Examination on the Denoising Methods for Electrical and Acoustic Emission Partial Discharge Signals in Oil

Partial discharge (PD) measurements either through electrical or acoustic emission approaches can be subjected to noises that arise from different sources. In this study, the examination on the denoising methods for electrical and acoustic emission PD signal is carried out. The PD was produced through needle-plane electrodes configuration. Once the voltage reached to 30 kV, the electrical and acoustic emission PD signals were recorded and additive white Gaussian noise (AWGN) was introduced. These signals were then denoised using moving average (MA), finite impulse response (FIR) low/high-pass filters, and discrete wavelet transform (DWT) methods. The denoising methods were evaluated through ratio to noise level (RNL), normalized root mean square error (NRMSE) and normalized correlation coefficient (NCC). In addition, the computation times for all denoising methods were also recorded. Based on RNL, NRMSE and NCC indexes, the performances of the denoising methods were analyzed through normalization based on the coefficient of variation (). Based on the current study, it is found that DWT performs well to denoise the electrical PD signal based on the RNL and NRMSE index while MA has a good denoising NCC and computation time index for acoustic emission PD signal

Investigation of Static Voltage Accumulation on Wind Turbine Blade in Atmospheric Wind speed Humidity and Temperature

Wind turbines are one of renewable energy sources. Wind turbines installed at wild open area such offshore, mountains and deserts are filled with air particles and flow of wind speed. During the wind flow throughout the wind turbines which rotates the turbine blades, there is friction between the air particles and the blade surface that leads the static voltage to accumulate on the blade surface causing upward streamers. Using fiberglass reinforced plastic (FRP) wind turbine blades by simulation and experimental method. The charged particle tracing with electrostatics and laminar flow with time-dependent used to determine the value of static voltage accumulation. Static voltage accumulation is influenced by various factors such as wind speed (1, 5, and 7 m/s), humidity (20, 50, and 70 %RH) and temperature (28, 35, and 48 oC) had tested and analyzed. Furthermore, the result obtained using the Finite Element Method (FEM) has shown a good agreement with the experimental result. It was observed that high flow velocity has a great tendency to charge the blade surface with 36.70%higher from 1 m/s to 7 m/s. Low relative air humidity increases the risk of static electricity 221.6 V at the of side of the blade when humidity is 20%. Moreover, increasing the air temperature from 28 to 48 degrees Celsius increases the voltage by 20%. Therefore, determining the need for statice voltages generated in the blade surface and the risk related to upward streamers is obliged to be evaluated as it is the essential ways in adopting the correct protection systems

Effect of silica nanofiller in cross-linked polyethylene as electrical tree growth inhibitor

One of the main phenomena that contributes to the non-success of cable insulation made of cross-linked polyethylene (XLPE) is electrical treeing. To improve the XPLE cable insulation, the use of nanofiller has been introduced. Adding the nanofiller in the based composite offers better cable lifetime and resistance to deal with the cable failure. One of the potential nanofillers that can increase the insulation performance of XLPE cable is silica nanofiller. To this extent, the studies on silica nanofiller in XLPE are focusing on the impulse breakdown strength, dielectric loss, permittivity, space charge, alternating current (AC), and partial discharge. The studies reveal that the dielectric properties of the XLPE nanocomposite have significant improvement. Therefore, this work investigates the effect of various concentrations of silica nanofiller in XLPE composite as electrical tree inhibitor. The concentrations of silica nanofiller in XLPE were 0.25 wt%, 0.5 wt%, 0.75 wt%, 1.0 wt%, 1.25 wt%, 1.5 wt%, and 1.75 wt%. The silica nanofillers have 96%-99% purity, 20-30 nm sizes and the shapes are spherical. As a result, the XLPE composite containing 1.5 wt% silica nanofiller demonstrate higher tree inception voltage and detaining the tree propagation speed, which could be considered as an inhibitor medium of electrical tree growt

診断技術開発の基礎としての環境調和型ガス絶縁媒体の部分放電特性および分解ガス分析の研究

九州工業大学博士学位論文 学位記番号: 工博甲第260号 学位授与年月日: 平成20年3月25日Chapter 1 Introduction|Chapter 2 Experimental setup and method|Chapter 3 Discharge properties and emitted electromagnetic wave spectrum in low vacuum region of vacuum interrupter|Chapter 4 Partial discharge properties and determination of gas pressure in vacuum interrupter based on partial discharge|Chapter 5 AC sparkover voltage properties and gas decomposition by-product analysis of CF3I under non-uniform electric field| configuration|Chapter 6 Summary|Appendix|Acknowledgment|List of publications九州工業大学平成19年

診断技術開発の基礎としての環境調和型ガス絶縁媒体の部分放電特性及び分解ガス分析の研究

九州工業大学博士学位論文（要旨） 学位記番号:工博甲第260号 学位授与年月日:平成20年3月25

診断技術開発の基礎としての環境調和型ガス絶縁媒体の部分放電特性および分解ガス分析の研究

九州工業大学博士学位論文 学位記番号:工博甲第260号 学位授与年月日:平成20年3月25日Chapter 1 Introduction|| Chapter 2 Experimental setup and method|| Chapter 3 Discharge properties and emitted electromagnetic wave spectrum in low vacuum region of vacuum interrupter|| Chapter 4 Partial discharge properties and determination of gas pressure in vacuum interrupter based on partial discharge|| Chapter 5 AC sparkover voltage properties and gas decomposition by-product analysis of CF3I under non-uniform electric field|| configuration Chapter 6 Summary|| Appendix|| Acknowledgment|| List of publication

A comprehensive analytical subdomain model and its field solutions for surface-mounted permanent magnet machines

This paper presents a comprehensive analytical subdomain model together with its field solutions for predicting the magnetic field distributions in surface-mounted permanent magnet (PM) machines. The tooth tips and slotting effects during open-circuit, armature reaction, and on-load conditions are considered when deriving the model and developing its solutions. The model derivations and field solutions are extended from a previous model, and can be applied to PM machines with any combinations of slot and pole numbers and any magnetization patterns in the magnets. This model is initially formulated according to Laplace\u27s and Poisson\u27s equations in 2-D polar coordinates by the separation of variables technique in four subdomains, such as magnet, airgap, winding slots, and slot-openings. The field solution of each subdomain is obtained applying the appropriate boundary conditions and interface conditions between every two subdomains, respectively, which can precisely account for the mutual influence between slots. Finite element analysis (FEA) is later deployed to validate the analytical results in a surface-mounted PM machine that has nonoverlapping winding arrangement. For validation purposes, PM machines having 3-slot/2-pole with parallel magnetization and 12-slot/10-pole with either parallel or radial magnetizations are used for comparisons. Computation of global quantities for the motor which include the phase back-EMF and cogging torque is also included. The results indicate that the proposed analytical model can accurately predict the magnetic field distributions in each subdomain and the motor\u27s global quantities, which are in good agreement with those obtained from the FEA