Today wind capacity in South Australia stands at 2500MW, contributing to almost 40% of the energy generation in the state. This is in addition to utility-scale solar and rooftop PV, which contribute 4% and 15% of total generation in SA, respectively. With such a high level of variable renewable energy (VRE) penetration, inertia becomes important. Inertia refers to the energy available from large rotating generators. This inertial energy can be valuable when a large power plant fails, as it can shore up small variations in system frequency. Synchronous Condensers (syncons) have been used to provide inertia to the grid and provide system strength.
In August 2021, the first out of four syncon machines came online in SA. This was followed by the other three syncons becoming online and passing tests in the next months (two at Davenport and two at Robertstown). Since then, SA has seen a considerable reduction in the number and cost of market interventions (when directing a gas or diesel generator to maintain system strength).
The installation of the syncons also resulted in more utilisation for VRE generation by allowing their limit to increase to 2,500MW with just two gas units operating. This limit which AEMO determines was 1,700MW before the installation of syncons. In this Chart of the week, we look at the monthly energy balance of SA before and after the installation of the syncons to investigate the effects of these machines on SA’s network.
The chart shows that wind generation has considerably increased since the installation of syncons in August 2021. This also resulted in a reduction of gas in Q4 21 because less inertia is needed from gas plant turbines in the presence of syncons.
Note that the increase in gas during May-July 2022 was due to elevated prices before, during, and after the market suspension, a unique circumstance partly driven by geopolitical factors.
To highlight the overall effect of syncons on VRE and gas generation, Figure 2 shows the average generation for 8 months before and after the installation of syncons. As seen in Figure 2, average wind generation has increased by 125.4 MW while average gas generation reduced by 118.2 MW. Solar generation did not see a considerable difference due to the small capacity of solar in the state.
All in all, it can be seen that syncons kept their promise and resulted in what we expected them to, i.e., compensate system strength shortage due to gas plants not operating and unlashing the VRE potential. The next question will be how much more syncons we need in SA to achieve net-zero targets while maintaining the inertia requirements in the state.
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