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이상중(Sangjoong Lee),김순기(Soonki Kim),양성덕(Seongdeog Yang),박건복(Gunbook Park) 한국조명·전기설비학회 2010 한국조명·전기설비학회 학술대회논문집 Vol.2010 No.5월
G8 summit meeting was held in July 2008 and decided to set up a long-term goal, by 2050, reducing the greenhouse emissions by half of those in 1990. In November am, Korea government pronounced to reduce the national CO₂ emission by 30% of BAU by 2020. Power industries in Korea produce most of its electricity by burning fossil fuels, and emit approximately 28% of national CO₂ emissions. Therefore, it is very important to calculate CO₂ emissions of electric power plants. In this paper, we present a method to calculate the hourly CO₂ emission for a thermal power plant burning mixture of coal and oil, using the performance test data and coal-oil mix rate. An example for calculating the CO₂ emissions per hour is also demonstrated.
P-Q 부하가 주어진 배전선로 두 부하점의 약식(略式) 전압계산 - Simplified Voltage-Power Formula를 이용한 배전선로의 전압계산 -
이상중(SangJoong Lee),김주철(JuChul Kim) 한국조명·전기설비학회 2022 조명·전기설비학회논문지 Vol.36 No.4
For a distribution power system, the load connected to a load point is represented by kVA or P+jQ form in general. The so-called two-bus V-P formula(=Voltage-Power formula) composed of bus voltages and load power P,Q and a calculation example for load voltages in a distribution line with two P-Q load points have been presented in recent publications. While the result by conventional ‘Equivalent resistance method’ is approximate, the calculation using V-P formula has yielded an exact solution. However, the original V-P formula that includes the power line loss makes the equation much complicated to obtain solutions using a scientific calculator. This paper presents a new voltage calculation using the simplified V-P formula in which the line power loss is eliminated for calculation simplicity, and illustrates an example calculation for a distribution line with two P-Q load points to compare with existing methods. Calculation result by the proposed simplified V-P formula has shown an acceptable error rate for using in the industrial fields.
An Exact Voltage-Power Equation with no Angle Terms for an AC Two-bus System
SangJoong Lee(이상중),Ju-Chul Kim(김주철) 대한전기학회 2020 전기학회논문지 Vol.69 No.5
This paper presents a voltage-power equation for a two-bus system with a complex load S=P+jQ connected through a transmission line with admittance Y=G-jB. The proposed formula is represented by the magnitudes of bus voltages, active and reactive load power and transmission line admittance. No angle terms are included in the formula and no complex number calculation is needed. Sample calculations for bus voltages using proposed formula show exact solutions, which are compared with existing calculation methods.
Ju-Chul Kim(김주철),SangJoong Lee(이상중) 대한전기학회 2020 전기학회논문지 Vol.69 No.6
The angle reference, the reference for the angles of all bus voltages in a power system, has been specified conventionally on the slack bus in power flow computation(e.g., θ₁=0), however, it can be specified on any bus in the system without affecting the power flow solution. In this paper, loss sensitivities, ∂Ploss/∂PG, ∂Ploss/∂QG, Qloss/∂PG and ∂Qloss/∂QG, of all generators including the slack bus are derived by specifying the angle reference on a load bus that has no generation using the nature of the Jacobian matrix which is re-constructed by transposition of the angle reference bus. With these loss sensitivities, this paper shows the following four example applications to power system computation: New calculation of penalty factors for classical ELD computation Optimal P-Q generation for cost minimization Optimal P generation for system loss minimization Optimal P-Q generation for system loss minimization Derived loss sensitivities and application algorithms are tested and verified on a sample system.
발송배전기술사 고시 출제경향 분석 및 대학 교과과정 반영에 대한 고찰
권준오(Jun-Oh Kwon),이상중(Sangjoong Lee) 한국조명·전기설비학회 2012 조명·전기설비학회논문지 Vol.26 No.4
The government has pushed ahead with the establishment of a connection system among education-task-qualification with regards to the promotion of engineering industry, but there has been a lack of pertinent data. In this regard, this study investigated the ways of connecting universities’ engineering education with Electrical Professional Engineer examination. The results show that the tendency of questions consists of 30[%] of transmission, 16[%] of basic theory, 14[%] of transformer, 14[%] of generation, 9[%] of new technology, 11[%] of other relevant fields. This study also presents a survey on the relationship between the engineer’s license and college curriculum. The curriculum of Electrical Engineering Department of a leading National University in Seoul is investigated in relation to the Examination. Some learning materials for successful completion of the university curriculum and acquisition of the Professional Engineer license are also recommended.