VFTO Calculation And Research Of VFTO Impact On Secondary Equipment

In power system, the isolating switch suit no-load bus bar is routine operation,the probability and frequency of operation is larger than other operation or ground fault and so on. Uh v substation operation on the isolating switch, isolating switch,contractor move very slowly. This slow motion to make contact between in break-brake operations would produce heavy breakdown for many times, will form the very fast transient over voltage, when the VFTO travels on a bus in encounter will be because of voltage transformer and voltage transformer high-voltage bus distributed capacitance and coupling between on the secondary cable conductor, and then enter the secondary equipment, form the conducted interference, VFTO interact with transient current produces the high frequency transient electromagnetic fields,in the form of radiation to the secondary equipment.Study of VFTO in addition to the actual measured both at home and abroad,mainly is the numerical simulation of the computer, also has a laboratory simulation experiments using physical model. Due to the advantages of using computer numerical simulation, such as flexible, low cost, save time, the calculation results good agreement with experimental results, the accuracy is satisfactory, so, in the fast transient phenomena study, computer simulation has become a wide scope of use, a method of powerful. Using EMTP software in this paper, its characteristic is to use current source and the resistance to replace components, power transmission network to establish the equivalent network node equation. For concentration of element parameters, approximate trapezoid formula to deal with; Distribution parameters with Bergson law to deal with. Through the study of the accurate modeling of substation, the input initial conditions, simulate the real substation of VFTO. Encountered when VFTO travels on the bus voltage transformers will be because of voltage transformer and high voltage bus bar between the distributed capacitance and coupling to the secondary cable conductor, and then enter the secondary equipment, form the conducted interference. In addition, VFTO interact with transient current produces the high frequency transient electromagnetic fields,in the form of radiation to the secondary equipment.In this paper, the conducted interference has carried on the calculation and analysis, obtained the final result, and are in good agreement with actual situation.Exploratory put forward the preventive measures against the interference. At the same time, preliminary illustrates the harm of radiated interference.