The National Grid is an incredible feat of modern engineering. It is a vast and intricate network that ensures we have a reliable and efficient distribution of electricity across the entire country. The National Grid is responsible for delivering power to homes, businesses, and industries. The electricity that comes into the National Grid comes from a variety of sources, such as from panels that Solar Panel Installation Bristol companies install. Here’s how it works.
Electricity generated through a variety of sources is generated at power stations in the form of high-voltage alternating current or AC. In order to minimise the amount of energy lost during transmission, the AC voltage is passed through transformers. High-voltage electricity is much more efficient at being transmitted over longer distances. The transformers are responsible for the increased voltage of the AC.
At this point, the electricity enters the transmission network, which is a network of high-voltage overhead lines, substations and underground cables. The transmission network covers the entire UK and is responsible for carrying the electricity from the power stations to the local distribution points. During this journey, the electricity passes through substations where the voltage is decreased to make it safe for transmission.
Once the voltage has been reduced, the electricity is distributed to the local distribution networks and then to homes and businesses. Here, it is used to power our devices and domestic appliances. Over time, the original source of the electricity will move further away from fossil fuels and closer to more sustainable methods.
Where the electricity on the grid comes from
The grid carries power from many different sources, and most of them work in a similar way. In gas, coal and nuclear power stations, fuel is used to create heat. Gas and coal are burned, while in a nuclear plant uranium fuel pellets release heat as their atoms split. That heat produces steam or hot gas, which drives a turbine, and the turbine turns a generator that converts mechanical energy into electricity.
Wind turbines skip the heat stage. The wind turns the blades, which drive a generator, rather like a giant version of a bicycle dynamo. Transformers then adjust the electricity to the right voltage before it enters the grid.
Solar panels work differently again. Sunlight striking the cells sets electrons flowing, and the panel combines the output of many cells into a larger current. Homes with solar panels can export the power they do not use back to the grid, where it is shared out across the country.
When too much power leads to negative prices
Balancing a grid works in both directions, and surplus can be as awkward as shortage. On one sunny, windy weekend in May, Germany met 87% of its electricity demand from renewable sources at the peak. Demand for power from nuclear, coal and oil stations fell sharply, but those plants cannot change their output quickly enough to keep pace with sudden surges from wind and solar.
The result was more electricity entering the grid than consumers were taking out, which risks overloading the system. Grid operators handle this by cutting prices when demand is low and production high, to encourage more use. In extreme cases the price for large industrial users can drop below zero, so they are effectively paid to consume electricity. For a short time, the more power those businesses used, the more they earned, and the network was protected from damage.
How transformers step voltage up and down
Transformers are what make a national grid possible. Some power is always lost as electricity travels along wires, and the higher the voltage, the smaller the share that is lost. So transformers step the voltage up for long distance transmission, with power lines carrying hundreds of thousands of volts. Before the electricity reaches homes and businesses, other transformers step it back down. Heavy industrial machinery may need 10,000 volts or more, while household appliances are typically rated somewhere between 110 and 250 volts.
They work by electromagnetic induction. Current flowing through a wire creates a magnetic field, and when that field fluctuates around a second coil of wire, it generates a current in that coil too. Changing the number of turns in each coil makes the output voltage higher or lower than the input.
Winding the coils around a core, often of soft iron, makes the process more efficient. Cores are either laminated or toroidal. Toroidal cores are smaller, quieter and produce less stray magnetism.