Editor’s Note – This is the text of a speech presented by Kate Summers at the Clean Energy Summit in Sydney on Wednesday 19th July 2023.
I cut short my skiing holiday to prepare for today. Shows how serious I am about speaking to you today. Actually, it was too warm to snow, it rained.. a sign that El Nino is approaching.
When I examined the topic “systems and markets” .. for a high renewable future, I got a bit frustrated as it is clear to me that we are losing sight of the true purpose of generating electricity. Our over arching aim as a society is to eliminate emissions from fossils fuels in order to counter and reverse the rate of change that is occurring to the climate. The announcement from Anna Collyer at the Energy Week regarding 3.5 Million installations of residential PV and how the AEMC was figuring out how to “run the system” from them, along with Daniel Westermann stating that we are redesigning the airplane while flying it, has a number of power engineers worried while all the moving parts in the system don’t appear to be coming together coherently and some appear ill informed with power system basics.
It was good to hear Chris Bowen articulate that nuclear is a distraction and frankly watching the domestic nuclear power stations being weaponized in Ukraine should tell everyone that it is not an intelligent or wise option. After all, nuclear energy is just used to boil water. If we think about it, we could boil water from excess wind and solar power, problem solved, no underwriting, no ten thousand year radio active waste.
I’ve been around the industry long enough to observe the trends, I’ve lived the policy roller coaster. I have witness the enthusiasm of the companies to race to have projects across a portfolio of technologies. But I worry that as an industry the rush to embrace the new risks throwing the baby out with the bath water. The impact and cost to “maintain” system strength highlights this, the adoption of synchronous condenser as the solution, is just an alternator without a drive shaft providing the electromagnetic solution. Its expensive and could be wasteful as technology (in inverters) is already well progressed and can solve the problem, but we will find very large costs applied throughout the network for a problem that good control engineering could solve.
It is time to ensure power engineering as a discipline provides leadership to ensure that the in flight redesign of the system does not catastrophically dive into a mountain. 200 years of scientific curiosity and experiment in electromagnetism coupled with 100 years of engineering research and knowledge set how we safely control electricity, particularly 3 phase AC electricity that provides the reliable, affordable and safe supply of quality electricity.
As disruption seems to be the flavour of the day, we must recognise the risk, understand the science and the cost if it goes wrong. We cannot afford to collapse the system that underpins our economy. Electricity is not a sector of it, but it is the enabler of our economic activity, let’s think carefully about what we are doing and how we are messing with it. Furthermore, as the electrical power system of a country represents its most expensive, most complex infrastructure, it is not easily replaced and it remains a three phase AC power system.
This requires proactive power and control engineering to implement the primary control functions that deliver a stable system and support the operational oversight of the system. It is through fundamental primary control that we find the solutions to keep electricity safe and fit for purpose. The regulatory system needs to respect engineering, enable engineering to make decisions, allow the use of discretion, engineering reason and judgment so that we can practice in accordance with the ethics of our profession. We need an environment that prioritises engineering decisions to achieve outcomes that obey physics and good control practice.
Economic outcomes are an externality to the power system and must remain an externality, driving power in accordance with price alone will not ensure it is safe or stable. It was a pleasure to hear Chris Bowen state that the NEO was finally incorporating an obligation to reduce carbon emissions, something we argued for in the naughties, but it was always dismissed by the economists as an externality.
Twenty years of the market shows us that regulations take a long time, often contain errors, that don’t get acknowledged and some errors can take time to appear. Further rules changes often complicate what has already become a twisted risk shifting cost allocating compliance nightmare. The NEM commenced with the intention of light handed regulation, the transmission systems being monopolies required regulation. The commercialization of connections is not healthy, the open access regime has enabled and allowed over subscription to lines that were designed for rural electrification.
Setting aside the transmission challenge, I want to examine trends in the distribution systems reversing power into the HV power system, given the dramatic news that electricity bills will increase significantly, this no doubt set the installation rate of residential PV into overdrive.
The rate of this uptake presents a security and reliability risk that requires appropriate pro-active engineering solutions. While DER and VPP aggregation is in train with trading of power at the street level, and a number of other initiatives, it is important to note the concern of the system operator regarding the failure of the residential PV inverters to conform to the latest standard. I think trying to solve control of rooftop solar at the house level is problematic, the horse has bolted, the community installing PV wants to see it deliver a better future, not a failed electrical system. Its important from a social licence point of view that engineering solutions are not reactive, not heavy handed or overly intrusive with BTM constraints.
I want to step through some simplified concepts to aid informing the industry of why consistent engineered solutions are required in the distribution system. We have a 3 phase AC power system, this is generally described with power flowing from the generator to the load. This is true regardless of the location or the network, power takes the shortest path to ground.
In the context of the power system we know that AC power in a three phase system is always controlled to match the demand. Here’s an older hydraulic analogy of both a single phase and three phase system. Consider the generator is rotating a crankshaft that produces an equivalent sinusoidal wave that drives the crank on the motor.
Ref: O Elgerd: Electric Energy Systems Theory: An Introduction. Pg.27
In a three phase system the load is balanced on all three phases, this is illustrated by the crankshaft with each crank at 120 deg apart.
Ref: O Elgerd: Electric Energy Systems Theory: An Introduction. Pg.27
It is easy to see that all the power put into the system is continually used at the end of the system. The power in must match the load plus the losses.
Its not too difficult to see now that if the load is unbalanced between the three legs, the forces will distort the crank and neutral will no longer be neutral.. or the centre of the crank is offset. This causes a number of safety issues across our network with negative sequence voltages, circulating earth currents that over time will lead to elements in the earth becoming sacrificial and corrode much faster than they should. This is not a safe outcome.
This is why in NER schedule 5.1, clause S5.1.7 regarding the design and operation and control of networks, there is a clear obligation to maintain balance, in a distribution network this is written as an obligation to balance phase current drawn from the system, but it should not require a redraft for NSPs to know that balance also applies to generation.
Before I move to system implications, let’s continue to consider the risk of elevated voltages at the 240 V supply level for residents. These networks are graded from the zone subs out and most have fixed transformer taps along the feeders, anyone who has tried to connect into a lower voltage distribution line will understand the impact of generation and the need for reactive power to control down the supply voltage. The same problem will be present in the distribution feeders where exported residential PV power elevates a phase voltage. It is likely that neighbouring houses on the same phase are exposed to high voltages, the consequence of which is likely to be damage to appliances or in the worst case, risk of house fires where there is aged wiring or perhaps hungry rats having a chew. This means there is a strong safety imperative for proactive engineering control within distribution networks to ensure control of voltages and excess power.
Reactive engineering controls that switch off residential PV will be seen as wasteful, it will annoy customers some of whom will exit the network. As it becomes a regular occurrence the more annoying it will be. Setting up a regulatory environment that enables this will pitch the power industry against the customers with PV, it will take years to unravel and does not resolve the unbalance or high voltages that occur. Engineering distribution feeder level solutions that control and rebalance the 3 phases is an imperative that goes beyond the nice to have market solutions, it calls for a meticulous, methodical disciplined program to locally store the excess energy and provide primary controls that rebalance in real time the voltages. While some claim the cost is too high, I think pink batts on steroids, lets plan and deliver systems that keep the power system safe.
Back to the power system and why local storage? A brief overview of the structure of the power system.
The direction of power flows from generators to loads, this fact is not alterable, while some generators can become motor loads, (such as pumped hydro) or batteries can be in charge mode, the direction of flow is the same. Traditionally, the control philosophy requires sufficient generation to be available to replace the loss of the largest generator in order to maintain supply to the load. .
The available generation to meet forecast maximum demand is critical, but so to is understanding the ability of the system to withstand load rejection at the minimum demand. In the 1990’s this would have been loss of an aluminium potline at 4 am in the morning. Today this would mean loss of an aluminium potline or the largest load anywhere between 12 – 2 pm and at 4 am. The ability for generation to remain stable through low load is a challenge for thermal and gas generators, we know there are technologies that can seamless ride through no load, but what happens if the system is saturated with power?
This brings me to the forecast minimum sent out demands, I refer here to the mainland NEM states. SA is already at or about negative minimum demand with VIC following close behind and NSW and QLD looking odd in 2030. In operational system forecasting the concern is always about coincident peak demands, they can and do happen. Likewise the minimum overnight has always been around 4 am, and in a north south oriented system midday occurs at the same time in most state an only ½ hr behind in SA. Hence, when we examine the minimum demand in SA extends from around 11:30 to 15:00 in spring and summer, which is wide enough for Victoria to coincide with NSW and QLD not to far behind.
The 50 POE forecast means every other day this type of demand could be expected. The pattern of both wind and solar can be diurnal, with wind impacted by the heating and cooling of the ground coupled with the dawn or dusk. In SA this can create two periods of LOR.. (Slide11).
How prepared are we for coincide minimum or negative demands that are forecast to occur within 4 or 5 years? Production of uncontrolled excess electricity into the power system is destructive, whether at the LV or HV level, some consequences won’t be immediate, others will be explosive. Generators don’t like to motor, all generation has reverse power protection.
As a practicing chartered engineer, I am obligated to conform with the ethics of my profession. This includes providing a better future for the next generation, as Peter Cowling said in his speech last night – lets do this for our kids. But the regulatory arrangements implemented in the market expect black and white precision and conformance to the wording in the rules, this alone contradicts the ethics of engineering, fails to appreciate the complexity of the electricity and eliminates the use of engineering reason and judgement as due diligence processes have become fault finding exercises with problem solving something old engineers do. To achieve our targets, we must not trivialize or ignore the importance of power engineering to guide and inform the decisions regarding the control of 3 phase electrical power.
As we cannot control the renewable resource, but we must control electrical supply to the system, storage technologies must be critically examined for their strengths and weaknesses.
Pumped hydro will be limited in droughts, but has a long life.
Batteries cannot charge if they are full.
A colleague joked to me we could make money putting a resistor on the system.
The system must have access to bulk controlled load that is dedicated to storage, a portfolio of technologies with some being durable, long life bulk heat storage. This would be able to absorb excess power and then produce clean steam for electricity to fill the dunkelflaute. I consider the roll out of SCs to be wasteful, these machines will last 40-50 years, and instead of flywheels for inertia they should be coupled to a synchronous clutch, with a turbine and able to be driven from steam out of heat storage. Electrical equipment is expense, and should always solve more than one problem.
It is incumbent on the industry to provide the solution to the control of electricity rather than expecting the community to change their habits, alter their lifestyles or tolerate interference with their electrical needs while responding to a price signal. Expecting people to do this is industry failing to take responsibility for the provision and control of electricity that serves society.
We are fast approaching a cliff, the forecasts lead to negative load in many regions, SA and NT are already experiencing it. Participation of loads in the NEM has been possible since market start, but loads found it to intrusive their core business to continue, a market solution will not mature in time to avoid the cliff.
Are we prepared with controls that we know will work or are we meandering our way to reckless abandon the consequences of which create an expensive, unsafe and unreliable power system that fails the economic well being of the country?
About our Guest Author
|Kate Summers is a Fellow of the Institute of Engineers, and an experienced power systems and control engineer with extensive electrical experience, market and regulatory knowledge. She is passionate about renewable energy and dedicated to bringing about an orderly transition to a low carbon future. Her broad engineering knowledge has been gained over 28 years of engineering practice covering a wide range of practical field experience, power system analysis, transmission planning, operational control, regulatory compliance and project connection negotiation.
In 2020 Kate was jointly awarded National Professional Electrical Engineer of the Year for her work identifying the root cause of the deterioration in system frequency.
Kate’s recent focus has been on control philosophy, shedding light on the unintended consequences of market based decisions in respect of control theory, the loss of power system engineering practices and the escalating complexity of regulation imposed on engineering.
Current modelling practises are overly complex, devoid of clear purpose and extend beyond sound use of the mathematical methods. Computer models are a tool to aid engineering interpretation of the power system. Kate is an advocate for stepping back from detailed power system modelling to understand complex problems from fundamental principles aligned with power system control philosophy.
You can find Kate on LinkedIn here.