Advantages of interconnected power system

An interconnected power system is a network in which two or more generating stations or control areas are connected by transmission lines (tie-lines) and operate in parallel at the same frequency, sharing generation and load. A national grid such as Nepal's INPS, which is also tied to India, is an example.

Advantages over an isolated power system

1. Higher reliability: when a generator or plant fails, other plants supply the load through tie-lines.
2. Reduced reserve capacity: spinning reserve is shared, so each station needs less standby capacity.
3. Diversity of loads: peaks of different areas occur at different times, so total installed capacity is lower and load factor is better.
4. Economic operation: cheaper sources (hydro, base-load plants) are used fully and costly units only at peak; economic load dispatch across the whole system.
5. Larger, efficient units: bigger machines with lower cost per kW can be installed.
6. Exchange of surplus power: extra energy (e.g. wet-season hydro) can be exported and deficit imported.
7. Better frequency regulation: large combined inertia keeps frequency more stable for a given load change.
8. Easier maintenance: units can be shut down for overhaul without load shedding.

A short drawback note: fault levels rise and faults can spread, so better protection and coordination are needed.