• Title/Summary/Keyword: Power main transformers

Search Result 59, Processing Time 0.021 seconds

A Three-Phase Line-Interactive UPS System to Eliminate the Inrush Current Phenomenon during Switching-in of an Auxiliary Load while Powering the Main Load

  • Bukhari, Syed Sabir Hussain;Ayub, Muhammad;Kwon, Byung-il
    • Journal of Electrical Engineering and Technology
    • /
    • v.13 no.4
    • /
    • pp.1623-1630
    • /
    • 2018
  • Normally, various auxiliary loads are installed along with the main load in industrial applications. Usually, load transformers are used to convey such types of auxiliary loads. The transformers become energized when the loads are turned-on, consequently, high amplitude of inrush current appears at the output of the uninterrupted power supply (UPS) system. To mitigate these high current amplitudes, this manuscript suggests a three-phase line-interactive UPS system to counter the inrush current during the turning-on of the auxiliary load transformer while powering the main load by using a current controlled inverter. Experimental results of a laboratory-sized prototype are provided in the support of the proposed UPS system for validation.

Selection of Transformer for the Augmentation of an Existing AIS EHV Substation in Hilly Terrain at 3000m+ Altitude

  • Kim, Kwang-Soo;Kang, Byoung-Wook;Kim, Jae-Chul
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.26 no.12
    • /
    • pp.28-36
    • /
    • 2012
  • Augmentation of existing EHV substations located in hilly terrain and at high altitude require many different considerations as compared to substations located in plain areas and at lower altitude. Owing to high altitude and steep terrain, meticulous engineering and preparations are required, considering the actual available space at the existing substation. Historical fault events too must be considered to enhance reliability and performance of the substation equipment. This paper proposes ways to augment the existing 2 banks of 20MVA, 220/66kV power transformers ($3{\times}6.67MVA$, single-phase) to $2{\times}50$/63MVA, 220/66kV power transformers to meet continuously increasing demand of the capital city over the next 20 years. Upgrading and augmentation of existing substations, especially the main transformers and associated equipment, require replacement with minimum or no disturbance to the existing power supply system. Considerations should also be made during engineering and design, the operational flexibilities, maintenance aspects, future expandability and value addition, in terms of reliability and space usage of the existing substation.

Assessment of Insulation Condition in Large Transformers (대형변압기 절연상태 평가)

  • Kim, Hee-Dong;Kong, Tae-Sik;Lee, Young-Jun;Park, Jae-Jun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2004.07a
    • /
    • pp.499-502
    • /
    • 2004
  • In order to detect of insulation problems an early, transformer has to be performed the several tests. The ac current and tan6 of transformer winding insulation were investigated by Schering bridge. Partial discharge(PD) tests are used to evaluate the insulation condition of transformer. The moisture content measurement was conducted using RVM(recovery voltage meter). The RVM test can show that the problem is affecting the paper insulation of transformer. The value of moisture content was 2.3% in main transformer. The insulations of four transformers were judged to be in good condition.

  • PDF

Environmental Noise Evaluation of the Boundary Areas for 1200MW Combined Cycle Power Plant (1200MW 복합화력 발전소가 부지경계에 미치는 환경소음 예측)

  • 이현;김연환;김희수;배용채;김성휘
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2001.05a
    • /
    • pp.1056-1061
    • /
    • 2001
  • This paper describes the evaluation of noise influence of residental and boundary areas from power plant noise sources of 1200MW combined cycle power plant. Noise assessments are carried out by based on the ISO 3744, ISO 9613-1 and ISO 9613-2 to predict the noise distribution to satisfy the recommended noise level at specific locations and to calculate properly the octave noise power of main noise sources such as power transformers. air-intakes, stacks.

  • PDF

Analysis of Produced By-products Due to Oil/Paper Degradation on Power Transformers (전력용 변압기의 열화에 의해 생성된 부산물의 분석)

  • Kim, Jae-Hoon;Han, Sang-Ok
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.56 no.9
    • /
    • pp.1561-1565
    • /
    • 2007
  • According to thermal degradation on power transformers, it is known that electrical, mechanical and chemical characteristics for power transformer's oil-paper are changed. In the chemical property, especially, when the kraft paper is aged, the cellulose polymer chains break down into shorter lengths. It causes decrease in both tensile strength and degree of polymerization of paper insulation. Also the paper breakdown is accompanied by an increase in the content of various furanic compounds within the dielectric liquid. It is known that furanic components in transformer oil come only from the decomposition of insulating paper rather than from the oil itself. Therefore the analysis of furanic degradation products provides a complementary technique to dissolved gas analysis for monitoring transformers when we evaluate the aging of insulating paper by the total concentration of carbon monoxide and carbon dioxide dissolved in oil only. Recently, the analysis of furanic compounds by high performance liquid chromatography(HPLC) using IEC 61198 method for estimating degradation of paper insulation in power transformers has been used more conveniently for assessment of oil-paper. It is know that the main products which is produced by aging are 2-furfuryl alcohol, 2-furaldehyde(furfural), 2-furoic acid, 2-acetylfuran, 5-methyl-2-furaldehyde, and 5-hydroxymethyl-2-furaldehyde. For investigating the accelerated aging process of oil-paper samples we manufactured accelerating aging equipment and we estimated variation of insulations at $140^{\circ}C$ temp. during 500 hours. Typical transformer proportions of copper, silicon steel and iron have been added to oil-paper insulation during the aging process. The oil-paper insulation samples have been measured at intervals of 100 hours. Finally we have analyzed that 2-furoic acid and 2-acetylfuran products of furanic compounds were detected by HPLC, and their concentrations were increased with accelerated aging time.

Diagnosis Method for Power Transformer using Intelligent Algorithm based on ELM and Fuzzy Membership Function (ELM 기반의 지능형 알고리즘과 퍼지 소속함수를 이용한 유입변압기 고장진단 기법)

  • Lim, Jae-Yoon;Lee, Dae-Jong;Ji, Pyeong-Shik
    • The Transactions of the Korean Institute of Electrical Engineers P
    • /
    • v.66 no.4
    • /
    • pp.194-199
    • /
    • 2017
  • Power transformers are an important factor for power transmission and cause fatal losses if faults occur. Various diagnostic methods have been applied to predict the failure and to identify the cause of the failure. Typical diagnostic methods include the IEC diagnostic method, the Duval diagnostic method, the Rogers diagnostic method, and the Doernenburg diagnostic method using the ratio of the main gas. However, each diagnostic method has a disadvantage in that it can't diagnose the state of the power transformer unless the gas ratio is within the defined range. In order to solve these problems, we propose a diagnosis method using ELM based intelligent algorithm and fuzzy membership function. The final diagnosis is performed by multiplying the result of diagnosis in the four diagnostic methods (IEC, Duval, Rogers, and Doernenburg) by the fuzzy membership values. To show its effectiveness, the proposed fault diagnostic system has been intensively tested with the dissolved gases acquired from various power transformers.

Abnormal Resonance Noise Phenomenon and Effect through Exhaust Gas Passageway in Urban Combined Power Plant (도심지 복합화력 배가스 통로에서의 이상 소음 현상과 영향)

  • Kim, Yeon-Whan;Lee, Young-Shin;Bae, Yong-Chae;Lee, Hyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2004.11a
    • /
    • pp.866-869
    • /
    • 2004
  • Power transformers, air-intakes and stacks in the urban combined power plant are main noisy sources. Because of Inhabitant complaint by abnormal noise transferred from the power plant. the noise was investigated at power plant and uptown area. The result of diagnosis made the acoustic resonance phenomenon by 580Hz's combustion dynamic pressure with the standing wave mode of sound fields in exhaust passageway of gas turbine into main noise source of public complain. The abnormal noise is caused by the resonance exhaust noise transferred through stacks of power plant.

  • PDF

A Study on the Harmonics Effect of Ratio Differential Relay for Transformer Protection (변압기 보호용 비율차동계전기의 고조파 영향에 관한 연구)

  • Kim, Kyung-Chul;Hwang, Young-Rok;Kho, Hun;Jung, Dong-Won;Chung, Hae-Sung;Lee, Dong-Wook;Jeong, Chae-Ho;Lee, Jae-Yoon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.28 no.6
    • /
    • pp.99-105
    • /
    • 2014
  • Power transformers are applied throughout the power system to connect systems of different voltage to one another. Since a ratio differential relay offers high sensitivity in detection of internal faults in power transformers, it is widely used in the main protection system. The use of nonlinear devices such as rectifiers and other devices utilizing solid state switching have been increased in industry during recent years. For nonlinear loads, the load current is not proportional to the instantaneous voltage. This situation creates harmonic distortion on the system. The harmonic could differential relay misoperation if not recognized. This paper aims at analyzing and probing into the influences of harmonics on a ratio differential relay for power transformer protection.