Open AccessNovel power flow analysis method based on impedance matching for UPQC with grid voltage fluctuations and unbalanced loads
Author(s) -
Zhao Xiaojun,
Zhang Chunjiang,
Guo Xiaoqiang,
Chai Xiuhui,
Jia Dongqiang,
Shi Changli,
Wei Tongzhen
Publication year - 2020
Publication title -
iet power electronics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.637
H-Index - 77
eISSN - 1755-4543
pISSN - 1755-4535
DOI - 10.1049/iet-pel.2019.1447
Subject(s) - impedance matching , electrical impedance , control theory (sociology) , rectifier (neural networks) , voltage , input impedance , electronic engineering , node (physics) , equivalent impedance transforms , engineering , electrical engineering , computer science , stochastic neural network , control (management) , structural engineering , artificial intelligence , machine learning , recurrent neural network , artificial neural network
A new perspective of impedance matching is proposed to study the power flow operation of the three‐phase four‐wire (3P4W) unified power quality conditioner (UPQC) system. Specifically, the UPQC system is equivalent to an adjustable impedance network, when external conditions change, such as grid voltage sag/swell and unbalanced loads, the node impedances in the network will be dynamically matched. On the one hand, the three nodes of the series converter (SC) will be matched as positive or negative impedances with the change of grid voltages, which means that the SC operates in a rectifier or inverter state to absorb or transmit the energy. On the other hand, to compensate the unbalanced load currents, the three nodes of the parallel converter (PC) will be matched as positive and negative impedances at the same time, which means that the PC operates in both rectifier and inverter state to absorb and transmit the energy. After matching the node impedances, the system's output node impedances are equal to the load impedances, thus achieving the power balance of the whole system. Experimental results of the power flow and impedance matching from a laboratory‐scale prototype hardware are presented to evaluate the correctness of the impedance analysis.