Abstract: In this study, we present a method for the state evaluation of the zero sequence parameters. This method consists on connecting between each phase to earth one variable impedance reactor, which permit us reducing the fault current value in the ground fault point as well as making possible the voltage imbalance compensation. This can be accomplished by setting to optimum value the phase to earth reactance of inductive character to be in tune with the network phase to earth capacitance of the corresponding phase, in order to get a parallel resonance regime. The inductive phase to earth reactance is connected across the network phase and the ground potential. In contrast to the previously used method of inductance connection between the system neutral point and the ground potential, this solution provides apart from maximum total capacitive current compensation capability even an equalization of phase voltages under failure free condition within networks with substantial phase capacitance imbalance. By goal-directed variation of the phase earth reactance in the earth fault point during the ground fault, the watt fault current component can be efficiently eliminated, which is the main advantage of this method, since the control of the zero sequence parameters (at 50 Hz frequency) can be done safety.
Messaoud Boukhenaf , Ali Haddouche and Noureddine Guersi , 2007. Three Phases to Earth Reactors for the State Evaluation of Zero-Sequence Systems. Asian Journal of Information Technology, 6: 200-206.