UPGRADATION OF PROTECTION OF POWER SYSTEM FROMFREQUENCY VARIATION USING MICROCONTROLLER BASED NUMERIC RELAY. International Journal of Advance Engineering and Research Development (IJAERD), [S. l.], v. 1, n. 7, p. 138–145, 2014. Disponível em: https://ijaerd.org/index.php/IJAERD/article/view/5493. Acesso em: 8 sep. 2025.