Power system expansion planning for a utility

Power system expansion planning is the long-term (10–25 years) process of deciding the least-cost additions of generation, transmission and distribution facilities, with their type, size, location and timing, to meet the forecast load with a required level of reliability.

Components

1. Load forecasting: peak demand and energy by year and region.
2. Generation expansion planning: which plants to build and when.
3. Transmission expansion planning: new lines and substations to carry power.
4. Distribution planning: feeders and substations to supply consumers.
5. Financial and environmental analysis.

Applicability for a national utility (e.g. NEA)

• Meeting future demand: A national utility must ensure that capacity grows ahead of demand; NEA's load forecast shows demand rising quickly due to EVs, cooking and industry.
• Least-cost mix: It chooses the right combination of ROR, storage, pumped storage, solar and import so that both wet-season and dry-season needs are met. Nepal's heavy ROR share causes wet-season surplus and winter deficit; expansion planning recommends storage projects to fix it.
• Transmission backbone: It identifies corridors (e.g. 400 kV east–west and north–south lines) and cross-border links for export.
• Reliability target: It sets reserve margin and N-1 security so that load shedding is avoided.
• Investment and tariff: It gives the basis for borrowing from donors (ADB, World Bank), for PPAs with IPPs and for tariff approval by the regulator.
• Coordination: It aligns national policy (Energy Roadmap, about 28,500 MW by 2035), private sector and regional trade.
• Timing: Hydro projects take 5–10 years to build, so decisions must be taken early.

Without expansion planning a utility either faces shortage and load shedding (as Nepal did before 2016) or idle capacity and energy spill.