张北数据港柔性变电站DC/AC变流器关键控制策略

Key Control Strategy for DC/AC Converter in Flexible Substation in Zhangbei Data Center

柔性直流输电是实现新能源并网和直流电网的极具潜力的输电方式。文中在张北数据港设计构造了一台柔性直流输电系统用DC/AC变流器。所设计的变流器采用多变流器并联+z型接地变压器结构。为抑制离网下由于负荷特性而造成的输出电压不平衡与输出电压畸变问题,分别提出了变流器输出电压不平衡控制策略与输出电压谐波抑制策略,以保证设备的供电质量。为保证设备的不间断供电并提高设备的供电可靠性,提出一种主动限流控制策略,在设备离网供电模式下电力系统发生短路故障时进行主动限流。最后,搭建了2.5MW DC/AC变流器进行实验研究。实验结果验证了所提控制策略的有效性。目前,该装置已应用于张北数据港柔性变电站。

The voltage source converter based high voltage direct current (VSC-H VDC) technology is a potential transmission method for new energy grid-connection and DC grids.A DC/AC converter for VSC-HVDC transmission system is designed and constructed in Zhangbei data center.The designed DC/AC converters adopts the structure of paralleled multi-converter+z-type grounding transformer.In order to suppress the output voltage unbalance and output voltage distortion caused by load characteristics in the off-grid mode,an unbalance control strategy and a harmonic suppression strategy of converter output voltage are proposed to ensure the quality of power supply.In order to ensure the uninterrupted power supply and improve the power supply reliability of the equipment,an active current-limiting control strategy is proposed to limit the current actively when the power system has a short-circuit fault in the off-grid power supply mode.Finally,a 2.5 MW DC/AC converter is built for experimental research.The experimental results verify the effectiveness of the proposed control strategy.The designed converter has been applied to the flexible substation in Zhangbei data center.