Enhanced network power factor corrective designs are presented that can use corrective devices that achieve long-term, operationally stable mechanical work. Embodiments can utilize reverse-winding induction motor designs with engineerable parameters and configurations for the reverse winding (13) in systems and through methods where an inductive motor (1) can present a current that leads voltage and a leading power factor (16) to correct other existing induction motors (8) in an initial network (9) or be optimized for a particular application. Designs also present a power factor correction that can present a variable correction without altering the character or physical capacitive value of an electrical correction component. Individual induction motors that have leading current and a leading power factor (16) can be provided to improve reverse winding induction motors. Progressive start controls (23) can also be used in a manner that limits inrush current to operational levels with passive current establishment control where reverse winding (13) effects can be used and perhaps even delayed to passively limit and even effect a current decrease while rotational acceleration continues after initial start transition.

A method for maintaining sufficient reactive current margin in a power system connected to a power grid includes receiving, via a power limiter system, a reactive current command and an upper reactive current limit for the power system. The method also includes determining, via the power limiter system, a reactive current margin signal as a function of the reactive current command and the upper reactive current limit. Further, the method includes generating, via the power limiter system, a power command signal based on the reactive current margin signal. Moreover, the method includes controlling, via a system controller, operation of the power system based at least partially on the power command signal.

A circuit for delivering electrical energy to an AC mains connection is disclosed. The circuit includes a voltage source and a switch connected between the voltage source and the AC mains connection. The switch operates to transfer current from the voltage source to the AC mains. The circuit further includes a controller to control the switch. The controller operates to generate a simulated signal that represents a waveform of the AC mains without any distortion present on the waveform of the AC mains.

A control unit of an electric motor control device includes an inverter circuit 6 that supplies power to an electric motor, a current control unit that outputs a voltage command value as a drive command of the inverter circuit, a current detecting unit that detects current flowing to each phase of the electric motor, and a failed phase identifying unit that identifies a location of a failure in the current detecting unit. The failed phase identifying unit determines whether or not a magnitude or a phase of a frequency component of the test voltage command included in a detected current value when the inverter circuit is driven with a test voltage command having a frequency higher than a rotational frequency of the electric motor as a drive command is within a predetermined range, and determines that a failure has occurred in a phase that is not within the predetermined range.

A method for operating an unbalanced load manager for a three-phase induction motor or heater, includes receiving, by a load manager, values representative of current flow sensed by current sensors and voltages sensed by voltage taps corresponding to phases of a three-phase power system providing power to the motor or heater. The method includes detecting, by the load manager, a transition from positive or negative to zero current, to measure a phase shift between line-to-line and current. The method further includes synchronizing, by the load manager, firing from line-to-line signal to line-to-neutral signal of phases of the three-phase power system, using the measured phase shift between line-to-line and current.

This disclosure is directed to a method for operating a wind farm having a plurality of wind turbines and to a control system for a wind farm. The wind farm is connected to an electrical grid. The wind turbines are operated to supply electrical power to the electrical grid in accordance with at least one setpoint value for a power related electrical variable. In the event that an available reactive power of the wind farm is smaller than a setpoint for a reactive power to be supplied by the wind farm, a required increase of reactive power is determined for each wind turbine of the wind farm.

In general, the subject matter described in this disclosure can be embodied in a system that implements power supply protection. The system includes first circuitry, second circuitry, a first power supply that is configured to power the first circuitry, and a second power supply that is configured to power the first circuitry and the second circuitry. The system also includes a power supply sensor including an input that is connected to the first power supply, and an output. The system also includes a hysteresis buffer including an input that is connected to the output of the power supply sensor, and an output that is connected to the first circuitry in a configuration that transitions the first circuitry to a protected state as a result of the hysteresis buffer transitioning output states.

A configuration of switches added to a line control circuit allows for switching back and forth between a configuration featuring a series-connected thyristor switch and reactor and a configuration featuring a parallel-connected thyristor switch and reactor. Connecting the reactor in series with the thyristor switch allows a controlled high-impedance circuit configuration that is particularly well adapted for cold furnace start-ups and furnace idling. In this manner, there is reduced need for such equipment as extra startup transformers, alternate low-voltage power supply configurations and temporary specialty electrical apparatus for cold furnace start-ups.

A method and system of power factor optimization and total harmonic distortion are provided under the premise of efficient power management and distribution on an electrical grid. The method and system include a novel optimization technique based on a novel current profiling methodology enabling real-time power management with power factor correction as a function of the optimization. The optimization can be performed under dynamic current constraints. When deployed on an electrical grid, the method and system can provide a new technique for power management targeting an efficiency of the electrical grid. The method and system can thus provide for reduced costs of energy production and reduced carbon emissions into the atmosphere.

A device for testing a power module of a set of power modules connected together includes reactive power compensation means capable of compensating the reactive power transferred between a tested power module and the other power modules, and means for monitoring the power generated by the tested power module including means for comparing said generated power with at least one threshold value.