Research On Magnetic Field And Electromagnetic Force In UHVDC Dry-type Smoothing Reactor

Because of the deviation between the energy center and economic center in China,Ultra high-voltage direct current transmission technology is widely used.UHVDC Dry-type smoothing reactors,as one of the most important equipment in HVDC,can be utilized to smooth ripples,restrict short circuit current and prevention commutation failure.They have been widely used in practical engineering.However,the distribution of the electromagnetic field,the electromagnetic force and its’ influence on the insulating layer in the type reactor have not been discussed in any literatures.The dry-type smoothing reactor in Xiangjiaba-Shanghai ±800kV/4000 A UHVDC Project is taken as an example in this paper.In order to calculate the current distribution of each branch in reactor under different running state,different circuit model for different situation are established.The magnetic model of the object is established in the finite element analysis software ANSYS.And then,the distribution of magnetic field and magnetic force are calculated in detail.In order to study the stress of the reactor insulation layer under the electromagnetic force,the finite element structure model of the object is established in the finite element analysis software SOLIDWORKS SIMULATION,and the deformation and stress of each layer are obtained.Based on this,the mechanical strength of the reactor is verified and the weak link of the reactor is discussed.The improvement suggestions are given.The calculation results show that the problem of circulating current and current concentration is very serious in the transient process due to the lack of consideration about transient in the design stage.The reactor due to its structure,the magnetic induction intensity distribution tend to reduce from the inside out,so the current distribution should be gradually increased from the inside out.The overall mechanical strength of the encapsulated insulation layer is sufficient to withstand electromagnetic forces in various operating conditions,but excessive local electromagnetic forces may cause malfunctions such as dropping of the cooling-ducts and detachment of the coil insulation,etc.,so measures to improve the mechanical strength must be taken.