What are checked during safety inspections of hydropower stations?

1. Safety inspection of factory area and factory building

(1) Verification of design standards

1. Check the flood prevention design standards of the main power plant, auxiliary power plant, main transformer site, switch station, outlet yard and access roads (holes) of the hydropower station.

2． Check whether the top elevation of the flood control embankment (wall) of the shore-type above-ground factory building is higher than the upstream water level of the river corresponding to the flood of the factory building.

(2) Overall layout inspection

1. Check the locations of underground factory traffic shafts, busbar shafts, and ventilation and smoke exhaust hole (well) exits.

2． Investigate the impact of flood discharge rain and mist areas, discharge flood jump areas and jet areas, and accidental water flows in pressure pipes on the entrances of traffic tunnels, traffic shafts, busbar shafts, ventilation and smoke exhaust tunnels (wells) exits, and entrances and exits of ground or underground factories. .

3. Investigate the possibility and consequences of debris flow caused by all gullies on the slopes around the factory area, as well as the blocking and drainage measures.

4. Check the location, size, elevation of holes, pipe trenches, passages, reserved gaps, etc. that connect upstream and downstream or rivers (which may cause flooding of the factory building), as well as their sealing and drainage measures.

5． Check the elevation of the tailrace gate operating corridor or operating platform.

6． Investigate the flood prevention measures at the entrance to the traffic tunnel of the underground factory and the settings for safe entry and exit passages for personnel.

7. Check the layout of the tailrace channel of the shore-type ground-level powerhouse, as well as the protection measures and plans against erosion or siltation.

8. Check the length and height of the upstream and downstream diversion walls between the riverbed factory building and the drainage building.

9. Investigate the installation, operation and management of flood control doors connecting the factory building and the dam corridor.

(3) Factory structural safety inspection

1. Check the structural integrity of the factory roof and the smooth drainage.

2． Check the structural integrity and operating form of the retaining walls upstream and downstream of the ground powerhouse to see if there are any cracks, leaks, etc.

3. Check the integrity of the concrete structure outside the volute of the factory building to see if there are any cracks, leaks and other safety hazards.

4. Check whether there are any leaks in the water sealing of the transverse joints of the river bed type factory building.

5． Check the stability of the flood control embankment (wall) of the shore-type ground-level powerhouse and the condition of the foundation.

6． Check the sealing and operation of the sealing structures of construction branch tunnels, geological tunnels, etc. in the underground factory system that are connected to reservoirs or water conveyance tunnels, or whose exits are below the flood level of the factory.

7. Check the processing and operation conditions of large geological structural zones, fault fracture zones, joint and fissure development areas, goaf areas and groundwater enrichment areas, large karst caves, underground rivers, etc. (if any) in the main caverns of the underground powerhouse.

(4) Safety inspection of the reservoir bank and rivers upstream and downstream of the factory building

1. Check the overall stability of the reservoir bank slope.

2． Check the overall stability of the river bank and back slope upstream and downstream of the factory building.

3. Check the riverbed downstream of the factory for siltation, blockage and illegal occupation.

4. Verify the water level-flow relationship of the riverbed at the plant site.

5． Check whether the return water from the downstream cascade power station supports the water level downstream of the factory building.

2. Safety inspection of water diversion system

1. Check the pipelines and equipment connected to the reservoir, water inlet, and water diversion system, and check the integrity of the expansion joints.

2． Check the deformation and cracks of the open water diversion pipes before entering the factory and on the back slope (non-destructive testing if necessary), the deformation and water seepage of steel pipe welds and expansion joints, the deformation of the steel pipe support structure, and both sides of the open pipe bed Slope deformation, whether the drainage system is smooth and measures to prevent debris flow, etc.

3. Check the deformation and water seepage (pressure) of the water diversion buried pipes, plugging bodies, and pressure regulating well structures; the water seepage and changes in the high-pressure pipeline drainage system and the external drainage system of the pipeline; the actual highest surge and working conditions of the pressure regulating well.

4. Check the structural deformation and seepage pressure of the buried pipes in the dam, as well as the deformation and water seepage of the back and exposed pipes behind the dam.

5． Check the seepage pressure and deformation of the buried pipe section in front of the underground factory, the deformation, deformation, welding and expansion joint deformation, water seepage, etc. of the exposed pipe in the inlet section, the water seepage and changes in the high-pressure pipeline drainage system and steel pipe external drainage system in front of the factory.

6． Check the structural integrity and water seepage of the entrance accident maintenance gate and working gate slot.

3. Safety inspection of hydraulic transition process of water transmission and power generation system

1. Check the results of the hydraulic transition process review and calculation by the design unit and the main engine supplier after the unit load rejection test.

2． After the unit is overhauled, check the load rejection test results of the unit and check the guide vane closing rule settings.

3. Check the results of the re-calculation of the hydraulic transition process after capacity expansion and transformation (if any).

4. Safety inspection of tailrace system

1. Check the pipelines and equipment connected to the tailwater system and downstream rivers.

2． Check the structural integrity of the concrete structure of the tailrace outlet gate slot, water seepage, and the elevation of the vent hole opening.

3. Check the deformation and seepage pressure of the tailrace pipeline; the structural deformation and water seepage (pressure) of the plugging body and pressure regulating well connected to the factory building, the changes in water seepage in the drainage system, and the actual highest surge and pressure in the tailrace pressure regulating well. working conditions.

5. Metal structure safety inspection

1. Check the water blocking and dynamic water closing functions of the emergency (fast) gate at the water inlet of the diversion tunnel of the power station, and conduct a remote operation test in the central control room.

2． Check the water blocking and dynamic water closing functions of the gate valve-type tailwater accident gate and the lower reservoir inlet and outlet accident gate of the pumped storage power station, and conduct remote operation tests in the central control room. Check the gate chamber inspection rules and records of the gate valve-type tailrace accident gate, and check the regular inspection and update status of the connecting bolts of equipment withstanding high water heads.

3. Check the water blocking, opening and closing functions and operating status of flood control gates in factories, corridors and other places.

4. Check and review the consistency of the design water level of the hydropower station's tailwater maintenance gate and the flood design standards of the power plant.

6. Safety inspection of the unit and its ancillary equipment

1. Check the operating stability of the unit, ensure that the vibration, swing, and pressure pulsation values ??of the unit are within the allowable range, and check the operating status of the vibration protection device.

2． Check the formulation and implementation of stability testing of power station units and stability operation scheduling rules.

3. Check the water inlet valve of the hydroelectric generator unit (pumped storage unit), unit shaft system, top cover and seat ring, top cover split surface, volute inlet door, draft pipe inlet door, etc.; tubular unit flow path Cover plate, water guide ring, runner chamber and entrance door of the runner chamber, etc.; connection of water distribution ring pipe, nozzle, nozzle and other parts of the impact unit, service life of fixed bolts, non-destructive testing results and replacement records. Check the tightening status and integrity of prestressed bolts.

4. Check the integrity of the expansion joints and welded joints of the internal pipelines of the unit.

5． Check the drainage capacity and operating status of the roof drainage facilities and drainage channels.

6． Check the spindle seal wear and water leakage.

7. Check the sealing operating status and water leakage of the expansion joint connected to the volute, and conduct non-destructive testing of the expansion joint regularly.

8. Check the operating status of the water inlet valve and its extension section, expansion joint and volute open pipe section, and conduct non-destructive testing and/or stress testing regularly.

9. Check the operating status and accuracy of the segmented closing device and overspeed limiter of the speed control system.

10． Check the test results and operating status of electrical and mechanical overspeed protection devices.

11. Check the dynamic water closing function test of the water inlet valve and conduct a simulation test.

7. Drainage system safety inspection

1. Check the operation status and equipment integrity of the factory drainage system, leakage drainage system, and maintenance drainage system; check the factory building leakage, maintenance water collection well volume, drainage capacity, and operation and maintenance status.

2． Check whether the check valve at the outlet of the drainage system pump is a slow-closing check valve and its integrity.

3. Check the operation of the surface water and groundwater drainage systems on the surface and slopes around the factory area (whether the water interception is effective, whether the drainage is smooth, and whether the drainage capacity meets the requirements).

4. Check the setting and operation of drainage channels for factory maintenance, water leakage, and large-flow drainage on the ground inside and outside the factory.

5． Check the leakage of the surrounding rock of the underground factory and the groundwater level outside the factory.

6． Check the condition of other water supply pipelines and related control valves in the factory area (such as local drinking water, irrigation, etc.).

8. Security inspection of control and protection communication system

1. Check the protection water level annunciator of the flooded factory building at the lowest level of the main factory building and other important parts, as well as its action rules and test results.

2． Check the water level monitoring device of the water collection well in the factory building and the high water level alarm signal transmission channel.

3. Check the reservoir water level measurement control device and reservoir water level data communication channel. Pumped storage power stations need to have technical measures to prevent the reservoir water level under pumping conditions and the reservoir water level under power generation conditions from exceeding warning values.

4． Check the station network settings of the water regime forecasting and reporting system and the communication method of the automatic forecasting and reporting system.

5. Check the protection action logic and circuit reliability of the independent hard-wired emergency operating system flooded plant alarm signal for unit shutdown and emergency gate closing.

6. Check that the emergency operation button box installed in the central control room can directly shut down the unit and close the accident gate through a hard-wired circuit independent of the monitoring system in an emergency. Check and verify that the operating power supply should be independent and reliable, and conduct simulation tests.

7. Check the generator floor escape channel to manually start the flooded factory button. In an emergency, it can directly shut down the unit and close the accident gate through a hard-wired circuit independent of the monitoring system. Verify that the operating power supply should be independent and reliable, and conduct simulation tests.

8． Check the functions of the sound and light, alarm bell and other alarm systems of the independent flooded factory in the factory.

9. Check the reliability of the power supply of the main water inlet valve control circuit, and verify the dual-circuit redundant control function of "power on and off" and "power off and off" on the main water inlet valve.

10． Check the reliability of the power supply of the speed regulator control loop, and verify the "power-on shutdown" and "power-off shutdown" dual-circuit redundant control functions of the speed controller.

11. Check the reliability of the control power supply of the reservoir inlet and outlet accident gate and tailwater accident gate. The emergency closing command should directly act on closing the gate without going through the PLC.

12. Check the electrical locking function between the tailwater accident gate and the main water inlet valve of the pumped storage power station: the water inlet valve is fully closed to allow the tailgate operation, and the tailgate is fully closed to lock the ball valve operation.

13． Check the clock synchronization function of the power station monitoring system, excitation system, speed control system, protection system, fault wave recording device and other equipment, and verify the wave recording and real-time recording and storage functions and power-off storage function of the above equipment.

9. Safety inspection of factory electrical system

1. According to the requirements of Articles 3.1.1 to 3.1.6 of the "Power Design Regulations for Hydropower Plants" (NB/T35044-2014), check the connection methods, operating status and equipment of the working power supply, backup power supply and security power supply of the plant power system. Integrity.

2． Check the reliability of the power supply of the leakage and drainage system of the factory under normal and accident conditions.

3. Check the regular start-up records of the diesel generator set.

4． According to the requirements of the "Lighting Design Specification for Hydroelectric Power Plants" (NB/T35008-2013), check the normal lighting and emergency lighting configuration of traffic entering the plant and emergency escape routes.

10. Industrial TV system safety inspection

1. Check the waterwheel room, main water inlet valve, leakage collection well, corridor and water level signal, volute entrance door, tailwater entrance door, reservoir water level scale, upper/lower reservoir gate well, tailrace gate well, Industrial TV settings and operating status in important parts such as diesel generator rooms.

2． Check that the protection level of fixed industrial TV cameras in important parts is not lower than IP67, they should bring their own large-capacity memory cards, and the UPS power supply time of industrial TV system equipment is not less than 1 hour.

11. Inspection of the emergency plan for flooded factory buildings

Inspect the pertinence, completeness, operability, preparation, update, drills and material preparation of the emergency plan to prevent flooded factory accidents state.

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