电网电压对称骤升下双馈风力发电系统的改进控制策略研究

Improved Control Strategy for a Double-fed Generation System Under Grid Voltage Symmetric Swell

该文基于双馈风电机组(doubly-fed induction generator,DFIG),在电网电压对称骤升下,对电网电压与转子电流之间的暂态过程进行详细的理论推导,提出一种有效抑制转子过电流的控制策略,并针对网侧变换器传统控制方法作出相应的改进。在不增加任何硬件设备的情况下,转子侧和网侧分别附加转子电流抑制(rotor current suppression,RCS)和外环电网电压控制(grid voltage suppression,GVS)措施,并给出详细的控制框图。该控制方法不仅可以减少Crowbar装置频繁动作致使转子侧变换器快速短接的问题,而且充分发挥风电机组自身的动态无功支撑能力,保证风电机组在电网电压故障骤升期间不脱网运行,有效提高双馈风力发电机的高电压穿越(high voltage ride through,HVRT)能力及风电机组运行的可靠性。最后,在PSCAD/EMTDC中对所提出的控制策略进行仿真建模分析,验证了该控制方案的有效性和可行性。

This paper derives the transients between the grid voltage and the rotor current of doubly-fed induction generator(DFIG) under grid voltage symmetric swell. An effective control strategy aiming to restrain rotor over-current is proposed and the traditional control strategy of the grid-side converter is also improved. Without adding any other power electronic devices, the proposed method with both the rotor current suppression(RCS) and the grid voltage suppression(GVS) can not only solve the problem of short-circuit of the rotor side converter resulting from the frequent switching of the Crowbar device, but also maximally improve the capability of wind turbine in dynamic reactive power support. This control strategy can make sure that the wind turbine is able to maintain its normal operation even during the fault and at the same time the high voltage ride through(HVRT) capability of wind turbine can be achieved. As a result, the operation reliability of the wind turbine is significantly improved. Finally, the simulations and analysis results in the PSCAD/EMTDC verify the effectiveness and feasibility of the proposed control scheme.