Optimization of reactive power in high-voltage AC transmission systems for long-distance offshore wind power using high-voltage shunt adjustable reactor

High-voltage shunt reactor (HVSR) is essential for the high-voltage AC transmission system of long-distance offshore wind power to achieve in-situ reactive power balancing and to limit industrial frequency overvoltage. However, the use of fixed-capacity HVSR further reduces the power factor at the shunt point when the wind farm produces higher output power. Therefore, a method for reactive power allocation and optimal control, based on high-voltage shunt adjustable reactor (HVSAR), is proposed for the high-voltage AC transmission system of long-distance offshore wind power. First, the numerical relationship between reactive power and voltage in the offshore wind power transmission system via cable is calculated. The mechanism of HV AC cable capacitive overvoltage generation is analyzed to derive the need for inductive reactive power compensation at the grid connection point. Then, an optimal reactive power allocation method for the offshore wind power AC transmission system is proposed. This method combines the reactive power compensation allocation principle with the results of dynamic and static system analyses. Additionally, a control strategy for the HVSAR is developed based on these principles. Finally, using the PSCAD/EMTDC (Power Systems Computer Aided Design) simulation platform, a model of an actual offshore wind farm connected to the AC receiving system is created. The optimal reactive power allocation method and control strategy for the HVSAR are then simulated and verified under various operating conditions. The simulation results demonstrate the feasibility and accuracy of the proposed configuration and control strategy.