Diagnostic Measurements for Power Transformers

Tenbohlen, Stefan; Coenen, Sebastian; Djamali, Mohammad; Müller, Andréas; Samimi, Mohammad Hamed; Siegel, Martin A.

doi:10.3390/en9050347

Cited by 147 publications

(115 citation statements)

References 35 publications

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“…In the present work, the converter has been experimentally tested including the high-voltage transformer too [39][40][41], Figure 5. The results obtained allow a good operation of the converter to be verified, as shown in Figure 20.…”

Section: High-voltage Testmentioning

confidence: 99%

A Digitally Controlled Power Converter for an Electrostatic Precipitator

et al. 2017

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Electrostatic precipitators (ESPs) are devices used in industry to eliminate polluting particles in gases. In order to supply them, an interface must be included between the three-phase main line and the required high DC voltage of tens of kilovolts. This paper describes an 80-kW power supply for such an application. Its structure is based on the series parallel resonant converter with a capacitor as output filter (PRC-LCC), which can adequately cope with the parasitic elements of the step-up transformer involved. The physical implementation of the prototype includes the use of silicon carbide-SiC-semiconductors, which provide better switching capabilities than their traditional silicon-Si-counterparts. As a result, a new control strategy results as a better alternative in which the resonant current is maintained in phase with the first harmonic of the inverter voltage. Although this operation mode imposes hard switching in one of the inverter legs, it minimizes the reactive energy that circulates through the resonant tank, the resonant current amplitude itself and the switching losses. Overall efficiency of the converter benefits from this. These ideas are supported mathematically using the steady state and dynamic models of the topology. They are confirmed with experimental measurements that include waveforms, Bode plots and thermal behavior. The experimental setup delivers 80 kW with an estimated efficiency of 98%.

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Section: High-voltage Testmentioning

confidence: 99%

A Digitally Controlled Power Converter for an Electrostatic Precipitator

et al. 2017

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“…Here, when the thermal stress only affects the decomposition of transformer oil at the source of heat not involving the solid insulation, the gases produced are mainly low molecular weight hydrocarbon gases, among which the characteristic gases are generally CH 4 and C 2 H 4 , and the sum of the two generally accounts for more than 80% of the total hydrocarbons. In this situation, acetylene is usually not generated due to overheating failures.…”

Section: Introductionmentioning

confidence: 99%

“…DGA is also a most important reference index in the model correction [4]. Here, the model correction is aimed at large oil-immersed power transformers, which all adopt oil-paper insulation structures, thus the electrical parts of the whole body are completely immersed in the transformer oil.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, both in China and around the world, DGA technology is believed as an important approach for preventive test of power equipment. For a normal oil-immersed power transformer, the content limits of hydrogen-containing gases and hydrocarbon gases in transformer oil are as follows: the normal limits [3] of H 2 , CH 4 , C 2 H 6 , C 2 H 4 , C 2 H 2 and total hydrocarbons are 150, 45, 35, 65, 5 and 150 ppm, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…In these tests, the parameters that can really reflect the ageing failure of the transformer are often used to correct the original ageing assessment model in order to maximize the reliability evaluation value close to the real value and reduce the accumulation error with the time to decommissioning [3]. In China, preventive tests have been an important part of electric power production practice for a long time, and has which played a positive role in the safe operation of the power equipment [4]. Also in China, the Southern China Power Grid Corporation has issued an enterprise standard named Preventive Test Procedures for Electric Power Equipment, in which the prescribed preventive tests of insulation items as presented in Table 1 are given.…”

Section: Introductionmentioning

confidence: 99%

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Dissolved Gas Analysis Principle-Based Intelligent Approaches to Fault Diagnosis and Decision Making for Large Oil-Immersed Power Transformers: A Survey

Cheng

2018

Energies

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Abstract:Compared with conventional methods of fault diagnosis for power transformers, which have defects such as imperfect encoding and too absolute encoding boundaries, this paper systematically discusses various intelligent approaches applied in fault diagnosis and decision making for large oil-immersed power transformers based on dissolved gas analysis (DGA), including expert system (EPS), artificial neural network (ANN), fuzzy theory, rough sets theory (RST), grey system theory (GST), swarm intelligence (SI) algorithms, data mining technology, machine learning (ML), and other intelligent diagnosis tools, and summarizes existing problems and solutions. From this survey, it is found that a single intelligent approach for fault diagnosis can only reflect operation status of the transformer in one particular aspect, causing various degrees of shortcomings that cannot be resolved effectively. Combined with the current research status in this field, the problems that must be addressed in DGA-based transformer fault diagnosis are identified, and the prospects for future development trends and research directions are outlined. This contribution presents a detailed and systematic survey on various intelligent approaches to faults diagnosing and decisions making of the power transformer, in which their merits and demerits are thoroughly investigated, as well as their improvement schemes and future development trends are proposed. Moreover, this paper concludes that a variety of intelligent algorithms should be combined for mutual complementation to form a hybrid fault diagnosis network, such that avoiding these algorithms falling into a local optimum. Moreover, it is necessary to improve the detection instruments so as to acquire reasonable characteristic gas data samples. The research summary, empirical generalization and analysis of predicament in this paper provide some thoughts and suggestions for the research of complex power grid in the new environment, as well as references and guidance for researchers to choose optimal approach to achieve DGA-based fault diagnosis and decision of the large oil-immersed power transformers in preventive electrical tests.

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