Revised Engineering Recommendation ER G83/2

After several months of consultations with OFGEM, DNOs and stakeholders from the disitributed generation industry (of which I was a part), the Energy Networks Association published the latest update of Engineering Recommendation G83/2, replacing G83/1-1.

The ENA has also published a revised version 19 of the Grid Code, which gives installers and manufacturers until 1st March 2014 to implement the necessary changes.

Key Changes

There have been a number of substantial changes to the Recommendation, which for the most part reflect the increasing penetration of renewable energy into the Grid. Key changes are:

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• Application forms for multiple site projects have been simplified (hooray!)
• There is a proper definition of multiple sites, which does expand its scope a bit
• Inverter settings will change to become similar to those in G59/2-1

The last point brings the document in line with the requirements for larger projects, and is to be widely welcomed as it brings greater stability to the public supply network. It's not quite the dynamic approach taken by Germany's current VDE-AR-N 4105 and others, but it is definitiely an improvement.

The changes to multiple-site projects was the subject of considerable discussion in the Distributed Generation Working Group run by ENA for the purpose. The intention is to protect DNOs fairly against incremental changes to their network caused by rapid uptake of domestic PV systems. After all, 25 typical domestic PV systems - just one street - can create a 100kW generator on the network overnight without the DNO finding out about it until 28 days after the event. Yet doing the same as a single commercial project would require advance notice to allow for grid studies, reinforcement work etc. The challenge has been how to give DNOs fair notice without unduly interfering with customers getting a system installed.

What is ER G83?

Officially titled "Recommendations for the Connection of Type Tested Small-Scale Embedded Generators (Up to 16A per phase) in Parallel with Low Voltage Distribution Systems", Engineering Recommendation G83 is enshrined in the Grid Code for the UK. This Code is a set of requirements coordinating the efforts of the various Distribution Network Operators around the UK - the organistations that own the national electrical cabling system. G83 itself sets out the rules for connecting most domestic renewable energy systems to the public grid. It sets out the required installation and product standards, protection arrangements and the process by which potential clients can, via their consultants, apply for their system to be connected.

A core part of G83 is the provision of protection against deviations in voltage and frequency, and providing systems to enhance the stability of the national power networks. A common misconception is that this is protecting the generator; actually it is the network that is being protected, and this is why network operators insist on implementing it before they let a system be connected.

To illustrate this, many clients ask me "Why can't my system keep working when the mains fails?" The answer is quite simple: If the mains fails, it's because there's a fault or its been switched off, and either way there will be someone coming along to work on it soon. If it continued to generate, it would feed power into the fault, which would of course be rather dangerous for the linesman fixing the supply!