Patent ID: 8412357

Claim:
A system for controlling a cooling tower that cools condenser fluid for a condenser of a chiller, comprising: a cooling tower fan system that controllably varies a speed of at least one fan motor; an extremum seeking controller that receives inputs of power expended by the cooling tower fan system and of power expended by the chiller, wherein the extremum seeking controller provides an output to the cooling tower fan system that controls the speed of the at least one fan motor, wherein the extremum seeking controller determines the output by searching for a speed of the at least one fan motor that minimizes the sum of the power expended by the cooling tower fan system and the power expended by the chiller; a model-based controller for controlling the speed of the at least one fan motor; a processing circuit configured to store process characteristics associated with a steady-state of the extremum seeking controller; wherein the processing circuit is further configured to switch from using the extremum seeking controller to using the model-based controller to control the fan speed and wherein the processing circuit operates the model-based controller using the stored process characteristics.