--- title: "Reservoir type hydropower plant schematic" subject: "Power Plant Design" chapter: 3 key: "semester_8/power_plant_design:reservoir-plant-schematic" source: https://www.bctengineer.com/q/semester_8/power_plant_design/reservoir-plant-schematic site: BCT Engineering --- # Reservoir type hydropower plant schematic Power Plant Design · Chapter 3: Hydro Power Plant Design - Asked in: 2079 Chaitra, 8 marks - Video: [Hydro power plant, Parts of Hydro plant, Components of Hydro plant #HydroPlant #PowerPlant](https://www.youtube.com/watch?v=3ixtdPORwsw) — Mechanical Engineering Management - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/power_plant_design/reservoir-plant-schematic - Whole chapter: https://www.bctengineer.com/md/semester_8/power_plant_design/chapter-3 ## Question Draw a schematic diagram of reservoir type hydro-power plant and describe necessary civil, mechanical and electrical components. ## Short answer Reservoir plant uses high dam storing monsoon water for dry season; civil: dam, reservoir, spillway, intake tower, headrace tunnel, surge tank, powerhouse, tailrace; mechanical: penstock, valve, turbine, governor, draft tube; electrical: generator, excitation, transformer, switchyard. Kulekhani-I is an example. ## Answer A **reservoir (storage) type** hydropower plant has a high dam that stores water in a large reservoir, usually for seasonal use. Water stored in the wet season is released in the dry season, so the plant can supply firm and peaking power all year. Kulekhani-I (60 MW) is Nepal's main example. #### Schematic ```text Reservoir (FSL) ~~~~~~~~~~~~ ~~~~~~~~~~~~~~~ |\ ~~~ storage ~~~ | \ High dam ~~~~~~~~~~~~~~~ | \ + spillway Intake tower -->|===\=============\ (MOL) |____\ \ Headrace tunnel [Surge tank] | | Penstock v Valve -> Turbine -> Generator | | Draft tube Transformer | | Tailrace Switchyard v v River Grid ``` #### Civil components 1. **Dam:** concrete gravity, arch or rockfill dam that creates head and storage. Full supply level (FSL) and minimum operating level (MOL) define the live storage. 2. **Reservoir:** stores water from the monsoon for the dry season; dead storage below MOL holds sediment. 3. **Spillway:** gated or ungated, passes the design flood safely. 4. **Intake tower:** draws water from various levels with trash rack and gates. 5. **Headrace tunnel:** pressure tunnel to the surge tank. 6. **Surge tank:** protects the tunnel from water hammer and supplies water on load rise. 7. **Diversion tunnel/cofferdam** (during construction), bottom outlet for emptying and flushing. 8. **Powerhouse** (surface or underground) and **tailrace**. #### Mechanical components 1. **Penstock** with anchor blocks; **main inlet valve** (butterfly or spherical). 2. **Turbine:** Francis for medium head or Pelton for high head (Kulekhani uses Pelton). 3. **Governor:** keeps frequency constant by controlling flow. 4. **Draft tube** (reaction turbines), cooling water, oil and compressed air systems, EOT crane. #### Electrical components 1. **Synchronous generator** with **excitation system and AVR**. 2. **Generator circuit breaker** and bus duct. 3. **Step-up transformer** and **switchyard** (breakers, isolators, CT, PT, lightning arresters). 4. **Station service:** station transformer, DC battery, diesel generator for black start. 5. **Protection, control and SCADA**; **earthing mat**. #### Features Reservoir plants give firm power, peaking and frequency regulation, but have high cost, long construction time, resettlement and sedimentation problems. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Why does a reservoir plant give firm power all year? A. It uses only the instantaneous river flow B. Wet-season water is stored and released in the dry season C. It has no need of a dam D. It relies on diesel backup Answer: B. Seasonal storage holds monsoon water for dry-season generation. (Key point: Reservoir purpose) 2. What do FSL and MOL define? A. The penstock diameter B. The tailwater level C. The live storage; dead storage below MOL holds sediment D. The spillway capacity only Answer: C. Live storage lies between FSL and MOL; below MOL is dead storage for sediment. (Key point: Live and dead storage) 3. What is the advantage of an intake tower? A. It removes the need for a surge tank B. It spills floods C. It stores sediment D. It can draw water from various levels, with trash rack and gates Answer: D. A tower with openings at several levels draws water as the reservoir level changes. (Key point: Intake tower) 4. Which is a drawback of reservoir plants? A. High cost, long construction, resettlement and sedimentation B. Cannot supply peaking power C. Cannot regulate frequency D. Output depends wholly on daily inflow Answer: A. They give firm power and peaking but are expensive and cause submergence and sedimentation. 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