Research On Electronic Voltage Transformer Based On Capacitive Voltage Divider

The voltage transformer is a very important device, and it is very useful in electric energy measuring, automation and relay protection. Along with the development of power system, there have three stages in its development: electromagnetic power transducer (PT), capacitive voltage transformer, and electronic voltage transformer (EVT) .As one kind of the voltage transformer, digital voltage transformer has the strongpoints such as no saturation resonance, high precision, and wide frequency band. At the same time, it also has the strongpoints as brief structure and low cost. Therefore, the study for digital voltage transformer has achieved great progress, and it has very good realization foreground.In this paper, the author designs the capacitor divider, which is a common voltage transducer. The capacitor divider is used commonly in the measuring of high voltage, and it has been used in the capacitor voltage transformer. So there are much experience in the using of capacitor divider. But the capacitor divider in digital voltage transformer is different from the one in capacitor voltage transformer ,it has its own particularity .In this paper ,the author particularly studies the capacitor divider steady state characteristics in voltage transmission ,and analysis the transient characteristics. In the end, the author validates those analyses through simulating and trail, and concludes the technique of improving the stabilization and transient characteristics.As an important part of digital voltage transformer, the author also studies the insulation between the high voltage side and the low voltage side in this paper. First, the author compares the exiting means and analyzes the strong points and weaknesses, and then advices a method based on photoelectric isolation .Finally, the author designs a circuit based on this method, and do some trails for this circuit.In the end of this paper, the author discusses the signal processing and direct current power supply system. In this part, the author analyses the exiting means, and then chooses the appropriate power supply technique for this design.