直流微网DC/DC变换器的虚拟直流电机控制策略研究

直流微网是小惯性系统,负荷频繁投切和新能源出力波动等因素都会影响母线电压的稳定。在直流微网系统中,往往通过储能单元维持系统功率平衡和母线电压稳定。针对储能端口双向DC/DC变换器,提出一种简化的虚拟直流电机控制方法,以增强系统的惯性和阻尼;建立虚拟直流电机控制的小信号模型,分析控制策略的稳定性和动态特性;对于动态响应初期母线电压的冲击性变化,提出输出电流前馈的小信号模型补偿方法,进一步平滑母线电压的动态过程;最后通过仿真分析验证了所提控制策略的正确性和有效性。

Research on Control Strategy of Virtual DC Machines for DC/DC Converter in DC Microgrid

The DC microgrid is a system with low inertia,where frequent load switching and fluctuation of new energy output affect the stability of the bus voltage. In DC microgrid systems,energy storage units are often used to maintain system power balance and bus voltage stability. Aiming at the bidirectional DC/DC converter of the energy storage port,this paper proposes a simplified virtual DC machine control method to enhance the inertia and damping of the system. This paper also establishes a small signal model for virtual DC machine control,and analyzes the stability and dynamic characteristics of the control strategy. For the impulse change of the bus voltage at the initial stage of dynamic response,a small-signal model compensation method for output current feedforward is also proposed to further smooth the dynamic process of bus voltage.Finally,the simulation analysis has verified the correctness and effectiveness of the proposed control strategy.