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This paper defines underlying performance quality measures for designing, optimizing, setting and evaluating the protective relaying algorithms and equipment. The paper starts with evaluation of digital measuring algorithms, and gradually introduces the performance indices for the operating principles, relays and protection systems. Multi-objective formal ranking methods based on fuzzy set theory are used to combine diverse measures into composite performance indices enabling evaluating and optimizing various functions of protective equipment. Index Terms--Fuzzy sets and logic, multi-objective evaluation, protective relaying, testing.

This paper presents a new method for accurate linking of diverse simulation techniques. The method employs a Functional Modeling (FM) approach and facilitates linking of different simulation techniques as well as combining separate simulation engines. In addition, the presented method enables system decomposition with freely selected cuts as well as natural and efficient parallel computations. Discussion of advantages and various applications is also included. Index Terms--Decomposition, digital simulation, functional modeling, numerical methods.

This paper reviews a number of mathematical models used to represent the nonlinear behavior of the magnetic core of instrument transformers. Models of instrument transformers using these core representations are presented. The transient response of the instrument transformer is compared to actual test results recorded in the laboratory. The paper provides practical guidelines as to which of the physical elements of instrument transformers are important to model during transient studies and which elements could be ignored without sacrificing the accuracy of the simulation results. The electromagnetic transients program (EMTP) data files used to generate the models are also provided in the appendix to help new EMTP users model instrument transformers for evaluation of high-speed protective relaying systems. Index Terms--Coupling capacitor voltage transformers, current transformers, EMTP modeling, simulation, voltage transformers.

The modeling of power transformer faults and its application to performance evaluation of a commercial digital power transformer relay are the objective of this study. A new method to build an EMTP/ATP power transformer model is proposed in this paper. Detailed modeling of the transformer relay is also discussed. The transient waveforms generated by ATP under different operating conditions are utilized to evaluate the performance of the transformer relay. The computer simulation results presented in this paper are consistent with the laboratory test result obtained using an analog power system model. Index Terms--Analog power system model, digital relay modeling, electromagnetic transients program, power transformer modeling.