The monitoring system consists of signal acquisition and controller, whose main task is to extract information from the system and control the power output of SMES according to the needs of the system. The signal acquisition part detects various technical parameters of power systems and SMES, and provides basic electrical data to the controller for power system status analysis. The controller calculates the power demand according to the state of the power system, and then adjusts the voltage at both ends of the magnet through the converter to charge and discharge the magnet. The performance of the controller must match the dynamic process of the system in order to effectively achieve the control purpose. The control of SMES is divided into inner loop control and outer loop control. As the primary controller, the outer loop controller is used to provide active and reactive power reference values required by the inner loop controller, which is determined by the characteristics of SMES and system requirements. The inner loop controller generates the trigger signal of the converter switch according to the reference value of the outer loop controller child.