The Linear Filtering Reactor Integrated In The Transformer Research Based On The Non-orthogonal Decoupling Theory

With the rapid development of power industry in today’s society, problems caused by thewide use of large-scale power electronic equipment, especially harmonic issues have attractedwidespread attention. Currently, multiphase diodes, thyristors, turn-off devices such asIGBTand other power electronic devices, as rectifier system of rectifying devices,have been widelyused in ships electric propulsion, metal smelting, chemical processing, urban railtransportation, smart appliances and high-voltage DC power and other major engineering andtechnology areas, causing serious harmonic issues. Induction filtering, a new and highlyefficient power filter technology, is of the character of high harmonic filtering rate forrectifying power loads with power electronic conversion devices. Difficulty for inductionfiltering applied in ship electric propulsion and areas with strict requirements such asprefabricated substations is that the covering area of filtering hollow reactor is large while thedevice is difficult to install. In order to solve the problem of large covering area of powerfilter air-core reactor, this paper proposes a rectifier transformer integrated linear filteringreactance method based on non-orthogonal decoupling theory, which converts air-core reactordevice to transformer winding, which is installed in the rectifier transformer.For non-orthogonal decoupling theory mentioned above, this paper prepares thefollowing work:(1)Analysis of principle and implementation of non-orthogonal decoupling theory oftransformer windingsAnalyze the inductance and decoupling effect of non-orthogonal decoupling winding onpower supply winding and magnetic mechanism to achieve this effect;designa variety of non-orthogonal decoupling winding structures,including the up-down structures, internal andexternal structure and various hybrid structures; analyze the mutual inductance between non-orthogonal windings and designa testing method of the degree of windingcoupling; derivateinductance values of different non-orthogonal decoupling winding structures and inductancevaluesformula of the two decoupling windings and get inductor value of non-orthogonaldecoupling winding, error of the measured value and the design value, and actual error ofcalculated value and design value through actual test of small power transformer model.Summarize the basic principles of electromagnetic field analysis methods of non-orthogonaldecoupling winding and get the main calculating values of electromagnetic field of non-orthogonal decoupling windingand their relationships. (2)Analysis of new modeling method for integrated filtering inductance rectifiertransformerIn order to solve the existing applications and timeliness difficulty of modeling methodof the integrated filtering inductance rectifier transformer, this paper studies a new magnet-circuit coupling calculation method that treats inductance matrix as anintermediate variableand elaborates the idea and practical application steps of this design. Establish a magneticfield model for rectifier transformer, obtain transformer windings inductance matrix, get thewinding state power equation that treats inductance matrix as the core argument by writingwinding voltage equations, proposes an idea of calculating the values of the transformer undervarious situations with various port conditions; calculate short-circuit impedance oftransformer prototype based on the calculating idea of new magnet-circuit couplingcalculation method and get multiple short-circuit impedance of transformerprototype; derivatecircuit model for three-phase fundamental and harmonic of integrated filtering inductancerectifier transformer; construct a circuit software simulation model by using the inductancematrix as the core component, get current simulation waveforms of each phase and currentwaveform of each winding in the low voltage side of the transformer prototype model;compare the theoretical current waveforms; obtain the actual operation of the transformerprototype by making300kVA integrated filtering inductance rectifier transformer, filtering,reactive power compensation system and carrying out the state test of the actual operation;compare with modeling simulation and ensure the correctness of the new magnet-circuitcoupling calculation method.(3)Derivation of the design of300kVA integrated filtering inductance rectifiertransformer prototypeAnalyze operational requirements of ship power system, make specific analysis ofmeasures taken for the system volume and get the transformer substation box size; givetransformer noise calculation formulas to derive prototype noise design value; refer tonational standards of power quality utility grid harmonics to get the allow able value ofharmonic current of prototype to enter each common connection point; give the simplifieddesign for transformer prototype and its system equipment; present the prototype windingsarrangement and experimental prototype system structure of power supply system consists ofrectifier transformerprototypes; analyze and summarize a variety of decoupling technologiesto integrate reactor windings into rectifier transformer; make a detailed analysis oftheharmonic by pass ways of transformer inductive filtering winding; give rectification schemeof the system prototype and technical assessment indicators. Carry out design guidelines ontransformer, filter, and atone system through the writing of system boundary conditions. Make detailed analysis of transformer and its system design and manufacturingprocess,including the core size calculation of the transformer, calculation of the reactorwindings inductance value and the winding size, calculation of winding turns, its short-circuitimpedance, and winding size, calculation of overall device loss and its weight, and calculationof reactive power compensation and branch capacitor distribution.(4)Making a300kVA integrated filtering inductance rectifier transformer prototype, andusing it as the core component to build experiment system of power supplying, filtering andreactive power compensationMeasure the inductance values, linearity and winding coupled degree of prototypereactor winding; measure the high side power factor before and after switching the filteringdevice when the prototype is at rated load operating state, the harmonic current content andharmonic current distortion; measure voltage and current of vectors of the5th, the7th and the11th. Verify the accuracy and linearity of integrated linear reactor winding by non-orthogonaldecoupling theory structure of its and its characteristics to completely decouple with otherwindings. To verify the filter device consisting of integrated linear reactance winding andcapacitors each harmonic time to achieve reactive power compensation and harmonic filteringon the prototype;verify normal work of the integrated reactor windings.Test results show thatthe non-orthogonal decoupling theory is correct, the inductance value is accurate and it hasachieved filtering effect of300kVA integrated filtering inductance rectifier transformerprototype based on non-orthogonal decoupling theory.