Papers by Keyword: Transformer

Abstract: The key issue for the oil filter product sand operating status of the transformer oil filter, and in-depth research, based on the research and development of the transformer oil filtering device charged. Charged transformer oil filtering device structure includes an external oil circulation system, internal purification systems and automatic control and protection system of three parts. The device has also explained the conventional oil filter and oil filter charged two modes, when conventional oil filter modes election, workflow is identical with ordinary oil filter; If you choose to live oil filtering mode, you need to set the control variable range and start monitoring and adjustment, transformer oil filtering method has been put live field application, its efficiency and reliability of the actual verification.

Abstract: Low voltage current transformers are widely used in power system. Such as the records of power consumption, energy trading and industrial load monitoring, is an important measuring component in electric power system of China at the present stage. Whether the low voltage current transformer is accurate or not, related to the power customer's vital interests and the power grid enterprise`s economic benefits, also affects the quality of grid service level and the fulfillment of social responsibilities. To establish a quality assurance system, make the fault detection rate and the percent of pass of the automatic verification system is accordance with the requirements. At the same time, the establishment of online diagnosis system can remind the staff when any failure occurs and help them repairs the fault as soon as possible. It can provide a strong guarantee for the stable operation, management and protection of the automatic verification system.

Abstract: This paper is concerned with the study of the performance of soft magnetic ferrite mixed with aluminum cement and silicon steel sheet. By measuring the amount of different substitution, the mix proportion of the soft magnetic ferrite, the temperature of different experimental point on the transformer, and the output voltage, we can analysis the performance of soft ferrite on permeability, loss rate and so on. After the data was analyzed, we can get the best mix proportion of iron aluminum and cement,and the best amount of substitution replacing silicon steel sheet.Then a new type of mix soft magnetic ferrite is developed. This experimental study can be applied to large-scale power and electrical equipment which can reduce production costs and improve production efficiency.

Abstract: Transformer is the main equipment of power system, its operation reliability is directly related to power system security and reliability of power supply. In order to guarantee the safe operation of power system, must strengthen the monitoring of the main transformer.With the development and popularization of intelligent station, the detection of transformers insulation is faced with the new problem that PT signal is not convenient to get and even unable to get. This paper proposes the relative method which is used to calculate and monitor dielectric loss of transformer bushing and designs the on-line monitoring device, through the data acquiring form the on-line monitoring instrument which are installed in the transformer of substation shows that this method has high precision, strong anti-interference ability.

Abstract: When the HVDC works in mono-polar operation or bipolar unbalanced operation, DC flows through the neutral point and causes DC bias magnetic of transformer around HVDC grounding electrode, which influences the operation security of transformers. Beside highly saturated core, it also causes the distortion of exciting current, increasing harmonics and leakage magnetic flux, and thus the losses, which in turn results in the structures of transformer overheating and insulation aging. Based on the principle of transformer DC bias magnetic and UMEC of transformer in PSCAD/EMTDC, electromagnetic transient simulation platform of transformer DC bias magnetic is built. Considering the effect of DC bias magnetic on different structure of transformer, three kinds of typical transformer that has been widely applied are selected including three-phase three-limb transformer, three-phase five-limb transformer, three-phase bank transformer. After comparing the differences between these three kinds of transformer, related parameters are set such as the core structure and mode of winding connection and so on.

Abstract: Based on the large number of experimental data analysis and processing, a new inter-turn short circuit transformer diagnostic methods is proposed. In this paper, take the grounding current of transformer core as the signal source. Using wavelet multi-resolution technology the signal wavelet multiscale decomposition, we can get high frequency components of the signal. Achieve short-circuit fault diagnosis between transformer winding turns by comparing the number of the high-frequency component contained in different signals in the decomposition of the same scale.

Abstract: This paper describes the harmonic current effect under static and dynamic load on 3 phase 100kVA transformer model. The methodology that used to measure a harmonic current is using power analyzer with different excitation. The experiment is conducted by changing input voltage with different flux density. A waveform can be obtained by using the data collected. 3^rd order of harmonic gives a high impact to the complex waveform. At 0.6 Tesla, 50 Hz, the 3^rd order of harmonic current under static load and dynamic load is 0.00196A and 0.26746A respectively. Therefore, both static and dynamic load were give an effect to harmonic current effect on transformer. This is because when the transformer connected to the load, more current and voltage induced in order to energize the load. Moreover, the loads itself have their own harmonic effect because of the functional mechanism.

Abstract: This paper describes the harmonic current effect at T-joint and corner joint on 3 phase 100kVA transformer model. The methodology that used to measure a harmonic current is using search coil connected to oscilloscope. The experiment is conducted by changing input voltage with different flux density. From the results obtained, the 3^rd order harmonic current shows the highest for both T – joint and corner joint. The highest harmonic occurred at T – joint. For in plane, the harmonic current is 0.237A at corner joint and 0.389A at T - joint. At normal condition, the harmonic current were 0.250A and 0.769A at corner joint and T – joint respectively. This happened because of more energy required for transferring the flux to the left and right of the core. The corner joint of harmonic is less since the flux direction is 90° thus smaller amount of energy is required for the movement.

Abstract: Most high-voltage faults are caused by the insulation degradation of electrical equipment, while partial discharge is the main reason of insulation breakdown of electrical equipment. This paper introduces partial discharge types of GIS, transformer, switchgear and other substation equipment based on the study of partial discharge types and summarizes five types of partial discharge of substation equipment, namely: spike discharge, free particle discharge, insulation defects discharge, surface discharge and suspended click discharge.

Abstract: Recently the wind power was customized to offshore due to more abundant wind than onshore. Transformer is a multi-terminal electrical device that transforms electrical energy and is filled with insulating oil. This study presents the feasibility of diglycerol ester as insulating oil for offshore wind turbine transformers. The sulfated zirconia (SZ) was prepared by the sol-gel method for use on synthesize of diglycerol ester. The diglycerol ester was synthesized with diglycerol and fatty acids over SZ for use on insulating oil of offshore wind turbine transformer. The SZ600 has the highest conversion of fatty acids. The insulation properties of synthesized diglycerol ester over SZ600 shows that the pour point is-50°C and the flash point is 316°C. Therefore, it is suitable for diglycerol ester over SZ600 to be used in offshore wind turbine transformer.