分布式微电网自同步电压源并列运行策略

分布式能源的高渗透率使集中式微电网的弊端逐渐显现,因此分布式微电网受到广泛关注。针对目前分布式微电网中鲜有关注的微源与交流母线连接线路末端的功率耦合及下垂系数不可控问题,基于控制量本地性原则,提出考虑下垂系数精确控制的改进VSG控制策略,实现线路末端功率解耦及期望的下垂特性。然后,结合虚拟转子特性匹配方法,在无需附加改进无功控制的前提下,从静态与动态两个角度实现各并联逆变器功率的合理分配。最后,基于Matlab/Simulink仿真平台验证该方法的有效性与可行性。所提控制策略与匹配原则使逆变器具备自同步特性,形成自同步电压源,赋予分布式微电网较高的自稳性、自主性以及鲁棒性,保证微电网的稳定运行。

Operation strategy of parallel self-synchronizing voltage sources in a distributed microgrid

A centralized control mode is no longer applicable for microgrid operation because of the high penetration rate of distributed energy. This fact is responsible for the widespread interest in the use of a distributed microgrid. This paper examines the issues, rarely considered, of power coupling and uncontrollable droop coefficient at the terminal of the connection line between micro-source and AC bus. An improved VSG control strategy is proposed based on local data considering precise control of droop coefficient, realizing the power decoupling and the expected droop characteristics. Then, combined with a virtual rotor characteristic matching method, the reasonable active and reactive power sharing of the parallel microgrid inverters are realized in terms of static and dynamic performance without additional improvement of reactive power control. Finally, the effectiveness and feasibility of the proposed method are verified on the Matlab/Simulink simulation platform. The combination of the proven strategy and matching principle endows inverters with self-synchronization characteristics, forming the self-synchronizing voltage sources. This all gives the distributed microgrid a higher self-stability, autonomy and robustness to ensure stable operation of the microgrid. This work is supported by Natural Science Foundation of Hebei Province (No. E20185021134) and Science and Technology Project of the Headquarter of State Grid Corporation of China (No. SGTYHT/18-JS-206).