A power conversion device includes: a power converter connected to an AC grid to which a load is connected; and a control circuit. The control circuit includes a harmonic compensation unit that includes a current command generation unit and a limit coefficient calculation unit and compensates for harmonic current contained in load current. The current command generation unit generates compensation current desired values for respective frequency components, and corrects the compensation current desired values using corresponding limit coefficients, to generate compensation current commands for respective frequency components. The limit coefficient calculation unit calculates each limit coefficient, on the basis of the compensation current desired value for each frequency component, and maximum voltage and maximum current that the power converter can output.

Provided is an active filter circuit connected to a power-receiving terminal of a power line for an alternating-current power supplied to a power converter device from an alternating-current power grid or a direct-current power source interconnected with the alternating-current power grid, or for a direct-current power supplied from the direct-current power source for reducing a harmonic component of a conduction noise propagating to the power line and outputting the reduced harmonic; and a controller for monitoring a variation in the state of an input power entering a power source module for generating drive power for an active element constituting the active filter circuit, or a variation in the state of the drive power supplied from the power source module, and diagnosing an abnormality of a circuit operation for a circuit including the active element of the active filter circuit therein.

A method for operation of UPS modules connected in parallel is provided. The method includes: in a case that a UPS system is constructed based on multiple UPS modules connected in parallel, sleeping, based on a system load rate, a predetermined number of UPS modules to control the UPS system to operate at a predetermined efficiency level; controlling UPS modules not being slept in the UPS system to enter into a main-inverter power supply mode or a main-bypass common mode to perform reactive power and harmonic compensation; and waking up the slept UPS modules when the system load rate drops by a predetermined value due to a sudden addition of a load. The UPS modules can be slept or waked up intelligently based on the system load rate in the dynamic online mode, ensuring that the UPS system operates around highest efficiency.

The present disclosure relates to a device of monitoring a reactive power compensation system to compensate reactive power, the device including a measurement unit configured to acquire voltage data, current data, and a phase angle from each constituent device, a power performance index calculation unit configured to calculate power performance index data including at least one of power factor data, flicker data, and harmonics data based on the acquired voltage data, current data, and phase angle, and a controller configured to analyze and evaluate the calculated power performance index data based on a preset situation.

An anti-power environment suppression circuit includes: a power input terminal configured to receive an alternating current input from an external power source; a power output terminal configured to output the alternating current that has undergone anti-interference processing; a live wire, a neutral wire and a ground wire that are coupled in parallel between the power input terminal and the power output terminal; and a common-mode suppression sub-circuit coupled in the ground wire. The common-mode suppression sub-circuit is further coupled to the live wire and the neutral wire, and the common-mode suppression sub-circuit is configured to suppress common-mode interference between the ground wire and the live wire, and suppress common-mode interference between the ground wire and the neutral wire, so as to perform the anti-interference processing on the input alternating current.

The present application provides a wind turbine and a converter filter capacitor switching control method, device and system therefor. The method includes: acquiring a contactor delay influence factor of the converter and an approximate zero voltage period of the power grid connected to the wind turbine, wherein an absolute value of a voltage of the power grid in the approximate zero voltage period is less than an approximate zero voltage threshold; obtaining a contactor delay duration according to the contactor delay influence factor, wherein the contactor delay duration is a duration from when the contactor receives a switching instruction to when the contactor is switched on or off; determining a switching time point of the filter capacitor based on the approximate zero voltage period and the contactor delay duration; transmitting the switching instruction to the contactor when the switching time point is reached.

A converter apparatus includes a string of electrically interconnected modules that includes a first group of modules comprising a first module and a second group of modules comprising a second module. A first screen is connected to a first defined electric potential and is located adjacent the first group of modules and a second screen is connected to a second defined electric potential and is located adjacent the second group of modules. During operation of the converter apparatus a resonance loop is created from the first module via the first and second screens and the second module back to the first module. A damping unit is located in the resonance loop and is set to dampen electromagnetic noise.

Disclosed are semi non-magnetic bobbins for use in core reactors, and core reactors that include the semi non-magnetic bobbins. The semi non-magnetic bobbins are made of a non-metallic material and provide core reactors that can withstand high temperatures and at the same time avoid eddy current effects. The disclosed semi non-metallically permeable bobbins also do not adversely affect electrical power quality and save power and can be used to capture harmonics currents. When properly designed and arranged can be used to provide electromagnetic induction heaters using harmonics currents imported from an electrical power system as the working source of heat and provide a zero-cost heating process.

Provided are hybrid passive power filter and a three-phase power system. The hybrid passive power filter includes: a series passive harmonic isolation unit, a parallel passive filtering unit, and a harmonic load; the series passive harmonic isolation unit has an input terminal electrically connected to a power grid and an output terminal electrically connected to a first terminal of the harmonic load, and the series passive harmonic isolation unit is configured to isolate harmonics; and the parallel passive filtering unit has an input terminal electrically connected to the output terminal of the series passive harmonic isolation unit and an output terminal electrically connected to a second terminal of the harmonic load, and the parallel passive filtering unit is configured to filter out harmonics.

A generator system can include a generator configured to produce an output of alternating current (AC), a rectifier connected to the generator to rectify the AC into direct current (DC) rectifier output, an inverter connected to the rectifier to receive the DC rectifier output and configured to output three phase AC inverter output, and a plurality of output lines connected to the inverter to receive the three phase AC inverter output. The system can include a control module configured to control the output of the inverter. The control module can be operatively connected to one or more of the output lines via one or more local sense leads to receive a local feedback. The control module can be configured to control the inverter as a function of the local feedback to provide one or more of protection, voltage regulation, or harmonic correction.