Analysis of the Impact of Distributed Generation on the Frequency Stability and Rotational Inertia of the Electric System

This study evaluates the impact of the integration of non-synchronous distributed generation on the frequency stability, rotor-angle response and dynamic performance of the electrical system associated with Substation 50 La Troncal (Ecuador). The network was modeled in DIgSILENT PowerFactory 2024 with six busbars, and eight renewable-penetration scenarios (15–50% of the 32.8 MW demand) were assessed under N-1 (loss of the COAZUCAR TG3 generator) and N-2 (TG3 plus the Ocaña 2 line) contingencies applied at t = 1 s over a 20 s horizon. Steady-state results showed voltage profiles within acceptable ranges and no overloads, whereas the dynamic analysis revealed non-compliances, with average ROCOF of 0.772 Hz/s, frequency nadir of 59.192 Hz and angular deviation of 8.75°. A battery energy storage system (BESS) with virtual inertia was then implemented, improving the nadir to 59.672 Hz, the ROCOF to 0.220 Hz/s and the angular deviation to 6.10°. An ANSI 51 overcurrent scheme (Siemens SIPROTEC 7SJ6001) installed on the 69 kV line at B3 was verified with operating times compatible with the protection requirements. The combination of energy storage, virtual inertia and conventional protection constitutes a technically viable alternative to increase non-synchronous distributed generation while preserving stability and operational security.