State-of-the-Art Grid Stability Improvement Techniques for Electric Vehicle Fast-Charging Stations for Future Outlooks

Abstract

The growing trend for electric vehicles (EVs) and fast-charging stations (FCSs) will cause the overloading of grids due to the high current injection from FCSs’ converters. The insensitive nature of the state of charge (SOC) of EV batteries during FCS operation often results in grid instability problems, such as voltage and frequency deviation at the point of common coupling (PCC). Therefore, many researchers have focused on two-stage converter control (TSCC) and single-stage converter (SSC) control for FCS stability enhancement, and suggested that SSC architectures are superior in performance, unlike the TSCC methods. However, only a few research works have focused on SSC techniques, despite the techniques’ ability to provide inertia and damping support through the virtual synchronous machine (VSM) strategy due to power decoupling and dynamic response problems. TSCC methods deploy current or voltage control for controlling EVs’ SOC battery charging through proportional-integral (PI), proportional-resonant (PR), deadbeat or proportional-integral-derivative (PID) controllers, but these are relegated by high current harmonics, frequency fluctuation and switching losses due to transient switching. This paper reviewed the linkage between the latest research contributions, issues associated with TSCC and SSC techniques, and the performance evaluation of the techniques, and subsequently identified the research gaps and proposed SSC control with SOC consideration for further research studies.

Development and Implementation of a Smart Charging System for Electric Vehicles based on the ISO 15118 Standard

“…When charging starts (representation B), the charging screen makes available the remaining information, which is the remaining time to full charge (5) presented in hour-minute format (hh:mm), the EV target current (7), the EV target voltage (8), EVSE identifier (9) and the communication session identifier (10). While charging, the vehicle user can yet request the charge to stop through this interface, using the stop button (6).…”

“…At a global level, taking into account the average carbon emissions used for electricity generation (518 grams of carbon dioxide equivalent per kilowatt-hour [518 g CO2-eq / kWh]) [2], an EV emits a smaller amount of greenhouse gases than the average internal combustion vehicles. In 2022 the global market share of EVs reached 14% (more than 26 million EVs around the globe) [3], however, the uncontrolled charging requirements of this growing fleet represent a major challenge for the electrical grid, especially if the charging demand from EVs coincides with the peak consumption periods already existing in the grid, which can lead to its overload [4] [6].…”

“…The two main solutions to this challenge could be, on the one hand, to introduce Renewable Energy Sources (RES), and particularly those that are generated at the distribution level, reducing the need for conventional energy sources, and, on the other hand, the introduction of demand response mechanisms, that allow adjusting the charging power of EVs according with the power output from 2 these RES. Through this mechanism, known as Smart Charing, EVs can minimise the requirements they place to electrical grids, by shaping their demand pattern, by varying the intensity and charging periods [4] [6]. At this level, EVs can be thought as an additional storage unit, either for the sole purpose of mobility, but also to support vehicle-to-grid (V2G) energy transfers [2].…”

“…Mostly used in the Alternating Current (AC) power transfer mode, the signalling carried out through these pins only indicates when the EV is connected to the EVSE and what is the available electrical current that the supply equipment can supply to the vehicle. That reduced set of control options limits the implementation of smart charging solutions [1, 5,6].…”

Development and Implementation of a Smart Charging System for Electric Vehicles Based on the ISO 15118 Standard

“…At a global level, taking into account the average carbon emissions used for electricity generation (518 g of carbon dioxide equivalent per kilowatt-hour [518 g CO 2 -eq/kWh]) [2], an EV emits a smaller amount of greenhouse gases when compared with the average internal combustion vehicles. In 2023, the total number of EVs on the roads reached 40 million globally [3]; however, the uncontrolled charging requirements of this growing fleet represent a major challenge for the electrical grid, especially if the charging demand from EVs coincides with the peak consumption periods already existing in the grid, which can lead to its overload [4][5][6].…”