1. School of Electrical Engineering Beijing Jiaotong University Beijing 100044 China; 2. Beijing Engineering Research Center of Electric Rail Transportation Beijing 100044 China; 3. Chinese Society for Electrical Engineering Beijing 100761 China
Abstract: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.
赵郅毅, 许寅, 吴翔宇, 董江浩. 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[J]. 电工技术学报, 2024, 39(19): 6072-6084.
Zhao Zhiyi, Xu Yin, Wu Xiangyu, Dong Jianghao. Transient Active Power Response Analysis and Control Strategy of Hybrid Island Microgrid Containing Heterogeneous Microsources. Transactions of China Electrotechnical Society, 2024, 39(19): 6072-6084.
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