Some views on improving the annual power generation of small hydropower stations

There are only three small rivers in Bishan County, namely Binan River, Bibei River and Meijiang River, which do not cross the river. The total amount of water resources in Bishan County is about 337,865,438+0,000m3, and the average runoff depth for many years is 340mm, 350mm and 360mm respectively, so water resources are very scarce. The construction of small hydropower stations in Bishan County started in September. 1979. Up to now, seven small hydropower stations have been built, namely Dashuitang, Zhoujiadong, Baihe, Shawan, Shuangjiankou, Tiaodeng and Gaodong. The total installed capacity of the county is only 1280 kW. 17 July 2~4m, Bishan County suffered a once-in-a-century disaster. In the whole year, * * * generated 4.04 million kWh of electricity, with an annual utilization of 3 156h, and realized a profit of 1.83 million yuan, which achieved good economic benefits. In recent years, we have discussed and practiced how to improve the annual power generation of small hydropower stations, and achieved good results.

First, pay attention to maintenance work

After years of operation, it shows that the maintenance quality of small hydropower stations greatly affects the annual power generation of power stations. To this end, every small hydropower station in Bishan County has set up a maintenance team, and arranges time to do the following main work in the dry season every year: First, organize personnel to overhaul the water machine, check and maintain the generator, and ensure the normal operation of the unit; The second is to maintain the control panel, transformers, lines, etc. At the same time, test the lightning arrester and the grounding resistance of the power station to ensure that there are few or no accidents during the main power generation period (rainy season); The third is to remove the rocks, silt and other debris in the diversion channel, forebay, turbine room and tailrace, and plug the loopholes in the barrage, diversion channel and forebay. The county water affairs bureau dispatched professional technicians to the maintenance site in time to help the power station do a good job of maintenance, which not only ensured the safe operation of the power station, but also improved the power generation output of the unit and generated more power.

Second, reduce cavitation of water machine.

Cavitation is a common phenomenon in small hydropower stations, which causes unit vibration, reduced efficiency and reduced output, which not only shortens the maintenance cycle and increases the maintenance workload, but also affects the output of the power station and reduces the power generation. Through analysis, there are four main reasons for cavitation of turbine in Bishan small hydropower station: first, the runner quality of some hydropower stations is unqualified, and the blade surface is not smooth, which changes the flow streamline and provides favorable conditions for cavitation; Second, the vibration of the unit is serious, which intensifies cavitation; Third, the long-term low-load operation makes the water machine often run in the inefficient area, producing a large number of bubbles; Fourth, the maintenance is not timely, leading to more and more cavitation. In view of these problems, we have taken corresponding measures.

1 Adjust operating conditions

When the unit is running, the head and output range are determined according to the operation characteristic curve of the power plant turbine to ensure that the unit is in operation. Under normal circumstances, the load is not less than 30 ~ 40% of the rated output.

2 Minimize vibration.

In the operation of small hydropower stations, unit vibration is a common fault, which not only aggravates the cavitation of the turbine, but also destroys the stable operation of the unit, loses energy and reduces the economic benefits of the power station. The vibration of units in Tiaodeng, Zhoujiadong, Baihe, Shawan and Shuangjiankou hydropower stations in Bishan County is serious. We analyzed the vibration causes of each station, treated them separately, reduced the vibration and achieved good results.

3. Strengthen maintenance

Each power station has formulated relevant inspection and maintenance systems, and gradually formed a scientific, institutionalized and regular system, and timely repaired the cavitation runner by welding and replaced the runner with unqualified quality. For example, after the runner of Shawan Power Station (2× 100kW) in Guangpu Town is replaced, the output of 1 unit is 15kW, and that of unit 2 is 18kW, which can increase the income by more than 25,000 yuan per year.

Third, salvage sundries in time.

Every flood season, there will be a lot of sundries (mostly weeds, water hyacinths and leaves) in the three small rivers in Bishan County, and sometimes they will gather together like hills and rush to the water intake of the power station. On the one hand, it poses a threat to the safety of the power station, on the other hand, it reduces the quoted flow and power generation head of the power station. In order to remove sundries and improve power generation output, each station has formulated relevant systems, and regularly patrol to check whether the trash rack is blocked by sundries and remove it in time.

According to the recorded data of the power station over the years, the output and annual power generation of the unit after the trash rack is removed are analyzed and calculated.

Fourth, strengthen water resources management.

The small hydropower station in Bishan County has a certain storage capacity. After years of observation, analysis and summary, we have rich experience in the law of annual water inflow. In operation, we strive to achieve the following points according to the abundant and dry conditions:

1 rainy season

All stations should listen to and watch radio and TV weather forecast programs, observe the incoming water situation at any time, empty the water storage as much as possible before the big flood, reduce water abandonment and generate more electricity.

2 dry season

The output of small hydropower stations mainly depends on the working head and the flow through the turbine. For low-head hydropower stations (the working heads of small hydropower stations in our county are all between 4.5 ~ 16m), the power generation increases obviously. In the dry season, "high head" power generation can be realized without running water upstream. Especially for Zhoujiadong, Baihe, Shawan, Shuangjiankou and Tiaodeng power stations developed by Binan River cascade, it is necessary to scientifically arrange the power generation time of each power station in dry season to ensure that the upstream and downstream power stations do not abandon water or less.

Verb (abbreviation of verb) conversion of grid-connected lines

In recent years, due to the shortage of power supply, power outages in large power grids are very frequent, which not only brings inconvenience to users, but also brings great economic losses to power stations (because only power is generated without power supply, when the power grid fails, the power stations cannot be sent out). In order to reverse this situation, some qualified power stations have simply reformed the grid-connected lines. When the power grid fails, the power station operates in isolation and supplies power to some users, which increases the income of the power station and is well received by users. According to statistics, the average annual power generation of Dashuitang, Zhoujiadong, Baihe, Shawan, Gaodong and Tiaodeng power stations in our county is about 497,700 kWh, accounting for about 10% of the county's annual power generation.