A solar cell power conversion device is disposed between a solar cell and a distribution system. A storage battery power conversion device is disposed between a storage battery and the distribution system. An effective voltage calculation circuit calculates an effective voltage of an AC voltage in the distribution system. Based on the effective voltage, a second control circuit and a fourth control circuit control active power and reactive power output from a first DC/AC conversion circuit and a second DC/AC conversion circuit, respectively. When a change in the effective voltage is caused by an operation of an SVR provided in the distribution system, the second and fourth control circuits control operations of the first and second DC/AC conversion circuits to suppress a change in the reactive power caused by the change in the effective voltage.

A transformer assembly for electric grids including: an electric transformer including a magnetic core, a first side including one or more first windings enchained with said magnetic core and adapted to be electrically connected to a first grid section and a second side including one or more second windings enchained with said magnetic core and adapted to be electrically connected to a second grid section; a tap changer operatively associated with said electric transformer to vary the number of turns enchained with said magnetic core for said first windings; a control unit to: acquire input data indicative of an electrical connectivity condition of said second grid section with said second windings; determine whether said transformer is in a load condition or in a no-load condition; and, in a no-load condition, command said tap changer to set a maximum available number of turns for said first windings.

A method and system is disclosed for identifying a location of an event in a power distribution network. The method includes receiving voltage and current flowing downstream and upstream of the distribution feeder from at least two distribution-level phasor measurement units (PMUs) installed on a distribution feeder in the power distribution network; calculating changes in forward nodal voltages along the distribution feeder using measurements from at least one PMU of the at least two distribution-level PMUs; calculating changes in backward nodal voltages along the distribution feeder using the measurements from another PMU of the at least two distribution-level PMUs; comparing the calculated changes in the forward nodal voltages to the calculated changes in the backward nodal voltages; and determining the location of the event based on the comparison of the calculated changes of the forward nodal voltages to the calculated changes backward nodal voltages.

A rapid shutdown system and a method for controlling the rapid shutdown system are provided. For each of shutdown devices in the rapid shutdown system, an electrical signal disturbance is applied to a direct current bus connected to the shutdown device at least once within each pre-shutdown period of the shutdown device, by an inverter in the rapid shutdown system operating in a mode of limited power output. Then, the shutdown device samples its input parameter and/or output parameter and determines, based on the sampled input parameter and/or the sampled output parameter, whether the electrical signal disturbance applied to the direct current bus meets a preset condition. The shutdown device switches itself on or remains in an ON state in response to a determination result that the electrical-signal disturbance already meets the preset condition.

The invention relates to wind turbines, particularly to controlling reactive power exchange between a power grid and a wind power plant. The wind power plant has a plurality of wind turbine generators each having a corresponding power converter with a converter controller. Further, the wind power plant has a power plant transformer with an on load tap changer coupled between the wind power plant and the power grid. The power plant controller is regulating the on load tap changer and is generating reactive component setpoints for the wind turbine generators, when determining a need for production of short-term reactive power due to a sudden change in reactive power measured at the point of common coupling.

The invention provides a reactive power optimization system and a method of a power grid based on a double-fish-swarm algorithm. The system includes a power grid state data acquiring module, a reactive power regulating module and a reactive power executing module. The power grid state data acquiring module includes a power grid state data acquiring processor and a relay transmitter. The reactive power regulating module is a control terminal. The reactive power executing module includes generator terminal voltage regulators, transformer tap regulators and reactive power compensation regulators. The method is used for acquiring the initial data to be optimized in the current network; and optimizing the initial data to be optimized in the current network based on a double-fish-swarm algorithm so as to obtain optimal value of control variables in the power grid. According to the method, the distribution network to be optimized can realize reasonable reactive power flow distribution.

A micro inverter, a photovoltaic system and a method for controlling a micro inverter are provided. The micro inverter includes a controller, a primary H-bridge, a transformer, a bi-directional switch arm and a capacitor arm. The controller is configured to: determine a reactive current based on a grid voltage, an equivalent capacitance of an output terminal of the inverter and a grid angle; add the reactive current to a given current to generate an internal phase-shift angle and an external phase-shift angle from a new given current obtained through the addition, where the internal phase-shift angle refers to a phase-shift angle between two arms of the primary H-bridge and the external phase-shift angle refers to a phase-shift angle between the primary H-bridge and the bi-directional switch arm.

A system for an electrical power distribution network receives electricity from one or more distributed energy resources. The system includes a voltage regulation device configured to maintain a voltage in the electrical power distribution network within a range of voltages, the voltage regulation device including a voltage sampling module configured to obtain an indication of a voltage in the electrical power distribution network; and a control system coupled to the voltage regulation device, the control system configured to: determine a metric related to a time rate of change of the voltage in the power distribution network based on at least two samples of the voltage in the electrical power distribution network obtained at different times; and change at least one operating parameter and/or an operating mode of the voltage regulation device based on the determined rate of change of the voltage.

Disclosed are a method and system for determining the installation position of a thyristor controlled phase shifter, a medium and a computing device. The installation position of a thyristor controlled phase shifter can be determined according to the variation of the voltage stability index of a power system before and after the thyristor controlled phase shifter is installed, thus providing technical support for the selection of the installation position of the thyristor controlled phase shifter in a power grid.

A method and a system for controlling an on-load tap changer of a transformer during reverse power flow includes determining a loss ratio factor using voltage and current values for each of a primary side and a secondary side of a transformer. Further, the method comprises determining a relative strength of a first source connected to the primary side and a second source connected to the secondary side of the transformer based on the loss ratio factor. Thereafter, transmitting a control signal to an on-load tap changer of the transformer to regulate voltage on the primary side or on the secondary side of the transformer based on the relative strength of the first source and the second source.