ANALYSIS OF OVERCURRENT RELAY CHARACTERISTICS USING IDMT MODEL

Abstract

The issue in the context of power system protection, leads to a critical void in design and implementation of mechanisms for protection from overcurrent under IDMT (Inverse Definite Minimum Time) settings. The above identified problem reveals a crucial gap in designs for tools overseeing the IDMT overcurrent protection of power systems. Lack of systematic prescription of design steps and procedural development in numerical IDMT overcurrent relay characteristics leads to the faults to persist in the network, despite the research and education activities conducted pertaining to power system protection. Absence of standardized methodologies and tools incurs challenge toward the reliability and the effectiveness of protection schemes. This research tends to fill this gap with the design and validation of the IDMT overcurrent relay characteristics based on IEC 60255 standards. The process that are followed are a systematic methodology development, MATLAB/Simulink simulation of the designed characteristic, its implementation and performance with respect to selectivity, speed, and reliability. This chapter details the software implementation to a great extent by taking an example of a Simulink model of an electrical system with an IDMT protection scheme. The most important highlight of this research is the scope for a proper methodology, which would function as a tool for understanding efforts to get the maximum benefits from IDMT overcurrent protection in electric power systems.