Apparatus for storing power and method of controlling the same
Provided are a power storage apparatus and a method of controlling the power storage apparatus. The power storage apparatus stores power supplied from a power generation system or a power grid. The power storage apparatus supplies stored power to a load during an electric failure, and supplies stored power to the power grid. The power storage apparatus includes at least one battery cell, a battery management unit coupled to the battery cell, a bi-directional converter coupled to the battery management unit, a bi-directional inverter coupled between the bi-directional converter and the power grid, and a central controller controlling the operations of the bi-directional converter, the bi-directional inverter, and the battery management unit. An uninterruptible power supply (UPS) function may be performed to stabilize the power storage system including the power storage apparatus.
1. A power storage apparatus comprising:
a bi-directional inverter connected between a first node and a second node connected to a power grid and a load, the bi-directional inverter converting a direct current (DC) voltage supplied from the first node to an alternating current (AC) voltage and outputting the AC voltage to the second node, the bi-directional inverter converting an AC voltage supplied from the power grid to a DC voltage and outputting the DC voltage to the first node;
at least one battery cell;
a battery management unit for detecting a remaining amount of power in the at least one battery cell and controlling charging/discharging of the at least one battery cell;
a bi-directional converter connected between the battery management unit and the first node, the bi-directional converter converting a DC voltage supplied from the at least one battery cell to another DC voltage and outputting the another DC voltage to the bi-directional inverter via the first node, the bi-directional converter converting a DC voltage supplied from the bi-directional inverter to another DC voltage and outputting the another DC voltage to the at least one battery cell; and
a central controller performing a control operation for charging the at least one battery cell with power supplied from the power grid, the central controller controlling the battery management unit, the bi-directional converter, and the bi-directional inverter so as to supply power stored in the at least one battery cell to the power grid, the central controller blocking power supply from the at least one battery cell to the power grid when the remaining amount of power of the at least one battery cell is lower than a reference level.
2. The power storage apparatus of claim 1 , wherein the central controller controls the battery management unit, the bi-directional converter, and the bi-directional inverter so as to supply the power from the at least one battery cell to the load when the power grid is in an abnormal state.
3. The power storage apparatus of claim 1 , wherein the central controller controls the battery management unit, the bi-directional converter, and the bi-directional inverter so as to supply the power stored in the at least one battery cell to the load when power consumption of the load is equal to or greater than a reference power consumption level.
4. The power storage apparatus of claim 3 , wherein the central controller controls the battery management unit, the bi-directional converter, and the bi-directional inverter so as not to supply the power stored in the at least one battery cell to the load even if the power consumption of the load is equal to or greater than the reference power consumption level, when the remaining power of the at least one battery cell is lower than the reference level.
5. The power storage apparatus of claim 1 , further comprising a power conversion unit for converting power supplied from a power generation system into a DC voltage and outputting the DC voltage to the bi-directional converter via the first node, the bi-directional converter converting the DC voltage from the power conversion unit to another DC voltage and outputting the another DC voltage to the at least one battery cell.
6. The power storage apparatus of claim 5 , wherein the power generation system includes a solar battery, and the power conversion unit controls a level of generated power so as to track a maximum power supply voltage from the solar battery by using a maximum power point tracker (MPPT) algorithm.
7. The power storage apparatus of claim 1 , further comprising a voltage stabilization unit connected to the first node for stabilizing a voltage level at the first node.
8. The power storage apparatus of claim 1 , further comprising:
a first switch connected between the bi-directional inverter and the second node; and
a second switch connected between the second node and the power grid, wherein the central controller turns the first switch and the second switch on when the power grid is in the normal state, and turns the first switch on and turns the second switch off when the power grid is in the abnormal state.