Wind power generating equipment includes: a generator that is driven by a blade which rotates by receiving the wind; a power converter that converts an electric output of the generator such that the output is interconnected with an electric power system; a power converter controller that controls the power converter; and a wind turbine control board that transmits, to the power converter controller, an active power command value that is used as a command value of the electric output which is transmitted from the power converter. The power converter controller controls the output of the power converter in response to an active power command value, depending on a reduction amount of a system voltage when instantaneous reduction occurs in the system voltage interconnected with the wind power generating equipment. This permits stable operation of the wind power generating system when instantaneous voltage reduction occurs such as during a system abnormality.

An electric power converter includes an electric gatedriver circuit that includes a transformer. The transformer includes separate first and second cores of magnetically conductive material that are shaped to form respective closed loops. The transformer also includes a first electrical conductor with at least one winding arranged around a part of the first core in a first winding direction and at least one winding arranged around a part of the second core in a second winding direction opposite the first winding direction. The transformer further includes a second electrical conductor with at least one winding arranged around a part of the first core in the first winding direction and at least one winding arranged around a part of the second core in the second winding direction so as to counteract electric influence induced by a common magnetic field through the closed loops of the first and second cores.

Aspects of the present invention relate to a method for controlling a renewable power plant connected to a power network to reduce deviation of a measured frequency of the power network from a target frequency. The method comprises determining a forecasted power gradient over a forecast interval defined between a first time point and a second time point, and, at a third time point during the forecast interval, controlling the power plant to output active power according to a minimum active power level if the measured frequency at the third time point is below the target frequency, controlling the power plant to output active power according to a maximum active power level if the measured frequency at the third time point is above the target frequency. The maximum and minimum active power levels are based on the forecasted power gradient.

A method for connecting a power transformer, located between an inverter of a wind turbine and an electrical grid, to the electrical grid; the method comprises the steps gradually increasing a voltage at a primary side of the transformer from a low starting voltage to a target voltage equal or close to a nominal voltage of the transformer, by means of the inverter of the wind turbine or by means of an auxiliary inverter, thereby increasing the voltage at a secondary side of the transformer, wherein the gradually increasing of the voltage uses energy of an internal energy storage device, connecting the secondary side of the transformer to the electrical grid after predefined target conditions have been reached.

Provided is a control circuit of a converter, in particular a power converter of a wind power installation, configured to control the converter in such a way that the converter emulates a behavior of a synchronous machine. The control circuit includes a power module for calculating a power change depending on a detected power and a correction module for setting a power set point, in particular for the converter, depending on the calculated power change.

Provided is a method of feeding electric reactive power using a wind farm comprising wind turbines. The wind farm feeds a wind farm active power output and the wind farm active power output includes individual plant active power outputs each generated by one of the wind turbines. The wind farm feeds a wind farm reactive power output into the electrical supply network and the wind farm reactive power output includes individual plant reactive power outputs each generated by one of the wind turbines. The method includes determining a total wind farm reactive power output to be fed in by the wind farm and calculating, for each wind turbine, an individual plant reactive power output to be generated. The individual plant reactive power output is determined depending on the individual plant active power output and depending on the wind farm reactive power output to be fed in.

The present application provides a method and a system for controlling continuous low voltage ride-through and high voltage ride-through of a permanent magnet direct-driven wind turbine. The method includes: determining a transient time period during which the wind turbine is transitioned from a low voltage ride-through state to a high voltage ride-through state; controlling the wind turbine to provide, during the transient time period, a gradually increasing active current to the point of common coupling; and controlling the wind turbine to provide, during the transient time period, a reactive current to the point of common coupling according to an operation state of the wind turbine before the low voltage ride-through state.

A method for mitigating voltage disturbances at a point of interconnection (POI) of a grid-forming inverter-based resource (IBR) due to flicker includes receiving a voltage reference command and a voltage feedback. The voltage feedback contains information indicative of the voltage disturbances at the POI due to the flicker. The method also includes determining a power reference signal for the IBR based on the voltage reference command and the voltage feedback. Moreover, the method includes generating a current vector reference signal based on the power reference signal, the current vector reference signal containing a frequency component of the voltage disturbances. Further, the method includes generating a transfer function of a regulator based on the frequency component to account for the flicker effect. In addition, the method includes generating a current vector based on a comparison of the current vector reference signal and a current vector feedback signal. Thus, the method includes regulating a voltage vector command using the current vector to mitigate the voltage disturbances.

A method of transmitting reactive power between at least one wind turbine and a power system through a transformer connected between the at least one wind turbine and the power system, the wind turbine including a power converter. The method includes a second step of connecting at least one passive device to the transformer and reducing or increasing a reactive power of the power converter of an amount corresponding to the reactive contribution from the passive device.

A grid-forming wind turbine control method for a diode rectifier unit-based offshore wind power transmission system. A control system for controlling a grid-side converter has a three-layered structure, where a first layer is a combination of an active power controller and a reactive power controller; a second layer is a voltage controller; and a third layer is a current controller. The actual reactive power is represented by a per-unit value of a capacity of a corresponding wind turbine unit. The wind turbine units have the same reactive-power reference value, which is constant and does not change with time. The reactive power controllers of all wind turbine units have the same structure and parameters.