Fundamentals of short-circuit protection for transformer

This thesis presents the design and implementation of computer components and hardware test systems (TSs) for assessing the operability of digital current protection in electric installations, along with their modeling in the MATLAB-Simulink dynamic simulation environment. The mathematical model for any component of the electric power system, viewed as a generalized electric power facility, is grounded in both rigid and flexible models. Rigid models, based on the mathematical descriptions of the electrical and magnetic circuits of power system elements, serve as benchmarks for comparing the results of simulating similar facilities. In contrast, flexible models of a generalized electric power facility are designed for integration into the MATLAB-Simulink dynamic simulation system's library, which includes the Sim-Power-Systems extension package. These models focus on the simulation of electrical devices. The thesis delves into the detailed calculation of parameters for the main library blocks of Sim-Power-Systems, which form the basis of the power system model. It also introduces models for a three-phase group of current transformers, featuring a secondary winding and load connection based on the "star with a neutral wire" (Y-connection) scheme, and a model of digital current protection—both crafted using standard Simulink blocks and not part of the core library. Furthermore, the thesis explores the use of differential protection relay and fuzzy logic for power transformers, demonstrating their effectiveness in defending against internal and external faults, and in distinguishing between fault and non-fault conditions. Utilizing the MATLAB/SIMULINK platform, this research offers valuable insights into the performance and capabilities of the differential protection relay system.