• 전기학회논문지P
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• 제64권2호
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• pp.67-73
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• 2015

Distance relay is widely used for the protection of long transmission line. Most of distance relay used to calculate line impedance by measuring voltage and current using DFT. So if there is a computation error due to the influence of phasor by DC offset component, due to excessive vibration by measuring line impedance, overreach or underreach can be occurs, and then abnormal and non-operation of distance relay can be issue. It is very important to implement the robust distance relaying that is not affected by DC offset component. This paper describes an enhanced distance relaying based on the DC offset elimination filter to minimize the effects of DC offset on a long transmission line. The proposed DC offset elimination filter has not need any prior information. The phase angle delay of the proposed DC offset filter did not occurred and the gain error was not found. The enhanced distance relay uses fault current as well as residual current. The behavior of the proposed distance relaying using off-line simulation has been verified using data about several fault conditions generated by the ATP simulation software.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.64-69
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• 2013

For power system protection, the distance relay settings are important. Apparent factor is a necessary parameter in distance relay settings. Apparent factors have to be calculated when setting the distance relays and doing the resetting in case of configuration change in power system. The problem is that the current method to calculate apparent factor requires tools and plenty of time to do fault analysis and this method is complex especially in case of configuration change. Therefore this paper proposes a fast algorithm to calculate apparent factor without the fault analysis. Test results prove that this algorithm is simple and accurate by simulation.

• 대한가정학회지
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• 제20권4호
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• pp.205-223
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• 1982

This study was devised to investigate the juveniles' psychological distance to their parents and related variables. 456 respondents, consisted of 116 middle school boys, 101 high school boys, 114 middle school girls and 125 high school girls, were sampled. The psychological distance was measured by the semantic differential method, and the statistical data were verified by the analysis of variance through computer system. The main results are found as follows. 1. The average mark of the juveniles' psychological distance to their parents was 54.73(78.19%)/70(100%) and the mark of high school girls was highest and high school boys lowest. 2. The variables influencing on the juveniles' psychological distance to their parents were varied buy the groups. 1) Middle school boys; home atmosphere(p＜.001), social and economical status of home (S.E.S; p＜.01), number of intimate friends(p＜.05), rearing attitudes of parents(p＜.05). 2) High school boys; home atmosphere(p＜.001), age of father(p＜.05), protection of mother(p＜.05) 3) Middle school girls; home atmosphere(p＜.001), rearing attitudes of parents (p＜.001), S.E.S of home(p＜.001).

• Corrosion Science and Technology
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• 제21권1호
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• pp.1-8
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• 2022

The use of cathodic protection for metals can be achieved by sacrificial anode CP or impressed current CP, or a combination of both. Cathodic protection is a highly effective anti-corrosion technique for submerged metals or metals in soil. But because the non-immersion atmospheric automobile environment is a high resistance environment, it is limited by fundamental cathodic protection. However, the application of cathodic protection to automobiles is attractive because of the possibility of maintaining corrosion resistance while using lower-cost materials. A commercially available product for automobiles that uses both sacrificial anode CP and impressed current CP was tested in a periodic salt spray environment to investigate the performance of the devices. Experimental results show that the metal to be protected has different anti-corrosion effects depending on the distance from the anode of the device, but it is effective for the entire 120 cm long specimen exposed with one anode. The cathodic protection is effective because the conductive tape attached to the anode of the structure to be protected acts as a constant electrolyte in wet and dry conditions. The results show that the entire standard passenger car can be protected by cathodic protection with 4 anodes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.196-198
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• 2002

This paper represents a new approach for the protective relay of power transmission lines using a Artificial Neural Network(ANN). A different fault on transmission lines need to be detected, classified and located accurately and cleared as fast as possible. However, The protection range of the distance relay is always designed on the basis of fixed settings, and unfortunately these approach do not have the ability to adapt dynamically to the system operating condition. ANN is suitable for the adaptive relaying and the detection of complex faults. The backpropagation algorithm based multi-layer perceptron is utilized for the learning process. It allows to make control to various protection functions. As expected, the simulation result demonstrate that this approach is useful and satisfactory.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권3호
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• pp.906-918
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• 2012

Wireless Fidelity (WiFi) and Wireless microphone are assumed to operate on adjacent channels in TV White Spaces(TVWS). The Scenario of WiFi potentially interfering with Wireless microphone is analyzed through Minimum Coupling Loss (MCL) and Spectrum Engineering Advanced Monte Carlo Analysis Tool (SEAMCAT) based on the Monte-Carlo simulation method. In the case of single WiFi interfering with Wireless microphone, the protection distance between WiFi and the Wireless microphone should be at least 25.12 m to avoid WiFi impact on Wireless microphone. When the active number of WiFi is 12, the guard band between WiFi and Wireless microphone should not be less than 4.97 MHz to guarantee that WiFi does not interfere with the Wireless microphone.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.217-219
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• 2003

This paper presents a distance relaying algorithm for a transmission line protection with MAS. First, the voltage and fault current of the opposite side are represented as a function of those of the measuring end using source voltages of both ends. These voltages are assumed to be obtained from the transformers protecting agents, periodically in normal state. Then, the fault location expression, independent of fault resistance, is derived with voltage and current in only one end of faulted line used. The suggested algorithm is applied to a simple system with two power sources to show its effectiveness.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.533-540
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• 2017

Distance relay identifies the type and location of fault by measuring the transmission line impedance. However any other factors that cause miss calculating the measured impedance, makes the relay detect the fault in incorrect location or do not detect the fault at all. One of the important factors which directly changes the measured impedance by the relay is series capacitive compensation (SCC). Another factor that changes the calculated impedance by distance relay is fault resistance. This paper provides a method based on the combination of distance and differential protection. At first, faulty transmission line is detected according to the current data of buses. After that the fault location is calculated using the proposed algorithm on the transmission line. This algorithm is based on active power calculation of the buses. Fault resistance is calculated from the active powers and its effect will be deducted from calculated impedance by the algorithm. This method measures the voltage across SCC by phasor measurement units (PMUs) and transmits them to the relay location via communication channels. The transmitted signals are utilized to modify the voltage signal which is measured by the relay. Different operating modes of SCC and as well as different faults such as phase-to-phase and phase-to-ground faults are examined by simulations.

• Journal of Radiation Protection and Research
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• 제8권1호
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• pp.33-37
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• 1983

물 또는 콘크리트반사체(反射體)의 두께 및 콘크리트반사체(反射體)와 핵물질용액계(核物質溶液系) 사이의 간격에 따라 변(變)하는 유효증배계수(有效增倍係數)로서의 반사효과(反射效果)를 중성자수송이론(中性子輸送理論)에 기초를 둔 각분할방법(角分割方法)의 전산코드 ANISN으로 계산하였다. 그 결과에 따르면 반사체(反射體)의 두께가 엷을 때, 유효증배계수(有效增倍係數)를 기준으로 한 물 반사체(反射體)의 반사효과(反射效果)는 콘크리트에서보다 크지만 그 두께가 커지면 반대현상도 생기는 것 같았다. 한편 핵물질용액계(核物質溶液系)와 콘크리트반사체(反射體)사이에 물이 채워져 있고 그 간격변화에 따라 산출한 유효증배계수치(有效增倍係數値)는 처음 급격하게 감소하다가 약 15cm를 지나면서부터 서서히 감소하는 것 같았다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.12-15
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• 2002

Korea Power System Protection Setting Rule was used from the rectify 1990's. Thereafter transmission voltage is raised the voltage into 765kV, and introduction to new technology of Power System, and was many of variation but, it is using. The present is using Digital type distance relay for 765kV transmission line protection. If impedance value of transmission line were to value lower than setting, this would be operating and relay setting rule is for 85% into Zone 1 self section, and Zone 2 is a 125%, Zone 3 is a 225%. Which's $15{\sim}25%$ include current transformer error 5%, potential transformer 5%, relay calculation error 5% and margin factor from the field experience. This paper is discussed transmission protective relay and relay setting rule of high voltage power system and we verify the correctness relay setting rule with distance relay using Matlab simulation.