Power Transformer Protection Devices Research And Anti-interference Design

Microcomputer-basedrelay protection is a reliable guarantee for the stableoperation of the power system. In recent years, increasing the capacity of thepower system, the system structure increasingly complex so that the computerprotection device is particularly important, especially for the protection ofhubpower transformers requirements are particularly demanding. Powertransformer microcomputer protection device since it was widely used,thereare still a variety of issues. In this paper, analysis and study of powertransformers for several common issues of computer protection and propose animproved method.This paper describes the types of power transformer differentialprotection and as well longitudinal differential protection principle、composition, analysis of the phase compensation principles of transformerlongitudinal differential protection and their differences with the linedifferential protection, on this basis, presents advantages in terms of reliabilityand sensitivity of two new differential protection principle, that the currentdifferential protection phase correlation and difference method based ondifferential protection. Through theoretical derivation of the new principledifferential protection, verify its feasibility and advantages, and discussed indetail of these two new differential protection principle and characteristics.Then, principle and characteristics of the protective CT(currenttransformer) made a systematic exposition, CT saturation model built byMATLAB simulation, the secondary current waveform captured and record theproportion of each harmonic component of CT saturation, to providetheoretical basis for the anti-jamming measures. After analyzing the traditionalprevention measures of CT saturation, on this basis, proposed that CTsaturation from the root of the problem to solve can be non-core Rogowski coilreplacement of traditional CT. In order to improve the level ofanti-electromagnetic interference of power transformer microcomputer protection, respectively start from several key modules of protection which isoften interfere with computer intrusion, such as power modules、communication modules、 data acquisition modules and micro control unitmodule, detailed study ofeach moduleindividuallyinterferenceprincipleandimprovement program.Finally, a detaileddescriptionof thetransformer differentialprotectiondebuggingmethods, with ZhuHai Ole power distribution automation limitedcompany hardware, using dynamic simulation conducted differential protection,the second harmonic ratio brake differential protection, differential protectionbased on time difference method of trial, verify that the new principle ofdifferential protection in terms of reliability, sensitivity than conventionaldifferential protection advantages.