Application Of Extremum Seeking Control Research Articles

The Shading Effect on Photovoltaic Generator (GPV) Based on Reverse Osmosis (RO) Desalination System in Algeria

This paper investigates the performances analysis of PV-RO desalination system under uniform and non-uniform irradiance conditions. The main objective is the application of Extremum Seeking Control (ESC) to the GPV side in order to overcome the generated power and water quantity losses to improve the performance of the whole system. The technical design of the developed system is based on an existing RO desalination unit beside that real climatic data taken from a local mast are involved in this study. The modeling of the whole system and the control techniques adopted in this study are fully formulated. The whole system is modeled and controlled using MATLAB/Simulink. Different scenarios (healthy and shaded) based on real climatic data have been used to carry out the results. The ESC used shows its effectiveness to extract maximum power under shaded conditions for all the proposed scenarios. Compared with conventional controllers, this technique can offer extra power surrounding 685W in several cases. Furthermore, the shading conditions can affect widely freshwater production whose losses are estimated at around 82.91% for critical scenarios. The findings results are very significant for industrialists working in this field.

Real-Time Optimization of Social Distancing to Mitigate COVID-19 Pandemic Using Quantized Extremum Seeking

The application of extremum seeking control is investigated to mitigate the spread of the COVID-19 pandemic, maximizing social distancing while limiting the number of infections. The procedure does not rely on the accurate knowledge of an epidemiological model and takes realistic constraints into account, such as hospital capacities, the observation horizon of the pandemic evolution and the quantized government sanitary policy decisions. Based on the bifurcation analysis of a SEIARD compartmental model providing two possible types of equilibria, numerical simulation reveals the transient behaviour of the extremum of the constrained cost function, which, if rapidly caught by the algorithm, slowly drifts to the steady-state optimum. Specific features are easily incorporated in the real-time optimization procedure, such as quantized sanitary condition levels and long actuation (decision) periods (usually several weeks), requiring processing of the discrete control signal saturation and quantization. The performance of the proposed method is numerically assessed, considering the convergence rate and accuracy (quantization bias).

Dynamic Nonlinear Gradient Observer Based Extremum Seeking Control for Optimum Braking

The application of extremum seeking control (ESC) algorithm to antilock braking systems (ABSs) is attractive for maximizing the longitudinal braking force. Most currently reported results suffer from the drawback of steady-state oscillations around the extremum or the need to have the gradient information. In this article, a new ESC algorithm is proposed for application to ABSs to overcome these two drawbacks. The proposed algorithm is based on a novel dynamic nonlinear gradient observer (DNGO) and a longitudinal braking force estimator. The performance and the ultimate boundedness of the proposed ESC, DNGO, and the force estimator are analyzed. The proposed method is validated by simulation for dry and wet road surfaces and compared with two established results. The method is further validated on an experimental setup in the laboratory for dry and oily surfaces.

An experimental application of extremum seeking control to cultures of the microalgae Scenedesmus obliquus in a continuous photobioreactor

SummaryThe cultivation of microalgae in photobioreactors (PBRs) is important in various sectors such as food, bioenergy, pigments, and cosmetics. Productivity optimization can be achieved without the need for a dynamic process model using model‐free extremum seeking control (ESC). This article explores the use of ESC to drive the productivity of a continuous PBR to optimal or suboptimal setpoints. The latter can be achieved by estimating on‐line the gradient of a measurable performance index using a recursive least squares estimator and by regulating this gradient to a specific value (zero corresponding to the optimum) using the dilution rate as a manipulated variable. Experimental results for the cultivation of the microalgae Scenedesmus obliquus in a lab‐scale flat‐panel PBR are discussed. They show the fast convergence of ESC and its robustness towards environmental perturbations, such as changes in the incident light intensity.

On stability and application of extremum seeking control without steady-state oscillation

To enhance the dynamic and static performance of the extremum seeking control (ESC) scheme, a novel fast ESC scheme without steady-state oscillation is proposed, in which the structure of the classic ESC scheme is adjusted to make the sinusoidal excitation signal amplitude locally exponentially converge to zero. The improved ESC scheme can speed up the convergence to shorten the seeking time dramatically, and enlarge the search area to avoid falling to local extrema effectively. It can also reduce the sinusoidal excitation signal amplitude to eliminate the adverse effects of the steady-state oscillation eventually. The rigorous stability analysis and proof of the improved ESC scheme are provided in detail, and the simulation results are presented to illustrate its effectiveness and superiority. Finally, the application of the improved ESC scheme to antilock braking systems (ABS) has been discussed through comparing with classical perturbation-based ESC scheme and sliding-mode-based ESC scheme to illustrate the practicability of the improved scheme.

Application of extremum seeking control to design power oscillation damping controller

This paper presents an application of extremum seeking control to stabilize power system oscillations. This control methodology has been implemented as a supplementary control to Static Var Compensator for providing additional damping to power systems. The performance of the designed controller based on extremum seeking method has been compared with the controller based on H∞ loop-shaping technique. With time domain simulations it has been shown that the controller based on extremum seeking methodology successfully reduces power system oscillations earlier than that with the H∞ loop-shaping methodology. The effect of dither frequency and adaption gain on performance of extremum seeking controller has also been examined. The 14-Generator South East Australian equivalent power system has been used as a test system to demonstrate the ability of extremum seeking controller to reduce power system oscillations.

Maximizing Wind Turbine Energy Capture Using Multivariable Extremum Seeking Control

Maximizing energy capture has become an important issue as more turbines are installed in low wind areas. This paper investigates the application of extremum seeking control (ESC) to maximizing the energy capture of variable speed wind turbines. The optimal control torque and pitch angle are searched via ESC based on the measurement of the rotor power. The advantage of this method is the independency from accurate turbine modelling and wind measurement. Simulation was conducted on FAST for a wind turbine dynamic model, under smooth, turbulent and field recorded wind profiles. The simulation results demonstrated significant improvement in energy capture compared to the standard control with fixed reference. An anti-windup ESC was applied to overcome the integral windup due to actuator saturation which would otherwise disable the ESC process. Finally, the integrator and high-pass filter resetting schemes were applied to improve the transient under the abrupt changes of wind.