A doubly-fed induction generator (DFIG) system (100) is described. The DFIG system (100) includes an induction electric machine (102) including a stator having a stator winding and a rotor having a rotor winding. The stator winding is electrically connected to at least one output terminal (108) and the rotor winding is electrically connected to the at least one output terminal (108) by means of a power converter. The power converter includes a first active rectifier/inverter (130a) with alternating current AC terminals electrically connected to the rotor winding, and direct current DC terminals, and a second active rectifier/inverter (136a) with DC terminals electrically connected to the DC terminals of the first active rectifier/inverter by a DC link (138a), and AC terminals electrically connected to the at least one output terminal (108). A controller is adapted to control the first active rectifier/inverter (130a) so that the frequency of the AC current at its AC terminals is substantially constant during at least one of a “line charging mode” and an “islanded mode”.

A secondary magnetic excitation generator-motor device that inputs a first ignition pulse command to a three-level NPC power converter such that a detected excitation current value corresponds with an excitation current command value, the secondary magnetic excitation generator-motor device having a function of identifying a first phase, a second phase, or a third phase in descending order of a current absolute value, wherein a pulse switch to output an ignition pulse command to the three-level NPC power converter switches the ignition pulse command to the second ignition pulse command when a current absolute value exceeds a set overcurrent level 1, and switches the ignition pulse command to the first ignition pulse command when current absolute values for three phases are all equal to or smaller than a set overcurrent level 2.

Systems and methods are provided for braking a translator of a linear multiphase electromagnetic machine. The system detects a fault event, and in response to detecting the fault event, causes the translator to brake using an electromagnetic technique. Braking includes causing the translator to stop reciprocating, by applying a force opposing an axial motion, which may occur within one cycle, or over many cycles. The fault event may include, for example, a fault associated with an encoder, a controller, an electrical component, a communications link, a phase, or a subsystem. The system includes a power electronics system configured to apply current to the phases. The system may use position information, current information, operating parameters, or a combination thereof to brake. Alternatively, the system need not use position information, current information, and operating parameters, and may brake the translator independent of such information.

Protection devices prevent damage to synchronous generators during loss-of-field events. In various embodiments, a first protective element is associated with a first protection zone to protect a generator from a loss-of-field event at full load. A second protective element is associated with a second protection zone to prevent thermal overload during underexcited operation of the generator and to protect from loss-of-filed at light load. A third protective element associated with a third protection zone limits operation of the generator within the generator's specific steady-state stability limits. A fourth protective element is associated with a fourth protection zone to provide an alarm prior to operation of the second protective element. In various embodiments, characteristics and limits of each of the protective elements are defined in the same plane (specifically, the P-Q plane) to simplify settings and allow for visualization of the element characteristics and the generator capability curve at one or more temperatures or cooling capacities.

A method for operating a power generation system that supplies real and reactive power to a grid includes receiving a reactive power demand made on the power generation system at an operating state of the power generation system and a grid state. Further, the method includes decoupling reactive power control and voltage control between a generator and a reactive power compensation device so as to reduce an oscillatory response of a reactive power output from the reactive power compensation device and the generator. Moreover, the method includes operating, via a device controller, the reactive power compensation device in a reactive power control mode to generate at least a portion of the reactive power demand.

A generator system includes a generator including terminals, a generator circuit breaker coupled to the terminals and that couples and decouples the generator from a power grid, multiple sensors, and a controller that operates the generator system. The controller determines whether an active power is less than a reverse active power threshold and whether one or more turbine valves are closed, and determines that a breaker failure has occurred based on the active power being less than the reverse active power threshold and the one or more turbine valves being closed. If the active power remains less than the reverse active power and the turbine valves remain closed after a threshold time period after the trip command, and if a reactive power is less than a reverse reactive power threshold, then a breaker failure has occurred. In response, the controller may transmit another trip command to the generator circuit breaker to initiate the breaker failure protection.

A method for operating an asynchronous inverter-based resource connected to a power grid as a virtual synchronous machine to provide grid-forming control thereof includes receiving a frequency reference command and/or a voltage reference command. The method also includes determining at least one power reference signal for the inverter-based resource based on the frequency reference command and/or the voltage reference command. Further, the method includes generating at least one current vector using the power reference signal(s). Moreover, the method includes determining one or more voltage control commands for the inverter-based resource using the at least one current vector. In addition, the method includes controlling the inverter-based resource based on the one or more voltage control commands such that the inverter-based resource actively participates in controlling at least one of voltage and frequency at a point of interconnection between the inverter-based resource and the power grid in a closed loop manner.

A method for controlling an inverter-based resource having an asynchronous machine connected to a power grid to provide grid-forming control of the inverter-based resource includes coupling at least one additional device to terminals of a first converter of the inverter-based resource. Further, the method includes emulating, via a controller, at least one of the at least one additional device or the first converter as a first virtual synchronous machine. Moreover, the method includes coordinating, via the controller, operation of the first virtual synchronous machine and a second converter of the inverter-based resource using a vector-control approach to control at least one of voltage and frequency at a point of interconnection between the inverter-based resource and the power grid in a closed loop manner.

A flexible intelligent electrical switching device with multi-function capability, and methods of use are presented herein which provide an autonomous, reconfigurable switching device. The present disclosure is specifically designed to reduce space, cost of manufacture, efficiency, installation reduction time and ease of implementation.

A flexible intelligent electrical switching device with multi-function capability, and methods of use are presented herein which provide an autonomous, reconfigurable switching device. The present disclosure is specifically designed to reduce space, cost of manufacture, efficiency, installation reduction time and ease of implementation.