Automatic tuning of arc-extinguishing reactors for a medium-voltage power system 6-35 kV applying the method of two frequencies auxiliary currents overlap

Abstract

The urgency of the discussed issue is caused by the need to control automatic tuning of the arc-extinguishing reactor in a medium-voltage power system. Full effect of the application of such reactors takes place in the case if ARC-extinguishing reactor is automatically adjusted coils in resonance with the network total capacity. To realize automatic adjustment it is necessary to obtain continuously the information on deviation from resonance in the form of electrical signal. The main aim of the research is to design the method for controlling arc-extinguishing reactor adjustment in medium-voltage power systems, based on superposition of two different non-industrial frequencies currents. Typical high-voltage electrical equipment can be used for the design. Investigation methods: mathematical modeling with software packages MATHCAD, MATLAB. Results: It is shown that the method proposed is sensitive enough to small changes in detuning of the capacitive earth fault currents. The authors have determined that currents could be input into the network through the winding of a conventional voltage transformer connected by open delta. The absolute methodical error of the compensation detuning measurements was calculated. It is caused by conductance in a zero sequence circuit. It was proved that typically absolute methodical error does not exceed 0,002. The paper introduces the algorithms of processing electrical quantities with frequencies of superimposed currents when the electric signal characterizing compensation detuning does not depend on absolute values of network total capacitive current.

Keywords

• ARC-extinguishing reactor
• measuring the detuning compensation
• currents of two frequencies
• voltage transformer
• methodical error