Statistical Impact Evaluation of Stochastic Parameters Enhancing Solar Power Inherent Smoothing

The characteristic variability of solar power brings potential threats to power system frequency stability by introducing short-term power fluctuations. A nationwide virtual PV (photovoltaic) system of 14 locations in Finland with interplant distances between 10 km to 1065 km has been analyzed at 1 Hz resolution by introducing stochastic variables i.e. power fluctuation, maximum power fluctuation and smoothing potential factor. The paper presents a multifold smoothing analysis based on geographical dispersion, ensemble size, temporal resolutions and interplant distances of PV plants. Empirical expressions are proposed using regression analysis, which represents a decay of smoothing potential factor for a decreasing time resolution. Aggregated strength of maximum power fluctuation of $N$ number of PV plants decreases by a converging factor 1/-N and an ensemble of 14 PV plants follows the strict ramp rate limits for 97.5% of the total production time. Spatial correlation w.r.t interplant distances is also focused.