Dry Air Core Reactor Design Based On AC/DC Mixing

With the rapid development of direct current transmission in China,the demand for reactors in direct current transmission in China is also increasing day by day.But the traditional design method of dry-type air-core reactors is generally designed only for ideal DC reactors or AC reactors.Because there are smooth-wave reactors,bridge-arm reactors,DC filter reactors,and PLC(Power Line Carrier)reactor in DC transmission projects.This type of reactor operates under AC and DC mixed currents.However,it is difficult to meet the performance requirements of various aspects of reactors by designing such reactors by traditional methods.Therefore,it is of great significance to develop analysis and design of AC-DC hybrid reactors.Firstly,in this text,the operation characteristics and design difficulties of the AC/DC hybrid reactors are analyzed in detail,and the design method of the AC/DC hybrid reactors is preliminarily determined according to the design specifications of the HVDC dry-type air-core reactors.According to the structural characteristics of the air-core reactor,using the principle of electromagnetism,the coaxial and non-coaxial inductance calculation formulas based on the Bartky transformation method are deduced,and the equivalent voltage equation of the air-core reactor based on the mutual inductance coefficient is introduced in detail.In this text,the specific design content of the isothermal rise method for calculating the structural parameters of the dry type air-core reactor is presented,and the calculation formulas for the number of turns,the current,the wire gauge and the number of parallel connections of the dry type air-core reactor are deduced;Secondly,the calculation of the magnetic induction strength at any point in the winding space of the reactor using the Bartky transform method is given,and the eddy current loss of the reactor is calculated based on this formula,and the formulae for calculating the resistive and additional losses of the reactor are summarized.The AC composite resistance caused by the eddy current loss of the dry type air-core reactor was sorted out,and the coaxial Equivalent voltage equations for reactors;Finally,the specific design flow for AC/DC air-core reactors under isothermal ascent is given.According to the design requirements of the dry hollow-bridge reactors of Herong Electric Co.Ltd.Through the software design,the parameter design of a 37.5mH dry hollow bridge arm reactor was completed;Through the routine test and type test of the 37.5mH dry hollow bridge arm reactor designed with design parameters,the measured data is obtained.The test data conforms to the technical requirements of national standards,and it is verified that the feasibility of the isothermal rise method in the design of AC and DC current reactors.