Research on Unbalance Fault-Tolerant Control Strategy of Modular Multilevel Photovoltaic Grid-Connected Inverter

Yiqi Liu, Danhua Li, Yu Jin, Qingbo Wang and Wenlong Song
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Yiqi Liu: College of Mechanical and Electrical Engineering, Northeast Forestry University, Harbin 150040, China
Danhua Li: Maintenance Branch Company, State Grid Chongqing Electric Power Company, Chongqing 400039, China
Yu Jin: School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin 150001, China
Qingbo Wang: College of Mechanical and Electrical Engineering, Northeast Forestry University, Harbin 150040, China
Wenlong Song: College of Mechanical and Electrical Engineering, Northeast Forestry University, Harbin 150040, China

Energies, 2018, vol. 11, issue 6, 1-18

Abstract: The average switching model of modular multilevel converter (MMC) is built in this paper when the hot reserved strategy is adopted as a fault-tolerant control. When the MMC SM faults, the rest of the SMs cannot support the DC-link voltage, which results in interruption of the inverter. To tackle this issue, a novel fault-tolerant control strategy is proposed to bypass the SM under fault and re-regulate the SM capacitor voltage and carrier phase-shift angle to maintain the main components of circulating current, and reduce the Total Harmonic Distortion (THD) of grid connected current to enable the stable operation of the photovoltaic inverter. The maximum power tracking control is improved to solve the problem of long restoration time when faults occur, based on a constant voltage startup method combined with a fix-step incremental conductance method. Simulations in MATLAB/Simulink and experimental results have verified the feasibility and effectiveness of the proposed control strategy.

Keywords: PV grid-connected; modular multilevel converter (MMC); fault-tolerant control; circulating current; maximum power point tracking (MPPT) (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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