Zhumao Lu

Fault simulation and diagnostic test for abnormal voltage of secondary coil of capacitor voltage transformer

The transformer protection action is investigated and studied caused by over-excitation due of capacitor voltage transformer secondary coil voltage that is increased. In order to find the reasons of the transformer protection action, routine tests, diagnosis tests are conducted and theses data are accord with national standards. According to infield inspection, faults simulation and analysis method are proposed which results indicated that the protection action caused by electromagnetic interference of the secondary loop. In order that prevent the occurrence of similar failures, some suggestions for operation and maintenance of capacitor voltage transformers are concluded.

Fractal acoustic metamaterials for transformer noise reduction

Different from the early acoustic metamaterials, we draw on the application of the Hilbert curve in the radio frequency identification tag antenna, to make Hilbert fractal acoustic metamaterials (HFAMMs) with a self-similar fractal structure. This type of ventilated, sub-wavelength acoustic metamaterial has a relatively high reflection coefficient near the anti-resonance frequencies, resulting in high sound transmission loss (TL). The TL of the HFAMMs increases with the decrease in the waveguide width; similarly, the number of frequency bands of acoustic insulation increases and the frequency bands of sound insulation shift to low frequencies with the increase in the fractal order. The experimental results show that due to the viscothermal losses, the transmission coefficient at the resonant frequencies is greatly weakened, so that the HFAMM has broadband sound insulation performance. The TL of the third-order HFAMM can reach more than 30 dB at the main frequencies of the transformer noise. Furthermore, based on the method of selecting the optimal HFAMMs, we can easily design the HFAMMs suitable for the frequency bands of the noise need to be reduced; therefore, there is a broad application prospect in the field of noise reduction especially for low frequency noise. Different from the early acoustic metamaterials, we draw on the application of the Hilbert curve in the radio frequency identification tag antenna, to make Hilbert fractal acoustic metamaterials (HFAMMs) with a self-similar fractal structure. This type of ventilated, sub-wavelength acoustic metamaterial has a relatively high reflection coefficient near the anti-resonance frequencies, resulting in high sound transmission loss (TL). The TL of the HFAMMs increases with the decrease in the waveguide width; similarly, the number of frequency bands of acoustic insulation increases and the frequency bands of sound insulation shift to low frequencies with the increase in the fractal order. The experimental results show that due to the viscothermal losses, the transmission coefficient at the resonant frequencies is greatly weakened, so that the HFAMM has broadband sound insulation performance. The TL of the third-o...

Measurement and analysis of UHV transformer noise with sound intensity and vibration method

With the rapid increase of the substation grade, the number of ultra-high voltage (UHV) transformer is increasing and the noise caused by the vibration of UHV transformer is becoming more and more serious. The vibration of UHV transformer is mainly generated from the magnetostrictive effect of the iron core and the action of the electromagnetic force of the winding. In this paper, the sound intensity and the vibration of the 1000kV UHV transformer are measured and the frequency characteristic is analyzed in detail. The vibration acceleration distribution on the oil tank surface of the transformer is measured and analyzed. The results can provide data support for the transformer noise source identification and the noise suppression measures.

Noise analysis of UHV power transformer and research on active noise reduction system

With the rapid development of the power grid and the increase of power demand, the voltage level of the substation is improving rapidly. The noise caused by the transformer becomes a serious problem because it affects the health of the surrounding residents. In this paper, the noise of 1000kV transformer in Shanxi is measured and analyzed. The results show that the transformer noise has low frequency characteristics, and the frequency is mainly concentrated in 100Hz and its integer times. According to the transformer noise characteristics, an adaptive active noise reduction system is designed based on least mean square (LMS) adaptive filtering algorithm. The influence of filter step size factor and filter coefficient on the convergence and stability of LMS adaptive filtering algorithm is analyzed through simulation. The active noise reduction system is built and then the noise reduction experiment is carried out. Achieved about 6 dB noise reduction.

Research and Application Toward the Atlas Variation Detection Technology of Soft Sensor in Substation’s State Intelligence Analysis System

To improve the substation’s remote monitoring capability, this system adopts the computer technology, automation technology, and atlas processing and atlas recognition technology to analyze and compare massive monitoring data, so as to improve retrieval efficiency of the video, provide a new kind of monitoring way to monitor the substation’s environmental security situation, the abnormality of electrical equipment, automatic tracking of abnormal target and other monitoring requirements, and realize intelligent warning of the substation’s fault information.

The Application Research on Ultrasonic Partial Discharge Detection for Transformer

As an effective discharged detection technology, the ultrasonic partial discharge detection can discover the potential defects of power equipment in operation, which has been applied in the fault diagnosis to the GIS, transformer, cable connector and the high voltage switchgear, etc. But in the practical application, due to the problems such as interference exclusion, signal identification and positioning, it is difficult to the property and location of defect to make accurate judgments. In this paper, based on ultrasonic discharge test case for transformer with defects, the ultrasonic discharge diagnosis method of transformer defect are analyzed and summarized, and the characteristics of the transformer ultrasonic partial discharge is proposed.

Diagnosis and analysis for a typical defect of partial discharge in GIS

GIS equipment is widely used in electric power system, however, partial discharge affect the normal operation of the equipment. The paper introduces the principle of ultra-high frequency and acoustic emission partial discharge living detection methods and SF6 gas decomposition detection. And this pa per introduces typical defect cases of partial discharge in GIS equipment using different living detection method, combined with on-line monitoring. The living detection result is verified correctly after dismantlement, and analyses the reason of partial discharge. The final conclusion is that combined with ultra-high frequency on-line monitoring and a variety of living detection methods can improve the detection efficiency for insulation defects such as partial discharge in GIS equipment.