• Korean Chemical Engineering Research
• /
• v.46 no.2
• /
• pp.383-388
• /
• 2008

The safe and efficient operation of the chemical processes has become one of the primary concerns of chemical companies, and a variety of fault diagnosis methods have been developed to diagnose faults when abnormal situations arise. Recently, many research efforts have focused on fault diagnosis methods based on quantitative history data-based methods such as statistical models. However, when the history data-based models trained with the data obtained on an operation mode are applied to another operating condition, the models can make continuous wrong diagnosis, and have limits to be applied to real chemical processes with various operation modes. In order to classify operation modes of chemical processes, this study considers three multivariate models of Euclidean distance, FDA (Fisher's Discriminant Analysis), and PCA (principal component analysis), and integrates them with process dynamics to lead dynamic Euclidean distance, dynamic FDA, and dynamic PCA. A case study of the TE (Tennessee Eastman) process having six operation modes illustrates the conclusion that dynamic PCA model shows the best classification performance.

• Current Optics and Photonics
• /
• v.4 no.3
• /
• pp.186-192
• /
• 2020

This paper describes a real-time monitoring system in Ethernet passive optical networks (EPON) that uses burst-mode fiber Bragg grating (FBG) optical sensors. The FBG interrogation unit in the optical line terminal (OLT) transmits the monitoring wavelength to optical network units (ONUs). The FBG sensor unit in each ONU returns a burst-mode monitoring signal to the OLT. As the system applies time division multiple access (TDMA), a uniform Bragg wavelength can be used to monitor the EPON system. The FBG interrogation unit analyzes the received burst-mode monitoring signals and outputs fault information on the ONU branches in EPON. The simulation results show the effectiveness of the proposed monitoring system based on TDMA. In addition, we compared the proposed TDMA-based monitoring system with a WDMA-based monitoring system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.2
• /
• pp.201-207
• /
• 2013

This paper propose seamless transfer operation between grid-connected and stand-alone mode in the three-phase inverter for microgrid. The inverter operates grid-connected mode and stand-alone mode. Grid-connected mode is the inverter connected to grid and stand-alone mode is to deliver energy to the load from inverter at grid fault. When conversion from gird-connected to stand-alone mode, the inverter changes current control to voltage control. When grid restored, the inverter system is conversion from stand-alone to grid-connected mode. In this case, load phase and grid phase are different. Therefore, synchronization is essential. Thus Seamless transfer operation stand-alone to grid-connected mode. In this paper, propose sealmless transfer operation between grid-connceted and stand-alome mode, and this method is verified through simulation and experiment.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1853-1856
• /
• 2003

This paper considers the problem of longitudinal control of a platoon of automotive vehicles on a straight lane of a highway and proposes control laws in the event of loss of communication between the lead vehicle and the other vehicles in the platoon. Since safety plays a key role in the development of an Automated Highway System, fault-tolerant control is vital. In this paper, we develop a control algorithm in vehicle platooning and prove that this control algorithm is stable for certain class of faults such as parameter uncertainties. The performance of the controller is demonstrated through a series of simulations incorporating various vehicles and AHS faults. Results of simulation shows that the vehicles have good performance in spite of simple automotive and AHS failure, such as actuator failure,that is to say, engine input failure, communication failure between lead vehicle and the another vehicles.

• Journal of Industrial Technology
• /
• v.22 no.A
• /
• pp.29-36
• /
• 2002

A damage detection algorithm using vibration modes is applied to the ring structures and the modal behaviors of the slightly asymmetric rings are examined. Mode shape change, MSER(modal strain energy ratio) and MCR(modal curvature ratio) are investigated to identify the locations of faults or damages The above fault detection parameters are calculated and compared by the finite element analysis on rings with designed local damages. Damages are modeled as a reduced stiffness in the analysis The results show that MSER and MCR can be proper parameters to detect local damages in the ring structures.

• Proceedings of the KIEE Conference
• /
• 2005.05a
• /
• pp.81-83
• /
• 2005

The Reactor Protection System (RPS) is a very important system in a nuclear power plant because the system shuts down the reactor to maintain the reactor core integrity and the reactor coolant system pressure boundary if the plant conditions approach the specified safety limits. This paper describes the unavailability assessment of a digital reactor protection system using the fault tree analysis technique. The fault tree technique can be expressed in terms of combinations of the basic event failures. In this paper, a prediction method of the hardware failure rate is suggested for a digital reactor protection system. and applied to the reactor protection system being developed in Korea.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.10
• /
• pp.1259-1263
• /
• 1999

In this paper, a method to guarantee system continuity is developed, which can be applied to discontinuity problem in the time domain of restructurable control system. This method can be summarized as input alternation using weight change considering convergence speed of system mode. Input is changed from 'system continuity guarantee input,' which is defined as a input that minimizes the change of state variables, to 'alternative controller input,' which is selected by Neil's PI/EAM[3]. AIDC aircraft model is used for simulation. By showing the waveform of system input and state variable, we can sure that this method is effective for depression of system shock like jerk.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.563-564
• /
• 2015

Recently, distributed generation using renewable energy resources have increased due to the limitation of conventional energy. To utilize these energy source effectively, a method of applying the energy storage system(ESS) in distribution system has been considered. In this paper, we simulated the one line-to-ground fault in power system with ESS. Based on these simulations, we analyzed the effect on Over Current Relay(OCR) operation. As a result, ESS operation modes result fault current fluctuation. Thus, OCR need to reset the pick up current. This paper analyze effect of ESS in distribution system according to OCR setting by using ElectroMagnetic Transient Program(EMTP).

• Journal of Electrical Engineering and Technology
• /
• v.13 no.1
• /
• pp.78-88
• /
• 2018

The liberalization of electricity market and environmental concerns are the major driving forces for the development of Distributed Generation (DG). The mode of grid-connected wind power generation is becoming popular and has matured as a reliable DG technology. The voltage generated by the wind generator is stepped up to the higher voltage by the transformers before connecting to the grid. Operating algorithm of the differential relays for transformer protection used in the wind farms need to be modified to take care of the dynamic nature of fault current caused by the intermittent nature of the wind power. An algorithm for the differential relay is proposed in which dual slope characteristics are adjusted with varying fault level situation according to the wind generator in service as well as with the wind speed. A case study conducted for a typical wind farm shows that the proposed method avoids mal-operation of the differential relay in varying wind power conditions.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.7
• /
• pp.928-936
• /
• 2012

The microgrid concept assumes a cluster of loads and microsources operating as a single controllable system that provides a new paradigm for defining the operation of distributed generation. This system can be operated as both grid-connected mode and islanded mode. In other words, the microgrid can be operated to meet their special need; such as economics in steady state and local reliability in islanded mode due to the grid fault. This paper presents the AGC (Automatic Generation Control) method for microgrid with EMS (Energy Management System).