Yunnan Province is a major hydropower province in China, with abundant hydropower resources, and its exploitable capacity is more than 90 million kilowatts, accounting for about 1/5 of the national exploitable capacity, ranking second in the country. Among them, the exploitable amount of small and medium-sized hydropower resources is17160,000 kilowatts; Of 128 counties (cities) in the province, 1 18 counties (cities) can develop and construct small and medium-sized hydropower stations with a capacity of 1 10,000 kilowatts or more. At the same time, Yunnan is a frontier, mountainous, cold, barren, multi-ethnic and low-level province. How to combine the current situation with the local actual situation, transform the advantages of hydropower resources into economic advantages as soon as possible in the near future, and further improve 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 period.
1 rural hydropower and electrification in Yunnan province
Since the founding of New China, hydropower construction in our province has achieved rapid development. By the end of 2000, the installed capacity of local electric power in our province was 2.83 million kilowatts (accounting for 37% of the installed capacity of local electric power of 7.68 million kilowatts). Among 128 counties (cities) in the province, 99 counties and cities have realized local small hydropower supply, and 76 counties and cities and 1 state (Dehong Prefecture) have realized primary electrification of rural hydropower.
Judging from the existing situation of hydropower stations in various places, there are widespread 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 policy, transforming traditional industries with high technology has become the main way out for the continued development of this industry. Therefore, it is the most scientific and economical way to consolidate and develop the achievements of rural electrification construction in our province, and it is also an effective way for local electric power to develop and expand by using high technology to carry out technological transformation, tap its own potential and improve the production, operation and management level and economic benefits of power stations.
Main technologies and methods for capacity expansion and transformation of Unit 2
The object of tapping the potential of hydropower station 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 utilization is not sufficient); Second, there is head potential (the head is not fully utilized); Third, the actual parameters and design parameters of power station operation can not reach the rated output.
The transformation of tapping the potential of the unit mainly involves the flow components of the hydraulic turbine (runner, water guide mechanism, volute and draft tube) and the generator.
Among them, the transformation of the generator is relatively simple, because the generator usually has a capacity margin of about 10%. In the process of capacity expansion, we should pay close attention to the change of generator temperature. If the generator temperature rises a lot, the generator capacity expansion should be considered. The method is to update the stator coil, insulation or rotor coil of the generator to improve the insulation grade. Practice shows that when the capacity increases by about 10%, it is generally unnecessary to transform the generator.
At present, the transformation of hydraulic turbines is mostly carried out by replacing the new runner without changing the guide mechanism, volute, draft tube size and runner matching size, so as to achieve the purpose of capacity increase. Therefore, the capacity expansion of hydraulic turbine is mainly aimed at runner.
At present, the traditional one-dimensional flow theory or two-dimensional potential flow theory is mostly used to design the runner in hydropower station operation. With the development of fluid mechanics and calculation theory, great progress has been made in runner design, and a series of advanced design methods and theories have been developed, including two-dimensional design model based on S2 stream surface, quasi-three-dimensional design model based on S 1 stream surface, full-three-dimensional design model and optimization design model. These models take into account the interaction of runner and guide vanes, the finite thickness of blades and the stress of runner blades. According to these advanced design methods and theories, the flow capacity and efficiency of the runner are obviously improved, so as to increase the flow and improve the utilization rate of water resources in the dry season.
In the aspect of runner performance analysis, China has established a complete modern turbine design system, including quasi-three-dimensional and full-three-dimensional inverse problem models of runner. The system can choose different weight factors to control the performance index of the runner according to different requirements, and realize the control and prediction of blade performance through multi-objective optimization. The experiment shows that the performance index predicted by the system is basically consistent with the real machine experiment. This has changed the traditional runner development mode of "theoretical design → model experiment → revision → re-experiment", greatly shortened the runner development cycle, reduced the research and development expenses, and provided practical possibilities for the runner to be single and customized.
Local small and medium-sized hydropower units adopt the above-mentioned advanced design and performance prediction methods in runner reconstruction, and according to the actual situation of the power station, it is easy to produce high-performance runners that are more in line with the actual situation of their own 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 integrated customized high-tech runner is only slightly higher than that of the traditional runner, but its benefits are very obvious.
The statistics of capacity-increasing transformation show that the capacity of power station units can be increased by 10% ~ 20% by replacing the capacity-increasing runner with excellent performance on the premise of keeping the size of the flow parts of the turbine unchanged.
3 Benefits and required investment of capacity expansion and transformation
At present, all power stations with energy potential and long operation time can be upgraded, which is a good way with less investment and quick results, benefiting the country and the people.
For example, the Jingguhe Power Station in our province has a single machine capacity of 6300kW, which can only be delivered to 5,800 kW. 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 300,000 yuan. As long as the power is sent in rainy season, all the costs of capacity expansion and transformation of the unit can be fully recovered.
The turbine model of Shuishiban Hydropower Station in Yuanjiang County is CJ20-L- 180/(2× 16), with a rated output of 6500kW and a maximum output of 7000kW. The generator still has a certain expansion potential. According to the actual observation of the power station and the operation records of the unit for many years, the output of the unit does not exceed 7000kW. After replacing CJ925- 180 runner with excellent performance and high efficiency, the output can reach more than 7500kW, which is a precedent for the capacity expansion and transformation of impulse turbine.
By the end of 2000, there were 2,090 local power stations and 3,472 local power stations in our province, with a total capacity of 2.83 million kilowatts, of which nearly 30% were put into operation before the end of 1985, some of which have been in operation for more than 30 years, and the average utilization hours of equipment are less than 2,000 hours. According to the calculation of 20% capacity, 30% installed capacity is transformed, and the installed capacity is increased by 6.5438+0.7 million kW. According to the investment of 7,000 yuan per kilowatt of newly-built power station, it needs about 654.38+0.2 billion yuan. On the premise that the size of the flow parts of the hydraulic turbine remains unchanged, it only takes about 500 yuan to replace the capacity-increasing runner with excellent performance, and it only takes 85 million yuan to increase the capacity of 65.438+700,000 kilowatts. In the current situation of shortage of funds for hydropower construction, this has obvious advantages over developing new power points. Moreover, in principle, power stations without regulating performance will not be listed and will not be built again.
Of course, from the analysis of the possibility of tapping the potential, the power stations that need to be rebuilt are all power stations with early construction, good hydraulic conditions, simple development and poor equipment. However, there must be a scientific and reasonable plan to tap the potential of transformation. At present, it is urgent to make a general survey of local small and medium-sized hydropower stations in the province, classify the power stations that need to be transformed, and formulate scientific and feasible transformation schemes according to the conditions of capital, technology and benefit, combined with local economic development and network layout. Priority is given to renovation projects with low cost and good benefits. For a specific power station, we must first find out the problems, and then the transformation content (hydraulic, mechanical, electrical, etc.). ) should be determined, and the feasibility (technology, economy, safety, etc. ) and the transformation plan should be carefully analyzed to prevent blind transformation and transformation without changing the effect.
4. Raising funds for technological innovation
Premier Zhu Rongji pointed out during his recent inspection tour in Hunan that "small hydropower should be vigorously developed and supported". The Tenth Five-Year Plan for Water Conservancy has determined a series of preferential policies for building 400 hydropower rural electrification counties in China. Our province will organically combine with power station potential tapping and technical transformation to create favorable conditions for capacity expansion and transformation of units.
At present, our bureau attaches great importance to technical transformation, and will give some help and guidance to some projects with good benefits and difficult funds for transformation. Funds can be raised through multiple channels: ① "using electricity to support electricity" funds and depreciation funds of power stations; ② Raise funds through reorganization; (3) you can apply to the relevant departments for special subsidies for technological transformation; (4) loans to the financial sector, etc.
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