This chapter may not:
(1) interfere with or abrogate the rights or obligations of any party, including a retail or wholesale customer, to a contract with an investor-owned electric utility, river authority, municipally owned utility, or electric cooperative;
(2) interfere with or abrogate the rights or obligations of a party under a contract or agreement concerning certificated utility service areas; or
(3) result in a change in wholesale power costs to wholesale customers in Texas purchasing electricity under wholesale power contracts the pricing provisions of which are based on formulary rates, fuel adjustments, or average system costs.