A model for reactive power tracing by addition of fictitious nodal injections

This paper proposes an efficient solution to the problem of reactive power flow tracing in electrical transmission networks. For such systems, the tracing techniques used for active power flows cannot be used straightforwardly, due to reactive power variations induced by the line reactances, these variations often being comparable to the powers delivered to the loads. In other words, as is well known, in transmission systems the reactive flows are strongly influenced by the inductive and capacitive effects of the network, making the tracing of power flow and allocation of losses more critical. In this paper, after discussing some methodological aspects, an approach based on the use of transmission line models differentiated on the basis of the reactive behaviour of the lines is proposed. These models allow the power contributions due to reactive losses to be evaluated separately and compared to the flows exchanged between generators and loads; moreover, their application does not require the introduction of nodes or additional links, as is the case with other methods proposed in the literature. The proposed tracing technique is then presented; the method is straightforward and does not require the creation or inversion of matrices of participation factors. The paper concludes with two applications, a 4 node system and the IEEE test system with 30 nodes.