虚拟复阻抗下的低压并联逆变器改进下垂控制策略

Improved Droop Control Strategy for Low Voltage Parallel Inverter under Virtual Complex Impedance

线路参数以阻性为主的逆变器并联系统中,通过在传统的P-f/Q-U下垂控制中引入虚拟阻抗实现负荷均分控制,会导致系统总阻抗增大,造成线路电压的进一步下降。针对上述问题,提出了一种基于虚拟复阻抗的改进下垂控制策略。通过设计虚拟复阻抗的值达到功率解耦的目的,并对下垂控制环进行改进。通过仿真结果分析,采用自适应下垂控制及电压补偿的方法,实现了微电网的电压补偿及功率均分,提高了电压质量,并保证系统频率在稳定的范围内波动,加快了系统的动态响应,提高了系统的稳定性。

In the parallel inverter system where the circuit parameters are mainly resistive,load sharing control is realized by introducing virtual impedance into the traditional P-f/Q-U droop control,causing an increase in the total impedance of the system and the voltage drop on the line.Targeting the problems outlined above,the paper proposes an improved droop control strategy based on virtual complex impedance,designs the value of the virtual complex impedance to implement power decoupling,and improves the droop control loop.The simulation results show that the voltage compensation and power sharing in microgrid is realized by using the improved adaptive droop control and voltage compensation method,and the voltage quality is improved,ensuring the system frequency fluctuation within the normal range.Meanwhile the dynamic response of the system is accelerated and the stability of the system is improved.