Research On Intelligent Motor Protection System Based On DSP

In practical engineering applications,the poor working conditions and the lack of routine maintenance often lead to the motor failure or even permanent damage,which have a great impact on industrial production and people's lifes.It is necessary to realize real-time monitoring,fault judgment and protection in order to ensure the safe and reliable operation of the motor.The research status of motor protection technology was introduced at first.Then a intelligent protection device combining with the characteristic of the ship power system,which is suitable for low-voltage motor,was designed,the main works are listed as follows:First of all,the motor protection principle and characteristics of different motor fault types were analyzed,and fault identification methods and protection setting logics were also proposed in the thesis.At the same time,At the same time,the sampling and protection algorithms were introduced as follow.Secondly,two real-time frequency tracking method,such as the hardware scheme based on zero-crossing frequency detection and the software scheme based on phase-locked loop frequency tracking,were discussed.Both sides of advantages and disadvantages were compared too.Decoupled double synchronous reference frame PLL was adopted to track the power system frequency.The relevant simulation and experiment were completed in the following parts.Thirdly,according to the requirements of motor protection device for measurement,caculation and protection,the dual-processor architecture with DSP+ARM was adopted.Both the data acquisition and the event management were completed by DSP and ARM respectively.Modular idea was used to design the software and hardware of the protection device.In addition,the HMI of motor protection device was designed in this thesis to realize protection parameters setting and the real-time monitoring of motor operating conditions.Finally,the frequency tracking based on the software phase-locked loop was verified on the experimental platform.The parameter correction of the sampling channels and the verification of fault protection logic of the protection device were completed by using the relay protection tester.In addition,a variety of peripheral circuits of the motor starting mode were designed.The experiments,such as starting and stopping operation of the motor and various kinds of motor fault protection,were finished successfully.