12 March 2018
By email: Online forum fyi.org.nz
Official Information request – NZ power grid protection from coronal mass ejection
Dear B Pinkney
Thank you for your request under the Official Information Act 1982 requesting details on
what planning and research has been undertaken or commissioned by Transpower relating to
grid-related damage from solar activity and grid hardening. We received this request on
Monday 12 February 2018.
This response was prepared by one of our Senior Principal Engineers.
Background – Ground Induced Currents
Ground induced currents (GIC) can be due to many reasons, both manmade and naturally
occurring. Over the last 50 years Transpower has developed an increasilgly sophisticated
dense network of ground current recorders that monitor current flows in the neutrals of
numerous transformers across the country. These neutral currents are recorded, analysed and
stored to help us manage the HVDC and as such we have built up a knowledge base
including direct measurements and experience of GIC.
Naturally occurring GIC are mostly associated with the interactions between the solar winds
charged particles and the earth’s magnetic field, and are visible during aruras. When
extremely large and violent solar winds are produced, Coronal Mass Ejections (CME) (GIC
large enough to cause damage to power grids) are possible. This is rare, with the most recent
event causing wide spread damage and blacking out the province of Quebec in 1989.
Transpower’s involvement with research and preparedness for CRM GIC
We receive regular space weather forecasts from the National Oceianic and Atmospheric
Administration (NOAA) to our control centres and have operational procedures to manage
the effects of GICs ranging from reconfiguration of the network to disconnection and
isolation until the GICs reduce below damaging levels.
Transpower utilises the satelite based Global Positioning System (GPS) to provide a
nationwide universal time synchonisying service. Regarding your question on our reliance on
GPS for time syncing in our communications and protection systems, a study has been
undertaken to quantify the impact should the GPS constellation be lost for any reason. The
impact of this is expected to be minor with random inconvenient disruptions. The adoption
of the 1588 protocol for all switches, routers, and master controllers as part of their normal
lifecycle management will completely address the issue by the end of 2025.
Both NASA’s Goddard Space Centre and the British Geological and British Antarctic Survey
programmes are building computer models of how solar flares, the earth’s magnetic field and
geology interact so that predictions of the location and magnitude of GIC and their impacts
on electricity grids can be made.
Due to our extensive Neutral Current Transducer DC (NCTD) measurement array, its historical
dataset, and our power system model, Transpower is involved in a Ministry of Business
Innovation & Employment funded international research project to help construct a New
Zealand geophysical model. This work will enable us to:
•
Predict the likely impact of severe/extreme geomagnetic storms on the New Zealand
grid with higher accuracy;
•
Inform our real time GIC security policy;
•
Test our existing GIC mitigation protocols against historic and predicted GIC to identify
improvements; and
•
Procure equipment that can accommodate severe GIC or design suitable mitigations
to manage such an event.
The project is expected to finish in 2018 with results being available from 2019.
As part of the work done to date in understanding and validating the geophysical GIC, we
have also assisted in developing an aurora-warning system for the lower South Island. This
was released to the public as part of the MBIE project during the New Zealand Antarctic
Science Conference held in Dunedin in 2017
Please do not hesitate to contact me if you have any further questions or comments in
relation to this information.
Transpower takes this opportunity to inform you of your right to a review by the
Ombudsmen of Transpower’s decision regarding the above information, under section 28 of
the Official information Act.
Yours sincerely
Hanna Davies
Governance Counsel
Transpower New Zealand Limited
