Research On Rank Difference And Working Characteristics For Pulling Into Step Of Double-fed Speed Regulating System

Based on through investigation and analysis, for the purpose of expansion to the coal mine fans and pumps old winding motor, combined with the six pulses double-variables cycloconverter, researched on the double-fed system basic principle, rank difference and working characteristics for pulling into step.Firstly, introduced the double-variables control theory, and presents the double-variables definite methods through the 1/3 frequency. Then analysised basic working principle of double-fed system, study the rotor-side inverter supply on the impact of double-fed system, and analysis five operation status based on motor vector and power flow diagram. Then according to the mine winding motor operating requirements, put forward the piecewise differential control strategy, obtained the maximum speed differential for pulling into step and speed stage head table and characteristic curve. Also established the system simulation model, optimized start-up circuit design, verified the feasibility of the double-fed starting and the maximum speed differential. Then based on double-fed speed regulation system to achieve the performance requirements, designed double-fed start-up system and loading system. Finally advanced experiment contents included double-fed system, regulation characteristics, dynamic process from electric to genaration, got the maximum permissible speed differential for pulling into step about 4% rated speed, verified theory and simulation results. Researched double-fed system working characteristic based on steady-state operation, got V-sharped curve under different conditions. The result of experiment indicates that the double-fed system can get a better running state, and can meet the two demands of energy conservation and alteration of increasing capacitance.