基于无功电压补偿优化的VSG环流抑制策略

VSG Circulating Current Suppression Strategy Based on Reactive Voltage Compensation Optimization

针对现有的抑制策略超调量大、抑制环流效果差的问题,提出基于无功电压补偿优化的VSG环流抑制策略。由于并联系统中线路阻抗分布不同,使得VSG端口输出电压存在差异,系统产生环流,因此需分析系统的功率传输特性。首先计算逆变器的并网环流,并用三维图像表示;然后对图像进行分析;再建立同步发电机模型,对VSG输出功率进行调节,运用带电压补偿的VSG控制策略来进行抑制,调节下垂系数,设计补偿的电压量,修正VSG电压差值达到抑制效果。实验结果表明,实验组调节RG2与RG1具有相同的电压,有效控制不发生超调,减少了振荡发生,使得达到目标电压的时间更短,状态更稳定。

In view of the large overshoot and the poor suppression effect of existing suppression strategies,a VSG circulation suppression strategy based on reactive voltage compensation optimization is studied.Due to the different distribution of line impedance in parallel systems,there are differences in the output voltage of VSG ports,resulting in circulating currents in the system.Therefore it is necessary to analyze the power transmission characteristics of the system.First the grid-connected circulating current of the inverter is calculated and represented with a three-dimensional image which is then analyzed.Further a synchronous generator model is established,which adjusts the output power of VSG,uses VSG control strategy with voltage compensation for suppression.The desired suppression utility is achieved by adjusting droop coefficient,determining compensation voltage value,and correcting VSG voltage difference to achieve suppression effect.The experimental results show that RG2 and RG1 adjustment by the proposed strategy have the same voltage,effectively controlling the occurrence of overshoot,reducing oscillation,achieving the target voltage in a shorter time,and maintaining a more stable state.