Perez said the winning bidder will provide a system that will be used by the autonomous market group operator (AGMO) to run the WESM.
The four pre-qualified companies are: Asea Brown Boveri (ABB), Siemens AG of Germany, Alstom and Logica of the UK.
Perez said they will set the bidding schedule soon. "We are now in the selection process and most probably we could announce the winning bidder by the end of April. And by September, we can start with the interim operation of WESM," he said.
He said the system to be used by AGMO should be determined alongside with the drafting of the WESM rules which will probably be finished by April this year.
Under the Electric Power Industry Reform Act or Republic Act 9136, WESM should be in place before the sale of the generation assets of the National Power Corp. (Napocor) in the last quarter of this year or early next year.
Envisioned to operate like the local stock market, WESM would provide procedures for establishing the merit order dispatch of power for each time period.
It would also determine the market-clearing price for each time period and administer the market. The WESM is also expected to prescribe guidelines for the market operations in system emergencies.
The independent market operator will also oversee the transaction billing settlement procedures.
Under the new power bill, the WESM should be run by an independent body while the Department of Energy (DOE) will just function as an implementing agency.