A power system can include a first tap changer for a first regulated transformer, where the first tap changer has a plurality of first positions. The power system can also include a second tap changer for a second regulated transformer, where the second tap changer has a plurality of second positions. The power system can further include at least one first instrument transformer coupled to the first regulated transformer. The power system can also include at least one second instrument transformer coupled to the second regulated transformer. The power system can further include a controller coupled to the at least one first instrument transformer and the at least one second instrument transformer, where the controller adjusts the first tap changer to a first adjusted position among the first positions based on the first measurements of the first regulated transformer and the second measurements of the second regulated transformer.

An uninterruptible power supply system (UPS) includes an interconnect circuit configured to receive three-phase AC input power from an AC power source and a plurality of UPS subsystems each coupled to the interconnect circuit. A first UPS subsystem includes first and second single-phase AC-to-DC converters. At least one second UPS subsystem includes third and fourth single-phase AC-to-DC converters. In a first mode of operation, the interconnect circuit is configured to conduct at least one phase of the AC input power to the first UPS subsystem and at least one phase of the AC input power to the second UPS subsystem, and, in a second mode of operation, to disconnect the AC input power from the first UPS subsystem and to conduct at least one phase of the AC input power to the second UPS subsystem.

An arrangement for connecting a railway power supply for a railway track to a three-phase supply network. The arrangement has a three-phase AC transformer and a balancing device for a uniform electric load of the three phases of the three-phase supply network. The three-phase AC transformer is configured for connecting to the three-phase supply network on the primary side and is connected to the balancing device on the secondary side. The three-phase AC transformer is configured for connecting to a railway power supply which has an autotransformer system with two contact lines and two conductors that are carried along the railway track in an insulated manner.

Systems and methods for controlling power flow to and from an energy storage system are provided. One energy storage system includes an energy storage device and a bidirectional inverter configured to control a flow of power into or out of the energy storage device via a plurality of phases. The energy storage system further includes a controller configured to control the bidirectional inverter based on a load condition on one or more phases. The controller is configured to control the bidirectional inverter to store power generated by a generator set in the energy storage device and transmit power from the energy storage device to a load driven by the generator set in response to detecting a load imbalance between the phases.

Aspects extend to methods, systems, and computer program products for balancing input phases across server rack power supplies. A rack manager can monitor individual Alternating Current (AC) phase currents at the rack level. The rack manager knows (or can at least determine) which power supplies are connected to which phase. The rack manager can micro adjust individual PSU output voltages to balance current phases at the rack level. Balancing can occur in response to changed server workloads, hot-unplug of one or more servers, etc. When there is one PSU per server, phase balancing can be accomplished by connecting outputs of power supplies together via busbar or wire. Output voltages of individual power supplies can be adjusted to achieve better phase balancing. Phase imbalance can be corrected by a bus bar or wire carrying enough load to correct phase imbalance.

Provided are an apparatus and method for load-balancing of a three-phase electric power distribution system having a multi-phase feeder, including obtaining topology information of the feeder identifying supply points for customer loads and feeder sections between the supply points, obtaining customer information that includes peak customer load at each of the points between each of the feeder sections, performing a phase balancing analysis, and recommending phase assignment at the customer load supply points.

Discussed are an energy storage device and an energy storage system including the energy storage device. The energy storage device includes at least one battery pack, a power conversion unit to convert, into DC power, AC power from a first phase from among three phases of an internal power network in a charging mode of the energy storage device, and to convert the DC power stored in the at least one battery pack into the AC power in a discharging mode of the energy storage device, a communication module to exchange data with an external energy storage device, and a controller to control the power conversion unit.

A system and a method for parallel power supply control for auxiliary converters of a motor train unit in the presence of interconnecting lines. The system comprises multiple three-phase inverter modules. The multiple three-phase inverter modules are in parallel connection with each other. Any two-phase circuit of a three-phase inverter module is separately in parallel connection with a corresponding two-phase circuit of a three-phase inverter module adjacent to the three-phase inverter module by using a connecting line module. The connecting line module is connected to a control system. The three-phase inverter modules are also connected to the control system. The three-phase lines of the three-phase inverter modules are all provided with switches. Less interconnecting lines are used, and any two phases of the three-phase inverter modules are separately in parallel connection, and therefore, stable power supply is achieved by balancing currents of any two phases of the three-phase circuits, and the system reliability is improved.

A converter system and inverter system are disclosed with individual real and reactive power control for each phase of a poly-phase system. The converter system includes a controller, bidirectional single-phase inverters with AC sides coupled to an AC line filter and DC sides connected in parallel to a link capacitor coupled to DC/DC converters. Each inverter handles a separate AC phase. The controller controls the inverters and DC/DC converters so the current amplitude of each AC phase is independent, and the phase difference of each AC phase is independent. The inverters can be galvanically isolated between the DC and AC sides. The inverters can be non-isolated inverters having line and neutral connectors coupled to an isolated transformer winding, and the output windings of the transformer can be wired in a Wye configuration. The inverters can have local controllers.

The present invention relates to a solid testing platform and method for function testing of an intelligent phase-change switch. The testing platform includes a primary controller, a first module, a second module, a capacitor C, an intelligent phase-change switch, and a transformer. The primary controller is respectively connected to the first module and the second module, and is configured to control the operation of the first module and the second module. The first module and the second module are connected in parallel to the capacitor C. the first module is configured to feed back excess energy of the capacitor C to a distribution network. The second module is configured to control magnitude and direction of a current that flows through the intelligent phase-change switch. The capacitor C is configured to perform energy support, filtering, and smoothing. According to the present invention, not only all unbalanced operation conditions can be simulated, but also simulated power is equitably fed back to a power grid by using the testing platform, to achieve a test in a state of no power loss, without affecting a main power grid.