From 1966 to 1974 he worked at Leeds and Northrup Company in Philadelphia, PA where he was responsible for development of an operator power flow, constrained economic dispatch and contingency analysis software. From 1974 to 1984 he worked at Power Technologies Incorporated in Schenectady NY where he was responsible for development of PTI's Power System Simulator for Operations. He conducted research on optimal power flow, contingency selection, power system planning software, cost benefit studies for energy management systems, and advanced state estimation algorithms. Dr. Wollenberg also served as an adjunct Professor in the Electric Power Engineering Department at Rensselaer Polytechnic Institute from 1979 to 1984.

From 1984 to 1989 he worked at Control Data Corporation's Energy Management Systems Division in Plymouth MN where he was responsible for development of Artificial Intelligence Applications. He consulted on advanced research projects in energy management system application software and he participated in the power system operator training simulator project for the Electric Power Research Institute. Dr. Wollenberg was also active in teaching as an adjunct Professor in the Electrical Engineering Department at the University of Minnesota from 1984 to 1989.

In 1989 he was appointed to a professorship at the University of Minnesota in Minneapolis MN where his current interests involve the development of large scale network solution algorithms using vector processing supercomputers, the extension of traditional power system control techniques to incorporate spot pricing algorithms and distributed computing technologies, the application of expert systems to enhance the information presented to power system operators using real time computers.

He is the coauthor with Allen Wood of the Wiley textbook Power Generation Operation and Control.

Professor Wollenberg is a Fellow of the IEEE. He is a member of Tau Beta Pi, Eta Kappa Nu and Sigma Xi honorary societies and he is the former Chair of the Power Systems Engineering Committee of the IEEE Power Engineering Society.