Research Of Design And Magnetic Field Of UHV Magnetic Saturable Controlled Reactor

In order to solve the problem of uneven distribution of primary energy and electricity load and further improvement of transmission capacity of power system lines,the UHV(Ultra High Voltage)transmission technology has been taken for existing voltage levels(500kV and 800kV).In reducing the line loss,increase transmission capacity and transmission distance,short circuit current suppression has made some achievements.However,some problems have been brought in the UHV transmission system,such as the difficulty of adjustment and control of voltage due to the increase of capacitive reactive power and the drastic changes in power system load flow.Therefore,a UHV magnetic saturation controllable reactor was developed in this thesis,which can effectively smooth regulate the reactive power of power system,suppress the operating frequency overvoltage,reduce the line loss,and provide a good operating environment for the UHV transmission system.A series of problems such as main/leakage magnetic field,operating point,loss and temperature rise are involved in the process of developing UHV magnetic saturation controllable reactor.At present,there is a lack of relevant design schemes and operation experience in the whole world,therefore,the following research work will be carried out on UHV magnetic saturation controllable reactor:(1)The structure and design dimension of the magnetic saturation controlled reactor are determined by the capacity of the reactor.In order to solve the problem that the operating point can't be accurately judged due to the affection of DC excitation on the reactance of the magnetic saturation controlled reactor,the reactor in the no-load state,the half limit saturation state,and the limit saturation state are analytical analyzed firstly in this thesis.A new method of calculating reactance values is proposed,the unsaturated core leg of magnetic saturation controllable reactor is equivalent to a double winding air reactor under the condition of half-saturation,and then the impedance voltage of the saturated core is calculated using the image method.The 10 kV magnetic saturation controllable reactor is manufactured,and the excitation characteristics and network side current harmonic content under different excitation conditions are analyzed.The correctness of the proposed program is verified.(2)The problems of the leakage magnetic field and the loss,the temperature due to the leakage magnetic field of the magnetic saturation controlled reactor can't be ignored.A method of leakage magnetic field suppression is proposed under the combined effect of circuit-magnetic,and a magnetic shunt structure is proposed to prevent local overheating of the UHV magnetic saturation controllable reactor.Specifically,the frame-type body magnetic shielding structure and the oil tank electric shielding are adopted,and the compensation winding are delta connected to provide the circuit for the third harmonic.The effect of leakage magnetic field and harmonics on the reactor is effectively reduced by the proposed measures.The leakage magnetic field and temperature distribution of UHV magnetic saturation controllable reactor under different control currents are presented.(3)In the calculation of the structural temperature rise,in order to solve the problems of traditional calculation method that it is complex and too much dependence on the empirical formula,a calculation method of loss and temperature rise of UHV magnetic saturation controllable reactor is proposed considering the flux density,percentage of short-circuit impedance,tank circumference and winding height.The specific simulation process and results are present.(4)In order to save the calculation time of the control characteristics,an analytical method for calculating the working current in different operation states is proposed.The calculation amount is greatly reduced compared with the finite element method.(5)The 500 kV,800kV and the first three-phase UHV magnetic saturation controllable reactor in the world are designed and manufactured.The magnetic field characteristics,control characteristics and dynamic characteristics are studied.The distribution of magnetic field characteristics and control characteristics under different excitation conditions are present.The research shows that the UHV magnetic saturation controllable reactor designed in this thesis has reached the standard of operation in network.The research has made up for the shortcomings of UHV magnetic saturation controllable reactor in our country and provided reliable equipment for the research of smart power grid.