Research On CEEMDAN Based Single Pole Grounding Fault Detection Approach For MMC-HVDC Cable Lines

With the steady progress of China's "strong smart grid",HVDC Flexible System with MMC has been a great advantage in the process of electricity transmission.It is very necessary to ensure safe and reliable operation for MMC-HVDC.The effective detection method has a certain theoretical and engineering significance for the study of the protection of the monopole fault of the MMC-HVDC transmission system.This thesis proceeds from the MMC-HVDC transmission system with MMC converter as the main research object,analyzes the structure,operates principle and control strategy of MMC converter.This thesis explains the operation of MMC-HVDC transmission system on the basis of theory.MMC-HVDC simulation model is built on the PSCAD platform to configure the MMC converter's system level coroller,station level controller and valve level controller mainly from the structure and control strategy of the MMC converter.The monopole grounding fault detection method for MMC-HVDC system is proposed,based on CEEMDAN's time-frequency analysis characteristics of current transient signals,combins with the inherent mode energy entropy theory and the single ended traveling wave location theory.In the practical application of MMC-HVDC system model built in PSCAD,the method can accurately detect the fault area and give the detection criterion by analyzing the characteristics of the natural mode component and the energy entropy value after the unipole fault.This method can put forward the suitable detection criterion according to the different application system,and can effectively detect the effect of the monopole fault.