Peducing the frequency of switching overvoltage in generator networks

THE PURPOSE of the study is to study the problem of switching overvoltages in 10 kV generator networks. Using the Matlab Simulink package, create a model of common auxiliaries of a 10/0.4 kV power station, calculate the overvoltage at different sections of the current, evaluate the effect of vacuum switches on each other, evaluate the effectiveness of nonlinear overstrain limiters, with parallel switching.

THE SCIENTIFIC SIGNIFICANCE consists in obtaining a method for calculating transients with simultaneous switching of several switches. THE PRACTICAL SIGNIFICANCE lies in the possibility of using the resulting model for a more accurate selection of protective equipment.

METHODS. To create a model of common auxiliaries of 10/0.4 kV and the calculations of transition processes, it used a Matlab Simulink package. RESULTS. The article discusses switching overvoltages in their own needs of 10/0.4 kV. The influence of parallel switching of vacuum circuit breakers on the increase in the multiplicity of overvoltages is estimated. The influence of the specific energy intensity of nonlinear surge limiters on the multiplicity of overvoltages was also evaluated.

CONCLUSION. This model showed that the parallel switching of two vacuum circuit breakers can increase the frequency of overvoltage by 20-40 %, which can lead to an increase in wear of both insulation of the protected equipment and the probability of re-breakdown in a vacuum chamber. Moreover, the higher the current cut, the higher the increase in the frequency of the overstrain, the multiplicity will also increase if the shutdown time between the switches is reduced. The main means of protection against switching overvoltages is a non -linear overstrain limiter, but when they are selected, the nominal working voltage is primarily taken into account, which leads to the fact that the increase in the frequency of overstrain from parallel switching can level the effectiveness of a nonlinear limiter.

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