Transformers play a vital role in the national power grid, which is mainly reflected in the following aspects:

1. Voltage conversion: Transformers can convert high voltage into low voltage, or convert low voltage into high voltage. This is very important for long-distance power transmission, because high voltage can reduce line losses and improve power transmission efficiency.

2. Improve transmission capacity: By increasing the transmitted voltage, the power that can be transmitted by the same wire can be increased, thereby improving the transmission capacity of the entire power grid.

3. Distribution and regulation: In the power distribution system, transformers are used to reduce the high voltage on the main line to a level suitable for users so as to safely supply electricity to households and industries.

4. Phase adjustment: Some types of transformers (such as phase-shift transformers) can adjust the phase to achieve load balancing and improve system stability.

5. Isolation protection: The transformer can also provide a certain degree of isolation protection to prevent the propagation of faults and ensure the safety of equipment and personnel.

6. Support renewable energy access: With the development of renewable energy, transformers also play an important role in connecting distributed power generation systems such as wind power and solar power, helping to regulate power supply from different sources.

In short, transformers are an indispensable and important equipment in the national power grid. They not only improve the reliability of power supply, but also ensure that all types of users across the country can obtain stable and safe electricity services.