The simultaneity of power produced by wind turbines (WTs) as a function of total power of the wind farm (WF) is investigated in the first part of this paper, and subsequently, a probabilistic approach to model the simultaneity of WT power in a WF is proposed. The investigation of the WT power simultaneity is carried out by analyzing measurement data sets. In this regard, the influence of the following aspects on the simultaneity of WT power is investigated and described: the number of WTs, the spatial arrangement of WTs, and the averaging timeframe of the WT power. Afterwards, with the aid of the investigation results, a nonsequential Monte Carlo method is proposed to generate a synthetic set of the WT power with a realistic simultaneity. The synthetic set of the WT power can be applied as input data for further nonsequential Monte Carlo simulations like reliability assessment or power quality evaluation.Index Terms-averaging timeframe, simultaneity, Monte Carlo simulations, spatial arrangement, wind turbine power. NOMENCLATUREc Modification constant for the WT power pdf d avg Average distance of WTs from the WF center k Shape parameter m Number of WTs which are out of operation m 0 A given integer value for m n Number of WTs n n Redefined n P W T i Average power produced by the i th WT during a timeframe, in % P W T max Upper bound for the modified weibull distribution, in % P WF Average power produced by the WF during a timeframe, in % P WF 0 A given value for P WF , in % P WF 0 n Redefined P WF 0 X WF c x-coordinate of the WF center X W T i x-coordinate of the i th WT Y WF c y-coordinate of the WF center Y W T i y-coordinate of the i th WT ΔP WF Tolerance band for P WF , in % Δt Averaging timeframe λ Scale parameter K. Malekian is with the

Abstract. This paper shows the results of the analysis of the measured power values of photovoltaic and wind power plants in the proximity of several electrical substations. The aim is to receive an impression of the frequency, time and duration of very low and very high simultaneous feed-ins of photovoltaic and wind power plants. Therefore, the data of nine electrical substations is analysed. Besides typical statistical values, a comprehensive analysis on the occurrence, extent, distribution, time and duration of the totalized photovoltaic and wind power feed-in is made. The results show that the occurrence of extreme totalized photovoltaic and wind power feed-in basically depends on the relation r of the installed nominal power of both plant types. For an optimal relation r, there are only a few or even almost no very high feed-ins and the number of very small feed-ins can be reduced by balancing the relation r to about 0.5.