จำนวน Repository ( 11 )

การศึกษาผลของกระแสฮาร์มอนิกส์ต่อค่าสูญเสียของหม้อแปลงไฟฟ้าเลื่อนเฟสและการทำให้เป็นจริงด้วยหม้อแปลงไฟฟ้าเลื่อนเฟส 15 องศา
การศึกษาผลของกระแสฮาร์มอนิกส์ต่อค่าสูญเสียของหม้อแปลงไฟฟ้าเลื่อนเฟสและการทำให้เป็นจริงด้วยหม้อแปลงไฟฟ้าเลื่อนเฟส 15 องศา

The trend of energy savings has been widely interested and phase shift transformers (HMT) have been extensively used. This paper presents the investigation of the effect of harmonic currents on losses of the HMT. In this paper a 15-degree HMT with quad secondary winding is applied to find the relationship between harmonic currents and losses of the HMT. This relation can be met by testing the active power of primary and secondary sides while the HMT supplies for two and four non-linear loads at 25% 50% 75% and 100% rated currents respectively. The results reveal that harmonic currents affect winding eddy current losses significantly and the losses for loading the two secondaries 1 and 2 are the same as loading the two secondaries 1 and 3 while both %THDi are different. However for loading the secondaries 1 and 2 the %THDi is more than 15% so it is not met IEEE 519 Std. while the HMT is supplied with four loads the %THDi has met IEEE 519 Std. and the losses are less than 57% compared to one load. As a result of these if the HMT is applied to an adjustable speed drive system it is not only reduced the harmonics but also saved the energies.

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การวางแผนและปฏิบัติการระบบไฟฟ้ากาลังในสภาวะฉุกเฉิน
การวางแผนและปฏิบัติการระบบไฟฟ้ากาลังในสภาวะฉุกเฉิน

This thesis presents an application of particle swarm optimization technique (PSO) to optimal economic dispatch analysis in power system with contingency criteria for management power system operation cost power loss and bus voltage. The objective of optimal economic dispatch for contingency in power system compared with the results of analysis power system in normal case. The study result show that when contingency occur in power system operation cost are rising. In the other hand system stability are decrease.

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ผลกระทบจากเอ็นบีทีไอต่อสมรรถนะของวงจรรวมดิจิทัลที่สร้างด้วยเทคโนโลยีฟินเฟต
ผลกระทบจากเอ็นบีทีไอต่อสมรรถนะของวงจรรวมดิจิทัลที่สร้างด้วยเทคโนโลยีฟินเฟต

In FinFET-based VLSI designs heat issues from increase of driving current with temperature and self-heating effect profoundly influence the circuit performance and reliability. This work evaluates the performance of FinFET-based combinational circuits considering BTI stress and thermal effect of supply voltage and frequency variations. The proposed simulation framework is applied to selected benchmark circuits implemented with the 14-nm tri-gate bulk FinFET technology. The experimental results reveal that as temperature increases BTI aging delay increasingly worsens yet it is overridden by performance gain from the increase in driving current. We also prove that BTI degradation is dependent on power supply and frequency through their thermal impacts. Further we introduce a DVFS based power reduction approach that scales down the supply voltage of hot circuits to maintain the performance. The results show that power reduction yielded from the proposed technique is larger for all circuits working at higher ambient temperature (as large as 66% in some experimental circuits working at 20 oC above the baseline ambient temperature) with a slight decrease in BTI degradation.

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การเปรียบเทียบกำลังทางไฟฟ้าของรถจักรดีเซลไฟฟ้า ระหว่างการตรวจวัดด้วยเครื่องติดตามระยะไกลและเครื่องมือวัดประจำสถานี
การเปรียบเทียบกำลังทางไฟฟ้าของรถจักรดีเซลไฟฟ้า ระหว่างการตรวจวัดด้วยเครื่องติดตามระยะไกลและเครื่องมือวัดประจำสถานี

Rail transport is a type of transportation that strongly influences economic due to its ability to transport a large number of passengers and products per trip relying on diesel-electric engines. The objectives of this thesis were set to investigate and develop the electrical performance tracking system of long-distance diesel electric locomotives and compare the electrical performance measured by the diesel electric locomotive performance tracking system and measured from the measuring instrument at Diesel Engine Maintenance Station in Bang Sue. The electric diesel locomotive no. 4513 (Cummins KTA50-L) was selected as the study subject of the experimentation. The results showed that the power loss of the diesel electric locomotive from the conversion of alternating current to direct current was inversely proportional to the engine speed. The power losses between the low and high engine speeds were equal to 77.11 and 2.49 percent respectively. The above data reflects the limitation of diesel electric engine performance and should lead to the construction of a database for making decision on the right engine selection suitable for the towing load of the locomotive.

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การประเมินสมรรถนะการป้องกันฟ้าผ่าในระบบส่งกําลังไฟฟ้า
การประเมินสมรรถนะการป้องกันฟ้าผ่าในระบบส่งกําลังไฟฟ้า

This Research purposes assessment of lightning performance on transmission system 69 kV in Metropolitan Electricity Authority (MEA). The case studies illustrated the lightning strike to direct top pole in order to guideline considering the critical flashover voltage value of insulator is able to withstand it and improvement lighting protection in the future. This solution analyzes using the Alternative Transient Program-Electromagnetic Transient Program (ATP-EMTP). The result found that voltage across insulator before and after improvement lightning protection by external ground wire. Factor effect to voltage across the insulators is the tower footing resistance wave of lightning current and interval between towers. It depends on relation with front time of wave. The analysis economics is very important. This Research is studying interruption cost of outage since back flashover so analysis the break even point of the installation external ground. The result found upon improvement lightning protection by installed external ground. The pay back period of that is 9 years installed ago. This result can conclusion is external ground able reduction interruption costs of outage.

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