Study On Single Phase Ground Fault Detection In Neutral Resonant Grounded Distribution Networks

Neutral ineffectively grounded modes are widely employed in medium and low voltage distribution networks of China. They can contribute to the reliability of power supply, on the other hand the weak currents caused by them make it hard to ground fault detection. It is an important research subject in neutral ineffectively grounded systems that detecting the ground fault accurately. The situation that the neutral resonant grounded systems (NES) were mostly employed requires the thoroughly study on the ground fault detection in this mode.The paper makes a deep analysis on this issue, aiming to explore more efficiency criteria, which can coordinate with magnetic flux controllable arc suppression coil (MFC-ASC) appropriately. The voltage and current characteristics in NES when single phase ground fault occurred were first found. Based on the characteristics found, advantages and disadvantages of various methods were detailed discussed. And with the aid of theoretical analysis, on the basis of the operational features of MFC-ASC, three criteria with complementarily features were presented. They rely on changing the measure of dissonance of the system and injecting the resonant current.Considering that the installations do not work in real time, the former three criteria were engaged to form the auto-adaptive program for fault detection by setting their credibility and the maximum detectable resistance. This program will automatically work according to the features of the system and the fault types. The conclusion is reached by synthetic decision.The MATLAB simulation model was created to make a certification to the result of theoretical analysis, and each criterion's valid area was determined. It is proved by the simulation results that the program can enhance the accuracy of fault detection and can detect rapidly. At the same time it can work during the arc suppression coil working. The integration device can not only take the advantages of MFC-ASC but also reduce the additional investment.