Research on Reactive Power Compensation Method of Long-Distance and Large-Capacity Offshore Wind Farm High Voltage AC Transmission System

The overvoltage and reactive power imbalance issues brought on by the large charging reactive power of transmission submarine cables are becoming more and more noticeable as the offshore wind farm alternating current (AC) transmission system moves toward long distance, high voltage, and large capacity. This paper presents a reactive power compensation approach that takes into account the system’s steady-state reactive power requirements as well as power frequency overvoltage with the goal to increase the safety and reliability of system operation. Firstly, the offshore wind power high-voltage AC transmission system simulation model is built in PSCAD/EMTDC. Secondly, in order to configure the capability of the fixed high-voltage shunt reactors placed in the onshore control center, different kinds of power frequency overvoltage are investigated and compared. Then, the steady-state reactive power demands are analyzed, the compensation capacity and switching stages of the adjustable shunt reactor are determined with the goal of no reactive power flow at the point of common coupling (PCC), and a reasonable control strategy is formulated. Finally, the simulation verification shows that the reactive power compensation method can limit power frequency overvoltage to the specified range and compensate the steady-state reactive power demand in real time.