A Multi-rate Moving Horizon Estimation Framework for Electric Arc Furnace Operation**This work is supported by the McMaster Steel Research Center (SRC) and the McMaster Advanced Control Consortium (MACC).

Electric arc furnaces (EAFs) are widely used in steel industries to produce molten steel from scrap metal. EAF operation, being a highly energy intensive process, is characterized by a limited number of measurements at multiple rates, most of which do not correspond to system states. The ability to estimate the states would enhance the application of control and real-time optimization strategies. In this work, a multi-rate moving horizon estimation (MHE) framework for EAF operation under flat-bath conditions is introduced and implemented. Key features are the restructuring of the MHE problem to a parameter estimation problem, multi-rate measurement handling, and use of a nonlinear model. The approach is implemented in the gPROMS (General Process Modeling System) modeling language. The components of the framework are presented, and the method is applied to a case study illustrating its performance.