The energy storage systems (ESS) are crucial components in electric power and electrified transportation systems due to the strict requirement on power balance between generation and load demand. The ESS adds valuable flexibility to the power grid and transportation by mitigating the mismatch of generation and load demand. Specially, with recent trends on renewable distributed generation sources (DGS) and electric vehicles (EVs), distributed ESS are becoming more popular in several applications such as DGS based microgrids and EVs. However, several ESS technologies differ in their nominal capacities, discharge/response time, lifetime, and participation scales in ancillary services. Therefore, the proper coordination and aggregation between various technologies/facilities of ESS are required to ensure efficient ancillary services and cost-effective investments
Fig. 1: Storage utilization and integration.
1. Energy Storage Systems for Electrical Power Applications
ESSs can be utilized for several applications such as smoothing RES power generation, load shifting, energy arbitrage, scheduled power generation of hybrid renewable power plant (HRPP), blackout restoration, and efficient ancillary services. Therefore, APEC research team proposed different strategies on sharing, hybridizing, coordinating, and aggregating among different ESS facilities and technologies for multitasking multi-scale applications in the context of deregulated distributed power energy and electrified transportation systems. APEC team aim to investigate the proposed strategies on different types and scales of ESS considering its functionalities on distribution and transmission level of power systems, especially the interlinks between electric power and electrified transportation systems as shown in Fig.2.
Fig. 2: Matching of ESS technologies and Applications.
APEC team investigated several applications of different types of ESS considering its adequacy for islanded and grid-connected operations, grid interface schemes, control strategies, ESSs coordination, performance degradation, and economical installation for efficient operation of smart grid. In addition, ESSs can improve the power quality and the stability of power grid with high penetration of renewable power generation resulting in reducing CO2 emission by decreasing fossil fuel consumption.
2. Coordination of Smart Energy Storage Systems
Hybrid ESS and smart ESS systems represent two likely directions, one to obtain a high-power capacity and a fast action time and the other to facilitate the convenience of ESS. Aggregating strategy is also essential for an efficient utilization of shared mobile ESS in the context of electric vehicles and electrified transportation. The methodology for coordinating and aggregating is based on dynamic responses of ESSs as actuators of the overall control system consisting of cascaded loops following the IEC/ISA62264 standard as shown in Fig.
3. By the mentioned strategies, the ESS can be combined at different levels from generation, transmission, distribution, and customer scale.
Fig. 3: Methodology for coordinating and aggregating ESS by matching functionalities and characteristic of ESS to the hierarchical control structure in power grid based on IEC/ISA 62264.