Electrical Grid Connected Generation & DNO’s

20/05/2009 by David Slade.

Grid Connected Generation

Terminology to Start

• Developer

– You!

• Distribution Network Owner/Operator (DNO)

– Owns, maintains, develops and operates the physical network
– SP Manweb, United Utilities in the North West
– Not the slightest bit interested in selling or buying energy from you

• Electricity Supplier

– Party to contract with to buy & sell energy
– Npower, PowerGen, Scottish Power, British Gas, etc…
– Not the slightest bit interested in the physical connection

• Ofgem

– Electricity and Gas Market regulator
– Also administers the ROC process if your technology is eligible

Just Some of the Legal Issues

• If grid connected, then it is a legal requirement to have permission to connect & operate any form of generation

– Needs to have a DNO connection agreement
– Needs to have correct electrical protection
– Needs to have correct earthing
– Needs to have an export meter (if exporting)
– Needs to have a supplier contract (if exporting)

• D-code : Distribution Code for UK Distribution Networks

• G-code : Grid Code for UK Transmission Networks

• Electricity at Work Regulations

Engineering Recommendations

• Technical connection requirements are detailed in the Engineering Recommendations

– DNOs view these as “Rules” rather than just “Recommendations”

• G83: Less than 6kW (16A/phase)

– No connection agreement required but must notify DNO once on

• G59: Less than 5MW and less than 20kV connection

– Must have a connection agreement

• G75: Anything else up to 50MW or transmission connected

– Must have a connection agreement

DNO Responsibilities

• Statutory obligations under the terms of their licence

– Secure operation and development of the network
– Safe & reliable operation of the network
– Ensure fair and equal access to the network
– Least cost options for connection
– Lifetime of network not just your connection

• Must respond to a connection application within 90 days. Remember, they’re not out to get you, but they have responsibilities too!

 Electrical Connection Issues

• Technical issues to be considered during connection study/investigation

– Thermal limits
– Voltage limits & step change
– Reverse power-flows through transformers
– Short-circuit rating of switchgear
– Protection arrangements & co-ordination
– Harmonics & Power Quality
– Transient stability (usually only for larger generators)

• Energy Metering

• There will be the need to provide a reasonable level of data on the generator and the site connections

• The connection and protection will need to be witnessed and approved by the DNO in order to complete the connection process

 Network Capacity Issues

• The Distribution Network has real limits

• Due to load growth and the drive towards maximising use of existing assets, available headroom is often quite limited

– Cable ratings reached during peak load
– Voltage drop/rise reached
– Circuit breaker short-circuit limits reached

• The Capacity Race

– It is not just fiction it is unfortunately real in some locations
– First-come, first-served & Interactive Applications
– There are some solutions but most do add cost and complexity

 Rule of Thumb Connection Capacities

< 6kW 240V
< 1MW 415V (3-phase)
< 1-10MW 11kV
< 30MW 33kV
< 50MW 66kV/132kV
> 50MW 132kV upwards & National Grid interfaces…

As with any project, the bigger the project, it is important that you have the right level of advice or expertise to de-risk the project.

 So, what do I do to get connected?

• Contact your friendly neighbourhood consultant ☺

But seriously:

• Start with a rough idea of what you want to do

– Check that your site can fit it and you can afford it
– Check that all other regulatory issues are okay

• Have an informal “chat” about connection possibilities with DNO generator connections or knowledgeable person

– Check that your initial idea still sounds sensible

 When contacting the DNO

• Contact DNO – generation connections (NOT Demand)

– The connection process will be more likely to be successful with good communication between the developer and the local DNO

• Determine your connection route: G83, G59 or G75
– This may have costs associated with it

• Be prepared for a process not just rubber stamping

– Planning & Information phase
– Detailed Design phase
– Installation phase
– Testing & Commissioning phase

 Working with the DNO

• Seek an early meeting to discuss your project

– Outline the scheme
– Discuss the DNO’s process for connections
– Request an indicative connection design and budgetary cost estimate with a split between contestable & non-contestable works

• Review your project

– Submit the formal connection application
– Remember to accept the connection offer!

• Submission of data to DNO

– Make sure that this is appropriate and timely to avoid delays

• Testing and Commissioning

– Plan in advance to avoid delays as staff will usually be quite busy

 Connection Charges

• Application Fees

– These vary between DNO and size and voltage level of project
– Complex projects may involve additional fees

• Connection Assets

– Developer will be expected to pay full costs for all sole-use assets

• Generation Use of System Charges

– Site dependent & in lieu of network reinforcement costs
– Each DNO has own policy in-line with Ofgem guidance

Competition in Connections

• Developer as two options:

– Get the DNO to do all works necessary for the connection
– 3rd party to provide all contestable works which DNO then adopts

• Contestable Works

– Supply & installation of any new assets up to the point of connection to the existing network. Adoption agreement required.

• Non-Contestable Works

– Any studies, reinforcement or installation on existing network
– Design & specification of any new assets, consents & way-leaves

• Note: The DNO will not get involved in any “on-site” works

 Finally, just when you thought it was too easy

Other non-electrical issues still need to be resolved

– Planning Permission?
– EIA, Emissions?
– Health & Safety?
– Commercial?
– Installation & transport?
– CDM?

Posted in G75, Connection Charges, Contestable Works, Non-Contestable Works, G59, G83, Energy, metering, Ofgem, NDO's | Print | No Comments »