• KEPCO Journal on Electric Power and Energy
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• 제3권2호
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• pp.127-131
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• 2017

The present paper describes the slagging field data obtained with the one-dimensional process model for the 500 MW tangentially coal fired boiler in Korea. To obtain slagging field data in terms of thermal resistances [$m^2{\cdot}^{\circ}C/kW$], a number of plant data were collected and analyzed with the one-dimensional modelling software at 500 MW full load. The slagging field data for the primary superheater were obtained for six coal blends, and compared with two TMA (Thermo-Mechanical analyzer) slagging indices and the numerical slagging index, along with the conventional slagging indices which were modified with the ash loading. The advanced two TMA indices for six blended coals give a good slagging tendency when comparing them with the slagging field data, while the modified conventional slagging indices give a relatively poor agreement.

• KEPCO Journal on Electric Power and Energy
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• 제2권4호
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• pp.615-618
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• 2016

Electrochemical noise(EN) has been used to analyze the deterioration of coating films of offshore wind substructures. In this study, prototype sensors using EN have been developed to detect the corrosion rate. To verify the reliability of sensors, experiments were conducted both in the laboratory and offshore using probe and standard samples. New analysis and data processing techniques show that the sensor can provide useful information about the corrosion rate.

• KEPCO Journal on Electric Power and Energy
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• 제6권3호
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• pp.297-303
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• 2020

The reaction of carbon dioxide with the amine-based absorbents which have various substituents in the molecule was described. In the case of MEA which is a representative primary amine, the absorption reaction was proceeded very fast while the regeneration reaction was took place slowly due to the strong bond strength between the absorbent and carbon dioxide. The more substituents on N atom of the absorbent, the slower the absorption reaction between carbon dioxide and the absorbent, which in turn causes faster the regeneration rate from the reaction intermediate, carbamate.

• KEPCO Journal on Electric Power and Energy
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• 제8권2호
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• pp.61-68
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• 2022

In this paper, the change history of various types of MV (Medium Voltage) cables was investigated. In addition, the statistical life expectancy of each type was calculated by using the operation data and the failure data. For cut-off year, 10 years was applied, and realistically applicable statistical life expectancy was calculated by correcting the cause of failure entered by mistake. The life expectancy of FR-CNCO-W was calculated as 51.2 years, CNCV-W 38.1 years, and CNCV 31.4 years and the overall average is 33.8 years. Currently, the life expectancy of TR CNCV-W is 29.4 years, but it is estimated that the lifespan will be extended if failure data is accumulated. As a result, it is expected that life expectancy results can be applied to Asset Management System (AMS) in the future.

• KEPCO Journal on Electric Power and Energy
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• 제7권1호
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• pp.115-123
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• 2021

Through machine learning-based load prediction, it is possible to prevent excessive power generation or unnecessary economic investment by estimating the appropriate amount of facility investment in consideration of the load that will increase in the future or providing basic data for policy establishment to distribute the maximum load. However, in order to secure the reliability of the developed load prediction model in the field, the performance comparison verification between the distribution line load prediction models must be preceded, but a comparative performance verification system between the distribution line load prediction models has not yet been established. As a result, it is not possible to accurately determine the performance excellence of the load prediction model because it is not possible to easily determine the likelihood between the load prediction models. In this paper, we developed a reliability verification system for load prediction models including a method of comparing and verifying the performance reliability between machine learning-based load prediction models that were not previously considered, verification process, and verification result visualization methods. Through the developed load prediction model reliability verification system, the objectivity of the load prediction model performance verification can be improved, and the field application utilization of an excellent load prediction model can be increased.

• KEPCO Journal on Electric Power and Energy
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• 제6권2호
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• pp.163-171
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• 2020

전력연구원에서 설계한 5 MW급 일괄설치시스템의 예인안정성 및 내항성능 검증을 위해 수조모형시험을 실시하였다. 1/48 축소모형을 만들어 정수 및 파랑 중 시험을 수행하였다. 실선기준 4, 5, 6 knots의 대응속도로 예인하며 예인선의 장력을 계측하고, 실선의 필요 예인 동력을 추정하였다. 또한, 관성계측장치를 이용하여 모형의 6자유도 운동을 계측하였으며, 파랑 중 구속모형시험을 통해 내항성능을 확인하였다.

• KEPCO Journal on Electric Power and Energy
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• 제3권2호
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• pp.113-117
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• 2017

As the competition in the manufacturing market for small and medium sized generators is intensifying, there is increasing pressure to reduce production cost. Manufacturing the generator stator windings with global vacuum pressure impregnation (GVPI) is a very effective way to reduce costs. However, the stator winding has a fatal disadvantage in that the insulation wears due to vibration in the slot. KEPRI (KEPCO Research Institute) conducted insulation diagnosis for three generators in KOMIPO (Korea Midland Power Co., Ltd.) which were manufactured by GVPI and operated for about 17 years. Insulation diagnosis showed that deterioration of insulation has progressed significantly. Therefore, KEPRI recommended replacing the stator windings of all three generators. In this paper, the insulation properties of the generator stator winding with global GVPI are described by comparing and analyzing the insulation diagnosis results and visual inspection for stator windings.

• KEPCO Journal on Electric Power and Energy
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• 제2권3호
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• pp.403-407
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• 2016

In general, drum-type boilers are designed for base load duty and applied under constant pressure operation mode. Recently, however conditions often occur that even drum-type boilers have to operate at partial load conditions. A feasibility study on adopting the sliding pressure operation for drum-type boiler was conducted, and corresponding performance changes and effects on the equipment were analyzed by utilizing a process simulation model. As a result, the conclusion was reached that drum type boilers are able to adopt the sliding pressure operation and can improve of net efficiency at part load operation in spite of the Rankine cycle efficiency reduction due to the decreases in main steam pressure. Because of thank to improvement of high pressure turbine stage-1 internal efficiency and power savings of boiler feed water pump. The sliding pressure operation is advantageous in terms of stress level relief for boiler tube as well as maintaining the rating steam temperature at part load condition. However, cautions are required because the drum boilers have poor dynamic response characteristics which may get worse during the sliding pressure operation.

• KEPCO Journal on Electric Power and Energy
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• 제2권4호
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• pp.595-600
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• 2016

다상 고정층 촉매반응기(Multiphase catalytic fixed-bed reactor)에서 기체 유동과 관련, 반응기 내부 구조 디자인에 따른 feed 가스의 분산성 변화를 분석하였다. 다상 촉매반응기의 경우 feed gas의 투입방법이 전체 공정의 반응효율을 크게 결정하는바 본 연구에서는 산업현장에서 활용도가 높은 환형 가스 주입부로 구성된 다상 고정층 촉매반응기를 대상으로 다양한 조건하에서 촉매 반응기 내부에서의 feed가스 분산성 변화를 분석하였다. 다상 촉매반응기의 feed gas 주입과 관련하여 다양한 방안이 제시되고 있는데 그 중 환형 가스 주입방식을 활용하는 방법은 타 기술대비 상대적으로 저렴한 투자비와 좁은 작업공간하에서 기체의 분산성을 향상 시킬수 있는 특징이 있어 실제 상업 공정에서의 활용성이 매우 높다. 본 논문에서는 특히 기-고 촉매 반응기 내부 반응기체의 분산성 향상을 위해 환형 가스 주입장치 내부에 설치된 가스 주입홀 구성방법에 따른 반응기 내부 유동을 분석하였다. 분석결과 주입홀의 위치가 가스 투입라인의 접선방향에 위치하는 것은 전체 분산성에 큰 영향을 주지 못하며 대부분 가스투입 입구와 맞은편 부분에 위치하는 경우 분산성이 향상되는 것으로 분석되었다. 결과적으로 환형 가스주입장치의 최적 설계는 feed 가스의 분산성에 큰 영향을 미치므로 초기단계에서 이러한 점을 고려한 설계 및 분석연구가 선행되어야 할 것으로 사료된다.

• KEPCO Journal on Electric Power and Energy
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• 제1권1호
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• pp.1-8
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• 2015

When the line and switchgear of the substation system are disconnected, ferro-resonance can occur. This happens even if the capacitive reactance and inductive reactance are not equal, which are not common resonance conditions. Resonance conditions vary depending on the busbar configuration environment. Although the damping resistance method applying the existing saturable reactor to cope with ferro-resonance has been successfully applied on site, there can be loss of normal function during long-term operation. The reason is because the rise in the operating frequency of saturable reactors means the saturation number is increased. Therefore, it can no longer function as saturable reactor since the resistor having inadequate capacity is burned out. To address this problem, in this paper, an EMTP-based simulation test was performed by designing and applying a dual reactor method, which adds an extended divergence reactor to the 1st side of the VT. The test result confirms that when the divergence reactor is inserted, the voltage and current values obtained at the 1st side and 2nd side of the VT as well as current values of divergence reactor part were stabilized from the transient phenomena and return to normal values. When compared with existing measures, although this method is similar in adding having a reactor added to a system regarding ferro-resonance, it has the advantage of being able to prevent ferro-resonance in advance since the reactor is added before the system is saturated. In addition, because it does not use damping resistance, it can extend the equipment life and stabilize its operation. Therefore, there are a lot of differences in terms of its operating characteristics and achivement of goal between the conventional method and new divergence reactor method.