An electrical system for controlling a wind turbine is provided. The electrical system includes a first resistive element, a storage element and a controller. The first resistive element and the storage element are coupled to a DC link of the wind turbine. The controller is used for switching between the first resistive element and the storage element in response to a grid side fault condition to minimize mechanical loads induced by the grid side fault condition.

A thermal power generation apparatus includes a control circuit that selects a single operation mode from among a plurality of modes including a normal mode and a specific mode on the basis of a voltage in a commercial system. The normal mode is an operation mode in which alternating-current power output from an inverter is adjusted so that a direct-current voltage in a direct-current power line follows a target voltage. The specific mode is an operation mode in which direct-current power absorbed by an electric power absorber and/or the amount of heat per unit time supplied to a heat engine are/is adjusted so that the direct-current voltage follows the target voltage.

Methods for operating a wind turbine system are provided. In one embodiment, a method includes adjusting a threshold direct current (DC) bus voltage for a dynamic brake in a wind turbine power converter above a reference DC bus voltage based on at least one system condition. The method further includes gating the dynamic brake on when an experienced DC bus voltage is equal to or greater than the threshold DC bus voltage, and inputting a dynamic brake condition into a controller when the dynamic brake is gated on. The method further includes determining if a grid fault has occurred, reducing power generation of the wind turbine if no grid fault has occurred, and blocking the power converter if a grid fault has occurred. The method further includes gating the dynamic brake off when the experienced DC bus voltage is less than the threshold DC bus voltage.

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.

Automatic voltage regulation is shown involving full wave rectifying a power signal and generating a reference corresponding to an operating voltage level, line sampling the power signal and comparing it to the reference to generate a line sync signal synchronized to the power signal. Producing 90 out of phase signals synchronized to the line sync signal with a PLL locked onto the line sync signal that outputs a phase error signal. Generating a quadrature signal from the phase signals. Sampling the peaks of the rectified power signal using the quadrature signal to produce a control signal. Subtracting the error signal and damping signal from the reference to produce a duty cycle modulation signal. The duty cycle modulation signal controls a duty cycle of a field voltage control signal that oscillates at a predetermined frequency. The field voltage control signal is low-pass filtered to produce the damping signal. The control signal is utilized to detect a short circuit condition and engage a circuit protection device. The reference voltage may also be obtained from another generator so that the output voltage is controlled to operate in sync with the other generator.

A method for controlling a multi-phase electric machine, whose phase terminals in an active bridge rectifier are respectively connected, via controllable first current valves, to a first DC voltage terminal and via second current valves to a second DC voltage terminal. The method includes switching on the first current valves when an output voltage between the first DC voltage terminal and the second DC voltage terminal has exceeded an upper threshold value at an exceedance point in time, and shutting off the first current valves again only once the output voltage has subsequently fallen below a lower threshold value at a shortfall point in time. The first current valves are shut off again after the shortfall point in time individually, and each only when a respective indication value, which characterizes a current flow in the phase terminal associated with the respective current valve, exhibits a predetermined property.

An electromagnetic braking system includes an electrically conductive disc coupled to a rotatable shaft of a power generation system for operating in an island mode. The rotatable shaft is operatively coupled between a prime mover and a generator for supplying power to an island grid. The electromagnetic braking system further includes a controller for receiving at least one status or synchronization signal and for generating a control signal based on the at least one signal and an inducting unit for applying an electromagnetic braking force on the electrically conductive disc when commanded by the control signal to regulate a rotational speed of the rotatable shaft.

A power dissipating arrangement for dissipating power from a generator in a wind turbine is provided. The generator comprises a plurality of output terminals corresponding to a multi-phase output. The power dissipating arrangement comprises a plurality of dissipating units, a plurality of semiconductor switches, a trigger circuit for switching the semiconductor switches and a control unit for controlling the operation of the trigger circuit, thereby controlling the switching of the semiconductor switches.

A device for increasing fault clearing time is provided having a component part designed to identify a short circuit event and load resistors connectable in the event of a fault such that the turbine power transmitted to the shaft is electrically absorbed by the generator and converted into heat until the grid comes back online.

Disclosed is an alternator overvoltage protection circuit having a TRIAC and a MOSFET. The TRIAC is electrically connected to the MOSFET and the TRIAC is electrically connected to a magneto. The TRIAC is configured to ground the magneto when triggered by the MOSFET. The MOSFET is electrically connected to an alternator and configured to conduct when the alternator operates in an overvoltage condition. Also disclosed is a method of alternator overvoltage protection for a piece of outdoor power equipment, the method including providing a TRIAC and an alternator rotated by an engine having a magneto, wherein the alternator outputs a voltage when rotated by the engine. The method further includes configuring the TRIAC to ground the magneto when the alternator operates in an overvoltage condition, thereby disabling the magneto, which stops the rotation of the engine and stops the alternator from outputting voltage.