Teaching experimental design of flexible DC system protection based on RTDS
[Objective]Due to the high proportion of new energy and power electronics in the new power system,as well as new forms of power grids,traditional electrical experimental teaching is facing significant challenges.Traditional teaching laboratories lack a new power system experimental platform,and the experimental teaching mode is outdated,making it very difficult to simulate the various forms and different penetration rates of new energy nodes.[Methods]A new power system teaching experiment based on a real-time digital simulator(RTDS)was designed to address the aforementioned problems by constructing a new power system model and a closed-loop experimental scenario.In addition,a self-developed DC protection prototype is used to design a flexible DC system protection teaching experiment.First,a Peterson equivalent circuit is applied to analyze the fault characteristic at both ends of the flexible DC line.It can be found that when an internal pole-to-pole fault occurs,the polarity of the line-mode fault current component(LFCC)at both ends of the line is the same.When an external pole-to-pole fault occurs,the polarity of the LFCC at both ends of the line is opposite.Then,the pilot protection based on the LFCC for the flexible DC grid is constructed,and the DC protection prototype is developed.Second,the flexible DC system protection experiment based on the RTDS is designed.Students can build the flexible DC system model in the RTDS software and connect the DC protection prototype to the closed-loop testing platform.Then,the DC protection experiment can be conducted by setting internal and external faults in the flexible DC system.To provide students with a more intuitive understanding of the differences between the RTDS and ordinary simulation software,PSCAD is added as a skill enhancement component to motivate the research enthusiasm and innovation ability in students.In addition,safety training and operation training are added to the experiment,and the experimental teaching is carried out by the equipment administrator teacher to reduce the equipment fault rate.By using the group experiment,the problems of small quantities of large equipment and the conflicts between scientific research and teaching experiments can be solved.[Results]The experimental test results indicate that when an internal fault occurs,the polarity of the LFCC at both ends of the line is the same,and the tripping signals of the two prototypes change.The protection action times are 2.32 and 2.65 ms,respectively,which meet the protection speed requirement.When an external fault occurs,the polarity of the LFCC at both ends of the DC line is opposite,and the tripping signals of the two protection prototypes do not change.The reporting items of the two prototypes also indicate that the fault is external.Meanwhile,simulations of the flexible DC system in PSCAD show that the sampling rate affects the waveform accuracy and simulation time.[Conclusions]Therefore,the experimental design not only helps students understand the theoretical knowledge of the new power system and cultivate their innovation,practical hands-on,and scientific research capabilities but also effectively improves the utilization rate of large equipment.In future work,more experimental teaching projects based on large-scale equipment will be developed for multiple courses to cultivate student creativity and meet the needs of talent cultivation in the new era.
new power systemlarge-scale equipmentteaching experimentDC prototype
万方数据
维普
