Alliant Energy Corp. said it has completed the sale of three power plants in China to a company in Thailand. Madison, Wis.-based Alliant sold the plants to Banpu PLC for about $74 million, and Alliant was released from its $15 million of debt associated with the plants. Alliant said it is selling its overseas investments to focus on customers in Wisconsin and Iowa. It is the parent of Wisconsin Power and Light Co. and Interstate Power and Light Co.