Balancing Supply and Demand in Electricity Grids
Introduction
Throughout the day, electricity demand fluctuates greatly, depending on the time of day and consumption, as well as the weather and the season. Similarly, electricity supply can fluctuate as more and more intermittent renewable energy sources are added to the grid. However, supply and demand need to be balanced to keep electricity grids reliable and stable, and to avoid shortages or blackouts.
Measuring and Managing Imbalances
In Europe, the equilibrium point for the European grid, which operates on alternating current, is at a frequency of 50 Hertz. In the USA, the reference frequency is 60 Hertz. Grid operators ensure that this frequency remains stable 24 /7, with a tolerance threshold of plus or minus 0.050 Hertz.[1]
Changes in grid frequency immediately show if there is an imbalance and also signal its degree of severity.
An imbalance in the grid could be either:
- High electricity generation and low electricity demand
- Low electricity generation and high electricity demand
High Electricity Generation and Low Electricity Demand
If too much electricity is fed into the grid in relation to consumption, the electrical frequency increases. This can be managed by reducing generation through taking power plants off the grid. For example, wind farms are disconnected when the wind is strong and demand for electricity is low.[2]
Low Electricity Generation and High Electricity Demand
When power generation is too low to meet demand, frequency drops. This can be managed by increasing inputs such as steam, fuel or water to increase power output. Grid-connected power stations usually have their own reserve capacity to increase electricity production. [1] Gas plants can be dispatched at times of peak demand. It can also be managed by reducing demand, e.g. from industrial users who regulate their production for a period of time and receive compensation. Finally, load shedding is also an option to restore balance and avoid blackouts.[2]
Storage Options
In order to cope with both high and low load situations, the storage of electricity is of great importance. However, the large-scale storage of electricity in the grid is still a major challenge and subject to research and development.
Read the article about grid energy storage.
Regional Interconnections
Interconnections between regions can balance out fluctuations in renewables production. Surplus electricity can also be sold to other countries or power can be purchased from other electricity markets in times of high demand.
Further Information
- Grid Portal on energypedia
- Flexibility (Power System)
References
- ↑ 1.0 1.1 Power grid in a changing world; accessed in November 2024
- ↑ 2.0 2.1 Why does the electricity grid have to stay in balance? retrieved October 2024
