Relay Protection Simulation Experiment Platform Based On Signal Adaptive THD Reconstruction

Power system relay protection is an important guarantee for the normal operation of power system.At the same time,power system relay protection is also an important professional course for electrical engineering with its strong practicality,application and comprehensiveness.In the course of research and teaching,it is necessary to combine experiments in order to analyze various protections under the operation state of complex power system.Therefore,designing an economical,practical,accurate and efficient relay protection simulation experiment device is of great significance to relay protection research and teaching.This paper first analyzes the advantages and disadvantages of traditional relay protection experimental equipment.For the common problems of experimental equipment,such as single function,expensive cost,and neglect of solver error,a relay protection simulation experiment platform based on MATLAB software and digital-to-analog conversion hardware system is designed.The platform relies on MATLAB’s powerful simulation operations and program processing functions.Through the high performance DA conversion module and the power amplifier circuit,the analog quantity obtained from the simulation is transmitted to the relay protection equipment,and the real-time acquisition of the motion signal is made.Then analysis the numerical error introduced by the numerical algorithm in the simulation process,and combined with the power system simulation model for analysis.In order to solve the error introduced by the kind of simulation algorithm and make the signal transform and output stably,a signal reconstruction method based on the wavelet theory and the harmonic distortion rate of voltage and current is proposed.The principle of the reconstruction method and the derivation process of the practical formula are introduced in detail,and the complete adaptive reconstruction process is given in combination with the experimental process of the experimental platform.With the comparison of simulation data,when eliminating the error introduced by the solver,the proposed method is obviously superior to the commonly used filtering methods.On this basis,in order to make the experiment system has a good economy and to the applicability of different frequency signals,the voltage and current power amplifier circuit was designed by discrete component.The design is a combination of high voltage,high current power amplifier system and the characteristic of the modern OCL precision audio power amplifier.The structure of the emitter buffer driver stage and the vibration dissipation capacitance is introduced into the high voltage power amplifier system,and the power amplifier module is simulated and tested by software.Finally,the feasibility of the platform is verified by the practical microcomputer protection test.