An energy consortium led by a Northern California company was awarded a contract to build a $300 million electrical generating station in Sri Lanka.

Mihaly International Corp. of Mill Valley expects to build what will be the island nation's first-ever build-operate-and-transfer facility."Right now we're completing financing work on the project. We have to do a final pricing on the boiler before we can apply for export credits," said Eugene Mihaly, company president.

Proposed financing for the project is to include export credits from several countries, loans from the World Bank and the Asian Development Bank, and equity stakes.

The contract was the result of several months of effort. While Mr. Mihaly hoped to begin construction of the double unit power station in January, construction more likely will start in the third quarter of 1994. Completion of the first unit is expected in early 1988 and the second the following year.

The proposed power plant is the product of a World Bank study undertaken during the mid-1980s. Originally, the project was to be a government affair but was revised for a privatized approach.

Sri Lanka solicited proposals from nearly two dozen companies before selecting Mihaly International, an investment firm specializing in capital projects in development countries.

The consortium includes Coal & Allied Industries Ltd. of Australia; Asea Brown Boveri, a Swiss and Swedish enterprise; Nissho Iwai of Japan; Ontario Hydro of Canada; Development Resources Ltd., a subsidiary of the Singapore Public Utilities Board; and Gundy and Associates Ltd. of Canada.

Monenco-Agra of Oakville, Ontario, will manage the design and construction phase of the project. A new utility company, the South Asia Electric Corp., will oversee plant operations and revenue collections.

After 15 years, ownership of the coal fire plant, which is to be located in the eastern port city of Trincomalee, would be turned over to the Ceylon Electricity Board.