Simulation And Analysis System For Power Transformer Relay Protection

Power transformer is one of the most important main equipment in the power system, andit plays an important role of transforming voltage and exchanging power in the power system.Its operating conditions affect the safety and stability of power system directly. But in recentyears, the correct operation ratio of transformer protection is far lower than the line protection,so the simulation study of power transformer fault has very important theoretical significanceand practical value. This paper mainly does the following work aiming at some questions oftransformer protection.This paper chooses the common three-phase transformer in the power system as theresearch object, introduces the fundamental principle of main protection and back-up protectionof transformer, and mainly analyses the differential protection theory, the mechanism of themagnetizing surge current and blocking criterion, the unbalance current in the differentialcircuit and the method of reducing the current.This paper sets up the outside fault model and the internal fault model of transformerbased on the SPS module in the Matlab/Simulink according to the fundamental principle, thelogical components, the protection algorithm and the implementation processe of thetransformer microcomputer relay protection. This model simulates each function module of thetransformer relay protection, simulates the actions of the transformer relay protection device.The model simulates and studies the transformer in all kinds of type of faults, the simulationresults are in accord with the theoretic analysis, proving the correctness and validity of thesimulation model.This paper deeply understands and studies domestic and foreign digital simulation methodsof relay protection, and designs the simulation and analysis system of power transformer relayprotection based on Matlab with the use of the relay protection digital simulation technique.Based on the Simulink simulation model and GUI interface design, the system combines the twoeffectively through the programming of M file. The system provides the simulation model ofdifferential protection, overcurrent protection, ground protection and over-excitation protection,the user can set the main equipment parameters, the setting value of protection and the type offaults, furthermore, the simulation results under all kinds of type of faults can show the failurecurrent, the voltage, operation signals and so on in the form of graphics. The system has afriendly interface of man-machine, and it is easy to operate, its simulation results can be showedin graphics, which can meet the needs of knowing the protection principle well and making fault analysis for relay protection workers. It also has practical value in the relay protection trainingand teaching.