电-氢多能互补型微电网的VSG平衡电流控制方法

Balanced Current Control Method for Virtual Synchronous Generator in Electro-Hydrogen Multi-Energy Complementary Microgrid

多能互补型微电网将具有互补性的多种能源集中于同一并网系统,可有效提高微电网的能源利用效率及供电可靠性.虚拟同步发电机(virtual synchronous generator,VSG)技术,实现分布式电源的友好并网.然而,在非理想运行情况下,当电网电压出现不平衡时,传统的VSG控制不具备抑制负序电流的能力,将导致微电网三相并网电流不平衡,因此提出一种基于电-氢多能互补型微电网的VSG平衡电流控制方法.本文搭建了包含光伏及储能系统的电能系统模型,和包含电解槽-氢储能-燃料电池系统的氢能系统模型;分析了VSG的基本原理,通过VSG并网小信号模型的分析,对控制参数进行了设计,提高了系统的稳定裕度;定量分析了不平衡电流的产生原因,通过改进dq坐标系下电流指令计算方法,抑制了负序电流,保证电-氢多能互补型微电网的电能质量.最后仿真验证了多能互补微电网能量管理策略的有效性,仿真结果证明VSG平衡电流控制方法能在电压不平衡情况下实现并网电流三相平衡,最终将冲击电流由52 A抑制至27 A,并显著减小了功率波动.

The multi-energy complementary microgrid concentrates multiple complementary energy sources in the same grid-connected system,which can effectively improve energy utilization efficiency and power supply reliability of the microgrid. Virtual synchronous generator(VSG) technology enables friendly networking of distributed power supplies. However,in the case of non-ideal operation,the traditional VSG control does not have the ability to suppress the negative sequence current when the grid voltage is unbalanced,which will lead to the imbalance of the three-phase grid-connected current of the microgrid. To solve this problem,a VSG balanced current control method based on electro-hydrogen multi-energy complementary microgrid is proposed. This work builds a power system model including photovoltaic and energy storage systems,and a hydrogen energy system model including an electrolytic cell-hydrogen storage-fuel cell system. Then, the basic principle of VSG is analyzed,and through the analysis of the VSG grid-connected small-signal model,the system parameters and control parameters are designed to improve system stability margin. The causes of the unbalanced current are shown in a way of quantitative analysis. In addition,by improving the current command calculation method in the dq coordinate system,it is able to suppress the negative sequence current and ensure the power quality of the electro-hydrogen multi-complementary microgrid. Finally, the energy management strategy of multi-energy complementary microgrid is verified to be effective by simulation. The simulation results show that the VSG balanced current control method can achieve the three-phase balance of the grid-connected current in the case of voltage imbalance and the inrush current is suppressed from 52 A to 27 A. Furthermore,it significantly reduces power fluctuations.