An energy storage device for a photovoltaic system includes: at least one first energy store which has a first cycle stability; at least one second energy store which has a second cycle stability, the first cycle stability being higher than the second cycle stability; and a control device which is designed to discharge the first energy store in a first operating mode and to discharge the second energy store in a second operating mode.

A method for detecting a voltage disturbance in a utility having a micro-grid. The method transforms current and voltage measurements into first and second voltage values and first and second current values in a stationary reference frame, and transforms the first and second voltage values and the first and second current values to third and fourth voltage values and third and fourth current values in a rotating reference frame, where the third voltage value defines an average magnitude of the three-phase power signals. The method multiplies the third current value by the third voltage value to obtain an instantaneous power value and multiplies the fourth current value by the third voltage value to obtain an instantaneous volt-ampere reactive (VAR) value. The method opens the switch if the VAR value has a magnitude above a predetermined value and a direction indicating the fault is outside of the micro-grid in the network.

A method relating to a device (1) for driving at least one power electric load (2) with the aim of reducing the electric power liable to be consumed or which is actually consumed in a terminal installation (4) of an electrical network including an electrical energy meter behind which the device is connected. A system (12) including such a device and at least one power electric load (2) is also described. Also described is a method for exploiting a plurality of systems (12) within an electrical network as well as the applications of this method for the management of an electrical network including intermittent-production energy sources, within the framework of a service for managing reduction in electrical energy consumption and/or to supplement a service for providing sanitary hot water, and/or heating, and/or cooling, and/or for providing electricity.

A system and method for changing protection settings groups for relays in a micro-grid between a grid-connected settings group and an islanded settings group. The method changes a power source relay from the grid-connected settings group to the islanded settings group before the micro-grid is disconnected from the utility grid, disconnects the micro-grid from the utility grid, and then changes a load relay from the grid-connected settings group to the islanded settings group after the micro-grid is disconnected from the utility grid. The method also changes the load relay from the islanded settings group to the grid-connected settings group before the micro-grid is connected to the utility grid, connects the micro-grid to the utility grid, and then changes the power source relay from the islanded settings group to the grid-connected settings group after the micro-grid is connected to the utility grid.

A method for correcting protection settings in a relay provided in a micro-grid between a grid-connected settings group when the micro-grid is electrically coupled to a utility grid and an islanded settings group when the micro-grid is disconnected from the utility grid. The method determines whether the micro-grid is connected to the utility grid and what settings group the relay is in. The method changes the settings group of the relay to the grid-connected settings group if a time that the micro-grid is connected to the utility grid and the relay is in the islanded settings group exceeds a predetermined time and changes the settings group of the relay to the islanded settings group if the time that the micro-grid is not connected to the utility grid and the relay is in the grid-connected settings group exceeds the predetermined time.

A method for providing power to loads in a micro-grid during a block load event, where the micro-grid includes a rotating generator and a fast-responding energy storage system. The method determines that the micro-grid has been disconnected from the utility grid and then starts the generator to provide electrical power to the loads. The method causes the generator to electrically charge the energy storage system, and electrically couples the loads to the generator while the storage system is being charged. The energy storage system detects that the frequency of the generator is falling as a result of being electrically coupled to the loads, and starts discharging in response to the falling frequency to provide power to the loads to reduce the amount of power that is needed to be supplied to the loads by the generator.

The present disclosure provides a frequency control method for a micro-grid and a control device. The method includes: determining a middle parameter at iteration k; determining a local gradient parameter at iteration k according to the cost increment rate at iteration k, the frequency difference between iterations k and k+1, and communication coefficients; performing a quasi-Newton recursion according to the middle parameter and local gradient parameter to acquire a recursion value; determining the cost increment rate at iteration k+1 according to the recursion value; determining an adjustment value of an active power according to the cost increment rate at iteration k+1; adjusting the active power according to the adjustment value if the adjustment value satisfies a constraint condition and judging whether the difference is smaller than a predetermined threshold; executing k=k+1 if yes and stopping the frequency control if no.

Provided are a supply pipe and a pipe system that may simultaneously accumulate a plurality of thermal energies having different temperatures in a thermal energy network based on bilateral heat trade. The supply pipe is driven by an operation system, supplies a thermal energy to a user or a heat source, and includes an external pipe, at least two internal pipes that are disposed inside the external pipe and accumulate a thermal energy having a predetermined temperature, and a filler that fills the external pipe inside which the at least two internal pipes are disposed, wherein the at least two internal pipes have thermal energies having different temperatures.

A method of managing a microgrid and control system is provided, in which the virtual resistance control gains (in frame) of each respective inverter is dynamically adjusted based on a variable related to the available power from each of a plurality of renewable distributed generators.

The present invention provides a system and a method for switching a line short-circuit fault section in an inverter-based stand-alone microgrid, the system comprising: multiple intelligent switchgears disposed on a line in a stand-alone microgrid so as to control opening or closing of the line; a battery inverter having a built-in current limiter so as to limit a current output therefrom; and an operating system for receiving short-circuit fault information of the line from the multiple intelligent switchgears, determining a fault section, and controlling the battery inverter to limit the output current. The present invention can quickly and accurately switch a line short-circuit fault section occurring in a stand-alone microgrid which does not include separate cutoff equipment such as a recloser.