After the construction of Qinghai-Tibet Highway and Railway, the Qinghai-Tibet Power Transmission(QTPT) line is another major permafrost engineering project with new types of engineering structures. The changing proce...After the construction of Qinghai-Tibet Highway and Railway, the Qinghai-Tibet Power Transmission(QTPT) line is another major permafrost engineering project with new types of engineering structures. The changing process and trend of ground temperature around tower foundations are crucial for the stability of QTPT. We analyzed the change characteristics and tendencies of the ground temperature based on field monitoring data from 2010 to 2014. The results reveal that soil around the tower foundations froze and connected with the artificial permafrost induced during the construction of footings after the first freezing period, and the soil below the original permafrost table kept freezing in subsequent thawing periods. The ground temperature lowered to that of natural fields, fast or slowly for tower foundations with thermosyphons,while for tower foundations without thermosyphons, the increase in ground temperature resulted in higher temperature than that of natural fields. Also, the permafrost temperature and ice content are significant factors that influence the ground temperature around tower foundations. Specifically, the ground temperature around tower foundations in warm and ice-rich permafrost regions decreased slowly, while that in cold and ice poor permafrost regions cooled faster. Moreover, foundations types impacted the ground temperature, which consisted of different technical processes during construction and variant of tower footing structures. The revealed changing process and trend of the ground temperature is beneficial for evaluating the thermal regime evolution around tower foundations in the context of climate change.展开更多
Concentrating solar thermal power system can provide low carbon,renewable energy resources in countries or regions with strong solar irradiation.For this kind of power plant which is likely to be located in the arid a...Concentrating solar thermal power system can provide low carbon,renewable energy resources in countries or regions with strong solar irradiation.For this kind of power plant which is likely to be located in the arid area,natural draft dry cooling tower is a promising choice.To develop the experimental studies on small cooling tower,a 20 m high natural draft dry cooling tower with fully instrumented measurement system was established by the Queensland Geothermal Energy Centre of Excellence.The performance of this cooling tower was measured with the constant heat input of 600 kW and 840 kW and with ambient temperature ranging from 20 ℃ to 32 ℃.The cooling tower numerical model was refined and validated with the experimental data.The model of 1 MW concentrating solar thermal supercritical CO2 power cycle was developed and integrated with the cooling tower model.The influences of changing ambient temperature and the performance of the cooling tower on efficiency of the power system were simulated.The differences of the mechanism of the ambient temperature effect on Rankine cycle and supercritical CO2 Brayton cycle were analysed and discussed.展开更多
A review is conducted about the application of the evaporative cooling technology in thermal power plants.Different case studies are considered,namely,evaporative air conditioners,evaporative cooling in direct air-coo...A review is conducted about the application of the evaporative cooling technology in thermal power plants.Different case studies are considered,namely,evaporative air conditioners,evaporative cooling in direct air-cooled systems,gas turbine inlet cooling,wet cooling towers,and hybrid cooling towers with a crosswind effect.Some effort is provided to describe the advantages related to direct evaporative cooling when it is applied in thermal power plants and illustrate the research gaps,which have not been filled yet.In particular,typical case studies are intentionally used to compare the cooling performances when direct evaporative cooling is implemented in different types of cooling towers,including the natural draft wet cooling tower(NDWCT)and the pre-cooled natural draft dry cooling tower(NDDCT).It is shown that the NDWCT provides the best cooling performance in terms of power station cooling,followed by the pre-cooled NDDCT,and the NDDCT;moreover,the evaporative pre-cooling is able to enhance the cooling performance of NDDCT.Besides,on a yearly basis,better NDDCT cooling performances can be obtained by means of a spray-based pre-cooling approach with respect to wet media pre-cooling.Therefore,the use of nozzle spray is suggested for improvement in the performance of indirect/direct air-cooling systems with controlled water consumption.展开更多
In order to improve the reliability of fault identification of the double-circuit transmission lines on the same tower, a new algorithm for fast protection of double-circuit transmission lines on the same tower based ...In order to improve the reliability of fault identification of the double-circuit transmission lines on the same tower, a new algorithm for fast protection of double-circuit transmission lines on the same tower based on the reactive powers of traveling wave is proposed. With the implementation of S-transform, the initial traveling wave reactive powers are calculated and the change characteristics of reactive power under different fault conditions are studied. The protection criterion is constructed by analyzing the ratio of the reactive powers of the same end on double-circuit transmission lines and the ratio of the reactive powers at both ends on the same line. According to the ratio of reactive power on the same side of the line and both ends of the same line, it is possible to identify whether the faults of the double-circuit line of the same tower occurred in or out of the protection zone. A large number of simulation results show that the protection performance is sensitive and reliable, and quick to respond. The criterion is simple and is basically not affected by fault initial angles, fault types, and transitional resistances.展开更多
基金supported by National Natural Science Fund of China (Grant No. 41401088)State Grid Qinghai Electric Power Research Institute (SGQHDKYOSBJS201600077, SGQHDKYOSBJS 1700068)Funds of State Key Laboratory of Frozen Soil Engineering (Nos. SKLFSE-ZY-17, SKLFSEZT-32)
文摘After the construction of Qinghai-Tibet Highway and Railway, the Qinghai-Tibet Power Transmission(QTPT) line is another major permafrost engineering project with new types of engineering structures. The changing process and trend of ground temperature around tower foundations are crucial for the stability of QTPT. We analyzed the change characteristics and tendencies of the ground temperature based on field monitoring data from 2010 to 2014. The results reveal that soil around the tower foundations froze and connected with the artificial permafrost induced during the construction of footings after the first freezing period, and the soil below the original permafrost table kept freezing in subsequent thawing periods. The ground temperature lowered to that of natural fields, fast or slowly for tower foundations with thermosyphons,while for tower foundations without thermosyphons, the increase in ground temperature resulted in higher temperature than that of natural fields. Also, the permafrost temperature and ice content are significant factors that influence the ground temperature around tower foundations. Specifically, the ground temperature around tower foundations in warm and ice-rich permafrost regions decreased slowly, while that in cold and ice poor permafrost regions cooled faster. Moreover, foundations types impacted the ground temperature, which consisted of different technical processes during construction and variant of tower footing structures. The revealed changing process and trend of the ground temperature is beneficial for evaluating the thermal regime evolution around tower foundations in the context of climate change.
文摘Concentrating solar thermal power system can provide low carbon,renewable energy resources in countries or regions with strong solar irradiation.For this kind of power plant which is likely to be located in the arid area,natural draft dry cooling tower is a promising choice.To develop the experimental studies on small cooling tower,a 20 m high natural draft dry cooling tower with fully instrumented measurement system was established by the Queensland Geothermal Energy Centre of Excellence.The performance of this cooling tower was measured with the constant heat input of 600 kW and 840 kW and with ambient temperature ranging from 20 ℃ to 32 ℃.The cooling tower numerical model was refined and validated with the experimental data.The model of 1 MW concentrating solar thermal supercritical CO2 power cycle was developed and integrated with the cooling tower model.The influences of changing ambient temperature and the performance of the cooling tower on efficiency of the power system were simulated.The differences of the mechanism of the ambient temperature effect on Rankine cycle and supercritical CO2 Brayton cycle were analysed and discussed.
基金supported by the Shandong Natural Science Foundation(Grant No.ZR2022ME008)the Shandong Provincial Science and Technology SMEs Innovation Capacity Improvement Project(2022TSGC2018)+3 种基金the Shenzhen Science and Technology Program(KCXFZ20201221173409026)The financial supports from the“Young Scholars Program of Shandong University”(YSPSDU,No.2018WLJH73)the Open Project of State Key Laboratory of Clean Energy Utilization,Zhejiang University(Program Number ZJUCEU2020011)the Shandong Natural Science Foundation(Grant No.ZR2021ME118)are gratefully acknowledged。
文摘A review is conducted about the application of the evaporative cooling technology in thermal power plants.Different case studies are considered,namely,evaporative air conditioners,evaporative cooling in direct air-cooled systems,gas turbine inlet cooling,wet cooling towers,and hybrid cooling towers with a crosswind effect.Some effort is provided to describe the advantages related to direct evaporative cooling when it is applied in thermal power plants and illustrate the research gaps,which have not been filled yet.In particular,typical case studies are intentionally used to compare the cooling performances when direct evaporative cooling is implemented in different types of cooling towers,including the natural draft wet cooling tower(NDWCT)and the pre-cooled natural draft dry cooling tower(NDDCT).It is shown that the NDWCT provides the best cooling performance in terms of power station cooling,followed by the pre-cooled NDDCT,and the NDDCT;moreover,the evaporative pre-cooling is able to enhance the cooling performance of NDDCT.Besides,on a yearly basis,better NDDCT cooling performances can be obtained by means of a spray-based pre-cooling approach with respect to wet media pre-cooling.Therefore,the use of nozzle spray is suggested for improvement in the performance of indirect/direct air-cooling systems with controlled water consumption.
文摘In order to improve the reliability of fault identification of the double-circuit transmission lines on the same tower, a new algorithm for fast protection of double-circuit transmission lines on the same tower based on the reactive powers of traveling wave is proposed. With the implementation of S-transform, the initial traveling wave reactive powers are calculated and the change characteristics of reactive power under different fault conditions are studied. The protection criterion is constructed by analyzing the ratio of the reactive powers of the same end on double-circuit transmission lines and the ratio of the reactive powers at both ends on the same line. According to the ratio of reactive power on the same side of the line and both ends of the same line, it is possible to identify whether the faults of the double-circuit line of the same tower occurred in or out of the protection zone. A large number of simulation results show that the protection performance is sensitive and reliable, and quick to respond. The criterion is simple and is basically not affected by fault initial angles, fault types, and transitional resistances.
