Studies to Utilize Loading Guides and ANN for Oil-Immersed Distribution Transformer Condition Monitoring
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Abstract:
There are plenty of proper monitoring methods to evaluate the condition and possible incipient failures of a power transformer. For distribution transformer monitoring, the methods are usually too expensive and/or time consuming to use. However, cost-efficient methods for distribution transformer monitoring are needed and one possibility for this is to utilize loading and temperature information measured from the network. The monitoring methods presented in the paper are based on the existing IEC and IEEE standards and neural-network analysis. The methods are used to calculate the top-oil and hot-spot temperature as well as the loss of life of a transformer. The calculated results are verified with measured top-oil temperature values. The possibilities to utilize studied methods in a larger scale for distribution transformer monitoring are also discussed in this paperKeywords:
Condition Monitoring
Energy efficient transformer
The distribution transformer is an important equipment in the distribution network,currently in the operation management of distribution transformer mainly exists problems such as difficult to timely access to the current state of information because of the location of distribution transformer scattered,;the distribution transformer overload long run;distribution transformer load variety can have great influence on the quality of distribution network power.Intelligent monitoring system of distribution transformer is mainly composed of distribution transformer monitoring terminal,communication network and the data center.Distribution transformer monitoring terminal is installed in transformer field,collected data by electrical parameters of voltage transformer and current transformer on both sides of the transformer,and then sent them to the GPRS module,the GPRS module the data through the GPRS network transmission to data center server.Measurement,metering,energy abnormal condition The terminal of distribution transformer mainly realize measurement of relative parameters,metering of electric energy,alarm of abnormal condition and,analysis and prediction of running status.
Energy efficient transformer
Metering mode
Tap changer
Delta-wye transformer
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The transformer is one of the main components in the power network and transformer windings are one of the most expensive elements in the power transformer. Optimisation of winding distances is one of the most important parameters during the manufacturing of transformer. The distance between the windings in the two winding transformers is well known to transformer designers and manufacturers. However, insulation of the high voltage transformer with additional winding and tap winding is still a major problem for transformer designers. In this study, the additional winding to tap winding distance optimisation is made for a high voltage power transformer. Optimisation of the transformer's windings just not minimises the cost of the transformer but also increases the lifetime of the transformer. With additional winding and tap winding in high-voltage transformers, insulation distance is a major concern for minimising the cost and size of the high voltage transformer. In this study, an approach is made to balance the cost, size, and safety of high voltage transformers. The optimised distance and position between tap winding and additional winding are determined by using the finite element analysis. The finite element method results were also verified by making a prototype transformer.
Delta-wye transformer
Energy efficient transformer
Autotransformer
Transformer effect
Tap changer
Transformer types
Leakage inductance
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Firstly, this paper introduces the development of new materials, new technology and new manufacture in power industry of China, energy-saving, low noise and smart distribution transformers are widely used in countryside power grid reconstruction. In this paper, application status and development trend of different types of distribution transformers were introduced and compared in terms of new material and new structure, such as oil-immersed distribution transformer, amorphous core transformer(AMT), dry-type transformer, SF6 insulated distribution transformer, composite transformer and other types of distribution transformers. The development of distribution transformer is mainly based on energy saving, miniaturization, wound core and amorphous alloy nowadays, but the class-H dry-type transformer and tridimensional toroidal-core amorphous alloy transformer are the future direction of development. The technology application of smart distribution grid, power electronics technology and dynamic reactive power compensation technique will also affect the safety and economic operation of distribution transformer.
Energy efficient transformer
Power grid
Delta-wye transformer
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The characteristics,operational reliability and advantages of amorphous alloy core transformer are introduced.The no-load loss of this type of distribution transformer is much lower than that of traditional distribution transformer.This kind of transformer is proposed to save more energy than traditional ones.
Energy efficient transformer
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The importance of distribution transformer no-load loss on the operation of modern electrical grids is often underestimated. Internationally, distribution transformer no-load loss constitutes nearly 25% of the transmission and distribution losses of electrical grids. The losses in European Union distribution transformers are estimated at about 33 TWh/year whereas, reactive power and harmonic losses add a further 5 TWh/year. In the Greek electrical grid the no-load losses of 140,000 distribution transformers are estimated at about 490 GWh/year. This paper has two goals the first one is to illustrate the significance of distribution transformer no-load loss in periods of high electric energy cost and the second goal is the presentation of a novel numerical methodology for wound core transformers no-load loss analysis, enabling to determine the economically and technically optimum transformer for every use.
Energy efficient transformer
Power grid
Electric power distribution
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Transformers are normally designed and built for use at rated frequency and sinusoidal load current. A non-linear load on a transformer leads to harmonic power losses which cause increased operational costs and additional heating in transformer parts. It leads to higher losses, early fatigue of insulation, premature failure and reduction of the useful life of the transformer. To prevent these problems, the rated capacity of transformer which supplies harmonic loads must be reduced. In this work a typical 50 KVA three phase distribution transformer with real practical parameters is taken under nonlinear loads generated due to domestic loads. The core losses is evaluated using the three dimensional model of the transformer developed in Ansoft Maxwell based on valid model of transformer under high harmonic conditions. And finally a relation associated with core losses and amplitude of high harmonic order are reviewed & analyzed and then a comparison is being carried out on the results obtained by different excitation current in transformer windings.
Energy efficient transformer
Delta-wye transformer
Transformer effect
Quadrature booster
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Power transformer is very important in electric power system due to its function to raise or lower the voltage according to its designation. On the power side, the power transformer serves to raise voltage to be transmitted to the transmission line. On the transmission side, the power transformer serves to distribute the voltage between the main substations or down to the distribution voltage. On the distribution side, the stresses are channeled to large customers or lowered to serve small and medium customers. As the power transformer is so importance, it is necessary to protect against disturbance, as well as routine and periodic maintenance, so that the power transformer can operate in accordance with the planned time. Some factors that affect the duration of the power transformer is the ambient temperature, transformer oil temperature, and the pattern of load. Load that exceeds the maximum efficiency of the transformer which is 80% of its capacity will cause an increase in transformer oil temperature. Transformer oil, other than as a cooling medium also serves as an insulator. Increasing the temperature of transformer oil will affect its ability as an isolator that is to isolate the parts that are held in the transformer, such as iron core and the coils. If this is prolonged and not handled properly, it will lead to failure / breakdown of insulation resulting in short circuit between parts so that the power transformer will be damaged. PLN data indicates that the power transformer is still burdened exceeding maximum efficiency especially operating in the work area of PLN South Bali Area. The results of this study, on distribution transformers with different loads, in DS 137, DS 263 and DS 363, show that DS 363 transformer with loading above 80% has the shortest residual life time compared to DS 263 and DS 137 which loading less than 80%.
Energy efficient transformer
Delta-wye transformer
Transformer effect
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THE ELECTRICAL PROPERTIES of deteriorated insulating oils can be restored by pumping the oil through alumina or activated clays. Some transformer operators use this method to clean up old oil and others process their transformer oil in this manner.
Thermosiphon
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Aiming at reducing the load loss of distribution transformer,new idea of developing energy-saving distribution transformer is brought out.The interior structure of new type distribution transformer is optimized,so the load loss is reduced obviously and the energy saving effect is significant.This technology provides a right energy saving approach for electric power user by reducing both no-load and load loss.Moreover,an alternative method is given for elimination of old type distribution transformer.
Energy efficient transformer
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The traditional high-voltage high-frequency transformer has a drawback of low power density owing to the rigorous requirements of high-voltage insulation. This study proposes a new configuration for the magnetic core based on planar EE cores. The parallel connection of planar cores was adopted as a unit, and several units were cascaded to form the high-voltage transformer. The electrical potential distribution of the proposed transformer is more uniform than a traditional transformer, and enables a decrease in the insulation distances. The mechanical configuration of a laboratory prototype is discussed, as well as the electrical, parasitic and thermal behaviours. A prototype transformer has been designed and built with the following characteristics: 30 kV output voltage, 60 kW output power and 20 kHz inverting frequency. The transformer was tested and found to have an efficiency of better than 96%. Compared with traditional high-voltage transformers, this transformer has good thermal behaviour, good line insulation properties and a high power density.
Energy efficient transformer
Delta-wye transformer
High Voltage
Transformer types
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