含异构微源的混合型孤岛微电网暂态有功响应分析与控制策略

Transient Active Power Response Analysis and Control Strategy of Hybrid Island Microgrid Containing Heterogeneous Microsources

在逆变器接口微源(IM)与同步机接口微源(SM)并存的混合型孤岛微电网中,由于两类微源的物理结构与动态特性存在差异,易导致微电网有功负荷投切暂态响应存在初始有功分配不均、响应速度慢的问题。在有功负荷突增场景下,IM在暂态初始阶段中有功输出峰值过高,易触发逆变器限流保护动作。该文首先以IM与SM并联系统为研究对象,分析两类微源有功负荷突增暂态的角频率响应差异,进一步得出造成暂态初始阶段IM输出有功峰值过高的原因。为量化并联系统响应速度,构建并联系统传递函数模型,分析系统主导极点的分布对响应速度的影响。然后,针对混合型孤岛微电网的暂态有功控制策略进行研究。在不引入通信的情况下,引入虚拟电抗法调节初始有功分配,通过控制参数优化加快系统响应速度;在引入通信情况下,提出IM的附加控制方法,实现并联系统暂态有功性能的改善,并将该控制推广到含多台异构微源的混合型孤岛微电网。最后,基于Matlab/Simulink时域仿真验证了该文分析结论与控制策略的有效性。

At present,most of the island microgrid demonstration projects at home and abroad are hybrid island microgrids in which inverter interface microsource(IM)and synchronous machine interface microsource(SM)coexist.There are large differences in physical structure and dynamic characteristics between SM and IM,which causes the hybrid island microgrid to have problems of uneven distribution of active power and slow response speed in the transient response of active load switching,showing poor transient performance.In the scenario of a sudden increase in active load,the IM’s active power output peak value is too high in the initial transient stage,which can easily trigger the inverter current limiting protection and reduce system stability.Therefore,improving the transient performance of hybrid microgrids under sudden increases in active load is the key to ensuring the stable operation of microgrids.This paper first takes the IM and SM parallel system as the research object,and divides the active power output of SM and IM during the transient process of sudden increase in active load into initial active power distribution and dynamic active power transfer.Among them,the initial active power distribution is mainly related to the external equivalent reactance ratio of the microsources,the dynamic active power transfer is mainly related to the difference in angular frequency response between SM and IM.Then,the differences in the external equivalent reactance and angular frequency response of the heterogeneous microsources were analyzed respectively,and the reasons for the excessively high peak active power output of the IM in the initial transient stage were obtained.To quantify the response speed of the parallel system,taking the active load sudden increase as the input and the phase angle difference between SM and IM as the output,the transfer function of the heterogeneous microsources parallel system was constructed,and the influence of the dominant poles’distribution on the response speed was analyzed.Based on the analysis results,a transient active power control strategy for a hybrid island microgrid containing heterogeneous microsources is studied.Without introducing communication,the virtual reactance method is introduced to adjust the initial active power distribution of heterogeneous microsources.At the same time,the dominant pole distribution of the system is changed by adjusting the proportional gain and integral gain of the SM governor to speed up the system response speed.In the case of introducing communication,by introducing the IM additional control strategy,it can suppress IM’s active power output peak value in the initial transient stage and accelerate the system response speed simultaneously,and extend this strategy to the hybrid island microgrid with multiple heterogeneous microsources.Finally,the effectiveness of the analysis conclusion and control strategy of this paper was verified based on Matlab/Simulink time domain simulation.Four calculation examples were constructed:SM and IM parallel system,hybrid island microgrid containing multiple SMs and IMs,heterogeneous microsources island microgrid containing PV,and heterogeneous microsources island microgrid containing PQ-controlled energy storage system.It is verified that the IM additional control strategy can improve the transient performance of the hybrid microgrid in the scenario of a sudden increase in active load.