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본 논문은 기존의 추적방식인 아날로그 방식의 하드웨어적 제어에서 탈피하여 디지탈 방식의 소프트웨어적 제어방식인 적응제어 이론을 태양 추적장치에 적용하여 정확하고 간단하게 추적하는 제어장치를 설계 제작하고, 이에 대한 성능을 평가하였다.<br/> 추적회로에 적용할 제어이론은 최근 로보트 제어에 적용하여 각광을 받고있는 Adaptive independent control 이론을 도입하였다. 이 제어이론을 태양 주적장치에 적용했을 경우의 효과에 대해 모델링에 의한 컴퓨터 시뮬레이션을 행하였고, 그 결과, 제어이론을 적용한 경우가 좀더 정확한 추적을 행하며, 추적오차를 약 1/2 정도 줄일 수 있음을 알았다. 추적 제어장치의 제작은 DALLAS 사의 DS5000T를 마이크로 프로세터로 사용하여 회로를 간소화 시켰으며, 제작된 추적장치를 실제로 동작시켜 추적이 제대로 행해지는지를 엔코더와 Data Acquisition System을 설치하여 측정하였다. 측정 결과는 시뮬레이션의 경우와 근접했으며, 적응제어 이론을 적용한 추적 제어장치가 태양을 더 정확하게 추적함을 알 수 있었다. This study aims at developing the control device of solar tracking system which can accurately track the sun with a simple operation. Actual control device is designed and manufactured to evaluate its performance. The digital control method base on recently developed adaptive control theory is adopted for main control algorithm instead of a traditional analog control method.<br/> Adaptive independent control theory is introduced for the control algorithm of tracking circuit, which is prevailing in the field of robot control nowadays. Computer simulation of solar tracking model reveals the new device operated by control theory could reduce the error to one half with the comparison of a existing device. Tracking circuit can be simplified by adopting the DS5000T ?-processor made by the DALLAS company. Actual measurement is conducted to verify the correct operation of manufactured control device with a encorder and a data acquisition system. The experimental results coincided with the simulation results, and our new tracking control device operated by adaptive control theory can track the sun more accuratly.
Concentration errors critically affect the performance of solar concentrator, so their evaluation is important to the concentrated solar power technology. However, the evaluation is very challenging because error sources are various and not easy to measure individually. Therefore, the integrated effect of concentration errors is often more interesting and useful for large-scale applications. In the present work, we analytically investigate and classify various concentration error sources and then explain that the effect of various concentration errors can be represented in terms of a root mean square value of reflector surface slope error. We present an indirect approach to assessing the reflector surface slope error by comparing solar flux measurement data with modeling calculations. We apply the approach for solar furnaces with different thermal capacity and investigate its advantages and disadvantages.
It is important to evaluate concentration errors due to its critical role to the concentrated solar power technology. Nonetheless, the evaluation of concentration errors is challenging because error sources are various and they are not easy to measure and count all together. In this paper, we explain that concentration errors can be represented in terms of a root mean square value of reflection surface slope errors. Then we present an indirect approach to assessing the reflection surface slope errors by comparing solar flux measurement data with modeling calculation. We applied the approach for solar furnaces and investigated its feasibility.
본 연구에서는 태양열온수급탕시스템의 장기성능평가를 위한 실험과 TRANSYS를 이용한 시뮬레이션을 수행하였다. PSTAR 방법을 이용한 성능평가는 기존 열성능평가보다 년성능평가를 가능하게 함을 입증하였다. 입증모델의 다양한 에너지 개념의장기성능평가와 에너지량을 계산하였고, 모델시스템의 Audit Model을 작성하여 재표준화 계수를 산정하였다. There is an absolute need to establish standards for testing and performance rating to develop a high-efficiency solar domestic hot water systems for practical utilization and promotion of solar energy, since most of solar domestic hot water systems marketed presently are imported from foreign countries.<br/> The new standard for testing and performance rating should allow accurate, sound intercomparision of alternative systems.<br/> It also should be a means of opimizing a new or developing system design. The objective of this paper is to analyze thermal performance data and simulation modeling for the rating of SDHWS using TRANSYS.<br/> A new method is introduced, based on PSTAR Method, with reconcilation data and model.<br/> Renomalized terms are calculated to validate the model.
Daegu Solar Power Tower Plant of a 200 kW thermal capacity uses an open air receiver. An air receiver is generally based on the volumetric receiver concept with porous ceramic absorbers. Because absorber material is important in the volumetric receiver, ceramic materials with excellent thermal conductivity, high solar absorptivity and good thermal stability have been researched. KEER also developed SiC honeycomb absorber modules and evaluated performance of the modules at the KIER solar furnace. For performance evaluation, we made an open volumetric receiver containing the modules and measured the outlet temperature and the efficiency. It is demonstrated that performance of the KEER absorber is comparable to that of a reference absorber developed by DLR.
The Dish/Stirling system with the Stirling engine is currently used to convert solar energy directly to electrical energy. Successful operation of dish/Stirling system is supported by hybrid system, which will allow continuous operation driven by solar and combustion heating. The hybrid Receiver has to be provided with an additional combustion system. The heat pipe receiver and conbustion system were manufactured and tested for thermal characteristics of receiver. Maximum temperature difference along the heat pipe surface is 200?C. Emission measurements showed low NOx values of 28 to 46 ppm and very high CO values of 18 to 201 ppm.
The solar simulator system is designed for indoor tests of solar thermal receivers and reactors in the case of changeable weather conditions. Because the solar simulator allows the control of electric power input, it is easy to adjust solar thermal power input and thus to implement accurate tests of receivers. Recently, we have manufactured a solar simulator, which is comprised of three sets of a xenon lamp and an elliptical reflector. In order to serve as a test facility, optical characterization of the solar simulator via radiation heat flux measurement is a critical prerequisite. We used the flux mapping method that the measurement error proved to be less than 5% and individually measured the flux distribution of the three lamps. We presented the measurement results in terms of the heat flux distribution, the maximum heat flux, the power distribution, and the efficiency for electric power conversion into radiation power.
Industry related project for a year to develope commercial model of 10 ㎾ dish-Stirling solar thermal power system by modifying possessed one was taken as the objectives. During this project, commercial solar tracking system, control and monitoring system, high durability reflector, and long term operation were performed. The commercial solar tracking system was tested for 4 months to investigate the degree of precision and adapted from October to the control system for an actual operation. Sun tracking accuracy of 3 mrad using modified control system adapted to the Dish-Stirling system was satisfied during the experimental period. The monitoring system displays temperature of receiver's rear plate, cooling water, oil, and etc., engine pressure, electric generation amounts, and generator RPM and weather data of Direct Normal Irradiation, Horizontal Global Insolation, wind speed & direction, and temperature. During 4 months from September to December, operating results had been stored as a excel file automatically. Experimental results of December 16th was selected and shown as a representative data. When DNI increased higher than 800 W/㎡, the solar-to-electric efficiency reached to about 20%. When DNI became 850 W/㎡, the 7 ㎾ power was generated. The solar to electricity efficiency can be reached to 19% under the DNI of 700 W/㎡ and increased to 20% when the constant DNI is over 900 W/㎡ As a results, the power generation trend as a function of DNI can be expressed a liner curve.