A Development of Equivalent Grid Harmonic Model for Integration of Offshore WPPs: A case study for Northwest Turkey

The territorial water in northwest Turkey is rich in terms of high wind speed. There is a significant number of sites for the potential large-scale offshore wind power plants (OWPPs) in this region. The integration of large scale OWPPs may arise serious harmonic stability problems in transmission grids. To analyze grid harmonic stability and comply with the grid code requirements, it is crucial to construct harmonic models for the transmission grids. In large transmission systems, the development of an exact harmonic model needs much effort and it is not required in most cases. The harmonic characteristics of grids can be revealed by equivalent harmonic models which identify critical harmonic resonance points of the grid. In this paper, an equivalent harmonic model of the Turkish power grid has been developed for the harmonic resonance assessment studies of the potential OWPP located in the Kiyikoy of the Trakya region. For the equivalent model development studies, the transmission grid in Trakya region has been modelled in detail and harmonic impedance characteristics for the rest of the grid beyond Istanbul and Dardanel Bosphouruses has been determined using frequency sweep analyzes. In the last stage, the grid harmonic model has been downgraded into a three-bus system and the harmonic bus impedance matrix has been built up for harmonic resonance analyzes. The equivalent model development and analysis studies have been performed using Digsilent PowerFactory software.