In our days with the closing of the base power plants, and with the fossil power sources getting more expensive the industry follows harder and harder the growing energy demand.
One solution to the problem to the energy demand is to expand the 120(132) kV distribution network and the usage of renewable power sources in the power distribution. This requires the modification of the distritution network: splitting some sections of the power line, in which we have to make the right calculations on the new network modification in case of fault event.
In this work my task was to analyse a 120(132) kV power line - which starts from a windfarm substation as an overhead line, then ends with a short cable to the high voltage distribution substation – as of what kind of currents occur on the overhead line during a fault event.
For that first I had to determine the electrical paramters of the power lines and to calculate the impedance of the two substations. After determining the parameters I consulted with my professional consultant to calculate the fault currents on a 1PH-N fault. First I had to draw the right replacement image of the network, then calculate the zero sequence current from which I could calculate the phase fault current. Because my task was to determine the current-diagram, and the current equation I had to split up the overhead line to two parts from the fault location. In that case separating the overhead line to an x and l-x component and with the changing of x parameter we get different fault current results. With these calculations I determined the fault current equation and with chosing scale-fine the x parameter I drawed the current-diagram.
In the next part of the work I built a detailed model of my network with the EMTP-ATP simulating program, and with the help of it I could compare the calculated and simulated results.
With the highest current taking into account from the current- and the protective conductor catalogs, or the standard we can determine that the conductors was a good choice in the case of short-curcuit stability or we have to chose another conductor.