Four-Quadrant Operations of Bidirectional Chargers for Electric Vehicles in Smart Car Parks: G2V, V2G, and V4G

Abstract

This paper presents the four-quadrant operation modes of bidirectional chargers for electric vehicles (EVs) framed in smart car parks. A cascaded model predictive control (MPC) scheme for the bidirectional two-stage off-board chargers is proposed. The controller is constructed in two stages. The model predictive direct power control for the grid side is applied to track the active/reactive power references. The model predictive direct current control is proposed to achieve constant current charging/discharging for the EV load side. With this MPC strategy, EV chargers are able to transmit the active and reactive powers between the EV batteries and the power grid. Apart from exchanging the active power, the vehicle-for-grid (V4G) mode is proposed, where the chargers are used to deliver the reactive power to support the grid, simultaneously combined with grid-to-vehicle or vehicle-to-grid operation modes. In the V4G mode, the EV battery functions as the static var compensator. According to the simulation results, the system can operate effectively in the full control regions of the active and reactive power (PQ) plane under the aforementioned operation modes. Fast dynamic response and great steady-state system performances can be verified through various simulation and experimental results.

Active and Reactive Power Collaborative Optimization for Active Distribution Networks Considering Bi-Directional V2G Behavior

“…The reactive power operation of the EV is based on the smart charging pile, which has gradually become the focus of attention because of its capability for four-quadrant operation [20]. The representative topology is shown in Figure 2.…”

A comprehensive review on electric vehicles smart charging: Solutions, strategies, technologies, and challenges

“…Different ancillary services such as power quality services, grid loss reduction, voltage (or reactive power) support, frequency response services, constraint management, etc., may be provided by EVSC [21]. For proving ancillary services by EVs (through EVSC), both vehicle-to-grid (V2G) and grid-to-vehicle (G2V) strategies are needed to enable bidirectional power exchanges [22]. In the V2G mode, EVs charge to improve the grid characteristics in peak load hours, whereas in the G2V mode, EVs are charged to meet the batteries' energy needs [23].…”

Review on Control Techniques for EV Bidirectional Wireless Chargers

“…In Quadrant III and IV, the charger delivers reactive power so that it is working as a capacitive load. Some researchers referred to the control of P and Q as the Vehicle-for-Grid (V4G) operations [7]. Advanced algorithms will work in the quadrant areas for different values of P and Q.…”

“…However, initial approaches that do not consider the adjustment of a reactive power to a reference power different from null just move on the axes of Figure 1. Thus, there are eight operation modes as identified by [7]:…”