• Title/Summary/Keyword: dynamic parameters

Search Result 3,972, Processing Time 0.036 seconds

A Study on Damping Improvement of a Synchronous Generator with Static VAR Compensator using a Fuzzy-PI Controller (퍼지-PI 제어기를 이용하여 정지형 무효전력 보상기를 포함한 동기 발전기의 안정도 개선에 관한 연구)

  • 주석민;허동렬;김상효;정동일;정형환
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.15 no.3
    • /
    • pp.57-66
    • /
    • 2001
  • This paper resents 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 must fiexible 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 barred 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 allied to the SVC system. The system dynamic responses are examined after applying all small disturbance condition.

  • PDF

Comparative Study of PI, FNN and ALM-FNN for High Control of Induction Motor Drive (유도전동기 드라이브의 고성능 제어를 위한 PI, FNN 및 ALM-FNN 제어기의 비교연구)

  • Kang, Sung-Jun;Ko, Jae-Sub;Choi, Jung-Sik;Jang, Mi-Geum;Back, Jung-Woo;Chung, Dong-Hwa
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
    • /
    • 2009.05a
    • /
    • pp.408-411
    • /
    • 2009
  • In this paper, conventional PI, fuzzy neural network(FNN) and adaptive teaming mechanism(ALM)-FNN for rotor field oriented controlled(RFOC) induction motor are studied comparatively. The widely used control theory based design of PI family controllers fails to perform satisfactorily under parameter variation nonlinear or load disturbance. In high performance applications, it is useful to automatically extract the complex relation that represent the drive behaviour. The use of learning through example algorithms can be a powerful tool for automatic modelling variable speed drives. They can automatically extract a functional relationship representative of the drive behavior. These methods present some advantages over the classical ones since they do not rely on the precise knowledge of mathematical models and parameters. Comparative study of PI, FNN and ALM-FNN are carried out from various aspects which is dynamic performance, steady-state accuracy, parameter robustness and complementation etc. To have a clear view of the three techniques, a RFOC system based on a three level neutral point clamped inverter-fed induction motor drive is established in this paper. Each of the three control technique: PI, FNN and ALM-FNN, are used in the outer loops for rotor speed. The merit and drawbacks of each method are summarized in the conclusion part, which may a guideline for industry application.

  • PDF

Production properties of pyrolytic matter of PP and PS plastics in n low temperature pyrolysis condition (저온 열분해조건에서 PP 및 PS계 플라스틱의 열분해물 생성특성 연구)

  • Kim, Sang-Hoon;Jang, Hyun-Tae;Cha, Wang-Seog
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.8 no.4
    • /
    • pp.867-873
    • /
    • 2007
  • Thermal degradation characteristics of polypropylene and polystyrene have been studied in the thermogravimetric(TG) reactor and batch-type microreactor. The dynamic thermogravimetric curve of TG provided a valuable information about pyrolysis temperature. It was found that PS was thermally degraded at lower temperature of $30{\sim}50^{\circ}C$ than PP. It was found that the yield and molecular weight of liquid product in the microreactor were decreased with the increase of reaction temperature and time in the case of PP. The production of styrene monomer was significantly increased by the promotion of depolymerization with the increase of temperature and time. The chain-end scission rate parameters were determined to be 50.0 kcal/mole of PP, 45.2 kcal/mole of PS by the Arrhenius plot.

  • PDF

3-D Configuration Effects of Prestressing Cable Bracing Used for Retrofitting a RC Frame Subjected to Seismic Damage (RC 골조의 내진 보강을 위한 예압 가새의 3-D 배치)

  • Lee, Jin-Ho;Oh, Sang-Gyun;Hisham, El-Ganzori
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.7 no.3
    • /
    • pp.183-191
    • /
    • 2003
  • A four-story reinforced concrete moment resisting frame damaged from an ultimate limit state earthquake is upgraded with prestressing cable bracing. The purpose of this study is to investigate the bracing configuration effects on the 3-D building response using thee different locations of the bracing systems for the retrofitted building. Since the previous work done by the author proved that static incremental loads to collapse analysis as a substitute to dynamic non-linear time history analysis was a valid alternative tool. Thus, static load to collapse analysis is solely applied to evaluate the seismic performance parameters of both the original and upgraded buildings in this study. In results, the exterior bracing system is effective in restraining torsional behavior of the structure under seismic loads, and no sudden failure occurs in this system that enhances the ductility of the building due to the gradual change of building stiffness as the lateral load increases.

The Design of Auto Tuning Neuro-Fuzzy PID Controller Based Neural Network (신경회로망 기반 자동 동조 뉴로-퍼지 PID 제어기 설계)

  • Kim, Young-Sik;Lee, Chang-Goo
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.7 no.5
    • /
    • pp.830-836
    • /
    • 2006
  • In this paper described an auto tuning neuro-fuzzy PID controller based neural network. The PID type controller has been widely used in industrial application due to its simply control structure, easy of design, and inexpensive cost. However, control performance of the PID type controller suffers greatly from high uncertainty and nonlinearity of the system, large disturbances and so on. In this paper will design to take advantage of neural network fuzzy theory and pid controller auto toning technique. The value of initial scaling factors of the proposed controller were determined on the basis of the conventional PID controller parameters tuning methods and then they were adjusted by using neural network control techniques. This controller simple structure and computational complexity are less, and also application is easy and performance is excellent in system that is strong and has nonlinearity to system dynamic behaviour change or disturbance. Finally, the proposed auto tuning neuro-fuzzy controller is applied to magnetic levitation. Simulation results demonstrated that the control performance of the proposed controller is better than that of the conventional controller.

  • PDF

Development of a Time-Domain Simulation Tool for Offshore Wind Farms

  • Kim, Hyungyu;Kim, Kwansoo;Paek, Insu;Yoo, Neungsoo
    • Journal of Power Electronics
    • /
    • v.15 no.4
    • /
    • pp.1047-1053
    • /
    • 2015
  • A time-domain simulation tool to predict the dynamic power output of wind turbines in an offshore wind farm was developed in this study. A wind turbine model consisting of first or second order transfer functions of various wind turbine elements was combined with the Ainslie's eddy viscosity wake model to construct the simulation tool. The wind turbine model also includes an aerodynamic model that is a look up table of power and thrust coefficients with respect to the tip speed ratio and pitch angle of the wind turbine obtained by a commercial multi-body dynamics simulation tool. The wake model includes algorithms of superposition of multiple wakes and propagation based on Taylor's frozen turbulence assumption. Torque and pitch control algorithms were implemented in the simulation tool to perform max-Cp and power regulation control of the wind turbines. The simulation tool calculates wind speeds in the two-dimensional domain of the wind farm at the hub height of the wind turbines and yields power outputs from individual wind turbines. The NREL 5MW reference wind turbine was targeted as a wind turbine to obtain parameters for the simulation. To validate the simulation tool, a Danish offshore wind farm with 80 wind turbines was modelled and used to predict the power from the wind farm. A comparison of the prediction with the measured values available in literature showed that the results from the simulation program were fairly close to the measured results in literature except when the wind turbines are congruent with the wind direction.

Efficient Route Determination Technique in LBS System

  • Kim, Sung-Soo;Kim, Kwang-Soo;Kim, Jae-Chul;Lee, Jong-Hun
    • Proceedings of the KSRS Conference
    • /
    • 2003.11a
    • /
    • pp.843-845
    • /
    • 2003
  • Shortest Path Problems are among the most studied network flow optimization problems, with interesting applications in various fields. One such field is the route determination service, where various kinds of shortest path problems need to be solved in location-based service. Our research aim is to propose a route technique in real-time locationbased service (LBS) environments according to user’s route preferences such as shortest, fastest, easiest and so on. Turn costs modeling and computation are important procedures in route planning. There are major two kinds of cost parameters in route planning. One is static cost parameter which can be pre-computed such as distance and number of traffic-lane. The other is dynamic cost parameter which can be computed in run-time such as number of turns and risk of congestion. In this paper, we propose a new cost modeling method for turn costs which are traditionally attached to edges in a graph. Our proposed route determination technique also has an advantage that can provide service interoperability by implementing XML web service for the OpenLS route determination service specification. In addition to, describing the details of our shortest path algorithms, we present a location-based service system by using proposed routing algorithms.

  • PDF

Flexural-Torsional Free Vibrations of Circular Strip Foundation with Variable Breadth on Pasternak Soil (Pasternak지반으로 지지된 변화폭 원호형 띠기초의 휨-비틀림 자유진동)

  • Lee, Byoung Koo;Park, Kwang Kyou;Kang, Hee Jong;Yoon, Hee Min
    • Journal of Korean Society of Steel Construction
    • /
    • v.19 no.5
    • /
    • pp.539-548
    • /
    • 2007
  • This paper deals with flexural-torsional free vibrations of the circular strip foundation with the variable breadth on Pasternak soil. The cross-section of the strip foundation is chosen as the rectangular one with the constant thickness and variable breadth, which is symmetrical about the mid-arc. Also, the foundation that supports the circular strip is modeled as the Pasternak soil with the shear layer. Ordinary differential equations accompanying the boundary conditions are derived. In the governing equations, the transverse, rotatory and torsional inertias are included. These equations are solved numerically and four lowest frequencies are obtained. In the numerical results, the effects of foundation parameters on frequencies are extensively investigated. It is expected that the theories and numerical results of this study can be used in the dynamic design of strip foundations.

Effect of Action Observation Training with Auditory Feedback for Gait Function of Stroke Patients with Hemiparesis

  • Kim, Hyeong Min;Son, Sung Min
    • The Journal of Korean Physical Therapy
    • /
    • v.29 no.5
    • /
    • pp.246-254
    • /
    • 2017
  • Purpose: Previous studies have reported that action observation training has beneficial effects on enhancing the motor task, such as balance and gait functions. On the other hand, there have been few studies combined with action observation training and auditory feedback. The purpose of this study was to determine the effects of action observation training with auditory feedback on the gait function in stroke patients with hemiparesis Methods: A total of 24 inpatients with post-stroke hemiparesis were assigned randomly to either an experimental group 1 (EG 1, n=8), experiment group 2 (EG 2, n=8), control group (CG, n=8, EG 1). The EG 2 and CG watched video clip demonstrating three functional walking tasks with auditory feedback, without auditory feedback, and showing a landscape image, respectively. The exercise program consisted of 30 minutes, five times a week, for four weeks. The participants were measured to 10MWT (10 m walk test), 6MWT (6 minutes walking distance test), TUG (timed up and go test), DGI (dynamic gait index), time and steps of F8WT (figure-of-8 walk test). Results: In the intra-group comparison after the intervention, EG 1 and EG 2 showed a significantly different gait function (10MWT, 6MWT, DGI, TUG, F8WT) (p<0.05). In the inter-group comparison after intervention, EG 1 showed significant improvements in the entire gait parameters and EG 2 only showed significant improvement in DGI and TUG compared to CG (p<0.05). Conclusion: These findings show that action observation training with auditory feedback may be used beneficially for improving the gait function of stroke patients with hemiparesis.

Development of Stochastic Real-Time Forecast System by Storage Function Method (저류함수법을 이용한 추계학적 실시간 홍수예측모형 개발)

  • Bae, Deok-Hyo
    • Journal of Korea Water Resources Association
    • /
    • v.30 no.5
    • /
    • pp.449-457
    • /
    • 1997
  • This study attempts to develop a stochastic-dynamic real-time flow forecasting model for an event-orient watershed storage function model (SFM), which has been used as an official flood computation model in Korea, and to evaluate its performance for real-time flow forecast. The study area is the 747.5$\textrm{km}^2$ Hwecheon basin with outlet at Gaejin and the 8 single flow events during 1983-1986 are selected for comparison and verification of model parameter and model performance. The used model parameters in this study are the same values on field work. It is shown that results from the existing model highly depend on the events, but those from the developed model are stable and well predict the flows for the selected flood events. The coefficient of model efficiency between observed and predicted flows for the events was above 0.90. It is concluded that the developed model that can consider model and observation uncertainties during a flood event is feasible and produces reliable real-time flow forecasts on the area.

  • PDF