Implementation of a Differential Flatness Based Controller on an Open Channel Using a SCADA System

International audienceWith a population of more than 6 billion people, food production from agriculture must be raised to meet increasing demand. While irrigated agriculture provides 40% of the total food production, it represents 80% of the freshwater consumption worldwide. In summer and drought conditions, efficient management of scarce water resources becomes crucial. The majority of irrigation canals are managed manually, however, with large water losses leading to low water efficiency. This article focuses on the development of algorithms that could contribute to more efficient management of irrigation canals that convey water from a source, generally a dam or reservoir located upstream, to water users. We also describe the implementation of an algorithm for real-time irrigation operation using a supervision, control, and data acquisition (SCADA) system with an automatic centralized controller. Irrigation canals can be viewed and modeled as delay systems since it takes time for the water released at the upstream end to reach the user located downstream. We thus present an open-loop controller that can deliver water at a given location at a specified time. The development of this controller requires a method for inverting the equations that describe the dynamics of the canal in order to parameterize the controlled input as a function of the desired output. The Saint-Venant equations [1] are widely used to describe water discharge in a canal. Since these equations are not easy to invert, we consider a simplified model, called the Hayami model. We then use differential flatness to invert the dynamics of the system and to design an open-loop controller

A survey of differential flatness-based control applied to renewable energy sources

Conference ProceedingsThis paper presents an overview of various methods used to minimize the fluctuating impacts of power generated from renewable energy sources. Several sources are considered in the study (biomass, wind, solar, hydro and geothermal). Different control methods applied to their control are cited, alongside some previous applications. Hence, it further elaborates on the adoptive control principles, of which includes; Load ballast control, dummy load control, proportional integral and derivative (PID) control, proportional integral (PI) control, pulse-width modulation (PWM) control, buck converter control, boost converter control, pitch angle control, valve control, the rate of river flow at turbine, bidirectional diffuser-augmented control and differential flatnessbased controller. These control operations in renewable energy power generation are mainly based on a steady-state linear control approach. However, the flatness based control principle has the ability to resolve the complex control problem of renewable energy systems while exploiting their linear properties. Using their flatness properties, feedback control is easily achieved which allows for optimal/steady output of the system components. This review paper highlights the benefits that range from better control techniques for renewable energy systems to established robust grid (or standalone generations) connections that can bring immense benefits to their operation and maintenance costs

Flatness-based control of open-channel flow in an irrigation canal using SCADA

Open channels are used to distribute water to large irrigated areas. In these systems, ensuring timely water delivery is essential to reduce operational water losses. This article derives a method for open-loop control of open channel flow, based on the Hayami model, a parabolic partial differential equation resulting from a simplification of the Saint-Venant equations. The open-loop control is represented as infinite series using differential flatness. Experimental results show the effectiveness of the approach by applying the open-loop controller to a real irrigation canal located in South of France

FLATNESS BASED CONTROL OF MICRO-HYDROKINETIC RIVER ELECTRIFICATION SYSTEM

Published ThesisIn areas where adequate water resource is available, hydrokinetic energy conversion systems are currently gaining recognition, as opposed to other renewable energy sources such as solar or wind energy. The operational principle of hydrokinetic energy is not similar to traditional hydropower generation that explores use of the potential energy of falling water, which has drawbacks such as the expensive construction of dams and the disturbance of aquatic ecosystems. Hence, hydrokinetic energy generates electricity by making use of underwater turbines to extract the kinetic energy of flowing water, with no construction of dams or diversions. A hydrokinetic turbine uses flowing water, which varies with climatic conditions throughout the year, to power the shaft of a generator, hence, generating an unstable energy output. The aim of this dissertation is to develop a controller that will be used to stabilize the output voltage and frequency generated in a hydrokinetic energy system. An overview of various methods used to minimize the fluctuating impacts of power generated from renewable energy sources is included in the current conducted research. Several renewable energy sources such as biomass, wind, solar, hydro and geothermal have been discussed in the literature review. Different control methods and topologies have been cited. Hence, the study elaborates on the adoptive control principles, which include the load ballast control, dummy load control, proportional integral and derivative (PID) controller system, proportional integral (PI) controller system, pulse-width modulation (PWM) control, pitch angle control, valve control, the rate of river flow at the turbine, bidirectional diffuser-augmented control and differential flatness based controller. These control operations in renewable energy power generation are mainly based on a linear control approach. In the case whereby a PI power controller system has been developed for a variable speed hydrokinetic turbine system, a DC-DC boost converter is used to keep constant DC link voltage. The input DC current is regulated to follow the optimized current reference for maximum power point operation of the turbine system. The DC link voltage is controlled to feed the current in the grid through the line side PWM inverter. The active power is regulated by q-axis current while the reactive power is regulated by d-axis current. The phase angle of utility voltage is detected using PLL (phased locked loop) in a d-q synchronous reference frame. The proposed scheme is modelled and simulated using MATLAB/ Simulink, and the results give a high quality power conversion solution for a variable speed hydrokinetic system. In the second case, whereby the differential flatness concept is applied to a controller, the idea of this concept is to generate an imaginary trajectory that will take the system from an initial condition to a desired output generating power. This control concept has the ability to resolve complex control problems such as output voltage and frequency fluctuations of renewable energy systems, while exploiting their linear properties. The results show that the generated outputs are dynamically adjusted during the voltage regulation process. The advantage of the proposed differential flatness based controller over the traditional PI control resides in the fact that decoupling is not necessary and the system is much more robust as demonstrated by the modelling and simulation studies under different operating conditions, such as changes in water flow rate

Modeling and Simulation of Robots Playing Football using MA TLAB/SIMULINK

Cooperating autonomous robots are characterized as intelligent systems that combine perception, reasoning, and action to perform cooperative tasks under circumstances that are insufficiently known in advance, and changing during task execution. There are various reasons to why we should build cooperative robots. They include increasing reliability and robustness through redundancy, decreasing task completion time through parallelism and decreasing cost through simpler individual robot design. Cooperative robots can be applied in various fields such as mining, construction, planetary exploration, automated manufacturing, search and rescue missions, cleanup of hazardous waste, industrial/household maintenance, nuclear power plant decommissioning, security, and surveillance. However, in this project cooperating autonomous robots are applied in terms of robots playing football. A fully autonomous robot has the ability to gain information about the environment, work for an extended period without human intervention, move either all or parts of itself throughout its operating environment without human assistance and to avoid situations that are harmful to people, property or itself. An autonomous robot may also learn or gain new capabilities like adjusting strategies for accomplishing its task(s) or adapting to changing surrounding. Therefore this project will inculcate the criteria of autonomous robots in term of robots playing football. This study will incorporate programming using MATLAB/SIMULINK, producing mathematical models and applying control analysis methods

Kinetic Intersections as a Source of Information on Rate Coefficients

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Flatness-based Deformation Control of an Euler-Bernoulli Beam with In-domain Actuation

This paper addresses the problem of deformation control of an Euler-Bernoulli beam with in-domain actuation. The proposed control scheme consists in first relating the system model described by an inhomogeneous partial differential equation to a target system under a standard boundary control form. Then, a combination of closed-loop feedback control and flatness-based motion planning is used for stabilizing the closed-loop system around reference trajectories. The validity of the proposed method is assessed through well-posedness and stability analysis of the considered systems. The performance of the developed control scheme is demonstrated through numerical simulations of a representative micro-beam.Comment: Preprint of an original research wor

Interfacial dynamics in processing of materials with normal stress differences

Processing of elastic non-Newtonian fluids is of critical importance to many industrial manufacturing processes. Three different processes are analyzed in this work: co-extrusion of polymer melts, inclined plane flow of soft particle pastes, and roll-to-roll processing of soft particle pastes. These three processes are examined using stability theory and finite element simulation as tools and, when possible, experimental results obtained by collaborators are used to verify and test findings. The polymer co-extrusion process analyzed in this work is an experimental device at Case Western Reserve University (CWRU) that creates many layered polymer films with individual layer thicknesses on the order of microns to 100s of nanometers. Due to forces acting between the layers during the co-extrusion process, the layered structure can be damaged or destroyed. Two key components of this process are analyzed using the finite element method: the feedblock for the co-extruder and the layer multiplier dies. The study of the feedblock identifies two critical improvements for the process that help mitigate the destruction of the layered structure. The finite element analysis of the multiplier dies identify a way to reduce the high pressure drop through the multiplier die, and a design that helps preserve the layered structure. These results are confirmed experimentally by collaborators at CWRU. In the second part of this work, flow of a soft particle paste down an inclined plane is analyzed using a linear stability theory. This problem is tackled a preliminary study to the roll-to-roll processing of the same material. Stability of inclined plane flow has been studied in the literature for a variety of different materials. The destabilizing second normal stress differences exhibited by the soft particle paste are found to compete with the stabilizing force of surface tension. Stable and unstable wavenumber ranges are determined for this problem, as well as the fastest growing mode. This is then used to compute the expected wave lengths seen for varying yield stress. Lastly, the stability of flow of a soft particle paste in a forward roll coating process is analyzed. Forward roll coating of soft particle pastes is a common industrial process, particularly in the area of paint application. The analysis examines the impact of material properties on the so –called ribbing instability that is known to occur in many roll-to-roll processes. A method for analyzing the stability of Newtonian fluids in forward roll coating is expanded to power law fluids. The results show that stability strongly depends on the capillary number and the power law index.Chemical Engineerin