• 한국산업융합학회 논문집
• /
• 제4권2호
• /
• pp.133-139
• /
• 2001

The nonlinear response statistics of an spring-pendulum system with internal resonance under narrow band random excitation is investigated analytically- The center frequency of the filtered excitation is selected to be close to natural frequency of directly excited spring mode. The Fokker-Planck equations is used to generate a general first-order differential equation in the dynamic moment of response coordinates. By means of the Gaussian closure method the dynamic moment equations for the random responses of the system are reduced to a system of autonomous ordinary differential equations. The nonlinear phenomena, such as jump and multiple solutions, under narrow band random excitation were found by Gaussian closure method.

• Journal of Power Electronics
• /
• 제19권3호
• /
• pp.761-770
• /
• 2019

This paper proposes a hybrid phase windings excitation method for improving the efficiency of a 7-phase brushless DC (BLDC) motor in the electric propulsion system of a ship. The electrical losses of a BLDC motor system depend on the operating region and the number of excited phase windings (2-phase, 4-phase or general 6-phase windings). In this paper the operating region and torque/speed characteristics according to the motor rotation speed and propeller load are analyzed for a number of excitation methods. In addition, it analyzes the electrical losses of the system under each of the excitation methods in the entire operating region of the motor. In every sampling time, the proposed control method calculates the electrical loss of the system for each of the excitation methods and operates a 7-phase BLDC motor by selecting the excitation method that results a decreased electrical loss at the operating speed. The usefulness of the proposed control algorithm is verified through experimental results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
• /
• pp.416-418
• /
• 1997

Stable power source and fast control response are important for the generator excitation system. To stabilize the control of excitation circuit the PI controller for excitation current has been used. But the response of the system with this conventional control technique is very poor, especially in transient response with a predictive current control, the response of the excitation system can be improved. In this study, it is verified by the PSIM simulation.

• 조명전기설비학회논문지
• /
• 제17권3호
• /
• pp.32-39
• /
• 2003

동기발전기 출력전압은 여자시스템의 계자전류 제어에 의해 일정하게 유지된다. 고주파 PWM 컨버터(전류제어 모드 buck 컨버터) 형태의 여자시스템은 부하변동이 발생하였을 때 동기발전기의 계자전류를 제어하게 된다. 이 논문은 정상상태 및 과도상태에서의 안정화를 개선하기 위하여 여자시스템의 설계 및 실험에 대해 다루었다. 시뮬레이션 및 실험 결과는 제안된 여자시스템이 50[kW] 동기발전기의 DVR에 의해 응답시간이 개선되었음을 보여주었다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 하계학술대회 논문집 F
• /
• pp.2184-2186
• /
• 1997

Potential-source controlled rectifier excitation system has been developed by KEPRI for synchronous generator in YOUNG-DONG thermal power plant. This paper describes the characteristics of redundant control system and transfer function of dual channel excitation control system. This system has been using a analog and digital circuit devices(hybrid type)

• Journal of Electrical Engineering and Technology
• /
• 제13권4호
• /
• pp.1474-1482
• /
• 2018

As an essential means of generator voltage regulation, excitation control plays an important role in controlling the stability of the power system. Therefore, the reasonable design of an excitation controller can help improve the system stability. In order to raise the robustness of the generator exciting system under outside interference and parametric perturbation and eliminate chattering in the sliding mode control, this paper presents a generator excitation control based on the quasi-sliding mode pseudo-variable structure control. A mathematical model of the synchronous generator is established by selecting its power, speed and voltage deviation as state variables. Then, according to the existing conditions of the quasi-sliding mode, a quasi-sliding mode pseudo-variable structure controller is designed, and the parameters of the controller are obtained with the method of pole configuration. Simulations show that compared with the existing methods, the proposed method is not only useful for accurate voltage regulation, but also beneficial to improving the robustness of the system at a time when perturbance happens in the system.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
• /
• pp.237-239
• /
• 2006

Nowadays the core control systems are made by multiple redundancy strategy. There are analog excitation systems which have been operating during more than twenty years. This project is aim to retrofit nuclear power plants, also improves the reliance, safety, faculty of nuclear generator excitation system.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
• /
• pp.218-223
• /
• 2007

This paper presents a simple, robust excitation control system for synchronous generator using direct instantaneous voltage control(DIVC) method. The proposed DIVC excitation system can operate as high dynamics of power conversion system without any control gains such as Pill controller. And the transient overshoot of generator voltage can be suppressed with a simple time constant. For the continuous control of excitation system, the fast IGBT inverter system is used in this paper for exciter's field control. The proposed control scheme is verified by the computer simulations and experimental results in the prototype generation system.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.1170-1173
• /
• 2003

In the semiconductor and the optical industry a new transport system which can replace the common system is required. The common systems are driven by magnetic field and conveyer belt. The magnetic field damages semiconductor and contact force scratches, the optical lens. The ultrasonic wave driven system solve these problem. In this paper the object transport system using the excitation of ultrasonic wave is proposed. the experiments for finding the optimal excitation frequency, finding phase-difference between two ultrasonic wave generators are performed. The effect of transporting speed according to the change of amplification voltage is verified. In addition, the system performance for actual use is evaluated

• 전기학회논문지P
• /
• 제63권2호
• /
• 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.