Brief About the Testbed:
A 50 kW microgrid testbed, as shown below, is being set up at our laboratory. The DC side energy sources consist of a 10 kW Solar emulator, a 5 kW Fuel cell emulator, and a 55 kWh Li-ion battery bank. All these DC sources are connected to a DC distribution panel at 380 V. The AC side energy sources consist of a 10 kW synchronous generator, a 10 kW Doubly-fed induction generator-based wind farm, and a 5 kW Permanent magnet synchronous generator-based wind farm. All these sources are connected to an AC distribution panel operating at 3-phase, 415 V, and 50 Hz frequency ratings. This AC bus is connected to the utility grid through a synchronization panel. The bidirectional flow of energy can be carried out by a Bidirectional AC/DC converter of 25 KVA, which is connected between the AC and DC bus. All the energy sources except the synchronous generator are having their corresponding power electronics converters configured with FPGA boards to control their outputs. A central monitoring and control system is proposed, which will be able to study the current status of the system, visualize inputs from all the converters as well as send control signals back to the converters to change their outputs accordingly. The function of the Battery management system and the bidirectional DC/DC converter is to charge the battery under normal operation as well as discharge and supply to load in case of any contingency. In addition, an Intelligent Transfer switch is proposed, which will also be connected between the AC bus and the utility grid. The function of the switch is to disconnect the microgrid from the grid in case of any contingency (e.g. fault) within the microgrid or outside. At that time, the microgrid will work in islanded mode. Also, when the fault is cleared, the switch will reconnect the microgrid with the utility grid, and that is called as grid-connected mode. The control signal for the switch will also be sent from the central controller. PHIL setup having 7.5kVA linear four-quadrant power amplifier is in process for testing and validation of the microgrid testbed. Its Implementation and HIL testing of control schemes for energy management within hybrid AC/DC microgrid will be done.
Architecture of the Testbed:
Key research works were executed with this testbed:
- PV load with a battery storage system for voltage regulation and energy management has been performed by using the test-bed.
- Fuel cell with load and battery charging and discharging has been performed.
- All the modules were tested individually in stand-alone mode.