A Study on the Summer and Winter Load Forecasting by using the Characteristics of Temperature Changes in Korean Power System

Cha, Jun-Min,Ku, Bon-Hui 대한전기학회 2014 The Journal of International Council on Electrical Vol.4 No.4

In Korean power system, the daily load variation is in accordance with the temperature changes in summer and winter time. However, it is not in accordance with temperature changes in spring and autumn time. The cooling load in summer and the heating load in winter contribute to the increasing of the load. Daily temperature changes will cause the load changes. Therefore, the temperature sensitivity is very important in improving the accuracy of the load forecasting during the summer and winter. This paper proposes the summer and winter load forecasting by using the characteristics of temperature changes in Korean power system. Based on daily peak load of summer and winter, the relationships between characteristics of temperature changes and daily peak load are analyzed in this paper. The characteristics of temperature changes are obtained by using daily peak load and high temperature data in summer and low temperature data in winter during eight years from 2001 to 2008. The sensitivity of daily load in accordance with the increase or decrease in temperature are calculated, respectively. Summer and winter load are forecasted based on the sensitivity between unit temperature changes and daily load variations. Load forecast data with better accuracy are obtained by using the proposed sensitivity than by using the ordinary daily peak load.

일사량 가중치를 활용한 평일 전력수요예측 알고리즘

문찬호(Chan-Ho Moon),권보성(Bo-Sung Kwon),배동진(Dong-Jin Bae),송경빈(Kyung-Bin Song) 한국조명·전기설비학회 2020 조명·전기설비학회논문지 Vol.34 No.6

For efficient operation of the electric power system, it is important to increase the accuracy of load forecasting. Recently, small capacity solar photovoltaic(PV) generation in South Korea is the majority of Behind-The-Meter (BTM) generation, which is one of the main factors that change the gross load. Solar radiation is a weather factor that is highly correlated with solar PV generation and closely related to BTM in South Korea. So far, solar radiation is not systematically reflected in the load forecasting algorithm, so the load forecasting error is increasing due to the BTM solar PV generation. Therefore, it is necessary to analyze the impact of the BTM and to study the load forecasting algorithm considering the BTM. As a method to reflect the impact of BTM solar PV generation on the load forecasting, the load sensitivity by cloud amount is calculated. To reflect the characteristics of solar radiation that changes monthly due to earths revolution, the load sensitivity by cloud amount with monthly solar radiation weighting is calculated. The load sensitivity by cloud amount with monthly solar radiation weighting is applied to the weekday load forecasting, and the accuracy is better than the load forecasting result applied only load sensitivity by temperature.

부하 역률을 고려한 직접부하제어 실행시 계통의 민감도 분석

채명석(Myeong-Suk Chae) 대한전기학회 2015 전기학회논문지 P Vol.64 No.4

Recently, the power load is growing larger and because of the environmental limitation of generation, the expansion of generation facilities are becoming more difficult. For that reason the importance of the demand-side resources come to be higher. One method of the demand-side resource, the DLC Program, has executed, and moreover, the loads which are available to be controlled are increasing. It should be considered of some kinds of power system components such as DLCs, because the fact that using the demand resources will be an important part of the power system. This paper considers the power factor of the load-bus which is shedded in the direct load control program. and then analyze the power system using flow sensitivity and voltage sensitivity. In this paper, we assumed two scenarios through the rank of the load power factor at each bus and to compare and evaluate each case, we used Power World for the simulation.

멀티미디어 학습자료 설계를 위한 인지부하 설문의 민감도 분석 및 학습 성취에 대한 예언변수 분석

류지헌 ( Jee Heon Ryu ) 한국교육정보미디어학회(구 한국교육정보방송학회) 2011 교육정보미디어연구 Vol.17 No.3

이 연구는 멀티미디어 학습 자료를 설계하기 위한 인지부하 설문의 민감도를 분석하기 위한 것으로 과제 난이도의 변화에 따라서 인지부하의 요인이 민감하게 반응하는지를 분석하기 위한 것이다. 설문지의 민감도를 분석하기 위해서 세 가지 방법이 적용되었는데, 1) 다차원 척도에 대한 문항 신뢰도의 점검, 2) 과제 난이도에 따른 집단 간 차이분석, 3) 이해도 검사를 통한 학습 성취에 대한 예측변수의 분석이다. 각 연구목적의 달성을 위하여 1) 문항의 내적 일관성 및 구인 신뢰도의 비교, 2) 구조방정식에 의한 잠재평균의 분석, 3) 다변량회귀분석을 적용했다. 이 연구에는 212명의 대학생이 참여했으며, 쉬운 과제와 어려운 과제로 구성된 학습활동에 참여했다. 과제 난이도에 따른 민감도 차이를 분석하기 위해서 잠재평균분석 기법을 적용했다. 이 기법은 구조방정식을 적용함으로써 측정오차를 고려한 집단 간 차이를 분석하기 위한 것이다. 각 분석기법을 통하여 다음과 같은 결과를 얻을 수 있었다. 첫째, 모든 인지부하요인에 대한 구인 신뢰도 및 문항 신뢰도는 수용범위 내에서 구성되는 것을 확인할 수 있었다. 문항 내적 일관성 및 다차원 척도에 대한 구인 신뢰도는 모두 수용 할 수준의 결과를 보였다. 둘째, 잠재평균분석에서는 과제 난이도 지각과 자기평가에서 유의미한 차이가 나타났다. 과제의 난이도 차이가 발생할 때, 과제에 대한 학습자의 난이도 지각과 자신의 인지활동에 대한 자기평가 점수가 유의미하게 달라지는 것으로 나타났다. 셋째, 이해도 검사에 대한 회귀분석의 결과에서는 과제 난이도에 따라서 예측변수가 다르다는 것을 확인할 수 있었다. 쉬운 과제에서는 과제 난이도를 높게 지각한 학습자일수록 사후평가의 성취가 떨어지는 것으로 나타난 반면 어려운 과제에서는 자기평가를 높게 지각하는 학습자일수록 성취가 높은 것으로 나타났다. This study was to identify the relationships among the five cognitive load factors: 1) task demand, 2) mental effort, 3) perceived task difficulty, 4) self-evaluation, and 5) usability of the learning material. Particularly, for this study it was a purpose of testing the sensitivity of the cognitive load survey instrument by the different levels of task difficulties. 212 students were participated into the lable. Two different levels of task were presented to the participants to identify how well the differences of task difficulty is sensitive. Specifically, this study set up three sub-research goals. First, it was to evaluate the reliability of each cognitive load factor. For the analysis Cronbach`s alpha and construct reliability were tested. The result revealed that the cognitive load factor survey showed acceptable reliability. Second, a latent mean comparison was conducted. The result showed that the perceived task difficulty and self-evaluation had significant an impact on the cognitive load factors. Third, a multiple-regression was applied to measure what cognitive load factors may have impact on the task performance. When participants were in an easy task, the perceived task difficulty was a significant variable to predict the levels of learning achievement. However, when participants were in a hard task, the self-evaluation showed a significant prediction power on the learning achievement.

부하 시뮬레이션을 이용한 건축적 요소기술의 민감도 분석

이정재,박주양 東亞大學校 建設技術硏究所 2009 硏究論文集 Vol.32 No.2

To meet the increasing demand with the limited resource, every country is trying all-out to find a solution. A large part of energy demand is used in the building, so a Korean Energy Saving Design Standard which is right to the country conditions is immediately needed. This study is trying to analyze the sensitivity of architectural elements through a simulation which considered architecture, electricity, machine overall with the typical thermal load analysis program Transys and to present a quantitative data to set up an adequate Energy Saving Design. The results of this study are as follows. Sensitivity analysis show that setting windows are more sensitive than other factors which we adopt at cooling load, and setting temperature are more sensitive than other factors which we adopt at heating load. 2005 년 2월 16 일 각국의 온실가스 감축을 의무화 하는 교토의정서가 공식 발효됨에 따라 2013년 이후 감축의무 이행이 불가피해질 우리나라는 온실가스 저감을 위한 추가적인 대책이 없을 경우 온실가스 배출량은 2000년 대비 2030년까지 25~90% 증가할 전망이며, 에너지 사용으로 인한 C0_(2) 배출량은 같은 기간 동안 45~110% 증가할 것으로 예상된다. IPCC WG3 보고서에 따르면 현재 우리나라 건물부문의 경우 부문별 온실가스 감축 잠재량이 타 분야와 비교해 가장 큰 것으로 나타나고 있다. 따라서 의무 감축 국가 편입에 대비하여 건물에너지의 감축비용, 감축 잠재량 등을 면밀히 분석하고, 이를 통한 감축목표 설정 등 체계적인 추진 전략이 필요하다. 이에 현재 전 세계적으로 건물 저에너지 요소기술의 적용을 통해 건물 에너지 소비량 절감 에 의한 목표 C0_(2) 감축량을 달성하기 위한 연구 및 개발이 활발히 진행되고 있다. 이러한 현실에 대응하여 우리나라도 건물 에너지 절감에 대한 필요성을 인식하고 여러 가지 저에너지 요소기술들을 개발하고 있다. 건물 에너지절감 요소기술은 크게 건축 계획적 요소기술과 건축설비관련 요소기술 그리고 건물 유지관리 요소기 술로 나눌 수 있다. 특히 건축 계획적 요소기술은 원천적으로 건물에 발생하는 냉난방부하 저감을 통해 에너지를 절감한다는 측면에서 매우 중요하다. 이에 본 연구에서는 건물에서 발생하는 에너지 소비를 줄이기 위해 건물 용도별 에너지 소비에 많은 부분을 차지하고 있는 사무소건물을 대상으로 Tmsys를 이용하여 건축 계획적 요소기술인, 실내설정온도, 방위, 차양길이, 창면적비 감소율, 단열재 두께, 필요 환기량, 창의 종류를 변수로 선정하고 그에 따른 인자들의 변화를 통해 부하를 산정하여 민감도를 분석하고자 한다.

A Study on Voltage Sag Assessment for Multiple Sensitive Loads Based on Probabilistic Prediction

Chae Hakyung,Park Chang-Hyun 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3

This paper presents a voltage sag assessment method that considers the voltage tolerance characteristic of multiple loads in a power system. In general, load sensitivity to a voltage sag is characterized by a voltage magnitude and duration expressed as a voltage tolerance curve (VTC). In order to assess the impact of voltage sags on a load, it is essential to estimate the expected voltage sag frequency that reflects the load’s VTC. However, most of the previous assessment methods have focused on rectangular shape VTCs; hence, there is a limitation in that these methods cannot reflect various load sensitivities. This paper proposes an effective method of voltage sag assessment based on vulnerable areas and numerical interpolation by considering diagonal shape as well as rectangular shape VTCs. And the voltage sag duration is estimated using a probability model based on the historical data of protection systems. In addition, the proposed method significantly reduces computational burden for voltage sag assessment while showing similar results to the existing methods. In the case study, the performance of the proposed method was verified using the IEEE-30 bus system with various multiple sensitive loads.

기상 확률 모델 및 기상 민감도를 이용한 연중 주별 전력수요 예측에 관한 연구

위영민(Young-Min Wi),민용기(Yongki Min) 한국조명·전기설비학회 2016 조명·전기설비학회논문지 Vol.30 No.5

Load forecasting is an essential component for operating and planning power systems. There are various prediction time horizons in accordance with applications. This paper proposes a forecasting model for mid-term load forecasting which is used for planning electricity supply and demand, electrical equipment maintenance schedule, and demand response programs. This paper presents weekly peak load forecasting method using time series and temperature sensitivity model with temperature stochastic modeling. Using Monte-Carlo simulation, the proposed method can also make probability distribution of weekly peak loads. The results of case studies show the effectiveness of the proposed load forecasting method.

무효전력 민감도와 부하지속곡선을 활용한 적정 부하역률의 효과적인 산정 기법에 관한 연구

이병하(Byung Ha Lee),황승호(Sung-Ho Hwang) 대한전기학회 2012 전기학회논문지 Vol.61 No.12

In this paper, a methodology to use load duration curve and the reactive power factor sensitivity of generation cost is proposed for analyzing the effects of load power factor effectively. A great deal of cases of power systems are classified into several patterns according to the characteristics using load duration curve, and the overall effects of load power factor are assessed by integrating the analysis results of load power factor in all the patterns. The reactive power sensitivity of generation cost and the integrated costs such as generation cost, investment cost, voltage variation penalty cost and CO2 emission cost are used for determining an appropriate load power factor. A systematic procedure for effective analysis of load power factor is presented. It is shown through the application to the practical power system of KEPCO(Korea Electric Power Corporation)that the effects of load power factor can be analyzed effectively using load duration curve and reactive power factor sensitivity.

The Temperature Sensitivity of the Commercial Load in KOREA

Yoon, Yong-Beum,Kang, Dong-Phil,Yoon, Yong-Tae 대한전기학회 2013 The Journal of International Council on Electrical Vol.3 No.2

This paper presents the temperature impacts on daily peak load of commercial load in KOREA. This research focuses on the overall summer and winter peak load characteristics and the impact of temperature change on the commercial load. Load data of the last five years are used to analyze the temperature sensitivity of commercial load sensitivity.

Probabilistic analysis of buckling loads of structures via extended Koiter law

Ikeda, Kiyohiro,Ohsaki, Makoto,Sudo, Kentaro,Kitada, Toshiyuki Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.1

Initial imperfections, such as initial deflection or remaining stress, cause deterioration of buckling strength of structures. The Koiter imperfection sensitivity law has been extended to describe the mechanism of reduction for structures. The extension is twofold: (1) a number of imperfections are considered, and (2) the second order (minor) imperfections are implemented, in addition to the first order (major) imperfections considered in the Koiter law. Yet, in reality, the variation of external loads is dominant over that of imperfection. In this research, probabilistic evaluation of buckling loads against external loads subjected to probabilistic variation is conducted by extending the concept of imperfection sensitivity. A truss arch subjected to dead and live loads is considered as a numerical example. The mechanism of probabilistic variation of buckling strength of this arch is described by the proposed method, and its reliability is evaluated.