Centrica

Abstract: Abstract The development of the central Tauride region was dominated by rifting and passive margin development during Triassic–Early Cretaceous. The Tauride continental margin was later destabilized, followed by subsidence and collapse to form a flexurally controlled foredeep. Volcanic–sedimentary mélange and ophiolitic rocks were thrust onto the northern margin of the Tauride carbonate platform (Geyik Dağ) during Campanian–Maastrichtian. The remaining non-emplaced Tauride shelf subsided to form a second-stage foredeep during the Eocene. This basin was finally over-ridden by large thrust slices of Tauride shelf sediments, represented by the Hadim and Bolkar nappes, together with previously emplaced continental margin and ophiolitic units. Large- and small-scale field kinematic data indicate regional emplacement towards the west or SW. The ophiolitic rocks and related mélange were emplaced directly onto the Tauride autochthon (Geyik Dağ) in response to regional-scale out-of-sequence thrusting. Localized backthrusting to the NE took place in a transpressive setting. In the south, the relatively distal Bolkar nappe was emplaced over the more proximal Hadim nappe to produce the present thrust stacking order. The two-phase emplacement reflects initial northward subduction, which culminated in trench-continental margin collision (Campanian–Maastrichtian). This was followed by continent–continent collision (Eocene) related to suturing of a Mesozoic ocean basin to the north.

Abstract: Transformer energisation is a common practice for the transmission of high voltage electrical power over long distances. Switching large power transformers arbitrarily on a system with high impedance or relatively low fault current levels drives the transformer core into saturation resulting in high inrush currents [1]. The magnitude of inrush currents can be very high especially when the transformer core has residual flux which adds to the core flux build-up after energisation [2]. This inrush current results in voltage drop at the transmission network and the level of voltage drop depends on the short-circuit MVA level at the source bus and the magnitude of the transient inrush current. This paper is based on a real time event that took place at Langage Power Station located in the south west peninsula of the UK in January 2010. Two high voltage generator step-up transformers were energised simultaneously resulting in high voltage drop at the transmission network thereby affecting the power quality of the system. A detailed MATLAB model has been developed to simulate the switching event. Simulations were carried out considering different system conditions to clearly demonstrate the impact of inrush current on voltage drop. The results have been produced for different scenarios considering various factors such as system impedance, residual flux and short circuit MVA level at the source network which would impact on the magnitudes of inrush and sympathetic inrush currents. Suitable mitigating measures were recommended and the advantages and disadvantages of each of the measures have also been discussed.