The Controllable Shunt Compensation And Secondary Arc Suppression For Large Capacity Long Transmission Line

For the requirement of long-distance and large transmission capacity,ultra-high voltage(UHV) transmission technology becomes more and more significant.The research and application of extra/ultra-high voltage reactive power compensation device based on controllable reactor are the great key topic of current power system in our country.According to the characteristics of the large capacity long transmission line,the shunt compensation scheme by adopting controllable reactor is introduced in this paper. And the structure,characteristics and loss of the controllable are analyzed completely. Then the capacity adjustment for the compensation of large capacity long transmission line is studied.Meanwhile,the suppression of secondary arc is also achieved through the coordinate control between shunt reactors and the neutral small reactor.The thyristor turn-off angle is introduced in this paper for improving the state variables based mathematic model of controllable reactor,which describes the different operation modes of controllable reactor accurately.Furthermore,simulation model is established in MATLAB,and the harmonic characteristics are studied deeply.According to the phase-shifting harmonic compensation theory,a circuit topology of controllable reactor harmonic suppression is put forward,which can effectively reduce the harmonics injected to the system by controllable reactor itself.Quantitative calculations which have guiding significance in engineering are gained.Furthermore,the Electromagnetic field analytical model and field-circuit coupled model of controllable reactor are established in ANSYS.The magnetic circuit system and loss are analyzed through finite element analysis method.All these provide basic theory for the optimization design of large capacity and high voltage controllable reactor.The correlation analysis technology is introduced,and the phase similar degree function,frequency similar degree function and waveform similar degree function are established for the first time.Thus,the relationship between voltage and current is described from a different point of view,from which the definition of reactive power is derived and a new detection method of reactive power is proposed.The closed-loop system of power control for the controllable is built to achieve the reactive power compensation of the large capacity long transmission ling,which can effectively control the compensation capacity of the controllable reactor and keep the system voltage within the scope of permit. For the difficult extinguish of secondary arc in ultra-high voltage system,the controllable shunt reactors with small neutral reactor is used widely to suppress such phenomenon.The dynamic model of secondary arc based on distributed parameter on UHV long line is established.Quantitative analysis of variation characteristics of the secondary arc current under different influence is studied.The coordinative control relationship between shunt reactor and the neutral reactor under different compensation degree is gained,which provide reference for project application.A group of experimental device of controllable reactor is designed,and theoretical analysis results are verified via the corresponding experiments.