This paper presents a comprehensive framework, which includes a quantification procedure for various Frequency Response Residual-Sources (FRR-Ss), including System Inertia, $M_{sys}$ ( = 2H), System Self-regulation ($D_{self}$), Governor Response ($FR_{Gov.}$), and Effective Governor-Droop ($R_{eff.droop}$) performance. This framework leverages Phasor Measurement Unit (PMU) data, capturing sequence-of-events frequency dynamics from a critical location following a cascaded tripping event. Within this framework, a time duration of 20 sec, starting from the onset of the disturbance, employs suitable approaches to analyze measured frequency in two network cases: ‘Case-I’ real-time simulation in IEEE-24 bus system (RSCAD/RTDS) and ‘Case-II’ real-frequency event measurements from the Indian power system for the aforementioned FRR-Ss quantification. The quantified results for ‘Case-I’ are as follows: $M_{sys}$ = 20.9855 sec, $D_{self}$ = 2.477 p.u, $FR_{Gov.}$ = 10.680 p.u, and $R_{eff.droop}$ = 9.363\%, and results for ‘Case-II’ are 5.0289 sec, 1.2116 p.u, 1.094 p.u, and 91.4076\% respectively. This effort enhances an improved understanding of system frequency dynamics and estimating the frequency response requirements during cascaded tripping events of low-inertia power systems. Finally, the paper provides insights into operational measures and highlights various challenges faced.

Low-inertia power systems, including frequently incorporating inverter-based smart appliances (IbSA), introduce challenges concerning voltage and frequency responses, resulting in increased localized frequency deviations and wide-area frequency fluctuations (WA-FF). These disturbances can trigger cascading effects, potentially leading to ‘blackouts’ if not promptly managed. Within IbSA, certain critical load categories can promptly control voltage and frequency signals from external measurements, enabling them to adapt to variations in active power around nominal ratings. In this study, these loads are referred to as ‘smart exponential dynamic loads’ (SDLExpo). The power reserves of SDLExpo are quantified and aggregated at power stations operating at the 400/230/138kV transmission level, collectively forming a wide-area active power reserve (WA-APR). SDLExpo integrates with the demand response-aggregated frequency service provider (DR-AFSP) regulation market concept, leveraging cost-effective communication and measurement signals. Finally, a distributed control frequency signal-based dynamic load (DCFSbDL) technique is proposed for real-time regulation of WA-APR in a coordinated manner following WA-FF events. The sensitivity analysis followed by case studies conducted on IEEE-39 and IEEE-24 bus networks assesses responses to infeed loss, load rejection, cascaded tripping, and renewable energy integration, demonstrating its effectiveness. The study shows that SDLExpo collectively provides active power reserves which reduce frequency deviations, and expand the upper frequency margin to safely accommodate renewables, thereby enhancing system stability.