Method for controlling viscosity of lubricating oil of centrifugal compressor

The invention provides a control method for lubricating oil viscosity of a centrifugal compressor. The control method comprises the following steps executed during the working period of the centrifugal compressor: (1) obtaining the real-time solubility D1 of a refrigerant in an oil tank (102) in lubricating oil, wherein the oil tank (102) is in fluid communication with the centrifugal compressor (101); and (2) comparing the real-time solubility D1 with a target solubility threshold D. If the comparison result is that the real-time solubility D1 is larger than or equal to the target solubility threshold value D, the operation of reducing the real-time solubility D1 is executed till the real-time solubility D1 is smaller than the target solubility threshold value D. And if the comparison result shows that the real-time solubility D1 is less than the target solubility threshold value D, performing an operation of controlling the viscosity of the lubricating oil in real time based on the real-time solubility D1.