Modern Applied Science; Vol. 11, No. 9; 2017 ISSN 1913-1844 E-ISSN 1913-1852 Published by Canadian Center of Science and Education 39 Industrial Process Control Using LPV Musa Abdalla 1 & Tamir Shagarin 2 1 School of Engineering, The University of Jordan, Amman, Jordan 2 College of Engineering, Tafila Technical University, Tafila, Jordan Correspondence: Musa Abdalla, School of Engineering, The University of Jordan, Amman, Jordan. Tel: 962-6535-5000. E-mail: admin@mechatronix.us Received: June 8, 2017 Accepted: July 25, 2017 Online Published: August 12, 2017 doi:10.5539/mas.v11n9p39 URL: https://doi.org/10.5539/mas.v11n9p39 Abstract An industrial process control application of level and temperature is considered. The nonlinear mathematical model of the system is cast as a linear parameter varying (LPV) system. A linear matrix inequality (LMI) type of controller is successfully designed using the LMI unified approach to regulating both controlled variables, namely; temperature and level. The closed loop system is then implemented through computer simulation to show the effectiveness of the controller in performing the combined level-temperature regulation. Basically, this combined level and temperature industrial control application is used to demonstrate the effectiveness of post-modern controllers; in this case LMI based controllers. Keywords: Linear Parameter Varying System (LPV), temperature control, level control, multivariable control, LMI 1. Introduction Level and temperature control have a major importance in industrial applications especially in chemical processes which are widely used in Continuous Stirred Tank Reactors (CSTR), steam generators, distillation columns, etc. Classical control analysis simplifies the analysis for the problem into two decoupled linearized differential equations, however, under certain circumstances; this classical linear control analysis is turned out to be inadequate. Currently, the main control techniques used in level and temperature control is the conventional PID controllers based on linearized model, in which they used two separate controllers which ignore all nonlinearities and dynamic coupling between the level and temperature. Also, some researchers used the system’s nonlinear model and applied nonlinear control strategies; such as Model Predictive Control (MPC) and Slide Mode Control, etc. For a single tank model, some researchers in literature have simplified the model into two decoupled equations by taking nominal value for the volume and applied it in the energy equation (Bequette, 1998) (Seborg, 2004). While for level and temperature PID Control, others have used simple proportional controllers to control the tank level and the temperature by manipulating the flow of the liquid leaving the tank and the cooling water (Coughanowr & et. al., 2008)(Perez & Albertos, 2004). Recent studies have used PI controller in CSTR to control the level of the tank in order to keep the volume constant, and they controlled the temperature of the outflow by using two controllers; the first PI controller placed on the reactor outflow to control the level, and the second PI controller on the cooling water flow to control the reactor temperature (Perez & Albertos, 2004). For more demanding applications (Johansson, 1997), where three variables needed to be regulated, researchers have used PI controllers to control the level, pressure, and temperature of the juice in industrial deaeration process. The problem in hand is basically a simultaneous control of temperature and level in a single tank, which is depicted in figure 1. Essentially the controller needs to provide two control laws; one for controlling the inlet valve (inflow) and the second one to control the heater. It is our objective to maintain a constant temperature and level despite the unknown inflow temperature and the unknown outflow rate. Hence, the controlled variables are the level of the liquid in the tank and the temperature of the liquid inside the tank, and the manipulated variables are the inlet inflow rate and the heat rate supplied to the tank. In the literature, a simplified mathematical model is used that is composed of two linearized and decoupled differential equations, where a nominal value of the volume was taken constant in the derivation (Bequette, 1998)