Variable-Slope Droop Control Strategy Based on Power Flow Distribution of Multiterminal DC Grid

doi:10.3969/j.issn.1000－7229.2017.03.003

Abstract

Abstract: Flexible direct current transmission system (FACTS) is an effective technique for large scale renewable energy integration. As the main coordinated control between stations in multi-terminal high voltage direct current transmission (MTDC) system, droop control has some disadvantages such as low utilization rate of DC power, poor quality of DC voltage and causing over-voltage easily. To improve the control performance of droop control, firstly, this paper derives the general power flow calculation method for DC grid, which is applicable for any control combination of DC grid in convertor station. Then, this paper proposes an improved droop control strategy based on power flow calculation. According to different needs, the strategy consists of 3 control modes recalculating droop coefficient. Finally, a 4-terminal DC network is developed in PSCAD/EMTDC and time-domain simulation is performed. The results show that the proposed variable-slope droop control strategy can effectively reduce the steady-state error and prevent overvoltage.

Key words: VSC-MTDC, modular multilevel converter (MMC), power flow, droop control

CLC Number:

TM 72

MIAO Dan, LIU Tianqi, WANG Shunliang. Variable-Slope Droop Control Strategy Based on Power Flow Distribution of Multiterminal DC Grid[J]. Electric Power Construction, 2017, 38(3): 19-.

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