| Compared with traditional power generation technology,dish-type concentrating solar photovoltaic power generation technology has attracted much attention due to its concentrating efficiency,high thermal power generation efficiency and low cost,which is expected to become a dominant concentrating power generation technology in the future.Although the current concentrating photovoltaic power generation technology has exceeded 44.7% of power generation efficiency,it still has a large room for improvement.Therefore,in this paper,the research is carried out from three aspects,including the first concentrating unit,the secondary reflector and the tracking control unit in the dish-type concentrating photovoltaic power generation system.Meanwhile,the tracking control strategy,concentrating characteristics and power generation performance are studied in detail as well.After the design of the dish-type concentrating photovoltaic power generation experimental station,verification experiment is carried out,which effectively solved the key problems of tracking control precision,heat dissipation and spot uniformity in the dish concentrating photovoltaic power generation process.The results in this study can provide beneficial option for the commercial application of the high-efficiency photovoltaic power generation technology.Specifically,the main research of this paper is divided into the following aspects.Design of the concentrating unit and secondary reflector.Through simulating with optic software zemax,the segmentation block design idea is adopt and eight sub-mirrors is used to form an entire disk surface to achieve an high solar concentration(up to 570X)and simple manufacturation of concentrating unit.At the same time,the light-receiving characteristics of the secondary reflector were simulated.For the concentrating spot,the homogenizing effect was simulated by the TracePro software for the secondary reflector of different shapes.The results show that the vertical structure of the side wall with high-reflecting mirror and the bottom surface of the cell can guarantee the uniformity of the concentrating spot.Tracking system design: Design a high-precision dish-type concentrating tracking controller based on PLC-1200 as the main controller.A double-axis structure which consisting of a rotary gear motor and an electric push rod and a photoelectric sensor are installed to achieve dual axis tracking.A hybrid control program that implements time control and photoelectric control can ensure automatic switching in both cases of sufficient and insufficient lighting,and automatic operation all day.A computer software in PC is wrote based on QT platform to realize remote monitoring,data collection,data display,power generation detection,threshold alarm and so on.Tracking accuracy measurement and overall performance evaluation: By tracking the temperature of the outer wall of the secondary reflector and the radiation data,the stability of the track control system can be verified.Meanwhile,through comparing the theoretical power generation with the measured power generation,the tracking accuracy is demonstrated to less than 1%.The overall energy efficiency of the photovoltaic thermal system is evaluated and the testing process of the power generation stability and efficiency is discussed in depth.The results show that the optimized concentrating photovoltaic photovoltaic/thermal system has an integrated energy utilization efficiency of 70%.The results of this paper will provide an alternative way for the comprehensive utilization of solar energy.At the same time,it will guide the research of the future dish-type concentrating solar photovoltaic power generation system. |
PDF Full Text Request