Determining reactive power capability of a renewable energy system

A control system for controlling a renewable energy system, the control system comprising:

• a voltage regulator implemented by one or more control devices, the voltage regulator configured to provide a reactive power command based at least in part on a voltage error signal;
• a limiter implemented by the one or more control devices, the limiter configured to limit the reactive power command based at least in part on an initial reactive power limit for the renewable energy system;
• a reactive power limit correction module implemented by the one or more control devices, the reactive power limit correction module configured to adjust the initial reactive power limit to a corrected reactive power limit when a difference between the reactive power command for the renewable energy system and an actual reactive power production for the renewable energy system falls outside of a threshold, and wherein the reactive power limit correction module is configured to detect the difference returning to within the threshold, and in response to detecting the difference returning to within the threshold, control the reactive power output based at least in part on the initial reactive power limit;
• wherein the corrected reactive power limit corrects the initial reactive power limit towards the actual reactive power capability of the renewable energy system.

A wind farm, comprising:

• a plurality of wind turbines;
• a plurality of wind turbine controllers, each wind turbine controller associated with at least one of the plurality of wind turbines;
• and
• a wind farm controller, the wind farm controller in communication with each of the wind turbine controllers, the wind farm controller configured to adjust an initial reactive power limit to a corrected reactive power limit based at least in part on a difference between a reactive power demand for the wind farm and an actual reactive power production for the wind farm, the wind farm controller further configured to control the reactive power output for the wind farm based on the corrected reactive power limit, and wherein the wind farm controller is configured to detect the difference returning to within a threshold, and in response to detecting the difference returning to within the threshold, control the reactive power output based at least in part on the initial reactive power limit;
• wherein the initial reactive power limit is determined by aggregating a rated reactive power for each of a plurality of wind turbines in the wind farm and the corrected reactive power limit adjusts the initial reactive power limit toward an actual reactive power capability of the wind farm.