under all kinds of AC faults in the islanded state, provide the preset fault current to AC system within its own capacity of the flexible DC device, and realize the normal startup procedure in the islanded operation state. Based on the real control and protection devices and the real-time closed-loop simulation system constructed by RTLAB, the proposed control strategy is verified. The results demonstrate that the proposed control strategy can improve the fault ride-through capability in contrast to the conventional control strategy, such as the amplitude frequency open-loop island control or the normal closed-loop current control strategy. Meanwhile, the starting-up control realizes the startup without impact in islanded operation mode.