The Research On Digital Busbar Protection And Anti-TA Saturation Method

With the constant expansion of power system and continuous improvement onvoltage level, the short circuit capacity and time constant of the system is alsoincreasing, which make saturation problem of current transformer (TA) even moreprominent and seriously affect the correct operation of busbar protection. Therefore, thispaper focuses on the issue of how to improve anti-TA saturation capacity of busbarprotection.Firstly, this paper introduces the existing anti-TA saturation method of busbarprotection home and abroad, and makes clear the major work by understanding theresearch status of anti-TA saturation on busbar protection. Then the author conductstheoretical and simulation analysis to TA saturation, and obtain some valuable TAsaturation characteristics, which can be used to improve or overcome the impact of TAsaturation on the busbar protection. Finally, focus on theoretical analysis and simulationon bus protection method based on transient traveling wave, a large number ofsimulation graphics and numerical analysis results are given, which verify thecorrectness and effectiveness of this kind of protection method. Furthermore, the authoralso conducts analysis and simulation on key techniques that can be used for busbarprotection based on transient traveling wave.On the basis of studies above, this paper proposes a new busbar protection methodbased on measured surge impedance. This protection method identifies fault location bycomparing magnitude and polarity of measured surge impedance of each line on busbar,which is free from the influence of various fault types, distance of fault external, faulttransition resistance and the initial angle, and have a high sensitivity in all case. Thetheoretical analysis and simulation data show that the new busbar protection based onmearsured surge impedance is accurate, reliable, rapid response and sensitive. Inaddition, morphological filter is also applied in transient busbar protection, in order tosolve the problem that transient protection is vulnerable to be affected by pulse andnoise singles. In order to overcome the shortcoming that single modulus of traditionalphase-mode transformation matrix can not reflect all fault types, a phase-modetransformation theory is applied to the transient busbar protection. As a result, thecomputation of busbar protection is reduced.