电力电子技术

直流微电网中,由于电流分配可能因线路阻抗变化而不准确,传统下垂控制难以兼顾功率分配精度和电压控制准确性。为了解决该类问题,本文提出了一种基于自适应参数补偿下垂控制的直流微网分层控制策略,该策略包括底层控制和顶层控制两部分:顶层控制计算多个变流器端口的设定电流作为控制输入,并根据输入电流值自适应计算母线电压补偿量与下垂系数补偿量,对下垂控制造成的母线电压偏差、电流分配不均效果进行修正;底层控制则接收顶层控制的输出,控制开关信号来调整电压电流输出。通过所提出的控制策略,可以同时确保母线电压稳定和功率均分,更好地协调直流微电网的运行。最后通过仿真模型和实验对比了所提方法相较于传统下垂控制策略,实验结果显示改进的下垂控制策略在阻性负载跳变的情况下可以将母线电压稳态误差维持在1%以内,并实现电流均分,而传统下垂控制误差在10%以上,无法均分电流,实验与仿真均验证了所提改进策略的可行性与优越性。

In traditional droop control,there is a conflict between power distribution and voltage regulation,and current distribution may become inaccurate due to variations in line impedance.To address these issues,an improved droop control strategy for DC microgrids to overcome the limitations of traditional droop control is proposed.An adaptive parameter compensation droop control strategy based on hierarchical control is introduced.This strategy comprises two parts:primary control and secondary control.The primary control calculates the current for multiple converter ports and adaptively computes the bus voltage compensation and droop coefficient compensation based on the input current values,it corrects the bus voltage deviation and uneven current distribution caused by droop control.The secondary control receives the output from the primary control and outputs PWM signals to regulate the voltage and current output.This new control method better coordinates the operation of DC microgrids.Finally,through the simulation model and experimental method compared with the traditional droop control strategy,the experimental results show that improved droop control strategy in the case of resistive load step-change can maintain the bus voltage steady-state error within 1%,and realize the current distribution,and the traditional droop control error above 10%,cannot divide current,experiment and simulation verify the feasibility and superiority of improvement strategy.