基于磁场方向角的干式空心电抗器匝间短路故障检测方法OA

[Objective]Dry-type air-core reactors(DARs)are prone to inter-turn short circuits during operation.Characterized by low detectability and limited real-time observability,such faults pose a serious threat to the safe and stable operation of power grids.Although widely adopted in engineering,detection methods based on magnetic flux density amplitude exhibit limitations.Specifically,they are insensitive to inter-turn short circuits in inner windings,and detection accuracy is significantly degraded by magnetic field interference from adjacent equipment when multiple DARs operate in parallel.To enhance fault identification capability and achieve early warning,a DAR inter-turn short circuit detection method based on the magnetic dield direction angle(MFDA)was proposed.[Methods]Based on finite element simulation technology,the surrounding magnetic field distribution of a single-phase DAR under normal operation and inter-turn short circuits at different locations was analyzed.By arranging multiple monitoring points around the DAR,magnetic flux density data were collected,and the variation patterns before and after the fault were analyzed.Based on the principle of magnetic field superposition,the temporal variation patterns of MFDA at each monitoring point near the faulty phase in a three-phase DAR were calculated and analyzed.By comparing the MFDA data of a single DAR with those of multiple parallel DARs,the interference level of adjacent normally operating DARs on fault detection was quantitatively evaluated,and the placement of monitoring points was optimized.[Results]Simulation results indicate that after an inter-turn short circuit occurs in a single-phase DAR,both the amplitude and direction of the surrounding magnetic flux density undergo significant changes.Compared with the amplitude-based detection method,MFDA exhibits higher response sensitivity to inter-turn short circuits and can accurately capture the changes in electromagnetic characteristics caused by faults.By analyzing the temporal variation of MFDA at each monitoring point before and after the fault and establishing a fault decision threshold,inter-turn short circuits in single-phase DARs can be diagnosed.For the scenario of three-phase DARs operating in parallel,arranging monitoring points near the faulty phase and on the symmetric perpendicular bisectors of the normal phases can effectively mitigate magnetic field interference from adjacent DARs.By combining the temporal characteristics of MFDA with the fault decision threshold,short-circuit faults can still be diagnosed.[Conclusions]The proposed MFDA-based detection method can effectively address the limitations of the magnetic flux density amplitude detection method in terms of sensitivity and anti-interference capability,providing a reliable technical approach for real-time monitoring of DAR operating status and fault early warning.Based on the simulation results,the proposed method shows strong potential for engineering applications and provides practical support for improving the operation and maintenance of power grid equipment and ensuring the safe and stable operation of power systems.