The Addicks' seven-match unbeaten run came to an end when they went down 2-0 at Bolton last weekend.
Struggling Wednesday, by contrast, had lost seven on the spin until they grabbed a 1-0 win at Yorkshire rivals Barnsley.
But Powell is hoping for a repeat of Charlton's hard-fought 1-0 victory at Hillsborough almost 12 months ago on their way to the League One title.
"We've had a terrific run and now we've got to have another one," said Powell.
"In the Championship you have a spell where everything is going for you and then you'll have a spell where it doesn't, but we really need to get back on it in Sheffield.
"We can take heart from a good run that we had and a good result that we had at Sheffield last year. We'll be straight back on it and I'm sure my group of players will do that."