Analysis of a model of a natural gas pipeline—a transfer function approach

A framework for natural gas pipelines is developed in a context similar to the theory of electric transmission lines. The system of semi-linear partial differential equations describing the time-dependent flow of natural gas is linearized around the steady-state flow. Additional approximations lead to a constant coefficient linear system that is equivalent to an electrical circuit that is analytically solvable and admits an ABCD matrix representation of input and output. The sinusoidal steady-state operation of natural gas pipelines is analysed including the distortion of waves. It is shown that the timing of the propagation of phases and other events is accurately represented in the approximation. The quantitative accuracy for flux and gas density of the approximation depending on different operating scenarios and depending on the frequency of the disturbances is documented.

Assessment and potential-site determination of a wheat straw power plant by Aspen Plus and multi-criteria GIS model

Wheat is one of the most important crops worldwide. Mexicali, Baja California, is an important wheat producer in Mexico with an average production of 507,543 t. Wheat straw is generated as a residue which could be used for different purposes such as bioenergy, heat and power generation. In this work, an assessment and potential site determination of a biomass power plant operating with wheat straw as fuel was performed. Aspen Plus was used to evaluate a plant capacity of at least 10 MW considering the physicochemical properties and an higher heating value of 14.86 MJ kg−1 of the wheat straw from the region. The combustion produced 39.76 MW, and the overall plant efficiency was 25.52%. The development of the multi-criteria geographic information system model allowed us to assess and analyse four factors and three restrictions to determine the potential site for the biomass power plant. The factors were raw material, wheat crops, electric transmission lines, paths and roads, water canals and aqueducts, while the restrictions were localities, Ramsar sites and faults. The biomass power plant is technically and geographically feasible. The geographical coordinates of the potential site of the biomass power plant that fulfils all the criteria are 32°29′29.72″N and 115°15′39.45″W.

The Solar Event of 14 – 15 July 2012 and Its Geoeffectiveness

During Solar Cycle 24, which started at the end of 2008, the Sun was calm, and there were not many spectacular geoeffective events. In this article, we analyze the geomagnetic storm that happened on 15 July 2012 during the 602nd anniversary of the Polish Battle of Grunwald, thus we propose this event to be called the “Battle of Grunwald Day Storm”. According to NOAA scale, it was a G3 geomagnetic storm with a southward component of the heliospheric magnetic field, $Bz$ B z , falling to −20 nT, minimum Dst index of −139 nT, AE index of 1368 nT, and Ap index of 132 nT. It was preceded by a solar flare class X1.4 on 12 July. This geomagnetic storm was associated with the fast halo coronal mass ejection at 16:48:05 UT on 12 July, first appearance in the Large Angle and Spectroscopic Coronagraph C2, with a plane-of-sky speed of 885 km s−1 and maximum of 1415 km s−1. This geomagnetic storm was classified as the fourth strongest geomagnetic storm of Solar Cycle 24. At that time, a significant growth in the failures of the Polish electric transmission lines was observed, which could have a solar origin.

MODELING OF THE PHASE TERMINATION MODE OF COMPACT ELECTRIC TRANSMISSION LINES WITH VERTICAL LOCATION OF WIRES

The article presents the results of modeling breakdown modes of one phase of a compact power line with a vertical arrangement of wires. Modeling has shown that in the out-of-phase mode transmission of large powers is possible. However, there is a significant asymmetry in the voltage at the receiving end of the power line, which requires the use of balancing devices