Optimization Design Of Dry Type Air Core Reactor Based On Thermal And Electromagnetic Combination Method

Inductance and current carrying ability are the important performance parameters of the reactor,due to the dry type air core reactor has the advantage of simple structure,good linearity and light weight,so it becomes the first choice for large power reactor among the half iron/iron core reactor and air core reactor.In this paper,taking the multi-encapsulation dry type air core reactor as research object,the theoretical research is carried out from the two aspects of electromagnetic and thermal optimization,to realize the metal conductor usage minumum of reactor,the constraint conditions are that the inductance and current carrying ability need to meet reactor's performance parameter requirements.In chapter 2,the fluid field-temperature field coupled simulation model is established based on the prototype parameters of reactor,and the temperature rise test results verify that the FEM(finite element method)calculates the temperature rise of the reactor with enough accuracy.Meanwhile,the rain cover is equivalent to the tilting baffle model,the temperature field,fluid field and heat flux of encapsulatuon surface are obtained based on the simulation results both with and without the rain cover,which provides a theoretical basis and precondition for the temperature rise computation and heat load optimization in subsequent.In chapter 3,according to the initial design parameters of reactor based on equal height and heat flux heat load distribution method,the encapsulation–air ducts unit is selected to reflect the overall temperature rise distribution of reactor.The effect of the change of air ducts width on heat dissipation efficiency is analyzed both forced and natural cooling conditions,and the heat dissipation efficiency can be further optimized possibility with different initial parameters are also achieved.At the same time,the above optimization theory is applied to the dry type iron core reactor,the practicability is verified by the design example.The essence both the air core reactor with multiple coaxial encapsulations and thick wall coils are same from the aspect of electromagnetic efficiency realization,thus,the actual air core reactor can be equivalent to a single thick wall coil with the same proportion,and the influence about the change of air ducts width and encapsulation number on the overall electromagnetic efficiency are studied.According to the heat dissipation efficiency and electromagnetic efficiency optimization theory mentioned above,the equation constraint conditions for the maximum temperature rise and inductance conservation are obtained considering the change of air ducts width and encapsulation number,combined with the tructure function of reactor,the thermal and electromagnetic combined optimization design method is achieved,and it can significantly reduce the usage of metal conductor,the design example and temperature field simulation results verify the validity of the optimization theory and methods.Currently,the rain cover is often added on the top of the reactor to reduce the impacts of environment factor.In chapter 4,the influences of different structure parameters of rain cover on the temperature rise of reactor are analyzed by the FEM,the contribution rate of rain cover to the temperature rise of the reactor and the optimum rain cover parameters are obtained.Meanwhile,according to the distribution characteristics of temperature field,fluid field and heat flux of encapsulatuon surface both with and without rain cover,the temperature rise calculation method and inner encapsulation heat load optimization method are proposed,it can be found that the temperature rise of the inner encapsulations are basic same,and the correctness is validated by the simulation results.According to the design parameters of the reactor based on the equal height and heat flux design method,the temperature rise of innermost and outermost encapsulations are lower due to the better dissipation conditions,the current carrying ability of encapsulation coils are not fully utilized.In this paper,the heat load distribution method is proposed both with and without the rain cover based on the temperature rise and encapsulatuon surface heat flux distribution characteristics,it can be realized that the temperature rise of innermost and outermost encapsulations are equal to inner encapsulations,the temperature field simulation results proved the practicability of the optimization method.In order to validate the proposed optimization theory and method are valuable in the design of reactor,in chapter 5,the parameters about one-armed inductance,insulation,temperature rise,coupling coefficient and dynamic thermal stability of high coupling split reactor are obtained according to the requirements of parallel circuit breakers,the coupling structure of reactor is proposed.At the same time,the encapsulation–air ducts unit heat dissipation efficiency,electromagnetic efficiency and encapsulation heat load optimization method are adopted in the design of high coupling split reactor based on the equal height and heat flux design parameters of the reactor,the electromagnetic field and temperature field simulation results verified the practicability of the aboved optimization theory and methods.