Abstract: The present application relates to a method for controlling a power system connected to a power grid, including: receiving a reactive power instruction and a measured reactive power from a generator; generating a reactive power error signal based on the difference between the reactive power instruction and the measured reactive power; receiving the reactive power error signal; generating a voltage instruction based on reactive power error signal; generating a voltage droop signal based on a reference reactance and a voltage at a point of common coupling; generating a voltage error signal according to at least one of the voltage instruction or the measured terminal voltage of the generator and the voltage droop signal; and producing a reactive current instruction for the converter power path based on the voltage error signal. The present application also discloses a control system for a power system connected to a power grid and a wind farm.

Abstract: The present application relates to a method for controlling a power system connected to a power grid, including: receiving a reactive power instruction and a measured reactive power from a generator; generating a reactive power error signal based on the difference between the reactive power instruction and the measured reactive power; receiving the reactive power error signal; generating a voltage instruction based on reactive power error signal; generating a voltage droop signal based on a reference reactance and a voltage at a point of common coupling; generating a voltage error signal according to at least one of the voltage instruction or the measured terminal voltage of the generator and the voltage droop signal; and producing a reactive current instruction for the converter power path based on the voltage error signal. The present application also discloses a control system for a power system connected to a power grid and a wind farm.

Abstract: A wind turbine is provided. The wind turbine includes a mechanical system, an electrical system and a controller. The controller is for determining an electrical capability limit of the electrical system according at least in part to one or more operating conditions of the wind turbine and one or more environment conditions of a site of the wind turbine, comparing the electrical capability limit of the electrical system and a mechanical capability limit of the mechanical system, and controlling the electrical system to operate at the smaller one of the electrical capability limit and the mechanical capability limit. A method for controlling a wind turbine comprising a mechanical system and an electrical system is also provided.

Abstract: A wind turbine is provided. The wind turbine includes a mechanical system, an electrical system and a controller. The controller is for determining an electrical capability limit of the electrical system according at least in part to one or more operating conditions of the wind turbine and one or more environment conditions of a site of the wind turbine, comparing the electrical capability limit of the electrical system and a mechanical capability limit of the mechanical system, and controlling the electrical system to operate at the smaller one of the electrical capability limit and the mechanical capability limit. A method for controlling a wind turbine comprising a mechanical system and an electrical system is also provided.

Abstract: A method for reactive power control of a wind farm having a plurality of clusters of wind turbines with a cluster transformer connecting each cluster of wind turbines to a power grid is provided. The method includes receiving, via a plurality of cluster-level controllers, a reactive power command from a farm-level controller. The method also includes generating, via the cluster-level controllers, a cluster-level reactive current command for each cluster of wind turbines based on the reactive power command. Further, the method includes distributing, via the cluster-level controllers, a turbine-level reactive current command to turbine-level controllers of the wind turbines based on the cluster-level reactive current command.

Abstract: A system and method for preventing voltage collapse of a wind turbine power system includes receiving a power input value and a voltage input value from a point of common coupling of the wind turbine power system. The method also includes determining a limit cycle reference point of the wind turbine power system as a function of the input values. The method further includes comparing the limit cycle reference point to at least one predetermined threshold. If the limit cycle reference point is greater than the at least one predetermined threshold, the method includes determining a delta value for the real and reactive voltage commands of the wind turbine power system. Further, the method includes determining updated real and reactive voltage commands based on the delta value. As such, the method also includes operating the wind turbine power system based on the updated real and reactive voltage commands.

Abstract: The present invention discloses a power generation system including a double-fed induction generator, a power converter, and a controller. The double-fed induction generator includes a rotor and a stator coupled to a grid. The power converter includes a rotor side converter coupled to the rotor of the generator, a grid side converter coupled to the grid, and a DC bus coupled between the rotor side converter and the grid side converter. The controller includes a rotor side controller for controlling the rotor side converter and a grid side controller for controlling the grid side converter. The rotor side controller includes a compensator having a transfer function and configured to counter a negative resistance effect of the generator to suppress sub-synchronous oscillations. The present invention further discloses a system for suppressing sub-synchronous oscillations and a method for controlling operation of a power system.

Abstract: The present disclosure provides a wind power generation system, which comprises a wind turbine for generating mechanical energy; a generator for converting the mechanical energy into electrical energy; a converter for converting the electrical energy to expected power for supplying to a grid, wherein a rotor of the generator is connected to converter, an output of a stator of the generator and an output of a converter are both connected to the grid; a controller for controlling the converter to absorb rotor-side reactive power Qrotor and to increase line-side reactive power Qline, so as to meet a reactive power demand of the grid, when a rotor speed is less than a predetermined value.

Abstract: A method for reactive power control of a wind farm having a plurality of clusters of wind turbines with a cluster transformer connecting each cluster of wind turbines to a power grid is provided. The method includes receiving, via a plurality of cluster-level controllers, a reactive power command from a farm-level controller. The method also includes generating, via the cluster-level controllers, a cluster-level reactive current command for each cluster of wind turbines based on the reactive power command. Further, the method includes distributing, via the cluster-level controllers, a turbine-level reactive current command to turbine-level controllers of the wind turbines based on the cluster-level reactive current command.

Abstract: The present application relates to a method for controlling a power system connected to a power grid, including: receiving a reactive power instruction and a measured reactive power from a generator; generating a reactive power error signal based on the difference between the reactive power instruction and the measured reactive power; receiving the reactive power error signal; generating a voltage instruction based on reactive power error signal; generating a voltage droop signal based on a reference reactance and a voltage at a point of common coupling; generating a voltage error signal according to at least one of the voltage instruction or the measured terminal voltage of the generator and the voltage droop signal; and producing a reactive current instruction for the converter power path based on the voltage error signal. The present application also discloses a control system for a power system connected to a power grid and a wind farm.

Abstract: It is a system for supplying power to at least one load. The system comprises at least one power source, load bank and control device coupled to the at least one load. The load bank is coupled to at least one power source and at least one load. The load bank comprises a controllable voltage source, at least three resistors coupled between an output side of the controllable voltage source and the at least one power source, and at least one storage element. The controllable voltage source comprises more than one switches. And the at least one storage element comprises one or more capacitors, batteries, or combinations thereof. The control device is configured for controlling the switches during a first condition such that, to the extent that an output power of the at least one power source exceeds a requisite power of the at least one load, any excess output power is either supplied to the at least one storage element or consumed by the at least three resistors.

Abstract: The present disclosure provides a wind power generation system, which comprises a wind turbine for generating mechanical energy; a generator for converting the mechanical energy into electrical energy; a converter for converting the electrical energy to expected power for supplying to a grid, wherein a rotor of the generator is connected to converter, an output of a stator of the generator and an output of a converter are both connected to the grid; a controller for controlling the converter to absorb rotor-side reactive power Qrotor and to increase line-side reactive power Qline, so as to meet a reactive power demand of the grid, when a rotor speed is less than a predetermined value.

Abstract: A wind generation system includes a wind turbine for generating mechanical power, a doubly-fed induction generator for converting the mechanical power to electrical power, a converter for converting the electrical power to a desired electrical power for supplying to a power grid, and a transformer through which a stator of the generator is coupled to the power grid. When a measured rotation speed feedback from the rotor of the generator is lower than an original cut-in rotation speed of the rotor, a cut-in rotation speed of the rotor is lowered by determining a DC link voltage margin of the converter, determining a DC link voltage setpoint of the converter based on the determined DC link voltage margin; and controlling the converter based on the determined DC link voltage setpoint; and/or by increasing a turn ratio of the transformer to reduce a grid voltage from the power grid.

Abstract: The present invention discloses a power generation system including a double-fed induction generator, a power converter, and a controller. The double-fed induction generator includes a rotor and a stator coupled to a grid. The power converter includes a rotor side converter coupled to the rotor of the generator, a grid side converter coupled to the grid, and a DC bus coupled between the rotor side converter and the grid side converter. The controller includes a rotor side controller for controlling the rotor side converter and a grid side controller for controlling the grid side converter. The rotor side controller includes a compensator having a transfer function and configured to counter a negative resistance effect of the generator to suppress sub-synchronous oscillations. The present invention further discloses a system for suppressing sub-synchronous oscillations and a method for controlling operation of a power system.

Abstract: A system and method for preventing voltage collapse of a wind turbine power system includes receiving a power input value and a voltage input value from a point of common coupling of the wind turbine power system. The method also includes determining a limit cycle reference point of the wind turbine power system as a function of the input values. The method further includes comparing the limit cycle reference point to at least one predetermined threshold. If the limit cycle reference point is greater than the at least one predetermined threshold, the method includes determining a delta value for the real and reactive voltage commands of the wind turbine power system. Further, the method includes determining updated real and reactive voltage commands based on the delta value. As such, the method also includes operating the wind turbine power system based on the updated real and reactive voltage commands.

Abstract: A wind generation system includes a wind turbine for generating mechanical power, a doubly-fed induction generator for converting the mechanical power to electrical power, a converter for converting the electrical power to a desired electrical power for supplying to a power grid, and a transformer through which a stator of the generator is coupled to the power grid. When a measured rotation speed feedback from the rotor of the generator is lower than an original cut-in rotation speed of the rotor, a cut-in rotation speed of the rotor is lowered by determining a DC link voltage margin of the converter, determining a DC link voltage setpoint of the converter based on the determined DC link voltage margin; and controlling the converter based on the determined DC link voltage setpoint; and/or by increasing a turn ratio of the transformer to reduce a grid voltage from the power grid.

Abstract: A system includes a source side converter for being electrically coupled to a generator of a power source, a line side converter for being electrically coupled to a power network, a DC link coupled between the source side converter and the line side converter, and a controller for generating source side switching signals based on a current or torque of the generator and a virtual impedance signal for system damping or reactive power compensation when at least one detected signal of the system is not normal. A method for controlling the system is also included.

Abstract: It is a system for supplying power to at least one load. The system comprises at least one power source, load bank and control device coupled to the at least one load. The load bank is coupled to at least one power source and at least one load. The load bank comprises a controllable voltage source, at least three resistors coupled between an output side of the controllable voltage source and the at least one power source, and at least one storage element. The controllable voltage source comprises more than one switches. And the at least one storage element comprises one or more capacitors, batteries, or combinations thereof. The control device is configured for controlling the switches during a first condition such that, to the extent that an output power of the at least one power source exceeds a requisite power of the at least one load, any excess output power is either supplied to the at least one storage element or consumed by the at least three resistors.

Abstract: A system includes a source side converter for being electrically coupled to a generator of a power source, a line side converter for being electrically coupled to a power network, a DC link coupled between the source side converter and the line side converter, and a controller for generating source side switching signals based on a current or torque of the generator and a virtual impedance signal for system damping or reactive power compensation when at least one detected signal of the system is not normal. A method for controlling the system is also included.

Abstract: A system for power conversion includes a power converter having switching elements, a detector, and a controller is provided. The detector detects a parameter and provides electrical signals indicative of the parameter. The controller receives the electrical signals transmitted from the detector, and sends commands to instruct the power converter to perform power conversion by operating the switching elements in accordance with switching signals at a different frequency in response to a detection of the system condition. A method for operating the system is also provided.