A power conversion device includes a power conversion circuit and a power conversion control circuit. The power conversion control circuit is configured to calculate a positive-phase sequence current command signal based on a positive-phase sequence voltage of the three-phase AC output voltage and a positive-phase sequence current of the three-phase AC output current, calculate a negative-phase sequence current command signal based on the first axis negative-phase sequence current command value, the second axis negative-phase sequence current command value, the first axis negative-phase sequence current value, and the second axis negative-phase sequence current value, and generate the switching control signal based on the positive-phase sequence current command signal and the negative-phase sequence current command signal.

A method of operating a charging system may include connecting the charging system to a power grid with a plurality of phases, measuring a plurality of phase currents of the plurality of phases at a balance point, and transmitting a plurality of performance targets to a plurality of electrical consumers connected to one of a plurality of charging points of the charging system. The method may also include changing a performance target of the plurality of performance targets for each of the plurality of charging points individually for a predetermined test time interval and measuring a corresponding change of the plurality of phase currents at the balance point. The method may further include, based on the corresponding change of the plurality of phase currents, determining whether an electrical consumer charges with a significant current and whether the electrical consumer could charge with a higher current.

A method of operating a charging system may include connecting the charging system to a power grid with a plurality of phases, measuring a plurality of phase currents of the plurality of phases at a balance point, and transmitting a plurality of performance targets to a plurality of electrical consumers connected to one of a plurality of charging points of the charging system. The method may also include changing a performance target of the plurality of performance targets for each of the plurality of charging points individually for a predetermined test time interval and measuring a corresponding change of the plurality of phase currents at the balance point. The method may further include, based on the corresponding change of the plurality of phase currents, determining whether an electrical consumer charges with a significant current and whether the electrical consumer could charge with a higher current.

A method for providing grid-forming control of an inverter-based resource includes receiving a negative-sequence voltage feedback of the inverter-based resource. The method also includes receiving at least one negative-sequence feedback signal of the inverter-based resource. The method also includes determining, via a negative-sequence regulator, one or more control signals indicative of a desired negative-sequence impedance of the inverter-based resource using the at least one negative-sequence feedback signal. Further, the method includes generating, via the negative-sequence regulator, a control command for the inverter-based resource based on the one or more control signals. Moreover, the method includes controlling the inverter-based resource based on the control command to achieve the desired negative-sequence impedance of the inverter-based resource.

A method for controlling a chain-link power converter including three phase legs, each of which phase legs includes a plurality of series-connected converter cells, each of the cells including a DC capacitor, the phase legs being connected in a delta configuration. The method includes detecting an unsymmetrical voltage condition at a terminal of the converter; determining a ratio between a zero sequence and a negative sequence component of a compound current to be injected into the converter, based on the detected unsymmetrical voltage condition; calculating the compound current comprising the zero sequence component and the negative sequence component in accordance with the determined ratio; and injecting the compound current into the converter to control the converter in view of the detected unsymmetrical voltage condition.

A method for controlling a chain-link power converter including three phase legs, each of which phase legs includes a plurality of series-connected converter cells, each of the cells including a DC capacitor, the phase legs being connected in a delta configuration. The method includes detecting an unsymmetrical voltage condition at a terminal of the converter; determining a ratio between a zero sequence and a negative sequence component of a compound current to be injected into the converter, based on the detected unsymmetrical voltage condition; calculating the compound current comprising the zero sequence component and the negative sequence component in accordance with the determined ratio; and injecting the compound current into the converter to control the converter in view of the detected unsymmetrical voltage condition.

An embodiment relates to a switchgear for a single-phase motor and a three-phase motor, the switchgear including a processing unit and a first, second and third current path, the first and third current path each including a current transformer. The processing unit is adapted to detect the current I.sub.1 of the first current path and the current I.sub.3 of the third current path. To provide a cost-effective switchgear for a one-phase motor and a three-phase motor which is adapted to identify the failure of every single phase in the three-phase operation and a phase failure in the one-phase operation, the processing unit is designed such as to detect the currents I.sub.1, I.sub.3 of the first and third current path and to determine, based on the phase shift between the detected currents I.sub.1, I.sub.3 of the first and third current path in which operating mode the switchgear is operated.

A measurement apparatus includes a measurement unit having two or more of a first measurement unit configured to measure an electricity related value of a wireway branched from a wireway to be measured to which a star-connected three-phase AC power source is connected, a second measurement unit configured to measure an electricity related value of a wireway branched from a wireway to be measured to which a star-connected three-phase AC power source is connected, a third measurement unit configured to measure an electricity related value of a wireway branched from a wireway to be measured to which a delta-connected three-phase AC power source is connected, and a fourth measurement unit configured to measure an electricity related value of a wireway branched from a wireway to be measured to which a delta-connected three-phase AC power source is connected, and a selection processor configured to select any one of the measurement units.

A method comprises, at a power balancing circuit for three-phase AC power: feeding three power phases to respective loads; measuring power drain on the three power phases by the respective loads; based on measuring, detecting an unbalanced power drain across the three power phases due to a relatively light power drain on one or more lightly loaded power phases and a relatively high power drain on one or more heavily loaded power phases; computing an amount of power to be drained from the one or more lightly loaded power phases and to be fed to the one or more heavily loaded power phases to balance the power drain across the three power phases; and transferring the amount of power from the one or more lightly loaded power phases to the one or more heavily loaded power phases to balance the power drain across the three power phases.

A method comprises, at a power balancing circuit for three-phase AC power: feeding three power phases to respective loads; measuring power drain on the three power phases by the respective loads; based on measuring, detecting an unbalanced power drain across the three power phases due to a relatively light power drain on one or more lightly loaded power phases and a relatively high power drain on one or more heavily loaded power phases; computing an amount of power to be drained from the one or more lightly loaded power phases and to be fed to the one or more heavily loaded power phases to balance the power drain across the three power phases; and transferring the amount of power from the one or more lightly loaded power phases to the one or more heavily loaded power phases to balance the power drain across the three power phases.