UTICAJ SERIJSKOG REAKTORA ZA OGRANIČAVANjE STRUJA KRATKOG SPOJA NA PERFORMANSE ELEKTROENERGETSKOG SISTEMA

Abstract

Adding new power power plants and generating units into a certain power system may lead to a significant increase in the system short circuit levels. One of the possible solutions for preventing outlimiting pre-defined short circuit values is implementation of a series reactor (SR) into the system. The need to decrease the short circuit level while maintaining voltage drops and overall system losses in allowed limits is the main factor in choosing the right dimension of this SR. As a result of implementation of the adequate SR into the system, it becomes possible to keep the existing breakers instead of replacing them with circuit breaker with higher levels of breaking current. Replacement of the existing equipment (circuit breaker and auxiliary equipment) is required in case of omitting the use of SR. However, implementing SR in the system may also have negative impact on the elements of the power system. It can lead to the increase in the levels of temporary and switching overvoltages and/or increase of the amplitude of transient recovery voltage and rate of rise of recovery voltage on the existing circuit breakers and in some cases may even lead to violation of the limits required by international standards/grid code. Main objective of this paperwork is analysing the effects which might occur after the implementation of a series reactor in the existing 400kV power system. Model is formed so that it includes detailed models of the elements in the system at least two buses away from the observed point of coupling. Simulations are performed using PSCAD/EMTDC, a state-of-art software analysis tool for this kind of studies. Results of the simulations show the impact of the series reactor on the transient recovery voltage of the nearest 400kV circuit breaker, comparisson of overvoltages values which are the result of the switching operations with withstand limits provided by IEC Standard and suggestion of mitigation measures, if needed.