基于虚拟电抗的微电网改进下垂控制策略

Improved droop control strategy for microgrid based on virtual reactance

由于微电网线路阻抗参数呈阻感性且线路阻抗分布不均,从而影响到下垂策略对系统的精确控制以及功率的合理分配。为此,利用相对增益矩阵分析了微电网中存在的功率耦合,提出一种基于虚拟电抗的改进下垂控制方法。该方法通过引入虚拟电抗,使逆变器输出阻抗变为感性,减小线路参数带来的功率耦合,实现微电网线路的有功功率与无功功率的独立控制。同时通过改进下垂控制,使之根据无功分配需求自适应调节下垂系数,进一步消除因线路阻抗不平衡导致的逆变器输出无功功率偏差,并且减小了并联线路间的电流差值,抑制了环流,提高了系统运行的可靠性与稳定性,实现了下垂策略对系统的精确控制以及功率的合理分配,为微电网中能源并联提供了参考控制策略。

Due to the impedance parameters of microgrid lines being resistive and the uneven distribution of line impedance,it affects the precise control of the system by the droop equation and the reasonable allocation of power.Therefore,this article uses the relative gain matrix to analyze the power coupling in microgrids and proposes an improved droop control method based on virtual reactance.This method introduces virtual reactance to convert the output impedance of the inverter into inductance,reducing the power coupling caused by line parameters,and achieving independent control of active and reactive power of microgrid lines.At the same time,by improving the droop control to adaptively adjust the droop coefficient according to the reactive power allocation requirements,further eliminating the deviation of reactive power output from parallel inverters caused by line impedance imbalance,and reducing the current difference between parallel lines,the circulating currents is suppressed,the reliability and stability of system operation are improved,achieving precise control of the droop strategy on the system and reasonable power allocation,providing a reference control strategy for energy parallel connection in microgrids.