Insulation Coordination Analysis Of Low Voltage Ride Through Test Device In High-altitude Area

LVRT simulate voltage fault of grid point(test point) by cutting reactor. As a result of the strong arcing ability of vacuum circuit breaker, cutting reactor can cause high amplitude, high frequency overvoltage in experimental circuit, it is likely to cause damage to equipment insulation, at the same time, low pressure and thin air of high altitude experimental environment will bring greater difficulty to equipment insulation. In order to achieve the goal of safe and stable operation, need to analyze the operating overvoltage and suppressed, at the same time improve the insulation of the electrical equipment itself.First, in this thesis, based on a LVRT of the Yellow River in Qinghai province in 3500 m, analysis theory and simulation for the chopping overvoltage and rekindle overvoltage according to the mechanism of overvoltage. Conclude a result: when chopping value is 5A~10A, test point overvoltage amplitude for 1.87 p.u.~3.92 p.u.; when chopping value is sure, overvoltage amplitude is least when phase angle is 90°; for rekindle overvoltage caused by rekindle, influence of different rekindle time on single-phase rekindle overvoltage and two-phase overvoltage is researched, when rekindle after circuit breaker broken 6ms, overvoltage amplitude is largest.Secondly, analysis the experimental conditions, repetition overvoltage simulation, compare the simulation results with the measured wave recorded, to validate the correctness of the simulation results. And correct the simulation of overvoltage amplitude in high altitude.Then, overvoltage suppression measures were studied. Summed up the RC absorption equipment consisted of 0.1?F capacitance and 100? resistance parallel on both sides of paralleling reactor can effectively restrain overvoltage amplitude and frequency. The effect on overvoltage gradient inhibitory by lightning arrester is not obvious, can be used as a backup protection device of RC absorption equipment, based on a 1100 k V ZnO arrester as an example, determine threshold voltage value of the arrester through field simulation, and through the analysis of ZnO plate microstructure, the build method of transient circuit model of lightning arrester was proposed, compared with the experimental results, prove the validity of the lightning arrester equivalent model. Finally the method of equivalent model is used on 35 kV combined arrester, install it on the reactor, concluded compare its protection effect with only install RC absorption equipment.At last, reactor is large capacity perceptual element of experimental circuits, carrying large overvoltage, so it need to improve the insulation level. For external insulation of reactor, analyzes the structure and the environmental factors affecting reactor external insulation level, including adding insulation board between wire tap, tap shape, insulator parameters under high altitude environment, distance between reactor and surrounding equipment. For internal insulation, reactor internal temperature rise of short-circuit flow reactor was analyzed.