考虑恒功率负荷特性的直流微电网分级稳定控制策略

Hierarchical Stability Control Strategy of DC Micro-Grid Considering Constant Power Load Performance

已有直流微电网的稳定性研究主要集中在各组成单元的控制器设计上,缺乏系统层面的稳定性分析。随着恒功率负荷的比例增加,其表现出的负阻特性对系统稳定性的影响不容忽视。基于此,该文建立下垂控制下适用于多储能换流器并联的直流微电网系统的等效模型,并在对系统的稳定性问题充分探讨的基础上,提出分级稳定控制方法。考虑系统的非线性,首先对系统可能存在的平衡点进行稳定性判定;其次分析恒功率负荷、系统参数等对稳定性的影响,并对不同系统参数条件下系统的带负载能力进行量化;最后根据理论分析的结果设计分级稳定控制策略,并结合直流微电网系统进行了仿真及实验验证。

The stability research of DC micro grid mainly focuses on the controller design of all components,and lacks adequate analysis at the system level.With the high proportion penetration of constant power load,the negative resistance characteristic cannot be ignored.Therefore,this paper established an equivalent model of large capacity DC micro grid system with droop control suitable for parallel connection of multiple energy storage converters,and discussed the stability of the system.Considering the nonlinearity of the system,this paper firstly determined the stability of the system equilibrium point.Secondly,the influence of constant power load and system parameters on the stability of the system was analyzed,and the load carrying capacity of the system under different system parameters was quantified and verified by simulation.Finally,a hierarchical stability control strategy was designed according to the results of theoretical analysis,including three aspects:initial parameter selection,virtual resistance adjustment and load adjustment.The simulation and experimental verification were carried out.