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Recently, studies of squirrel-cage induction machines validate the idea that these machines follow the double-cage induction model; however, the manufacturers categorize these machines as single-cage machines. There are many references that use the squirrel-model for squirrel-cage machines, then machine parameters increase from 5 to 7. In the laboratory, parameter determination is performed to estimate 5 parameters; however, 7 parameters have to be determined. Also, the DC test is not an exact test and is used for approximate estimation. Therefore, locked rotor test equations are changed and an overload test is added. After measurements in the laboratory according to the equations of this paper, a MATLAB program is prepared and 7 parameters are determined in a loop until reaching the desired error. This paper demonstrates that laboratory squirrel-cage machines have to be corrected using the 7-parameter model. Furthermore, this paper shows the necessity of new laboratory test equations for squirrel-cage machines. Then a numerical method is used to determine the machine parameters. [ABSTRACT FROM AUTHOR]

As wind energy is one of the low cost renewable energies and wind turbines are simple and reliable, wind power plants are very noteworthy power electricity sources. Nowadays doubly fed induction machine is vastly applied in wind power plants instead of other electric machines. In this paper, a doubly-fed induction generator with winding-rotor configuration, an external rotor resistance and a modeled voltage source inverter that has an adjustable phase and amplitude is used and controlled first time by a PI self tuning voltage controller and second time by a P self tuning voltage controller and a pitch controller as the combinational controller to control the output active and reactive powers. The performance of controllers is compared. Furthermore, the doubly-fed induction machine is simulated with an improved wind turbine maximum power tracking system for different wind speeds. Results show that PI self tuning controller is technically better with lower cost but P controller has better dynamic output responses and can be better for wind plants with pitch control technology to promote the strategy of controlling by a combinational controller. [ABSTRACT FROM AUTHOR]