Izoliacija ir viršįtampiai

Baublys, Juozas; Jankauskas, Pranas; Markevicius, L. A.; Morkvenas, Alfonsas

doi:10.5755/e01.9786090200346

Cited by 4 publications

(13 citation statements)

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“…After the main lightning surge repeated surge impulses mostly forms after 0.03 -0.05 sec, with their own suddenly settled leaders. We can count from 2 -3 till 10, very rare -even more repeated surge impulses during 1 second [1]. During experimental recordings full event was registered from the first lightning surge overvoltage till the power line disconnection.…”

Section: Surgementioning

confidence: 96%

Experimental Research of the Overvoltage in the Insulated Neutral Network

Gvozdas¹,

Valatka²

2010

Scientific Journal of Riga Technical University. Power and Electrical Engineering

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Abstract:The isolated neutral network isolation resistance is often affected by the lightning discharge surge to the line cables or towers. Several overvoltage waves are maid at the moment of the lightning discharge surge. It is dangerous for the devices because at the very short time period the isolation of the device is affected by the surge impact twice or even more. The analysis of the experimentally registered lightning discharge induced overvoltage transients effect from the lightning influence to the power line till the power line disconnection were analyzed in this work. Estimation of the overvoltage characteristics to the isolation resistance was made.

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Section: Surgementioning

confidence: 96%

Experimental Research of the Overvoltage in the Insulated Neutral Network

Gvozdas¹,

Valatka²

2010

Scientific Journal of Riga Technical University. Power and Electrical Engineering

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“…The theory of commutation transients can be found in [41,42]. The connection of an RLC series circuit to a voltage source E(t) is described by the second-order nonhomogeneous differential equation:…”

Section: Commutation Transientsmentioning

confidence: 99%

“…The positive strokes' current is typically higher, and its preferred limit for lightning protection is 200 kA. In nature, a 200 kA stroke occurs rarely-approximately 1% of all cases [42,47]. The selection of both the model and its parameters depends on the purpose: for example, for lightning protection design, parameters are selected with a margin.…”

Section: Atmospheric Transientsmentioning

confidence: 99%

IIR Shelving Filter, Support Vector Machine and k-Nearest Neighbors Algorithm Application for Voltage Transients and Short-Duration RMS Variations Analysis

Liubčuk,

Kairaitis,

Radziukynas

et al. 2024

Inventions

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This paper focuses on both voltage transients and short-duration RMS variations, and presents a unique and heterogeneous approach to their assessment by applying AI tools. The database consists of both real (obtained from Lithuanian PQ monitoring campaigns) and synthetic data (obtained from the simulation and literature review). Firstly, this paper investigates the fundamental grid component and its harmonics filtering with an IIR shelving filter. Secondly, in a key part, both SVM and KNN are used to classify PQ events by their primary cause in the voltage–duration plane as well as by the type of short circuit in the three-dimensional voltage space. Thirdly, since it seemed to be difficult to interpret the results in the three-dimensional space, the new method, based on Clarke transformation, is developed to convert it to two-dimensional space. The method shows an outstanding performance by avoiding the loss of important information. In addition, a geometric analysis of the fault voltage in both two-dimensional and three-dimensional spaces revealed certain geometric patterns that are undoubtedly important for PQ classification. Finally, based on the results of a PQ monitoring campaign in the Lithuanian distribution grid, this paper presents a unique discussion regarding PQ assessment gaps that need to be solved in anticipation of a great leap forward and refers them to PQ legislation.

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“…Let us begin with lightning events (Figure 71), which are among the six most common groups in the 10 kV grid (see Figure 69). The available division of the territory of Lithuania into lightning zones regarding annual thunderstorm duration can be found in [5,66]. This kind of analysis is beneficial for the field of lightning security (including the shielding of both substations and buildings), lightning arrester placement strategies, calculations of induced voltage in overhead power lines (including exceeding safe touch voltage).…”

Section: Case Studies Of Two-dimensional Probabilistic Analysismentioning

confidence: 99%

“…The cumulative distribution function of negative first stroke current can be found in [67]: a crest current up to 200 kA is expected. Usually, the first stroke is followed by 2-10 successive strokes with 0.03-0.05 s intervals between them [66]. When the cumulative distribution function is known, the probability density function is obtained as follows:…”

Section: Case Studies Of Two-dimensional Probabilistic Analysismentioning

confidence: 99%

Power Quality Monitors Displacement Based on Voltage Sags Propagation Mechanism and Grid Reliability Indexes

Liubčuk,

Radziukynas,

Kairaitis

et al. 2023

Applied Sciences

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Nowadays, voltage sag continues to remain a critical PQ issue in the industry. Since it is not possible to install a voltage analyzer on every node, optimal monitoring locations must be determined. However, during the PQ monitoring campaign of the Lithuanian DSO grid, the execution of this task was inhibited by the lack of knowledge and literature about the fundamentals of voltage sags propagation. Therefore, the first part of this paper investigates the propagation paths of voltage sags by using a voltage sag matrix method on the created test grid, which for the first time is BRELL-based. This paper is the first to not only investigate voltage sags propagation paths (both downward and upward) in detail, but also to investigate them complexly, encompassing all four types of short-circuits, both voltages (phase-to-phase and phase-to-ground), and interconnections with other PQ events (interruption, transient, unbalance). The result has established a generalization of voltage sags propagation mechanisms by inductive reasoning and laid the foundation for the further development of PQ theory. The second part of this paper focuses on the Lithuanian DSO grid and is one of the first to investigate voltage sags/interruptions through the prism of both relationship with reliability indexes (SAIFI and SAIDI) and primary causes. For this purpose, we created our own scientific methodology, applying known probabilistic and statistical methods along with newly proposed approaches, in particular for ACR success evaluation and estimation of functions similarity.

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Izoliacija ir viršįtampiai

Cited by 4 publications

References 0 publications

Experimental Research of the Overvoltage in the Insulated Neutral Network

Experimental Research of the Overvoltage in the Insulated Neutral Network

IIR Shelving Filter, Support Vector Machine and k-Nearest Neighbors Algorithm Application for Voltage Transients and Short-Duration RMS Variations Analysis

Power Quality Monitors Displacement Based on Voltage Sags Propagation Mechanism and Grid Reliability Indexes

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