基于自适应虚拟电容的改进VSG无功功率分配控制策略

Improved VSG Reactive Power Distribution Control Strategy Based on Adaptive Virtual Capacitor

  • 摘要: 在分布式电源(Distributed generation,DG)并联运行的孤岛微电网中,通常采用虚拟同步发电机(Virtual synchronous generator,VSG)控制来应对系统惯量和阻尼不足的问题。然而,由于线路阻抗不匹配,各DG难以实现无功功率的合理分配,而传统的控制方法始终无法解决无功功率精确分配和母线电压恢复之间的矛盾。针对这一问题,在分析并联VSG功率分配机理的基础上,提出一种自适应虚拟电容控制策略。该策略将VSG输出的无功功率差值和电压差值结合到一致性算法的设计中,能够对母线电压进行自适应补偿,同时实现电压恢复和无功功率按比例精确分配的控制目标。最后,基于Matlab/Simulink搭建了四台VSG仿真模型,分别对传统虚拟电容VSG控制和引入自适应虚拟电容VSG控制进行仿真对比,验证所提自适应控制策略的可行性与有效性。

     

    Abstract: In island microgrids where distributed power sources(DGs) operate in parallel, virtual synchronous generator(VSG) control is usually used to deal with the problem of insufficient system inertia and damping. However, due to line impedance mismatch, it is difficult for each DG to achieve reasonable distribution of reactive power, and traditional control methods have never been able to solve the contradiction between accurate distribution of reactive power and bus voltage recovery. To address this problem, an adaptive virtual capacitor control strategy is proposed based on the analysis of the power distribution mechanism of parallel VSGs. This strategy combines the reactive power difference and voltage difference output by the VSG into the design of the consistency algorithm, which can adaptively compensate the bus voltage while achieving the control goals of voltage recovery and accurate distribution of reactive power in proportion. Finally, four VSG simulation models are built based on the Matlab/Simulink, and the traditional virtual capacitor VSG control and the introduced adaptive virtual capacitor VSG control are simulated and compared to verify the feasibility and effectiveness of the proposed adaptive control strategy.

     

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