Inter-pole Cooperative Control Strategy for True Bipolar MMC-HVDC System with Offshore Wind Power

Abstract

Abstract For offshore wind power via a true bipolar MMC-HVDC delivery system, when both poles of the offshore converter stations adopt fixed AC voltage and fixed frequency control (referred to as fixed V/f control), the converter stations are connected to the same bus and control the same target, resulting in unstable operation of the system. Therefore, this paper proposes an inter-pole cooperative control strategy for a true bipolar MMC-HVDC system with offshore wind power. One pole of the offshore converter station adopts fixed V/f control to supply stable AC voltage to the offshore AC system, and the other pole adopts inter-pole cooperative control to achieve balanced power distribution between the two poles, thus improving the system power transmission margin and reducing power losses. Finally, a simulation project is established on the PSCAD/EMTDC to confirm the usefulness of the inter-pole cooperative control strategy.