Combined control of fans of gas cooling units electric drives

Abstract

The problem of the temperature control at the outlet of gas cooling units of compressor stations of main gas pipelines is discussed. To solve the problemt, a discrete or frequency control of electric motors of fans of gas air cooling devices is used. The problems of electromagnetic compatibility that arise in typical power supply systems of gas cooling installations when connecting electric motors of fans through frequency converters are noted. A combined fan motor control system is considered, in which the electric motors are divided into two groups. The electric motors of the first group are connected to the network directly, the second through frequency converters. By reducing the number of electric motors connected to the network through frequency converters, the negative impact of frequency-controlled drives on the quality of electricity is reduced and the costs of modernization projects are reduced in comparison with the option of the variant using a frequency converter for each electric motor. The energy characteristics of the combined control system are analyzed. The relations that establish the relationship between the temperature difference at the cooling unit and the power of the fan motors for various control methods are obtained. The optimal control algorithm according to the criterion of maximum power saving is proposed, which provides for the interconnected control of the number of discrete-controlled motors and the speed of frequency-controlled drives. The variants of the implementation of the optimal control algorithm are discussed. Analytical expressions for power saving on the fan motor shaft in a combined system compared with a discrete one and a method for estimating energy savings are considered. The obtained results are recommended to be used to assess the technical and economic efficiency of projects for the modernization of electrical complexes of gas cooling units.