Coordinated Operation of Centrifugal Compressors in Series via Model Predictive Control

2016 ◽  
Author(s):  
Mehmet Mercangöz ◽  
Andrea Stefani ◽  
Andrea Cortinovis
Keyword(s):  
High Performance ◽  
Transfer Functions ◽  
Control Strategies ◽  
Step Response ◽  
Response Analysis ◽  
Centrifugal Compressors ◽  
Control Loops ◽  
Plant Behavior ◽  
In Series ◽  
Surge Control

This paper investigates the control challenges in the operation of centrifugal compressors in series configuration, which arise from the interactions of the different control loops for process and anti-surge control. The investigation is carried out with simulations, where two compressors in series are considered to represent the simplest possible case for systems analysis. The simulations are based on a well-known nonlinear compressor model to represent the plant behavior as close to reality as possible. The paper starts with the derivation of linear transfer functions from step response analysis, which are used to develop both advanced decentralized control solutions using loop decoupling schemes as well as a model predictive controller (MPC). The various alternative control strategies are then investigated by introducing a typical downstream disturbance case that pushes the compressors towards surge conditions while creating interactions among all control loops. The simulation results are analyzed to determine the advantages and the shortcomings of the different control strategies. The MPC based approach stands out as a high performance alternative to traditional control schemes relying on simple feedback and feedforward elements.

scholarly journals Comparative Study and Overview of Field-Oriented Control Techniques for Six-Phase PMSMs

2021 ◽  
Vol 11 (17) ◽  
pp. 7841
Author(s):  
Marek Furmanik ◽  
Lukáš Gorel ◽  
Daniel Konvičný ◽  
Pavol Rafajdus
Keyword(s):  
Motor Control ◽  
Control Strategies ◽  
Current Trend ◽  
Detailed Comparison ◽  
Step Response ◽  
Response Analysis ◽  
Field Oriented Control ◽  
Permanent Magnet Synchronous Machines ◽  
Control Applications ◽  
Control Techniques

This paper targets the main current trend in automotive motor control applications, i.e., six-phase permanent−magnet synchronous machines. Multiphase machines have been studied for more than one decade, but they are currently becoming more and more important for automotive technology. Increased safety and improved reliability are the two main reasons why six-phase machines conquer safety-critical motor control applications. The paper provides a detailed description, analysis, and comparison of two field-oriented control strategies for six-phase machines. The article consists of four main parts: (1) a general introduction of the application field of six-phase machines; (2) a description of two different field-oriented control techniques; (3) a presentation of the experimental results, e.g., frequency and step response analysis, as well as a comparison between a mathematical model and a real system; (4) a detailed comparison of strategies including pros and cons, with a strong focus on the main advantages.

scholarly journals Transient Analysis and Execution-Level Power Tracking Control of the Concentrating Solar Thermal Power Plant

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1564
Author(s):  
Xiufan Liang ◽  
Yiguo Li
Keyword(s):  
Power Output ◽  
Tracking Control ◽  
Power Plants ◽  
Transfer Functions ◽  
Control Strategies ◽  
Thermal Power ◽  
Reference Signal ◽  
Transient Behavior ◽  
Step Response ◽  
Integral Control

Concentrating solar power (CSP) is a promising technology for exploiting solar energy. A major advantage of CSP plants lies in their capability of integrating with thermal energy storage; hence, they can have a similar operability to that of fossil-fired power plants, i.e., their power output can be adjusted as required. For this reason, the power output of such CSP plants is generally scheduled to maximize the operating revenue by participating in electric markets, which can result in frequent changes in the power reference signal and introduces challenges to real-time power tracking. To address this issue, this paper systematically studies the execution-level power tracking control strategy of an CSP plant, primarily aiming at coordinating the control of the sluggish steam generator (including the economizer, the boiler, and the superheater) and the fast steam turbine. The governing equations of the key energy conversion processes in the CSP plant are first presented and used as the simulation platform. Then, the transient behavior of the CSP plant is analyzed to gain an insight into the system dynamic characteristics and control difficulties. Then, based on the step-response data, the transfer functions of the CSP plant are identified, which form the prediction model of the model predictive controller. Finally, two control strategies are studied through simulation experiments: (1) the heuristic PI control with two operation modes, which can be conveniently implemented but cannot coordinate the control of the power tracking speed and the main steam parameters, and (2) advanced model predictive control (MPC), which overcomes the shortcoming of PI (Proportional-Integral) control and can significantly improve the control performance.

scholarly journals A Dual Frequency Ultrasonic Cleaning Tank Developed by Transient Dynamic Analysis

2021 ◽  
Vol 11 (2) ◽  
pp. 699
Author(s):  
Worapol Tangsopa ◽  
Jatuporn Thongsri
Keyword(s):  
High Performance ◽  
Acoustic Pressure ◽  
Single Frequency ◽  
Response Analysis ◽  
Dual Frequency ◽  
Transient Dynamic Analysis ◽  
Ultrasonic Cleaning ◽  
Calculational Method ◽  
Successful Design ◽  
Harmonic Response Analysis

At present, development of manufacturer’s ultrasonic cleaning tank (UCT) to match the requirements from consumers usually relies on computer simulation based on harmonic response analysis (HRA). However, this technique can only be used with single-frequency UCT. For dual frequency, the manufacturer used information from empirical experiment alongside trial-and-error methods to develop prototypes, resulting in the UCT that may not be fully efficient. Thus, lack of such a proper calculational method to develop the dual frequency UCT was a problem that greatly impacted the manufacturers and consumers. To resolve this problem, we proposed a new model of simulation using transient dynamics analysis (TDA) which was successfully applied to develop the prototype of dual frequency UCT, 400 W, 18 L in capacity, eight horn transducers, 28 and 40 kHz frequencies for manufacturing. The TDA can indicate the acoustic pressure at all positions inside the UCT in transient states from the start to the states ready for proper cleaning. The calculation also reveals the correlation between the positions of acoustic pressure and the placement positions of transducers and frequencies. In comparison with the HRA at 28 kHz UCT, this TDA yielded the results more accurately than the HRA simulation, comparing to the experiments. Furthermore, the TDA can also be applied to the multifrequency UCTs as well. In this article, the step-by-step development of methodology was reported. Finally, this simulation can lead to the successful design of the high-performance dual frequencies UCT for the manufacturers.

Continuous Finite-Time Torque Control for Flexible Assistance Exoskeleton with Delay Variation Input

Robotica ◽  
2020 ◽  
pp. 1-26
Author(s):  
Tao Xue ◽  
ZiWei Wang ◽  
Tao Zhang ◽  
Ou Bai ◽  
Meng Zhang ◽  
...  
Keyword(s):  
Finite Time ◽  
Disturbance Rejection ◽  
High Performance ◽  
Control Strategies ◽  
Fractional Power ◽  
Critical Issue ◽  
Human Robot Interaction ◽  
Torque Control ◽  
Finite Time Stability ◽  
Control Scheme

SUMMARY Accurate torque control is a critical issue in the compliant human–robot interaction scenario, which is, however, challenging due to the ever-changing human intentions, input delay, and various disturbances. Even worse, the performances of existing control strategies are limited on account of the compromise between precision and stability. To this end, this paper presents a novel high-performance torque control scheme without compromise. In this scheme, a new nonlinear disturbance observer incorporated with equivalent control concept is proposed, where the faster convergence and stronger anti-noise capability can be obtained simultaneously. Meanwhile, a continuous fractional power control law is designed with an iteration method to address the matched/unmatched disturbance rejection and global finite-time convergence. Moreover, the finite-time stability proof and prescribed control performance are guaranteed using constructed Lyapunov function with adding power integrator technique. Both the simulation and experiments demonstrate enhanced control accuracy, faster convergence rate, perfect disturbance rejection capability, and stronger robustness of the proposed control scheme. Furthermore, the evaluated assistance effects present improved gait patterns and reduced muscle efforts during walking and upstair activity.

scholarly journals Comparative Study of Discrete Component Realizations of Fractional-Order Capacitor and Inductor Active Emulators

2018 ◽  
Vol 27 (11) ◽  
pp. 1850170 ◽  
Author(s):  
Georgia Tsirimokou ◽  
Aslihan Kartci ◽  
Jaroslav Koton ◽  
Norbert Herencsar ◽  
Costas Psychalinos
Keyword(s):  
Comparative Study ◽  
Fractional Order ◽  
High Performance ◽  
Continued Fraction ◽  
Transfer Functions ◽  
Operational Amplifiers ◽  
Current Conveyors ◽  
Continued Fraction Expansion ◽  
Current Feedback ◽  
Discrete Component

Due to the absence of commercially available fractional-order capacitors and inductors, their implementation can be performed using fractional-order differentiators and integrators, respectively, combined with a voltage-to-current conversion stage. The transfer function of fractional-order differentiators and integrators can be approximated through the utilization of appropriate integer-order transfer functions. In order to achieve that, the Continued Fraction Expansion as well as the Oustaloup’s approximations can be utilized. The accuracy, in terms of magnitude and phase response, of transfer functions of differentiators/integrators derived through the employment of the aforementioned approximations, is very important factor for achieving high performance approximation of the fractional-order elements. A comparative study of the accuracy offered by the Continued Fraction Expansion and the Oustaloup’s approximation is performed in this paper. As a next step, the corresponding implementations of the emulators of the fractional-order elements, derived using fundamental active cells such as operational amplifiers, operational transconductance amplifiers, current conveyors, and current feedback operational amplifiers realized in commercially available discrete-component IC form, are compared in terms of the most important performance characteristics. The most suitable of them are further compared using the OrCAD PSpice software.

Modeling of Mass-Spring-Damper System by Complex Stiffness Method

2014 ◽  
Vol 983 ◽  
pp. 420-423
Author(s):  
Sheng Guo Zhang ◽  
Xiao Ping Dang
Keyword(s):  
Transfer Functions ◽  
Mechanical Systems ◽  
Stiffness Method ◽  
In Series ◽  
Equivalent Complex ◽  
Mass Spring

This paper aims at directly modeling the transfer functions of mass-spring-damper systems. Using complex stiffness of mass, spring, and damper elements and equivalent complex stiffness of these elements in series and/or in parallel, the transfer functions of the mass-spring-damper systems are modeled quickly. This is very convenient to the modeling of the complicated mechanical systems.

Variable structure surge control for constant speed centrifugal compressors

2009 ◽  
Vol 17 (7) ◽  
pp. 815-833 ◽  
Author(s):  
Raef S. Shehata ◽  
Hussein A. Abdullah ◽  
Fayez F.G. Areed
Keyword(s):  
Variable Structure ◽  
Constant Speed ◽  
Centrifugal Compressors ◽  
Surge Control

Comparison of Motion Characteristics of High Performance CNC Rotary Tables

2010 ◽  
Author(s):  
Muditha K. M. Dassanayake ◽  
Masaomi Tsutsumi
Keyword(s):  
High Performance ◽  
Closed Loop ◽  
Friction Torque ◽  
Step Response ◽  
Rotary Table ◽  
Direct Drive ◽  
Drive Motor ◽  
Fluctuation Frequency ◽  
Motion Characteristics ◽  
Accuracy And Repeatability

In this paper, the motion performances of the two rotary tables which are driven by roller gear cam and direct drive motor are measured and compared. The table with roller gear cam was controlled in semi-closed loop and full-closed loop methods while the other was controlled only in full-closed loop method. In the measurements, the positioning accuracy and repeatability, rotational fluctuation, frequency response, step response and etc of the systems were measured. All these tests were carried out without any kind of compensation methods such as pitch error or cogging torque compensation etc. Three rotary encoders for rotary table with roller gear cam and one rotary encoder for rotary table with direct drive motor were used for measurements. Furthermore, the simulations were carried out by mathematical models and the results were compared with measured results. The comparison shows that the measured and simulated results have a good agreement. From the simulation results, the friction torque was identified and also compared. The results imply that though both the tables show high performances, the performances of the rotary table driven by roller gear cam are comparatively higher than that of rotary table driven by direct drive motor.

scholarly journals Determination of (–)-Quinine and (+)-Quinidine by Liquid Chromatography with Diode-Laser Polarimetric Detection

1999 ◽  
Vol 82 (6) ◽  
pp. 1308-1315 ◽  
Author(s):  
Francisco García Sánchez ◽  
Aurora Navas Díaz ◽  
Angeles García Pareja ◽  
Germán Cabrera Montiel
Keyword(s):  
Liquid Chromatography ◽  
Diode Laser ◽  
Mobile Phase ◽  
High Performance ◽  
Dynamic Range ◽  
Reversed Phase ◽  
Rabbit Serum ◽  
In Series ◽  
Phase Column

Abstract High-performance liquid chromatography using a combination of photometric, fluorimetric, and diode-laser polarimetric detectors in series for the determination of (+)-quinidine and (–)-quinine was investigated. An RP-8 reversed-phase column and methanol-water (80 + 20, v/v) with 0.2% triethylamine as mobile phase at a flow rate of 1 mL/min were used. A dynamic range of 0-200 μg for (+)-quinidine and (+)-quinine was established, with detection limits of 17.0 and 16.7 μg, respectively. An application of this method in spiked rabbit serum was developed.

scholarly journals Modeling and Controlling the Cooling System of an IC Vehicle

2021 ◽  
pp. 80-85
Author(s):  
C. Mureșan ◽  
◽  
G. Harja
Keyword(s):  
Mathematical Modeling ◽  
Heat Exchangers ◽  
High Performance ◽  
Cooling System ◽  
Control Strategies ◽  
Positive Influence ◽  
Control Algorithms ◽  
Performance Control ◽  
Ic Engines ◽  
Physical Phenomena

The performance and efficiency of internal combustion (IC) engines can be greatly improved by using a high-performance cooling system. This can be achieved by implementing robust control strategies and, also by building the cooling system with high-performance elements. The mechanical execution elements can be replaced with electrically controllable elements such as the pump and the thermostat valve. This will have a positive influence on the degree of controllability of the system. In order to develop high-performance control algorithms, it is necessary to have a model that best reflects the behaviors of the physical system. Thus, this paper presents a mathematical modeling approach for the cooling system using the principles of heat exchangers and the physical phenomena present in them.

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