Power transformer losses are important to estimate and measure both for producers and for utilities. The question becomes even more critical when the power transformer is carrying load currents with harmonics. It is important to be able to calculate the load losses accurately in order to be able to estimate hot spot temperatures and total losses during operation. Finite Element methods are well known and well proven during the last 40 years. Producers usually have proprietary programs that are developed and used in house. These programs are restricted and are not available for academic research. In this paper, a parametric model of a power transformer is made in COMSOL so that important dimensions of transformers can be entered to yield realistic loss calculations.

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The paper proposes method and algorithm for obtaining the maximum transmitted power limit in the power system under the voltage stability conditions in case of emergency outages of its elements - power lines and generating sets. The method is based on the analysis of the exaggerated states of the system created by increasing the values of the power sources (generators of power plants). The model of system states in extreme modes is described in the form of “extreme transmitted power – generating power values” relationships. The efficiency of the method is investigated on IEEE test schemes and the real Azerenergy system scheme. A comparison of the proposed method results with the evaluation of the critical conditions on the basis of trained neural network is presented.

Abstract. At present among renewable sources the wind and solar plants have the most significant portion of power generation. Randomly changing and intermittent nature of this power leads to the stochasticity of the power grid mode, estimation of parameters of which requires application of probabilistic modeling. In the paper it is proposed an advanced algorithm of probabilistic load flow based on the development of two-point estimation method, the efficiency of which is confirmed on the basis of computational experiments and comparative analysis of the Monte Carlo simulation results. Calculations and analysis of the modeling results were carried out on standard 14-nodal scheme of IEEE and real electrical network of "Azerenerji" Grid.

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