Effect of renewable energies, especially PV on the LV distribution grid

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Dr. Farkas Csaba
Department of Electric Power Engineering

When the electric power system was built in the 20th century, it was optimized for the transport of electricity produced by fossil and nuclear power plants. These power plants operate with high performances, and each one can handle a lot of consumers (e.g. one or more cities). Therefore, classically there was a determined direction of energy flow, from the power plants to the consumers. The electricity grid was built up with this in mind, and today most of the devices on the network support this one-way energy flow.

However, having realized that the availability of these fuels is finite and the operation of conventional power plants (especially thermal power plants) is highly polluting, s need has appeared for new solutions in the field of electricity generation. Fortunately, we have a number of other sources of energy that can replace our currently used energy sources, which are far more environmentally friendly, and their long-term availability can be viewed as endless. These are commonly referred to as renewable energy sources.

Due to the increasing shortage of our classical energy sources, we are increasingly focusing on renewable electricity generation. In particular, since 2010, renewable energy generators have started to grow rapidly and now 10% of the world's electricity generation is recovered by renewable energy producers. At the monent, the most rapidly spreading methods are solar cells, utilizing the energy of our Sun.

However, the current power system is not ready to support these renewable energy generation methods. At the time of its construction, the main techniques of energy production were nuclear and thermal power plants, and the network was optimized to support that type of production as well.

Therefore, the spreading of renewable energy sources, especially solar power plants, requires the rethinking and rebuilding of the network. This is not a small task, for which to complete, we need to know the exact effects of renewables on the electric network.

In the first half of my paper, I try to summarize these effects. I will go through the impacts of each renewable energy resource on the electricity grid, with my main focus being the systemic and local effects of solar cells.

After that I try to present these effects through a concrete example. I am going to explore and analyze a real problem in one of Hungary’s power company’s (NKM Áramhálózati Kft) network.

To do this, I will prepare a model of the network section, using a network modeling program and by running various simulations, I will examine the conditions before and after installation of the solar cell in the district.

Finally, after analyzing the differences and finding the source of the problem, I try to determine what changes should be made on the network to ensure stable operation.


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