Adaptive Impedance Relay with Composite Polarizing Voltage
Fault resistance can bring some disadvantages for an impedance relay while a single-phase-to-ground fault occurs on transmission line. Taking advantage of the compensated voltage changing with fault resistance, this paper presents a kind of adaptive impedance relay with composite polarizing voltage to enhance the capability against fault resistance. On the other hand, the operating boundary of the adaptive relay may enter into "in-phase" region along with the increase of fault resistance. To prevent the adaptive relay from the "in-phase" problem, a new additional blocking component is proposed in this paper. Both the adaptive relay and the blocking component are all analyzed in the voltage plane and the impedance plane. Theoretical analyses show that both of them have circular characteristics with greater resistive tolerance. The performance of the relay has been demonstrated on a two-source 500 km line 750 kV system.
TWO NEW EARTH-FAULT REACTANCE RELAYS BASED ON FAULT-COMPONENT
Based on the theoretical analysis of high-resistance earth-fault characteristics of HV/EHV transmission line, two kinds of new type earth-fault reactance relays based on fault-component are proposed in this paper, these relays can overcome the overreach problem existed in the earth-fault distance protection with excellent performance within the protective zone. The steady-state characteristics of these protective relays are studied thoroughly in the paper.
Mesozoic rifting and basin inversion along the northern African Tethyan margin: an overview
Abstract The northern African Tethyan margin registered three major rifting episodes from the latest Palaeozoic-earliest Mesozoic to the earliest Cenozoic. Break-up of Gondwana was initiated in the late Carboniferous. Along the northern African-Arabian plate margin rifting propagated westward from the northeastern Arabian margin to Morocco during the Permian and Triassic, and was accompanied by Mid-Late Triassic-earliest Liassic extensive alkaline flow basalts. Rifting continued during the Liassic, e.g. in the Moghrebian Atlas troughs. A second stage of rifting occurred in the Late Jurassic and continued into, or was rejuvenated during, the Early Cretaceous. Along the east Mediterranean margin, some large E-W trending rifts formed, often with associated volcanism, e.g. southern Sirt and Abu Gharadig. Most researchers believe the oceanization of the eastern Mediterranean basin occurred at this time. Flexural subsidence affected the Moghrebian Atlas, including the Riffian-Tellian domain, where a thick flysch series was deposited. Two short-lived, but widespread and tectonically important, compressional or wrench-dominated events occurred during the Santonian and the latest Maastrichtian. From Morocco to Oman, most sedimentary basins were folded and inverted at these times. The Santonian event resulted from onset of the collision between the African-Arabian and Eurasian plates. New stress-fields favoured NE-SW extension along the African plate margin, generating or rejuvenating some rifts, e.g. in the Euphrates trough and in the Libya-Tunisia region (northwestern Sirt, Pelagian Sea). Rifting and magmatism continued in these regions into the Paleocene. During the Mesozoic, therefore, the northern margin of the African-Arabian plate registered both rifting resulting in the oceanization of the Tethys and rifting resulting from the initiation of the closure of the Tethys. The intraplate domain exhibited echoes of the tectonic events affecting the margin.