| VFTO is becoming the bottleneck problem,which prevents the development of China EHV/UHV power grid due to its widely and severe damage.Complex structure,high cost and difficult to engineering application are the main defects of the existing VFTO suppression methods.In view of this situation,a new method of suppressing VFTO by using the inductance of bus conductor is proposed,which is a spiral tube damping busbar.It is made of the conventional bus by hollowing out the inductance coil of the spiral tube and the resistance in parallel.In this paper,550 kV spiral tube damping busbar designed,and the key problems of its engineering application-dynamic and thermal stability,current capacity and insulation characteristics are analyzed.Finally,the suppression effect of the prototype is tested and verified.The specific work is as follows:(1)The mechanism of VFTO suppression by spiral tube damping busbar is studied,and the prototype is designed preliminarily.Based on transmission line theory,a distributed circuit model of spiral tube damping busbar is established,and the mechanism of VFTO suppression is simulated and analyzed.On this basis,a 550 kV spiral tube damping busbar prototype is designed.(2)The flow capacity and dynamic and thermal stability of the spiral tube damping busbar prototype are analyzed.The eddy current-temperature coupled field model considering eddy current effect and heat transfer of conduction,convection and radiation is established to calculate eddy current loss and temperature rise of damping busbar under rated current and short-term current,and the magnetic field,electromagnetic force,stress and deformation of damping busbar with helical tube are calculated under rated peak current.(3)The insulation characteristics of spiral tube damping busbar prototype under steady power frequency and transient impact(VFTO)are discussed.The criterion of insulation characteristic of spiral tube damping busbar prototype is proposed.Based on this criterion,the insulation condition of GIS under power frequency and VFTO impact is calculated.The influence of three factors,the size,location of metal particles and the convexity of irregular processing,on the insulation characteristics is discussed.(4)Verification test of VFTO suppression for spiral tube damping busbar was carried out.The test scheme of VFTO suppression is designed,including the generation and measurement of VFTO,installation of spiral tube damping busbar,etc.Statistical description method was used to analyze the inhibition effect.Based on the above research,the main conclusions of this paper are as follows:(1)Simulations and field tests verify that the damping busbar has a significant effect on VFTO suppression.The amplitude decreases by more than 30%,and the steepness and breakdown times decrease obviously.(2)The flow capacity and dynamic stability of spiral tube damping busbar meet the requirements.The temperature rise of theit is less than 75 K at rated current and 520? at short current,which verifies current-carrying capacity of the it meets requirements.When the damping busbar material is aluminum or copper,the stress and deformation meet the corresponding requirements,and the dynamic stability of copper is better.(3)Damping busbar has good insulation characteristics under power frequency.In addition,according to the insulation calculation and analysis under VFTO condition and influence factors,the requirements of surface cleanliness,smoothness and less burr are put forward for its processing and installation.The innovations of this paper are summarized as follows:(1)A new method to suppress VFTO using inductance of bus conductor in GIS is proposed.It not only breaks through the bottleneck of saturation under high current of magnetic ring method,but also has the characteristics of low cost,no need to change the structure of existing GIS equipment,convenient installation,and can meet the requirements of Engineering application.(2)Based on transmission line theory,a 14-level distributed parameter model of damping busbar is established,and the principle of VFTO suppression is analyzed.(3)The multi-physical field coupling model considering eddy current effect and heat transfer factors is established to analyze the flow capacity and dynamic and thermal stability of the damping busbar.The internal insulation criterion is proposed and the insulation characteristics under high frequency transient impact are analyzed. |
PDF Full Text Request