Power storage apparatus, method of operating the same, and power storage system
A power storage system and method are disclosed. The system is connected to a load, a power grid, and a power generation system. When the grid is in an abnormal state, a battery is simultaneously charged with power from the power generation system and used to supply power to the load.
1. A power storage apparatus, comprising:
a power conversion unit connected between a power generation system and a first node, wherein the power conversion unit is configured to convert power generated by the power generation system into a DC voltage for the first node;
a battery management system (BMS);
a bi-directional converter connected between the BMS and the first node, wherein the bi-directional converter is configured to convert the DC voltage of the first node to a DC voltage for the BMS and to convert the DC voltage of the BMS to the DC voltage of the first node;
a bi-directional inverter connected between the first node and a second node, wherein the bi-directional inverter is configured to invert the DC voltage of the first node into an AC voltage for a load or for a power grid and to convert an AC voltage from the power grid into the DC voltage of the first node;
a grid connector for connecting the power grid to the second node;
a battery comprising a plurality of battery units configured to be charged by power from at least one of the power generation system and the grid, and to be discharged to supply power to the load; and
an integrated controller configured to determine a state of the grid, and if the grid is in an abnormal state to control the grid connector to disconnect the power grid from the second node, and the integrated controller is configured to control the power conversion unit, the bi-directional converter, the bi-directional inverter, the grid connector, and the battery, wherein if the grid is in an abnormal state the integrated controller monitors a charging and discharging status of the battery and controls the battery to supply power to the load and to be simultaneously charged with power generated by the power generation system.
2. The power storage apparatus of claim 1 , wherein the battery comprises:
a plurality of battery units connected in parallel with each other, wherein the battery units are configured to be individually charged and discharged; and
a plurality of switching elements, each switching element configured to connect one of the plurality of battery units to a charging path or to a discharging path.
3. The power storage apparatus of claim 2 , wherein, if in the abnormal grid state, the battery units which are connected to the charging path, are charged with power supplied from the power generation system, and the battery units which are connected to the discharging path are discharged by supplying power to the load.
4. The power storage apparatus of claim 2 , wherein the integrated controller comprises:
a power grid controller configured to detect the abnormal state, to control the grid connector, and to disconnect the power grid from the second node;
a battery monitoring unit configured to monitor the charging and discharging status of the plurality of battery units and to determine whether to connect each of the plurality of battery units to the charging path or to the discharging path according to the charging and discharging status of each battery unit; and
a switching controller configured to control the switching element of each battery unit according to the determination of the battery monitoring unit.
5. The power storage apparatus of claim 4 , wherein the battery monitoring unit is configured to determine that the battery units in a completely charged state are to be connected to the discharging path and that the battery units in an incomplete charging state are to be connected to the charging path.
6. The power storage apparatus of claim 4 , wherein the integrated controller further comprises:
a charging controller configured to control the power conversion unit and the bi-directional converter so as to charge the plurality of battery units with power generated by the power generation system; and
a discharging controller configured to control the bi-directional converter and the bi-directional inverter so as to supply power stored in the plurality of battery units to the load.
7. The power storage apparatus of claim 1 , wherein the power generation system comprises a new or renewable energy source.
8. The power storage apparatus of claim 1 , wherein the power generation system comprises at least one of: a solar power generation system, a wind power generation system, a ground heat power generation system, a water power generation system, an ocean power generation system, and power generation system that uses a fuel battery, hydrogen, liquefied coal gas or medium quality residual oil gas.
9. The power storage apparatus of claim 1 , further comprising a DC link capacitor connected to the first node.
10. The power storage apparatus of claim 1 , wherein the BMS is connected between the battery and the bi-directional converter and is configured to manage the battery.
11. A method of operating a power storage apparatus connected to a power generation system, a power grid, and to a load, the apparatus comprising a power conversion unit, a bi-directional converter, a bi-directional inverter, a grid connector, a battery comprising a plurality of battery units, and an integrated controller for controlling the power conversion unit, the bi-directional converter, the bi-directional inverter, the grid connector, and the battery, the method comprising:
disconnecting the power grid from the power storage apparatus as a result of the grid being in an abnormal state;
monitoring the charging and discharging status of each of the plurality of battery units; and
according to the charging and discharging status of each of the plurality of battery units discharging certain battery units to supply power to the load, and simultaneously charging other battery units with power generated by the power generation system.
12. The method of claim 11 , further comprising:
connecting battery units that are in a complete charging state to a discharging path; and
connecting battery units that are in an incomplete charging state to a charging path.
13. The method of claim 12 , wherein connecting battery units to the discharging path supplies power from the battery units connected to the discharging path to the load.
14. The method of claim 12 , wherein connecting battery units to the charging path charges the battery units connected to the charging path with power generated by the power generation system.