The Research On Synthesis Energy Saving Theory And New Method Of The Large-power Rectifier System

The industrial application of large-power rectifier system based on the AC/DCenergy convention has become an important part of the national industry. Under thebackground of high electricity price and mandatory implementation of energy saving forindustrial enterprises, the high energy-consuming industries must face the problem ofenergy saving. In this thesis, the conventional diode uncontrolled rectifiers and thyristorphase-controlled industry rectifiers system are analyzed, and a new DC power supplysystem based on an inductive filtering technology is presented. The inductive filteringmethod and its implementation condition are analyzed. According to the followingpractical problems: accurate measurements of the large direct current and efficiencymonitor of the system and key equipments, a synthesis energy saving theory and newmethod of the large-power rectifier system is presented. The projective test results showthe technical superiority of the new rectifier system on harmonic suppression and energysaving.For the synthesis energy saving theory and new method, the performed fundamentalresearch and the related innovative achievement in this thesis are summarized asfollows:(1) The equivalent-circuit model of the large-power rectifier system and theharmonic-transfer mathematical model of the transformer are established. Theharmonic characteristic of the rectifier with the commutation and finite link inductanceis analyzed. Based on the conventional large-power rectifier system and its harmonicsuppression and reactive power compensation methods, a new industry rectifier systembased on inductive filtering technology is presented. Furthermore, its main-circuittopologies are analyzed, and the equivalent-circuit model of the rectifier system,harmonic transfer mathematical model of the transformers and the system loss model areestablished to analyze harmonic transfer characteristics and key equipments’ loss.Moreover, the harmonic power and its influence on electric energy measurement isdiscussed.(2) A new indirect measuring method of large direct current is presented.Considering the conventional measuring method and related problems, the relationshipbetween the current of valve side and DC side are deduced and analyzed by theelectromagnetic coupling transient model, switch function method and classic analytic calculation approach. Then, considering the effect of the valve pressure drop, loss andresistor-condenser circuit on the DC, a detailed measuring scheme is presented from thewaveforms measuring of transformer valve currents to direct current inversion andcalculation, and had obtained the national invention patent. This method has theadvantages of simple calculation, rejecting the bulky dc sensor, and no the influence ofthe DC strong magnetic field.(3) Real-time monitoring and analysis method of the key equipments andsystem loss and efficiency on the larger-power rectifier system is proposed. Thelarger-power rectifier system consist of regulating and rectifier transformer, rectifier andfilters. Therfore, a monitoring method for the rectifier system’s real-time loss ispresented by the simultaneous measurement of the voltage and current of the AC gridside, filtering side, valve side, and DC side. Then, the engineering testing is developed.Meantime, the problems of operating efficiency testing of the power rectifier equipment,sensor accuracy, synchronous measurement and rectifier loss engineering testing areanalysed and researched. Finally, according to the corresponding national standards of P.R. China, the testing results and their error correction are processed. It can be used tosolve the problems of power supply equipments and system’s efficiency accounting, andprovide date for the assessment of energy saving.(4) A synthesis energy saving scheme of the non-harmonic pollution and energysaving DC power supply system is analyzed. In the basis of the prior study, the energysaving technology are researched as follows: inductive filteing method energy saving,including harmonic suppression reactive power compensation nearby harmonic andreactive power sources; energy saving of the system parameters optimum design; energysaving of the key equipments optimum design and system operations control energysaving based on the real-time monitoring of the key equipments’ loss. It is expected tosolve the existing problems of serious harmonic pollution and larger losses on thelarge-power rectifier system.(5) The projective application of inductive filtering in6-pulse and12-pulselarge-power rectifier system is researched. The inductive filtering method has beenapplied in a6-pulse industrial rectifier system (DC voltage is415V, DC current is22kA),and a12-pulse industrial rectifier system (DC voltage is640V, DC current is16kA). Inthis thesis, the electric wiring scheme of the two industrial rectifier system, theconfiguration and the main design parameters of the inductive filtering rectifiertransformers and their related full-tuned branches are introduced, respectively.Furthermore, the practical characteristic harmonic impedance parameters of full-tuned branches are presented. Finally, the field test on the two large-power rectifier systemsare performed respectively to verify the effectiveness of harmonic suppression andenergy saving.