Optimering av ett småskaligtvattenkraftsystem
This master thesis covers the seasonal planning of a small scale hydropower system. The system in this study is owned and operated by Mälarenergi Vattenkraft AB. The total system consists of 4 different main rivers with 24 hydropower stations and several dams. The total installed power in the system is 43.75 MW. Most of the hydropower stations are regarded as small scale hydropower stations and thus entitled to green certificates.In this report the issue of planning is formulated as an optimization problem. The objective is to maximize the revenue during a given period, while considering hydrological couplings, physical and legal limitations. To provide some orientation and background to the problem the first chapters in the report cover hydropower, system planning, the electrical market and optimization. An essential part of the work consists of modeling of hydropower systems and two different models are accomplished. Both models include delay time and maximum discharge changes among other things. The first model is a mixed integer linear model (MILP) where the power production is expressed in integers and continuous variables. Minimal discharge, prohibited intervals and non decreasing marginal production equivalent are also included. The second model is a nonlinear model (NLP) that in contrast to the first model includes simplified head dependence. On the other hand some other property must be left out.To solve the optimization problem mathematical programming in GAMS is used. In GAMS the described models and the basic numerical data for the system can be formulated and optimized. A number of test cases with different conditions are made to study how the system could be run optimally and what factors that can be identified as important. The results of the simulations are extensive and an interesting selection of these are analyzed and presented in the report.