Stability and Performance Analysis of Classical Decentralized Control of Irrigation Canals (original) (raw)

REAL-TIME IMPLEMENTATION OF A DECENTRALIZED CONTROL FOR AN OPEN IRRIGATION CANAL PROTOTYPE

2007

This paper presents a real-time implementation of a decentralized LQG controller to regulate the downstream levels at the end of the pools in a four-pool open irrigation canal prototype with an upstream control concept. The objective of the controller is to keep the downstream level at a constant target value in despite of flow disturbances. Controller synthesis uses a "black box" input-output identified linear model. A previous interaction analysis, via Relative Gain Array "RGA", carried on the process model was made to verify the feasibility to design a decentralized control. The real-time close-loop results show satisfactory performance and they are compared with those obtained with a centralized LQG controller.

Decentralized Constrained Predictive Control of Irrigation Canals using On-line Linearized Models

Yearly Seminar in Automation, Industrial Electronic and Instrumentation, SAAEI´01, 2001

This paper presents the design of a predictive controller for completely decentralized control of delivery canals in irrigation systems. Delivery canals present strict physical limitations in the maximum amplitude the gates can open, and its maximum opening rate. Also, regulations give strict limitations in the maximum and minimum water level, to avoid overtopping or draining. To include these limitations in the control systems this paper proposes the implementation of a Constrained Predictive Controller, that solves online the problem of calculating an optimal control sequence in the presence of constraints, using a model of the process. This paper proposes to use for prediction a linearized model of the canal at each working point, instead of directly using the non-linear model of the system obtained from first principles. Using a linear model makes it possible to meet the strict computational limitations of a real-time implementation, without degrading the closed-loop performance. The performance of this approach in the presence of model uncertainties, constraints in the control signal, its variation and in the water level is studied

Robust controller for an open irrigation canal prototype

Indonesian Journal of Electrical Engineering and Computer Science

A Management and control of irrigation canals is a very important task whether for irrigation of agricultural land, to provide clean water, or to avoid floods. Irrigation canals are sometimes subject to intense variations due to climate change and inclement weather. For this reasons, a robust controller that allows dealing with large variation in operating conditions is proposed to control the water level of a multi-pool open irrigation canal prototype. The main objective of this study is to regulate the downstream level of each canal's pool at a constant value even with inflow disturbances. The robust controller is designed and tested in simulation for different operating conditions. The results obtained show the good behavior and the effectiveness of the designed controller.

Control-Oriented Model of a Complex Irrigation Main Canal Pool

Proceedings of the 18th IFAC World Congress, 2011

A control-oriented model of a complex irrigation main canal pool (plant), which is characterized by the exhibition of large variations in their dynamic parameters when the discharge regime changes in the operating range [Q min , Q max ], has been developed using system identification for control procedure and also using real-time data. The control-oriented model is comprised by the nominal model of the true plant and for its uncertainty region bounded by the true plant models under low and high operating discharge regimes (limit operating models). The model is obtained from the use of both experimental data, which correspond to main operating discharge regimes of the true plant, and the Prediction Error framework. The results are very encouraging since control-oriented models facilitate the design of high-performance robust controllers, which allow the operability and efficiency of irrigation main canal pools to be increased and service to the users to be improved.

Robust Control for Irrigation Canals

2013

Modern controllers are based on the use of mathematical models. However the models are always obtained through a reduction in the complexity of reality. Consequently, their ability to properly represent the general behavior of the processes is very limited. Therefore, it is advantageous to analyze the problem resulting from model uncertainty in the control of irrigation main canal pools. This problem has often been ignored in theoretical studies and in practical process control. This paper will first show a principal gains method on how to achieve the benefit of feedback in the face of uncertainties. Then it will present irrigation main canal pools example which illustrates the use of robust control to provide satisfactory performance despite of irrigation main canal pools.

Proportional and Integral Regulation of Irrigation canal Systems governed by the St Venant Equation

IFAC Proceedings Volumes, 1999

The purpose of our paper is to study control and regulation of irrigation canal systems using the St-yrenant equation. As the linearized models of these systems around equilibrium points are described by synlffictric hyperbolic partial differential equations of tvo.ro independent variables, "VC consider a class of symmetric hyperbolic systems with boundary observations. •V-le present the exact observability and exponential stability results of Rauch and Taylor in the general case. These results are made explicit by providing estimates of necessary observation length for observability and estimates of exponential decay rate for stability in function of structure parameters. Then~we apply these resultH to show that for an one-reach irrigation canal system governed by the St Venant. equation, the linearized model around an equilibrium point is exponentially stable for the open loop systenl. To guarante(~a robust regulation and a robust stability of the closed loop system wc propose proportional and integral output feedback controllers (PI-Controllers) which assure exponential stabilization of the linearized model and suppress (kno\vn or unknoVv?n) constant disturbances in the system. The work that v-re present here brings out a systematic synthesis method for designing boundary sLabillZilng PI-Controllers for irrigation systems based on linearized models of the St \Tenant equation. Copyright @ 1999IFAC Key words symmetric hyperbolic systems~exact observability, robust stabilization, exponential stability, irrigation canals j boundary PI-controllers.

Modeling and regulation of irrigation canals: existing applications and ongoing researches

SMC'98 Conference Proceedings. 1998 IEEE International Conference on Systems, Man, and Cybernetics (Cat. No.98CH36218), 1998

The objective of this survey paper is to review the main methodologies used in the development of models and in the design of controllers for irrigation canal systems. These systems are characterized by time delays, non-linear features, strong unknown perturbations, and interactions among subsystems. Although a large part of these developments are still at the research stage, more and more of these techniques have successful field implementations. MODELlNG An irrigation canal is an open water hydraulic system, whose objective is mainly to convey water from its source (Dam, River) down to its final users (Farmers). Cross structures (mainly hydraulic gates) are operated in order to control the water levels, discharges and/or volumes along this canal (Fig. I).

First Experimental Results of Nonlinear Control in Irrigation Canals

IFAC Proceedings Volumes, 2004

This paper presents various real-time results obtained on an experimental canal reach. with two types of nonlinear controllers. The controllers have been designed on the basis of a simple collocation model previously proposed for water dynamics in canal reaches. They only use water level measurements and are based on a non linear observer for water flow rate estimation. Stability conditions for the corresponding closed-loop schemes result from previous studies. and successful experimental results show that such conditions can indeed be achieved in practice.

Modeling, control and field tests on an experimental irrigation canal

2002

Irrigation canals are complex hydraulic systems difficult to control. Many models and control strategies have already been developed using linear control theory. In the present study, a PI controller is developed and implemented in a brand new prototype canal and its features evaluated experimentally. The base model relies on the linearized Saint-Venant equations which is compared with a reservoir model to check its accuracy. This technique will prove its capability and versatility in tuning properly a controller for this kind of systems

Distributed model predictive control of irrigation canals

Networks & Heterogeneous Media, 2009

Irrigation canals are large-scale systems, consisting of many interacting components, and spanning vast geographical areas. For safe and efficient operation of these canals, maintaining the levels of the water flows close to prespecified reference values is crucial, both under normal operating conditions as well as in extreme situations. Irrigation canals are equipped with local controllers, to control the flow of water by adjusting the settings of control structures such as gates and pumps. Traditionally, the local controllers operate in a decentralized way in the sense that they use local information only, that they are not explicitly aware of the presence of other controllers or subsystems, and that no communication among them takes place. Hence, an obvious drawback of such a decentralized control scheme is that adequate performance at a system-wide level may be jeopardized, due to the unexpected and unanticipated interactions among the subsystems and the actions of the local controllers. In this paper we survey the state-of-the-art literature on distributed control of water systems in general, and irrigation canals in particular. We focus on the model predictive control (MPC) strategy, which is a model-based control strategy in which prediction models are used in an optimization to determine optimal control inputs over a given horizon. We discuss how communication among local MPC controllers can be included to improve the performance of the overall system. We present a distributed control scheme in which each controller employs MPC to determine those actions that maintain water levels after disturbances close to pre-specified reference values. Using the presented scheme the local controllers cooperatively strive for obtaining the best systemwide performance. A simulation study on an irrigation canal with seven reaches illustrates the potential of the approach.