Why do we stand while saying (or singing) mizmor 29 (…havu laShem b’nei ailim) during kabbalas Shabbos?
The siddur HaShelah says that since the Gemara in Berachos says (if you would come to the Shabbos Ayn Yaakov shiur, you would know this) (also if you have been attending Rabbi Jacobson’s shiur) (also , if you will be attending Rabbi Padowitz’s NEW Gemara shiur, you WILL be learning this)…
…where was I
Oh yes…that the 18 (original) berachos in Shemoneh Essrai corresponds to the 18 times HaShem’s Name is mentioned in this mizmor. And so since this mizmor is the source and inspiration for Shemoneh Essrai, we stand when we say it (during davening), just as we stand for Shemoneh Essrai.