A method is provided for operating a multi-cell power supply that includes multiple series-connected power cells in each of multiple legs. Each power cell includes a bypass device that may be used to selectively bypass and de-bypass the power cell. After a first power cell faults and is bypassed as a result of the fault, the method includes de-bypassing the first power cell without stopping the multi-cell power supply if the first power cell fault was caused by a predetermined operating condition. Numerous other aspects are provided.

A switching system for switching between phases in a multi-phase power distribution system includes a switch for selectively connecting a lateral line to feeder conductors of different phases in a multi-phase power distribution system. Feeder terminals of the switch are configured to connect to feeder conductors of the multi-phase power distribution system. At least one output terminal of the switch is configured to connect to the lateral line. The feeder terminals are spaced about the body of the switch. A shaft and a rotatable contact member extending radially from the shaft are configured for rotating within the switch body to selectively connect the at least one output terminal to any one or more of the feeder terminals. At least one controller operates the switch to selectively change connection of the lateral line between the feeder conductors.

A method is performed in a control device for controlling a power compensation arrangement including a voltage source converter and one or more power compensation branches, each power compensation branch including a thyristor controlled reactor, a thyristor switched reactor or a thyristor controlled capacitor. The voltage source converter and the one or more power compensation branches are connected to a same busbar. The method includes: detecting a request in an electrical power system to which the power compensation arrangement is connected; determining, based on the request, a need for reactive power supply to the electrical power system; providing reactive power by means of the voltage source converter and/or by one or more of the power compensation branches; and compensating, by means of the voltage source converter, any disturbances caused by the power compensation branches when providing the reactive power to the electrical power system. Corresponding devices are also disclosed.

This disclosure relates to a photovoltaic energy storage and power system and a three-phase power control method, apparatus and device for load(s). The three-phase power control method for load(s) in a photovoltaic energy storage and power system includes obtaining a drawing or feeding power of a grid, an charging or discharging power of energy storage, and a photovoltaic generation power; determining a generation power of an electric power system based on the drawing or feeding power of the grid, the charging or discharging power of the energy storage, and the photovoltaic generation power; and distributing the generation power of the electric power system evenly to load(s) of each phase to achieve three-phase dynamic balancing.

A control apparatus in a static VAR compensator (SVC) system includes a plurality of current supply units for supplying phase currents configuring three-phase current of a power system, a plurality of current sensors for measuring the phase currents, and a controller for determining whether unbalance occurs in the three-phase current based on the phase currents, calculating an error corresponding to the unbalance according to the phase currents if unbalance occurs, and individually controlling at least one of the plurality of current supply units so as to compensate for the error.

A controller controls a first switch, a second switch, a third switch, a fourth switch, a fifth switch and a sixth switch, so that an alternating current electric power is fed to an alternating current electric grid. Moreover, the controller firstly turns on a first route including the first switch and the second switch, and then the controller turns on a second route including the third switch and the fourth switch if the second route meets a first specific condition, and then the controller turns on a third route including the fifth switch and the sixth switch if the third route meets a second specific condition.

A power control system includes a multi-phase power source, an ungrounded multi-phase load, a plurality of power switching circuits and a plurality of zero-crossing circuits. The multi-phase power source includes a plurality of phase power outputs. The plurality of power switching circuits are each connected to provide power from one of the plurality of phase power outputs to the ungrounded multiphase load. The plurality of zero-crossing circuits are connected to provide control signals to the plurality of power switching circuits. Each of the plurality of zero-crossing circuits are connected between one of the plurality of power phase outputs and an ungrounded reference.

A system includes first and second pluralities of single phase AC/DC power supplies each having an input for coupling to first and second phase voltages, respectively, in a polyphase power distribution system. The outputs of the power supplies are electrically connected in parallel for supplying DC current to a load at a substantially constant voltage. The system further includes a controller coupled to at least the first plurality of power supplies and configured to increase the DC current supplied to the load by at least one of the first plurality of power supplies in response to another one of the first plurality of power supplies shutting down. Various other systems, power supplies, controllers and methods are also disclosed.

A power control system includes a multi-phase power source, an ungrounded multi-phase load, a plurality of power switching circuits and a plurality of zero-crossing circuits. The multi-phase power source includes a plurality of phase power outputs. The plurality of power switching circuits are each connected to provide power from one of the plurality of phase power outputs to the ungrounded multiphase load. The plurality of zero-crossing circuits are connected to provide control signals to the plurality of power switching circuits. Each of the plurality of zero-crossing circuits are connected between one of the plurality of power phase outputs and an ungrounded reference.

A method for operating a power generation system coupled to a power grid during a grid unbalance event, a method for determining an injection current to be supplied into a power grid by a power generation system, and a method for addressing an asymmetric grid fault in a power grid connected to a power generation system are provided. The methods may be carried out based on a reactive or an active power/current priority.