• KIEE International Transactions on Power Engineering
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• 제4A권1호
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• pp.26-32
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• 2004

Digital technology has advanced significantly over the years both in terms of software tools and hardware availability. It is now applied extensively throughout many area of electrical engineering including protective relaying in power systems. Digital relays have numerous advantages over traditional analog relays, such as the ability to accomplish what is difficult or impossible using analog relays. Although non real-time simulators like PSCAD/EMTDC are employed to test the algorithms, such simulations are disadvantaged in that they cannot test the relay dynamically. Hence, real-time simulators like RTDS are used. However, the latter requires large space and is very expensive. This paper uses EMTP MODELS to simulate the power system and the distance relay. The distance relay algorithm is implemented and the distance relay is interfaced with a test power system. The distance relay's performance is then assessed interactively under various fault types, fault distances and fault inception angles. The test results show that we can simulate the distance relay effectively and we can examine the operation of the distance relay very closely including its drawbacks/limitations by using EMTP MODELS. Equally important, this approach facilitates any changes that need to be carried out in order to enhance the Distance Relay under test/examination.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.730-737
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• 2004

In this paper, in order to examine cyclic hehavior characteristics and safety of underground flexible pipes for electric cables subject to cyclic vehicle load, FEM analysis and cyclic soil box test were carried out. As results of the test, it was revealed that the vertical displacement of the test was larger than that of FEM analysis because thermal effect arising from power cables made reduction of rigidity of the pipe so that large deformation of the pipe induced by the heat occured. Moreover, it was shown that the final vertical displacement under about 0.4 million times of the cyclic load test was not satisfied with elastic allowable displacement of the pipe, and long term stability of the pipe was not stable since behavior characteristics of the pipe exists plastic strain range pasted clastic strain range.

• 조명전기설비학회논문지
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• 제23권7호
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• pp.67-74
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• 2009

This paper describes the speed control functions of the typical steam turbine speed controllers and the test results of generator load rejection simulations. The goal of the test is to verify the speed controller's ability to limit the steam turbine's peak speed within a predetermined level in the event of generator load loss. During normal operations, the balance between the driving force of the steam turbine and the braking force of the generator load is maintained and the speed of the turbine-generator is constant. Upon the generator's load loss, in other word, the load rejection, the turbine speed would rapidly increase up to the peak speed at a fast acceleration rate. It is required that the speed controller has the ability to limit the peak speed below the overspeed trip point, which is typically 110[%] of rated speed. If an actual load rejection occurs, a substantial amount of stresses will be applied to the turbine as well as other equipments, In order to avoid this unwanted situation, not an actual test but the other method is necessary. We are currently developing the turbine control system for another nuclear power plant and have plan to do the simulation suggested in this paper.

• Nuclear Engineering and Technology
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• 제33권4호
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• pp.441-456
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• 2001

ABB-CE＇s regionalization methodology for the core inlet flow distribution map is reviewed. This methodology merges the test data of fuel assembly locations which are either in symmetry or strongly correlated with others. It increases the number of available test data for each regional flow factor It makes up effectively for the deficiency due to limited number of test data. It also contributes to making the core inlet flow distribution smoother not only locally but also over the entire core, and to relieving the impacts of test errors that may happen due to some do- calibrated local pressure measurement taps. As a result, the core inlet How distribution data becomes more statistically useful and thus the conservatism involved in handling the core inlet flow factors for the thermal margin analysis is expected to be reduced. Meanwhile, the regionalized map may lose the unique local characteristics in core inlet flow distribution too much. By an alternative approach introduced in the present work, it is shown that such a disadvantage can be mitigated somewhat if the engineering judgement is made more

• 드라이브 ㆍ 컨트롤
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• 제21권1호
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• pp.16-21
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• 2024

The yaw gearbox is a key device in a wind power generator that improves power generation efficiency by rotating hundreds of tons (400 to 600 tons) of nacelle so that the blade reaches 90 degrees in the wind direction. Recently, installation sites have been advancing from land to sea as they have become super-large at (8-12) MW to increase the economic feasibility of wind power generators and utilize excellent wind resources, and the target life of large wind power generators is 25 to 30 years. The yaw gearbox of 6 to 12 sets is installed in a very complex place inside the nacelle on the tower with parallels, and it is important to secure the reliability of the yaw gearbox because if a failure occurs after installation, it costs tens to hundreds of times the price of a new product to restore. In this study, equivalent loads were calculated by analyzing failure mode and field data, accelerated life test conditions were established, and a test device was constructed to perform the accelerated life tests and performance tests to ensure the reliability of the gearbox.

• Journal of the Korean Statistical Society
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• 제26권4호
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• pp.453-465
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• 1997

The family of power-divergence statistics conditional on margins is considered for testing homogeneity of .tau. multinomial populations with equal sample size and the exact Bahadur slope is obtained. It is shown that the likelihood ratio test conditional on margins is the most Bahadur efficient among the family of power-divergence statistics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1373-1375
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• 1994

We now expect the various dispersed generation system installation to the power distribution system in a unexpected manner. If so, the power utility may experience the several unexpected problems such as voltage variation, harmonic distortion etc. In order to test the various phenomena related to the fault, we developed the fuel cell simulator and fault simulator. Several kinds of fault cases are tried. Test results and analysis are shown in this paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.11-12
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• 2007

In order to verify a digital substation based on IEC 61850, KEPRI in charge of POWER IT project related to SAS has constructed IED conformance testing system, which consists of HMI, IED (Intelligent Electronic Device), network equipment, V/I generator, and performed the interoperability test between two IEDs made by other vendors. The test was proceeded based on SCL and with system integrated tools

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.495-496
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• 2007

An Over Current Relayng algorithm using 80c196kc micro processor was realized in this paper. This OCR Algorithm was verified with simulated fault signal. The fault signal was made by EMTP and realized by DOBLE to compare H/W test with S/W test. This simulations showed similar result between H/W and S/W test.

• 한국태양에너지학회 논문집
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• 제34권4호
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• pp.1-7
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• 2014

The microgrid system is the combination of photovoltaic(PV) array, load, and battery energy storage system. The control strategies were defined as multi-modes of operation, including rest operation without use of battery, power charging, and power discharging, which enables grid connected mode or islanded mode. Photovoltaic power is a problem of the uniformity of power quality because the power generated from solar light is very sensitive to variation of insolation and duration of sunshine. As a solution to the above problem, energy storage system(ESS) is considered generally. There fore, in this study, we did basic research activities about optimization method of the amount of energy used, using a smart microgrid test-bed constructed in building. First, we analyzed the daily, monthly and period energy pattern amount of power energy used, and analyzed PV power generation level which is built on the roof. Utilizing building energy pattern analysis data, we was studied an efficient method of employing the ESS about building power consumption pattern and PV generation.