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基于虚拟直流电机的直流微网一致性控制策略

Consistent Control Strategy for DC Microgrids Based on Virtual DC Motors

  • 摘要: 为提升含分布式储能系统的直流微网控制的惯性支撑,设计了以虚拟直流电机(VDCM)为核心的控制策略。首先通过分析得到VDCM在电压环没有积分作用下本身具有下垂特性,然后针对SOC均衡控制问题,提出了具有自适应VDCM电枢电阻系数的控制策略,实现电枢电阻系数在SOC偏差指数作用下的自适应调整,达成了SOC均衡控制和功率均分目标。为了实现分布式储能单元的即插即用性,同时满足电压回路和SOC均衡控制需要,引入了动态一致性算法,迭代出SOC和储能输出电压均值。所提控制策略在全局上对传统控制策略进行了简化,同时为系统引入了额外的惯性和阻尼,增强了系统在应对负荷投切和光伏不确定时的鲁棒性。仿真试验证明该方法在应对线路阻抗、功率分配、SOC均衡、母线压降等问题的有效性。

     

    Abstract: To improve the inertia support of DC microgrid control containing distributed energy storage system, a control strategy centered on VDCM is designed. Firstly, it is analyzed that the VDCM itself has sagging characteristics without integration in the voltage loop, and then for the problem of SOC equalization control, this paper proposes a control strategy with an adaptive VDCM armature resistance coefficient, which realizes that the coefficient is adaptively adjusted under the action of the SOC deviation index, and achieves the goal of SOC equalization control and power equalization. To realize the plug-and-play nature of the distributed energy storage unit while realizing the voltage loop and SOC equalization control needs, a dynamic consistency algorithm is introduced to iterate out the average value of the SOC and energy storage output voltage. The control strategy proposed in this paper globally simplifies the conventional control strategy while introducing additional inertia and damping to the system to enhance the robustness of load switching and photovoltaic uncertainty. Simulation tests demonstrate the effectiveness of the method in coping with the problems of line impedance, power distribution, SOC equalization, and bus voltage droop.

     

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