Research Of Magnetic Bias Fault Monitoring And Alarm System Based On Transformer High Voltage Incoming Line

With the construction of the UHV lines of the State Grid,the DC bias of transformers caused by the grounding pole current of 1800kV UHVDC converter stations has attracted widespread attention.There have been many studies on the monitoring of transformer bias in the vicinity of the grounding pole site.However,insufficient attention has been paid to the risk of transformer bias accidents caused by the geomagnetic induced current(GIC)generated by the geomagnetic storm.When a strong magnetic storm invades the power grid system,it will often cause the system circuit to trip within a few minutes or even tens of seconds,and in severe cases,it will cause equipment damage and blackouts.Therefore,it is of great significance to on-line monitoring of DC bias current.At present,most of the DC bias monitoring is installed at the neutral point of the transformer,but the installation of the monitoring device at the neutral point of the transformer has problems such as insufficient awareness of geomagnetic storms,large investment,and relatively large amount of construction.Moreover,installing the device at the high-voltage incoming line can still monitor GIC changes in real time,and meet the withstand voltage requirements of the monitoring equipment.Therefore,this paper designs the magnetic bias monitoring and alarm system based on transformer high-voltage incoming lines.This article first analyzes the feasibility of the current transformer as the power supply of the monitoring device,and then simulates the electromagnetic environment around the monitoring device.Then set the GIC warning indicators,and completed the structural design of the monitoring system accordingly.Finally,the DC biasing APP was developed on the Android side to fulfill the functional requirements.The specific work and research content are as follows:(1)The current transformer power circuit is designed,and the circuit module is verified by Matlab simulation.(2)The calculation model of the monitoring device through the wire is established,the electric field environment in the monitoring device under different conditions is simulated through CST software,and the installation method of the device is designed according to the results.(3)According to the accident data caused by the geomagnetic storm,the GIC warning index is set,and the operation logic of the warning system is described in detail,and the monitoring system structure is designed on this premise.(4)First analyze the functions required by the mobile APP,complete the APP interface design and interface interaction through programming design,then design the SQL data hierarchy model,program according to the model,complete the connection between the APP and the database,and finally through the APP page Show and verify the software development of the mobile phone platform.