Study On The Prevention Measures Of TV Fuses Blowing In Medium Voltage Distribution Network

There are generally the electromagnetic voltage transformer(TV) in the substation bus bar of the ungrounded medium voltage distribution network. It cannot make the power grid stable when TV primary fuses abnormal blowing accident frequently occur.Therefore, it is very necessary to study the main cause and the influence factors of TV primary fuses blowing, the advantages and disadvantages of several existing prevention measures and new effective prevention measure, which has significant engineering value and practical significance.Through the study found that the main cause of TV primary fuses blowing even explosion are ferroresonance and low frequency nonlinear oscillation. This paper makes a simulation model of 10 kV power distribution system by ATP-EMTP. And it makes the simulation analysis on the four main influence factors of TV primary fuses blowing which are the total length of bus feeder line, TV excitation characteristic, TV primary DC resistance and the single-phase grounding resistance. It gets the general rules that these factors have influence on TV primary voltage, current and the resonance state.It makes the introduction of the circuit principle, the simulation analysis and the comprehensive comparison of several existing measures for preventing TV primary fuses blowing,and summarizes the advantages and disadvantages of them. The serious defect of current measures still existed is been found out. Thus a new prevention measure is been proposed which is TV primary neutral point grounded by single phase in parallel with harmonic elimination device or linear resistance, and it makes the simulation analysis on its measurement error correct and harmonic elimination effect. Finally, it is carried out by high pressure simulation experiment which is the test verification of various prevention measures and new prevention measure proposed in the paper.When several bus bar TV in parallel operation, it makes the simulation analysis on the prevention measures of TV primary fuses blowing and comes to the conclusion. It analysis on the different influence on harmonic elimination effect, and discusses the number of the prevention measures installed on bus bar TV.