Fuzzy Logic Approach to Dissolved Gas Analysis for Power Transformer Failure Index and Fault Identification

This research focuses on problem identification due to faults in power transformers during operation by using dissolved gas analysis such as key gas, IEC ratio, Duval triangle techniques, and fuzzy logic approaches. Then, the condition of the power transformer is evaluated in terms of the percentage of failure index and internal fault determination. Fuzzy logic with the key gas approach was used to calculate the failure index and identify problems inside the power transformer. At the same time, the IEC three-gas ratio and Duval triangle are subsequently applied to confirm the problems in different failure types covering all possibilities inside the power transformer. After that, the fuzzy logic system was applied and validated with DGA results of 244 transformers as reference cases with satisfactory accuracy. Two transformers were evaluated and practically confirmed by the investigation results of an un-tanked power transformer. Finally, the DGA results of a total of 224 transformers were further evaluated by the fuzzy logic system. This fuzzy logic is a smart, accurate tool for automatically identifying faults occurring within transformers. Finally, the recommendation of maintenance strategy and time interval is proposed for effective planning to minimize the catastrophic damage, which could occur with the power transformer and its network

วงจรจำลองค่าความต้านทานแบบลบที่ผันแปรตามความถี่โดยใช้ CDTRA และการประยุกต์ใช้งานในวงจรกำเนิดสัญญาณA Simple Grounded FDNR Based-on CDTRA and Its Application for a Sinusoidal Oscillator

บทความนี้นำเสนอ วงจรจำลองค่าความต้านทานแบบลบที่ผันแปรตามความถี่ (FDNR) โดยใช้อุปกรณ์ CDTRA เป็นอุปกรณ์แอคทีฟหลัก ต่อร่วมกันกับอุปกรณ์พาสซีฟแบบลอยอีก 4 ตัว วงจรที่นำเสนอสามารถควบคุมค่าอิมพีแดนซ์ของวงจรได้ด้วยการกำหนดค่าที่อุปกรณ์พาสซีฟ อีกทั้งวงจรมีผลกระทบต่ำเมื่ออุณหภูมิรอบข้างเปลี่ยนแปลง ทำให้สามารถนำเอาวงจรไปใช้ในงานที่มีการเปลี่ยนแปลงของอุณหภูมิได้เป็นอย่างดี ด้วยโครงสร้างของวงจรไม่ซับซ้อนจึงเหมาะสมที่จะนำไปสร้างเป็นวงจรรวม นอกจากนี้ยังได้นำเสนอการประยุกต์ใช้งานวงจรที่สังเคราะห์ขึ้นในวงจรกำเนิดสัญญาณรูปคลื่นซายน์ ผลการจำลองการทำงานด้วยโปรแกรม PSpice พบว่าวงจรทำงานได้สอดคล้องกับที่คาดการณ์ไว้ในทฤษฎีThis article proposes a simple grounded Frequency Dependent Negative Resistance (FDNR) based on CDTRA cooperating with 4 floating passive elements. The features of the proposed circuit are that; the impedance can be controlled by passive devices. Moreover, the circuit is theoretically temperature-insensitive which is preferable for using in a temperature control/measurement work. It is suitable for further fabricating in the IC architecture. The application example as a sinusoidal oscillator is included. The simulation results using PSpice are given for the introduced grounded simulator to verify the theory and to exhibit the performances of the circuit

Design, Modeling, and Model-Free Control of Permanent Magnet-Assisted Synchronous Reluctance Motor for e-Vehicle Applications

This paper describes the model-free control approaches for permanent magnet-assisted (PMa) synchronous reluctance motors (SynRMs) drive. The important improvement of the proposed control technique is the ability to determine the behavior of the state-variable system during both fixed-point and transient operations. The mathematical models of PMa-SynRM were firstly written in a straightforward linear model form to show the known and unknown parts. Before, the proposed controller, named here the intelligent proportional-integral (iPI), was applied as a control law to fix some unavoidable modeling errors and uncertainties of the motor. Lastly, a dSPACE control platform was used to realize the proposed control algorithm. A prototype 1-kW test bench based on a PMa-SynRM machine was designed and realized in the laboratory to test the studied control approach. The simulation using MATLAB/Simulink and experimental results revealed that the proposed control achieved excellent results under transient operating conditions for the motor drive’s cascaded control compared to traditional PI and model-based controls

Design, Modeling, and Model-Free Control of Permanent Magnet-Assisted Synchronous Reluctance Motor for e-Vehicle Applications

This paper describes the model-free control approaches for permanent magnet-assisted (PMa) synchronous reluctance motors (SynRMs) drive. The important improvement of the proposed control technique is the ability to determine the behavior of the state-variable system during both fixed-point and transient operations. The mathematical models of PMa-SynRM were firstly written in a straightforward linear model form to show the known and unknown parts. Before, the proposed controller, named here the intelligent proportional-integral (iPI), was applied as a control law to fix some unavoidable modeling errors and uncertainties of the motor. Lastly, a dSPACE control platform was used to realize the proposed control algorithm. A prototype 1-kW test bench based on a PMa-SynRM machine was designed and realized in the laboratory to test the studied control approach. The simulation using MATLAB/Simulink and experimental results revealed that the proposed control achieved excellent results under transient operating conditions for the motor drive’s cascaded control compared to traditional PI and model-based controls

Nonlinear Differential Flatness-Based Speed/Torque Control With State-Observers of Permanent Magnet Synchronous Motor Drives

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