Study On Measurement Method Of Off Tuning Degree In The Distribution Network Of Neutral Resonant Grounding

With the further reconstruction of distribution network automation, neutral resonant grounding has been one of important method to suppress the one-phase grounding fault current and to clear the earth fault in urban distribution network. As the subject of dissertation for master degree, 搕he Study on Measurement Method of Off Tuning Degree in the Distribution Network of Neutral Resonant Grounding? has important practical value.However, there exist some defects to the present resonant regulation niethod, a new method of resonant regulation based on injecting current is presented in this paper. Various frequency constant current is injected to second side of PT (potential transformer) which the petersen coil is the first side. Petersen coil tuning system is implemented, which is based on measuring the system resonance frequency. This principle is not affected by syctem operation. It has high precision and high reliability.In measuring system, a band elimination filter (BEF) is designed to eliminate the interference of noise signal, which is caused by the nature displacement voltage and is higher by many times than the measured volt4e. The BEE抯 output is zero at 50Hz and is constant on amplitude and phase at other frequencies.A device for measuring off tuning degree based on the principle above-mentioned is developed, which have passed the practical test through measurement in Fuyang power station in Hebei province. Operational experience shows that this method is effective. If it operates with the microcomputer control system, automatic tracking resonant regulation will be obtained.