考虑故障限流的下垂控制型逆变器暂态控制策略

Transient Control Strategy of Droop-Controlled Inverter Considering Fault Current Limitation

下垂控制型逆变器能够为电网提供电压与频率支撑,其安全稳定运行对电网意义重大。然而,在故障工况下,下垂控制型逆变器面临功角失稳与过电流问题,这严重威胁了下垂控制型逆变器的安全运行。目前的研究往往将功角控制与故障电流控制作为两个独立问题进行解决,鲜有研究兼顾功角控制与故障电流控制对下垂控制型逆变器展开综合调控。基于此,首先,对下垂控制型逆变器暂态特性展开分析,详细阐述电流限幅环节与无功-电压环路对逆变器暂态特性的影响。接着,提出兼顾故障限流与功角稳定性的下垂控制型逆变器暂态控制方法。所提方法综合考虑故障期间电网电压与逆变器端电压的变化,通过对有功-频率环路的优化调控实现功角稳定控制。此外,在功角控制的基础上,改进无功-电压环路控制实现故障电流的有效抑制。最后,通过仿真与实验验证了该文所提方法的有效性。

The droop-controlled inverter can provide voltage and frequency support for the power grid,and its transient stability is important.However,the stability of power angle and fault current affects the safe operation of the droop-controlled inverter under fault conditions.In this paper,the transient characteristics of the droop-controlled inverter are analyzed,and the influence of current limiter and Q-U loop on the transient characteristics of the inverter is described in detail.Accordingly,this paper proposes a transient control method for the droop-controlled inverter which takes into account both fault current limitation and power angle stability.The proposed method considers the variation of the grid voltage and the output voltage of the inverter during the fault period and realizes the power angle stability of the inverter by adjusting the active power reference.In addition,the fault current can be effectively suppressed by the optimal control of the Q-U control loop.Finally,the effectiveness of the proposed method is verified by simulation and experiment.