PRORAČUN SKLOPNIH PRENAPONA ZA SLUČAJ METALNOG TROFAZNOG KRATKOG SPOJA NA SN-IZVODU SA PRIKLЈUČENIM INDUKCIONIM I/ILI SINHRONIM GENERATORIMA

Abstract

The paper presents the procedure for calculating the switching overvoltage on the supplying circuit breaker of the MV cable feeder to which induction and/or synchronous generators are connected during a bolted three-phase short circuit. When a fault occurs, the feeder is disconnected by a circuit breaker at the beginning of the feeder. After the set delay time has expired, since island operation is not allowed, the connected distributed generators will also be switched off. It is shown that, during the period when the grid is off and the generators are on, the overvoltage factor reaches a value between 2.2 and 2.5, depending on the type of generator and the connection location. The individual responses of the distribution network and the mentioned types of distributed generators in case of failure are known and they differ significantly from each other. By using the superposition theorem, it is shown how to calculate the switching overvoltage, with the elementary use of a computer.