Abstract: A method for operating a wind turbine generator connected to a power network to account for recurring voltage faults on the power network caused by automatic reclosure of at least one circuit breaker following a short-circuit. The method comprises: identifying a deviation of voltage level of the power network from a normal operational voltage level of the network; determining that the identified deviation fulfils criteria for automatic reclosure; and operating the wind turbine generator in a recurring fault mode if automatic reclosure criteria are fulfilled. When operating the wind turbine generator in recurring fault mode, the method comprises: monitoring the recovery of the voltage level from the deviation; categorising the recovery of the voltage as one of at least a strong recovery or a weak recovery; and implementing a ride-through protocol according to the category of recovery.

Abstract: There is provided a method of operating a renewable power plant that is connected to a wider power network by a bus. The method comprises: identifying a predetermined voltage condition of the renewable power plant or of the bus; controlling the renewable power plant to maintain zero reactive power exchange at the bus for a first period; calculating an average voltage level of the bus that was achieved during the first period; and controlling the renewable power plant to maintain the voltage output at a set voltage level for a second period, the set voltage level being substantially equal to the calculated average voltage level. The method ensures that voltage oscillations due to a push-pull phenomenon between a power plant controller and the power network do not upset the stability of the grid.

Abstract: A method of controlling a hybrid power plant connected to a power network, the hybrid power plant having a first renewable energy generator and a second renewable energy generator, the first renewable energy generator being configured to generate power using a different source of renewable energy to the second renewable energy generator. The method comprises: determining a target plant power output for the hybrid power plant; determining a target generator power output for each of the first and second generators based on the target plant power output; determining a respective ramp rate for each of the first and second renewable energy generators based, at least in part, on an attribute of the respective renewable energy generator; and operating each of the first and second renewable energy generators to change its power output to the power network at the determined ramp rate to achieve the target generator power output.

Abstract: A method for controlling a renewable energy power plant comprising a plurality of renewable energy generators, the method comprising: carrying out the following steps dynamically: determining a reactive power capability value of the power plant based on the generated active power of each of the renewable energy generators within the power plant; determining a reactive power exchange limit value based on a measured grid voltage level; and controlling the power plant so that the generated reactive power does not exceed the lower of the determined reactive power capability value and the determined reactive power exchange limit value that are determined dynamically.

Abstract: There is provided a method for operating a renewable energy power plant comprising a plurality of renewable energy generators, the method comprising: calculating a rate of change of reactive power reference level for transitioning between a present reactive power reference level, output by a reactive power controller, and a target reactive power reference level, the target reference level being suitable for normal operation of the renewable energy power plant; and, following a fault on a power network to which the renewable energy power plant is connected, dispatching a control signal for controlling the renewable energy power plant to generate or consume reactive power at the calculated rate of change to transition the reactive power level of the renewable energy power plant to the target reactive power reference level.

Abstract: Operating a renewable energy generator forming part of a renewable energy power plant. During a fault experienced by a power network: determining an active current set point to enable a reactive current supply boost at the point of connection between the plant and the network, the active current set point being based on a voltage level associated with the generator and on operational characteristics of the generator, plant, power network and/or connecting network; calculating a time period for the reactive current boost, the time period being the maximum time that the active current set point can be maintained for; and controlling the generator during the calculated time period to alter active current output to the determined active current set point, thereby providing the reactive current supply boost at the point of connection.

Abstract: A control system for controlling the power output of a plurality of renewable energy generators, a power network connecting those generators to a Point of Interconnection (PoI) with which the power network is connected to an external power grid, and measurement means configured to measure electrical parameters associated with the Point of Interconnection, wherein the control system is configured to: operate each renewable energy generator to achieve a respective current level at a terminal of the generator that is equal to a current set point; implement, during a grid fault event, a feedback control routine in which the control system: determines a measured value of an electrical parameter at the Point of Interconnection, determines a target value of the electrical parameter; and modifies the current set point based on the measured value and the target value of the electrical parameter.

Abstract: A method for controlling a renewable energy power plant comprising a plurality of renewable energy generators, the method comprising: carrying out the following steps dynamically: determining a reactive power capability value of the power plant based on the generated active power of each of the renewable energy generators within the power plant; determining a reactive power exchange limit value based on a measured grid voltage level; and controlling the power plant so that the generated reactive power does not exceed the lower of the determined reactive power capability value and the determined reactive power exchange limit value that are determined dynamically.

Abstract: A method of controlling a hybrid power plant connected to a power network, the hybrid power plant having a first renewable energy generator and a second renewable energy generator, the first renewable energy generator being configured to generate power using a different source of renewable energy to the second renewable energy generator. The method comprises: determining a target plant power output for the hybrid power plant; determining a target generator power output for each of the first and second generators based on the target plant power output; determining a respective ramp rate for each of the first and second renewable energy generators based, at least in part, on an attribute of the respective renewable energy generator; and operating each of the first and second renewable energy generators to change its power output to the power network at the determined ramp rate to achieve the target generator power output.

Abstract: A wind power plant system comprising: a plurality of wind turbine generators each having a corresponding generator controller, and a power plant controller for controlling the power generated by the wind power plant system; wherein at least some of the plurality of generator controllers are each configured to: generate a model that indicates the thermal capacity of one or more components of the wind turbine generator, determine power capacity data from the model, said data relating to: at least one reactive power supply level and a corresponding time limit for which that reactive power supply level may be maintained, and transmit to the power plant controller the determined power capacity data, wherein the power plant controller is operable to receive the power capacity data from the plurality of generator controllers and to transmit respective power references to the plurality of generator controllers to control the power generated by the wind power plant system.

Abstract: There is provided a method of operating a renewable power plant that is connected to a wider power network by a bus. The method comprises: identifying a predetermined voltage condition of the renewable power plant or of the bus; controlling the renewable power plant to maintain zero reactive power exchange at the bus for a first period; calculating an average voltage level of the bus that was achieved during the first period; and controlling the renewable power plant to maintain the voltage output at a set voltage level for a second period, the set voltage level being substantially equal to the calculated average voltage level. The method ensures that voltage oscillations due to a push-pull phenomenon between a power plant controller and the power network do not upset the stability of the grid.

Abstract: A method for operating a renewable energy power plant comprising a plurality of renewable energy generators. The method comprises: identifying a predetermined condition of the renewable energy power plant, of the grid, or of the connection between the renewable energy power plant and the grid, the predetermined condition indicating a weak grid interconnection between the renewable energy power plant and the grid; and controlling each renewable energy generator in an adaptive active power mode in response to recovery of the grid from a voltage deviation. The adaptive active power mode comprises: determining a thermal capacity of a chopper resistor of the renewable energy generator; calculating, based upon the determined thermal capacity, a limit level of rate of change of active power output that may be implemented by the renewable energy generator; and operating the renewable energy generator to output active power at the calculated rate of change limit level.

Abstract: A method for operating a wind turbine generator connected to a power network to account for recurring voltage faults on the power network caused by automatic reclosure of at least one circuit breaker following a short-circuit. The method comprises: identifying a deviation of voltage level of the power network from a normal operational voltage level of the network; determining that the identified deviation fulfils criteria for automatic reclosure; and operating the wind turbine generator in a recurring fault mode if automatic reclosure criteria are fulfilled. When operating the wind turbine generator in recurring fault mode, the method comprises: monitoring the recovery of the voltage level from the deviation; categorising the recovery of the voltage as one of at least a strong recovery or a weak recovery; and implementing a ride-through protocol according to the category of recovery.

Abstract: A method for operating a renewable energy power plant comprising a plurality of renewable energy generators. The method comprises: identifying a predetermined condition of the renewable energy power plant, of the grid, or of the connection between the renewable energy power plant and the grid, the predetermined condition indicating a weak grid interconnection between the renewable energy power plant and the grid; and controlling each renewable energy generator in an adaptive active power mode in response to recovery of the grid from a voltage deviation. The adaptive active power mode comprises: determining a thermal capacity of a chopper resistor of the renewable energy generator; calculating, based upon the determined thermal capacity, a limit level of rate of change of active power output that may be implemented by the renewable energy generator; and operating the renewable energy generator to output active power at the calculated rate of change limit level.

Abstract: A method for controlling a renewable energy power plant comprising a plurality of wind turbine generators, the method comprising: measuring a voltage level associated with a point of interconnection between a power transmission network and the power plant; calculating a reactive power exchange limit based upon the measured voltage level; and controlling the power plant so that the calculated reactive power exchange limit is not exceeded.

Abstract: A control system for controlling the power output of a plurality of renewable energy generators, a power network connecting those generators to a Point of Interconnection (PoI) with which the power network is connected to an external power grid, and measurement means configured to measure electrical parameters associated with the Point of Interconnection, wherein the control system is configured to: operate each renewable energy generator to achieve a respective current level at a terminal of the generator that is equal to a current set point; implement, during a grid fault event, a feedback control routine in which the control system: determines a measured value of an electrical parameter at the Point of Interconnection, determines a target value of the electrical parameter; and modifies the current set point based on the measured value and the target value of the electrical parameter.

Abstract: A wind power plant system comprising: a plurality of wind turbine generators each having a corresponding generator controller, and a power plant controller for controlling the power generated by the wind power plant system; wherein at least some of the plurality of generator controllers are each configured to: generate a model that indicates the thermal capacity of one or more components of the wind turbine generator, determine power capacity data from the model, said data relating to: at least one reactive power supply level and a corresponding time limit for which that reactive power supply level may be maintained, and transmit to the power plant controller the determined power capacity data, wherein the power plant controller is operable to receive the power capacity data from the plurality of generator controllers and to transmit respective power references to the plurality of generator controllers to control the power generated by the wind power plant system.