Improvement of Biogas Production in Anaerobic Digestion Process

Abstract

The production of biogas enables environmental preservation and sustainable development of rural areas and landlocked regions, as well as diversification of renewable energy resources. This paper is a contribution to improving the production of biogas by Sliding Mode Control (SMC). In the literature there are many models describing the behaviour of reactions during anaerobic digestion and used for control design. The AM2 model is one of the simplest models and can be exploited easily for the control design purposes. In this paper, the reduced model AM2 was exploited to develop and testing by simulations the robust control law SMC. The results obtained have proved the effectiveness of the control method proposed in this paper. A study of the robustness for monitoring and disturbances rejection demonstrated the great interest of this method, which is a non-linear technique and gives very good results in terms of robustness but it presents the problem of chattering. In practice, the chattering of the control action can cause premature wear of the actuators or parts of the system due to heavy oscillations. The chattering phenomenon is caused by the discontinuous term which appears in the control signal. This paper presents a solution to the chattering problem by replacing the discontinuous term with a continuous one. Different Simulations and comparisons are presented and interpreted with satisfactory results.