The dissertation is aimed at developing methodological bases for automating the management of gas transmission systems using the methods of mathematical modeling and computerization.
The aim of the work is to develop mathematical models of methods and algorithms for solving problems of control of stationary and transient modes of gas flow in main gas pipelines (MGP), detection and identification of leaks, as well as elaboration of concept and methodological bases of gas transmission system (GTS) automation and determination of structure and functions. -technical control automation systems.
To achieve this goal in the dissertation solved a number of problems and obtained new scientific results.
Mathematical models have been developed to describe the structure of the GTS, which take into account changes in its configuration during operation and dimensional heterogeneity. Based on the equations of dynamics, nonlinear mathematical models of gas flow in MGP elements are developed taking into account their leaks and on this basis boundary value problems are formulated, which model technological processes of GTS operation control, leak detection and MGP integrity control. Using known computational methods, developed methods for solving formulated problems and fast algorithms for their implementation.
A mathematical model for the propagation of small perturbations of gas flow parameters in a pipeline has been developed, which describes wave processes caused by compressor instability, local depressurization, fluctuations in pressure, density and temperature. Quantitative studies have revealed a significant dependence of the parameters of wave processes on the flow regime in which the disturbance occurs, as well as the location of fluctuations along the pipeline.
Transition control models have been developed, using which any process of transition from one stationary mode to another is determined by a finite set of parameters. Quantitative studies of gas flow transients in the MGP section under different control models have been carried out. Integral parameters have been introduced that determine the efficiency of gas transportation during the transition mode according to various criteria. Quantitative estimates of the efficiency of MGP gas transportation during the transition regime are obtained, depending on the applied transition control models.
Mathematical models of local leakage from MGP have been developed, which determine the intensity of gas leakage through a small hole in the pipe wall depending on the pressure and temperature of the gas in the pipe near the depressurization site. Using the developed computational methods, quantitative studies of the parameters of gas flow transients that occur in the MGP during its local depressurization and quantitatively studied flow parameters that can be used to detect and identify leaks. On this basis, mathematical methods for detecting and identifying leaks from MGP based on the measurement of gas flow parameters at control points have been developed and their accuracy has been investigated using the method of computational experiment.
The concept of automation of control of GTS of Ukraine which is based on the theory of MES of systems and PERA model according to requirements of the international ANSI / ISA-95 standard is offered. The functions and structure of the software system for automation of GTS management, as well as the system of monitoring the integrity of the MGP in its composition are defined and the approach to its step-by-step implementation with the preservation of existing tools that meet modern requirements is proposed.
Introduced integrated parameters of gas flow allow to quantify the efficiency of the transition process by energy and time parameters. Using the developed fast algorithms for solving boundary value problems, it can be used to control the transient modes of operation of the MGP in order to achieve a given process duration or specified energy performance.
The proposed mathematical models of local leakage and gas dynamics in MGP with leakage, as well as the developed fast algorithms for solving boundary value problems form a theoretical and mathematical basis for the method of detecting and identifying parameters of leakage MGP using an approach based on modeling mass, momentum and real-time energy and flow measurement data at control points along the pipeline.
The introduction of the GTS control automation system, based on the theory of MES systems, the PERA model and the international standard ANSI / ISA-95, the structure and functions of which are proposed in the work, will preserve the existing automation tools. This will create the preconditions for the transition from a functional to a process management model.
