Abstract

MBULI, N.; DYANTYI, A.  and  PRETORIUS, J.H.C.. Potential for grid efficiency based on a combination of leakage reactances of transformers of a transmission interconnecting line: Application of an exhaustive search algorithm. J. energy South. Afr. [online]. 2019, vol.30, n.4, pp.1-12. ISSN 2413-3051.  http://dx.doi.org/10.17159/2413-3051/2019/v30i4a6044.

Transmission interconnecting lines (called interconnectors in this study) are built to facilitate the exchange of active and reactive power between two areas of a network. Step-up and step-down transformers are required at the ends of the interconnector when interconnectors are at a different voltage, usually higher, than the networks to be connected. A study was carried out to examine the impact on active power losses of a combination of leakage reactances of the transformers at the ends of an interconnector. The study assessed whether combinations can lead to different levels of active power losses and can thus affect the efficiency of the system. It was found that the combinations of reactance have a tangible impact on the power that flows through the inter-connector and, consequently, on the sharing of apparent power between the interconnector and the rest of the network. The total active power losses varied appreciably with the various combinations of reactances, resulting in the life-cycle cost of active power losses also varying with the combinations. The study showed that the combination needs to be carefully made, considering that such a choice can have a significant impact on techno-economic aspects of the power system.Highlights • Active power losses in power networks reduce power transfer efficiency. • Impact of coordinated choice of transformer reactances on active power losses is assessed. • Combinations of settings affect the power flow values in various lines. • Further, active power losses and costs vary as combinations of settings change. • Careful choice of reactances can enhance efficiency and reduce cost of active power losses.

Keywords : active power losses; energy efficiency; leakage reactance; life-cycle cost; net present value.

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