Figure 24 Distribution of BESS VAr absorption across 24-hours from AGL VPP sites
6.3.2 BESS and D-PV Volt-VAr curves Both D-PV and BESS inverters are expected to inject or absorb VArs based on the experienced voltage conditions according to the rules defined in Australian Standards AS/NZS 4777 (i.e., Volt-VAr settings). The inverter’s VAr behaviour will also depend on its installation date and the respective standard version that was in place at that time, since newer standards have different settings compared to legacy standards (see Figure 9). The AGL VPP dataset does not include any information regarding the inverter settings or the version of the standard that applied at the time of installation. Therefore, it was found useful to investigate scatter plots of the VArs vs. voltage to identify which V-VAr curve each BESS inverter operates according to. Figure 25 shows VAr vs V scatter plots for 12 months from the BESS inverter which had the highest VAr response amongst 996 sites from the AGL VPP dataset. As per the site monitoring sign convention, absorbing VArs are denoted with negative values and injecting VAr are denoted with positive values. It is observed that this BESS mostly operates according to the TS-129 V-VAr curve characteristics (see Table V). It is also seen that there is VAr injection at the 0.08 VAr/VA_rated level across a wide range of voltages which is consistent with the previous finding where BESS injected constant quantity of VAr across the DPV generation window. As voltages go lower than 220 V in winter months, there are higher levels of VAr injection as per the TS-129 V-VAr requirements.
44 | P a g e
