Forgotten substation design

UGL chief engineer power, John Giles discusses the less ‘exciting’ aspects of substation design.

You wouldn’t expect a substation design presentation to be slightly tongue-in-cheek, but according to UGL chief engineer power, John Giles, that will be his main aim at Smart Substations 2011 in April.

“The general thrust of my talk is probably a bit tongue-in-cheek because, really, what I’m saying is, because a lot of people focus on the electronic smarts, in other words the 61850, they do that at the expense of being smart on all the old-fashioned aspects of substations,” Mr Giles explained to Energy Source & Distribution.

“Although the (event) is called Smart Substation Design, it’s not actually specifically talking about smart electronic design,” he said.

“There are paradigm shifts occurring in other aspects of substation design. I look after a team of designers for substations here and I find that they all get excited about the electronics and forget about the basic stuff. And the basic stuff does need to have some ‘smart’ or more smart aspects added to it.”

One of Mr Giles key concerns is electrical losses, an issue that has gained attention in the wider media.

“There’s been a bit in the press recently about electricity losses, saying we generate 100 units of electric and seven units go in the generation loss. There’s another seven units that go into transmission loss and there’s another seven-10 that go into distribution losses. And you add that up and that’s 21 per cent. In other words, 20 per cent of your electricity does nothing for the customer,” he said.

“There’s lots of things we can be much smarter about when we design substations, such as transformers and so forth, to reduce those losses.”

Loss of power in transformers is a major area of concern for Mr Giles.

“There was a little article by Martin Thomas recently that said that these losses equate to $4.5 billion a year, which is a big number. And I’m thinking we should be re-investing some of that loss number back into making our substations a bit better.”

Some of the major projects he will discuss at the event are four 500 kV substations UGl recently built in New South Wales.

“Basically it has to do with being an outer ring around Sydney, which starts at the Hunter Valley and goes all the way down towards Goulburn and its about a $200 million job for us just in the substations. A lot of the aspects we had to be quite smart about because some of the subs are in Sydney catchment authority areas runoffs, which is what we are going to talk about. Drainage runoff control is rather important. Flood studies, which is quite topical considering Queensland, which nobody bothers to do and they build all these infrastructure below the water level which disappears. That’s the sort of gist of what I want to talk about.”

One of UGL’s projects is the Bannaby substation, which requires building a one kilometre road to get into it.

“From the back of the sub to the front of the sub is 900 m, so it gives you an idea of how big this sub is. It’s huge,” Mr Giles said.

The Beaconsfield West project will be a 330 kV gas-insulated switchgear substation.

“That is reasonably unique because its one of the more modern substations and it’s got what’s called gas-insulated lines in it… instead of having cables, (it has) busbars with a gas insulator in it and outer sheet. It’s very high power, you can put lots of cable connection very close to each other, which is what you can’t do with open busbars.”

With a confined location squeezed next to a heritage canal, the panel beaters next door had to be bought in order for Beaconsfield West to expand.

“All the things in that substation, in what I call smarts, are all to do with non-electronic things. The footings, what we’re going to do with the canal, noise problems for the next-door neighbours, fire problems… all of those sorts of things,” he said.

“In Sydney it’s going gas-insulated. We’re building one for TransGrid. We’ve got a tender in for two more and I think four or five for (Ausgrid). Gas-insulated switchgear is definitley the way things are going. But they bring with them lots of other problems because once you compact things down you get a lot more problems with magnetic fields. That’s a very sore point with a lot of supply authorities.”

Mr Giles is involved in writing a new standard for substations, AS2067.

“The old standard was (from) 1984 and basically was a mishmash. The new one basically, which is only a couple of years old now, beginning of 2009, has got new requirements for all of these other aspects of fire and building safety and a whole range of extra things, which people are just coming to grips with at the moment which is why I think we need to be smart about using those new rules, basically,” he said.

Mr Giles said the standards have become increasingly sophisticated in the past few years, with Australian standard taken up by the IEC to modify their own standards.

“So we’re reasonably in the forefront in that area. And similarly not in the task but I’ve been involved in transmission line standard, this is the first time there’s been one in Australia. So that’s also interesting,” he said.

Fire and noise are becoming increasingly significant issues for the community, requiring creative solutions for substation design.

“You know, people don’t like having a ‘flammy’ great substation next to them with a big, noisy transformer. Because all of our infrastructure is at the falling apart stage, most of it is getting around the 50-years-old age, that’s sort of the design life of this equipment,” he said.

“So it’s all falling apart and add to that the urban consolidation problems and we’ve got to have a bigger and better renewal program in Sydney, presumably in the other states at the same time, of all their electricity infrastructure. And you can’t get routes to put your cables up streets, you can’t find blocks of lands to put your substations, so we need to be smarter about how we design them and that’s what I’m going to talk about in the architectural (area),” Mr Giles said.

“You know, we are going to build substations which look like a block of units. (The recently built Sydney substation) Kogarah has been built to look like an old theatre. We’re need to be smarter about how we present this stuff to the community.”

Mr Giles said the industry will soon face a significant skills shortage.

“We have a lot of baby boomers, which I’m one. Then we have a big gap in skills, then we have Xs and Ys generations coming up, but we’ve got probably another five years when all of us baby boomers are going to retire and there’s a gap of leaders before the next generation. Those guys just don’t exist.

“I’ve noticed that the power school in all the universities have disappeared and there was no power training for substation people. That’s had a huge effect, cause what we have to do now is (get) raw graduates and try to train them. And the graduate this day only wants to stay here five years and (then) wants to got off and design medical instruments… so there’s no career progression.”

Mr Giles has witnessed incredible change in substation design in his 40 years in the industry.

“From my point of view when I first started, I used to design everything. I did the civil, structural, earth works, the lot. But now I’m not allowed to do that any more. I’m an electrical engineer so I’m only allowed to the electrical. Legall,y I can’t design and sign my name to structurual things for instance. In that case the designs have become a lot more sophisticated for structures and so forth. Everything’s been skinned down to be more economic.

“The way we do things has changed significantly. We have all these environmental requirements, aboriginal heritage, noise, visual amenity, etc. And we had more space obviously to put substations.”


 

Electricity losses – do they matter?

Extract by Martin Thomas, AM FTSE HonFIEAust FAIE

Nationally, according to published data, some 7 per cent of electricity generated is consumed in internal losses and auxiliaries consumption at the power station, with the balance being net ‘electricity sent out’. Losses following in the national transmission system are also substantial, typically another 7 per cent through the step-up transformers, switching stations and the nearly 40,000 km of high-voltage overhead and underground transmission lines and cables (220 kV up to 500 kV) that interconnect and span Australia’s states. A further 7–9 per cent or more, depending on numerous local factors, is lost in lower voltage more scattered customer distribution systems, typically from 132 kV down to 240 V single phase at the average domestic customer’s meter.

Conventionally, the power from large coal, gas fired or hydro generators is supplied at around 25 kV and immediately stepped up to a higher voltage through the adjacent power station transformers for direct feed into the transmission system.

This minimises losses at the first step of the customer pathway although at this stage values are still low, especially for base load power. This is not the case for many renewables which, through low source intensity, are generally distributed widely and remotely in much smaller generation units.

Wind farms typify this paradigm which introduces a further loss factor, which my colleague John Sligar in a recent a submission to the Prime Minister’s Task Group on Energy Efficiency described as an ‘assembly network’. This submission pointed out that with low wind generator terminal voltages of say 600 V, and lower from solar panels, the ‘assembly network’ is far more widespread, comprising inverters, long medium voltage feeders and numerous relatively small transformers before grid voltage is attained. Average losses in the assembly network, depending on topography and line lengths, can be significant with estimates of 5 per cent – 10 per cent or more being quoted. But, given the ‘squared’ loss multiplier for current flow, it follows that losses at system peaks are firstly much higher than the average and, by definition, occur when electricity value is at its highest.

The world of losses and quantification of their value in terms of revenue foregone is indeed complex.