The Research On Thermal Field Calculation Of Tightly-coupled Dry-type Air-core Split Reactor

The tightly-coupled dry-type air-core split reactor is the key equipment in parallel circuit breaker system, and used for two-slip current sharing and current limiting. The maximum temperature rise in the encapsulation of tightly-coupled dry-type air-core split reactor is an important technical indicator to measure its thermal stability. The research on temperature distribution law of dry-type air-core split reactor under its working condition helps to optimize reactor design and improves the quality of the reactor, so as to improve the security and stability of the whole power system.In this thesis, the physical structure of tightly-coupled dry-type air-core split reactor as well as its current sharing and current limiting operation mechanism is introduced, the inductance of tightly-coupled dry-type air-core split reactor when working under current limiting and current distribution condition is calculated respectively, the relationship between constructual parameters of encapsulation and inductance of reactor under current limiting condition is analyzed, the effect of number change of turns on current distribution of the encapsulations is also analyzed, so as to guide and optimize the thermal field design of the tightly-coupled dry-type air-core split reactor.The steady thermal field of reactor when working under natural convection and forced convection are simulated using finite element simulation software, and calculated using finite difference method respectively. The results of the two approaches are consistently the same: the maximum steady temperature rise of column-type air-core reactor happens approximately 10% to its top; In the 1/3 part of the reactor to its bottom, the temperature will rise rapidly to the increasing of height, yet the gradient rate is gradually decreasing; In the 10% part of the reactor to its top, the temperature will drop rapidly to the increasing of height; In the part between, the temperature will rise slowly to the increasing of height.Besides, The transient thermal field of column-type air-core reactor when working under forced convection is simulated using finite element simulation software, and calculated using finite difference method respectively. The result shows that: the transient thermal field of column-type air-core reactor's encapsulation is mainly decided by the heat generation rates of each encapsulation, yet has little correlation with the wind velocity in airway of the both sides; The transient thermal field distribution law in every encapsulation of the reactor are the same, that is, the transient temperature rise from the bottom to the top of the encapsulation are the same; The maximum transient temperature rise of column-type air-core reactor rises linearly with the increasing of hearing time.In the last, the flow field distribution of dry-type air-core reactor when working under forced convection with different structure of air ducts and rain shelters are calculated respectively and then compared together. The overall thermal structure of the dry-type air-core reactor when working under forced convection is designed according to the final result.