Impact of First Tower Earthing Resistance on Fast Front Back-Flashover in a 66 kV Transmission System

Moselhy, Abdullah H.; Abdel-Aziz, Abdelaziz M.; Gilany, Mahmoud; Emam, Ahmed

doi:10.3390/en13184663

Cited by 5 publications

(3 citation statements)

References 30 publications

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“…When calculating lightning surges arising on overhead power lines, the question often arises: how many towers should be taken into account? According to a review of publications [15] on this topic, it is necessary to take into account from 4 to 7 power transmission towers. To clarify the answer to this question using digitized oscillograms of real lightning currents, studies were carried out, the results of which are shown in Table 1.…”

Section: Research Results and Discussionmentioning

confidence: 99%

Estimation of voltage waveform at top of transmission line tower struck by lightning of negative and positive polarity

Trotsenko

Dixit²,

Brzhezitsky

2021

TAPR

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The object of research is a circuit that simulates a lightning strike to a tower of 220 kV power transmission line, taking into consideration the reflection of a current wave from 10 nearest towers. Computation of the voltage arising at the top of the struck tower is necessary further to determine the lightning performance of transmission line by various methods. The lightning current has several maxima, in the case of a positive impulse polarity and, accordingly, several minima, in the case of a negative polarity, which are generally being called peaks. In addition, the lightning current impulse has a non-constant steepness in the entire area of current rise up to the first peak. The approximation of the real lightning current by simplified mathematical expressions cannot take into account all its real features. For a more detailed study of transient processes caused by thunderstorm activity, there is a need to use oscillograms of real lightning currents when modeling. The problem of determining the voltage at the top of the stricken transmission line tower was solved using circuit simulation. For an in-depth study of how the shape of the lightning current impulse affects the shape of the voltage at the top of the tower struck, digitized oscillograms of real lightning currents were used. The simulation was carried out for 7 negative lightning impulses with the first peak varying from –33.380 kA to –74.188 kA. In the case of positive lightning, 3 oscillograms were used with the first peak varying from +38.461 kA to +41.012 kA. The article shows that the shape of the front of the lightning current impulse and the amplitude of the first peak of the lightning current have a decisive effect on the maximum voltage value at the top of a power transmission line tower struck by lightning. The maximum voltage occurs precisely at the front of the current wave before the first peak of the lightning current. Therefore, the back flashover of the insulation from the tower to the phase conductor is most likely at a moment in time at the front of the current wave. By the time the maximum current is reached, the voltage at the top of the tower will be reduced by several tens of percent, compared to the maximum voltage at the tower, which occurs much earlier at the front of the current wave. The conducted research contributes to the development of methods for calculating the lightning performance of power lines and extends the scope of application of circuit simulation programs.

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Section: Research Results and Discussionmentioning

confidence: 99%

Estimation of voltage waveform at top of transmission line tower struck by lightning of negative and positive polarity

Trotsenko

Dixit²,

Brzhezitsky

2021

TAPR

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“…EMTP can be projected to analyze transients on circuits containing concentrated parameters (R, L, and C), transmission lines with distributed parameters, and line with no transposition. Phase conductors and shielding cables are modeled based on tower data [26], [38]- [41]. A brief outline of the EMTP-ATP model used purposely for this paper is presented in the form of a model consisting of several components [42]- [45]: i) generator, ii) phase conductors of transmission lines and shielding cables including line termination and power frequency voltage, iii) transmission line tower, iv) tower grounding impedance, v) string insulator (i.e.…”

Section: Transient Program (Emtp)mentioning

confidence: 99%

Proposal of analysis method to reduce back-flashover rate taking account of tower footing resistance

Warmi

Zulkarnaini²,

Rajab³

et al. 2023

IJECE

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<span lang="EN-US">The number of lightning stroke on the tower of the 150 kV Koto Panjang-Payakumbuh transmission line located the rocky area has been observed. The high value of tower footing resistance indicates the occurrence of the back-flashover in the transmission line at intensity of 74%. The back-flashover occurrence is dominantly triggered by the tower footing resistance value. Also, the rate of back-flashover has an effect on the value of the tower footing resistance by considering the number of electrode installations. A design is proposed for the grounding system of the tower footings in order to reduce the rate of back-flashover. The results presenting in numerical simulation indicates that it works properly after adding 4 electrodes. That is to say, installing 4 electrodes in each tower has successfully decreased the tower footing resistance value, back-flashovers rate 80% and 90-95% of present value respectively. The insulator voltage can be reduced to less than half of the present voltages as much as 30-50%. In more detail, in tower 77, the value of the tower footing resistance drops to 2.84 Ω, the flashover rate drops to 0.57/100 km/year and the insulator voltage drops to 0.99 MV when a disturbance occurs.</span>

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“…The grounding grid is an important component for lightning protection [1,2]. The transient performance of grounding system has been a hot topic for a long time [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Transient Performance of Grounding Grid with Lightning Rod Installed on Multi-Grounded Frame

2021

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In large substations, many lightning rods are installed on multi-grounded frames. The lightning rods, the frame, the grounding grid and the soil form a whole body, and the lightning current will be discharged from many grounding points. In this paper, based on the partial element equivalent circuit method, a numerical model, in the time domain, is developed to simulate the lightning-caused electromagnetic transients on the frame and the grounding grid. The model is verified by field testing and by comparison with commercial software. The model has several features: (1) it has a simple time domain form; (2) it is stable due to a staggered arrangement of space and time variables and an implicit difference scheme used, and (3) the dimension of the equations is relatively small because the unknown variables are divided into several groups, which are calculated one by one. With this method, the transient characteristics of the grounding grid with lightning rods on the frame are calculated, and the factors affecting the results are analyzed. It can be seen that although the frame causes the ground potential rise in an evenly distributed manner, compared with the situation in which the lightning strikes an independent lightning rod, the ground potential decrease rate near the main grounding point is almost the same because most of the current still enters the soil from the grounding electrode closest to the lightning strike. Therefore, even if there is a frame, the nearby facilities should take the same protective measures as in the case of an independent lightning rod. The ground conductors near the grounding points of the frame should be dense enough to reduce the potential gradient. The equipment should be kept at least 10 m away from the grounding point for lightning.

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Impact of First Tower Earthing Resistance on Fast Front Back-Flashover in a 66 kV Transmission System

Cited by 5 publications

References 30 publications

Estimation of voltage waveform at top of transmission line tower struck by lightning of negative and positive polarity

Estimation of voltage waveform at top of transmission line tower struck by lightning of negative and positive polarity

Proposal of analysis method to reduce back-flashover rate taking account of tower footing resistance

Numerical Analysis of Transient Performance of Grounding Grid with Lightning Rod Installed on Multi-Grounded Frame

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