The largest and oldest power cooperative in Texas is filing for Chapter 11 bankruptcy protection citing last month’s winter storm that left millions without power. Brazos Electric Power, which serves 16 distribution member cooperatives that cater to more than 1.5 million Texans, said Monday that it was a “financially robust, stable company” prior to the severe cold weather that hit Texas between February 13 and February 19. Brazos said that it received excessively high invoices from the Electric Reliability Council of Texas for collateral and for purported cost of electric service. Brazos says it’s decided not to pass on the ERCOT costs to its members or the consumers.