Analysis of Overvoltages on Power Transformer Recorded by Transient Overvoltage Monitoring System

Filipović-Grčić, Božidar; Jurišić, Bruno; Keitoue, Samir; Murat, Ivan; Filipović-Grčić, Dalibor; Župan, Alan

doi:10.1007/978-981-15-5600-5_8

Cited by 5 publications

(6 citation statements)

References 14 publications

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“…An example of EMTP simulation of a lightning strike to a 220 kV overhead line tower, which led to flashover in phase B, following by the flashover in phase A, is given below. Observed transformer unit is located in the area with significant lightning activity and high soil resistivity due to the rocky mountain terrain [11]. Seven 110 kV and two double-circuit 220 kV overhead lines are connected to the substation with three autotransformer 220 kV/110 kV working in parallel.…”

Section: Emtp Simulation Inlcuding High Frequency Transformer Modellingmentioning

confidence: 99%

“…Overhead lines, busbars and connections inside substation are modelled using frequency dependent line models [12]. Surge arresters are installed in every transformer bay (surge arresters with rated voltage U r =198 kV are installed at 220 kV level and with U r =108 kV at 110 kV level) [11] Once the model is established, it can be used in EMTP to simulate overvoltages [10]. An example of EMTP simulation of a lightning strike to a 220 kV overhead line tower, which led to flashover in phase B, following by the flashover in phase A, is given below.…”

Section: Emtp Simulation Inlcuding High Frequency Transformer Modellingmentioning

confidence: 99%

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Integral Approach for Overvoltage Management Based on Field Data and Modelling

Jurišić¹,

Župan²,

Filipović-Grčić³

et al. 2023

joe

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The requirements for the power network to be flexible and to be able to transmit more power are becoming more important as a consequence of high share of the renewables. Therefore, to maintain the level of reliability of the power network, it is necessary to monitor more and more data as well as to better understand the phenomena that might exist in the power system, such as transients. One of the points that are of interest are interaction between power transformer and the other components in the network. A failure of such component may lead to power network unavailability and high economic cost. According to the CIGRE WG A2.37, high portion of the transformer failure may have been caused by the overvoltage. Therefore, it is important to handle overvoltage in the power network with high care. In this paper, an integral approach for power transformer overvoltages management based on field measurements and advanced electromagnetic transients (EMT) modelling is presented. It consists of simulating overvoltages using detailed power network models, including the high frequency transformer models and continuous monitoring of overvoltage events at the places of interest in the power network. This work gives a framework for dealing with overvoltages in the power network that could be implemented by power utilities.

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Section: Emtp Simulation Inlcuding High Frequency Transformer Modellingmentioning

confidence: 99%

Section: Emtp Simulation Inlcuding High Frequency Transformer Modellingmentioning

confidence: 99%

Integral Approach for Overvoltage Management Based on Field Data and Modelling

Jurišić¹,

Župan²,

Filipović-Grčić³

et al. 2023

joe

View full text Add to dashboard Cite

show abstract

“…As the transformer unit is situated in the area with high ground flash density, all three overvoltages were caused by the lightning strikes. In the case 1, double phase to ground fault occurs in the phases U and W as shown in Figure 7 (a) [7]. For further analysis of the impulse signal or usage of the signal in EMTP simulations, it is necessary to filter the impulse from the 50 Hz data.…”

Section: Verification Of System In High Voltage Laboratorymentioning

confidence: 99%

“…Case 2 represents a double-phase to ground short-circuit on transmission line while case 3 remained without the fault. It is important to note that the overvoltages observed in the power network differ from the standard 1.2/50 µs impulse as they have oscillatory behavior and dominant frequency components in the range from 1 to 30 kHz [7].…”

Section: Verification Of System In High Voltage Laboratorymentioning

confidence: 99%

Fleet Asset Management Opportunities Arising from Transient Monitoring of Power Transformers and Shunt Reactors

Župan¹,

Jurišić²,

Murat³

et al. 2020

joe

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Power transformers and shunt reactors are strategic assets for every system operator and their downtime should be kept as low and controlled as possible. During their multi-decade service life, they are regularly exposed to transient overvoltages. These situations stress their insulation systems and can cause accelerated deterioration and aging. Since the shapes of these overvoltages are usually unknown, an additional approach to assessing the health index can be realized using monitoring systems with transient recorders. Analyzing the transient overvoltages using frequency domain severity factor, a quantification of additional stress on the transformer’s/shunt reactor’s insulation can be given. This can help in assessing the current state of the insulation system and can lead to more advanced fleet asset management.

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“…However, this method has not completely solved the problems related to overvoltage protection. Many transformers have been damaged as a result of overvoltage stress, despite the fact that the transformers passed the normalized voltage tests with a positive result and were protected against overvoltages with the use of surge arresters [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Overvoltage Impact on Internal Insulation Systems of Transformers in Electrical Networks with Vacuum Circuit Breakers

et al. 2020

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Vacuum circuit breakers are increasingly used as switching apparatus in electric power systems. The vacuum circuit breakers (VCBs) have very good operating properties. VCBs are characterized by specific physical phenomena that affect overvoltage exposure of the insulation systems of other devices. The most important phenomena are the ability to chop the current before the natural zero crossing, the ability to switch off high-frequency currents, and the rapid increase in dielectric strength recovery. One of the devices connected directly to vacuum circuit breakers is the distribution transformer. Overvoltages generated in electrical systems during switching off the transformers are a source of internal overvoltages in the windings. The analysis of the exposure of transformers operating in electrical networks equipped with vacuum circuit breakers is of great importance because of the impact on the insulation systems of switching overvoltages (SO). These types of overvoltages can be characterized by high maximum values and atypical waveforms, depending on the phenomena in the circuit breaker chambers, system configuration, parameters of electrical devices, and overvoltage protection. Overvoltages that stress the internal insulation systems are the result of the windings response to overvoltages at transformer terminals. This article presents an analysis of overvoltages that stress the transformer insulation systems, which occur while switching off transformers in systems with vacuum circuit breakers. The analysis was based on the results of laboratory measurements of switching overvoltages at transformer terminals and inside the winding, in a model medium-voltage electrical network with a vacuum circuit breaker.

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Analysis of Overvoltages on Power Transformer Recorded by Transient Overvoltage Monitoring System

Cited by 5 publications

References 14 publications

Integral Approach for Overvoltage Management Based on Field Data and Modelling

Integral Approach for Overvoltage Management Based on Field Data and Modelling

Fleet Asset Management Opportunities Arising from Transient Monitoring of Power Transformers and Shunt Reactors

Overvoltage Impact on Internal Insulation Systems of Transformers in Electrical Networks with Vacuum Circuit Breakers

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