Patent ID: 8362643

Claim:
A battery-based grid energy storage for balancing the load of a power grid comprises: a battery array; a bi-directional inverter system configured to charge the battery array using power from the power grid, or conversely, to transmit power from the battery array to the power grid; a monitor system configured to detect the load, frequency and phase of the power grid, and control the bi-directional inverter system to charge the battery array using power from the power grid, or conversely, transmit power from the battery array to the power grid in accordance with the frequency and phase of the power grid; and a transformer configured to transform high voltage electric power of the power grid into low voltage electric power, wherein the low voltage electric power is supplied to the bi-directional inverter system to charge the battery array and transform low voltage electric power of the bi-directional inverter system into high voltage electric power, wherein the high voltage electric power is transmitted to the power grid, wherein: during a predefined battery discharging time period, the monitor system is configured to control the bi-directional inverter system to transmit power from the battery array to the power grid if the currently-detected load of the power grid is above a first predefined threshold of the power grid capacity, and during a predefined battery charging time period, the monitor system is configured to control the bi-directional inverter system to transmit power from the power grid to the battery array if the currently-detected load of the power grid is below a second predefined threshold of the power grid capacity.