一种应用于直流微电网的改进型下垂控制策略

Research on a new improved droop control method for DC microgrid

在直流微电网中,下垂控制是解决多微源系统下负荷功率分配问题的基本控制方法之一。传统下垂控制策略是基于定下垂系数的U-I下垂控制方法。该方法虽然可靠性和经济性较好,但由于系统中各微源到负载端的线路阻抗不完全相同,导致各微源对负载的输出功率不能合理分配。为此,本文提出一种基于电压偏移补偿控制和电流分配补偿控制的改进下垂控制方法。该方法利用变换器输出电压、电流平均值来校正各变换器的输出电压与电流,从而达到减小母线电压降落和提高变换器电流分配精度的目的。本文对该控制方法分别在线路阻抗不一致和公共负载波动的工况下进行了仿真,其结果验证了该控制策略的有效性。

In the DC microgrid, droop control is one of the basic control methods to solve the problem of load power distribution in multi-micro source systems. The traditional droop control strategy is the U-I droop control which is based on fixed droop coefficient. Although this method has good reliability and economy, the output power of each micro-source to the load can’t be allocated reasonably because the line impedance of each micro-source to the load end is not identical. Therefore, an improved droop control method based on voltage offset compensation control and current distribution compensation control is proposed. The average value of output voltage and current of each converter is used to correct the output voltage and current of each converter in this method, so as to reduce bus voltage drop and improve the accuracy of current distribution of the converter. The control method is verified by simulation under the conditions of inconsistent line impedance and common load fluctuation respectively, and the results verify the effectiveness of the control strategy.