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Old grid, new tricks: Wind power at “bleeding edge” of energy revolution

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If the Australian wind industry seems a bit defensive at times, it is with good reason. For starters, it was effectively brought to a stand-still, as the proudly anti-wind Abbott government put the RET in limbo and a veil of uncertainty over the entire clean energy industry. Then there were the multiple Senate inquiries, the health claims, the state government level planning setbacks, and the seemingly random appointment of a national wind farm commissioner.

Now, with the RET locked in, the wind farm commissioner making sensible noises, and investment starting to take off again, a new hurdle faces the wind industry: how to get all that prospective wind energy capacity onto the grid.

solarandwind

Indeed, grid integration was one of the major topics at the 2016 Wind Industry Forum in Melbourne on Thursday – the third gathering of the annual event and, according to organisers, by far its most well attended, reflecting the industry’s vastly improved prospects compared to 2015.

The Forum gathers together wind industry players as well as regulators and network operators to map the way forward for wind farm development, as governments meet emissions targets and Australia’s coal and gas-based energy system is gradually displaced.

But it is this last part that is currently causing headaches for both the energy market operator and the wind industry.

How do we integrate thousands of megawatts of wind energy – AEMO in 2015 forecast 6,700MW of additional large-scale (renewable) generation would be added to the NEM by 2020 – into a grid and market designed around centralised “synchronous” power plants?

As far as the wind industry is concerned, this is problem both real and imagined. The real part of the problem – the need for updated market and trading regulations and for upgraded technology and infrastructure – is perfectly doable. The imagined part, however – the public perception, driven by media hype, that wind energy will send the grid into meltdown – will be the hard nut to crack.

In South Australia, for example, the state where the wind industry has had its greatest success to date – wind and solar together have on occasion accounted for as much as two-third of the state’s daytime demand – and where the government is introducing more and more ambitious climate targets, wind energy has been variously blamed for rolling blackouts, major grid outages and rising electricity prices. Unfairly – it turns out.

As Pacific Hydro’s manager of electrical engineering, Kate Summers, put it at the Forum “challenges in frequency control are related to high penetration of wind in SA… according to everybody’s impression.”

But as Summers went on to say – and this has been explained in detail here – the rolling blackouts that hit SA consumers in early November last year happened not due to wind farms, but because “non-scheduled generators” suddenly switched on, chasing frequency regulation prices that went through the roof, and sent the grid “barrelling through” its 50Hz limit.

“When the frequency hit 50.5 Hz, the wind (output) was very stable, and was not contributing to frequency woes,” Summers said.

Meanwhile, as the NEM experiences more and more minimum demand periods, wind farm outputs, with their ability to respond rapidly to demand peaks and troughs, are increasingly being constrained – as was the case with the Oakland Hill wind farm during that November incident, which Summers says was oscillated off for the entire weekend.

“This is lost wind energy,” she told the Forum. “We have a right to be grumpy.”

But if the wind industry has a right to be grumpy, parties like the Australian Energy Market Operator (AEMO) have a right to be cautious about managing large additions of new capacity and controlling grid frequency.

As AEMO principle analyst Rob Jackson told the Forum, this scenario is playing out to some degree or other all around the world.

“South Australia has very, very high penetration of renewables,” he said, which puts Australia on par with markets like Hawaii and Texas – the latter where wind farms recently provided between 20 and 45 per cent of the state’s electricity over the course of one day.

“This (kind of transformation) needs new grid standards, new operating rules, new markets, infrastructure, new technologies,” Jackson said. “We are at the bleeding edge.”

Andrew Jones, energy services manager at LR Senergy, agrees it’s a time of flux.

“The power system is like a large collection of wheels… If something goes wrong, put simply, you either need to pedal faster or put the breaks on at short notice,” he told the Forum.

Jones explained that as large, centralised fossil fuel power plants left the NEM, there was a reduction in “inertia”, and reduction in inertia translates into increasing need for fast frequency response.

“Wind, solar, storage can all provide this,” he said, noting that at a potential cost of around $85/MWh in South Australia, wind solar and batteries could ramp up fast, unlike a synchronous plant, which is comparatively slow to respond.

In this context, he said, it is “hard to see why these technologies would not enter the market once the economic opportunity arises, provided market design is robust and stable.”

When these particular stars will actually align, though, is the big question. Meanwhile Jones says to expect this period in the interim, where we still have large single units in the system, to be one of the toughest for the wind industry.

“The NEM has a history of reactive changes,” he told the conference. “High penetration renewables needs to be considered now – or, dare I say, 10 years ago.”snowtownII20080505_36pm

To Summers, there are a nummber of things that need fixing before the electricity market works like it should, particularly now that large-scale renewables are hitting their stride.

“I don’t believe at this point in time that we have efficient market systems to serve the community and the renewable energy industry,” she told the Forum.

“The fundamental problem is we insist the market drive the power system. Meanwhile, the power system has to operate in accordance with the laws of physics.”

“We need to scrutinise the provision of (frequency control and) ancillary services (FCAS)… What do we get? What do we pay for?

“The market is sending out oscillatory signals. A lot needs to be done to fix what’s going wrong here.”

For Nicola Falcon, AEMO’s group manager of planning, a main focus going forward should be on where this 6,700MW of new renewable energy capacity is built.

She says that, according to AEMO’s reckoning, minimal grid upgrades would be needed to accommodate this amount of new capacity, provided it was distributed strategically.

“That’s the challenge,” Falcon told the Forum. “The problem is if there is an interest in one area – such as there is in north-west Victoria right now – high wind output could start seeing constraint, which could see the system become weaker” and the short circuit ratio increase.

“We can only go ahead and build more capacity if it augments the market,” she said. “Could we displace coal? Coal is so cheap it is very hard to stack up the market benefits.

“Without certainty in policy, it is very hard… We need to add capacity without building out more transmission lines.”

One answer to this problem, however, could be in the development of renewable energy hubs – an approach that TransGrid’s Mal Coble is investigating along with the NSW government and ARENA in the New England region of the state.

“Transgrid is acutely aware of what’s happening in the changing energy landscape,” Coble said, by way of opening statement at the Forum on Thursday. “We think a Renewable Energy Hub could successfully bring more than 700MW in additional connections.

“It’s essentially a common connection point for multiple generators – a more efficient way of connecting individual (renewable energy) projects in an area.”  

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  • Andrew Woodroffe

    Sufficient spinning inertia?

    Has anyone looked at running old, existing coal power stations just for spinning inertia. That is, still connected but NOT generating as we are NOT talking about spinning reserve, here. What we are after is the inertia of spinning equipment which has value for maintaining system frequency the instant after an event where the inertia has the greatest impact and switchgear the least.

    All the steam and coal side works would be closed down and scrapped. But the all the electrical works kept and maintained.

    A tiny amount of electricity would be required to overcome bearing drag but that would be it for the service of spinning inertia.

    • Cooma Doug

      The grid today runs spinning reserve generators that switch quickly to generate when frequency excursions go beyond the 49.8 hz. There are many hydro units used for this and this also enables control of voltage on the system by variations of these machines exitation whilst spinning synchronised.
      In fact voltage control will be the most critical issue in the future. It too will become easier as the generation centres disappear into the load centres becoming smaller and less essential.

      • Andrew Woodroffe

        I am talking very short time periods, shorter than switching. Also, not much hydro in WA or SA. I agree voltage control will become easier with more and smarter distributed generation.

        • Cooma Doug

          The voltage and spinning reserve issues so deep in the soul of large scale base load grids, vanish with each coal generator.

          • Andrew Woodroffe

            Are you suggesting that the need for very tight frequency control is driven mainly by the the need for it of the large scale coal generators, themselves?

          • Cooma Doug

            On the load side and generation side the design of electrical plant is closely aligned to the frequency of the supply. In the Usa the frequency is 60 hz. You must appreciate that the steel in transformers and generators perform in a frequency range within 3% of the design frequency. Near this limit and outside it things are unstable and will fail causing a cascade colapse of the system.
            However, this has been true and always will be but now we can switch loads to manage it in smaller areas in time frames that minimise the impact on distant plant.

          • Cooma Doug

            If we measure frequency in the first 5 milliseconds of a cycle, then respond with milli second switching of load on the load side of that meter point, that area of the grid can behave as if an island and independent of the grid. If such loadside frequency response could be adopted behind all meter points, including the integration of batteries….problem solved.

        • john

          About 2 years ago the HV was put up in this area so that the resultant LV was lifted to about 249 V this resulted in most Solar systems cycling off due to high voltage output due to resistance in old small copper supply lines.
          Not many people who have PV know about this.

    • Andrew, Spoken like someone that understands power systems!
      The other advantage of course is the spinning inertia can help control the reactive (kVAr) requirements.

      • Andrew Woodroffe

        Inverters, if given sufficient time and smarts and network cooperation can also absorb or inject VARS. What I am thinking of here, is a very cheap way (kit already exists) of having a degree of inertia on a very inverter intensive grid over extremely short periods of time.

  • Cooma Doug

    There seems to be a general acceptance that the only answer to reduced frequency is more generation. This not so. Reduced load is a better option. There are many ways this can happen and in the future grid…simple.
    Most homes could switch off load at any time of the day in response to frequency measured on the load side of each home meter. This could be done with no disruption to the home life. As the generation becomes more widely distributed throughout the load areas, large 600mw plus gen losses will disappear. Its going to get easier not more difficult.

  • john

    We are looking at Hz ok i go check it.
    Hz 50.01 volts 246v

    Often the Volts are between 249 to 252 v and Hz will vary between 49.9 and 50.2 Hz

    The reason for the low voltage has to be high usage of AC because it is about 30c no wind and high humidity ATM.
    Results in high demand for power.

    • And the point is???

      • john

        What has happened is that the HV voltage was put up by 500 volts resulting in lifting the LV voltage by about 4 to 5 volts with the resultant outcome that that at 6 am in the morning the voltage is 249 v so as soon as a RE system tries to work it will trip after about 3 hours.
        If you monitor the Hertz you will notice it changing as more power is put in or more is drawn.
        If you have a PV system please check it all the time to make sure it is not tripping because of high resistance between your house and the grid and also make note of the voltage of the grid and your voltage to supply.
        The difference is caused by the voltage needed to push the power down the small cables which used to be 6mm copper and do cause rather a high voltage rise to achieve this.

        http://ipdgroup.com.au/ipdwc/VoltageDrop.aspx

        Perhaps the link will help just put in 6 mm cable and 100 metres and you will see the Voltage Rise need to use it.

        • Thanks John, I see where you are coming from.

  • Malcolm M

    If frequency regulation is the main service purchased, could battery-based systems provide additional power at the second to minute timestep more cheaply than running (say) a gas unit especially for this purpose ? As for rapid reductions in power output for over-frequency control, gas or hydro units have provided this service to date by rapidly reducing output, but could these services be provided on the second to minute scale more cheaply by a series of resistors in a a boiler of a steam-based power station ? This could be combined with gas or solar thermal storage. If their generation capacity is not required at the time, these units have cooling systems for heat disposal.

  • Ian

    My understanding is that as load increases it effectively draws more energy from the spinning generator slowing it down, less current draw and the generator speeds up. Solar generators, battery storage, and wind generators must surely have electronically controlled frequency generation and modulation. The modern grid must have other ways of controlling frequency other than relying on a huge coal powered spinning generator? Would this indicate the need for pumped hydro or flywheels to provide a spinning reserve? You would think power electronics would have this need covered.

    • Andrew Woodroffe

      Batteries, PV and some wind turbines are all fully inverter generators, meaning they contribute little to fault levels and have no spinning inertia which is different to spinning reserve. Spinning reserve is activated by a change, and something has to be turned up (or off in the case of loads). I expect batteries to do this job some time in the next ten years. Spinning inertia is the system’s resistance to change – the shorter the time after the event, the more effective and important it is.

      However, it has be asked whether such high frequency stability standards are really only required for the big thermal generators themselves. Once they are gone, maybe we won’t need such stability.

      My comment below about keeping old coal power stations spinning (BUT not generating!) was a cheap idea to maintain the spinning inertia if it were truly required by the network. Spinning reserve (by generator, battery or load) would still be required and would be supplied by other facilties.

  • George Papadopoulos

    Evidence that wind energy is contributing to ever rising retail prices. Wind energy is “cheap” at the wholesale level, just that someone has to pay for the red carpet to be rolled out to make it look glorious and effective.