Simulation of a Photovoltaic Conversion System using Energetic Macroscopic Representation

Archive ouverte : Communication dans un congrès

Lhomme, Walter | Delarue, Philippe | Giraud, Frédéric | Lemaire-Semail, Betty | Bouscayrol, Alain

Edité par HAL CCSD

International audience. — The Energetic Macroscopic Representation (EMR) has been developed in 2000 to develop control of electric systems. Since 2002 this graphical tool has been introduced to teach control of electrical systems in France, then Canada and Switzerland. A Photovoltaic Conversion System is simulated using EMR in order to present an actual and valuable example for students within renewable energy applications.. Introduction Nowadays, control of electrical systems is of main interest in electrical engineers teaching [1]-[3]. But it requires skills in various scientific fields such as power electronics, electrical machines, automatic control, mechanics and control electronics. Several graphical description has been introduced in order to represent in a uniform way multi-physical systems, such as Bond-Graph (BG) [4], Power Oriented Graph (POG), Causal Ordering Graph (COG) [6][7], or Energetic Macroscopic Representation (EMR) [8]. BG and POG are structural descriptions more dedicated to the system design. COG and EMR are functional descriptions more focused on the control design, because of the use of the exclusive integral causality [9][10]. In that case, the control scheme of the system can be directly deduced from an inversion of the model description [11]. These two descriptions have been successfully used for control of various applications [11]-[13]. Because of the system-oriented description for modelling and control, EMR is a valuable methodology to teach control of electrical systems. This formalism is now taught in some French universities [14][15], at University of Québec Trois Rivières (Canada), at Ecole Polytechnique Fédérale de Lausanne (Switzerland), and some recent experiences have been realized at Tsinghua University (China), Aalto University (Finland) and Polytechnical University of Catalunya (Barcelona, Spain) [16]. Indeed such a graphical description enables a unified way for causal description of the components of electromechanical. Moreover, summer schools are regularly organized worldwide (Lille, France, [16]. But, because EMR is a new systemic approach, realistic and simple examples have to illustrate the different concepts. Moreover, practice is required in the manipulation of the different pictograms, their connections and the deduced control, in particular during summer schools when the students have only 3 days of lectures on this topic. Simulation of simple systems have thus been developed in order to illustrated the modelling and the control methods using EMR in very short simulation sessions (typically two sessions of four hours each). First the simulation of an electric vehicle using a DC machine has been developed using EMR library and Matlab-Simulink© [14]. But other systems have to be simulated to demonstrate the flexibility of the method. In this paper, the simulation of a Photovoltaic (PV) system is studied in order to supply a hydraulic pump. Energy is extracted from the system using a MMPT strategy and is stored in a battery tank. The pump is moved by a DC machine. The EMR of the system is described, and the control scheme is derived from the inversion of this EMR. Finally the entire system is simulated in Matlab Simulink using an EMR library.

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