| High-voltage variable frequency drives(VFDs) can output a variable AC voltage/ frequency to provide continuous over the full speed range and save energy efficiently, which catch the worldwide attention.Our group has designed Neutral Point Clamped Three-level VFD successfully,which has been passed the 6kV/2500kW tests in July,2006, in Wuhan High Voltage Research Institute and is about to run on the spot.Due to the press of energy consumption and heat scattering during the test,this paper will design a load simulator,which can set energy back to power grid,reduce the the press of energy consumption and heat scattering,and also simulate the characteristics of rotating machinery motion by using the power of electronic.Firstly,this paper introduces the history, status and trends of load simulation,then designs the structure and clarifies the general principles of simulation. According to the structure of load simulation, the paper analyses various generator types and its simulation theory, studies the converters needed in simulation in detail. As the converters must be matched with generators during simulation,we form three types of program,analyse them and select a suitable one to qua the load of VFD.For deeper analysing the program we selected initially,we chose DC generator with controllable resistance and DC generator with thyristor active inverter as the ultimate simulation objects.According to the final programs chosed,the paper will give the design of asynchronous motor and DC generator parameters , which is designed to match with the load in main circuit.By using Matlab/Simulink as a platform,we set up the simulation models-DC generator with thyristor active inverter and DC generator with controllable resistance.Simulates with the electrical parameters and load parameters designed previously.Analses the simulation results,we can find out, that can testify the design of load simulation programs and main circuit parameters are correct and reasonable. |
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