Question 4.AE.5: A permanent-magnet generator is designed [29,30]for a variab......
A permanent-magnet generator is designed [29,30]for a variable-speed drive of a wind-power plant without any mechanical gear. The rated speed range is from 60 to 120 rpm. Line-toneutral voltages v_{L-N} and line-to-line voltages v_{L-L} are recorded at no load and under rated load. The voltage wave shapes are subjected to a Fourier analysis. Figures E4.5.1 and E4.5.2 depict the line-to-neutral voltages at no load and rated load, respectively, and Tables E4.5.1 and E4.5.2 represent their Fourier coefficients. Figures E4.5.3 and E4.5.4 represent the line-to-line voltages at no load and at rated load, and Tables E4.5.3 and E4.5.4 list their spectra. To minimize the size of this low-speed generator, the stator pitch k_p and distribution k_d winding factors are chosen relatively high (k_p . k_d=0.8) resulting in a somewhat nonsinusoidal voltage wave shape. The generator feeds a rectifier and for this reason the nonsinusoidal voltage wave shape does not matter, except it increases the generator losses within acceptable limits.
Table E4.5.1 Harmonic Spectrum of Fig. E4.5.1
\begin{array}{l|r|r|l}\text{Harmonic order}&\text{Harmonic magnitude }(\%)&\text{Harmonic order}&\text{ Harmonic magnitude }(\%)\\ \hline 1 & 100 & 7 & 3 \\ 2 & 0 & 8 & 0 \\ 3 & 11 & 9 & 8 \\ 4 & 0 & 10 & 0 \\ 5 & 1 & 11 & 7 \\ 6 & 0 & 12 & 0 \\ \hline \end{array}
Table E4.5.2 Harmonic Spectrum of Fig. E4.5.2
\begin{array}{l|r|r|l}\text{Harmonic order}&\text{Harmonic magnitude }(\%)&\text{Harmonic order}&\text{ Harmonic magnitude }(\%)\\ \hline 1 & 100 & 7 & 2 \\ 2 & 0 & 8 & 0 \\ 3 & 14 & 9 & 7 \\ 4 & 0 & 10 & 0 \\ 5 & 1 & 11 & 5 \\ 6 & 0 & 12 & 0 \\ \hline \end{array}
Table E4.5.3 Harmonic Spectrum of Fig. E4.5.3
\begin{array}{l|r|l|l}\text{Harmonic order}&\text{Harmonic magnitude }(\%)&\text{Harmonic order}&\text{ Harmonic magnitude }(\%)\\ \hline 1 & 100 & 7 & 3 \\ 2 & 1 & 8 & 0 \\ 3 & 0 & 9 & 0 \\ 4 & 1 & 10 & 0 \\ 5 & 1 & 11 & 6 \\ 6 & 0 & 12 & 0 \\ \hline \end{array}
Table E4.5.4 Harmonic Spectrum of Fig. E4.5.4
\begin{array}{l|r|r|l}\text{Harmonic order}&\text{Harmonic magnitude }(\%)&\text{Harmonic order}&\text{ Harmonic magnitude }(\%)\\ \hline 1 & 100 & 7 & 3 \\ 2 & 1 & 8 & 0 \\ 3 & 1 & 9 & 0 \\ 4 & 0 & 10 & 0 \\ 5 & 1 & 11 & 6 \\ 6 & 0 & 12 & 0 \\ \hline \end{array}
