``The Changes” From “Vector Shift to ROCOF``

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These changes are going to be the biggest change since G59 was first implemented many Years ago, please read the following information and see if you agree, if you do agree with me, then you need to get booked onto one of our Test Engineer training courses.

The back ground to these changes are as follows.
•    Emerging and increasing risk of high RoCoF frequency excursion leading to RoCoF protection trips on Distributed Generation.
•    Phase 1 dealt with DG>5MW
•    Significant difficulty in completing this programme on about [200] sites.
•    There is a strong business case for phase 2 for all remaining DG – approximately 40 000 sites.
•    A different approach using dedicated and funded resource is proposed for Phase 2 –but will require DNO and NG expertise to initiate and manage.

Emerging Vector Shift issues.
•    Currently under detailed investigation
•    Langage incident (May 2016) has shown there could be a real issue with VS protection fitted to DG
•    Hitherto VS has been as an acceptable alternative to RoCoF
•    Worst case is that VS protection will trip inappropriately over a wide area for transmission faults – possibly exceeding the 1800MW maximum infeed loss.
•    New settings might be possible to avoid this risk, but would probably need applying on a regional or national basis
•    Final recommendations for settings or for replacement will be factored into the overall RoCoF update programme.

The benefit of making these changes.
•    Savings of > £50m per year will be made by completing the RoCoF settings programme.
•    Savings are the avoided Balancing Service costs of managing the total system to a RoCof    limit of 0.125Hzs
•    managing vector shift trip risks
•    Balancing Service costs flow through National Grid’s Balancing Service Incentive
•    Savings go to consumers as targets take account of known changes with a 12 month or greater lead time

Rectification Costs
•    DNOs collaborated in the summer of 2016 to build a model of implementation costs
•    There are approximately 40 000 generation sites of less than 5MW, excluding domestic installations.
•    From research undertaken by the WG, the inverters used in domestic generation are not sensitive to RoCoF.  Their insensitivity to VS is being established.
•    Domestic inverters are not included in the proposals as it is not believed there is any issue with them.

Rectification Costs
•    Although numbers of sites are known reasonably accurately, the incidence of RoCoF protection or VS is not known, nor whether fitted to synch or asynch generation.
•    A best estimate has been made with high and low sensitivities to allow for errors in estimates etc.
•    To reset all relays on generation <5MW

•    Best Estimate             RoCoF Only      RoCoF and VS
•    Best Estimate                 £16.1M               £46.8M
•    Low sensitivity               £9.3M                £22.1M
•    High Sensitivity             £46.7M              £229.5M

•    The high sensitivities assume network modifications to minimise risk for synchronous generation; it is also assumed that these costs would be recharged directly to generators – so it is likely that they will be significantly overstated as generators will seek lower cost mitigations within their own control

Suggested Implementation
•    The programme is substantial and needs to benefit from economies of scale
•    Dedicated resources can be used to Research, contact and doorstep generators
•    Perform screening and detailed risk assessments for synchronous sites
•    Change relay settings
•    Project manage any physical rectification actions for individual synchronous sites
•    Update DNO records

Next stage of Implementation
•    The Working Group will:
•    Determine the necessary future proof RoCoF and VS settings
•    Write up the business case for the changes
•    Provide draft legal text for D Code changes.
•    Consult on the proposals – date TBA
•    Write a detailed technical specification for the work to be undertaken
•    Actions outside the WG
•    Create an implementation project under ENFG governance
•    Determine detail of TNUoS approach and suggest licence modifications to Ofgem
•    Determine the contracting and commercial strategy for contracting in the necessary resources
•    Develop the appropriate delivery incentives and assurance
•    Agree a Project Management approach and timescale for completion

The next move
•    The Working Group will:
•    Determine the necessary future proof RoCoF and VS settings
•    Write up the business case for the changes
•    Provide draft legal text for D Code changes.
•    Consult on the proposals – date TBA
•    Write a detailed technical specification for the work to be undertaken
•    Actions outside the Working Group
•    Create an implementation project under ENFG governance
•    Determine detail of TNUoS approach and suggest licence modifications to Ofgem
•    Determine the contracting and commercial strategy for contracting in the necessary resources
•    Develop the appropriate delivery incentives and assurance
•    Agree a Project Management approach and timescale for completion

The truth is, the DNOs are fed up with Vector Shift tripping far too easily, and its giving them a massively unstable system, when they agree to change the settings to ROCOF, it will mean a large amount of work for both companies and test engineers.

So why not get ahead of the curve, and get your systems changed to ROCOF, or if you are looking for a massive increase in work load, then get in touch and book on one of our Test Engineer Training courses.

We are already getting a lot of calls from customers asking for either periodic tests on their panels where we can undertake the changes at the same time, or just straight forward changes from vector shift to ROCOF.
So please get in touch and see what we can offer you.

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