This article is for the public purpose of promoting the increased use of electricity in the urban and rural areas of this state, and of enabling the residents thereof to secure the benefit of the surplus power generated or to be generated by the Tennessee Valley Authority at Wilson Dam in the State of Alabama, or the power generated at any other works or dams. The powers granted by this article shall be liberally construed to effectuate the purposes hereof, and to this end every district shall have power to do all things necessary or convenient to carry out the purposes hereof in addition to the powers expressly conferred in this article. This article is complete in itself and shall be controlling. The provisions of any other law, general, special or local, except as provided in this article, shall not limit or restrict the powers granted by this article.