scholarly journals Model-Free Extremum Seeking Control of Bioprocesses: A Review with a Worked Example

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1209
Author(s):  
Laurent Dewasme ◽  
Alain Vande Wouwer
Keyword(s):  
Dynamic Models ◽  
Operating Conditions ◽  
Extremum Seeking ◽  
Usual Practice ◽  
Extremum Seeking Control ◽  
Model Free ◽  
Worked Example ◽  
Current Trends ◽  
Simple Simulation ◽  
Recent Developments

Uncertainty is a common feature of biological systems, and model-free extremum-seeking control has proved a relevant approach to avoid the typical problems related to model-based optimization, e.g., time- and resource-consuming derivation and identification of dynamic models, and lack of robustness of optimal control. In this article, a review of the past and current trends in model-free extremum seeking is proposed with an emphasis on finding optimal operating conditions of bioprocesses. This review is illustrated with a simple simulation case study which allows a comparative evaluation of a few selected methods. Finally, some experimental case studies are discussed. As usual, practice lags behind theory, but recent developments confirm the applicability of the approach at the laboratory scale and are encouraging a transfer to industrial scale.

scholarly journals Extremum Seeking Control for Model-Free Auto-Tuning of Powered Prosthetic Legs

2020 ◽  
Vol 28 (6) ◽  
pp. 2120-2135 ◽  
Author(s):  
Saurav Kumar ◽  
Alireza Mohammadi ◽  
David Quintero ◽  
Siavash Rezazadeh ◽  
Nicholas Gans ◽  
...  
Keyword(s):  
Extremum Seeking ◽  
Extremum Seeking Control ◽  
Model Free ◽  
Auto Tuning

Using Extremum Seeking Control to Improve the Power Capture of Midsize Hydrostatic Wind Turbines

2021 ◽  
Author(s):  
Daniel Escobar-Naranjo ◽  
Biswaranjan Mohanty ◽  
Kim A. Stelson
Keyword(s):  
Adaptive Control ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Control Strategies ◽  
Torque Control ◽  
Extremum Seeking ◽  
Extremum Seeking Control ◽  
Model Free ◽  
Point Tracking ◽  
Power Capture

Abstract Adaptive control strategies are commonly used for systems that change over time, such as wind turbines. Extremum Seeking Control (ESC) is a model-free real-time adaptive control strategy commonly used in conventional gearbox wind turbines for Maximum Power Point Tracking (MPPT). ESC optimizes the rotor power by constantly tuning the torque control gain (k) when operating below rated power. The same concept can be applied for hydrostatic wind turbines. This paper studies the use of ESC for a 60-kW hydrostatic wind turbine. First, a systematic approach to establish the ideal ESC is shown. Second, a comparison of the power capture performance of ESC versus the conventional torque control law (the kω2 law) is shown. The simulations include a timesharing power capture coefficient (Cp) to clearly show the advantages of using ESC. Studies under steady and realistic wind conditions show the main advantages of using ESC for a hydrostatic wind turbine.

A Multi-Variable Newton-Based Extremum Seeking Control for a Chilled Water Plant With Variable Water and Air Flow

2014 ◽  
Author(s):  
Baojie Mu ◽  
Yaoyu Li ◽  
Bin Hu ◽  
John E. Seem
Keyword(s):  
Energy Saving ◽  
Power Efficiency ◽  
Cooling Tower ◽  
Water Flow Rate ◽  
Extremum Seeking ◽  
Total Power ◽  
Extremum Seeking Control ◽  
Model Free ◽  
Water Plant ◽  
Chilled Water

The chilled water system, typically consisting of chiller and cooling tower, plays a major role in the ventilation and air-conditioning systems in commercial buildings. Due to the significant power consumption of such system, improvement of its efficiency would lead to significant benefit in energy saving. As the system characteristics and operational conditions can vary dramatically in practice, model-free self-optimizing control is of high interest in practice. In this study, the chilled-water plant being studied consists of one screw chiller and one counter-flow cooling tower. A multi-variable Newton-based extremum seeking control (ESC) scheme is applied to maximize the power efficiency in real time with the cooling load being satisfied. The feedback for the ESC controller is the total power of the chiller compressor, the cooling tower fan and the condenser water pump, while the inputs are cooling-tower fan speed and the condenser-loop water flow rate. The two-input Newton-based ESC controller is simulated with a Modelica based dynamic simulation model of the chiller-tower system. Two inner-loop PI controllers are used to regulate the temperatures of evaporator superheat and evaporator leaving water at their respective setpoints. Simulation results validate the effectiveness of the proposed control strategy. Remarkable energy saving is observed for several testing conditions.

Optimal Subcooling in Vapor Compression Systems via Extremum Seeking Control

2013 ◽  
Author(s):  
Justin P. Koeln ◽  
Andrew G. Alleyne
Keyword(s):  
System Architecture ◽  
Operating Conditions ◽  
Extremum Seeking ◽  
Vapor Compression ◽  
System Efficiency ◽  
Limited Information ◽  
Extremum Seeking Control ◽  
Additional Degree ◽  
Alternative System ◽  
Vapor Compression Systems

Building systems constitute a significant portion of the overall energy consumed each year in the U.S., and a large portion of this energy is used by air-conditioning systems. Therefore, the efficiency of these systems is important. This paper presents a method to increase system efficiency using an alternative system architecture for vapor compression systems. This architecture creates an additional degree of freedom which allows for independent control of condenser subcooling. It is found that there exists a non-zero subcooling that maximizes system efficiency; however, this optimal subcooling can change with different operating conditions. Thus, extremum seeking control is applied to find and track the optimal subcooling using only limited information of the system. In a simulation case study, a 10% reduction in energy consumption is reported when using the alternative system architecture and extremum seeking control when compared to a conventional system configuration.

Power-setpoint extremum seeking control for maximizing wind power capture of turbine and farm operation

2020 ◽  
pp. 0309524X2097991
Author(s):  
Devesh Kumar ◽  
Yaoyu Li ◽  
Zhongyou Wu
Keyword(s):  
Control Strategy ◽  
Extremum Seeking ◽  
Power Demand ◽  
Extremum Seeking Control ◽  
Energy Capture ◽  
Model Free ◽  
Free Region ◽  
Power Capture ◽  
Back Calculation ◽  
Nested Loop

In this paper, we propose a power-setpoint based Extremum Seeking Control (ESC) framework for model-free Region-2 controls for maximizing the power capture for turbine and farm operation, without dependency on wind measurement. As a major obstacle for retrofitting wind turbine/farm controls is that only the power setpoint is accessible, the power-setpoint based ESC framework is proposed with a back-calculation anti-windup structure. If increasing the power demand cannot further increase actual power output, the anti-windup structure automatically holds the power demand setpoint. For farm operation, the proposed method is integrated into the Delay-compensated Nested-loop ESC. The proposed method is evaluated by simulations on the SimWindFarm platform for both single-turbine and farm operation scenarios. The results demonstrate the capability of tracking the achievable optimum power for turbine and farm operation, with only reasonable increase of some loads. The proposed method promises an easy-to-implement model-free retrofitting control strategy for enhancing wind energy capture.

scholarly journals Russia’s Foreign Policy Evolution in the New Balkan Landscape

2020 ◽  
Vol 56 (3-4) ◽  
pp. 179-199
Author(s):  
Ekaterina Entina ◽  
Alexander Pivovarenko
Keyword(s):  
Foreign Policy ◽  
Soviet Union ◽  
Regional Security ◽  
Southeast Europe ◽  
The Balkans ◽  
Current Trends ◽  
The Soviet Union ◽  
Recent Developments ◽  
The Difference

The article reflects on the issue of the foreign policy strategy of modern Russia in the Balkans region. One of the most significant aspects of this problem is the difference in views between Russia and the West. Authors show how different interpretations of the events in former Yugoslavia in the 1990s and the beginning of the 2000s predetermined the sense of mutual suspicion and mistrust which spread to other regions such as the post-Soviet space. Exploring differences between the Russian and the Western (Euro-Atlantic) views on the current matters, authors draw attention to fundamental differences in terminology: while the Western narrative promotes more narrow geographical and political definitions (such as the Western Balkan Six), traditional Russian experts are more inclined to wider or integral definitions such as “the Balkans” and “Central and Southeast Europe”. Meanwhile none of these terms are applicable for analysis of the current trends such as the growing transit role of the Balkans region and its embedding in the European regional security architecture. Therefore, a new definition is needed to overcome the differences in vision and better understand significant recent developments in the region. Conceptualizing major foreign policy events in Central and Southeast Europe during the last three decades (the 1990s, 2000s and 2010s), authors demonstrate the significance of differences in tools and methods between the Soviet Union and the modern Russia. Permanent need for adaptation to changing political and security context led to inconsistence in Russian Balkan policy in the 1990s. Nevertheless, Russia was able to preserve an integral vision of the region and even to elaborate new transregional constructive projects, which in right political circumstances may promote stability and become beneficial for both Russia and the Euro-Atlantic community.

Adaptive Extremum Seeking Control based LCL Filter Resonant Frequency Online Estimation

2021 ◽  
pp. 1-1
Author(s):  
Yuheng Wu ◽  
Mohammad Hazzaz Mahmud ◽  
Radha Sree Krishna Moorthy ◽  
Madhu Chinthavali ◽  
Yue Zhao
Keyword(s):  
Resonant Frequency ◽  
Extremum Seeking ◽  
Lcl Filter ◽  
Extremum Seeking Control ◽  
Online Estimation
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