Ivo Chaves da Silva Junior

Parallel computing applied to the stochastic dynamic programming for long term operation planning of hydrothermal power systems

In this paper, parallel processing techniques are employed to improve the performance of the stochastic dynamic programming applied to the long term operation planning of electrical power system. The hydroelectric plants are grouped into energy equivalent reservoirs and the expected cost functions are modeled by a piecewise linear approximation, by means of the Convex Hull algorithm. In order to validate the proposed methodology, data from the Brazilian electrical power system is utilized.

Stochastic Dynamic Programming Applied to Hydrothermal Power Systems Operation Planning Based on the Convex Hull Algorithm

This paper presents a new approach for the expected cost-to-go functions modeling used in the stochastic dynamic programming (SDP) algorithm. The SDP technique is applied to the long-term operation planning of electrical power systems. Using state space discretization, the Convex Hull algorithm is used for constructing a series of hyperplanes that composes a convex set. These planes represent a piecewise linear approximation for the expected cost-to-go functions. The mean operational costs for using the proposed methodology were compared with those from the deterministic dual dynamic problem in a case study, considering a single inflow scenario. This sensitivity analysis shows the convergence of both methods and is used to determine the minimum discretization level. Additionally, the applicability of the proposed methodology for two hydroplants in a cascade is demonstrated. With proper adaptations, this work can be extended to a complete hydrothermal system.

Cuckoo Search Optimization technique applied to capacitor placement on distribution system problem

This paper presents an approach based on Cuckoo Search method for optimal capacitor placement in distribution systems. The Cuckoo Search (CS) algorithm is used to solve this mixed non linear integer optimization problem which aims to minimize losses in distribution systems. The proposed algorithm is evaluated using the IEEE 16-bus, IEEE 33-bus and IEEE 69-bus distributions systems. The results obtained show the effectiveness of the proposed technique.

Reconfiguração ótima de sistemas de distribuição para minimização de perdas de energia

Este artigo apresenta um algoritmo para a reconfiguracao otima de Sistemas de Distribuicao de Energia Eletrica (SDE), com o objetivo de minimizar a perda total de energia considerando diferentes niveis de carregamento. Trata-se de um problema de programacao nao linear inteira mista onde a variavel discreta e modelada como uma funcao continua. Como consequencia, o problema proposto e resolvido atraves de um algoritmo passo a passo, onde em cada passo e utilizado o Metodo Primal-Dual de Pontos Interiores. Os multiplicadores de Lagrange sao utilizados para compor o indice de sensibilidade no processo de reconfiguracao. O algoritmo proposto e testado em tres sistemas encontrados na literatura.

Modelo para o despacho de usinas individualizadas no planejamento hidrotérmico de médio prazo baseado em PNL

This paper presents a method to the hydrothermal dispatch using optimization techniques based on non linear programming techniques. To do so, the expected cost-to-go functions from a long term operation plannning strategic decision model are used. This decision model is based on stochastic dual dynamic programming and energy equivalent reservoirs. The proposed method considers a set of historical water inflow scenarios to the hydroelectric reservoirs. Those scenarios are used to simulate the long term operation planning to a given horizon. The results obtained from this disaggregation model (MIUH) are compared with those from the model officially adopted in the Brazilian power system, SUISHI-O. The latter is based on operation heuristics aiming at operating the reservoir maintaining the water storag e in similar levels, that is, trying to operate them in parallel.

Flower Pollination Algorithm Applied to the Economic Dispatch Problem with Multiple Fuels and Valve Point Effect

Due to the high importance of economic dispatch in planning and operating electric power systems, new methods have been researched to minimize the costs of power generation. To calculate these costs, the power generation of each thermal unit must be evaluated. When a thermal unit is modelled considering real world constraints, such as multiple fuels and valve point effect, traditional optimization methods are inefficient due to the nature of the cost function. This paper shows a study of a metaheuristic method, based on flower pollination to search for satisfactory results for economic dispatch. The results obtained are compared with results from other authors, with the purpose of evaluating how efficient the technique presented here is.

Security constraints for wind power operation

This paper presents a model to include a security constraint for wind power plant in a hydrothermal dispatch problem. The proposed Unit Commitment (UC) is an augmented problem to take into account different scenarios of wind speed during the day. The wind farms are represented by a linear model that the generations are considered proportional to the availability of wind. The proposed optimization model uses DC load flow in which transmission system constraints are included. The hydro plants are considered with constant productivity and the times of starting and stopping of thermal generation units are considered as well as ramp deviation. The results using a test system show that the operation of a hydrothermal system is strongly affected by the inclusion of wind farms.

A memetic algorithm for power system damping controllers design

This paper presents a hybrid algorithm for robust and coordinated design of power system stabilisers. Power system stabilisers are controllers installed on synchronous generators for excitation control in order to damp power system oscillations. The tuning procedure (gain and phase compensation stage) is cast as an optimisation problem which aims at maximising the damping coefficients in closed-loop operation. Robustness is dealt with by using multiple operating scenarios. For the optimisation problem solution, the bio-inspired Bat Algorithm is combined with the steepest descent method for local search capability enhancement. The proposed algorithm is applied to benchmark systems for validation.

Influence of Active Transmission Losses in the Operation of Thermoelectric Systems

The present paper analyses transmission systems operation bounds and active power losses influences on thermal Unit Commitment (UC). It makes use of sensitivity indexes based on information obtained from Lagrange multipliers associated with the decision variables. So, the thermal units are put in operation based on a previously obtained merit order. The results obtained through those simulations indicate a satisfactory efficiency of the proposed sensibility and shows the relevance of considering the power loss and operation bounds of the transmission systems in the UC problem.

Despacho Econômico com Zonas de Operação Proibidas através de Otimização Bioinspirada

Resumo O Despacho Econômico (DE) é um importante processo no planejamento e operação do sistema elét rico de potência, pois consiste no atendimento à demanda ao menor custo operacional possível. Este trabalho propõe a u tilização da metaheurística bioinspirada Bat Algorithm para solucionar o problema do despacho econômico descontínuo, devido à consideração da Zona de Operação Proibida (ZOP). Alg uns estudos de casos são apresentados para validar a me todologia proposta.