Research On The Detection Of Faulty Line In Non-Direct Grounded Neutral System

Non-direct grounded neutral system has been widely used in low and medium voltage distribution system in some countries and the single phrase to ground fault is the main one of this kind of system. Since the compensation of extinction-coil, when the single phrase to ground fault occurred, there is almost no difference between the current of normal lines and faulty lines. Plus the same line voltage at load sides after the failure, the power system can keep operation for a while with the fault. Therefore, this kind of system brings strong power supply reliability. However this system also has a huge disadvantage that is it is hard to determine faulty lines and the prolonged operation with fault will cause damage on power system equipments. Because currently methods are always not consummate and errors often occur, cutting outgoing lines one by one for faulty line detections are frequently adopted in practical operations. This is an unacceptable way of reducing the power supply reliability. So it is necessary to find some new ways for the faulty line detection.Synergic theory is a burgeoning science. The major objective of this theory is to find universal laws among different things. Synergic theory described the system's behaviors when the system was near the critical point and presented adiabatic approximation theory and order parameter theory. It considered that the system's evolution was controlled by order parameters. The final structure and orderly degree of the system's evolution were depended on order parameters.Under the exact analysis of the single phrase to ground fault in Non-direct grounded neutral system, this paper presented a new way for faulty line detection built upon the synergic theory. This method firstly adopted the adiabatic approximation of synergic theory to divide variables of equations, which described the faulty system, into fast transition parameters and slow transition parameters and eliminated the first group to simplify the equations. As a result, the original complex equations had been mapped into order parameter equations which were mare simple. Then this method considered the procedure faulty lines detection as the operation in a kinetic system of order parameters and studies the development of samples in this system to determine their structure and final state for choosing the faulty line. This method picks up the whole characteristic of patterns. It can avoid difficulty of deciding distinctiveness as well. Experiments proved that this method worked well and it comported a strong noiseproof feature.