Power grid systems comprising energy storage system configured to switch between current source mode and voltage source mode on grid connection and methods for managing the same
The present disclosure relates to a power grid system and method of managing the same. According to the present invention, a power grid system is provided. The power grid system is adapted to supply electric power to at least one load unit, and the power grid system comprises a bus, a switching module, and an energy storage system coupled to the bus. The at least one load unit is coupled to the bus. The switching module comprises a switching device. The switching device is connected between the bus and a main grid. The energy storage system is configured to operate in a current source mode and a voltage source mode, and it is configured to receive a tripped signal from the switching module. The energy storage system is configured to switch to the voltage source mode when the energy storage system receives the tripped signal.
1 . A power grid system adapted to supply electric power to at least one load unit, the power grid system comprising:
a bus, the at least one load unit coupled to the bus;
a switching module comprising a switching device and an intelligent electronic device (IED) coupled to the switching device, the IED configured to monitor electrical characteristics of power flowing through the switching device to determine a fault is occurring and trip the switching device in response, the switching device connected between the bus and a main grid and configured to output a tripped signal when the switching device is tripped, wherein the tripped signal is a feedback signal indicating a status of the switching device;
an energy storage system coupled to the bus, the energy storage system comprising a plurality of storage cells and configured to supply power electricity to the at least one load unit, the energy storage system configured to operate in a current source mode and a voltage source mode, and the energy storage system comprising a receiver card to receive the tripped signal from the switching module; and
wherein the energy storage system comprises a processing circuit configured to switch the energy storage system to the voltage source mode when the energy storage system receives the tripped signal; and
wherein the energy storage system and the switching module are coupled by one or more cables, and the tripped signal is transmitted directly from the switching device to the energy storage system through the one or more cables.
2 . The power grid system of claim 1 , wherein the energy storage system is configured to receive a closed signal from the switching module and configured to switch from the voltage source mode to the current source mode when the energy storage system receives the closed signal.
3 . The power grid system of claim 2 , wherein the closed signal is a feedback signal from the switching device.
4 . The power grid system of claim 2 , wherein the closed signal is transmitted to the energy storage system through the one or more cables.
5 . The power grid system of claim 1 , wherein the bus comprises an AC bus, and the energy storage system comprises a DC/AC converter coupling an energy storage device to the bus; and wherein the energy storage system is configured to receive a reconnection command signal from a control system and configured to synchronize the power grid system with the main grid when the energy storage system receives the reconnection command signal.
6 . The power grid system of claim 1 further comprising a voltage sensing unit configured to measure a voltage of the main grid and provide a voltage signal to the energy storage system.
7 . The power grid system of claim 6 , wherein the energy storage system is configured to determine whether the power grid system is synchronized with the main grid according to the voltage signal.
8 . The power grid system of claim 1 , wherein the energy storage system is configured to send a closing command signal when the energy storage system determines the power grid system is synchronized with the main grid.
9 . The power grid system of claim 1 , wherein the energy storage system is configured to send a closing command signal to the switching module.
10 . The power grid system of claim 9 , wherein the IED is configured to initiate a closing operation of the switching device, and the energy storage system is configured to send the closing command signal to the IED.
11 . The power grid system of claim 1 , wherein the switching device is a high-voltage circuit breaker comprising a contact switch, wherein the switching device is coupled to a first winding of a transformer, the bus is coupled to a second winding of the transformer, and the transformer is configured to step down voltages.
12 . The power grid system of claim 1 further comprising at least one distributed electric generator coupled to the bus.
13 . The power grid system of claim 1 further comprising a transformer, wherein the transformer comprises a first winding coupled to the switching device and a second winding coupled to the bus.
14 . A method for managing a power grid system, the power grid system comprising a switching module and an energy storage system and adapted to supply electric power to at least one load unit through a bus, the switching module comprising a switching device connected between the bus and a main grid and an intelligent electronic device (IED) coupled to the switching device, the energy storage system comprising a plurality of storage cells and configured to supply power electricity to the at least one load unit, the energy storage system coupled to the bus, the energy storage system and the switching module coupled by one or more cables, the method comprising:
monitoring electrical characteristics of power flowing through the switching device to determine a fault is occurring and tripping the switching device in response by the IED;
outputting a tripped signal by the switching device and transmitting the tripped signal directly to the energy storage system through the one or more cables, wherein the tripped signal is a feedback signal indicating a status of the switching device;
receiving the tripped signal from the switching module by the energy storage system through a receiver card of the energy storage system; and
switching an operation mode of the energy storage system from a current source mode to a voltage source mode by a processing circuit of the energy storage system when the energy storage system receives the tripped signal.
15 . The method of claim 14 further comprising:
closing the switching device;
receiving a closed signal from the switching module by the energy storage system; and
switching the operation mode of the energy storage system from the voltage source mode to the current source mode when the energy storage system receives the closed signal.
16 . The method of claim 15 , wherein the closed signal is a feedback signal from the switching device.
17 . The method of claim 15 , wherein the method comprises transmitting the closed signal to the energy storage system through the one or more cables.
18 . The method of claim 15 , wherein closing the switching device comprises sending a closing command signal by the energy storage system to the switching module.
19 . The method of claim 18 comprising sending the closing command signal when the energy storage system determines the power grid system is synchronized with the main grid.
20 . The method of claim 15 , wherein closing the switching device comprises sending a closing command signal by the energy storage system to the IED and initiating a closing operation of the switching device using the IED.
21 . The method of claim 14 further comprising synchronizing the power grid system with the main grid when the energy storage system receives a reconnection command signal from a control system, wherein the bus comprises an AC bus, and the energy storage system comprises a DC/AC converter coupling an energy storage device to the bus.
22 . The method of claim 14 further comprising measuring a voltage of the main grid and providing a voltage signal to the energy storage system using a voltage sensing unit.
23 . The method of claim 22 further comprising determining whether the main grid is restored using the energy storage system according to the voltage signal.
24 . The method of claim 22 further comprising determining whether the power grid system is synchronized with the main grid using the energy storage system according to the voltage signal.
25 . The method of claim 14 , wherein the switching device is a high-voltage circuit breaker coupled to a first winding of a transformer, the bus is coupled to a second winding of the transformer, and the transformer is configured to step down voltages; wherein tripping the switching device comprises opening contacts of the switching device.