In‐depth study of the application of solid‐state transformer in design of high‐power electric vehicle charging stations

Abstract

Solid-state transformers (SST) will play an important role in future electric power distribution. The SST usually used for traction and transportation systems. However, it can be employed for other applications. For example, electric vehicles (EVs) are confronting the increased demand now, and the service provider must expand the infrastructures such as the high-power EV charging stations in urban areas. One solution for designing a high-power charging station is the SST-based charging stations, which can be connected to the distribution network. This study proposes an SST-based EV charging station, which is connected to the 20 kV catenary without any low-frequency transformer and provides the necessary power for connected EVs without affecting the grid power quality. The proposed EV charging station has high flexibility such that it can be integrated with distributed generation. It also provides vehicle-to-grid, grid-to-vehicle and sun-to-vehicle features. Besides, it can inject reactive power to the grid based on its free capacity. This study also proposes an advance virtual flux predictive power controller to improve the immunity of this structure against voltage harmonics. Exact simulations have been done for a three-phase 20 kV/ 600 V/360 kVA station with different scenarios. Results verify the performance of this infrastructure.

Hybrid Modular Multilevel Converters for High-AC/Low-DC Medium-Voltage Applications

“…There is hence a strong impetus to reduce SM capacitor size, making the converter more power-dense. Assuming the SM capacitor reference voltage is VSM, the capacitor ripple coefficient, δ is defined as (14). (14) Here ∆VSM is the peak-to-peak voltage ripple at SM capacitor voltage.…”

“…Assuming the SM capacitor reference voltage is VSM, the capacitor ripple coefficient, δ is defined as (14). (14) Here ∆VSM is the peak-to-peak voltage ripple at SM capacitor voltage. Assuming that the ripple is the same across all SMs in the same arm, the required chain link capacitor energy storage, ECL is related to maximum energy deviation, ∆E, δ and number of SM, NSM for total power, S, in per unit value as [40]: (15) Here arm energy can be derived as a function of arm voltage and current in (16).…”

“…Solid state transformers (SSTs) have also been explored for application within EV charging stations, as shown in Fig. 1(b) [13], [14]. SST is used for direct MV-AC to LV-DC conversion, followed by LV DC-DC converter [15] - [17].…”

Modeling and Control of a Hybrid Modular Multilevel Converter for High-AC/Low-DC Medium-Voltage Applications

“…Solid state transformers (SSTs) have also been explored for application within EV charging stations, as shown in Fig. 1(b) [13], [14]. SST is used for direct MV-AC to LV-DC conversion, followed by LV DC-DC converter [15], [16], [17].…”

Mitigation of Voltage Sag, Swell, PF correction and THD reduction using SST & DC breaker implementation in SST based charging station for EV: Chaotic GWO technique

“…4 The developed countries transport sector is investing in EVs. 6 Figure 2 shows types of SST.When non-linear loads and power electronics equipment are used excessively at the (PCC), harmonic currents are generated, which reduce the quality of the electrical power. 7 The DC-link capacitor, located on the front of the VSI, is used to manage reactive power for the grid.…”