Power distribution device and method using droop control

A power distribution method in a converter configured to perform DC-DC conversion between a battery among a plurality of batteries and a power conversion system (PCS), the method comprising:

• receiving information on a droop curve for controlling an output of the converter from a controller configured to manage states of the plurality of batteries and storing the received information on a droop curve;
• detecting a voltage change at a DC link between the PCS and the converter;
• and
• controlling an output of the converter according to a detected DC link voltage and the droop curve to discharge or charge the battery among the plurality of batteries.

A converter configured to perform DC-DC conversion between a battery and a power conversion system (PCS), the converter comprising:

• a memory configured to store information on a droop curve for controlling an output of the converter;
• and
• a processor configured to:
• detect a voltage change at a DC link between the PCS and the converter;
• and
• control an output of the converter according to a detected DC link voltage and the stored information on the droop curve.

An energy storage system comprising:

• a plurality of battery racks;
• a plurality of converters each configured to perform DC-DC conversion for a corresponding one of the plurality of battery racks;
• a power conversion system connected between the plurality of converters and a power grid;
• and
• a battery section controller configured to determine droop curves for controlling outputs of the converters according to states of the battery racks, respectively,
• wherein each converter among the plurality of converters is configured to:
• receive and store information on a corresponding one of the droop curves determined by the battery section controller,
• detect a voltage change in a DC link between the power conversion system and the converter, the voltage change being caused by a start of a charging or a discharging operation, and
• control an output of the converter based on a detected DC link voltage and the corresponding droop curve.