According to some embodiments, two or more subsea motors are run simultaneously from a common topside frequency converter and a single set of three-phase cores within an umbilical cable. The subsea distribution system, which may include a subsea transformer distributes the power to the electrical motors. Current sensor and measuring electronics are used to measure current on one or more of the phases used to drive each motor. Measurement data is transmitted to the surface where an analysis system is used to detect possible load imbalance conditions between the motors.

In the present invention, a system and a method for unbalance adjustment for inverter split-phase controlling and distribution transformer current are provided, in which the system for unbalance adjustment for inverter split-phase controlling and distribution transformer current includes a distributed power supply and a three-phase full-bridge inverter. The three-phase full-bridge inverter is connected to the distributed power supply, and the three-phase full-bridge inverter is connected to a three-phase line through a three-phase reactor. When an unbalance degree corresponding to the three-phase line is greater than a preset starting value, a three-phase compensation current reference value is obtained according to the present front-end three-phase load current, back-end three-phase load current and capacitor voltage control component, such that the three-phase full-bridge inverter can output the three-phase compensation current based on the three-phase compensation current reference value. Therefore, in embodiments of the present invention, the three-phase full-bridge inverter can use the output power of the distributed power supply to output the compensation current required for each phase of the three-phase line, realizing the unbalanced control in the three-phase current of the distribution transformer, so that the three-phase current of the distribution transformer reaches balance.

A polyphase power dispatching system and a polyphase power dispatching method are provided. The polyphase power dispatching system includes an electric meter, a single-phase electricity storage module, a switch and a control circuit. The electric meter can measure transmission statuses of power transmission lines of a polyphase power line group. The common terminal of the switch is connected to the single-phase electricity storage module. The selection terminals of the switch are connected to the power transmission lines in a one-to-one manner. The control circuit is connected to the electric meter and the switch. The control circuit can correspondingly control the switch based on the transmission status of each power transmission line, so that the switch selectively connects the single-phase electricity storage module to one of the power transmission lines.

A method includes determining whether transformer phases should be permuted. The method includes, responsive to a determination that the transformer phases should be permuted, permuting the transformer phases, based on historical aging information of transformer input phases, to cause transformer input phases with higher ages to be connected to transformer output phases with lower output loads and transformer input phases with lower ages to be connected to transformer output phases with higher output loads. Multiple apparatus and program products are also disclosed.

A method for controlling an uninterruptible power supply (UPS) having a polyphase power input and an input power circuit coupled to the polyphase power input includes determining to reduce a load on a first phase of the polyphase power input, and in response thereto, controlling the input power circuit to reduce a first input current drawn from the first phase by a first amount and increase a second input current drawn from a second phase of the polyphase power input by a second amount. The UPS may determine to reduce the load on the first phase in response to a request from a smart grid to reduce the load on the first phase or in response to a local determination to reduce the load on the first phase.

An electrical energy transmission system has a three-phase electric current power source generating a three-phase current including three currents of different phases, a three-phase current converting device which converts at least some of the currents, a single-wire electric current transmission line configured to transmit the converted currents to a consumer, and a balancing device configured to balance the electric currents in the three-phase current source and providing thereby a stable operation of the three-phase current power source.

An AC power transformer includes primary and secondary windings for at least a first AC phase and a second AC phase, and a core for said at least first and second phases. The transformer further includes a control unit for transferring power from the first phase to the second phase via magnetic coupling in the core such that the sum of the phase vectors of all of the at least first and second phases is substantially zero.

Power delivery systems and methods described herein conductively couple several input lines with a cable that conducts a multi-phase electric current. The input lines separately conduct different phases of the electric current. Output lines are conductively coupled with plural machines, and separately conduct the different phases of the electric current. Plural switching devices are conductively coupled with the input lines and with the output lines, and are used to control the switching devices in order to conduct the different phases of the electric current to the machines. A first set of the switching devices is closed to separately conduct the different phases of the electric current to a first machine of the machines. A different, second set of the switching devices is separately closed to separately conduct the different phases of the electric current to a different, second machine of the machines.

A single phase redundant power supply system may include a first power supply having an input coupled to a first phase voltage in a polyphase power distribution system and an output coupled to a load for supplying an amount of DC power to the load, and a second power supply having an input for coupling to a second phase voltage in the polyphase power distribution system and an output coupled to the load for supplying an amount of DC power to the load. At least the first power supply is configured to reduce phase current imbalances in the polyphase power distribution system by adjusting the amount of DC power supplied to the load by the first power supply and the amount of DC power supplied to the load by the second power supply.

The present disclosure is directed to a system and method for controlling an electrical power system connected to a power grid. The method includes determining, via a negative sequence regulator programmed in a controller of the electrical power system, a negative sequence component of at least one electrical condition of the electrical power system. Further, the method includes determining a desired current response based on the negative sequence component of the at least one electrical condition of the electrical power system. Thus, the method also includes determining a control command for the power converter as a function of the desired current response so as to achieve a desired relationship between a voltage condition in the power grid and the negative sequence component of the electrical condition of the electrical power system.