基于坐标旋转虚拟阻抗的微电网控制与性能分析

微电网中系统阻抗不平衡和复阻抗特性、电源和负载位置复杂性等因素严重影响了系统功率分配的准确性、稳定性和动态性能。提出了基于坐标旋转虚拟阻抗的孤岛微电网控制策略,采用坐标旋转虚拟阻抗闭环改善微电网的阻抗特性,基于电压幅值和频率下垂控制实现系统功率分配,带前馈补偿的电压外环控制和电流内环控制保证了系统的稳态和暂态性能。建立了完整的微电网小信号动态模型,并在此基础上分析了坐标旋转虚拟阻抗对整个微电网性能的影响。算例仿真验证了小信号动态建模分析的准确性,证明了该方法能够改进功率解耦和分配的准确性,提高微电网控制的稳定性和动态性能。

Control and performance analysis of microgrid based on coordinate rotational virtual impedance

The power-sharing accuracy, system stability and transient performance can be seriously influenced by the unbalanced complex impedance, the complicated location of power generations and loads in microgrid. The control strategy of autonomous microgrid based on coordinate rotational virtual impedance is proposed to handle this problem. The coordinate rotational virtual impedance loop is adopted to improve the impedance characteristic. The system power-sharing is implemented by voltage magnitude and frequency based droop control strategy. The system stability and transient performance is ensured by the outer voltage control loop and inner current control loop with feed-forward compensation. In order to analyze the effect of coordinate rotational virtual impedance on the performance of microgrid, the small-signal dynamic model of whole microgrid is built. The simulation results verify the accuracy of small-signal dynamic modeling and analysis, confirming that the proposed control strategy can improve the active and reactive power decoupling, the power sharing accuracy, and the system stability and transient performance.