• Title, Summary, Keyword: Variable speed

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The Analysis of Life Cycle Cost and Cooling Water Circulating Pump Energy Saving According to Variable Speed Pressure Differential Setpoint Control Strategy

  • Kim, Seo-Hoon;Kim, Jong-Hun;Jang, Cheol-Yong;Song, Kyoo-dong
    • KIEAE Journal
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    • v.15 no.4
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    • pp.37-43
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    • 2015
  • Purpose : The study applied control strategy to reduce through optimal control and operation of pump by applying control on variable speed to the circulation pump of HVAC system in the office building. The study has the purpose to review validity of control on variable speed as ESMs(Energy Saving Measures) and establish the control technology on variable speed pump. The study performed reduction analysis of building energy and economic evaluation of pump through energy effectiveness control strategy of HVAC system. Method: The study sought possible reduction through energy control strategy which can provide proper flow fitting to building load by applying control on variable speed pump. The study applied control strategy to reduce through pressure differential set-point control and operation of pump by applying control on variable speed to the circulation pump of HVAC system in the office building. Result : The results showed that about 16-35% of pump energy could be saved by using these optimal control strategies. In the result of analysis on 10 years life cycle cost of analysis on payback period of initial investment pump, variable speed pump control showed 5.1 years.

Study on Vibration Characteristics after Applying Variable Speed Control to Constant Speed Fans used in a Power Plant (발전소 통풍계통의 가변속 적용 후 진동특성에 관한 연구)

  • Cho, C.W.;Song, O.S.;Yang, K.H.;Kim, G.Y.;Cho, S.T.;Moon, H.D.
    • Journal of the Korea Society For Power System Engineering
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    • v.13 no.6
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    • pp.88-94
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    • 2009
  • In this paper, vibration characteristics after applying variable speed control to fans with a rated speed used in a power plant are studied by performing experiments and analyzing finite element models. Then the campbell diagram is presented to verify the reason of the abnormal vibration measured from fan structure during variable operation of Forced Draft Fan & Induced Draft Fan. According to results, it is found that amplitude of acceleration increases abruptly when a 2X harmonic component meets the natural frequency of fan rotor. Therefore it is very important thing that investigate exactly dynamic characteristics for the rotor at variable speed zone before applying variable speed control to a rotor with a rated speed.

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A design of vertical axis wind power generating system combined with Darrieus-Savonius for adaptation of variable wind speed (다변풍속 적응형 Darrieus-Sauonius 초합 수직푹 풍력발전 시스템의 설계)

  • 서영택;오철수
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.45 no.2
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    • pp.185-192
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    • 1996
  • This paper presents a design of vertical axis Darrieus wind turbine combine with Savonius for wind-power generating system to be adapted for variable wind speed. The wind turbine consists of two troposkien- and four Savonius-blades. Darrieus turbine is designed with diameter 9.4[m], chord length 380[mm], tip speed ratio 5. Savonius turbine is designed with diameter 1.8[m], height 2[m], tip speed ratio 0.95. The design of turbine is laid for the main data of rated wind speed 10[m/s], turbine speed 101.4[rpm]. The generating power is estimated to maximum power 20[kW], and this is converted to commercial power line by means of three phase synchronous generator-inverter system. Generating system is designed for operation on VSVF(variable speed variable frequency) condition and constant voltage system.

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High Performance MPPT Based on Variable Speed Generator Driven by Wind Power Generation in Battery Applications

  • Padmanabhan, Sutha;Kaliyappan, Kannan
    • Journal of Electrical Engineering and Technology
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    • v.9 no.1
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    • pp.205-213
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    • 2014
  • A wind generator (WG) maximum power point tracking (MPPT) system is presented here. It comprises of a variable-speed wind generator, a high-efficiency boost-type dc/dc converter and a control unit. The advantages of the aimed system are that it does not call for the knowledge of the wind speed or the optimal power characteristics and that it operates at a variable speed, thus providing high efficiency. The WG operates at variable speed and thus suffers lower stress on the shafts and gears compared to constant-speed systems. It results in a better exploitation of the available wind energy, especially in the low wind-speed range of 2.5-4.5 m/s. It does not depend on the WG wind and rotor-speed ratings or the dc/dc converter power rating. Higher reliability, lower complexity and cost, and less mechanical stress of the WG. It can be applied to battery-charging applications.

Speed Control of the Motor in Automatic Control Using the Thyristor (싸이리스터에 의한 전동기 속도의 자동제어에 관한 연구)

  • Min Ho Park
    • 전기의세계
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    • v.19 no.2
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    • pp.6-11
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    • 1970
  • For the variable speed in automatic control, this paper describes, at first, performance equations of an induction motor which has the free rotating stator. This motor with rotating stator has a speed control factor itself by equivalent variable frequency in stator side. Secondly, an additional invertor source on the rotor slip ring serves the purpose of improving the speed control factor. The advantages decribed above permit to control the speed continuosly from zero to maximum allowable speed with low energy of thyristor a feed-back device may be used for speed stabilization under variable load.

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Voltage Impacts of a Variable Speed Wind Turbine on Distribution Networks

  • Kim, Seul-Ki;Kim, Eung-Sang
    • KIEE International Transactions on Power Engineering
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    • v.3A no.4
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    • pp.206-213
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    • 2003
  • The main purpose of this paper is to present a simulation model for assessing the impacts of a variable speed wind turbine (VSWT) on the distribution network and perform a simulation analysis of voltage profiles along the wind turbine installed feeder using the presented model. The modeled wind energy conversion system consists of a fixed pitch wind turbine, a synchronous generator, a rectifier and a voltage source inverter (VSI). Detailed study on the voltage impacts of a variable speed wind turbine is conducted in terms of steady state and dynamic behaviors. Various capacities and different modes of variable speed wind turbines are simulated and investigated. Case studies demonstrate how feeder voltages are influenced by capacity and control modes of wind turbines and changes in wind speed under different network conditions. Modeling and simulation analysis is based on PSCAD/EMTDC a software package.

Modeling of a Variable Speed Wind Turbine in Dynamic Analysis

  • Kim, Seul-Ki;Kim, Eung-Sang;Jeon, Jin-Hong
    • KIEE International Transactions on Power Engineering
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    • v.4A no.2
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    • pp.51-57
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    • 2004
  • This paper describes the dynamic performance of a variable speed wind turbine system responding to a wide variety of wind variations. Modeling of the wind generation using power electronics interface is proposed for dynamic simulation analysis. Component models and equations are addressed and their incorporations into a transient analysis program, PSCAD/EMTDC are provided. A wind model of four components is described, which enables observing dynamic behaviors of the wind turbine resulting from wind variations. Controllable power inverter strategies are intended for capturing the maximum power under variable speed operation and maintaining reactive power generation at a pre-determined level for constant power factor control or voltage regulation control. The components and control schemes are modeled by user-defined functions. Simulation case studies provide variable speed wind generator dynamic performance for changes in wind speed

A Study on the Performance Evaluation of Variable-speed Drive Pump (가변속펌프의 성능평가방법에 관한 연구)

  • Suh, Sang-Ho;Kim, Hyoung-Ho;Rakibuzzaman, Rakibuzzaman;Kim, Kyung-Wuk;Yoon, In-Sik
    • The KSFM Journal of Fluid Machinery
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    • v.17 no.5
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    • pp.83-88
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    • 2014
  • Pumps are widely used in industrial plants, energy systems, ships etc. Generally they consume nearly 20% each nation's total electrical energy. The objective of this study is to find performance evaluating method for variable-speed drive pump. In order to evaluate the variable-speed pump performance energy saving rate for the variable-speed pump is applied and compared with that of constant-speed pump.

A Study of Control Method of SRM for Variable Speed Control

  • Park, Heesung;Hwang, Yeongseong;Seong, Sejin;Choi, Jaedong
    • Proceedings of the KIPE Conference
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    • pp.754-757
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    • 1998
  • In this paper, the fuzzy control logic of Switched Reluctance Motor(SRM) is introduced to apply the variable speed drive system. Since the speed-torque property of SRM has high speed variation to the changes of torque like a DC motor, to apply SRM to the variable speed driving system, the optimal speed-torque control method is required. As the control method like this, the fuzzy logic and PI control are proposed, and characteristics of them are compared and verified through the experimental results

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On-line Fault Detection and Diagnosis for Heat Exchanger of Variable Speed Refrigeration System Based on Current Information (전류정보를 이용한 가변속냉동시스템의 열교환기 실시간 고장 진단)

  • Lee, Dong-Gyu;Jeong, Seok-Kwon
    • Proceedings of the SAREK Conference
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    • pp.88-94
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    • 2007
  • This study deals with on-line fault detection and diagnosis for heat exchanger of variable speed refrigeration system. Conventional studies about fault of heat exchanger in refrigeration system have used temperature and pressure information. The temperature and pressure are able to be used valuably for faults detection of constant speed refrigeration system. However in case of variable speed refrigeration system, the temperature and pressure are no longer useful information for fault detection due to compensation effect of feedback controller. While current information is possible to detect faults of variable speed refrigeration system. The current information was detected in an inverter, it was used after transforming rms value. The faults of variable speed refrigeration system are divided into electrical faults and mechanical faults. We performed fault detection and diagnosis about heat exchanger among mechanical faults such as condenser fouling and evaporator fan fouling through some experiments.

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