孤岛运行微网中分布式谐波功率分配控制策略

Distributed Harmonic Power Sharing Control Strategy in Islanded Microgrids

微电网中分布式发电可用于在接有非线性负荷的情况下增强电能质量。由于线路阻抗不匹配,传统上基于固定虚拟阻抗的下垂控制方法难以按分布式发电容量比例精准分配负荷谐波功率,且传统的集中式控制方法存在可靠性低、单点故障会导致谐波功率无法准确分配等问题。基于以上问题,提出了一种基于一致性算法动态调节虚拟阻抗的分布式谐波功率均分控制方法。该方法通过应用多智能体理论设计了一致性算法来自适应调整谐波虚拟阻抗,从而消除线路阻抗不匹配带来的影响,实现了分布式发电单元按容量精确分配负荷谐波,极大地降低了公共连接点的电压谐波含量。同时,分布式的方法消除了集中控制器的不足,提高了系统运行的可靠性和灵活性。仿真结果验证了该控制方案的正确性和有效性。

Distributed generations （DGs） can be used for the power quality enhancement of islanded microgrids with the nonlinear load. Due to mismatched line impedance, the harmonic power among DGs could not be shared in proportion to DG rating by using the conventional droop control with constant virtual impedance. Also, with centralized control, the harmonic power among DGs could not be shared accurately because of low reliability due to its signal point of failure features. To cope with this problem, this paper proposes a distributed harmonic power sharing method based on both consensus and adaptive virtual impedance. The proposed method adaptively adjusts the harmonic virtual impedance by using the consensus control algorithm based on the multi-agent theory to compensate the mismatched line impedance, achieving accurate harmonic power sharing among the DGs and reduced voltage harmonic distortion at the point of common coupling （PCC）. Meanwhile, the requirement of a centralized controller is obviated and the system reliability and flexibility are improved. The effectiveness of proposed control scheme is verified through simulation results.