Heathrow Closure

mapj1 said:

remarkable in an organization that size

That's usually part of the "too big to fail" problem, until the holes in the Swiss Cheese align, not forgetting that those holes can start at the edges of the cheese slices near the top layer.

It's hard to see these hairy big failures and how other systemic aspects will undermine all the planning. It's been seen in many 'big system failures'.

Some oldie but goody reading.

1. Reason, J.: ‘Human Error’ (Cambridge Univ. Pr., 1990

2. Rasmussen, J., Pejtersen, A.M., Goodstein, L.P.: ‘Cognitive systems engineering’ (J. Wiley & Sons, 1994)

If it were up to me, I wouldn't even allow microprocessor relays without an electromechanical relay backup for the critical feeders. Putting all your trust in a microprocessor that can be programmed to burn itself up at a moments notice (or predefined future time) seems foolhardy to me - maybe I'm just paranoid.  Then again, we're constantly being told to expect cyber attacks from state actors, so why the disparity?

Will we ever find out the real causes?

Well maybe, though there seems to be enough high level interest to trigger an inquiry.

It does seem pointless to have multiple in-feeds at HV if there is no  mechanism for performing the change-over faster than the hold-up time of the emergency power.
As above it sounds like the suitably qualified folk to make the technical decisions and pull the right  levers, perhaps even literally,  were not available - which is remarkable in an organization that size, even if the battle plan for such an event had to involve losing supplies to non-essential areas.

After there are plenty of other places with dual HV feeds and HV rings with zone isolation switching and so on, - consider for example that  most large hospital campuses manage this sort of thing as a matter of routine and even manage to rehearse on a semi-regular basis as well as during planned maintenance. It ought not to be that hard to have someone who understands the systems available at short notice.

Mike.

Heathrow had enough power to avoid shutdown, says National Grid | The Independent

National Grid CEO John Pettigrew told the Financial Times: “There was no lack of capacity from the substations. Each substation individually can provide enough power to Heathrow.”

Heathrow’s management acknowledged on Friday that: "the site was served by two other substations", but claimed that, "in order for these to be used, the power supply to all terminals needed to be re-engineered."

A Heathrow spokesperson said: "It would not have been possible for Heathrow to operate uninterrupted. Hundreds of critical systems across the airport were required to be safely powered down and then safely and systematically rebooted."

It sounds like some manual reconfiguration of the in-feeds was required to reroute the supply. I find it hard to believe that automatic transfer switches were not installed for the HV distribution system. Even if manual switching was required, I'm amazed that it would have taken longer that the UPS autonomy time from critical systems.

Lots of questions. Will we ever find out the real causes?

Given the various shambolic official responses about “needing to reconfigure” their power, it looks like all of the 3 internal 33kV substations at Heathrow (ie. within their site) had power on the Longford leg, but had lost power on the North Hyde feed. Probably no duty HV engineer to drive round and switch the RMUs. Really appalling. 

Some reports have been saying that Heathrow has the demand of a fair sized city ... suddenly removing that size load from the National Grid must have been quite a challenge - presumably one that the grid controllers coped with though.

     - Andy.

I know some people here in Florida who plan to visit the UK in a few months.

Even before this event, I have been strongly advising them to cancel their trip.

Peter Brooks

Palm Bay FL.

Note sure about Black Swans but I can imagine there are some people wearing brown trousers

Hello Andy:

My take on the situation is that here we have a single point failure and a black swan event!

Where is the wonderful AL system that should have projected that this event would happen at this specific date/time?

Peter Brooks

Palm Bay Florida 

The North Hyde GSP network is made up of 66kV, 22kV, 11kV, 6.6kV, and LV circuits. It is an urban network located in west London where the land use is a mix of residential, commercial, and industrial with no agricultural land.




It is worth noting that there are two sites where the SSEN Distribution network connects to Heathrow Airport within the GSP area. In total the GSP serves approximately 64,000 customers with the breakdown for each substation shown below 

Substation  Type No. Customers Served 2023/24 Pk recorded MVA

North Hyde (B) Grid Supply Point 63,577 169.44
North Hyde (D) Bulk Supply Point 5,894   28.15

North Hyde (E) Primary Substation 16,081 43.37
Bath Rd EastPrimary Substation  3,049   7.55

Hayes Primary Substation 17,300  31.44
Springfield Rd Primary Substation 8,476 12.81

The Green Primary Substation 4,279 8.50
Vicarage Farm Rd Primary Substation 17,484  24.33