SAO PAULO--Ten groups plan to bid for Brazilian transmission projects at an auction to be held Wednesday, Brazil electricity regulator Aneel said Tuesday.

Brazil plans to auction licenses for six power-transmission projects, including a lot that failed to attract bidders in an auction in April. This is the second transmission auction of the year.

The bidding groups include: Abengoa Concessoes; Alupar Investimento; Cobra Instalaciones y Servicios; Chesf, a unit of state-controlled utility Eletrobras; CEEE-GT and Eletrosul, another unit of Eletrobras; Cia Paranaense de Energia, or Copel; Elecnor SA; Iberdrola-controlled Neoenergia; Orteng Energia; and Taesa, the transmission arm of utility Cemig.

Brazil is pursuing a massive expansion of its transmission network as it adds generating capacity in previously untapped regions. A plodding environmental licensing process has slowed the expansion of Brazil's transmission network, which has resulted in frequent blackouts in recent years.

The winner at these transmission auctions is determined by whichever bidder accepts the lowest annual revenue from the assets.

Brazil will auction off rights to build 678 kilometers of transmission lines, as well as build four electric substations. The projects are located in the Brazilian states of Rio Grande do Sul, Parana, Mato Grosso do Sul, Minas Gerais and Bahia.

Brazil's government-controlled utility Eletrobras swept the auction last month, taking all three lots that were bid on. The fourth lot, a 90-kilometer transmission line, received no bidders. The lot details were revised by Aneel after another study and the revised project will be included in Wednesday's auction.

Write to Paulo Winterstein at paulo.winterstein@dowjones.com