Methods of operating a grid ancillary service with an uninterruptible power supply (GAUPS) device are provided. A method of operating a GAUPS device includes controlling a switch of the GAUPS device in response to a signal that is generated by the switch, to control efficiency of an inverter and quality of power supplied to a load via the inverter. The switch is coupled between the inverter and the load. Related systems and devices are also provided.

SOGI based apparatus and methods for providing balanced three phase output signals free of harmonics, DC components and imbalance present in the input signals, are disclosed. In addition, such apparatus and methods for providing corresponding output signals which are drift-free integrals of the input signals and which signals may enable the control of a power electronics inverter for improved and robust grid power injection and for motor control are disclosed.

A station building power supply includes: a power converter that converts DC power to AC power; a casing that houses the power converter; an AC system circuit that supplies the AC power output from the power converter to electrical apparatus outside the casing; and a filter circuit that applies a high-frequency current generated in the power converter from the AC system circuit to the casing. In the station building power supply, the power converter and the casing are grounded.

A harmonic current compensating device according to an embodiment of the present disclosure is a harmonic current compensating device including a power converter including at least a pair of arms each including a switching element, the harmonic current compensating device being configured to drive the switching element and supply compensating current to load current flowing between a system power source and a harmonic generating load, in which the switching element includes a unipolar device using a wide bandgap semiconductor.

A power conversion system including a plurality of power conversion devices connected in parallel. Each of the plurality of power conversion devices includes: a power conversion circuit configured to convert DC to AC; and an AC filter circuit connected to an output side of the power conversion circuit. The AC filter circuit is an LC low-pass filter including a first filter reactor and an AC filter capacitor connected in an L shape. The AC filter circuit further includes a second filter reactor connected in series to the AC filter capacitor, and a resistance constructing a series circuit together with the AC filter capacitor and the second filter reactor.

A measurement data based method for identifying wind turbine generators which cause sub-synchronous oscillations in a complex power system has a theoretical foundation of the open-loop modal resonance and the parallel filter design. The advantages of the present invention are as follows. 1) The present invention can identify the wind turbine generators which cause the SSOs in the complex power system using measurement data instead of parametric model. Hence, it simplifies the computation and reduces the modeling cost effectively. 2) The present invention can identify the wind turbine generators which cause the SSOs in the complex power system precisely with reduced amount of measurement data, reducing the cost of hardware and data measurement effectively. 3) The present invention can identify the wind turbine generators which cause the SSOs in the complex power system based on the open-loop modal resonance theory.

A power supply system includes a plurality of power conversion devices, a plurality of breakers, and a controller. The plurality of breakers are respectively connected to the plurality of power conversion devices and configured to perform switching of an electrical connection between the power conversion device and a power system, wherein the breaker switches an ON state and an OFF state. The controller is configured to control the breakers and switch connection states of the plurality of power conversion devices are switched, and the controller being configured to determine whether or not the connected breaker is in an ON state and electrically conducted to the power system and the number of the power conversion devices in a standby state reaches a predetermined number.

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.

Provided is an uninterruptable power supply device. An uninterruptable power supply device 100, which is provided between a commercial power system 10 and an essential load 30 and which provides AC power to the essential load 30, wherein the uninterruptable power supply device 100 is provided with: a power supply unit 2, which has a power converter 22 and a storage battery 21 and which is connected to a power line L1; an open switch 3 for opening the power supply line L1; a system abnormality detection unit 5 for detecting a system abnormality, which is at least one of voltage rise, phase fluctuation, voltage imbalance, harmonic abnormality, and flicker, in addition to at least one of frequency fluctuation and voltage drop including instantaneous voltage drop; and a control unit 6 which, opens the open switch 3 and supplies AC power to the essential load 30.

A control node enables distributed grid control. The control node monitors power generation and power demand at a point of common coupling (PCC) between a utility power grid and all devices downstream from the PCC. The control node can have one or more consumer nodes, which can be or include customer premises, and one or more energy sources connected downstream. The control node monitors and controls the interface via the PCC from the same side of the PCC as the power generation and power demand. The control can include adjusting the interface between the control node and the central grid management via the PCC to maintain compliance with grid regulations at the PCC.