--- title: "Schematic of a PROR hydropower plant" subject: "Power Plant Design" chapter: 3 key: "semester_8/power_plant_design:pror-schematic-components" source: https://www.bctengineer.com/q/semester_8/power_plant_design/pror-schematic-components site: BCT Engineering --- # Schematic of a PROR hydropower plant Power Plant Design · Chapter 3: Hydro Power Plant Design - Asked in: 2077 Chaitra, 8 marks; 2075 Bhadra, 6 marks (asked 2 times) - Video: [Components of Hydroelectric Power Plant | Hydroelectric Power Plant | Power Pant | Fluid Mechanics](https://www.youtube.com/watch?v=MSR7Acw_Q6U) — Professor Nidhi Trivedi - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/power_plant_design/pror-schematic-components - Whole chapter: https://www.bctengineer.com/md/semester_8/power_plant_design/chapter-3 ## Question Draw a schematic diagram of PROR type hydropower plant showing all the necessary components and describe each of them. ## Short answer A PROR plant uses a diversion dam with pondage for a few hours of storage, allowing peaking operation. Key components: intake with trash rack, desander, headrace tunnel, surge tank, penstock, powerhouse with turbine and generator, tailrace, transformer, and switchyard. ## Answer A **Peaking / Pondage Run-of-River (PROR)** plant is a run-of-river scheme with a small daily storage (pondage) behind the diversion dam. Water is stored during low-demand hours and used to generate full power during peak hours. It combines the low cost of ROR with peaking capability. #### Schematic ```text River ->[ Diversion dam + radial gates ]-> Spillway | Pondage (few hours storage) | +------------------------------+ | | [Intake + trash rack] Riparian | release [Gravel trap / Desander] | Headrace tunnel -------> [Surge tank] | Penstock / shaft | +----------[ Powerhouse ]----------+ | MIV -> Turbine -> Generator | | Governor, Exciter, Control room | +----------------------------------+ | | Tailrace Transformer | | River Switchyard -> Line ``` #### Description of components 1. **Diversion dam/weir:** Concrete or rockfill structure across the river that raises the water level and creates the pondage. Gates control water level. 2. **Pondage:** Small reservoir that stores water for a few hours (e.g. 4–6 h) so that the plant can run at full capacity during the evening peak. 3. **Spillway and undersluice:** Spillway passes flood flow safely; undersluice flushes sediment from the pondage. 4. **Intake:** Admits the design discharge into the water conductor; has a trash rack to stop debris and gates for closing. 5. **Desander (settling basin):** Settles sand and silt so that turbine runners are not eroded. 6. **Headrace tunnel/canal:** Conveys water from intake to surge tank at a gentle slope. 7. **Surge tank:** Vertical shaft that absorbs water hammer when turbines close suddenly and supplies water when load increases. 8. **Penstock/pressure shaft:** Steel or lined pipe that carries water under high pressure to the turbines; branches into each unit. 9. **Powerhouse:** Building housing main inlet valves, turbines (Francis/Pelton depending on head), generators, governors, excitation, control and protection equipment, cranes and auxiliaries. 10. **Turbine:** Converts the energy of water into mechanical rotation. 11. **Generator:** Synchronous machine converting mechanical power to electrical; excitation and AVR control voltage. 12. **Tailrace:** Channel or tunnel that returns water to the river. 13. **Transformer and switchyard:** Step up the generator voltage (e.g. 11 kV to 132 kV) and connect the plant to the transmission line with breakers, isolators and arresters. 14. **Auxiliary systems:** Station service transformer, DC battery, diesel generator for black start, cooling water, fire protection, SCADA. **Examples in Nepal:** Kaligandaki A (144 MW), Middle Marsyangdi (70 MW), Upper Tamakoshi (456 MW) are PROR plants. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. The pondage of a PROR plant stores water for: A. A few hours (e.g. 4-6 h) so the plant runs at full capacity in peak hours B. Several months for dry season C. Flood control only D. Sediment disposal only Answer: A. It is small daily storage used for the evening peak. (Key point: Pondage purpose) 2. The trash rack at the intake: A. Increases head B. Stops floating debris from entering the water conductor C. Settles sand D. Absorbs water hammer Answer: B. Trash racks keep debris out, and gates allow closing. (Key point: Intake) 3. The penstock is: A. An open canal at gentle slope B. A steel or lined pressure pipe carrying water to the turbines and branching to each unit C. A vertical shaft open to the air D. The tailrace channel Answer: B. It carries high-pressure water from the surge tank to turbines. (Key point: Penstock) 4. The transformer and switchyard: A. Step up generator voltage (e.g. 11 to 132 kV) and connect to the transmission line B. Step down voltage to the generator C. Store energy D. Control the water level Answer: A. The generator step-up transformer raises voltage for transmission. (Key point: Transformer) ## Related in Power Plant Design - [Reservoir type hydropower plant schematic](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Areservoir-plant-schematic) — Power Plant Design, chapter 3 - [PROR environmental impact and schematic](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Apror-environmental-impact) — Power Plant Design, chapter 3 - [ROR versus PROR hydropower plants](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aror-vs-pror) — Power Plant Design, chapter 3 - [Hydropower plant components and functions](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Ahydropower-components-functions) — Power Plant Design, chapter 3, asked 2× - [Sketch of a medium head PROR plant](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Apror-medium-head-sketch) — Power Plant Design, chapter 3, asked 2× - [High dam hydropower project components](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Ahigh-dam-components) — Power Plant Design, chapter 3 ## Related in other subjects - [Combined plant components and T-s diagram](https://www.bctengineer.com/question.md?key=semester_7%2Fpower_plant_equipment%3Acombined-components-ts) — Power Plant Equipment, chapter 8, asked 4× - [Schematic diagram of rural gravity scheme](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Arural-gravity-scheme-diagram) — Water Supply Engineering, chapter 1, asked 5× - [Layout of hydropower scheme components](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Ahydropower-scheme-layout) — Hydro Power, chapter 5 - [Steady state operation of hydropower plant](https://www.bctengineer.com/question.md?key=semester_7%2Fpower_plant_equipment%3Ahydropower-steady-state-operation) — Power Plant Equipment, chapter 1