A Circulating Current Interline DC Power Flow Controller for DC Grid
Li Guoqing, Bian Jing, Wang He, Wang Zhenhao
Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin 132000 China
Abstract Aiming at the problem of insufficient free degree of power flow control in DC grid, this paper proposes a novel interline DC power flow controller (I-PFC). I-PFC can realize the power balance through the AC circulating current without AC transformer as AC internal pathway. Compared with the existing interline DC power flow controller, it further reduces the current fluctuation caused by charging and discharging of a single capacitor, and has the advantages of avoiding additional resonance, reducing harmonics and expanding easily. Firstly, the topology of I-PFC was proposed, and the method of power flow control was analyzed. Then the relationship between line current and series voltage was obtained, and the principle of power balance using internal AC circulating current was introduced. Secondly, according to the power and energy of I-PFC, the capacitor voltage of sub-module was analyzed in detail. It mainly consisted of DC, fundamental frequency and two frequency doubling components. The control strategy including DC power flow control and power balance control was designed. Finally, a three-terminal ring VSC-HVDC including I-PFC was built in PSCAD/EMTDC. The feasibility and effectiveness of the proposed I-PFC were verified by input operation, reverse regulation and dynamic response.
Li Guoqing,Bian Jing,Wang He等. A Circulating Current Interline DC Power Flow Controller for DC Grid[J]. Transactions of China Electrotechnical Society, 2020, 35(5): 1118-1127.
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2020, Vol. 35 
