基于滤波规则的HVDC交流过电压快切滤波器控制策略

高压直流输电的换流器采用晶闸管作为开关器件,在传送有功功率的同时需要消耗大量的无功功率,因此需要配置无功补偿设备。如果换流器发生闭锁、紧急停运、功率回降或者连续换相失败,无功补偿设备不能及时切除,很容易产生交流过电压。传统的根据绝对最小滤波器和最小滤波器投切顺序表的交流过电压快切滤波器控制策略只能按顺序实现单组切除,严重故障时如果不迅速切除可能会引起直流闭锁。提出一种基于滤波规则的交流过电压快切滤波器控制策略,一次计算得到不同类型滤波器的切除数目,实现同时切除多组交流滤波器。仿真试验对两种控制策略进行了对比,仿真结果表明所提控制策略切除速度更快,抑制过电压效果更好。

Filtering-rule-based Control Strategy of Switching-off AC Filters for Overvoltage in HVDC Transmission

The thyristor is widely applied in the line-commutated-converter(LCC)HVDC. As a result, the LCC HVDC consumes a large amount of reactive power when it transmits the active power. If the block, emergency stop, power runback or continuous commutation failure occurs in the converter, it is easy to produce AC overvoltage that the reactive power compensation devices cannot be removed in time. Although the traditional control strategy based on the switching sequence table of the absolute minimum filter and minimum filter can switch off filters one by one, it may cause HVDC block in the severe fault condition because of the slow excision. In this paper, a filtering-rule-based control strategy for switching off two or more filters once is proposed, which is implemented by calculating the cutting-off numbers of different filter types. The above two control strategies are compared in the simulation. It shows that the filters can be removed fast and the AC overvoltage can be suppressed effectively for the filtering-rule-based control strategy.