Sensing head of all-fiber current transformer

Abstract

The invention discloses a sensing head of an all-fiber current transformer. Grooves are respectively formed in an upper cover of the sensing head and a lower cover of the sensing head; a sensing optical fiber, an all-fiber one-fourth wave plate and an optical fiber end surface reflecting mirror form an optical fiber sensing part of the all-fiber current transformer by a welding mode; the optical fiber sensing part is uniformly wound on a sensing framework in a spiral manner; the sensing framework wound with the optical fiber sensing part is placed in the groove of the lower cover of the sensing head and integrally packages the upper cover of the sensing head with the lower cover of the sensing head; a lead head which is internally provided with a lead hole is processed in the upper cover of the sensing head; and a polarization-preserving optical fiber is used as a lead-out end of the sensing head of the all-fiber current transformer, is partially connected with the optical fiber sensing part and is led out of the lead hole. According to the sensing head disclosed by the invention, various negative influences such as linear birefringence, Verdet constant temperature effect and one-fourth wave plate phase delay temperature effect of the optical fiber sensing part can be effectively eliminated.

Description

technical field [0001] The invention relates to the field of sensors, in particular to a sensor head of an all-fiber current transformer. Background technique [0002] In the "Twelfth Five-Year Plan" of the State Grid, the construction and transformation of digital substations will be fully rolled out, and UHV, as the backbone of my country's strong smart grid, will also enter the peak period of construction. With the development of the power grid, the traditional electromagnetic current transformers widely used at present have exposed their fatal flaws, such as extremely difficult insulation at high voltage levels, analog output, magnetic saturation, etc., which cannot meet the new requirements of the power grid development strategy. Urgently need to develop a new type of current measuring device! At home and abroad, they finally focus on digital electronic current transformers, among which all-fiber current transformers are the most advanced type, representing the current...

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Problems solved by technology

[0006] The patent "Preparation Method of Sensitive Coil of Reflective Optical Fiber Current Sensor" (application number 200810226743.5) and the patent "A Sensitive Ring of All-Fiber Electronic Current Transformer" (application number 200910237041.1) disclose a sensitive coil The preparation method, the sensitive coil prepared by this method has great reference significance for the preparation of the current transformer sensitive ring, but there are also certain defects: the groove processed on the skeleton is in the shape of an Archimedes spiral, and the sensing fiber Placed in the groove, it is impossible to increase the circular birefringence to reduce the negative impact of linear birefringence; once the groove on the skeleton is processed, its shape and length cannot be adjusted, and the length of the sensing fiber placed in the groove varies with the It is fixed and cannot be adjusted in real time during the actual assembly process; the ring skeleton of the winding optical fiber sensing part is processed by metal materials, which is not only heavy, but also the linear expansion coefficient of the metal material is inconsistent with that of the optical fiber. Under the condition, the sensing fiber wound on the skeleton will be subjected to stress (if the linear expansion coefficient of the skeleton is greater than that of the fiber, it will produce an outward extrusion stress on the sensing fiber wound on the skeleton, otherwise, if the skeleton The linear expansion coefficient of the optical fiber is smaller than that of the optical fiber, which will make the optical fiber detached from the skeleton to a certain extent and be in a suspended state, which will also generate stress), which will intensify the negative effect of the linear birefringence of the sensing optical fiber; fixing the optical fiber with glue will cause the optical fiber to be stressed. Affect the measurement stability of the sensor head in a variable temperature environment

[0007] The patent "An All-fiber Sensor Head for Optical Fiber Current Sensor" (Application No. 200810056485.0) discloses a preparation method of the sensor head, which has the advantage of being convenient for on-site installation and disassembly, but also has certain defects: the structure is comparatively It is complex and uses a large number of parts, which brings great difficulty to the processing; the sensing optical fiber is wound on the glass skeleton and the hose, and the linear expansion coefficient of the hose is quite different from that of the optical fiber. , the sensing fiber wound on it will be subject to greater stress, which will intensify the negative effect of the linear birefringence of the sensing fiber

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