Network planning under economic aspects with special regard to reliability

Public utility companies in Western Europe are faced with rising competition by deregulation. The growing pressure of the market makes it necessary to direct investments even more strictly according to economic needs than done up to now. A big share of the investments in the field of the supply with electric energy is spent in the field of medium voltage distribution networks (10 kV-35 kV). However this voltage level in particular offers scope for a lot of additional optimisation. The present state of the art considers the reliability of customers´ supply by means of a special network topology. For many years efforts have been made to supplement or even substitute this method by a more adequate one. A very promising solution is given by probabilistic reliability indices (W. Boffo et al, 1994). The paper presents a method that results in a realistic monetarisation of the value of reliability. The customer decides on a tariff class, which commits the utility to giving financial compensation in the case of a service interruption. The customer in turn has to make monthly payments in addition to the normal-though reduced-monthly fees, whose levels also depend on the chosen tariff class