Voltage control methods in the MV grid with a large share of PV

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Dr. Farkas Csaba
Department of Electric Power Engineering

The traditional distribution grid is operated radially and has passive consumers that only draw power from the grid but feed nothing back and as a result of this the line voltage constantly drops from the feeder point to the breaking point. The previously mentioned process defined the voltage taps of the MV/LV transformers. Nowadays more and more solar power plants are implemented into the grid and in the future it seems that it will grow further, so the traditional voltage regulation methods that are currently used in distribution systems need major modifications if we are to uphold the proper quality of electricity supply. In the beginning of my thesis I presented the possible effects of the increasing solar power implementation on the MV distribution grid, furthermore the available regularization methods. In order to accomplish this research, I installed solar panels with different amount of nominal power in the simulation model of the long range MV overhead line grid, which is close to the Perkupa 22 kV station. After the installation of the solar panels I analysed the voltage change in some nodes of the grid compared to the previous status without solar power generation.

From the presented voltage regulation methods first I made simulations in order to analyse the voltage dependent reactive power regulation. I created the simulation with DIgSILENT PowerFactory and the voltage dependent reactive power regulation was carried out with the help of the Python program code. Based on the results of the executed research I found out that in case of high amount of solar power generation it would be reasonable to use further voltage regulation methods besides the application of voltage dependent reactive power regulation.

In the next phase of my thesis I examined the application of the series line voltage regulation together with the voltage dependent reactive power regulation. In the simulation I configured a series line voltage regulator which is similar to the ABB Line Voltage Regulator. At the end of my thesis based on the results of the research I demonstrated that it would be reasonable to use the two regulation methods together.


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