Transient Flow Simulation in Natural Gas Pipelines Using the State Space Model

2010 ◽  
Author(s):  
M. Behbahani-Nejad ◽  
A. Ghanbarzadeh ◽  
R. Alamian
Keyword(s):  
Finite Difference ◽  
State Space ◽  
Transient Flow ◽  
Transfer Functions ◽  
State Space Model ◽  
Method Of Lines ◽  
Flow Simulation ◽  
The State ◽  
Finite Difference Schemes ◽  
Gas Pipelines

A transient flow simulation for gas pipelines and networks is proposed. The proposed transient flow simulation is based on the state space equations. The equivalent transfer functions of the nonlinear governing equations are derived for different boundary conditions types. Next, the state space equations are derived from the transfer functions. To verify the accuracy of the proposed simulation, the results obtained are compared with those of the conventional finite difference schemes (such as total variation diminishing algorithms, method of lines, and other finite difference implicit and explicit schemes). The effect of the flow inertia is incorporated in this simulation. The accuracy and computational efficiency of the proposed method are discussed for a single gas pipeline and a sample gas network.

scholarly journals A New Lumped Parameter Model for Natural Gas Pipelines in State Space

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1971 ◽  
Author(s):  
Kai Wen ◽  
Zijie Xia ◽  
Weichao Yu ◽  
Jing Gong
Keyword(s):  
Natural Gas ◽  
State Space ◽  
Transient Flow ◽  
Transfer Functions ◽  
The State ◽  
Lumped Parameter Model ◽  
Actual Behavior ◽  
Gas Pipelines ◽  
Computational Point ◽  
Lumped Parameter

Many algorithms and numerical methods, such as implicit and explicit finite differences and the method of characteristics, have been applied for transient flow in gas pipelines. From a computational point of view, the state space model is an effective method for solving complex transient problems in pipelines. However, the impulse output of the existing models is not the actual behavior of the pipeline. In this paper, a new lumped parameter model is proposed to describe the inertial nature of pipelines with inlet/outlet pressure and flow rate as outer variables in the state space. Starting from the basic mechanistic partial differential equations of the general one-dimensional compressible gas flow dynamics under isothermal conditions, the transfer functions are first acquired as the fundamental work. With Taylor-expansion and a transformation procedure, the inertia state space models are derived with proper simplification. Finally, three examples are used to illustrate the effectiveness of the proposed model. With the model, a real-time automatic scheduling scheme of the natural gas pipeline could be possible in the future.

scholarly journals The Cascade Control of Natural Gas Pipeline Systems

2019 ◽  
Vol 9 (3) ◽  
pp. 481
Author(s):  
Kai Wen ◽  
Jing Gong ◽  
Yan Wu
Keyword(s):  
Natural Gas ◽  
Control Theory ◽  
State Space ◽  
State Space Model ◽  
The State ◽  
Gas Pipeline ◽  
Cascade Control ◽  
Gas Pipelines ◽  
Space Model ◽  
Natural Gas Pipelines

With the boost of natural gas consumption, an automatic gas pipeline scheduling method is required to replace the dispatchers in decision making. Since the state space model is the fundamental work of modern control theory, it is possible that the classical controller synthesis method can be used for the complicated gas pipeline controller design. In this paper, a cascade control algorithm is proposed based on the state space model that is used for the transient flow simulation of the natural gas pipelines. A linear quadratic regulator is designed following the classical optimal control theory. Finally, the transient process with different control methods shows the effectiveness of the cascade control using information of the entire pipeline. According to the hardware configuration of natural gas pipelines, automatic scheduling process is ready to deploy as one step to the intelligent natural gas pipelines.

Dynamic Analysis of a Torsional MEMS Scanner Mirror: Part 1 — Disturbance Analysis Framework

2005 ◽  
Author(s):  
Faik Can Meral ◽  
Ipek Basdogan
Keyword(s):  
State Space ◽  
Transfer Functions ◽  
State Space Model ◽  
Time Domain Analysis ◽  
The State ◽  
Space Representation ◽  
Modeling And Analysis ◽  
Lyapunov Approach ◽  
State Space Representation ◽  
Disturbance Analysis

Future optical micro systems such as Micro Electro Mechanical Systems (MEMS) scanners and micro-mirrors will extend the resolution and sensitivity offered by their predecessors. These systems face the challenge of achieving nanometer precision subjected to various disturbances. Predicting the performance of such systems early in the design process can significantly impact the design cost and also improve the quality of the design. Our approach aims to predict the performance of such systems under various disturbance sources and develop a generalized design approach for MEMS structures. In this study, we used ANSYS for modeling and analysis of a torsional MEMS scanner mirror. ANSYS modal analysis results, which are eigenvalues (natural frequencies) and eigenvectors (modeshapes), are used to obtain the state space representation of the mirror. The state space model of the scanner mirror was reduced using various reduction techniques to eliminate the states that are insignificant for the transfer functions of interest. The results of these techniques were compared to obtain the best approach to obtain a lower order model that still contains all of the relevant dynamics of the original model. After the model size is reduced significantly, a disturbance analysis is performed using Lyapunov approach to obtain root-mean-square (RMS) values of the mirror rotation angle under the effect of a disturbance torque. The Lyapunov approach results were validated using a time domain analysis.

Design Methodology for Microelectromechanical Systems. Case Study: Torsional Scanner Mirror

2006 ◽  
Vol 129 (10) ◽  
pp. 1023-1030 ◽  
Author(s):  
Faik Can Meral ◽  
Ipek Basdogan
Keyword(s):  
State Space ◽  
Microelectromechanical Systems ◽  
Transfer Functions ◽  
State Space Model ◽  
The State ◽  
Mode Shapes ◽  
Design Parameters ◽  
Space Representation ◽  
Disturbance Analysis ◽  
Disturbance Torque

Future optical microsystems, such as microelectromechanical system (MEMS) scanners and micromirrors, will extend the resolution and sensitivity offered by their predecessors. These systems face the challenge of achieving nanometer precision subjected to various disturbances. Predicting the performance of such systems early in the design process can significantly impact the design cost and also improve the quality of the design. Our approach aims to predict the performance of such systems under various disturbance sources and develop a generalized design approach for MEMS structures. In this study, we used ANSYS for modeling and dynamic analysis of a torsional MEMS scanner mirror. ANSYS modal analysis results, which are eigenvalues (natural frequencies) and eigenvectors (mode shapes), are used to obtain the state-space representation of the mirror. The state-space model of the scanner mirror was reduced using various reduction techniques to eliminate the states that are insignificant for the transfer functions of interest. The results of these techniques were compared to obtain the best approach to obtain a lower order model that still contains all the relevant dynamics of the original model. After the model size is reduced significantly, a disturbance analysis is performed using Lyapunov approach to obtain root-mean-square values of the mirror rotation angle under the effect of a disturbance torque. The magnitude levels of the disturbance torque are obtained using an experimental procedure. The disturbance analysis framework is combined with the sensitivity analysis to determine the critical design parameters for optimizing the system performance.

Modeling of CCLP in koryo extract production

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ji Chol ◽  
Ri Jun Il
Keyword(s):  
Process Control ◽  
Medical Care ◽  
State Space ◽  
State Space Model ◽  
The State ◽  
Space Model ◽  
Effective Components ◽  
Counter Current

Abstract The modeling of counter-current leaching plant (CCLP) in Koryo Extract Production is presented in this paper. Koryo medicine is a natural physic to be used for a diet and the medical care. The counter-current leaching method is mainly used for producing Koryo medicine. The purpose of the modeling in the previous works is to indicate the concentration distributions, and not to describe the model for the process control. In literature, there are no nearly the papers for modeling CCLP and especially not the presence of papers that have described the issue for extracting the effective components from the Koryo medicinal materials. First, this paper presents that CCLP can be shown like the equivalent process consisting of two tanks, where there is a shaking apparatus, respectively. It allows leachate to flow between two tanks. Then, this paper presents the principle model for CCLP and the state space model on based it. The accuracy of the model has been verified from experiments made at CCLP in the Koryo Extract Production at the Gang Gyi Koryo Manufacture Factory.

Outlier detection in the state space model

1994 ◽  
Vol 20 (2) ◽  
pp. 143-148 ◽  
Author(s):  
Siddhartha Chib ◽  
Ram C. Tiwari
Keyword(s):  
State Space ◽  
Outlier Detection ◽  
State Space Model ◽  
The State ◽  
Space Model

Motion Response Control of the DWSC Spar Based on State-Space Model

2012 ◽  
Author(s):  
Xiaochuan Yu ◽  
Jeffrey Falzarano
Keyword(s):  
State Space ◽  
Transfer Functions ◽  
State Space Model ◽  
Development Program ◽  
Naval Research ◽  
Hydrodynamic Coefficients ◽  
Time Step ◽  
Response Control ◽  
Motion Response ◽  
Space Model

In 2007, the Office of Naval Research (ONR) started a technology development program called STLVAST (Small to Large Vessel At-Sea Transfer), in order to develop ‘enabling capabilities’ in the realm of logistic transfer (i.e. stores, equipment, vehicles) between a large transport vessel and a smaller T-craft ship, using a Deep Water Stable Crane (DWSC) spar between them. In this paper, the equation of motions of the single DWSC spar is initially expressed as the standard state-space model. Then the ODE solver of Matlab is directly employed to obtain the motion responses at each time step. Two levels of approximation of hydrodynamic coefficients are considered in this study. One is the Constant Coefficient Method (CCM), and the other one is the Impulse Response Function (IRF) method, with fluid memory effects considered. WAMIT software is used to calculate the hydrodynamic coefficients, including the added mass, radiation damping, IRF, the first order and second order waves loads transfer functions, etc. The motion response control is achieved by assuming the thrusters can provide the optimal feedback force derived from Linear Quadratic Regulator (LQR) method.

Optimal State-Space Control of a Gas Turbine Engine

1992 ◽  
Vol 114 (4) ◽  
pp. 763-767 ◽  
Author(s):  
J. W. Watts ◽  
T. E. Dwan ◽  
C. G. Brockus
Keyword(s):  
State Space ◽  
Gas Turbine ◽  
State Space Model ◽  
Gas Turbine Engine ◽  
The State ◽  
Operating Conditions ◽  
Turbine Engine ◽  
Analog Control ◽  
Linear State ◽  
High Level

An analog fuel control for a gas turbine engine was compared with several state-space derived fuel controls. A single-spool, simple cycle gas turbine engine was modeled using ACSL (high level simulation language based on FORTRAN). The model included an analog fuel control representative of existing commercial fuel controls. The ACSL model was stripped of nonessential states to produce an eight-state linear state-space model of the engine. The A, B, and C matrices, derived from rated operating conditions, were used to obtain feedback control gains by the following methods: (1) state feedback; (2) LQR theory; (3) Bellman method; and (4) polygonal search. An off-load transient followed by an on-load transient was run for each of these fuel controls. The transient curves obtained were used to compare the state-space fuel controls with the analog fuel control. The state-space fuel controls did better than the analog control.

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