The Kentucky Public Service Commission has tentatively approved the purchase of Louisville Gas and Electric Company and Kentucky Utilities by Pennsylvania-based PPL Corp.The PSC today announced approval of a settlement involving a number of groups that intervened in the case. PPL has agreed not to raise base utility rates before the end of 2012. The company earlier pledged to keep LG&E and KU headquarters in place for at least 15 years. PPL announced in April that it had reached an agreement to purchase the utilities from E.ON U.S. for $7.6 billion. Louisville and state officials made a bid for public ownership of the companies but could not come to final terms.