• Proceedings of the KIEE Conference
• /
• 2004.11c
• /
• pp.556-558
• /
• 2004

In this paper, we introduce a new method of detecting faults for a power converter unit in Control Rod Control System. The faults of a power converter unit can exert harmful influence upon the operation of Control Rod Drive Mechanisms and the control of the reactor output. This situation makes the quick and correct detection of failures in a power converter unit very important. We devise a new method of fault detection for the digital power controller and improve the drawbacks of the existing fault detector.

• Journal of Power Electronics
• /
• v.11 no.4
• /
• pp.490-498
• /
• 2011

This paper presents a novel analysis, design, and implementation of a battery charging three-phase high frequency semi-controlled power converter feasible for plug-in hybrid electric vehicles. The main advantages of the proposed topology include high efficiency; due to lower power losses and reduced number of switching elements, high output power density realization, and reduced passive component ratings proportionally to the frequency. Additional advantages also include grid economic utilization by insuring unity power factor operation under different possible conditions and robustness since short-circuit through a leg is not possible. A high but acceptable total harmonic distortion of the generator currents is introduced in the proposed topology which can be viewed as a minor disadvantage when compared to traditional boost rectifiers. A hysteresis control algorithm is proposed to achieve lower current harmonic distortion for the rectifier operation. The rectifier topology concept, the principle of operation, and control scheme are presented. Additionally, a dc-dc converter is also employed in the rectifier-battery connection. Test results on 50-kHz power converter system are presented and discussed to confirm the effectiveness of the proposed topology for PHEV applications.

• Proceedings of the KIPE Conference
• /
• 2005.07a
• /
• pp.329-332
• /
• 2005

Distributed generation (DG) systems fall in islanding operation when they still in operation even when the main grid is out of electric power Islanding operation is further classified into intentional islanding and unintentional islanding operations. In intentional islanding operation, the DG backs up critical loads while it separates from the main grid on islanding detection. Intentional islanding operation increases utilization of the DG system during the islanding operation. This paper proposes reasonal inverter topology and its control algorithm for seamless transfer of DG systems in intentional islanding operation.

• Journal of Industrial Technology
• /
• v.19
• /
• pp.217-226
• /
• 1999

A single phase to three phase power converter with cost effective and simple structure is proposed. The converter consists of rectifier and inverter. The rectifier is composed of a half wave rectifier, a dc link capacitor, and a current limiting inductor, and the inverter is of only two switches with PWM control. For negative sequence operation the inverter output voltage leads the line input by $60^{\circ}$, and for positive sequence operation the inverter output voltage leads by $60^{\circ}$. We can see that positive sequence operation shows higher output voltage, slight harmonic distortion(2%), and better performances such as high efficiency and high power factor. A mathematical model for system analysis is provided, and specifications for selection and control scheme both for start-up and for steady state are analyzed. comparison and operational limits of positive and negative sequence operation are performed, and simulations and experiments are executed to verify the proposed.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.63 no.2
• /
• pp.74-80
• /
• 2014

Generator protection device has to detects an internal fault conditions in generator and abnormal operating conditions must be due to the hazards. Loss of excitation may cause generator itself failure as well as serious operating problem in power system, and then requires an appropriate response of generator protection device. Details modeling of generator control system and analysis of transient states in generator are important for optimal operation in power plants. In addition, the fault simulation data are also used for testing the characteristics of IED. In this paper, the hydro generator control system using PSCAD/EMTDC, visual simulation for power systems, was modeled. The generator control system which is composed of generator, turbine, exciter, governor was implemented. The parameters of generator control system model were obtained from field power plant. Loss of excitation simulations were performed while varying the fixed load. Several signals analysis were also performed so as to analyze transients phenomena.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.54 no.12
• /
• pp.609-615
• /
• 2005

A 30kW electrical power conversion system is developed for a variable speed wind turbine. In the wind energy conversion system(WECS) a synchronous generator with field current excitation converts the mechanical energy into electrical energy. As the voltage and the frequency of the generator output vary according to the wind speed, a 6-bridge diode rectifier and a PWM boost chopper is utilized as an ac-dc converter maintaining the constant dc-link voltage with only single switch control. An input current control algorithm for maximum power generation during the variable speed operation is proposed without any usage of speed sensor. Grid connection type PWM inverter converts dc input power to ac output currents into the grid. The active power to the grid is controlled by q-axis current and the reactive power is controlled by d-axis current with appropriate decoupling. The phase angle of utility voltage is detected using software PLL(Phased Locked Loop) in d-q synchronous reference frame. Experimental results from the test of 30kW prototype wind turbine system show that the generator power can be controlled effectively during the variable speed operation without any speed sensor.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.60 no.4
• /
• pp.175-180
• /
• 2011

A large AC generator is an important component of the power system. It is a need for research of AC generator protection relay for the next-generation ECMS and an efficient operation of protection control system. However, most of protection and control systems used in power plants have been still imported as turn-key and operated in domestic. This may cause the lack of the correct understanding on the protection systems and methods, and thus have difficulties in optimal operation. In this paper, over-excitation protection relaying is one of the protective factors in generator protection IED was presented. The cause and protection principles were dealt and, DFT-based gain compensation algorithm was adopted for the frequency measurement. The Republic of Korea 345kV modeling data by EMTP-RV was used for performance evaluation.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.52 no.9
• /
• pp.500-505
• /
• 2003

The target of the ULTC(Under Load Tap Changer) control purpose is to minimize the operation number of the tap of the ULTC doing the error voltage which is the difference between the measured bus voltage End the reference bus voltage of the receiving end becomes less than the tolerance limits. The existing ULTC control method controls each ULTC considering only its bus voltage of the receiving end. However, this method did not cons der the coordinated control of the ULTCs of the system. In this paper, I proposed a coordinated control of the ULTC in :he loop power system using the Jacobian matrix. To show the validity of the proposed method, I made simulations for three cases: no action of the ULTC, the control of the ULTC by the existing control method, and the control of the ULTC by the coordinated control among the ULTCs of the system. The simulation result shows that the proposed method has more improvement of the operation of the ULTC than other methods.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.1225-1228
• /
• 1996

This paper describes the application area of the multimedia conference system for the electric power system operation. A variety of multimedia systems which are to be installed in the existing information communication network of KEPCO are introduced.

• Proceedings of the KIEE Conference
• /
• 2001.07a
• /
• pp.285-288
• /
• 2001

In this paper we proposed the on line volt/var control schemes of the load Tap Changer (LTC) transformer and shunt capacitor bank for distribution volt/var regulation. In the existing volt/var control of the distribution substation, the voltage of feeders and var of distribution systems is mainly controlled by the LTC transformer tap position and on/off status of the shunt capacitor. The LTC and shunt capacitor bank has discrete operation characteristics and therefore it is very difficult to control volt/var at the distribution networks within the satisfactory levels. Also there is limitation of the operation times of the LTC and shunt capacitor bank because it is affects on their functional lifetime. The proposed volt/var control algorithm determine an optimal tap position of LTC and on/off status of shunt capacitors at a distribution network with the multiple feeders. The mathematical equations of the proposed method are introduced. Simple case study was performed to verify the effectiveness of the proposed method.