Janis Gerhards

A model for maximizing the profit of a HPP cascade considering hydraulic link via reservoirs

At the conditions of market relationships and economic and financial independence of power company (GENCO), these are guided by the principle of achieving maximum efficiency in their actions. For a hypothetical cascade of hydropower plants (HPPs) consisting of three HPPs, a problem formulation aimed at optimum loading of each individual HPP is used, ensuring maximum profit for the whole cascade from the sales of the generated electric power at the day-ahead market. The structural diagram of a problem solution algorithm is presented, which uses the method of statistical modeling. The results of the modeling of cascade operating regime are illustrated graphically. The results have been used to calculate the summary profit of the HPP cascade. The structural diagram of the algorithm can be basically used for an arbitrary mix of HPPs in the cascade, with a weekly regulation cycle.

Optimization of power reserves in market conditions

The optimization problem of the power reserves in the electric power system (EPS) for the purpose of the operation reliability increase is considered. The analytical expression of the power reserve optimum price determination for the electric power concrete producer is given. The considered strategy of the power reserve formation for the EPS is realized on the base of Matlab program. The results of the total power reserve optimization for the EPS test diagram are presented.

Probabilistic reduction of generation in adequacy calculation

Problems of a generation system reduction in calculations of a power system (PS) adequacy are considered. The attention is mostly focused on mathematical models, based on the binominal and Poisson distributions, Poisson failure flows and characteristic functions of random variables. The reduction procedures result in the disturbance of integer number of units in operation. It was shown that it is appropriate to carry out rounding-off and following correction of probabilistic indices using the criteria of capacities at hand and expected values of generation tripped equality. As a result of models comparison the preference is made for models, based on the binominal and Poisson distributions. In the case of huge PS units diversification the combined distribution is assumed to be used, emphasizing units with the highest capacity and equivalent the rest, in order to perform adjusted calculations by means of computer.

Modification of supplied demand algorithm for generation adequacy indices calculations

In order to determine the indicators of the adequacy of meshed united electric power systems (EPSs), an algorithm of accelerated calculations is proposed, which is based on probabilistic equivalenting of intersystem power flows at the conditions of probabilistic demand and supply from adjacent EPSs. The conditions are considered and the fluctuant character is pointed out of the convergence of the iteration process of the formation of the resulting indicators of the nodal power imbalances. The recurrent relation is reflected algorithmically. In order to improve the convergence of the iteration process, a modification of the guaranteed demand algorithm is proposed, which takes into account the fluctuation character of the convergence by means of parabolic interpolation of the mathematical expectation of the power flow. The calculation procedure is illustrated on the basis of a three-node closed circuit of a united EPS. The algorithm has been appraised on the basis of a 42-node circuit of a meshed EPS. Ways for further refinement of the algorithm are proposed.

Control actions based nonlinear objective function for robust calculations of electrical power system security

Electrical power system (EPS) security analysis is a part of EPS reliability analysis. It consists in multiple load flow calculations, when one or several EPS elements are assumed to fail. General approach for load flow calculation (LFC) problem is to use iterative fast calculating AC load flow technique, for instance fast-decoupled power flow. The key problem associates with robustness of LFC routine. Indeed, if several elements fail simultaneously, resulting load flow could be unfeasible. In this case, LFC routine will diverge. Nonlinear programming based (NLP) approach for LFC problem allow increasing the robustness of LFC routine. This paper presents a modification of typical NLP technique, which increases robustness and accuracy of LFC procedure in the framework of security analysis.