Collocation Methods for Optimization in a Modelica Environment
Fredrik Magnusson, Johan Åkesson
The solution of generic dynamic optimization problems described by Modelica, and its extension Optimica, code using direct collocation methods is discussed. We start by providing a description of dynamic optimization problems in general and how to solve them by means of direct collocation. Next, an existing implementation of a collocation algorithm in JModelica.org, using CasADi and IPOPT, is presented. The extensions made to this implementation are reported.
The new implementation is compared to an old C-based collocation algorithm in JModelica.org in two benchmarks. The presented benchmarks are based on a continuously stirred tank reactor and a combined cycle power plant. The new algorithm and its surrounding framework is more flexible and shown to be several times more efficient than its predecessor.
dynamic optimization, JModelica.org, collocation, nonlinear programming, CasADi
In 9th International Modelica Conference, Munich, Germany, September 2012.