Stability services

The series of Network Option Assessment (NOA) Pathfinder procurements launched by National Grid ESO is in response to the increasing amounts of energy generated from renewable and low carbon sources leading to a greater need for stability services on the network, all to ensure a safe and reliable electricity grid.

Driven by the UK’s net zero targets for 2050 and the goals for NGET to operate at Zero-Carbon by 2035, the increased penetration of renewables in the generation mix is resulting in a lower provision of short circuit level support and inertia as the old thermal generation retires.

The need for stability products varies across the country, and so National Grid have embarked on a series of regional procurement exercises, to allow the market to provide solutions for this requirement. This also includes the need for voltage and frequency support.


National Grid ESO have varying requirements for stability services which they issue tenders for and these are dependent on the network characteristics of the substation and surrounding region of need. Conrad Energy is participating in these tenders and developing projects to meet these requirements.

Conrad Energy are flexible in which technology can be utilised and will select the most suitable to meet National Grid requirements. Further details on the various technology options that may be proposed and utilised are set out below.

Synchronous condenser

A synchronous condenser (sometimes called a synchronous capacitor or synchronous compensator) is a DC-excited synchronous motor, whose shaft is not connected to anything but spins freely. The plant can be contained within a purpose-built acoustic enclosure to ensure that there are no adverse noise impacts on the surrounding area.

Ancillary infrastructure typically includes external cooling fans, enclosed diesel generator and small fuel tank, transformers, flywheel, cabling and containerised control equipment.

Its primary purpose is to adjust conditions on the transmission grid, including to either dynamically absorb or supply reactive power as needed to adjust the grid’s voltage, or to improve power factor. After the generator is synchronised with the network it behaves like a synchronous motor with no load, providing short-circuit power to the transmission network. The Synchronous Condenser also provides the necessary inertia for the power grid by means of its rotating mass and during emergencies or contingencies the synchronous condenser can provide a significantly higher rating for a short time.

Shunt reactor

A shunt reactor is an absorber or compensator of reactive power, which is used to increase the energy efficiency of the electricity system. It is a most compact device commonly used for reactive power compensation in long high-voltage transmission lines and cable systems.

It involves the installation of a large transformer with only one winding per phase and ancillary equipment to connect to the grid.

The increasing use of renewable energy sources is bringing changes to traditional generation dynamics and is placing new demands on the transmission network. The dynamic and time varying effects associated with renewable sources play a more pronounced role in networks, this helps to facilitate.

What is Short Circuit Level?

Short Circuit Level is the amount of current that flows on the system during a fault. These faults can be caused by a lightning strike, weather conditions or equipment failure. During the fault, the system can see a direct connection to the earth and current flows from all sources into it. SCL is vital during such a fault as it helps us to maintain system voltage preventing further disconnections or regional black-outs.

What is inertia?

Inertia is incredibly important to maintain a stable grid network. It irons out some of the friction caused in the network’s voltage and frequency and keeps the electrical supply stable and secure. An example of this is similar to a shock absorber in a car’s suspension, which dampen the effect of a sudden bump and keep the car stable and moving forwards.

Recent grid stability projects

Tonteg synchronous condenser project

Welcome to the information page for our proposed Tonteg synchronous condenser project. Conrad Energy is proposing to develop a synchronous condenser facility with associated infrastructure, access and landscaping on land…

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