Returns portfolios with U12 and U20 generators removed and generators
    of the same type at the same bus aggregated.

def get_portfolios3():
    """ Returns portfolios with U12 and U20 generators removed and generators
    of the same type at the same bus aggregated.
    """
    g1 = [0]
    g2 = [1]
    g7 = [2]
    g13 = [3]
    g14 = [4] # sync cond
    g15 = [5]
    g16 = [6]
    g18 = [7]
    g21 = [8]
    g22 = [9]
    g23 = [10, 11]

    portfolios = [g1 + g15 + g18,
                  g2 + g16 + g21,
                  g13 + g22,
                  g7 + g23]

    passive = g14 # sync_cond

    return portfolios, passive