Two-stage Reactive Power and Voltage Coordinated Control Strategy for Photovoltaic Power Station Considering Multiple Reactive Power Sources

Considering the regulating performance of multiple reactive power sources, a reactive power and voltage coordinated control strategy which comprehensively utilizes the static var generator (SVG), photovoltaic inverters and capacitors is presented, with two control stages involved. The first stage is coordinated voltage control considering multiple reactive power sources, which maximizes the use of reactive power sources, so as to reduce switching frequency of capacitors, and quickly responds to the change in system reactive power, while maintaining voltage stability at the point of common coupling. The second stage consists in dynamic reactive power optimization control, through the replacement of dynamic reactive power (SVG) with static reactive power (capacitors), and fast reactive power (SVG) with slow reactive power (photovoltaic inverters). The SVG retains sufficient reactive margin, to make the power grid more capable of surmounting the problem of voltage collapse. Finally, the reactive power and voltage control strategy is applied in actual photovoltaic power stations to verify the strategy. © 2017 Automation of Electric Power Systems Press.