Operation and maintenance of micro hydroelectric power plants. Encyclopedia of radio electronics and electrical engineering

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The operation and maintenance of the micro hydroelectric power station must be carried out in accordance with the instruction manual for the micro hydroelectric power station. In order to constantly monitor the state of the micro hydroelectric power station, as well as water parameters, the owners of the micro hydroelectric power station must keep a log of inspection and observation of the micro hydroelectric power station. This journal contains data from inspections (observations and measurements) of equipment and hydraulic structures of micro hydroelectric power plants, water parameters, both in the river and in hydraulic structures of micro hydroelectric power plants.

The operating instructions can be provided to the owner of a micro HPP, either by the person (or contractor) who built this facility, or developed directly by the owner himself (if the construction of the micro HPP was carried out independently).

The operating manual for a micro HPP should contain the following information:

• list of hydraulic structures, their purpose and operational functions;
• list of equipment, its purpose and operational functions;
• characteristics of the materials of hydraulic structures (type of material from which the structure is made, etc.);
• technical passport and operating instructions for the hydraulic unit (provided by the manufacturer of the hydraulic unit);
• the procedure for operating a micro hydroelectric power station: under normal operating conditions, when floods and high waters are skipped, during a frosty period, in emergency conditions;
• safety requirements for the operation of micro HPPs;
• the procedure for the preparation and repair of hydraulic structures and the hydroelectric unit of a micro hydroelectric power station;
• approximate dates: the beginning and end of the flood; the appearance of sludge; freezing of water in the river;
• flow characteristics of a hydraulic turbine (hydroturbines);
• list and layout of all control and measuring instruments (KIP);
• methodology for performing instrumentation measurements.

Below are general provisions for the operation of micro HPPs, which contain provisions applicable to most micro HPPs of the diversion type. At the same time, these general provisions should be supplemented, depending on the type of micro hydroelectric power station, its capacity and specific hydraulic features.

The procedure for operating a micro hydroelectric power station

1. Start and stop

1.1 At the time of launching the micro HPP, it is necessary to fill the pressure basin with water to the volume that ensures the operation of the hydroelectric unit, as well as the pressure pipeline. At the time of filling with water, these hydraulic structures are not allowed to supply water to the turbine.

1.2. To fill hydraulic structures with water, it is necessary to open the gate (gates) of the water intake structure and ensure the intake of water into the diversion canal. Water intake into the diversion canal is ensured by opening the gate of the intake structure, which provides the necessary filling of the diversion canal and the passage of the required water flow.

1.3. If the diversion canal and/or the penstock contain overflows or a system for discharging excess water, then water can be drawn into such a diversion canal with the intake gates fully raised. However, in this case, it must be remembered that the passage of a large flow of water may lead to erosion of earthen hydraulic structures.

1.4. Filling the water intake structure with water to a level at which the operation of the hydroelectric unit of a micro hydroelectric power station is possible should be a signal for opening the water supply to the turbine chamber. IMPORTANT: by the time the water supply to the turbine chamber is opened, it is necessary to make sure that debris, sand and stones do not get into the turbine chamber with water from the pressure basin. The flow rate of water supplied to the turbine during start-up should not exceed 20 percent of the nominal flow rate of the hydraulic unit with a gradual increase in flow rate to 50 percent of the nominal flow rate of the hydraulic unit. This flow is supplied to the turbine during the time specified in the operating instructions for the hydraulic unit. At the same time, the hydraulic unit operates without load during the start-up period.

1.5. Starting and stopping a hydroturbine, operation and maintenance (on the example of a radial-axial turbine HLD260-LJ-28 with a power of 30 kW). Model marking means the following:

• HL - mixed flow hydraulic turbine;
• D260 - impeller model;
• L - vertical axis;
• J - metal spiral chamber;
• 28 - nominal diameter of the impeller (28 cm).

Pre-operational preparation

1) Check whether the outlet of the discharge channel is located at the required depth under water (according to the requirements for the hydraulic unit).

2) Check whether all rotating parts are in a moving state.

3) Check that the bolts and nuts are tight.

4) Check whether the oil level is at the proper level (according to the requirements for the hydraulic unit).

5) Check whether all parts to be lubricated are sufficiently lubricated.

6) Check whether there are objects near the machine that could block the movement of its individual parts.

7) Check switchboard and wiring.

8) Open the top lock (sluice) and check if there is any leakage from the pressure pipe connections.

Release

1) Open the main gate so that the volute begins to fill with water. Then turn on the pressure gauge and vacuum gauge.

2) Slowly turn the speed control handwheel, start the pilot vane, and let the machine idle until the desired speed is reached. ATTENTION: it is necessary to ensure that the speed does not exceed the permissible limits.

3) Look at the frequency meter to see if it is stable at 50 Hz. When the unit reaches normal values, gradually increase the load and put the speed controller into self-control mode.

4) The degree of opening of the water distributor must be matched with the load of the power generator. It is adjusted by the speed control lever, taking into account the rotation speed of the generator.

Test run of the hydro turbine

Before putting the turbine into operation, it is necessary to run it in test mode and monitor the smooth operation of all its parts.

1) According to the start-up of the hydroturbine, first allow the unit's rotation speed to reach half of the required value. Run the turbine without load for 4 hours. Monitor whether there are any unforeseen phenomena in the operation of the unit. If everything is in order, increase the speed of revolutions to the required value and leave for continuous operation for another 4 hours.

2) After successfully running the turbine without load, gradually increase the load alternately by 25%, 50%, 75%, and up to full load. Once full load is reached, the unit must be tested for 72 hours (full load). Closely monitor the functioning of all parts of the unit. Record the operating status of the unit hourly. If everything is in order, put the unit into full operation. If, however, unexpected phenomena are detected during the test run, it is necessary to immediately stop the unit, identify and eliminate their cause.

Stopping the hydro turbine

1) Close the water distribution system.

2) Turn off consumers.

3) Close the water intake valve.

4) Turn off the pressure gauge and vacuum gauge.

5) Wipe the outside of the unit clean.

6) When the unit is stopped for a long time, or when it is iced up, it is necessary to open the drain valve located at the bottom of the spiral chamber, drain the accumulated water, and clean out the accumulation of impurities.

Emergency stop

If the following situations occur during the operation of the unit, it is necessary to immediately suspend its operation and make an appropriate entry in the operating log:

1) The power of the unit has significantly decreased.

2) The generator or speed controller is out of order.

3) Sharp vibrations of the unit, or unusual noise.

4) The bearing has overheated.

5) The unit "runs" to the sides (if the speed controller is in self-control mode, bring the operation to idle, and then stop).

2. Operating procedure under normal operating conditions

2.1. The operation of hydraulic structures should ensure the uninterrupted supply of water from the water intake structure to the diversion channel in the amount that ensures the operation of the hydraulic unit under load. A significant excess of water supply to the diversion channel can lead to dangerous washouts in the downstream.

2.2. In order to prevent damage to the diversion canal (especially if the canal is earthen), a very rapid change in the water level in the canal should not be allowed (for example, a large volume of water should be abruptly applied).

2.3. In order to prevent bank erosion, it is not allowed to pass water flows in excess of the allowable volume.

2.4. In order to prevent air from entering the turbine chamber, the set water level in the pressure basin must not be allowed to decrease. The ingress of air into the turbine chamber is a very dangerous phenomenon and can lead to water hammer of the turbine. In case of formation of funnels on the water surface in the pressure structure, it is necessary to reduce the water flow to the turbine and/or increase the water intake at the intake structure.

2.5. If the water basin is equipped with a water overflow and / or a discharge device, then the water supply can be increased. This will make it possible to have a supply of water in case of a sharp increase in water consumption by the hydroelectric unit and provide partial cleaning from litter floating on the surface.

2.6. Hydro turbine operation and maintenance:

1) Periodically check the tightness of various parts of the unit.

2) Periodically check the tightness of all nuts and bolts.

3) Monitor the serviceability and mobility of all moving parts of the unit.

4) Periodically measure the water pressure in the spiral chamber and the vacuum in the discharge channel, while recording the measurement data in the work log.

5) Make sure that cavitation corrosion does not form on the impeller blades.

6) Regularly fill in lubricating oil in the required places of the unit.

7) It is recommended to carry out a technical inspection and mini-repair of the unit every three months, and once a year to carry out a major overhaul. Significantly more frequent inspections of key parts such as the impeller, bearings, etc. are required.

8) Starting, operating and stopping the unit must be carried out in strict accordance with the prescribed procedure.

9) If a malfunction occurs during the operation of the unit, it is necessary to make an initial recording.

10) The production site must be kept clean. Spare parts, lubricants and consumables, tools must be present without fail.

2.7. The person operating the micro HPP must ensure a daily visual inspection of the hydraulic structures and the hydroelectric unit of the micro HPP, entering information on the results of the inspection into the Journal of Inspection and Observation of the Micro HPP. The log should contain the following information:

• the date of the inspection;
• data on measuring the level and volume of water in hydraulic structures;
• information about the presence of debris on trash-retaining mechanisms and the need to clean the mechanisms from debris;
• information about the presence of sediment in the traps and the need to clean them;
• information about the detected damage to the hydraulic structures of micro HPPs;
• date of shutdown of the micro hydroelectric power station and the grounds that caused such a suspension;
• other information provided for inclusion in the Journal of Inspection and Observation of Micro HPPs in accordance with the instructions.

In winter, information about icing of hydraulic structures and the presence (or absence) of sludge should be entered in the log.

3. Protection of the pressure pipeline and turbine from litter

3.1. During the operation of a micro HPP, it is necessary to ensure the protection of turbine equipment from floating litter (woody vegetation, grass, floating household waste, etc.).

3.2. The micro HPP protection system from litter should provide for the installation of litter-retaining mechanisms at all hydraulic structures along the path of water movement from the water intake structure to pressure pipelines. In order to protect the turbines of micro HPPs from litter that has entered the pressure basin, water from the pressure basin must pass through debris-retaining grates before entering the pressure pipeline.

3.3. The design and construction of the water intake structure of a micro hydroelectric power station (in a micro hydroelectric power station of a diversion type) is carried out in such a way as to ensure that most of the litter is cleaned by the flow of water into the river, preventing the litter from entering the diversion channel.

The design of the pressure basin should provide for a water organization system in such a way that the main flow of water directs litter into the waste conduit.

3.4. Cleaning of trash holding devices should be carried out regularly in order to prevent a decrease in the volume of water supplied to the turbine. At the time of the flood, cleaning of trash-retaining devices should be carried out more often than it is done during the normal operation of the micro HPP.

3.5. If a large amount of garbage is generated in the river on which the micro hydroelectric power station is built, then in order to avoid damage to the micro hydroelectric power station, it is permissible to stop the operation of the micro hydroelectric power station before the end of the flood period. In this case, the water intake from the water intake facility is suspended (this action, as a rule, is acceptable only for micro HPPs of the diversion type) and the operation of the equipment of the micro HPP is stopped.

3.6. Information about the cleaning of hydraulic structures from debris is entered in the log of inspection and observation of micro hydroelectric power plants.

4. Sediment control

4.1. Difficulties in the operation of micro hydroelectric power plants often arise due to silting of hydraulic structures and significant abrasive wear of turbine impellers. The design and construction of hydraulic structures for micro hydroelectric power plants should include the construction of various kinds of traps for stones, silt and sand.

4.2. The main sediment control measures are:

• carrying out bank protection works to prevent destruction and erosion of the banks of the diversion canal;
• installation of traps for stones, sand and silt along the route of water from the intake structure to the penstock;
• periodic removal of sediments in traps, and, if necessary, in the corresponding hydraulic structures.

4.3. If carrying out sediment removal can lead to the ingress of sand, and even more so stones, into the pressure pipeline, then it is necessary to suspend the operation of the micro hydroelectric power station during the cleaning of hydraulic structures from sediment.

4.4. Cleaning of traps and hydraulic structures from sediments should be carried out regularly. The frequency of cleaning depends on the rate of clogging of hydraulic structures and the sediment traps installed on them. Taking into account the natural and hydrological features of the rivers, as well as the differences between micro HPPs from each other (the absence of almost two identical micro HPPs), the owner of a micro HPP must independently determine the frequency of cleaning micro HPPs from sediments

4.5. Information about the cleaning of hydraulic structures from sediments is entered in the log of inspection and observation of micro hydroelectric power plants.

5. Skip floods (floods)

5.1. Every year, before the onset of the flood period, the owner of the micro HPP must determine the list of measures necessary for the normal passage of spring floods (floods).

5.2. In the case of a diversion type HPP, an important condition for the effective passage of floods is a properly designed and built water intake structure. The installation of the water intake structure is carried out in such a way that it is not in the path of the flood. It should be located on the inner bend of the river so that the main flood flow hits the opposite bank of the river, and not directly on the intake structure.

5.3. Destruction of hydraulic structures by floods due to the ingress of uncontrolled water flow into the diversion canal. The ingress of uncontrolled water flow as a result of a flood can occur when a new (additional) channel is formed upstream of the micro HPP or in the event of an increase in the river channel. To prevent such a situation, it is necessary to carry out work to strengthen the river bank in places of possible erosion, where a new riverbed may form, which will lead to the destruction of hydraulic structures and equipment of micro hydroelectric power plants.

5.4. In the case of small micro HPPs with a relatively small hydro unit, it makes sense to dismantle it and move it to a safe place.

5.5. The design and construction of hydraulic structures for micro HPPs should take into account information about the floods that were previously available on the river on which the construction of a micro HPP is supposed. This information can be obtained from the local population and relevant services (Ministry of Emergency Situations, Department of Water Resources, irrigation services). As the experience of passing through floods is accumulated, changes in the operating procedure for micro hydroelectric power plants during floods should be introduced into the operating instructions for micro HPPs.

5.6. After the passage of floods, all hydraulic structures, especially the downstream anchorages, as well as equipment, must be inspected, damages identified and the time frame for their elimination determined.

5.6. Information about floods, their start and end dates, as well as the results of their passage are entered into the inspection and observation log for micro hydroelectric power plants.

6. Operation at negative temperatures

6.1. Every year, before the onset of a period of negative temperatures, it is necessary to determine a list of measures for the normal passage of this period.

6.2. Before the period of negative temperatures, it is necessary to check:

• readiness for operation of gates intended for operation in the winter period, as well as serviceability of seals;
• readiness of sludge-discharge devices, grate-cleaning mechanisms (if any);
• serviceability of devices for heating and insulating gates, gratings, grooves, embedded parts and lifting mechanisms;
• serviceability of instrumentation;
• tools and devices (rakes, shovels, etc.).

It is also necessary to identify people for round-the-clock removal of ice, sludge and prepare for operation in the winter the premises in which the hydraulic unit is located in order to prevent freezing of equipment and instrumentation

6.3. Gates and hydraulic structures, for a period of negative temperatures, are subject to daily inspection for freezing.

6.4. The formation of even minimal congestion due to ice and ice masses in the diversion channel and pressure basin should not be allowed. When ice forms in hydraulic structures, it is necessary to immediately carry out work to remove it from the structures.

6.5. The fight against sludge and ice should be carried out in the following ways

• installation for the winter period of gratings with large spans between the rods.
• removal of sludge and ice from the pressure structure. Removal can be partially carried out through the waste conduit (if any), while care must be taken that the waste conduit does not become clogged;
• removal of sludge and ice by people using various kinds of devices: rakes, pitchforks, shovels, etc.;
• it is possible to install electric heating of trash-retaining grates in order to prevent the formation of ice on them.

6.6. To prevent blockage of the grates with sludge and floating ice, which can lead to a decrease in the volume of water entering the turbine, it is necessary to constantly clean the grate. Sludge is allowed to pass through the grate.

6.7. For the unhindered movement of sludge along the diversion channel, the following measures must be taken:

• micro hydroelectric power station should not operate at maximum load;
• all obstacles preventing the smooth and uniform movement of sludge must be removed to prevent the formation of congestion in the derivation.

6.8. In the log of inspection and observation of micro HPPs, places on the diversion canal where rapid glaciation occurs should be indicated for timely ice chipping in order to prevent the formation of ice jam.

6.9. In the event of a shutdown of a micro hydroelectric power station during a period of negative temperatures, it is necessary:

• drain water from the turbine chamber and pressure pipeline;
• close the access of water to these structures and mechanisms;
• close the gate in the water intake structure with the cessation of water supply to the diversion channel.

These measures are carried out in order to prevent the failure of the hydraulic unit and pressure pipeline.

Maintenance of hydraulic structures

Maintenance tasks are:

• continuous operational maintenance of hydraulic structures (inspections, elimination of minor defects, removal of debris and vegetation, clearing ditches, clearing snow in winter, etc.);
• monitoring of structures, conducting the necessary surveys and studies;
• identification of defects, the elimination of which requires repair work;
• maintenance of technical documentation for assessing the condition of structures.

7. Maintenance of hydraulic structures

7.1. During the operation of a micro hydroelectric power station, over time, cavitation damage (damage caused by water) may appear on concrete surfaces in the form of recesses, gullies, cracks, etc. This occurs due to the directed impact of water flows to certain places. When carrying out repair work on such surfaces, all damage that has occurred must be eliminated (walls are smoothed, protruding reinforcing parts (due to chipping off pieces of concrete) must be cut flush with the concrete surface or sealed to their original state.

If cracks are found in the body of the structure, it is necessary to determine the causes of their occurrence and carry out repair work to eliminate them.

7.2. During the operation of hydraulic structures made of soil materials, the formation of gullies, cracks, landslides, subsidence, soil washout is possible; it is necessary to determine the causes of their occurrence and carry out appropriate repair work.

7.3. On diversion canals, it is necessary to remove all obstacles that restrict the working section of the canal and cause pressure losses along the canal: unremoved remains of piles, supports of temporary bridges, remains of repair barriers, cofferdams, uncut bank ledges, etc.

7.4. If the canal crosses settlements, it is necessary to have descents for domestic water intake, equipped with additional safety measures in case of people falling into the water. The choice of water intake points must be agreed with the operating organization and local authorities.

7.5. Structures along the derivation route (seleduks, mudflow pipelines, stormwater discharges, upland ditches, and others) must be promptly cleared of sediment and silting and maintained in working order.

7.6. Planned shutdowns of micro HPPs should be used to inspect hydraulic structures, clean them from sediment and debris, and also to carry out repair work.

8. Frequently occurring malfunctions and ways to eliminate them (on the example of a radial-axial turbine HLD260-LJ-28 with a power of 30 kW)

Authors: Kartanbaev B.A., Zhumadilov K.A., Zazulsky A.A.

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