Study For Novel Algorithm Of Power Transformer Protection

Second-harmonic restraining technique and gap-detecting technique are widely used to distinguish magnetizing inrush current and internal fault current. However, there are so much influence factor of electric current waveform of transformer, furthermore, some influence factor are random, therefore to adjust the operation value is very difficult in the principle based on the characteristic of electric current, so the operation of protection can not be correct absolutely, so relay based on the characteristic of electric current may maloperate and delay the operate time. Therefore, the study for new transformer protection projects are challenge for us. Due to the nolinear of transformer, it is more reasonable to characterize the operation feature of transformer in different operation state with voltage and current signal. Therefore, the paper studies and proposes an new transformer protection algorithm based on power.This paper presents a new approach of transformer protection based on the theory of instantaneous reactive power. Firstly, system model is constructed by RTDS(Real—Time Digital Simulator). RTDS is used to simulate kinds of magnetizing inrush current at different switched moment when energized transformer without loads and kinds style of fault.Then, the average active power and average reactive power for one power period of transformer in different operation state can be calculated, and to get the new algorithm based on the different relation of them in the different state.Finally, the algorithm is tested by RTDS . The algorithm is proved to be fast, reliable, accurate and simple, what's more, it does not ask or too high sampling frequency.