• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1399-1411
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• 2012

The grid frequency is controlled cooperatively by the governor of the Turbine-Generator and the automatic generation controller(AGC) of the KPX(Korea Power Exchange). It is a basic requirement that the reliability of the governor is verified to enhance the power system stability but it is not easy to confirm the response characteristics of the governor because all generators are operated in the grid system that has the constant voltage and frequency. Therefore, it is necessary to study a new test method in order to examine the governor dynamic characteristic in the similar fault conditions. A study has shown that it is verified to simulate the turbine-generator power control system, the governor response characteristic under limited conditions and contribution of AGC with the gas turbine generator simulation model as well as demonstrate the dynamic response of the governor with the developed governor dynamic characteristic tester based on digital controller while the turbine-generator is connected to the grid system. This tester is constructed by the built-in functions of the turbine-generator main controller. In this treatise, the theoretical background, development method and the results of both simulations and demonstrations are described as another way to verify the turbine-generator governor dynamic characteristics.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1827-1834
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• 2016

This paper presents a high efficient generator with PM(Permanent Magnet) exciter. The proposed PM exciter for the generator can produce a linear output voltage according to the engine speed. This output voltage is directly used to control the field current of the generator to adjust the generator output voltage. In the proposed generator system, since the field winding current can be supplied by the PM exciter, the generator can self-start without any battery or an external power supply due to the low residential flux. Furthermore, the operating efficiency of the generator is higher than a conventional winding exciter. The main problem of the proposed generator system, the field winding current controller has to be embedded inside the generator, and it rotates according to the generator shaft. In this paper, the proper embedded current controller is designed for the proposed generator system. Due to the embedded controller cannot be connected to the outside the generator controller, the measured instantaneous output voltage of the generator is transferred by the photo isolated communication using shaft aligned infrared transmitter and receiver to keep the constant generator output voltage. In this paper, 10kW, 380V engine generator with PM exciter and the embedded DAVR(Digital Automatic Voltage Regulator) are described. The proposed high efficiency generator is simulated and tested to verify the effectiveness.

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.42-47
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• 2011

Automatic generation control (AGC) is an important function for load frequency control, which is being implemented in Energy Management System (EMS). A key feature of AGC is to back up governors to enhance the performance of frequency control. The governor regulates system frequency in several to ten seconds, while the droop control concept results in steady-state control error. AGC is a supplementary tool for compensation of the steady-state error caused by the droop setting of the governors. As the AGC target is delivered to each generator as an open loop control target, the generator output is not guaranteed to follow the AGC target. In this paper, we introduce generating unit controller (GUC) control block, which has the purpose of enabling the generator output to track the AGC target while maintaining the governor performance. We also address the tuning methods of GUC for better performance of AGC in the Korea Energy Management System (K-EMS).

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.792-795
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• 1999

Since the inception of fuzzy control, lots of methods to design fuzzy controller have been reported, However, it is admitted that these methods are tailored to special problems and cannot be used in general control situation. Therefore this paper proposes auromatic generation algorithm of fuzzy control system and develops an automatic fuzzy controller generator. For that purpose, the genetic algorithm is used and it searches for the optimal parameters to design the fuzzy controller

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.5
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• pp.1036-1042
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• 2011

This paper presents an algorithm that conducts automatic memory scrubbing operated by dedicated hardwares. The proposed algorithm is designed so that it can scrub entire memory in a given scrub period, while minimally affecting the execution of flight softwares. The scrub controller is constructed in a form of state machines, which have two execution modes - normal mode and burst mode. The deadline event generator and period tick generator are designed in a separate way to support the behavior of the scrub controller. The proposed controller is implemented in VHDL code to validate its applicability. A simple version of the controller is also applied to mass memory modules used in STSAT-3.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.85-90
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• 1996

In this paper, the self-organizing fuzzy logic controller is developed for water level control of steam generator. In comparison with conventional fuzzy logic controllers, this controller performs control task with no control rules at initial and creates control rules as control behavior goes on, and also modifies its control structure when uncertain disturbance is suspected. Selected parameters in the fuzzy logic controller are updated on-line by the gradient descent loaming algorithm based on the performance cost function. This control algorithm is applied to water level control of steam generator model developed by Lee, et al. The computer simulation results confirm good performance of this control algorithm in all power ranges. This control algorithm can be expected to be used for automatic control of feedwater control system in the nuclear power plant with digital instrumentation and control systems.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.151-156
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• 2002

The output voltage of Synchronous Generator is regulated constantly by field current control in excitation system. A synchronous generator is equipped with an automatic voltage regulator(AVR), which is responsible for keeping the constant output voltage under normal operating conditions about various levels. High frequency PWM converter (Current Mode Control Buck converter) type excitation system for synchronous generator is able to sustain output voltage level properly when the fault condition happened. This paper deals with the design and evaluation of the excitation system controller for a synchronous generator to improve the steady state and transient stability. The simulation and experimental results show that the proposed excitation system is improve the respons time by the AVR(automatic voltage regulator) of 50kW synchronous generator that is applied the current mode control excitation system.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1164-1166
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• 1996

This system is an unified Digital Generator Controller. It has an Electronical Generator Sequencer which control the sequence of a generator, an AVR(Automatic Voltage Regulator) which perform the regulation of generator terminal voltage optimally to user's needs, and an Auto Synchronizer, it can switch the power source on from generally used an the generator to load automatically. It also possesses a Battery Charger which charge a storage battery to appropriate voltage level. Here we describe it's configuration, specifications, the way of control, figure, functions and waveforms.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.397-403
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• 2009

In this paper, an exciter current control of a synchronous generator for ships using a compound type digital automatic voltage regulator (DVAR) in order to provide a constant output voltage of the generator is presented. The compound type DAVR is composed of a controller part to adjust output voltage and an power source unit to supply power to the exciter. The controller part, which generates the PWM switching pattern via the PI controller, drives a power MOSFET for bypass to limit the SG's exciter current. The power source unit part is parallel connected to an output terminal of the generator through a reactor and a power CT. The residual magnetic flux of SG provides exciter current to the exciter through the reactor during the initial running or no load state and load current supplies field current to the exciter through the power CT during loading state. This paper confirmed an experiment to verify the validity of compound type DAVR system for controlling output voltage of synchronous generator.

• Journal of Power Electronics
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• v.15 no.4
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• pp.861-875
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• 2015

This paper presents a wide frequency range LLC resonant controller IC for LED backlight units. In this paper a new phase-domain resonance deviation prevention circuit (RDPC), which covers a wide frequency and input voltage range, is proposed. In addition, a wide range gate clock generator and an automatic dead time generator are proposed. The chip is fabricated using 0.35 μm BCD technology. The die size is 2 x 2 mm2. The frequency of the clock generator ranges from 38 kHz to 400 kHz, and the dead time ranges from 300 ns to 2 μs. The current consumption of the LLC resonant controller IC is 4 mA for a 100 kHz operation frequency using a supply voltage of 15 V.