Probabilistic harmonic power flow for assessing waveform distortions in distribution systems with wind embedded generation

Nowadays the need for more flexible electric systems, the changing in the regulatory and economic scenarios, the importance of harnessing energy savings and minimising environmental impact have been providing the impetus for the development of a new distribution system into which embedded generation with wind farms is predicted to play a key role. While several advantages result from wind farms presence in distribution systems (reduction of power losses, enlargement of the time horizon for distribution company investments aimed to the network reinforcement, and so on), they can involve technical problems among which the ones related to power quality have received a great interest in the most recent relevant literature. In this paper the problem of calculation of the waveform distortions in distribution systems with wind farms is considered. Taking into account that unavoidable uncertainties affect the modelling input data, a probabilistic harmonic power flow (PHPF) is proposed which properly include the randomness linked to the wind farm presence. The PHPF permits the evaluation of the percentile and maximum values of the probability density functions of the waveform distortion indices that are nowadays the statistical measures of interest in the most recent international standards and recommendations. Numerical applications on a 32-bus test system are also shown