What is the use of No of harmonics option in PSS form

 Hi,

In PSS form, there is one option called Number of harmonics. I am NOT able to understand what is its use as PSS is any way a Steady state DC operating point analysis ?

Of course, No of harmonics actually controls the time step for better accuracy (like to avoid Aliasing effect etc). But the time step can easily controlled by maxacfreq OPTION.

 So my doubt is:- Whether the Harmonic Option in PSS form is needed for Some other reasons ?

IS there any documents which actually explains the need/use (OTHER than controlling Time Step) of No. of Harmonics option in PSS form

Thanks