Elektroenergetski sistemi (Slovene)

Energy markets within the power industry deregulation pushed operation of electric power systems (EPS) towards the limits, which may result in stability problems an in degradation of electric energy supply quality. Angle as well as voltage stability problems are highly nonlinear phenomena with no elegant solution. Power system control needs adequate methods not only for load management, frequency and voltage regulation but also for improving angle and voltage stability. Improved tools for security margins estimation are needed along with the assessment of adequate measures. The laboratory group focused its research activity on the simple methods of voltage stability assessment, decentralized secondary voltage control and power system security with an original approach. Procedures of fast estimation of a transformer state after a fault are developed. Solution to the mentioned problems is tightly connected to the available active and reactive power reserves, which are difficult to assure at all times for minimum cost. The research group offered new solutions to this problem, especially for mixed hydro- thermal power systems taking into account their local dispersion. Demand side management is one of important points in control of disturbances and cost minimization within the power system states. It relies on load reduction and voltage control at the consumers. The research group pursues an approach to load control via voltage regulation by under load tap changers using neural networks. A wide program of measurements in the distribution network is currently under way. Minimum cost operation of hydro- thermal power systems requires adequate models for fast estimation of bidding strategy in the energy market taking into account the market participants behavior. The group is developing an efficient model of hydro power plant scheduling based on artificial neural networks and combined methods of evolution and classical optimization. The models for power system optimization could be used within the integrated power system planing, which is lacking efficient methods. Stochastic nature of loads and unpredictability of energy market have to be observed in the model. The research group develops the models and algorithms for integrated power system planning under uncertainties.