Cilfynydd Synchronous Condenser
Construction Phase Information and Latest News
Background
Over the past 20 years the UK power system has undergone a significant decarbonisation replacing electricity generated from coal and gas fired power stations with renewable energy from solar PV, onshore and offshore wind. The percentage of electricity generated from coal has fallen from over 60% to less than 3% over the past 20 years. Over the same period the proportion of electricity generated from wind and solar has increased from 0% to over 15%.
This changing pattern will continue with the UK’s final coal fired power station closing in 2024 and significant volumes of additional renewable generation planned to come online. This is all driven by the UK’s binding legal commitment to achieve net zero carbon emissions by 2050.
Traditional power grids rely on synchronous generators (coal, gas and nuclear), which inherently provide stability through inertia and control of grid frequency and voltage. These generators are physically coupled or synchronised to the electricity grid and are able to provide stabilising properties as a byproduct of generating electricity.
Renewable generators such as wind and solar are connected to the grid via power electronics and are described as asynchronous. They do not offer the same stabilising properties as more traditional forms of electricity generation. When a significant portion of electricity generation comes from renewable sources, which are often asynchronous, it can be more challenging to control and maintain stable grid frequency and voltage.
To address these stability challenges, grid operators are investing in grid modernisation, energy storage, advanced control systems and grid infrastructure upgrades to ensure that the increasing share of renewables can be integrated while maintaining a reliable and stable power supply.
Currently National Grid Electricity System Operator (‘NGESO’), the company responsible for the safe operation of the electricity system, manages the existing lack of stability by asking renewable generators, predominantly wind farms, to curtail their output and instead paying gas fired power stations to generate. This is to manage physical constraints of the network and also to ensure the electricity system has sufficient stability in the form of reactive power, inertia and short circuit level to ensure a stable reliable system.
The total cost of these actions exceeded £2bn in 2022 with the cost of managing inertia alone amounting to £104m. These costs feed directly into consumer bills.
Synchronous condensers such as the one being built at Cilfynydd provide the stability currently missing from a renewable dominated electricity system. They allow renewable generators to operate by providing the stability currently being provided by carbon emitting fossil fuel generation.