ABSTRACT

Optimization system for local control of compressor station operation is described in this paper. The algorithm is planned to be one of the basic stones of the automatic control of compressor stations at the Czech gas transportation company TRANSGAS. The compressor station topography is arbitrary. The technology is modelled in full detail, each compressor unit is described by its individual characteristics. The optimization is performed as a steady-state optimization; the dynamics of the compressor station is fully determined by the dynamic behaviour of the surrounding network. The currently used criterion is represented by a total of the consumed energy or a total of the price for the consumed energy. The criterion can simply be modified to respect other goals. Currently, the configuration of compressors is assumed to be fixed. The function of the algorithm is demonstrated on the example of the compressor station with ten compressor units in operation. Finally, the planned future enhancements of the algorithm are outlined.

1 Introduction

This paper deals with the local optimization of compressor station operation. The solution of this task has two main ways of use: Firstly, on its basis the algorithm for local automatic (optimized) control of a compressor station can be built up. This is needed, since the network control very usually ends with the definition of the global set-points for the compressor stations and the consequent task is to determine the configuration of every compressor station and load of each running machine. Secondly, the solution of the optimized local control represents one step ahead towards the optimum control of the whole network. The developed solution is based on the simulation model. The model enables to describe in a very accurate and detailed way the general structure of the compressor station including its equipment. Our approach makes it possible to model and control a compressor station with an arbitrary number and interconnection of machines, coolers, valves, pipes, resistors, etc., including such configurations that contain several inputs and/or outputs. In this paper we will describe the system for the optimization of the compressor station operation for a user defined, i.e. fixed, configuration.

2 The Purpose of the System

In principle, the optimization problem can be divided into two main subproblems. The first covers the optimization within a fixed configuration of the compressor station. The second sub problem is the design of the configuration. This can further be divided into the design of configuration of a starting compressor station and the design of change of configuration of a running compressor station. The final solution of the optimization can be of two kinds: Off-line optimization, which can be computed on the basis of on-line data, but without straight feedback to the reality, and the on-line optimization, which operates also with differences between the model data and the measured ones. We have solved the off-line optimization, and we are currently working on the on-line optimization within a fixed configuration. Finally, we intend to solve also the automatic switching of configuration of a compressor station.

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