• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2303-2310
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• 2009

Defense systems are needed to prevent catastrophic failures of a power grid due to cascaded events. Cascaded events can be attributed to improper operations of protective relays. Especially, it is the most dangerous problem that trips of backup relays by overload. In this paper, a new algorithm of predicting Zone 3 acting time of distance relay is proposed using the real time synchronized data from PMUs on the transmission system when the power system is danger. In the proposed, some part of the power system are outage when some unexpected fault in the power system, the algorithm will monitor the impedance locus of distance relay. At this time, if there is a big change of Impedance locus, the algorithm will calculate the Zone 3 acting time of the distance relay by the over load. In the case studies, the estimation and simulation network have been testified and analysed in Matlab Simulink.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.2
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• pp.261-284
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• 2017

This paper describes the results of a low-frequency oscillation analysis using data measured in PMU installed in the KEPCO system, and the comparison with eigenvalues computed from the linear model. The dominant oscillation modes are estimated by applying various algorithms. The algorithms are: the extended Prony method; multiple time interval parameter estimation method; subspace system identification method; and spectral analysis. From the measurement data, modes of frequency 0.68[Hz] and 0.92[Hz] were estimated, and modes of frequency 0.63[Hz] and 0.80[Hz] were computed from the eigenvalue calculation. There was a difference between the mode estimated from measurement data and that from the linear model. This is possibly because of an error in the dynamic data of the KEPCO system used in eigenvalue calculation. Because wide area modes exist in the KEPCO system, these modes should be monitored continuously for the reliable operation of the system. In order to prevent total blackouts caused by wide area oscillation, moreover, contingency analysis should be performed in relation to this mode and appropriate measures should be established.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.4
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• pp.206-212
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• 2017

In this paper, using the power system information obtained from real-time monitoring device, to analyze the voltage stability margin index and described the voltage stability control scheme for voltage stability enhancement. Based on the utilization of the voltage stability monitoring index based on local information provided by the PMU(Phasor Measurement Unit), the purpose of the plan is to control the system stably in real time. In order to apply the load control scheme, the voltage stability margin is calculated using the data acquired through the PMU installed in each load bus. If the voltage drops below a certain level, load control is performed for each. The effectiveness of the voltage stability control measures is applied to the actual KEPCO system to analyze the effectiveness.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.173-174
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• 2006

The power infrastructure defense system monitor and control a power system with parameters of a power system such as voltage, phasor angle, frequency and power flow which are measured at the same instance. For this, synchronized phasor measurement based on the GPS(Global Positioning System) is necessary. PMU(Phasor Measurement Unit) measures synchrophasor and transmits it to the power infrastructure defense system. For this communication, IEEE H37.118 defines a communication message format and measurement concept and we extend the protocol to transmit disturbance data. The synchrophasor data can be sent at various rates and there are several options for phasor information sent in the synchrophasor message. In this paper, we develop software that simulate communication between the power infrastructure defense system and PMU to annalize the traffic.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.471-474
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• 2004

Not all CCD pixels generate uniform value for the uniform radiance due to the different process of manufacture and each pixel characteristics. And the image data compression is essential in the real time image transmission because of the high line rate and the limited RF bandwidth. This pixel's nonuniformity and the loss compression make CCD pixel correction necessary in on-orbit condition. In the MSC system, the NUC unit, which is a part of MSC PMU, is charge of the correction for CCD each pixel. The correction is performed with the gain and the offset table for the each pixel and the each TDI mode. These correction tables are generated and programmed in the PMU Flash memory through the various image data tests at the ground test. Besides, they can be uploaded from ground station after onorbit calibration. This paper describes the principle of the table generation and the test way of the non-uniformity after NUC

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1262-1266
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• 1999

More precise operation and control is required to ensure the stability and security of modern large power systems that is a complicated and widely dispersed structure. To ensure the precise operation and control of modern power system, most of all, precise monitoring and measurement of the various state values of power system is required. This paper discusses phasor measurement unit using synchronization signals from the GPS satellite system- Synchronized Phasor Measurement Unit. Considering the power system operation state, the transmitting data format over modems is defined. To provide all available information, PMU process the measurements to generate three phase symmetrical component. This paper proposes the transmitted data format and implements the PMU model using EMTP/Models. The validity of proposed model is confirmed through several contingency on the simple power system.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.92.6-92
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• 2001

MSC is being developed to be installed on KOMPSAT(Korea Multi-Purpose Satellite-II and to provide high resolution multi-spectral. MSC consists of three main subsystems. One is EOS(Electro-Optics Subsystem), another is PMU(Payload Management Unit) and the other is PDTS(Payload Data Transmission Subsystem). There is an SBC(Single Board Computer) in the PMU to control all MSC subsystems. SBC incorporates Intel 80486 as a main processor and VxWorks as a real-time operating system. SBC software consists of four main tasks and several modules to deal with all control information for imaging and all the state of health telemetrv data, and to perform interface with another MSC units. SBC software also has to handle a lot of commands in order for MSC to perform his mission. One mission command consists of a series of related commands, which are In be executed in the designated sequence, with a specified time ...

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.18-29
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• 2015

State Estimation (SE) is the basis of a variety of advanced applications used in most modern power systems. An SE problem formed with enough phasor measurement units (PMUs) data is simply a linear weighted least squares problem requiring no iterations. Thus, designing a minimum-cost placement of PMUs that guarantees observability of a power system becomes a worthy challenge. This paper proposes an equivalent integer linear programming method for substation-oriented optimal PMU placement (SOOPP). The proposed method uses an exhaustive search to determine a globally optimal solution representing the best PMU placement for that particular power system. To obtain a more comprehensive model, contingencies and the limitation of the number of PMU measurement channels are considered and embodied in the model as changes to the original constraints and as additional constraints. The proposed method is examined for applicability using the IEEE 14-bus, 118-bus and 300-bus test systems. The comparison between SOOPP results and results obtained by other methods reveals the excellence of SOOPP. Furthermore, practical large-scale power systems are also successfully analyzed using SOOPP.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1987-1988
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• 2011

국내외적으로 스마트그리드 구축을 위해 스마트미터, 센서, PMU(Phasor Measurement Unit) 및 IED(Intelligent Electronic Device) 등의 다양한 장치들이 전력시스템에 보급되고 있다. 스마트미터는 전력소비자의 전력사용량 뿐 아니라 다양한 계량 정보를 상위 수집시스템에 전달할 수 있는 기능을 갖추고 있으며, 계통에 설치된 여러 종류의 센서, PMU 및 IED들 또한 상위 감시제어시스템에 수많은 데이터를 제공한다. 이렇듯 스마트그리드 구축에 따른 스마트미터의 보급, 센서 및 IED의 확산에 따라 전력시스템에서 발생되는 방대한 데이터의 관리 문제와 어떻게 이들 데이터를 전력시스템 운영에 유용하게 활용할 수 있는가에 대한 문제들이 새롭게 부각되고 있다. 본 논문은 스마트그리드 구축에 따라 발생되는 수많은 데이터의 관리와 이들 데이터의 활용사례에 대하여 기술한다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.475-476
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• 2007

PMU로부터 전압, 전류 Phasor 정보를 실시간으로 취득하게 되면서 실시간으로 전압안정도를 감시하는 것이 가능하게 되었다. PMU 정보만을 이용하여 전압안정도를 감시하는 기술은 기존의 SCADA/EMS 데이터를 전혀 사용하지 않고도 매우 빠른 속도로 계통의 전압안정성을 판별해 낼 수 있다. 본 논문에서는 광역전압안정도를 감시하는 기술을 응용하여, 수도권 정보만을 사용하여 실시간으로 전압 안정도를 감시하는 방법을 제안하고자 한다. 기존의 방법보다 적은 수의 PMU를 필요로 하며, 대신에 계통데이터 중 선로임피던스를 필요로 한다. 본 방법을 검증하기 위하여 한전 실계통을 사용하도록 한다.