Abstract:
A method and system for controlling electrical power in a micro-grid, especially during islanding when the micro-grid is disconnected from a main grid is described. A potential load shedding for islanding is determined when the micro grid is connected to the main grid. The potential load shedding is performed when a grid switch that connects the micro-grid to a main grid opens. A frequency based load shedding and a frequency based control of power injections to the micro grid may also be performed. The frequency based load shedding is performed with a faster response than the power injection control during islanding. The frequency based power injection control is performed with a faster response than the frequency based load shedding when the micro grid is connected to the main grid. A load shedding controller, an energy storage controller and methods performed by the load shedding controller, and the energy storage controller, respectively, is also provided.
Abstract:
A microgrid connecting at least one distributed electricity generator includes a first switch configured for, in a closed position, connecting the microgrid to a first network line at a first point of common coupling (PCC) and for, in an open position, disconnecting the microgrid from the first network line at the first PCC; a second switch configured for, in a closed position, connecting the microgrid to a second network line at a second PCC, and for, in an open position, disconnecting the microgrid from the second network line at the second PCC; and a control unit configured for, when an islanding event has been detected when the second switch is in its closed position and the first switch is in its open position, acting to close the first switch, bringing it to its closed position.
Abstract:
A distributed method is provided for controlling electrical power in a microgrid, wherein a plurality of distributed generators supply electrical power to the microgrid, and each of the distributed generators is connected to a controller for controlling the real and reactive output power from the distributed generator. The method includes the steps of measuring, for each of the distributed generators, a voltage level at a measuring point associated with that distributed generator and forwarding the measured voltage level to the controller connected to that distributed generator; determining, for each of the controllers, a parameter value related to the received measured voltage level and/or related to a reactive current injection capacity of the distributed generator connected to that controller; communicating, from each of the controllers, its determined parameter value to each other ones of the controllers; determining a sequential order in which the controllers are to control the distributed generators to inject reactive power into the microgrid based on the communicated parameter values; and controlling the distributed generators to inject reactive power into the microgrid by means of the controllers in the determined sequential order.