A control device generates a voltage command value for controlling a current flowing between a three-phase AC power supply and a power converter such that a full voltage representative value representing voltage values of all power storage devices agrees with a DC voltage command value. The control device generates a zero-phase voltage command value for controlling a circulating current flowing in a delta connection such that the voltage values of the power storage devices are balanced among first to third arms. The control device combines the voltage command value and the zero-phase current command value to generate an output voltage command value for controlling an output voltage of each unit converter. The control device removes a control amount of the full voltage representative value from a computation of the zero-phase voltage command value to cause output current control and circulating current control not to interfere with each other.

The present disclosure provides a zero-sequence parameter measurement and ground voltage control method for a resonant ground system based on a virtual ground principle. The method, based on the virtual ground principle, arbitrarily specifies a point K in a phasor plane in which three-phase voltages are located. A virtual ground control method is used to achieve virtual ground of the point K, and an accurate zero-sequence resonant parameter of a zero-sequence network under an action of the excitation {dot over (U)}.sub.KN can be obtained. When a single-phase ground fault occurs, a ground phase is specified as a target working point, and a control method is applied to cause the zero-sequence network to accurately resonate, and a voltage of this phase relative to ground is 0. At this time, both a residual voltage and a residual current of the fault phase are effectively suppressed.

In a power storage system, a three-phase AC wire is connected to a three-phase AC power system. Power storage blocks, each of which includes a power storage module and a power conditioner, are connected in parallel to the three-phase AC wire. A system controller individually controls power storage blocks. The power storage modules each includes: a power storage unit; and a management unit that manages the power storage unit. The power conditioner includes a power converter and a controller. The power converter converts DC power discharged into single-phase AC power and outputs the converted AC power to two lines of the three-phase AC wire, or converts single-phase AC power received from the two lines of the three-phase AC wire into DC power and charges the power storage unit. The controller is connected to the system controller via a communication line and the management unit via a communication line.

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.

A system and method for current balancing from a three-phase AC power source is disclosed. The system includes power supply units, each having inputs coupled to one output of the three phase power source, and a neutral conductor. Multiple loads are each coupled to a DC output of one of the power supply units. Each of the loads include a component having adjustable power consumption. A controller is coupled to each of the power supply units and each of the loads. The controller is operable to compare the power consumption of each of the loads to an average value. The controller adjusts the power consumption of at least one of the loads to balance the power consumption between the loads.

Aspects of the subject disclosure may include, for example, embodiments detecting and correcting load imbalance on power supply phases within a managed scope using a software controlled power switch matrix that is resident in each power distribution unit supplying power in the managed scope. Managed scope could include a plurality of power distribution units supplying a plurality of circuit or equipment loads in a plurality of premises. On each PDU, the software controlled switch matrix maintains and changes physical coupling of power supply phases to circuit and equipment loads. Further embodiments include correcting power supply phase load imbalances through software commands to adjust the coupling of power supply phases to circuit or equipment loads. Embodiments are intended to help power administrators maintain power supply phase load balance effectively in a managed scope. Other embodiments are disclosed.

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.

Some embodiments of the invention provide a method for balancing the power output to each phase of a set of micro-inverters. The method of some embodiments is performed by a gateway, which receives output messages from a plurality of micro-inverters. The gateway identifies the phase of each micro-inverter and calculates the output of the plurality of micro-inverters to each power line of a multi-phase system. The gateway then sends control signals to the micro-inverters to control the output of each micro-inverter to maintain a balanced aggregate power output to each phase of the power grid.

The present application relates to a controller arrangement for controlling an inverter for converting an input power from a power source to a multiphase AC output power provided at a power output of the inverter. The power output is connected to a load and additionally to a power grid. The controller arrangement includes a signal input for receiving a power signal per phase representative of at least one of the power per phase provided to the load or the power per phase provided to the power grid. The controller arrangement is further adapted to control each phase of the multiphase AC output power individually according to the corresponding power signal. The invention further relates to an inverter comprising such a controller arrangement, a power distribution arrangement comprising such an inverter and a controller arrangement to control the inverter and the invention further relates to a method for controlling such an inverter.

The disclosure relates to a power electronics device having at least two inverters and a transformer apparatus having a core arrangement, at least one primary winding and at least one secondary winding that wind around the core arrangement at least in sections.