“UPGRADATION OF PROTECTION OF POWER SYSTEM FROMFREQUENCY VARIATION USING MICROCONTROLLER BASED NUMERIC RELAY” (2014) International Journal of Advance Engineering and Research Development (IJAERD), 1(7), pp. 138–145. Available at: https://ijaerd.org/index.php/IJAERD/article/view/5493 (Accessed: 8 September 2025).