Method for controlling a wind power plant and a wind power plant

A wind power plant comprising a plant controller, the plant controller comprising:

• a grid voltage sensor at a point of coupling to a power grid for a wind power plant, configured to detect a deviation in grid voltage for the wind power plant from a defined operation range, the deviation indicating a grid fault;
• and
• a state controller for the wind power plant configured to change a wind power plant operational state from a normal operation state to a fault ride through state upon indication of a grid fault, and to a fault recovery state for the wind power plant when the grid voltage returns to within the normal operation range;
• the wind power plant further comprising:
• a plurality of wind turbine generators, each of the plurality of wind turbine generators comprising:
• a wind turbine power controller, in communication with the plant controller, and configured to operate each of the plurality of wind turbine generators to carry out an independent fault recovery process at the direction of the plant controller through each of the plurality of wind turbine generators during the fault recovery state, the wind turbine power controller comprising:
• a turbine voltage sensor configured, for the respective wind turbine generator, to determine through measurement a voltage measurement that is reflective of the grid voltage for the wind power plant grid;
• a predetermined reference grid voltage that is provided at each wind turbine power controller and that is reflective of a target voltage level for the wind power plant grid;
• a summation module configured to compare the measured voltage measurement that is reflective of grid voltage for the wind power plant grid to the predetermined reference grid voltage to obtain a difference value;
• and
• a voltage control current reference module configured to use a proportional-integral or a proportional-integral-derivative controller to determine a variable current reference based on to the difference value for each individual wind turbine generator of the plurality of wind turbine generators to generate a varying reactive current from that wind turbine generator to contribute to the grid coupled with the wind power plant for regulating the grid voltage to achieve the predetermined reference grid voltage.