---
title: "Transmission expansion planning and applicability"
subject: "Power Plant Design"
chapter: 2
key: "semester_8/power_plant_design:transmission-expansion-applicability"
source: https://www.bctengineer.com/q/semester_8/power_plant_design/transmission-expansion-applicability
site: BCT Engineering
---

# Transmission expansion planning and applicability

Power Plant Design · Chapter 2: Integrated System Planning in Design Approach

- Asked in: 2079 Shrawan, 4 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/power_plant_design/transmission-expansion-applicability
- Whole chapter: https://www.bctengineer.com/md/semester_8/power_plant_design/chapter-2

## Question

What is transmission expansion planning? Discuss its applicability.

## Short answer

Transmission expansion planning determines new lines and substations with voltage, capacity, and timing to deliver power reliably at minimum cost. It applies to evacuating generation, meeting load growth, ensuring N-1 security, reducing losses, enabling cross-border trade, and coordinating with other plans.

## Answer

**Transmission expansion planning (TEP)** is the process of deciding which new transmission lines, substations and transformers should be built, with their voltage, capacity, route and commissioning year, so that power from present and future generators reaches the load centres reliably and at minimum cost over the planning horizon (10–20 years).

#### Main questions answered
- **Where** to build new lines/substations?
- **What** voltage level and conductor/capacity?
- **When** to commission them?

#### Applicability
1. **Evacuation of new generation:** New hydro plants in remote valleys need lines to the grid; without TEP, energy is spilled (a common problem in Nepal).
2. **Meeting load growth:** Supplies growing cities and industrial corridors without overloading existing lines.
3. **Reliability and security:** Ensures N-1 security, voltage limits and acceptable fault levels.
4. **Loss reduction:** Higher voltage (220/400 kV) reduces $I^2R$ losses.
5. **Cross-border trade:** Plans interconnections such as Dhalkebar–Muzaffarpur and Butwal–Gorakhpur 400 kV for export/import.
6. **Market operation:** Removes congestion, allows open access for IPPs in a deregulated market.
7. **Coordination:** Links generation expansion plan with distribution plan; avoids stranded generation or idle lines.

Example: NEA's Transmission System Master Plan identifies river-basin-wise 400 kV corridors (Koshi, Gandaki, Karnali) to evacuate planned hydro projects.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. TEP determines for new lines
   A. only the colour
   B. voltage, capacity, route and commissioning year
   C. only fuel type
   D. only consumer tariffs
   Answer: B. TEP answers where, what voltage/capacity and when. (Key point: Definition)

2. Why is TEP needed for new hydro plants in remote valleys?
   A. To avoid building the plant
   B. To raise voltage drop
   C. To reduce rainfall
   D. To connect them to the grid, otherwise energy is spilled
   Answer: D. Without lines, the generated energy cannot be evacuated and is spilled. (Key point: Evacuation)

3. How does higher transmission voltage (220/400 kV) help?
   A. It reduces I^2R losses
   B. It raises current
   C. It increases losses
   D. It lowers insulation
   Answer: A. For the same power, higher voltage gives lower current and hence lower I^2R loss. (Key point: Loss reduction)

4. What does TEP do in a deregulated market?
   A. Increases congestion
   B. Restricts IPPs
   C. Removes congestion and allows open access for IPPs
   D. Stops cross-border trade
   Answer: C. It supports fair competition by removing congestion and ensuring open access. (Key point: Market/coordination)

## Related in Power Plant Design

- [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 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
- [Transmission and distribution planning procedure](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aplanning-transmission-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×
- [Generation expansion planning and load forecasting](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Ageneration-expansion-load-forecast) — 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