A Method of Analysis of Power Line Carrier Problems on Three-Phase Lines

Perz, M. C.

doi:10.1109/tpas.1964.4766060

Cited by 21 publications

(3 citation statements)

References 5 publications

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“…Seminal experimental work in the 1960’s and 1970’s verified the existence of low latency and low attenuation aerial modes of propagation on EHV transmission lines 15 – 19 . These aerial modes are responsible for long distance communication in PLC systems, which has subsequently been used commercially for several decades in protective relaying applications on transmission networks.…”

Section: Electrical Transmission Grids As Precision Timing Networkmentioning

confidence: 98%

A sub-μs accuracy GPS alternative using electrical transmission grids as precision timing networks

Robson,

Haddad

2024

Sci Rep

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It is widely recognised that over-reliance on GNSS (e.g GPS) for time synchronisation represents an acute threat to modern society, and a diversity of alternatives are required to mitigate the threat of an outage. This paper proposes a GNSS alternative using time dissemination over national scale transmission or distribution networks. The method utilises the same frequency bandwidth and coupling technology as established power line carrier technology in conjunction with modern chirp Spread Spectrum modulation. The basis of the method is the transmission of a time synchronised chirp from a central substation, coupled into the aerial modes of the transmission line. During GNSS operation, all substations can estimate the time of flight by correlating the received chirp with a time-synchronised local copy. During GNSS outage, time sychronisation to the central substation is maintained by correcting for the precalculated time of flight. It is shown that recent advances in chirp spread spectrum allow for a computationally efficient algorithm with the capacity to compute hundreds of thousand of chirp correlations every second, facilitating timing accuracy which satisfies the majority of smart grid applications. ATP-EMTP simulations of the method on large transmission networks demonstrate sub-μs timing accuracy even in the presence of low SNR and impulsive noise. An FPGA prototype demonstrates experimentally sub-μs accuracy for time dissemination over a distance of 700 m. Averaging over time is shown to facilitate satisfactory performance down to $$-20\,\hbox {dB}$$ - 20 dB , which could extend the range of the system to a national scale and a time dissemination network invulnerable to wireless spoofing and jamming attack vectors.

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Section: Electrical Transmission Grids As Precision Timing Networkmentioning

confidence: 98%

A sub-μs accuracy GPS alternative using electrical transmission grids as precision timing networks

Robson,

Haddad

2024

Sci Rep

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“…where I m f and I m b are the equivalent forward and backward modal current vectors, respectively. By substituting Equation 32into Equations (29) and (30), the voltage and current vectors are:…”

Section: Characteristic Impedance Matrices With Grounding Pointsmentioning

confidence: 99%

“…Similar issues have been studied for overhead lines when the shield wires are grounded at towers, and different treatments have been adopted. A typical approach involves assuming that the shield wires are continuously grounded and that the shield wires have zero potential along their entire length [25][26][27][28][29]. In previous studies [30][31][32], this assumption was proven to be unsuitable when the electrical length between towers is odd multiples of a one-half wavelength of signal.…”

Section: Introductionmentioning

confidence: 99%

Characteristic Impedance Analysis of Medium-Voltage Underground Cables with Grounded Shields and Armors for Power Line Communication

Zhao¹,

Zhang²,

Wang³

2019

Electronics

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The characteristic impedance of a power line is an important parameter in power line communication (PLC) technologies. This parameter is helpful for understanding power line impedance characteristics and achieving impedance matching. In this study, we focused on the characteristic impedance matrices (CIMs) of the medium-voltage (MV) cables. The calculation and characteristics of the CIMs were investigated with special consideration of the grounded shields and armors, which are often neglected in current research. The calculation results were validated through the experimental measurements. The results show that the MV underground cables with multiple grounding points have forward and backward CIMs, which are generally not equal unless the whole cable structure is longitudinally symmetrical. Then, the resonance phenomenon in the CIMs was analyzed. We found that the grounding of the shields and armors not only affected their own characteristic impedances but also those of the cores, and the resonance present in the CIMs should be of concern in the impedance matching of the PLC systems. Finally, the effects of the grounding resistances, cable lengths, grounding point numbers, and cable branch numbers on the CIMs of the MV underground cables were discussed through control experiments.

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