Effect of Internal Leakage on an Electro-Hydraulic Servo-Driven Control Valve Performance

2011 ◽  
Vol 99-100 ◽  
pp. 901-905 ◽  
Author(s):  
Yu Dong Xie ◽  
Yan Jun Liu ◽  
Yong Wang
Keyword(s):  
Control Valve ◽  
Mathematic Model ◽  
Combined Cycle ◽  
Mixed Gas ◽  
Control Effect ◽  
Dead Band ◽  
Hydraulic Servo ◽  
The Dead ◽  
Valve Control ◽  
Control Accuracy

The principle of an electro-hydraulic servo-driven control valve used to regulate mixed-gas pressure in combined cycle power plant is introduced. The mathematic model for describing the dead-band characteristics of the electro-hydraulic servo-driven control valve is built. The effect of driving system leakage of the control valve on the performances of the control valve is analyzed. The results show that the dead band of the electro-hydraulic servo-driven control valve increases with the rise of the system leakage, the leakage affects the response rapidity and the control accuracy of the control valve, and the valve control effect on the pressure pulsation of the mixed gas decreases with the increase of the system leakage.

scholarly journals Unsteady Analyses of a Control Valve due to Fluid-Structure Coupling

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Yudong Xie ◽  
Yong Wang ◽  
Yanjun Liu ◽  
Fang Cao ◽  
Yongcheng Pan
Keyword(s):  
Power Plants ◽  
Natural Frequencies ◽  
Oscillation Amplitude ◽  
Control Valve ◽  
Combined Cycle ◽  
Coupling Mechanism ◽  
Mixed Gas ◽  
Fluid Structure ◽  
Valve Opening ◽  
Low Order

Control valves play important roles in the control of the mixed-gas pressure in the combined cycle power plants (CCPP). In order to clarify the influence of coupling between the structure and the fluid system at the control valve, the coupling mechanism was presented, and the numerical investigations were carried out. At the same operating condition in which the pressure oscillation amplitude is greater when considering the coupling, the low-order natural frequencies of the plug assembly of the valve decrease obviously when considering the fluid-structure coupling action. The low-order natural frequencies at 25% valve opening, 50% valve opening, and 75% valve opening are reduced by 11.1%, 7.0%, and 3.8%, respectively. The results help understand the processes that occur in the valve flow path leading to the pressure control instability observed in the control valve in the CCPP.

Rollback and Compensation for an Easy Control Hydraulic Servo Joint

2013 ◽  
Vol 312 ◽  
pp. 662-666
Author(s):  
Xiao Hong Jin ◽  
Xian Bao Xiang ◽  
Lin Jiang ◽  
Qin Fen Miao
Keyword(s):  
Mathematic Model ◽  
Basic Structure ◽  
Dynamic Responses ◽  
Hydraulic Servo ◽  
Working Principle ◽  
Reconfigurable Robot ◽  
Input Element ◽  
And Control ◽  
Double Orifice ◽  
Control Accuracy

The easy control hydraulic servo joint is a key element for a reconfigurable robot and its response and control accuracy determine the performance of the robot. With the stepping motor as the input element the main parts of joint includes a rotational valve with the double orifice and the single-vane actuator. The basic structure and the working principle of joint are introduced. The mathematic model is established and the dynamic responses are analysed by using the digit simulation. From the results of simulation, a phenomenon of rollback in the process of response of joint is observed. With the simulation, the relationships between the rollback and parameters of structure are discussed. A digit PID controller is employed to reduce the effect of rollback to a great extent.

A dead-band model and its online detection for the pilot stage of a two-stage directional flow control valve

2015 ◽  
Vol 230 (4) ◽  
pp. 639-654 ◽  
Author(s):  
Bing Xu ◽  
Qi Su ◽  
Junhui Zhang ◽  
Zhenyu Lu
Keyword(s):  
Flow Control ◽  
Control Valve ◽  
Band Model ◽  
Time Interval ◽  
Short Time Interval ◽  
Online Detection ◽  
Two Stage ◽  
Dead Band ◽  
Directional Flow ◽  
The Dead

The dead-band in the electro-hydraulic proportional control valve is one of the main factors that affect its dynamic performance. Especially in the pilot stages of two-stage directional flow control valves, the insistent dead-band will result in a conservative valve controller design. In this paper, a detailed dead-band model describing the relationship between pilot valve spool and the flow rate of the pilot control valve is proposed. And an improved dead-band description involved with the housing clearance of the valve spool is developed to prove the dead-band uncertainty for a single valve system. Then a simple and effective method is proposed to detect the varying dead-band values in the pilot stage. This method is specially designed with a limited main spool displacement and short time interval so that it can be used for online detection without affecting the hydraulic system where the two-stage valve is involved. With the regular dead-band inverse function, comparative experimental results show that this method is effective to attenuate the large trajectory tracking error caused by the varying dead-band. This dead-band detection also can be applied to other electro-hydraulic proportional valve-controlled position control systems with unknown dead-bands.

Design and Analysis of a Two-Valve Control Hydraulic System for Controllable Pitch Propeller

2012 ◽  
Vol 468-471 ◽  
pp. 122-126
Author(s):  
Chang Jun Zhang ◽  
Jing Li ◽  
Hong Gang Jiang ◽  
Yun Chen ◽  
Yao Bao Yin
Keyword(s):  
Hydraulic System ◽  
Simulation Analysis ◽  
Control Valve ◽  
Proportional Valve ◽  
Directional Control ◽  
Parallel Control ◽  
The Relationship ◽  
Valve Control ◽  
Control Accuracy ◽  
Directional Control Valve

This paper designs a two-valve control hydraulic system for controllable pitch propeller which consists of an electro-hydraulic directional control valve and a proportional directional control valve. The parallel control strategy is proposed and respective controllers are determined for the system. It yields out the relationship between the control parameters and valves characteristics by modeling and simulation analysis. Also the influence of the proportional valve flow rate on pitch control accuracy is discussed.

Prediction Model of Control Valve Characteristics

2012 ◽  
Vol 605-607 ◽  
pp. 1345-1349
Author(s):  
Yu Dong Xie ◽  
Yan Jun Liu ◽  
Yong Wang
Keyword(s):  
Fluid Flow ◽  
Dynamic Performance ◽  
Control Valve ◽  
Flow Regulation ◽  
Combined Cycle ◽  
Quality And Safety ◽  
Hydraulic Control ◽  
Mixed Gas ◽  
Mathematical Simulations ◽  
Process Output

Control valves are generally present whenever fluid flow regulation is required. The control valve reliability is critical to the control quality and safety of a plant. An improved dynamic and static valve behaviour would have a major impact on the process output. In order to assess the dynamic performance of the control valve, a computer model of an electro-hydraulic control valve is developed. And the control valve characteristics are investigated through the use of mathematical simulations of the control valve dynamic performance. The results show that the electro-hydraulic driven control valve, which is developed to regulate the mixed-gas pressure in combined cycle power plant, can meet the challenge of the gas turbine.

Design and Analysis of a Flow-Control Valve With Controllable Pressure Compensation Capability for Mobile Machinery

2021 ◽  
Author(s):  
Bo Wang ◽  
Yunwei Li ◽  
Long Quan ◽  
Lianpeng Xia
Keyword(s):  
Pressure Drop ◽  
Flow Control ◽  
Pressure Difference ◽  
Control Valve ◽  
Flow Control Valve ◽  
Continuous Control ◽  
Small Flow ◽  
Pressure Compensation ◽  
Force Compensation ◽  
Control Accuracy

Abstract There are the problems in the traditional pressure-compensation flow-control valve, such as low flow control accuracy, small flow control difficulty, and limited flow range. For this, a method of continuous control pressure drop Δprated (i.e. the pressure drop across the main throttling orifice) to control flow-control valve flow is proposed. The precise control of small flow is realized by reducing the pressure drop Δprated and the flow range is amplified by increasing pressure drop Δprated. At the same time, it can also compensate the flow force to improve the flow control accuracy by regulating the pressure drop Δprated. In the research, the flow-control valve with controllable pressure compensation capability (FVCP) was designed firstly and theoretically analyzed. Then the sub-model model of PPRV and the joint simulation model of the FVCP were established and verified through experiments. Finally, the continuous control characteristics of pressure drop Δprated, the flow characteristics, and flow force compensation were studied. The research results demonstrate that, compared with the traditional flow-control valve, the designed FVCP can adjust the compensation pressure difference in the range of 0∼3.4 MPa in real-time. And the flow rate can be altered within the range of 44%∼136% of the rated flow. By adjusting the compensation pressure difference to compensate the flow force, the flow control accuracy of the multi-way valve is improved, and the flow force compensation effect is obvious.

The Modeling and Control of the Hydraulic Servo System by Using On-Off Valve

2000 ◽  
Author(s):  
Xuanyin Wang
Keyword(s):  
Servo System ◽  
Mathematic Model ◽  
Hydraulic Cylinder ◽  
Servo Control ◽  
Linear Quadratic ◽  
Modeling And Control ◽  
Hydraulic Servo ◽  
Self Tuning ◽  
Hydraulic Servo System ◽  
And Control

Abstract This paper researches on the hydraulic servo system by using ordinary on-off valves. The mathematic model of an asymmetric hydraulic cylinder servo control system is built, and its characteristic is analysed here. To reduce the static and dynamic characteristic differences between forward and reverse motion of asymmetric cylinder, and improve system’s performance, a self-tuning linear quadratic gaussian optimum controller (SLQG) is designed successful. In the end, an asymmetric hydraulic cylinder servo system of paint robot is researched. The result shows that the above method is effective.

The Dead Band Control of LTC Transformer at Distribution Substation

2009 ◽  
Vol 24 (1) ◽  
pp. 319-326 ◽  
Author(s):  
Joon-Ho Choi ◽  
Seung-Il Moon
Keyword(s):  
Dead Band ◽  
The Dead

scholarly journals AMT SOUNDINGS IN THE DEAD BAND WITHIN THE CHUKOTKA REGION (RUSSIAN FAR EAST)

2019 ◽  
Vol 236 (2) ◽  
pp. 125-132
Author(s):  
E. Yu. Ermolin ◽  
◽  
O. Ingerov ◽  
A. A. Yankilevich ◽  
N. N. Pokrovskaya ◽  
...  
Keyword(s):  
Russian Far East ◽  
Far East ◽  
Dead Band ◽  
The Dead
Sign in / Sign up

Export Citation Format

Share Document