Study On Relay Protection In Associated Area Of HVDC Converter Station

After the 21 st century,the problem of resource and environment caused by the irrational energy consumption structure has become increasingly prominent.To solve the contradiction between China's economic development and environmental resource shortage,we should develop clean energy and renewable energy.The distribution of China's power resources and user areas is very unbalanced.It determines the necessity of “transmitting electricity from the west to the east”.Compared with traditional AC transmission,HVDC transmission technology has the advantages of low loss,large transmission capacity,and flexible control in long-distance transmission.It has been widely used in China.The input of large-scale HVDC transmission projects brings new features to the power grid.When faults occur in the areas associated with AC/DC systems,the interaction between AC and DC systems will lead to changes in fault characteristics.The traditional relay protection mainly depends on the local electric quantity information to form the protection criterion.Under the action of the AC/DC system,the protection performance will be affected.Therefore,to ensure the safe and stable operation of the power system,further research should be conducted on the relay protection in the associated area of HVDC converter station,and the reliability of it should be improved.As a result,the relay protection can be adopted to the new characteristics of AC-DC hybrid power transmission in the power system.This paper studies the HVDC converter station relay protection,and focuses on analyzing the configuration,basic principles and criterion of protection.It builds an HVDC power transmission model based on PSCAD/EMTDC power system simulation software and compiles the converter area protection program using Matlab simulation software.and studies the DC protection characters through simulation method?The system analyzes the operation of DC protection during faults in the region and out the region and analyzes the DC protection that is susceptible to AC system faults.In order to solve the problems existing in the relay protection in the associated area of the DC converter station,as for DC protection,the idea of constructing the protection system based on the layered protection shared information is proposed,and a protection scheme for improving the DC backup protection performance by using the wide area protection is proposed to solve the DC backup protection to solve problems related to AC protection.As for AC protection,a new AC line distance protection method based on the detection of HVDC station information is proposed.Test inverter commutation failure after a fault to solve the problem When the DC commutation fails,the distance protection performance of the AC system becomes worse,and the impact of the commutation failure on the distance protection is avoided,and the feasibility of the scheme is verified through simulation.