Controlling Flow Rate and Fluid Level by Variable Frequency Drive Unit

2010 ◽  
Vol 57 (4) ◽  
pp. 393-404
Author(s):  
Riza Gürbüz
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
Control Unit ◽  
Control Flow ◽  
Variable Frequency ◽  
Motor Speed ◽  
Fluid Level ◽  
Drive Unit ◽  
Variable Frequency Drive ◽  
Ac Drive

Controlling Flow Rate and Fluid Level by Variable Frequency Drive Unit The Variable Frequency Drive (VFD) is used to control the speed of the pumpmotor to attain the desired flow rate and fluid level in a fluid system. An AC drive provides efficient flow control by varying the pump-motor speed. The comparison of energy requirements and costs in a system where a throttling device is used for flow control on a centrifugal pump with the power used when an variable frequency drive (VFD) is used to control the same flow, evidently shows potential savings. In this system, AC Motor Frequency drive and static pressure transmitter, turbine type flowmeter and Analog/Digital cards, micro-control unit and computer connection are designed specially to control flow rate, fluid flow type (turbulence or laminar) and water level at the different conditions with different PID parameters.

Modeling and Optimal Control of a Variable-Speed Centrifugal Pump With a Pipeline

2016 ◽  
Author(s):  
Cristian F. Jaimes Saavedra ◽  
Sebastian Roa Prada ◽  
Jessica G. Maradey Lázaro
Keyword(s):  
Mathematical Model ◽  
Control System ◽  
Flow Control ◽  
Flow Rate ◽  
Power Efficiency ◽  
Control Valve ◽  
Operating Point ◽  
Variable Frequency ◽  
Centrifugal Pumps ◽  
Variable Frequency Drive

Pumping processes often require different operating conditions for the same pipeline. The conditions downstream in the pipeline can change in such a way that the pressure at the discharge of the pump may vary, which automatically introduces changes in the flow supplied by the pump into the pipeline due to the head vs flow characteristic curve of the pump. Even under varying pipeline pressure conditions, it may be necessary to keep the flow discharge of the pump constant. The two most commonly used control strategies for flow control with centrifugal pumps are by means of a fixed-speed pump and a control valve at the outlet of the pump, or by means of a variable frequency drive which avoids the need for the control valve. It has been demonstrated that the approach with the fixed-speed pump and the control valve provides poor power efficiency results, so a variable frequency drive is normally the solution of choice in industry applications. The use of a variable frequency drive allows reaching the flow required by the system without changing the physical characteristic of the pump or pipeline, i.e., it is not necessary to shut the system down to replace the impeller of the pump. However, affinity laws of centrifugal pumps dictate that a change in the rotational speed of the impeller shifts the characteristic curves of the pump, not only the flow vs head curve, but also the efficiency curves, among others. Besides, searching for a different operating point by changing the speed of the pump does not necessarily guarantees optimal operating power efficiency. This paper proposes an optimization approach where a compromise is made between flow control and power efficiency by minimizing the error in the flow rate while at the same time maximizing the power efficiency. To accomplish this goal, this paper presents the modeling of the pump and pipeline, and the design of a linear quadratic regulator control for the fluid flow passing through a given pipeline. The fluid under consideration is water. The mathematical model of the overall system is derived by considering the model of an AC motor, the pump and the hydraulic circuit. Then, with the help of the software MATLAB, the controller was designed and implemented with the linearized mathematical model. The actuator of the control system is the variable frequency drive that changes the speed of the impeller to adjust the flow rate to the required operating point under different loading conditions. The results show the behavior of the compensated system with the optimal controller. In practice, the control system must take into account the constraints of the control effort, which means, the frequency of the pump must be kept within safe values to achieve proper functioning of the pumping system.

scholarly journals The Characteristic of Variable Frequency Drive for Water Flow Control in the SFC Plant

2021 ◽  
Vol 7 (1) ◽  
pp. 6
Author(s):  
Sefi Novendra Patrialova ◽  
Destiarga Husein Wardhana ◽  
Lucky Putri Rahayu ◽  
Tedy Agasta
Keyword(s):  
Flow Control ◽  
Water Flow ◽  
Variable Frequency ◽  
Variable Frequency Drive

scholarly journals Experimental Investigations of Instantaneous Angular Speeds and Torsional Vibration in an AC Motor Driven Rotor System Involving a Variable Frequency Drive

2021 ◽  
Author(s):  
Mina Nozohouri
Keyword(s):  
Torsional Vibration ◽  
Dynamical Behavior ◽  
Experimental Investigations ◽  
Variable Frequency ◽  
Motor Speed ◽  
Variable Frequency Drive ◽  
Arrival Times ◽  
Wide Range ◽  
Complex Motor ◽  
Ac Induction Motor

Torsional vibration of a complex electro-mechanical system consisting of a VFD controller and AC induction motor is investigated in this thesis to study the dynamical behavior of a rather complex motor drive, used to power a DC generator and a set of heat-generation resistors for achieving various levels of nominal loads over a wide range of nominal frequencies/speeds. Two magnetic encoders are placed at two locations to record the arrival times of two arrays of teeth in connection with a data acquisition system. Through a Matlab-coded algorithm, the instantaneous angular speeds and their harmonic compositions up to 16th order of the mean motor speed can be accurately discerned. The model and the algorithms developed in this thesis can be used in a variety of machines and testing systems powered by induction motors and regulated by variable-frequency-drive controllers for design, condition monitoring and identification of sources of noise and disastrous vibration.

scholarly journals Experimental Investigations of Instantaneous Angular Speeds and Torsional Vibration in an AC Motor Driven Rotor System Involving a Variable Frequency Drive

2021 ◽  
Author(s):  
Mina Nozohouri
Keyword(s):  
Torsional Vibration ◽  
Dynamical Behavior ◽  
Experimental Investigations ◽  
Variable Frequency ◽  
Motor Speed ◽  
Variable Frequency Drive ◽  
Arrival Times ◽  
Wide Range ◽  
Complex Motor ◽  
Ac Induction Motor

Torsional vibration of a complex electro-mechanical system consisting of a VFD controller and AC induction motor is investigated in this thesis to study the dynamical behavior of a rather complex motor drive, used to power a DC generator and a set of heat-generation resistors for achieving various levels of nominal loads over a wide range of nominal frequencies/speeds. Two magnetic encoders are placed at two locations to record the arrival times of two arrays of teeth in connection with a data acquisition system. Through a Matlab-coded algorithm, the instantaneous angular speeds and their harmonic compositions up to 16th order of the mean motor speed can be accurately discerned. The model and the algorithms developed in this thesis can be used in a variety of machines and testing systems powered by induction motors and regulated by variable-frequency-drive controllers for design, condition monitoring and identification of sources of noise and disastrous vibration.

scholarly journals Redesain Speed Control Submerged Scraper Conveyor (Ssc) Bottom Ash Menggunakan Ac Drive

2020 ◽  
Vol 2 (1) ◽  
pp. 39-53
Author(s):  
Fahrizal Reza ◽  
Ilmi Rizki Imaduddin
Keyword(s):  
Fly Ash ◽  
Local Control ◽  
Bottom Ash ◽  
Speed Control ◽  
Spare Part ◽  
Motor Drive ◽  
Variable Frequency ◽  
Variable Frequency Drive ◽  
Ac Drive ◽  
Machine Interface

Sistem kontrol penggerak Submerged Scrapper Conveyor (SSC) mempunyai peran yang sangat vital dalam proses kerja transportasi material limbah abu berat (bottom-ash) yang merupakan sisa hasil pembakaran batubara di boiler. Sistem kontrol penggerak SSC bekerja secara kontinyu 24 jam untuk menjaga agar material bottom ash tidak menumpuk di boiler hopper . Sistem ini harus selalu dijaga kehandalannya, karena apabila bermasalah maka akan berdampak langsung pada keberlangsungan operasi boiler di pembangkit yaitu menyebabkan derating.Sistem kontrol penggerak eksisting pada SSC menggunakan speed variator. Speed variator bekerja secara mekanis untuk mengatur kecepatan dari SSC yaitu dengan sistem hidrolik transmisi. Kecepatan perlu diatur untuk mengendalikan laju material bottom ash akibat variasi beban pembangkit. Apabila beban tinggi, maka material bottom ash akan lebih banyak dibanding pada beban rendah. Sistem penggerak SSC di PLTU Paiton Unit 1 dan 2 dengan speed variator dewasa ini banyak mengalami permasalahan. Mulai dari overheating, kerusakan inner part, hingga spare part yang sudah tidak tersedia (obsolete), selain itu penurunan nilai kalori batubara yang dipakai pada boiler juga menambah beban pada SSC dikarenakan limbah bottom ash yang semakin banyak.Untuk memaksimalkan kehandalan SSC di PLTU Paiton, maka dilakukan redesain speed control SSC. Redesain ini dilakukan dengan mengganti sistem kontrol penggerak SSC yang lama, yaitu speed variator dengan VFD (variable frequency drive) atau motor drive AC (Alternating Current). Redesain tersebut terdiri dari beberapa tahap, antara lain: (i) melakukan  penggantian peralatan pada sistem kontrol penggerak SSC antara lain motor SSC serta mengganti speed variator dengan VFD, (ii) memodifikasi wiring  dan logic  pada PLC sistem untuk mengontrol kecepatan SSC, (iii) melakukan modifikasi panel kontrol sehingga operasi SSC dapat dimonitor di CCR Fly Ash HMI Human Machine Interface dan local control station baik secara auto atau lokal.

scholarly journals The Acoustical Behavior of Contra-Rotating Fan

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Juan Wu ◽  
Ziming Kou ◽  
Jing Liu
Keyword(s):  
Flow Rate ◽  
Sound Pressure ◽  
Noise Source ◽  
Low Frequency ◽  
Pressure Level ◽  
Working Environment ◽  
Variable Frequency ◽  
Axial Distance ◽  
Major Contributor ◽  
Variable Frequency Drive

The noise produced by a contra-rotating ventilator can cause injury to humans. Therefore, it is important to reduce noise caused by ventilators. In this study, the Ffowcs Williams and Hawkings (FW-H) model was used to simulate the acoustics of four different axial impeller spacing points based on the unsteady flow field through a FBD No. 8.0 contra-rotating ventilator. Experiments were conducted to verify the correctness of the numerical model. Meanwhile, the Variable Frequency Drive (VFD) drives the two motors of 55 kW to give the impellers different speeds to distinguish different conditions. The results showed that the main noise source of the ventilator was the two rotating impellers and the area between them. For the same axial space, the noise decreased with the increase of flow rate and then decreased. And the amplitude of the discrete pulse increased gradually. It can be concluded that the vortex acoustics decreased gradually with the increase of flow rate and the rotating acoustics were the major contributor. With the axial distance increasing, the noise caused by the two impellers was weak, and the frequencies of sound pressure level moved toward medium- and low-frequency bands gradually. The suitable axial space could reduce noise and improve the working environment.

The MAESFLO Device: A Complete Microfluidic Control System

2009 ◽  
Vol 1191 ◽  
Author(s):  
Jacques Goulpeau ◽  
Vélan Taniga ◽  
Charles-André Kieffer
Keyword(s):  
Response Time ◽  
Flow Control ◽  
High Precision ◽  
Flow Rate ◽  
Network Architecture ◽  
Size Control ◽  
Pressure Control ◽  
Control Flow ◽  
Short Response Time ◽  
Micro Channels

AbstractIn spite of considerable efforts, flow control in micro-channels remains a challenge owing to the very small ratio of channel/supply-system volumes, as well as the induction of spurious flows by extremely small pressure or geometry changes. We present here a robust and complete system for flow control in complex microchannel network that both monitors and controls all the flow relevant parameters, that is to say flow rate and pressure. Based on a dynamic control of reservoir pressures at the end of each channel and external thermal flow-sensors, all the parameters are measured with a precision down to 25 μBar and 2nL/min. Thanks to adaptative feed back control loop, the MAESFLO can control either the flow rate or the pressure with high stability over long period whatever the microsystem characteristics. Compared to classic pumps, a significant increase of stability has been reached as no mechanical parts are involved. Indeed the flow rate is pulse free and is stable down to 0.1% of the full scale. Besides, pressure control enables to achieve short response time (less than hundreds of millisec). The MAESFLO is thus a unique system to control flow in complex network architecture and can be considered as an alternative to integrated micro-valves using only external equipments. Indeed, the MAESFLO can stop the flow to nearly zero in one or several branches of a complex microfluidic network while keeping other flows constant. Sequential manipulation of liquids in a definite part of a micro-device is thus possible without expensive and time consuming fabrication processes. It can be particularly useful when dealing with washing steps in the case of biological assay for example. Controlling flow with short response time along with high precision is also a key issue in microfluidic. By combining pressure actuation with flowrate monitoring, short response time are achievable keeping a high precision flow rate. It can be particularly useful for droplet generation and size control, droplet on demand generation, long time living cell perfusion and drug injection… In this work we will present the benefit to control and monitor both pressure and flow rate with the MAESFLO. A lot of information can be extracted from these simple parameters, as hydraulic resistance, monophasic and biphasic apparent viscosity, the volume and the position of a trapped air bubble and many more. The proof of concept of stop flow control will also be shown with experimental results stressing the advantages of the “virtual micro-valve”.

scholarly journals On the Fictitious Grease Lubrication Performance in a Four-Ball Tester

Lubricants ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 33
Author(s):  
Sravan K. Joysula ◽  
Anshuman Dube ◽  
Debdutt Patro ◽  
Deepak Halenahally Veeregowda
Keyword(s):  
Critical Factor ◽  
Maximum Load ◽  
Test Method ◽  
Extreme Pressure ◽  
Motor Speed ◽  
Low Friction ◽  
Grease Lubrication ◽  
Additive Package ◽  
Variable Frequency Drive ◽  
Lubrication Performance

The extreme pressure (EP) behavior of grease is related to its additives that can prevent seizure. However, in this study following ASTM D2596 four-ball test method, the EP behavior of greases was modified without any changes to its additive package. A four-ball tester with position encoders and variable frequency drive system was used to control the speed ramp up time or delay in motor speed to demonstrate higher grease weld load and lower grease friction that were fictitious. A tenth of a second delay in speed ramp up time had showed an increase in the weld load from 7848 N to 9810 N for grease X and 6082 N to 9810 N for grease Y. Further increase in the speed ramp up time to 0.95 s showed that the greases passed the maximum load of 9810 N that was possible in the four-ball tester without seizure. The mechanism can be related to the delay in rise of local temperature to reach the melting point of steel required for full seizure or welding, that was theoretically attributed to an increase in heat loss as the speed ramp-up time was increased. Furthermore, the speed ramp up time increased the corrected load for grease X and Y. This resulted in lower friction for grease X and Y. This fictitious low friction can be attributed to decrease in surface roughness at higher extreme pressure or higher corrected load. This study suggests that speed ramp up time is a critical factor that should be further investigated by ASTM and grease manufacturers, to prevent the use of grease with fictitious EP behavior.

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