Analysis on potential tapping and reconstruction o

2022-08-02
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Analysis on the potential tapping and transformation of small hydropower stations in Yunnan Province Abstract: the potential tapping and technological transformation of small hydropower stations based on unit capacity expansion and transformation is in line with the actual situation of Yunnan Province and the national policy, which can bring obvious economic benefits to small hydropower stations and is an effective method with low investment and quick results. Therefore, it can be said that tapping the potential of hydropower stations is one of the best ways to consolidate and develop the achievements of rural electrification construction in our province

key words: Untitled Document on economic benefits of technological transformation of hydropower stations Yunnan Province is a large hydropower Province in China, with rich hydropower resources. The exploitable capacity is more than 90 million KW, accounting for about 1/5 of the exploitable capacity in China, ranking the second in China. Among them, the exploitable capacity of medium and small hydropower resources is 17.16 million KW; 118 of the 128 counties (cities) in the province can develop and construct small and medium-sized hydropower stations with more than 10000 kW. At the same time, Yunnan is a frontier, mountainous, alpine, barren, multi-ethnic and low productivity province. How to combine the current situation and the local actual situation, transform the advantage of hydropower resources into economic advantage as soon as possible in the near future, and further improve the people's material and cultural living standards is an important topic and primary task for the development of rural hydropower and electrification in our province during the Tenth Five Year plan. Current situation of rural hydropower and electrification in Yunnan Province since the founding of new China, hydropower construction in Yunnan Province has achieved rapid development. By the end of 2000, the local power installed capacity of our province was 2.83 million kW (accounting for 37% of the province's 7.68 million KW). Of the 128 counties (cities) in the province, 99 counties and cities were powered by local small hydropower, and 76 counties and cities and one state (Dehong Prefecture) realized the primary electrification of rural hydropower. From the current situation of local hydropower stations, there are many problems, such as low technical content of equipment, backward production, extensive enterprise management and low quality of personnel. Especially in some old power stations, the problem is more prominent, which has seriously affected the normal production. From the perspective of national policies, the use of high technology to transform traditional industries has become the main outlet for the continued development of the industry. Therefore, it is the most scientific and economic method to consolidate and develop the achievements of rural electrification construction in our province, and it is an effective way for local power to develop and expand itself, by using high and new technologies to carry out technological transformation of the vast rural small hydropower stations in our province, and to tap its own potential, so as to improve the production, operation, management level and economic benefits of the power stations. 2. Main technologies and methods for unit capacity expansion and transformation the object of hydropower station potential tapping and transformation refers to the power station with energy potential, which generally has three situations: first, it has flow potential (the original design of the power station is conservative, and the flow is not fully utilized); Second, it has water head potential (water head is not fully utilized); Third, the variation of actual parameters and design parameters of the power station operation cannot reach the rated output. The potential tapping transformation of the unit mainly involves the flow passage parts of the turbine (runner, water diversion mechanism, spiral case, draft tube) and the generator. The transformation of the generator is relatively simple. Since the generator usually has a capacity margin of about 10%, it is necessary to pay close attention to the temperature change of the generator during the capacity increase. If the temperature of the generator rises a lot, the generator shall be considered for capacity increase and transformation. The method is to update the stator coil, insulation or rotor coil of the generator and improve the insulation grade. The practice shows that when the capacity is increased by about 10%, the generator generally does not need to be transformed. At present, the transformation of the hydraulic turbine mainly adopts the method of replacing a new runner without changing the size of the water guide mechanism, volute, draft tube and the matching size of the runner, so as to achieve the purpose of capacity increase. Therefore, the capacity increase of the turbine is mainly for the runner. At present, the runner in the operation of hydropower stations is mostly designed by the traditional one-dimensional flow theory or two-dimensional potential flow theory. With the development of hydrodynamics and calculation theory, great progress has been made in runner design. A series of more advanced design methods and theories have been developed, including a two-dimensional design model based on S2 flow surface, a quasi three-dimensional design model based on S1 flow surface, a full three-dimensional design model and an optimization design model, which take into account the combined action of runner and guide vanes with rotating runner incoming flow, finite blade thickness and runner blade force. The runner designed based on these advanced design methods and theories has significantly improved its flow capacity and efficiency, so as to achieve the goal of increasing capacity and improving the utilization rate of water resources in the dry season. In the aspect of runner performance analysis, a complete modern turbine design system has been established in China, which is composed of quasi three-dimensional and full three-dimensional inverse problem models of runner. The system can select different weight factors according to different requirements to control various performance indicators of the runner, and realize the control and prediction of blade performance which plays an important role in the national economy through multi-objective optimization. The experimental results show that the predicted performance index of the system is basically consistent with the real machine experiment. This changes the traditional runner development mode of "theoretical design → model experiment → correction → re experiment", greatly shortens the runner development cycle, reduces the R & D cost, and provides a practical possibility for the single piece and customization of the runner. The advanced design and performance prediction methods mentioned above are adopted in the runner transformation of local small and medium-sized hydropower units, which can easily produce high-performance runner more in line with the actual situation of the power station. Its output, efficiency, cavitation performance and other indicators are obviously better than the runner selected and produced according to the traditional type spectrum. The price of this one-piece, customized high-tech runner is only a little higher than that of the traditional runner, but the benefits it brings are very obvious. The statistics of capacity increase and reconstruction show that the unit capacity of the power station can be increased by 10% ~ 20% by replacing the capacity increase runner with good performance on the premise that the size of the flow passage parts of the hydraulic turbine remains unchanged. 3. Benefit and investment of capacity increase and transformation at present, the unit capacity increase and transformation can be carried out for power stations with energy potential and long operation time, which is a good way to benefit both the country and the people with less investment and quick effect. For example, jingguhe power station in our province has a unit capacity of 6300kw, which can only generate 5800kw. After replacing the high-tech runner, the net output of the unit is more than 500kW, and the annual capacity increase benefit is more than 300000 yuan. All the costs of the unit capacity increase and transformation can be recovered as long as the power is generated in a wet season. Cj20-l-180/(2 × 16) The rated output is 6500kw. With the support of a series of preferential policies, the maximum output is 7013 and the pin shaft is 00kw. The generator has a certain capacity increase potential. According to the actual observation of the power station and the unit operation records for many years, the unit output has not exceeded 7000kw

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