Multimode Operation Mechanism Analysis and Power Flow Flexible Control of a New Type of Electric Energy Router for Low-Voltage Distribution Network
Xiaojun Zhao, Yingrui Liu, Xiuhui Chai, Xiaoqiang Guo, Xiaohuan Wang, Chunjiang Zhang, Tongzhen Wei, Changli Shi, Dongqiang Jia
Abstract
Due to limitations of topology, the series architecture electric energy router (SA-EER) for low-voltage distribution network (LVDN) has the disadvantages that the energy transmission range is limited to 100% and reactive powers are unable to operate flexibly. For this reason, a new type of EER with series-parallel architecture (SPA-EER) is constructed in this paper, and it can break through the above disadvantages in SA-EER. In addition to series-parallel architecture, a two-degree-of-freedom power flow flexible control strategy (TDF-PFFCS) is proposed to further support the realization of these two breakthroughs. According to TDF, the operation states of SPA-EER can be discriminated into 6 modes, and then their operation mechanisms are analyzed. Considering the rated capacity limitations of LVDN ports and power electronic converters in SPA-EER, the operation ranges of TDF are discussed, and constraint relationships between TDF and these rated capacities are further established, so as to avoid the issue of over-limit rated capacities. Finally, the simulation results prove that the constructed SPA-EER and proposed TDF-PFFCS can achieve the transmission targets that the maximum allowable amounts of active and reactive powers are 200% and 120% respectively, which provides new design ideas and solutions for EERs to realize the high-power energy flexible transmission.