Short-term electricity planning with increase wind capacity Sérgio Pereira a , Paula Ferreira a, * ,1 , A.I.F. Vaz b, 2 a Center for Industrial and Technology Management, University of Minho, Campus Azurém, 4800-058 Guimarães, Portugal b Department of Production and Systems, University of Minho, Campus de Gualtar, 4710-057, Portugal article info Article history: Received 3 August 2013 Received in revised form 7 January 2014 Accepted 9 January 2014 Available online xxx Keywords: Wind power Electricity planning Renewable energy sources Thermal power Hydropower abstract The variable electricity output of the RES (renewable energy sources) power plants, such as wind and hydropower, is an important challenge for the electricity system managers. This paper addresses the problem of an electricity system supported mainly on hydro, thermal, and wind power plants. A binary mixed integer non-linear optimization model with hourly time step is described. The model is applied to a system close to the Portuguese electricity case assuming demand forecasts for the year 2020. The main objective of this paper was to analyze the impact that different levels of installed wind power can have in the operation of this electricity system, taking into account the hourly and intra-annual variation of the renewable resources, the demand projections and also the technical restriction of thermal power plants. The results confirmed wind power as strategic technology to reduce both the marginal cost and CO 2 emissions. According to the simulations run, wind power will not replace hydropower but a decrease of thermal power production is foreseen as more wind power is added to the system. Large wind power scenarios will particularly affect gas power plants performance, reducing both the load level and the number of operating hours. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Over the passed decades, electricity system generation has gone over a set of different changes. Different technologies start to arise and the importance of RES (Renewable Energy Sources) for elec- tricity generation is now remarkable. RES technologies are usually characterized by zero CO 2 gas emissions, lower operation and maintenance costs but higher investment costs. The promotion and use of RES for electricity generation is one of the most important greenhouse gas mitigation measures [1]. However, the increasing use of these technologies creates new challenges to the electricity power management. They are frequently characterized by production of variable output, not subject to dispatch, and can benefit from feed-in-tariffs. Never- theless, in most electricity systems, large thermal and hydropower plants compete in the market for dispatch. The intra-annual seasonality and the variability of wind power output can be particularly challenging, significantly impacting the performance of thermal power plants operating in the same elec- tricity system. According to Ref. [2]; large-scale wind power development affects short term operation of the electricity system, as well as the optimal generation technology mix since wind in- crease significantly the variability of energy generation. The vari- ability of wind power into the grid will enforce thermal generators ramping to compensate supplying disruptions or to operate at low load conditions. According to Ref. [3]; increasing variability and unpredictability in the power system, due to wind curve charac- teristics, will frequently originate the increasing number of start- ups, ramping, and periods of operation at low load levels. In line with this, [4] supports that, with the increase of wind power gen- eration all over the world, the integration of wind power genera- tion in electricity power systems needs to be carefully performed and requires new concepts in operation, control, and management. In their study, a joint operation between a wind farm and a hydro- pump plant is addressed having into account the uncertainty of the wind power forecast. Other concern that is usually related to RES technologies such as wind and hydro is the difficulty on forecasting their availability. Different studies have focused on this thematic. Ref. [5] studies the impact of wind power forecasting on the unit commitment prob- lem and economical dispatch. A set of different scenarios to deal with wind uncertainty were considered, transforming the problem into a stochastic one. Despite the complexity usually associated to the stochastic problems that usually leads to better results, the authors concluded that a deterministic method combined with an increased reserve requirement can produce results that are * Corresponding author. E-mail addresses: sergiop@dps.uminho.pt (S. Pereira), paulaf@dps.uminho.pt (P. Ferreira), aivaz@dps.uminho.pt (A.I.F. Vaz). 1 Support for this author was also provided by CGIT research center. 2 Support for this author was also provided by Algoritmi Research Center. Contents lists available at ScienceDirect Energy journal homepage: www.elsevier.com/locate/energy 0360-5442/$ e see front matter Ó 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.energy.2014.01.037 Energy xxx (2014) 1e11 Please cite this article in press as: Pereira S, et al., Short-term electricity planning with increase wind capacity, Energy (2014), http://dx.doi.org/ 10.1016/j.energy.2014.01.037