基于改进下垂控制的孤岛微网逆变器并联技术研究

Reserch on Parallel Technology of Island Microgrid Inverters Based on Improved Droop Control Method

逆变器并联系统在等效输出阻抗呈阻性条件下无法适用传统下垂控制方法,在对逆变器并联系统功率分配精度影响因素,以及传统下垂控制方法分析的基础上,提出了一种改进下垂控制方法。该方法首先利用虚拟复阻抗解决系统等效输出阻抗呈阻性条件下下垂控制的适用性问题,然后针对由此产生的电压跌落和频率偏差问题,提出了一种结合积分补偿器的功率二次函数项变下垂系数改进控制方法,并引入电压和频率微分调节器改善系统动态调节性能。最后通过仿真验证了该改进下垂控制方法在孤岛微网条件下的有效性和可靠性。

The inverter parallel system cannot apply the traditional droop control strategy under the condition that the equivalent output impedance is resistive.Based on the analysis of the factors influencing the power distribution accuracy of inverter parallel system and the traditional droop control strategy,an improved droop control method was proposed.Firstly,a method of virtual complex impedance was used to solve the problem of droop control under the condition that equivalent output impedance of the system is resistive.Then,an improved control method combining the variable droop coefficient of the power quadratic function term combined with the integral compensator was proposed for the voltage and frequency drop problem,and the differential regulator was introduced to improve the dynamic performance of the system.Finally,the simulation results verified the effectiveness and reliability of the improved droop control method under island microgrid conditions.