Analyzing techniques for increasing power transfer in the electric grid

Abstract

The worldwide demand for electric energy is slated to increase by 80% between the years 1990 and 2040. In order to satisfy this increase in load, many new generators and transmission lines are planned. Implementations of various plans that can augment existing infrastructure have been hindered due to environmental constraints, public opposition and difficulties in obtaining right-of-way. As a result, stress on the present electrical infrastructure has increased, resulting in congestion within the system. The aim of this research is to analyze three techniques that could improve the power transfer capability of the present electric grid. These include line compaction, use of high temperature low sag conductors and high phase order systems. The above methods were selected as they could be readily employed without the need for additional right-of-way.Results from the line compaction tests indicate that line compaction up to 30% is possible and this increases the power transfer capability up to 53%. Additional advantages of employing line compaction are the reduction in electric and magnetic fields, increase in system stability and better voltage regulation.High temperature low sag conductors that were applied on thermally limited lines were seen to increase the power transfer capability. However, a disadvantage of this technique was that the second most congested line, limits the power transfer capability of the system.ii High phase (six phase) order system was noted to have several advantages over three phase system such as lower voltage requirement to transfer equal amount of power and lower electric and magnetic field across the right of way.An IEEE 9 and 118 bus test system were used to evaluate the above mentioned techniques.iii ACKNOWLEDGEMENTS

Uprating of transmission lines by means of HTLS conductors for a sustainable growth: Challenges, opportunities, and research needs

“…Therefore, HTLS conductors have great potential for replacing conventional ACSR and AAAC conductors [11]. Although HTLS conductors allow increasing power transfer capability, there are other systems to do so, such as the use of compact transmission lines or high phase order (six phase) systems [43], although such methods require replacing or extensive modifications of the existing structures.…”

“…In an overhead power line, the sag is the vertical distance from the midpoint of the span and the straight line connecting the two support points of the conductor [47]. Transmission structures are calculated such that phase to tower and phase to phase clearances must withstand voltage surges, galloping and swinging of conductors during any weather condition [43]. Excessive sagging due to high temperature or insufficient current carrying capacity can lead to a complete blackout [21], so HTLS conductors allow addressing this issue.…”

Transformation of a three‐phase double‐circuit overhead transmission line into a six‐phase feeder to increase power transfer capability

“…The viability was successfully demonstrated in the 1992 New York trial, when the 115 kV 3Φ double-circuit Goudey-Oakdale line was transformed into a 93 kV 6Φ line and operated commercially for three years [9]. This trial accumulated valuable operational experience and instigated others to investigate the technical issues and challenges associated with 6Φ transmission, including tower design [5,[10][11][12], transformer configuration and ferroresonance [8,13,14], transient stability [15][16][17][18], economics [19], fault analysis [20,21], relay protection [22][23][24], electromagnetic field [6,7,12,[25][26][27], noise [6,7,[25][26][27] and insulation coordination [7,27]. One of the major technical challenges is the need to add transformers at each line end to convert the three-phases into six-phases operating at an elevated phase-to-neutral voltage.…”