Examenspresentation av Mattias Fransson och Erik Johansson

Conducted at Ringhals supervised by Sofia Johansson, Mikael Nilsson and Magnus Knutsson

Opponent: Gabriel Hassellöf

Abstract
As of the 16th of May, two offshore wind power plants (WPPs) located outside the coast of Halland was granted approval from the Swedish government. The combined installed capacity of the WPPs is expected to be over 1500 MW, and both prospectors are planning to connect to the same transmission lines that Ringhals power plant are utilizing. This report investigates possible electrical phenomena inherent to large scale WPPs that may affect the operation of a close by thermal power plant. A literature review was conducted which indicated subjects of interest, four key subjects were chosen to study further, namely harmonic emission, sub-synchronous oscillations, behavior during fault and abnormal grid states, and finally, inter-area oscillations.

Through further literature analysis, the findings showed that harmonic emission should be manageable, while sub-synchronous oscillations could pose an issue given a situation of weakened grid and poor damping techniques. It was also found that there is a minor risk that an introduction of a WPP could increase the risk of inter-area oscillation. Dynamic phenomena was studied though extensive simulations in PSS/E, the simulations indicate that the grid, in its current condition should be able to sustain the impact of a sudden disconnection of a WPP without serious voltage deviations, and that the critical fault clearing times of the generators at Ringhals could either increase or decrease from an introduction of a WPP, depending on its fault behavior.

Welcome!

Mattias, Erik & Peiyuan