• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.93_94
• /
• 2009

Load modeling has a significant impact on power system analysis and control. Estimating model parameters can be considered as important as stability analysis itself for accurate analysis and control. This paper presents a method for estimating parameters for load models, which include static and dynamic parts, based on particle swarm optimization. The method effectively searches a suitable set of parameters minimizing the fitness function. This paper applies the method to simulation data obtained from 8-bus test system including induction motors.

• Proceedings of the KIEE Conference
• /
• 1991.07a
• /
• pp.379-382
• /
• 1991

The dynamic characteristics and mathematical models of the KEPCO's generator control systems have been derived by on-line tests. Measuring the responses for small disturbances in the inputs, the parameters of governing systems, excitation systems, and power system stabilizers have been determined. An overview of the field tests, parameter identification, and model verification is presented.

• Proceedings of the KIPE Conference
• /
• 1999.07a
• /
• pp.76-79
• /
• 1999

A study on simulation using Matlab shows the dynamic condition of a beam on feed-back with encorder. A controller for rapid response interpreted the stability on simulation with pole-placement technique. The effect of response was considered feed-back gain. The result of feed-back is described that various feed-back coefficient shows stable controll systems. It would be expected each result according to controllers.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.53 no.3
• /
• pp.122-128
• /
• 2004

This paper presents a control approach for designing a fuzzy-PI controller for a synchronous generator excitation and SVC system. A combination of thyristor-controlled reactors and fixed capacitors(TCR-FC) type SVC is recognized as having the most flexible control and high speed response, which has been widely utilized in power systems, is considered and designed to improve the response of a synchronous generator, as well as controlling the system voltage. A Fuzzy-PI controller for SVC system was proposed in this paper. The PI gain parameters of the proposed Fuzzy-PI controller which is a special type of PI ones are self-tuned by fuzzy inference technique. It is natural that the fuzzy inference technique should be based on humans intuitions and empirical knowledge. Nonetheless, the conventional ones were not so. Therefore, In this paper, the fuzzy inference technique of PI gains using MMGM(Min Max Gravity Method) which is very similar to humans inference procedures, was presented and applied to the SVC system. The system dynamic responses are examined after applying all small disturbance condition.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.19 no.1
• /
• pp.65-76
• /
• 2024

With the recent activation of the offshore wind power industry, there has been a development of power plants with a scale exceeding 400MW, comparable to traditional thermal power plants. Renewable energy, characterized by intermittency depending on the energy source, is a prominent feature of modern renewable power generation facilities, which are structured based on controllable inverter technology. As the integration of renewable energy sources into the grid expands, the grid codes for power system connection are progressively becoming more defined, leading to active discussions and evaluations in this area. In this paper, we propose a method for selecting optimal reactive power compensation capacity when multiple offshore wind farms are integrated and connected through a shared interconnection facility to comply with grid codes. Based on the requirements of the grid code, we analyze the reactive power compensation and excessive stability of the 400MW wind power generation site under development in the southwest sea of Jeonbuk. This analysis involves constructing a generation site database using PSS/E (Power System Simulation for Engineering), incorporating turbine layouts and cable data. The study calculates reactive power due to charging current in internal and external network cables and determines the reactive power compensation capacity at the interconnection point. Additionally, static and dynamic stability assessments are conducted by integrating with the power system database.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.1
• /
• pp.124-133
• /
• 2017

In the current lighting market, LEDs that have a high luminous efficiency, a long life and consume less power have emerged as next generation lighting. Owing to various designs and sizes of LEDs, the production process of existing LEDs involves many tasks that require manual labor; hence, the assembly of LEDs necessitates manpower. Because of the use of manpower, the production costs of LEDs increases and production efficiency decreases. Recently, the assembly parts of LEDs have been standardized for minimizing manual labor, and an LED is developed as an LED panel. The automatic assembly system produces LED convergent lighting by assembling two LED panels and one diffusion cover. To increase the production efficiency of the LED convergent lighting module, it is important that the development of a feeder can continuously supply the LED panels is required, and whose design has sufficient stability. The automatic assembly system of the LED convergent lighting module consists of two feeders, which convey LED panels and diffusion covers to a main conveyor, which assembles the lifted panels and covers. In this study, structural analysis and fatigue life for forced loads on the conveyer line of the feeder in the process of lifting LED panels and diffusion covers of each feeder, is analyzed. In addition, the drive of the belt constituting the conveyor line of each feeder is simulated, and the dynamic characteristics of the belt is analyzed using the virtual engineering method.

• Journal of Power Electronics
• /
• v.18 no.6
• /
• pp.1780-1790
• /
• 2018

Voltage feed-forward control (VFFC) is widely used in LCL-type grid-tied inverters due to its advantages in terms of disturbance rejection performance and fast dynamic response. However, VFFC may worsen the stability of inverters under weak grid conditions. It is revealed in this paper that a large phase-lag in the low-frequency range is introduced by VFFC, which reduces the phase margin significantly and leads to instability. To address this problem, a novel virtual-impedance-based control, where a phase-lead is introduced into the low-frequency area to compensate for the phase lag caused by VFFC, is proposed to improve system stability. The proposed control is realized with a high-pass filter, without high-order-derivative components. It features easy implementation and good noise immunity. A detailed design procedure for the virtual impedance control is presented. Both theoretical analysis and experimental results verify the effectiveness of the control proposed.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.389-394
• /
• 2004

A Fuzzy Logic Sliding Mode Control or FLSMC for the uninterruptible power system (UPS) is presented, which is tracking a sinusoidal ac voltage with specified frequency and amplitude. The FLSMC algorithm combines feedforward strategy with the Variable Structure Control (VSC) or Sliding Mode Control (SMC) and fuzzy logic control. The control function is derived to guarantee the existence of a sliding mode. FLSMC has an advantage that the stability of FLSMC can be proved easily in terms of VSC. Furthermore, the rules of the proposed FLSMC are independent of the number of system state variables because the input of the suggested controller is fuzzy quantity sliding surface value. Hence the rules of the proposed FLSMC can be reduced. The simulation results illustrate that the purposed approach gives a significant improvement on the tracking performances. It has the small overshoot in the transient and the smaller chattering in the steady state than the conventional VSC. Moreover, its can achieve the requirements of robustness and can supply a high-quality voltage power source in the presence of plant parameter variations, external load disturbances and nonlinear dynamic interactions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.110-115
• /
• 2014

The nuclear power plant was launched by Kori unit 1 in 1978 years. Currently, 23 nuclear power plants have been operating in Korea since 1978 years. The localization was completed for most of the reactor facility from Hanbit(Youngkwang) unit 3&4. However, RCP(Reactor Coolant Pump) and MMIS(Man Machine Interface System) is an important technology that has been excluded from the scope of the technical transfer has been dependent on a specific overseas vendor. Recent success in RCP development through co-operation with government and industries. Developed RCP will be applied to Shin-Hanul unit 1&2 nuclear power plants. The RCP operates in high speed and high pressure condition and only rotating component in the NSSS(Nuclear Steam Supply System). Therefore, the problem of vibration has arisen caused by the hydraulic forces of the working fluid. These forces can influence on the stability characteristics for entire RCS(Reactor Coolant System) loop, and can act as significant destabilizing forces. In this study, vibration evaluation of the pump shaft of development RCP estimated under normal operation and over speed conditions. In order to predict the vibration characteristics and dynamic behavior, modal analysis, critical speed analysis and unbalance response spectrum analysis were performed.

• Journal of Power Electronics
• /
• v.19 no.6
• /
• pp.1527-1535
• /
• 2019

Because of the shortcomings of the PID controllers and traditional drive systems of permanent magnet synchronous motors (PMSMs), a PMSM passivity-based control (PBC) drive system based on a quasi-Z source matrix converter (QZMC) is proposed in this paper. The traditional matrix converter is a buck converter with a maximum voltage transmission ratio of only 0.866, which limits the performance of the driven motor. Therefore, in this paper a quasi-Z source circuit is added to the input side of the two-stage matrix converter (TSMC) and its working principle has also been verified. In addition, the controller of the speed loop and current loop in the conventional vector control of a PMSM is a PID controller. The PID controller has the problem since its parameters are difficult to adjust and its anti-interference capability is limited. As a result, a port controlled dissipative Hamiltonian model (PCHD) of a PMSM is established. Thereafter a passivity-based controller based on the interconnection and damping assignment (IDA) of a QZMC-PMSM is designed, and the stability of the equilibrium point is theoretically verified. Simulation and experimental results show that the designed PBC control system of a PMSM based on a QZMC can make the PMSM run stably at the rated speed. In addition, the system has strong robustness, as well as good dynamic and static performances.