Design Of The Monitoring Device On Capacitance Current And Simulation Research On Resonant Grounding System

In China, the neutral none grounding mode is adopted in the 6~35kV distribution networks. In recent years, the grounding capacitance of lines is increased with the reconstruction of city networks. When single-phase grounded capacitive current exceeds the limited value, the arc is difficult to extinguish. In order to avoid enlarging the fault, resonant grounding mode should be adopted.The basic principle of resonant grounding system, characteristics of all kinds of automatic tracing and compensation devices of arc-suppression and various kinds of indirect measuring methods on network earth capacitance was deep analyzed and studied in this thesis. On the basis of this, injecting frequency conversion signal method on measuring capacitive current is selected to use here. It is reliable and its error is small, timeliness is good.The accurate track and the precise measuring on capacitive current are premises of which the arc-suppression can precisely compensate. Therefore, the on-line monitoring device on capacitance current based on dual SCM (single chip microprocessor) is realized .The software and hardware design scheme of the device is given in this thesis. The host computer's software and hardware debugging and the serial communication between the host computer and the subordinate computer are achieved; at the same time the software and hardware design of the subordinate computer is completed. The hardware architecture of the device is compact and reasonable. The software based on the C51 language is easy to be maintained, which development efficiency is high and transplant ability is strength.Moreover,a design on a new arc-suppression with magnetic bias model, a zigzag grounding transformer model design and an excitation control system model design is realized with the PSCAD/ EMTDC simulation software based on analysis and studies to principles of the arc-suppression with magnetic bias. At the same time, the simulation research to each kind of running status of the resonant grounding system has been carried out. The simulation test result has indicated that the simulation model is reasonable, effective and compensating networks quickly and effectively compensate capacitive current with the arc-suppression with magnetic bias, which is able to quickly extinguish the arc.