• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2840-2851
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• 2022

Electric boilers (EBs) are the backup steam source for the auxiliary steam system of high-temperature gas-cooled reactor nuclear power plants. When the plant is in normal operations, the EB is always in hot standby status. However, the current hot standby operation strategy has problems of slow response, high power consumption, and long operation time. To solve these problems, this study focuses on the optimization of hot standby operations for the EB system. First, mathematical models of an electrode immersion EB and its accompanying deaerator were established. Then, a control simulation platform of the EB system was developed in MATLAB/Simulink implementing the established mathematical models and corresponding control systems. Finally, two optimization strategies for the EB hot standby operation were proposed, followed by dynamic simulations of the EB system transient from hot standby to normal operations. The results indicate that the proposed optimization strategies can significantly speed up the transient response of the EB system from hot standby to normal operations and reduce the power consumption in hot standby operations, improving the dynamic performance and economy of the system.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.3
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• pp.263-269
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• 2009

This paper describes comparative analysis results about the dynamic interaction of interconnected wind power system using the actual-size hardware simulator and the simulation model with PSCAD/EMTDC. The hardware simulator, which is composed of 2.0MVA induction motor with drive system and 1.5MW doubly-fed induction generator, was built and tested in Go-Chang Test Site of KEPCO for analyzing the dynamic interaction with the interconnected distribution system. The operation of hardware simulator was verified through comparative analysis between experimental results and simulation results obtained by simulation model with PSCAD/EMTDC. The developed hardware simulator and simulation model could be effectively used for analyzing the dynamic interaction, which has various phenomena depending on the wind variation and the network state of interconnected power system.

• Proceedings of the KIEE Conference
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• summer
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• pp.224-226
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• 2004

Flexible AC Transmission System (FACTS) can greatly reinforce power systems through improvement of power transmission capacity and utilization of equipment under the circumstance of continuous load growth and deregulation SVC and STATCOM are shunt FACT devices that have similar static characteristics with Mwhuical Swikhed Capacitor (MSC). The main issue of this paper is the analysis of different dynamic characteristics when STATCOM is solely adopted and when STATCOM is adopted with combination of other reactive power compensator such as SVC and M5C. Furthermore, better application of reactive power compensators can be clarified through analysis of dynamic characteristics of various combinations of reactive power compensators.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.6
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• pp.56-62
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• 2009

Inexpensive high performance computer systems combined with high speed networks and machine independent communication libraries have made cluster computing a viable option for parallel applications. In a heterogeneous cluster environment, efficient resource management is critically important since the computing power of the individual computer system is a significant performance factor when executing applications in parallel. This paper presents a dynamic task manager, called DWM (dynamic work manager). It makes a heterogeneous cluster system fully utilize the different computing power of its individual computer system. We measure the performance of DWM in a heterogeneous cluster environment with several kernel-level benchmark programs and their programming complexity quantitatively. From the experiments, we found that DWM provides competitive performance with a notable reduction in programming effort.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.165-167
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• 2007

This paper presents a analysis method for power system stability using a Modified Genetic-based Power System Stabilized(MGPSS). The proposed MGPSS parameters are optimized using Modified Genetic Algorithm(MGA) in order to maintain optimal operation of generator under the various operating conditions. To improve the convergence characteristics, real variable string is adopted. The results tested on a single machine infinite bus system verify that the proposed controller has better dynamic performance than conventional controller.

• Progress in Superconductivity and Cryogenics
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• v.15 no.1
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• pp.19-24
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• 2013

In this paper, the Superconductor flywheel energy storage system (SFESS) was used for the load frequency control (LFC) of an interconnected 2 area power system. The robust SFESS controller using quantitative feedback theory (QFT) was designed to improve control performance in spite of parameter uncertainty and unexpected disturbances. An overlapping decomposition method was applied to simplify SFESS controller design for the interconnected 2 area power system. The model for simulation of the interconnected 2 area power system included the reheat steam turbine, governor, boiler dynamics and nonlinearity such as governor deadband and generation rate constraint (GRC). To verify robust performance of proposed SFESS controller, dynamic simulation was performed under various disturbances and parameters variation of power system. The results showed that the proposed SFESS controller was more robust than the conventional method.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.1
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• pp.57-66
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• 2012

This paper proposes a performance improvement of grid-connected inverter system using sliding-mode based direct power control with a variable gain. The proposed control method determine variable gain of PI controller by using modeling at direct power control (DPC) applied to space vector modulation method. Also, this method use sliding-mode control to maintain excellent dynamic response of character of direct power control (DPC). The validity of the proposed algorithm are verified by simulations and experiments.

• Journal of Power Electronics
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• v.11 no.5
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• pp.704-712
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• 2011

This paper describes a hybrid induction motor drive system incorporating DTC-hysteresis and Direct Self Control (DSC) schemes to achieve excellent dynamic performance. The control scheme is switched from a circular to a hexagonal flux locus whenever a dynamic condition is encountered. On the other hand, when the motor operates under steady state conditions, a circular flux locus is used. Without major modifications to the simple structure of a basic DTC, hexagonal flux locus operation is established by modifying the flux error status, before it is fed to the look-up table. The feasibility of the proposed hybrid scheme to achieve excellent control performance is verified by experimental results.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.348-350
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• 2003

In recent years, with the continuous development of modem power system, the need for high performance protection to meet the customers' requests for more stable and reliable power supply has become increasingly emphasized. So, there is urgent need for a proper testing platform about not only existing digital protection relay but also new digital protection relay on the transmission line. It is also dynamic-state test which can test the performance of digital relay. This paper suggests basic system model for testing transmission line protection using PSCAD/EMTDC, and presents the process of the component modeling in the basic system.

• Journal of Power System Engineering
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• v.6 no.3
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• pp.71-77
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• 2002

In this study, a dynamic model of proportional pressure control valve using the bond graph and a predictive controller are presented in the form of dynamic matrix control which is concerned with a design method of digital controller for the electro hydraulic servo system. The bond graph can be utilized for all types of systems which involve power and energy, and it is applied to a propotional pressure control valve in this study. Recently, many researchers suggested that better control performance could be obtained by means of the predictive controls with future reference input, future control output and future control error. The Predictive controller is very practical because the controller can be easily applicable to a personal computer or a microprocessor. This study investigates through numerical simulations that hydraulic system with the predictive controller shows very good control performances.