An apparatus for charging a battery for a vehicle, includes a PFC circuit including a rectifier for rectifying an AC power to a DC power, and a link capacitor for smoothing the rectified DC power, a bidirectional DC-DC converter including a first switch for converting the DC power of the PFC circuit to an AC power, a transformer for boosting or reducing a voltage of the AC power converted at the first switch, and a second switch for rectifying an AC power from the transformer to a DC power, and a controller configured to control a phase of a PWM signal applied to the second switch such that the link capacitor is charged by an electrical power from the battery, when a voltage of the link capacitor is below a predetermined voltage prior to entering the battery charging mode.

A load apparatus is connected to an AC power source and is supplied with power from the AC power source. An operation state control unit controls, based on a target value about a power-source quality including either a power-source power factor of the AC power source or a power-source harmonic of the AC power source and on a present power-source quality, an operation state of the load apparatus.

A controller performs a first control for controlling the power source power factor or a power source harmonic of the harmonic current such that an input power factor of at least one of a plurality of connection devices changes in a direction preceding the power source power factor in a case where the power source power factor changes in a lagging direction, and performs a second control for controlling the power source power factor or the power source harmonic such that the input power factor of at least one of the connection devices changes in a direction lagging behind the power source power factor in a case where the power source power factor changes in a leading direction.

An active filter device includes a power module configured to generate a compensating current to suppress a harmonic current generated from a load device and a controller configured to control the power module. The controller includes a current command calculation unit configured to calculate a compensating current command to suppress the harmonic current, a control variable calculation unit configured to calculate a control variable based on a deviation between the compensating current command and an actual compensating current, a duty cycle calculation unit configured to calculate duty cycle of each of three phases based on the control variable, a duty cycle modulation unit configured to perform two-phase modulation on the duty cycle of each of three phases, and a control signal generation unit configured to, after the two-phase modulation, generate, from the duty cycle of each of three phases, a control signal to drive the power module.

An apparatus, for charging a battery for a vehicle, includes a PFC circuit comprising a rectifier for rectifying an AC power to a DC power, and a link capacitor for smoothing the rectified DC power, a bidirectional DC-DC converter including a first switch for converting the DC power of the PFC circuit to an AC power, a transformer for boosting or reducing a voltage of the AC power converted at the first switch, and a second switch for rectifying an AC power from the transformer to a DC power, and a controller configured to control a phase of a PWM signal applied to the second switch such that the link capacitor is charged by an electrical power from the battery, when a voltage of the link capacitor is below a predetermined voltage prior to entering a battery charging mode.

Aspects of the present invention relate to a method for controlling an amount of reactive current provided from a wind turbine generator to a power grid during an abnormal power grid event, said wind turbine generator comprising a doubly-fed induction generator having a rotor and a stator, and a power converter coupling the rotor to the power grid, the power converter comprising a grid-side inverter, wherein the method comprises the step of balancing the reactive current provided to the power grid between a reactive stator current and a reactive grid-side inverter current, wherein the reactive grid-side inverter current is controlled in accordance with a reactive current capacity of a grid breaker receiving the reactive current provided by the grid-side inverter. Aspects of the present invention also relate to a wind turbine generator being capable of performing the method.

DC power distribution systems and corresponding methods are disclosed herein. One method includes performing a first voltage conversion using an active rectifier to convert a first input AC voltage to a first output DC voltage and supplying the first output DC voltage from the active rectifier to a DC bus. The first output DC voltage from the DC bus is provided to a second input at a bucking cell-stack regulator, and a second voltage conversion, from the second input DC voltage to a second output DC voltage, is performed using the bucking cell-stack regulator. The second output DC voltage is applied to a DC load.

A system and a method for locally controlling delivery of electrical power along the distribution feeder by measuring certain electricity parameters of a distribution feeder line using a substation phasor measurement unit (PMU) electrically coupled to a substation distribution bus at a first node on the feeder line, and at least one customer site PMU electrically coupled to a low voltage end of a transformer at a customer site, wherein the transformer is coupled by a drop line to a second node on the distribution feeder line and the customer site is coupled by another drop line to the transformer, and by controlling at least one controllable reactive power resource and optionally a real power resource connected to the second node or at the customer site. Related apparatus, systems, articles, and techniques are also described.

Distributed grid intelligence can enable a modular power grid. Multiple consumer nodes are coupled to a same point of common coupling (PCC). Local power sources are coupled to the PCC. None of the power sources has sufficient generation capacity alone to meet peak demand of the multiple consumer nodes of the grid segment. The grid segment includes multiple control nodes to control distribution of power from the power sources to the multiple consumer nodes based on power demand from the multiple consumer nodes and based on operation of the other power sources. Thus, consumer nodes can share power generated locally, but operate independently without the need for central management or a central power plant, and different independent segments can be coupled to each other to expand the grid network.

Distributed grid network intelligence enables intelligent local energy storage backup control. A consumer node includes a local energy storage system. A distributed control node for the consumer node monitors local power demand and local energy generation. The control node calculates an interface operation for accessing energy from the local energy storage or charging the local energy storage, based on the local power demand and the local energy generation. The control node triggers a local power converter to execute the interface operation with the local energy storage.