--- title: "Transmission and distribution planning procedure" subject: "Power Plant Design" chapter: 2 key: "semester_8/power_plant_design:planning-transmission-distribution" source: https://www.bctengineer.com/q/semester_8/power_plant_design/planning-transmission-distribution site: BCT Engineering --- # Transmission and distribution planning procedure Power Plant Design · Chapter 2: Integrated System Planning in Design Approach - Asked in: 2073 Bhadra, 6 marks - Video: [Introduction to Transmission Planning in urdu Hindi Language](https://www.youtube.com/watch?v=0fWUtGlcDmE) — Abdul Aziz Khan - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/power_plant_design/planning-transmission-distribution - Whole chapter: https://www.bctengineer.com/md/semester_8/power_plant_design/chapter-2 ## Question What do you mean by power system planning? Explain in detail Transmission expansion and distribution planning procedure. ## Short answer Power system planning determines the type, size, location, and timing of future facilities for reliable, least-cost supply. Transmission planning uses load flows and N-1 studies to select line and substation additions. Distribution planning forecasts spatial load, assesses feeders, and plans upgrades, capacitors, and automation to meet voltage/reliability targets. ## Answer **Power system planning** is the systematic process of deciding the future additions to generation, transmission and distribution facilities, with their type, size, location and time of installation, so that forecast load is supplied reliably, economically and with acceptable environmental impact. It has four linked parts: load forecasting, generation expansion planning, transmission expansion planning and distribution planning. #### Transmission expansion planning procedure 1. **Inputs:** Load forecast at each grid substation, generation expansion plan (where and when new plants come), existing network data, cross-border plans. 2. **Planning criteria:** N-1 security, voltage within ±5%, line loading within thermal limit, fault level within breaker rating, stability. 3. **Base-case studies:** Load flow for future years and seasons to identify overloads, low voltages and generation that cannot be evacuated. 4. **Candidate alternatives:** New lines, voltage upgrading (132 → 220/400 kV), double circuit, new substations, reactive compensation. 5. **Technical analysis:** Load flow, contingency, short-circuit and stability studies. 6. **Economic analysis:** Compare present worth of capital cost + loss cost + outage cost; choose least-cost plan. 7. **Implementation plan:** Routes, right-of-way, schedule and financing. #### Distribution planning procedure 1. **Spatial load forecast:** Forecast load by area/feeder using land use, new settlements and consumer growth. 2. **Study existing system:** Feeder loading, voltage drop, losses, reliability indices (SAIFI, SAIDI). 3. **Set criteria:** Voltage drop limit (e.g. 5–10%), feeder loading, loss target, reliability target. 4. **Substation planning:** Location and size of 33/11 kV substations; distribution transformer siting. 5. **Feeder planning:** New feeders, reconductoring, feeder reconfiguration, ring mains in cities. 6. **Loss reduction and reliability measures:** Capacitors, voltage regulators, automation, smart meters, underground cabling. 7. **Economic evaluation:** Choose the least-cost combination meeting the criteria. 8. **Implementation and review:** Phased construction; update every few years. ```text Load forecast | Generation planning --> Transmission planning | Distribution planning ``` **Example:** NEA's Kathmandu Valley distribution plan converts overhead lines to underground cables and adds new 132/11 kV substations to meet urban growth. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which are the four linked parts of power system planning? A. Billing, metering, tariff, audit B. Load forecasting, generation, transmission and distribution planning C. Protection, control, SCADA, metering D. Design, build, run, retire Answer: B. Planning links load forecast, generation expansion, transmission expansion and distribution planning. (Key point: Definition and parts) 2. Which is a candidate alternative in transmission planning? A. Reducing consumers B. Voltage upgrading (132 to 220/400 kV), double circuit, new substations, reactive compensation C. Removing generators D. Increasing load Answer: B. Alternatives include new or upgraded lines, substations and compensation. (Key point: Candidate alternatives) 3. How is load forecast in distribution planning? A. Spatially by area/feeder using land use, new settlements and consumer growth B. Only for the whole country C. Not needed D. Using fuel price Answer: A. Distribution planning needs area-wise load, so a spatial forecast is made. (Key point: Distribution forecast) 4. Which are reliability indices and loss/reliability measures in distribution planning? A. IRR and NPV; building dams B. LOLP and WASP; HVDC C. SAIFI and SAIDI; capacitors, regulators, automation, smart meters, underground cables D. MAPE; ANN Answer: C. Existing feeders are assessed with SAIFI/SAIDI and improved by capacitors, regulators, automation and cabling. (Key point: Reliability indices and measures) ## Related in Power Plant Design - [Transmission expansion planning procedure](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Atransmission-expansion-procedure) — Power Plant Design, chapter 2 - [Power system expansion planning for a utility](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aexpansion-planning-national-utility) — Power Plant Design, chapter 2 - [Generation and distribution planning procedure](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aplanning-generation-distribution) — Power Plant Design, chapter 2 - [Generation expansion planning procedure](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Ageneration-expansion-procedure) — Power Plant Design, chapter 2, asked 3× - [Transmission expansion planning in deregulated market](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Atransmission-planning-deregulated) — Power Plant Design, chapter 2 - [Transmission expansion planning and applicability](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Atransmission-expansion-applicability) — Power Plant Design, chapter 2 ## Related in other subjects - [Interconnected system and transmission planning](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Ainterconnected-system-planning) — Transmission and Distribution System Design, chapter 1 - [Planning of distribution; intermittent supply](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Adistribution-planning-intermittent) — Water Supply Engineering, chapter 7 - [T/F: X/R ratio, transmission vs distribution](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Atf-xr-ratio-transmission-distribution) — Transmission and Distribution System Design, chapter 1 - [Design steps and criteria of distribution system](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Adistribution-design-steps) — Water Supply Engineering, chapter 7, asked 3×