Provided is a power converter capable of reducing cross current. The power converter 1 includes a phase controller 20 that calculate a phase angle reference value θm based on a difference between a commanded active power reference value Pe and an output active power P supplied to a distribution line 5, a voltage controller 10 that calculates a voltage reference values Vu, Vv, and Vw based on the phase angle reference value θm calculated by the phase controller 20, and a power conversion unit 52 that converts, based on the voltage reference values Vu, Vv, and Vw calculated by the voltage controller 10, an electric power supplied from a power supply source 60 into AC power and outputs it to the distribution line 5.

An energy storage system includes a plurality of bidirectional power converters and a plurality of windings. The plurality of windings shares a magnetic core. A controller transfers energy of a target battery to the magnetic core using a target bidirectional power converter and a target winding at a same time. A voltage of the target battery is greater than those of some or all batteries other than the target battery. As the battery is charged and discharged, the voltage of the battery changes, and the controller only needs to find a new target battery to continue discharging until voltages of all the batteries are equalized, for example, voltage differences between all the batteries are all within a preset voltage range.

An AC-AC converter can include a stack of four switches. An input of the converter can be coupled across the stack of four switches, and an output of the converter can be taken from first terminal coupled to a connection point of first and second switches of the stack and a second terminal coupled to a connection point of third and fourth switches of the stack. The converter can further include a controller that operates the switches such that during a positive half cycle of an AC input voltage, the first and second switches are operated with an alternating 50% duty cycle and the third and fourth switches are constantly on, and during the negative half cycle of the AC input voltage, the third and fourth switches are operated with an alternating 50% duty cycle and the first and second switches are constantly on.

A device includes at least one isolating transformer. An input is coupled to the at least one isolating transformer and configured to receive input from an energy source. At least one power switch is coupled to the isolating transformer. A diode is coupled to the at least one isolating transformer. An energy storage medium is coupled to the diode. An inverter includes one or more inverter switches, an inverter input, and an inverter output. The inverter input is coupled to the diode and the energy storage medium. The inverter output is configured to be coupled to the power network, and the inverter is configured to create AC power for distribution to the power network. A controller is configured to modulate the at least one power switch to control power flow from the input and to modulate the state of the inverter switches to control power flow to the power network.

A battery monitoring device including a housing configured to be attached to a battery, at least one memory element included in the housing, the at least one memory element being configured to store data corresponding to the battery, and a device controller included in the housing, the device controller being coupled to the at least one memory element and configured to communicate over a first communication interface with an external controller.

An electric drive system includes at least one electric drive unit. The at least one electric drive unit includes an electric motor and inverters. The inverters are each supplied with DC voltage via a high-voltage bus. The electric drive system also includes a main battery system that has a plurality of battery modules that supply DC voltage to each of the high-voltage buses. The electric device system includes a plurality of reserve batteries. A separate reserve battery of the plurality of reserve batteries is provided for each high-voltage bus. The drive system is configured to make a change to the supply of DC voltage when a corresponding control signal is present for each of the high-voltage buses. A change is made from a supply of DC voltage of the battery module of the main battery system that is assigned to the high-voltage bus to a supply of DC voltage of the reserve battery assigned to the high-voltage bus. A method for supplying DC voltage of a reserve battery to a high-voltage bus is also provided.

An uninterruptible power supply (UPS) system with stranded power recovery has a plurality of UPS modules with one or more of the UPS modules usable to provide stranded power to a recovered power bus. When a UPS module is used to provide stranded power to the recovered power bus, the AC/AC converter associated with that UPS module provides AC power that is synchronized with AC power being provided to the recovered power bus by each of the other AC/AC converters that are providing AC power. In this manner all of the AC/AC converters that are providing AC power to the recovered power bus have the same voltage, the same frequency, and are in phase.

A power system including an input configured to receive input AC power, a DC output configured to provide output DC power to a load, an AC output configured to provide output AC power to the load, an AC/DC converter coupled to the input and configured to convert the input AC power into DC power, a DC bus, and a controller configured to monitor a current demand at the DC output relative to a demand threshold, operate, in response to a determination that the current demand at the DC output is below the demand threshold, the power system in a first mode of operation by enabling the AC/DC converter to provide DC power to the DC bus, and operate, in response to a determination that the current demand at the DC output is above the demand threshold, the power system in a second mode of operation by disabling the AC/DC converter.

An apparatus and method for parameter comprehensive monitoring and troubleshooting of power transformation and distribution are disclosed. The apparatus includes a data acquisition unit, an on-site CPU, a main CPU, an operation and maintenance control center, a UPS and an energy storage breaking mechanism. Each on-site CPU compares the relevant state values of equipment line collected by a data acquisition unit with a threshold set by fiber Bragg grating sensor nodes and sums up to a main CPU. The main CPU stores and display the relevant state values through a display screen. The node represents each distribution point. A link represents a data transmission path. An attached table displays all state parameters. A working state of the distribution equipment is determined according to a color of the node and the link.

A method for controlling a wind farm, which is operated by means of a wind farm control unit and comprises a multiplicity of wind power installations having wind power installation controllers and being connected to one another via a common wind farm grid, which is connected to an electrical power supply grid of a grid operator by means of a wind farm transformer, comprising the following steps: reception of at least one fault bit at the wind farm control unit, in particular at least one fault bit of the grid operator, deactivation of all external setpoint value specifications at the wind farm control unit apart from those of the grid operator after reception of the fault bit, activation of a closed-loop fault case control implemented in the wind farm control unit after successful deactivation of all external setpoint value specifications apart from those of the grid operator.