REAL-TIME POWER INTERCHANGE BETWEEN NEIGHBOURING UTILITIES A CASE STUDY OF WAPDA & KESC

In Pakistan, the function of power generation, transmission and distribution is shared between two utilities, i.e WAPDA & KESC. The area of franchise of WAPDA, which is a predominantly hyde7 utility, extends over the whole of Pakistan except the city of Karachi, while KESC, which is purely thermal, has a franchise covering Karachi and its suburbs. Both WAPDA and KESC have less insta71ed capacity than required to meet demand and maintain adequate reserve margins. The shortfall is more pronounced for WAPDA, where forced power cuts are regularly imposed on various categories of consumers,specia77y during lean hyde7 periods. Although both utilities are interconnected by a 600 MW double circuit 220 KV transmission lines, the two systems are normally operated in isolation, with only occasional transfer of power over the interconnecting link. This paper investigates the economic advantages which would accrue if WAPDA and KESC power systems are operated as one integrated system, and a common merit order formulated for despatch of the combined generation pool. It is shown that for a given system reliability and reserve margin, fully integrated operations of the two utilities would result in a reduction in investment outlay for generation expansion of US$ 1.7 billion over the period 1990-99, annual fuel cost savings to the tune of US$ 128 million, and reduction in ENS failure cost of the order of US$ 43 million annually. In view of administrative and political difficulties in enforcing fully integrated operations, the paper presents a concept of real time interchange of power over the in te rconnec tors, using as an instrument of interchange a predetermined hourly interchange tariff basE incrementa 7 generation costs. The concept of predetermined tat i i ls allows most of the benefits accruing from fully integrated operations to be realized, and is considered workable in the context of third world utilities like WAPDA and KESC, where the despatchers do not have the ompetence, training, or even the authority to quote spot rates for surplus power, or to make real time decisions wether to buy at the price quoted by the other utility, as in the case of European and American operations to be realized, and is considered workable in the context of third world utilities Like WAPDA and KESC, where the despatchers do not have the competence, training, or even the authority to quote spot rates for surplus power, or to make real time decisions wether to buy at the price quoted by the other utility, as in the case of European and American interconnected networks.