MATLAB Simulation of V2G and G2V operation with Three Phase Grid
Introduction
Hello, viewers! Welcome back to LMS Solution. In today's discussion, we'll explore the operation of a vehicle to grid (V2G) system with a three-phase grid. We've developed a simulation model to predict and analyze the behavior of electric vehicles (EVs) during this process.
Simulation Model Overview
The simulation model consists of an EV battery, a direct current (DC) to alternating current (AC) converter, a harmonic filter (LCL filter), a three-phase grid, and a DC-AC inverter. The control mechanism involves a feed-forward decoupling concept, where the grid voltage is used to generate a phase angle (omega t) for further transformations. The grid voltage and inverter current are transformed into the dq0 form for control purposes.
Control Strategy and Reference Power
The system operates based on a feed-forward decoupling control concept, primarily controlling the id (direct axis current) for real power flow between the battery and the grid. A reference current is generated based on the power command, which is converted into id reference using a conversion formula. The id reference is then compared with the actual id, and a proportional-integral (PI) controller processes this error to generate control signals.
Simulation and Analysis
The simulation involves testing the system in both vehicle-to-grid (V2G) and grid-to-vehicle (G2V) modes. The inverter's active and reactive power, the grid's active and reactive power, grid voltage, and inverter current are monitored to analyze the system's behavior.
Vehicle-to-Grid (V2G) Operation
During V2G operation, where the vehicle battery supplies power to the grid, the inverter power, grid power, and battery current are positive. The state of charge (SoC) of the battery decreases as it is in the discharge mode. The phase angle difference between the grid voltage and current is zero, indicating that both are in phase.
Grid-to-Vehicle (G2V) Operation
In G2V operation, where the grid supplies power to the vehicle battery, the inverter power, grid power, and battery current are negative. The SoC of the battery increases as it is in the charging mode. The phase angle difference between the grid voltage and current is 180 degrees, indicating an out-of-phase relationship.
Mode Transition Test
A mode transition test is conducted by changing the reference power command from positive to negative, simulating a shift from V2G to G2V operation. The results show a smooth transition in power, current, and phase angle.
Conclusion
The simulation and analysis of the vehicle-to-grid operation with a three-phase grid demonstrate the effectiveness of the control strategy. The system smoothly transitions between supplying power to the grid and drawing power from the grid, showcasing the versatility of the V2G concept.