The central part of the graduation thesis is related to the reactive power compensation. The
emphasis is mainly on collecting the data on the reactive power and their influence on the
change of cos in the substation RTP Koper in the case we would monitor the level of the
reactive power compensation. Therefore, we have also discussed an actual case of the reactive power compensation on the consumer with extremely poor cos, actual economic justification ,of the investment, and the time of investment´s recovery. In our case, the latter will be especially interesting.
The question of the reactive power compensation is especially highlighted by opening up the
electricity market, since the bill for the electricity encompasses only working energy and the
tip. Therefore, the electricity supplier is not concerned with the reactive power. Network
operator, who is also responsible for connecting new consumers to the network, deals with the reactive power. In the thesis, I have therefore discussed an actual example in the substation ,RTP Koper, where I have analysed the existing situation. Based on the measurements and calculation, I came to a conclusion that currently in the substation RTP Koper there is no need for the reactive power compensation, since the current cos is better than 0.95. I have also ,calculated the situation for 2020 when, given the foreseen annual growth of the electricity ,consumption, which is 2.3 % per year, the consumption in the substation RTP Koper will rise so much that the two current transformers of 31.5MW will have to be replaced by the two transformers of 40MW. What will happen to the reactive power or cos? With the same ratio of the working and reactive power the cos will remain the same, only the amount of the reactive power will increase. In that period, it would be reasonably to re-examine the case, and then maybe install the compensation device with a power of 3.0MVAr per phase. I have encountered the same results in the study EIMV REDOS 2020 for Slovenian Istria and the coast with hinterland.
In conclusion, I shall say that the consumers powered from the substation RTP Koper have a
good compensation. That can be seen from the data, since they have a very good cos.
However, there are some exceptions with a very poor cos. Fortunately, these consumers
have a very small consumption of the working energy (they are relatively small). Therefore,
their impact on the total cos in the substation RTP Koper is negligible. I have also made a
calculation of what would happen to the total cos in the substation RTP Koper if all the
consumers with the cos worse than 0.95 compensated it to this value. According to the
result the cos would improve for 0.005, meaning that it would increase from the current
0.975 to 0.98. I have also calculated what would happen if all the eligible consumers with the cos better than 0.95 compensated it only up to this value. In this case, the total cos in the substation RTP Koper would deteriorate from the current 0.975 to 0.961, which is still solidly and within the regulations. In conclusion, I shall mention the case of the eligible consumer with the cos = 0.69 for whom I have calculated what would happen if they installed the compensation device. The result of the calculation revealed that the compensation device would pay back in less than a year, and in each of the following years they would save approximately EUR23,500 with the network costs.
From the above, it is evident that in the field of the reactive power much more can be done. However, prior any intervention it must be very well considered what and how we will deal with things, what kind of compensation will be installed, and of what kind of power should the device be. Regardless of the economic justification, the matter must also be viewed from the technical perspective. That means that, in addition to the reactive power compensation, a great emphasis must be given to the harmonic components that influence the quality of electricity. With an increasing number of power electronic components and other network polluters, that has already become a great problem that will be increased in the future.