Combination of Flywheel Energy Storage System and Boosting Modular Multilevel Cascade Converter

A comprehensive state‐of‐the‐art review of power conditioning systems for energy storage systems: Topology and control applications in power systems

“…Figure 2 presents the configuration of the DC bus PCS for the bidirectional transfer of the electrical energy between the ESS source and DC bus depending on the application requirements. Multiple distributed RES, ESS and DC loads are connected to a 380 V DC bus (e.g., 380 to 800 V DC ) using different PCSs [20–54]. The DC bus PCS should ensure a stable and robust DC bus voltage, especially in the grid‐connected mode, to mitigate the negative influences from the fluctuating RES output, and the voltage level imbalance between the low voltage (LV) level ESS and the high voltage (HV) level bus (DC‐link) [14].…”

“…Next, Figure 2 shows that the AC/DC converter is used to convert the AC voltage and frequency of electric machines (e.g. permanent magnet synchronous machine (PMSM)/induction machine (IM)) connected with the FESS to the DC voltage [49][50][51][52][53][54]. A buck/boost BDDC is connected back to back with the three-phase full-bridge AC/DC converter to increase the DC voltage up to the DC bus level for FESS applications [49].…”

“…The FESS, SC and SMESS have a short‐term energy storage capability (ms to mins), whereas the BESS has a medium‐to‐long‐term energy storage capability (mins to h) [15–17]. This section categorises the popular topologies of the DC/DC, DC/AC and AC/AC converters into DC bus PCS [20–54] and AC bus PCS [55–72] based on the output voltage types at the connected point, as shown in Figure 2. The DC bus PCS ensures the bidirectional transfer of the electrical energy between the ESS source and DC bus.…”

“…With the improvements in the power semi‐conductor switches with a wide band gap (WBG), many topologies of the PCS are now available with reduced total harmonic distortion (THD), smooth output voltage and high efficiency. The configurations of the PCS in ESSs are generally divided into two types based on the output voltage at the connected points: DC bus PCS [20–54] and AC bus PCS [55–72]. First, the former PCS ensures a stable DC bus voltage regulation for the DC‐link or DC grid by charging and discharging the ESS, which uses a DC/DC converter or an AC/DC converter.…”

“…This paper provides critical insights by filling the gap about the advancements of the power converter topologies and their control techniques in the PCS employed for BESS, FESS, SC/UC and SMESS in the power system applications. Generally, the PCS of ESSs consists of a combination of power converters, that is, DC/DC, DC/AC, AC/DC and AC/AC converters [20–72]. With the improvements in the power semi‐conductor switches with a wide band gap (WBG), many topologies of the PCS are now available with reduced total harmonic distortion (THD), smooth output voltage and high efficiency.…”