Type-tested devices

Integration – Harmonisation – Implementation

When you import your power-generation equipment into the United Kingdom, you must obtain all the information mentioned above. This proves to be much more difficult, because all the implementation areas listed here are now governed by Engineering Recommendations G99/2, and you will not receive permission for parallel grid connection for your equipment unless you comply with these ERs. The ER G99/2 are intended to cover all aspects of the connection process—from functional standards to on-site commissioning—so that customers, manufacturers, and generators are aware of the requirements that the local DNO (Distribution Network Operator) imposes before the power-generation installation is accepted for connection to the distribution network.

The guidelines contained in ER G99/2 are intended to facilitate the connection of power-generation module(s) while simultaneously ensuring the integrity of the distribution network in terms of safety and power-supply quality. This applies to all power-generation modules under Section 2, regardless of the type of electrical machine or equipment with which a primary energy source is converted into electrical energy.

Developers and suppliers of generation equipment

Developers and suppliers of generation equipment must be familiar with the new G99/2 regulations to ensure that their products meet these higher performance requirements. And this is where Applecoat Ltd can simplify the process for any importer from any country. We can carry out type-testing for your equipment and register this equipment with the relevant authority. In addition, we can establish the connection with any distribution network operator in the United Kingdom.

With our service package, we can also carry out on-site witness tests, which the DNOs may still request even after the full type-testing has been completed, as such follow-up inspections are permitted.

For type-tested interface protection, the protection settings are defined during manufacturing. The regulations define type-tested equipment as “a product that has been tested to ensure that the design meets the relevant requirements of G99/2.” All similar products are manufactured to the same high standards and therefore meet the same performance levels.

Non-type-tested interface-protection systems require additional tests and measurements to assure the regulator that the protection you are using is sufficiently robust.

If you intend to familiarise yourself with the G99/2 regulations, you must also consider all the following areas in which the British DNOs have shown increasing interest—these are shown below.

Frequency-response requirements

Generators must now control their active power output in response to changes in grid frequency. The frequency-response requirements are divided into two modes: Limited Frequency Sensitive Mode (LFSM) and Frequency Sensitive Mode (FSM).

The Limited Frequency Sensitive Mode requires generators to reduce active power (MW) when the frequency rises above 50.4 Hz and increase active power when the frequency falls below 49.5 Hz. By contrast, Frequency Sensitive Mode (FSM) imposes a greater requirement for larger generators and requires the installation of a fast-acting proportional frequency-control device that responds to frequency changes and can quickly increase or decrease active power by 10%.

Fault-ride-through requirements

Generators above 1 MW must now remain connected to the grid when significant voltage drops occur as a result of network faults. This is referred to as “fault ride-through” and helps prevent network blackouts by ensuring that a failure at one generation site does not cause additional sites to disconnect. The depth of voltage drop through which a generator must remain stable depends on the generator’s size, with the largest generators required to withstand a complete voltage loss for 140 ms.

Requirements for fast fault-current injection

Generators above 1 MW must also support the system during a fault by quickly injecting reactive current so that the grid voltage does not fall too low. This function helps to prevent the loss of additional consumers and generation sites during faults by ensuring that grid voltage remains as high as possible.

Voltage-control requirements

G99/2 requires generators to have a voltage-control system capable of injecting or absorbing reactive power to regulate voltage. The DNO instructs the generator to operate in one of three modes: voltage control, reactive-power control, or power-factor control.

Reactive-power capability

The reactive-power requirements for generators have also been tightened. For power-generation modules between 1 MW and 10 MW, they must allow continuous operation between a power factor of 0.95 leading and 0.95 lagging at the connection point when operating at registered capacity.

Generators larger than this have specific reactive-power capability windows within which they must be able to operate (at all points).

Applecoat Ltd can obtain type-testing approval and provide advice on any import of power-generation equipment you bring into the United Kingdom.

If you require additional training modules and general information on G99/2 or G98/1-2, visit our online training portal, where you can access the information in English, German, French, Spanish, or Italian.