Abstract: A power generation system (100, 200, 300, 400) is presented. The power generation system includes a prime mover (102), a doubly-fed induction generator (DFIG) (104) having a rotor winding (126) and a stator winding (122), a rotor-side converter (106), a line-side converter (108), and a secondary power source (110, 401) electrically coupled to a DC-link (128). Additionally, the power generation system includes a control sub-system (112, 212, 312) having a controller, and a plurality of switching elements (130, and 132 or 201). The controller is configured to selectively control switching of one or more switching elements (130, and 132 or 201) based on a value of an operating parameter corresponding to at least one of the prime mover, the DFIG, or the secondary power source to connect the rotor-side converter in parallel to the line-side converter to increase an electrical power production by the power generation system.

Abstract: A method for optimizing reactive power generation of an electrical power system includes generating, via a plurality of cluster-level controllers, a cluster-level reactive power command for each cluster of electrical power subsystems based on a system-level reactive power command. The method also includes determining, via the cluster-level controllers, a subsystem-level reactive power command for each of the electrical power subsystems based on the cluster-level reactive power command. Further, the method includes evaluating, via a plurality of subsystem-level controllers, reactive power capability of a plurality of reactive power sources within each of the electrical power subsystems. Moreover, the method includes generating, via each of the subsystem-level controllers, an actual reactive power for each of the electrical power subsystems based on the evaluation by allocating a portion of the subsystem-level reactive power command to each of the plurality of reactive power sources.

Abstract: A method is presented. The method includes detecting a determined operating condition of a first power converter that is one of a plurality of first power converters in a power generating unit, and the power generating unit is one of a plurality of power generating units. The method further includes responding to detection of the determined operating condition by: controlling, via at least one remaining first power converter of the plurality of first power converters, a load current flowing through a power bus coupled to the plurality of power generating units, and altering one or more droop characteristics corresponding to one or more second power converters disposed in other power generating units based at least in part on the controlled load current flowing through the power bus, wherein the one or more second power converters disposed in other power generating units are coupled to the power bus.

Abstract: A method for controlling an electrical power subsystem includes determining an auxiliary voltage error value based on a measured voltage of the low voltage distribution panel. The method further includes receiving an active current command. The method further includes calculating a switching pattern for a line-side converter of the power converter based on the auxiliary voltage error value and the active current command. A current level produced by the line-side converter controls a voltage to the low voltage distribution panel.

Abstract: An electrical power system connectable to a power grid includes a plurality of electrical power subsystems, each of the plurality of electrical power subsystems including a power converter electrically coupled to a generator having a generator rotor and a generator stator. The electrical power system further includes an intermediate power path extending from each of the plurality of electrical power subsystems for providing power from each of the plurality of electrical power subsystems to the power grid. The electrical power system further includes a zig-zag transformer electrically coupling each of the plurality of intermediate power paths to the power grid, the zig-zag transformer including a primary winding and a plurality of secondary windings, each of the plurality of secondary windings connected to one of the plurality of intermediate power paths, and wherein at least one of the plurality of secondary windings is a zig-zag winding.

Abstract: Systems and methods for operating a power system having a doubly fed induction generator are provided. In example implementations, an electrical power system connected to a power grid can include a generator comprising a stator and a rotor, the stator connected to the power grid via a stator power path, and a power converter. The power converter can include a line-side converter coupled to the power grid via a converter power path and a rotor-side converter coupled to a rotor bus of the rotor and the line-side converter via a DC link, the rotor-side converter configured to convert a DC power on the DC link to an AC signal for the rotor bus. The power system can also include an active filter comprising one or more active controlled components, the active filter being coupled in parallel with the rotor-side converter to reduce harmonics of the electrical power system.

Abstract: Power converters for use in wind turbine systems are included. For instance, a wind turbine system can include a wind driven doubly fed induction generator having a stator and a rotor. The stator is configured to provide a medium voltage alternating current power on a stator bus of the wind turbine system. The wind turbine system includes a power converter configured to convert a low voltage alternating current power provided by the rotor to a medium voltage multiphase alternating current output power suitable for provision to an electrical grid. The power converter includes a plurality conversion modules. Each conversion module includes a plurality of bridge circuits. Each bridge circuit includes a plurality of silicon carbide switching devices coupled in series. Each conversion module is configured to provide a single phase of the medium voltage multiphase alternating current output power on a line bus of the wind turbine system.

Abstract: A power system is presented. The power system includes a first converter including a first output terminal a first control unit coupled to the first converter, a second converter including a second output terminal, where the second converter is coupled in parallel to the first converter, and a second control unit coupled to the second converter. The second control unit is configured to measure a plurality of phase currents at the second output terminal, determine a harmonic current transmitted by the second converter based on single phase current of the plurality of measured phase currents, and change a time-period of at least one switching cycle of a carrier wave of the second converter based on the determined harmonic current to synchronize with a carrier wave of the first converter.

Abstract: A method and a system (111) for operating a hybrid power generation system (100) are presented. the hybrid power generation system (100) includes a wind power generation system (102), a wind power controller (104), a photo-voltaic (PV) power generation system, and a PV power controller (108). The method includes determining a hybrid-level power demand of the hybrid power generation system (100). The method further includes determining respective power demand set-points of the wind power generation system (102) and the PV power generation system (106) based at least in part on the hybrid-level power demand. The method also includes communicating the power demand set-points of the wind power generation system (102) and the PV power generation system (106) respectively to at least one of the wind power controller (104) and the PV power controller (108). A farm (300) having a farm level control system (304) is also presented.

Abstract: Power converters for use in energy systems are included. For instance, an energy system can include an input power source configured to provide a low voltage direct current power. The energy system can include a power converter configured to convert the low voltage direct current power provided by the input power source to a medium voltage multiphase alternating current output power suitable for provision to an alternating current power system. The power converter can include a plurality conversion modules. Each conversion module includes a plurality of bridge circuits. Each bridge circuit includes a plurality of silicon carbide switching devices coupled in series. Each conversion module is configured to provide a single phase of the medium voltage multiphase alternating current output power on a line bus of the energy system.

Abstract: The present disclosure is directed to a method for protecting an electrical power system connected to a power grid. The electrical power system includes at least one cluster of electrical power subsystems. Each of the electrical power subsystems defines a stator power path and a converter power path for providing power to the power grid. The converter power path includes a partial power transformer. The electrical power system further includes a subsystem switch configured with each of the electrical power subsystems and a cluster transformer connecting each cluster of electrical power subsystems to the power grid. A cluster switch is configured with the cluster transformer. A controller is communicatively coupled to each of the plurality of electrical power subsystems. Thus, the controller monitors the electrical power system for faults, and if a fault is detected in the cluster, sends, via one of the subsystem switches or the power converters, a block signal to the cluster switch.

Abstract: A method for optimizing reactive power generation of an electrical power system includes generating, via a plurality of cluster-level controllers, a cluster-level reactive power command for each cluster of electrical power subsystems based on a system-level reactive power command. The method also includes determining, via the cluster-level controllers, a subsystem-level reactive power command for each of the electrical power subsystems based on the cluster-level reactive power command. Further, the method includes evaluating, via a plurality of subsystem-level controllers, reactive power capability of a plurality of reactive power sources within each of the electrical power subsystems. Moreover, the method includes generating, via each of the subsystem-level controllers, an actual reactive power for each of the electrical power subsystems based on the evaluation by allocating a portion of the subsystem-level reactive power command to each of the plurality of reactive power sources.

Abstract: A power system is presented. The power system includes a first converter including a first output terminal a first control unit coupled to the first converter, a second converter including a second output terminal, where the second converter is coupled in parallel to the first converter, and a second control unit coupled to the second converter. The second control unit is configured to measure a plurality of phase currents at the second output terminal, determine a harmonic current transmitted by the second converter based on single phase current of the plurality of measured phase currents, and change a time-period of at least one switching cycle of a carrier wave of the second converter based on the determined harmonic current to synchronize with a carrier wave of the first converter.

Abstract: A method for isolating faults in an electrical power system connected to a power grid includes dividing the electrical power system into a plurality of power modules each including a plurality of electrical power subsystems and a substation. Each of the electrical power subsystems defines a stator power path and a converter power path for providing power to the power grid and having a partial power transformer. The method also includes coupling each of the power modules to the power grid via a primary electrical line. Further, the method includes monitoring the electrical power system for faults. In response to detecting a fault in one of the power modules, the method includes isolating the fault to the power module experiencing the fault. In contrast, if the fault is detected in the primary electrical line or the power grid, the method includes tripping the electrical power system.

Abstract: Systems and methods for operating a power system having a doubly fed induction generator are provided. In example implementations, a power system can include a power converter. The power converter can include a line-side converter, a DC link, and a rotor-side converter. The rotor-side converter is configured to convert a DC power on the DC link to an AC signal for a rotor bus. The system can include a control system having one or more control devices.

Abstract: An electrical power system includes a system-level controller and a plurality of clusters of subsystems defining a stator power path and a converter power path for providing power to the power grid. The converter power path includes a partial power transformer. The system further includes a cluster transformer connecting each cluster to the power grid and a plurality of cluster-level controllers communicatively coupled with the system-level controller. Each of the clusters is communicatively coupled with one of the cluster-level controllers. Thus, the system-level controller regulates system-level active and/or reactive power based on required active or reactive power for the system, respectively, and compares the system-level active or reactive power with preferred values thereof.

Abstract: The present disclosure is directed to a protection system for a wind turbine power system connected to a power grid. The protection system includes a main brake circuit having at least one brake resistive element and at least one brake switch element, a battery system, and a controller. The brake resistive element is coupled to at least one of a DC link of a power converter of the wind turbine power system, windings of a rotor of the generator, or windings of a stator of a generator of the wind turbine power system via the brake switch element. The battery system is coupled to the generator via a battery switch element. In addition, the controller is configured to disconnect the power converter and the generator from the power grid and connect at least one of the main brake circuit or the battery system to the generator in response to detecting an electromagnetic (EM) torque loss event so as to generate an EM torque.

Abstract: A power generation system (101) is disclosed. The power generation system (101) includes a variable speed engine (106) and a DFIG (108) coupled thereto. The DFIG (108) includes a generator (112), a rotor side converter (114), and a line side converter (116) electrically coupled to the generator (112). The rotor side converter (114) is configured to aid in operating the generator (112) as motor to crank the variable speed engine (106). The power generation system (101) further includes a PV power source (110) and/or an energy storage device (122) electrically coupled to a DC-link (118) between the rotor side converter (114) and the line side converter (116). A method of cranking the variable speed engine is also disclosed.

Abstract: A power system is presented. The power system includes a first converter including a first output terminal a first control unit coupled to the first converter, a second converter including a second output terminal, where the second converter is coupled in parallel to the first converter, and a second control unit coupled to the second converter. The second control unit is configured to measure a plurality of phase currents at the second output terminal, determine a harmonic current transmitted by the second converter based on single phase current of the plurality of measured phase currents, and change a time-period of at least one switching cycle of a carrier wave of the second converter based on the determined harmonic current to synchronize with a carrier wave of the first converter.

Abstract: Systems and methods for operating a power converter are provided. A DC to AC converter can include an inner converter and an outer converter. The inner converter can include an isolation transformer a first plurality of switching devices. The outer converter can include a second plurality of switching devices. A control method can include determining an output voltage of the outer converter. The control method can further include controlling operation of the inner converter based at least in part on the output voltage of the outer converter.