Multi-shaft compressor unit system with multiple compressors running in series and control method of multi-shaft compressor unit system

The invention provides a multi-shaft compressor unit system with multiple compressors running in series and a control method of the multi-shaft compressor unit system. The problems that compressors of an existing compressor unit in series are low in running efficiency and complex in configuration are mainly solved. The system comprises a low-pressure unit, a high-pressure unit, a first output pipeline, a second output pipeline, a high-pressure anti-surge valve, a low-pressure anti-surge valve, an emptying valve and an emptying silencer; the low-pressure unit and the high-pressure unit are multi-section multi-shaft centrifugal compressor units; the low-pressure unit is driven by a power frequency motor, an inlet of the low-pressure unit communicates with external atmosphere, and an outlet is respectively connected with an inlet of the high-pressure unit and the first output pipeline; the high-pressure unit is driven by a variable-frequency motor, and an outlet of the high-pressure unit is connected with the se