Variable-speed multi-stage compressor and control method thereof

Abstract

The invention provides a variable-speed multi-stage compressor and a control method thereof. The control method comprises the following steps. A plurality of pieces of surge safety margin line information of a first-stage impeller and a second-stage impeller of the compressor are pre-stored in a controller; the controller controls the compressor to operate through the variable-frequency driver; and the controller calculates the working points of the first-stage impeller and the second-stage impeller and the distances between the working points and the corresponding surge safety margin lines according to the flow parameters and the pressure parameters of the first-stage impeller and the second-stage impeller. When it is detected that the distance between any working point in the first-stage impeller and the second-stage impeller and the corresponding surge safety margin line is smaller than or equal to zero, the controller preferentially adjusts the first-stage impeller or the second-stage impeller so that the working point can be away from the corresponding surge safety margin line. Therefore, the anti-surge control efficiency and accuracy of the multi-stage compressor are improved.

Description

technical field [0001] The present invention relates to a compressor, and in particular to a multi-stage variable speed compressor and its control method. Background technique [0002] The surge phenomenon is a periodic airflow oscillation phenomenon that occurs when the flow rate of the compressor fluid decreases to a certain extent. When the surge phenomenon occurs, the compressor will vibrate, affecting the stability of the compressor operation. In severe cases, it may cause damage to the impeller, bearings or other components, resulting in irreversible damage to the compressor. [0003] However, it is difficult to judge which stage of the impeller of the multistage compressor is about to surge with the traditional anti-surge judging technology. In addition, although the general control method for fixed-frequency compressors is widely used, due to the complex changes in the performance data of variable-frequency compressors at all levels, if the control method for genera...

AI Technical Summary

Problems solved by technology

When the surge phenomenon occurs, the compressor will vibrate, which will affect the stability of the compressor operation. In severe cases, it may cause damage to the impeller, bearing or other components, resulting in irreversible damage to the compressor.

[0003] However, the traditional anti-surge judgment technology is difficult to judge which stage of the impeller of the multi-stage compressor is about to surge

In addition, although the general control method for fixed-frequency compressors is widely used, due to the complex changes in the performance data of variable-frequency compressors at all levels, if the control method for general fixed-frequency compressors is applied to variable-speed multi-stage compressors , the controller has to invest several times the calculation time and control cost, which is extremely low in practice

Moreover, the fixed-frequency compressor cannot reduce the speed when it is under low load, and can only reduce the fluid flow by the capacity adjustment mechanism, and the anti-surge regulation efficiency is poor

Images