Research On The Technology Of Optical Current Sensing Stacked-up Structure To Resist External Magnetic Interference

Electronic sensors have a good application prospect in the future development of power grid due to their good transient performance and excellent insulation performance,and Magneto-Optical Current Sensor(MOCS)is a kind of electronic sensors with rapid development.Straight-through optical MOCS have high operating stability,but are susceptible to external magnetic interference.Therefore,this paper focuses on the basic theoretical issues of external magnetic field interference,studies the internal laws of external magnetic field interference and the corresponding antiexternal magnetic interference technology,and proposes feasible solutions to improve the anti-external magnetic interference capability of MOCS.Firstly,starting from the basic Ampere-loop law,by defining the concepts of discontinuous integral path,integral Angle and so on,the corresponding magnetic field integral expression is derived when the current is located inside or outside the discontinuous closed path.Furthermore,a mathematical model suitable for analyzing the external magnetic interference of MOCS arranged by symmetrical polygon is established.This mathematical model has no special requirements on the current location and the number of magneto-optical sensing units,which lays a theoretical foundation for solving the problem of external magnetic field interference in straightthrough optical MOCS.Secondly,based on the mathematical model of external magnetic field interference,the center deflection model of closed path is proposed.On the basis of this model,the optimum center deflection Angle is obtained.It has been proved by theory that there is always a unique optimal center deflection angle for the straightthrough MOCS with any number of magneto-optical sensing units arranged in symmetrical polygon mode,Based on this,a novel stacked-up MOCS structure is proposed.Both theory and simulation results show that this structure can basically resist the magnetic field interference caused by the current at any position outside the sensing structure.T hirdly,a general error evaluation model of anti-external magnetic interference technology is proposed-The factors influencing the effect of stacked-up MOCS against external magnetic interference are studied and corresponding improvement schemes are proposed.At the same time,the anti-interference ability of stacked-up MOCS and conventional MOCS is compar ed and analyzed.Theoretical calculation and simulation experim ents show that the measurement error of stacked MOCS can be completely ignored in the steady-state and transient conditions,and stacked-up MOCS have excell ent anti-external magnetic interference abilityFinally,a prototype of the stacked-up MOCS is developed and its performance is tested under various conditions.The test results show that the prototype meets the accuracy level of 0.2/5P and has excellent anti-external magnetic interference performance.This type of MOCS has no special requirements on the relative spatial position of the sensor and the interference current,which promotes the practical process of MOCS.