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김용기(Yong-Ki Kim),이태원(Tae-Won Lee),김다희(Dae-Hee Kim),유성호(Seong-Ho Yu),엄재식(Jae-Sik Um),김성범(Seong-Beom Kim) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
Major energy savings can be made by simply enabling pumps to run at variable speeds over 30% in some cases. The heart of the energy saving principle of variable speed pumps is the basic hydrodynamic law that the power consumed by centrifugal pumps varies as the cube of impeller speed. But, heating water circulation pumps installed before year 2000 in the district heating system in Korea were adopted the CVF(Constant Volume Flowrate) control method over 10,000 units according to the data of KDHC. The main goal of this study was to estimate the effect for the VVF(Variable Volume Flowrate) control method of heating water circulation pumps by using the real measuring data(flowrate, differential pressure, etc.) and the performance characteristic curve of a variable speed pump. As the results, it was assumed that the total pumping electric power was saved up to over 43.5% by VVF control method in a apartment complex in Korea.
변속 펌프의 에너지 효율 제어를 통한 HVAC 수배관 시스템의 에너지 절감
김서훈(Kim Seo-Hoon),곽노열(Kwak Ro-Yeul) 대한건축학회 2012 대한건축학회논문집 Vol.28 No.2
This paper presents the optimal control strategies for variable speed control systems in office building HVAC hydronic systems to improve their energy efficiencies. It is necessary to prepare a method for reducing energy through efficient energy management on such equipments. In case of regular building, a problem of wasting energy is caused as there is no control on disutility due to degradation of chiller’s performance by applying a constant water volume control system of a constant speed pump to HVAC hydronic system, pump power is wasted under part load operating condition, and there is no change of flow according to load variation. This study applied two strategies for controling energy efficiency through optimal control and operation of pumps of flow according to load variation by applying variable speed control to circulating pumps of the HVAC hydronic system. The first strategy for energy efficiency control is to reduce energy used in circulation part of the HVAC hydronic system through pump sequence control and operating number control by applying wire-to-water efficiency control of pumps. And the second one is an energy efficiency control strategy which controls speed of pumps which circulates and provide flow responding to the load through pressure different setpoint optimal control by using open signals of flow control valves with factors for operating optimal control of HVAC circulation pump system. The results showed that about 6.7?11.9% of heat source energy and 24.4?44.2% of pump energy could be saved by using these optimal control strategies.
가변적인 PID 이득에 기초한 풍력발전 시스템의 피치제어
고정민(Jung-Min Ko),양수형(Soo-Youg Yang),부창진(Chang-Jin Boo),김호찬(Ho-Chan Kim),허종철(Jong-Chul Huh),이정훈(Junghoon Lee),강민제(Min-Jae Kang) 한국지능시스템학회 2013 한국지능시스템학회논문지 Vol.23 No.1
정격풍속이상에서 발전기의 출력을 일정하게 유지하기 위하여 PID에 기초한 다양한 종류의 방법들이 발표되었다. 그러나 고정된 PID 이득을 이용한 이러한 방법에서는 전 영역에서 동작하리라는 보장이 없다. 이 논문에서는 전 영역에서 동작하는 시스템을 설계하기 위하여 풍속의 강도에 따라 PID 이득이 변하는 방법을 제안하였다. 풍속의 강도에 따라 피치각에 따른 전력의 민감도는 계속 변하는데, PID 이득을 민감도의 함수로 유도하였다. For regulating generator speed above the rated wind, versatile methods have been published based on PID. However, these methods with the fixed PID gains could not guarantee that the controller works well in the whole area. In this paper, variable PID gain method has been suggested to overcome this problem. The sensitivity of power to blade pitch angle changes according to wind speed. The variable PID gain function has been derived from this sensitivity.
기계유압식 무단변속기용 기어트레인에 대한 위험속도 해석
배명호(Myung Ho Bae),배태열(Tae Yeol Bae),최성광(Sung Kwang Choi) 유공압건설기계학회 2017 드라이브·컨트롤 Vol.14 No.4
The power train of hydro-mechanical continuously variable transmission (HMCVT) for 8-ton class forklift includes hydro-static units, hydraulic multi-wet disc brake & clutches and complex helical & planetary gears. The helical & planetary gears are key components of HMCVT`s power train wherein strength problems are the main concerns including gear bending stress, gear compressive stress, and scoring failure. Many failures in power train gears of HMCVT are due to the insufficient gear strength and resonance problems caused by major excitation forces, such as gear transmission error of mating gear fair in the transmission. In this study, wherein excitation frequencies are the gear tooth passing frequencies of the mating gears, a Campbell diagram is used to calculate the power train gears’ critical speeds. Mode shapes and natural frequencies of the power train gears are calculated by CATIA V5. These are used to predict resonance failures by comparing the actual working speed range with the critical speeds due to the gear transmission errors of HMCVT’s power train gears.