Unbundling of transmission and ancillary services. I. Technical issues

This paper presents derivations of basic formulae for computing the contributions of each economic transaction to the network power flows throughout the system in steady-state operation of interconnected electric power systems. It is shown that the net system power imbalance caused by each transaction can be obtained as a function of all transactions present on the system. In addition, formulae are proposed for calculating the contributions of every ancillary generation unit to each transaction. This generation is needed to balance the system in response to economic transactions. Formulae supporting this are based on reformulating the load flow problem in terms of distributed slack bus.