一种孤岛微网中均分不平衡功率的控制方法

An Unbalanced Power Sharing Control Method for Islanded Microgrids

针对传统下垂控制不能均分不平衡功率的问题,提出一种基于小信号注入的控制方法,可以实现不平衡功率的均分。该方法由传统的P-ω,Q-E下垂控制模块、负序虚拟阻抗控制模块、以及不平衡功率到小信号频率(S_U-ω_(as))所建立的下垂控制模块三部分组成。传统下垂控制模块用于实现有功功率和无功功率的均分;负序虚拟阻抗控制模块可以调节不平衡功率在并联逆变器之间的分配;S_U-ω_(as)下垂控制模块可以自动调整负序虚拟阻抗幅值的大小,保证稳态时不平衡功率完全均分,或者按照各台逆变器的容量均分。该控制方法各台逆变器之间不需要任何通讯,也无需测量线路阻抗。仿真及实验结果验证了该方法的有效性。

Aiming at the problem that the traditional droop control can not divide the unbalanced power, a control method based on small signal injection is proposed, which can achieve the equalization of unbalanced power.The pro- posed method consists of typical real-power-frequency （P-w） and reactive-power-voltage （Q-E） droop control,virtual impedance control which only functions at fundamental negative sequence,and unbalanced-power-small-signal-fre- quency（Su-w,） droop control.The typical droop control can ensure the sharing of real and reactive power.The negative sequence virtual impedance is introduced to regulate the distribution of unbalanced power.The proposed Su-ωm droop relationship, which is based on the injection of an independent small AC signal, is added to completely compensate the unbalanced power sharing error.This novel method does not employ any communication links among the distributed generation units, and it does not need the information of feeder impedance.Simulation and experimental results are provided to validate the proposed method.