The Owls strengthened their ranks over the summer before completing the signing of Derby County midfielder Jacob Butterfield on deadline day.
New arrivals included centre-backs Joost van Aken and Frederico Venancio, which Carvalhal hopes will help Wednesday secure Premier League promotion, having narrowly missed out in the previous two campaigns.
"I am very happy with Jacob because he is a quality midfielder and one I have appreciated since I have been in England," the Owls boss told Sky Sports News.
"Van Aken comes from the Netherlands, a centre-back... with a bright future. He is tall and a very good header [of the ball], fantastically technical in playing the ball out from the back with his left foot.
"He has very good quality but maybe needs older players, like Frederico Venancio. With these two players we have covered the position of centre-back and now we have four and we are very happy with all of them.
"This season we have one more point than this time last season and we believe we will grow as a team. The transfer window has now finished and believe me, that was not easy."
Wednesday were last in the Premier League in the 1999-2000 season, and have yo-yoed between the second and third divisions since then.