Control of multiple energy storages in a microgrid

A network controller for an electrical microgrid comprising a plurality of energy storages, each energy storage being associated with a respective storage controller, the network controller comprising:

• processing circuitry;
• and
• a storage storing instructions executable by said processing circuitry, wherein the instructions are configured to cause the network controller to:
• receive information about a measurement, comprising a measurement of a voltage and a frequency made at a remote location within the microgrid, wherein the remote location is at a Point of Common Coupling, PCC, of the microgrid with an AC grid or at a location where a distributed generator, DG, is operatively connected to the microgrid;
• obtain respective participation factors in respect of the remote location for each of a first energy storage and a second energy storage of the plurality of energy storages, wherein a first participation factor for the first energy storage quantifies a deviation of the frequency measured at the remote location in response to active power injection from the first energy storage, and a second participation factor for the second energy storage quantifies a deviation of the voltage measured at the remote location in response to reactive power injection from the second energy storage, wherein the remote location is different from a location of the first energy storage and a location of the second energy storage;
• obtain respective states of charge of each of said first energy storage and second energy storage;
• and
• calculate respective reference values for each of the first energy storage and the second energy storage;
• and
• send the respective reference values to the respective storage controllers associated with the first energy storage and the second energy storage,
• wherein the calculating the respective reference values comprises calculating the respective reference values based on the obtained respective participation factors and the obtained respective states of charge.

A method of operating a microgrid comprising:

• receiving an indication that the microgrid is islanded from an AC grid via a circuit breaker within the microgrid;
• and
• in response to receiving the indication that the microgrid is islanded:
• instructing a first storage controller associated with a first energy storage coupled to the microgrid to operate in a grid forming mode, and
• assigning a second storage controller associated with a second energy storage coupled to the microgrid to operate in a grid following mode;
• obtaining a first state of charge of the first energy storage, and
• obtaining a first participation factor of the first energy storage that quantifies a deviation of a frequency measured at a remote location within the microgrid in response to active power injection from the first energy storage, calculating a first reference value based on the first participation factor and the first state of charge of the first energy storage, and sending the calculated first reference value to the first storage controller, wherein the remote location is at the circuit breaker or at a distributed generator operatively coupled to the microgrid;
• and
• obtaining a second state of charge of the second energy storage, and obtaining a second participation factor of the second energy storage that quantifies a deviation of a voltage measured at the remote location in response to reactive power injection from the second energy storage, calculating a second reference value based on the second participation factor and the second state of charge of the second energy storage, and sending the calculated second reference value to the second storage controller, wherein the remote location is different from a location of the first energy storage and a location of the second energy storage.