Wind and solar farms face tough new connection hurdles

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Rule changes proposed by AEMO in response to the grid’s rapid transition to renewables have sparked vigorous debate about what precautions are necessary, and what are just “gold plating” generation assets.

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The pace of confirmed and aspirational wind and solar projects in Australia continues at breath-taking speed, with 30GW of proposals in Queensland alone, but developers face new hurdles that some fear will add unnecessary costs.

The changes have been proposed by the Australian Energy Market Operator in response to changes to the grid, and particularly the increasing share of renewables and the decline of traditional “synchronous” generation.

It has sparked a vigorous debate among energy experts about what rules and precautions are needed as the electricity system undergoes a transformation as profound as that from analogue to digital.

Where once the grid was dominated by machines that provided different ways of boiling water, the current technologies propose completely new operating principles. And many are learning as they are going.

AEMO has been quietly updating requirements for new and existing wind and solar projects, notably since the South Australia blackout revealed that there was a lot about the performance of generators – both wind and fossil fuel – that it did not know.

The first act was to change the software settings on certain wind farms to improve their ability to ride through the series of catastrophic faults that hit South Australia’s grid when the cyclonic winds blew down three major power lines.

Then came the imposition of “continuous uninterrupted operation”, which requires a wind and solar farm to maintain performance, all things being equal, through a major fault.

It wasn’t a particularly controversial rule, but the fact that it required some added expense, and was imposed on some projects even after contracts were signed, caused grief to some developers and their contractors.

Wind and solar farm developers are also coming to grips with changes in marginal loss factors, which decides how much of their output gets credited in the grid, and warnings of potential curtailment because of over-build in areas with weak networks.

The latest suite of proposals include updated requirements on the ability of wind and solar plants – and all other new and some existing generators – to provide responses to frequency, voltage control, reactive power and system strength.

Most – but not all – have been approved by the Australian Energy Market Commission, which acts as rule-maker, and are included in a dense compendium of more than 300 pages of largely technical discussion.

AEMO argues that it wants to make sure the grid is ready for the massive changes that will occur over the next decade, and the one following, when only the most stubbornly pro-coal supporter would believe that the grid would not be dominated by renewables and storage.

It argues that rather than starting at the base and working up, it wants to start at the top and negotiate down. It makes sense to the operator, but has sparked accusations of “gold plating” from the industry players.

And while the industry has no problems with some of the new rules and requirements, there remains controversy over others, and the manner of implementation.

It could affect wind and solar farms which have approval, have signed contracts but have yet to finalise the details of connection agreement. And the owners of existing synchronous generators are also complaining.

Part of the problem is the speed and depth of the change in the way electrical power is used, and the varying expert views of how this can and should be managed.

There is an intense engineering debate about the transition to a renewables-based grid, which is being accelerated by the plunging cost of wind and solar technologies, and also battery storage.

The varying technical views are visible in the difference between AEMO and AEMC assessments, particularly in their views on system strength (where the AEMO proposals were rejected by the AEMC), in the difference between the operator and the grid owners in some key sections, and, unsurprisingly, between traditional (fossil fuel) and modern (wind and solar) generators.

The AEMC document reveals plenty of examples where developers of all types warn of un-necessary added costs, particularly in the area of “remote monitoring”.

In one example, the Clean Energy Council points to a proposed requirement to be able to “monitor” the amount of energy in a battery, which the CEC said would provide “nothing informative”, because it did not indicate what this energy was designed to serve, and whether it was assigned for network services.

Renewable energy groups such as Pacific Hydro, RES, and Esco Pacific warned of the risk of higher costs, as did major utilities such as Alinta, Origin Energy and Hydro Tasmania, who also noted that imposing some capabilities such as remote monitoring on existing generators would impose material costs.

Many warned of the risk of ‘gold plating’ connecting generators, installing capabilities that are not required in many locations in the power system, representing inefficient costs that need not be borne by consumers.

Some considered the new standards to be among the most stringent in the world, and many were concerned that AEMO and network service providers already had too much power in negotiations over connection approvals.

Despite the quibbling, most analysts and experts agree that several of the rule changes are overdue, such as the ability for all generators to be able to contribute to the control of system voltage and frequency, particularly if the system is to transform to very high (up to 100 per cent) renewables.

The most controversial proposed rule change appears to be one that requires generators to be able to ride through 15 faults on the power system within a period of 5 minutes.

Bruce Miller, an energy expert with advisory group Advisian, says this is typically impossible for traditional synchronous generators to achieve, an assessment shared in their submissions by the likes of GE Australia, Hydro Tasmania, Pacific Hydro and Stanwell.

Miller says that converter-connected plant on the other hand (which newer wind and solar farms utilise) can theoretically comply, but often only if the plant is oversized to cope with the extra thermal requirements that would result. And that would result in added expense.

“A key issue that seems to have been discounted by the AEMC, is that if any portion of the NEM were to experience 15 faults in 5 minutes it would almost certainly break up because virtually nowhere on the NEM do we have 7 or 8 transmission lines maintaining network connectivity (lines will trip if a fault and reclose operation is unsuccessful – thus it is possible for a single failure to cause two faults in close succession,  but three would normally cause a line trip and lockout).

“The proposed rule change treats synchronous and asynchronous generators differently which is counter to a principal of the NEM”, which until now has strived to be technology neutral.

“In consequence the draft rule on face value treats different generation technologies differently, will add significant cost to new renewable generation technologies for non-credible contingent conditions which if they were to occur in practice would almost certainly result in the breakup of the transmission system.”

The debate over “system strength” is an area that is running hot with debate.

Miller, who has written some interesting and important articles about the issue of inertia that have been published on RenewEconomy (See: Inertia: We don’t actually need that much) is also a critic of the approach of AEMO and others on “this issue.

“The whole issue of ‘system strength’ needs to be critically examined…the necessary requirement for system strength as promulgated by various authorities needs to be clarified and the recent statements debunked if necessary,” he wrote in his submission.

The AEMC noted that “a number of stakeholders also explicitly opposed the proposed access standard in its current form, or disagreed that there is a need for a system strength standard to be implemented.

“This included owners and developers of primarily asynchronous (but also some synchronous) generating systems, as well as consultants.”

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