Synthetic Discrete Inertia

TL;DR

This work tackles frequency stability in grids with high penetration of inverter-based resources by enabling synthetic inertia through a large population of discrete devices (DDs). It introduces a virtual swing control framework realized by DDs modeled as a hybrid automaton and validates it via two large-scale case studies (WSCC 9-bus and the all-island Irish transmission system). The results show that, with high device granularity and asynchronous operation, DDs can sustain power balance and improve dynamic performance, though cycling risks must be mitigated through careful sizing and coordination; CDD deployment can further enhance performance when combined with conventional grid-forming resources, and SVC can reduce voltage oscillations. The findings indicate that discrete-inertia strategies are scalable and practically applicable to future grids.

Abstract

This letter demonstrates how synthetic inertia can be obtained with the control of flexible discrete devices to keep the power balance of power systems, even if the system does not include any synchronous generator or conventional grid-forming converter. The letter also discusses solutions to cycling issues, which can arise due to the interaction of uncoordinated discrete inertia controllers. The effectiveness, dynamic performance, and challenges of the proposed approach are validated through simulations using modified versions of the WSCC 9-bus test system and of the all-island Irish transmission system.

Figures (7)

• Figure 1: Power balance at buses 1, 2, 5 and 7 -- 9-bus WSCC System.
• Figure 2: Active Power injection from groups of DDs and accumulated contribution of all DDs -- 9-bus WSCC System.
• Figure 3: Power injection at bus 3 for different DDs' size combination -- 9-bus WSCC System.
• Figure 4: Voltages on the busses -- 9-bus WSCC System.
• Figure 5: Frequency support from DDs -- Irish System.