AN INTEGRATED DISPATCH MODEL OF GAS SUPPLY AND THERMOELECTRIC SYSTEMS Oderson Dias de Mello and Takaaki Ohishi State University of Campinas Campinas, Brazil {oderson@cose, taka@densis}.fee.unicamp.br Abstract – This paper presents an integrated dispatch model of a natural gas supply system and a gas power plants system. The proposed model integrates the opera- tion of the power plant system with the operation of the natural gas pipeline network. The methodology decom- poses the problem in two models. The first one corre- sponds to an economic dispatch model and the second one simulates the pipeline network operation. The proposed approach was applied to an example of six power plants supplied by a natural gas system. Keywords: Natural Gas, Economic Dispatch, Pipe- lines, Power Generation 1 INTRODUCTION Since the early 1970’s crude oil crisis and the devel- opment of combined-cycle power plants, the natural gas (NG) becomes a strategic and economically competitive energy resource, and extensive pipeline networks were constructed at U.S.A., Russia and Europe. During last 50 years, the world energy consumption supplied by natu- ral gas expanded from 9% to 25%. This increase on the natural gas consumption should be maintained due the great number of unexplored natural gas reserves and its low environmental impact compared to other fossil fuel. Nowadays, only 20% of natural gas reserves are ex- plored against 50% of crude oil reserves. In the last decades, several papers have been pub- lished about natural gas transmission and/or power generation. Goldberg in [1] applied techniques con- nected with artificial intelligence and genetics to the problem of computer-based control of gas pipeline sys- tems. Wolf and Smeers developed an algorithm to solve the problem of the optimal dimensioning of a gas trans- mission network [2]. In [3], Venkataramanan et al pre- sented a technique that can be used to optimize the fuel consumption in the gas pipeline operation. A model to compute the maximum power generation of a combined- cycle power plants system is presented by Munoz, Redondo and Ruiz in [4]. In [5], the gas distribution pipeline network operation problem was formulated as a cost minimization problem subject to nonlinear flow- pressure relations, material balance equations, and pres- sure bounds. The solution method proposed was tested using the Belgium gas network. The NG pipeline network operation must comply with the natural gas consumption due its low storage capac- ity. As the electric power plant is one of the major natu- ral gas consumers, there is a close interaction between the NG power plant operation and the gas supply sys- tem operation. The dispatch of the NG power plants affects the NG flows in the pipelines, and, by the other side, the pipeline network operational requirements can impose limits on power plant generation. In this context (Figure 1), the models that integrate the operation of these two systems are important for an economic and secure planning and operation. Figure 1: Relation between the NG transmission system and the thermoelectric system operation. This paper proposes a model that considers a set of NG power plants supplied by a gas pipeline supply sys- tem. The objective is to minimize the costs of power generation, NG production and/or acquisition, and transmission. System requirements, such as electric load demand, power generation limits, NG flow pressure limits at pipeline network and take-or-pay contracts are repre- sented in the formulation. The paper is organized as follows. The formulation of the problem is presented in Section 2. Section 3 dis- + Legend: NG non-electrical consumption NG production/import NG pipeline Power production T1 T2 15th PSCC, Liege, 22-26 August 2005 Session 18, Paper 5, Page 1