SIMULATION OF SWITCHING OVERVOLTAGES IN POWER SUPPLY SYSTEMS OF METALLURGICAL PLANTS

 The article describes the development carried out within framework of the state program, which provides development of industrial  enterprises, including enterprises of metallurgical cycle. Such enterprises are complex plants and associations of vario us scales whose  production has important strategic significance. For reliable functioning of metallurgical enterprises, the adequate power supply system  with high energy efficiency and minimum possible power consumption is required. Most receivers of metallurgical production belong  to the first category of reliability of electricity supply that makes  high demands on their power systems. The power supply systems of  metallurgical companies are considered. It is shown that the power  supply system may be affected by various negative factors, including the switching overvoltages. Such overvoltages can have high frequency character and occur when triggered vacuum swit ches. Their  appearance is caused by the arc interruption mechanism in vacu um  (arc reignition, current chopping, voltage escalation). Overvoltages  reduce level of reliability of power supply systems that can lead to  long outage of responsible consumers. Most vulnerable to overvoltages elements of power supply systems are electric motors whose  isolation has the smallest margin of electric strength. Typical means  of protection (spark-gapped arresters, metal-oxide surge arresters,  spark gaps) are ineffective for limiting the overvoltages with high  frequency character. To limit overvoltages of this kind protective RC  circuits are increa singly used. However, their application must be accompanied by fairly accurate simulation, because the wrong choice  of their parameters can lead to deterioration of switching process. All this causes importance of the problem of choosing the optimal  parameters of protective RC circuits and their connection schemes.  The typical power supply scheme was identified and simulation of  the switching overvoltages arising in the similar scheme was carried  out. MathLab package was applied to build the model of a fragment  of the power supply system. Du ring crea tion of the model there were  used already known provisions and provisions for the first time offered by the authors that provide the larger accuracy to the mo del.  The received results are presented in the form of oscillograms and  comparison of experimental and calculated data was performed. The  relative error of the results was less than 5  %. The recommendations  for the construction of rational power supply systems of metallurgical companies allowing to reduce negative disturbances, acting on  the such systems are given.

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