Surge control systems and methods for dynamic compressors

A controller for a dynamic compressor including a motor and a compression mechanism connected to the motor and operable to compress a working fluid upon operation of the motor, the controller comprising:

• a processor;
• and
• a memory, wherein the memory stores instructions that program the processor to:
• operate the motor to compress the working fluid at a motor speed greater than a predicted minimum surge speed plus a control margin;
• determine an average value of an operating parameter over a period of time;
• determine when surge events have occurred, wherein the surge events are determined to have occurred when the compressor is in surge, wherein the compressor is in surge when a difference between the determined average value of the operating parameter and a present value of the operating parameter exceeds a threshold operating parameter value;
• compare a speed of the motor when each surge event was determined to have occurred to a sum of the predicted minimum surge speed, the control margin, and a charge margin;
• determine whether or not to take a protective action when the processor determines that a surge event has occurred, wherein the protective action comprises generating an alert, wherein the processor determines to generate an alert when the speed of the motor when the surge event was determined to have occurred exceeds the sum of the predicted minimum surge speed, the control margin, and the charge margin;
• and
• increase the control margin when the processor determines to generate an alert.

A method of controlling a dynamic compressor including a motor and a compression mechanism connected to the motor and operable to compress a working fluid upon operation of the motor, the method comprising:

• operating the motor to compress the working fluid at a motor speed greater than a predicted minimum surge speed plus a control margin;
• determining a surge threshold current value;
• determining, by a processor, when surge events have occurred, wherein the surge events are determined to have occurred when a difference between an average current value of the motor over a period of time and a present current value of the motor exceeds the surge threshold current value;
• storing an indication of each surge event that the processor determined to have occurred;
• comparing a speed of the motor when each surge event was determined to have occurred to a sum of the predicted minimum surge speed, the control margin, and a charge margin;
• determining whether or not to take a protective action when the processor determines that a surge event has occurred, wherein the protective action comprises one of generating an alert, wherein determining whether or not to take a protective action comprises determining to generate a charge alert when the speed of the motor when the surge event was determined to have occurred exceeds the sum of the predicted minimum surge speed, the control margin, and the charge margin;
• and
• increasing the control margin when it is determined to generate an alert.