voltage is not a constant... it does vary, but your appliances and devices are designed to use varying voltages just fine... no worries. While some will purchase devices to try to 'keep' the voltage constant, most of us do not worry about it - after 100,000+ miles across this country, including Alaska, and most of Canada, and having 'plugged in' to many, many, many rv parks, campgrounds, regular household outlets, and even 'suspect' campground sources, we've never had any issues with 'voltage'. If voltage drops, amperage increases, so it's quite possible a breaker could trip sooner than otherwise, usually the main Shore Power breaker, but that's it's job, regardless.
'14 Palazzo 33.3 bunkhouse 34' diesel
KingTailgater2 Dish HD, 100w/5a SOLAR, BlueOx
100,000+mi since '14 - US, Alaska, Canada - Northwest, GA! (also, '14 Gulfstream Amerilite and '07 ForestRiver Rockwood) : )