A sample of five historic CBD projects was reviewed to estimate the historic asset utilisation at the time of augmentation of CBD three feeder mesh networks. For the CBD three feeder mesh network segment, there was no change in Energex’s TMU hence, the historic utilisation threshold was used as the forecast parameter. For the CBD two feeder mesh network segment, was no change in Energex’s TMU however, sufficient historic projects were not available to estimate the historic asset utilisation at time of augmentation. The utilisation threshold for this network segment was estimated based the CBD three feeder mesh parameters taking into account the difference in TMUs of three feeder mesh (66% TMU) and two feeder mesh (50% TMU) networks. Sources The NetPlan database was used to provide historic utilisation at time of project commissioning. Assumptions The following assumptions were applied to derive the utilisation threshold statistics to HV feeders: The difference between new planning TMU and average utilisation threshold will remain the same for radial network segments. The difference between the historic average utilisation threshold from sample projects and the TMU was maintained but increased to reflect the increase in TMU used by Energex for radial feeders. The difference between the planning TMU and average historic utilisation threshold was consistent between CBD feeder mesh and CBD two feeder mesh network segments. Distribution transformers (including LV) network segments Energex applied the same methodology to all distribution substation network segments, being the segments in the following AER segment groups: Distribution substations - CBD (including downstream LV network) Distribution substations - urban (including downstream LV network) Distribution substations - short rural (including downstream LV network) Methodology Energex has not historically recorded the utilisation of time augmentation for distribution substations in a corporate system. The mean utilisation threshold for the purposes of the Augex model was therefore provided for distribution transformers and LV network segments based on Energex’s Plant Rating Manual. Specifically:
A sample of five historic CBD projects was reviewed to estimate the historic asset utilisation at the time of augmentation of CBD three feeder mesh networks. For the CBD three feeder mesh network segment, there was no change in Energex’s TMU hence, the historic utilisation threshold was used as the forecast parameter. For the CBD two feeder mesh network segment, was no change in Energex’s TMU however, sufficient historic projects were not available to estimate the historic asset utilisation at time of augmentation. The utilisation threshold for this network segment was estimated based the CBD three feeder mesh parameters taking into account the difference in TMUs of three feeder mesh (66% TMU) and two feeder mesh (50% TMU) networks. Sources The NetPlan database was used to provide historic utilisation at time of project commissioning. Assumptions The following assumptions were applied to derive the utilisation threshold statistics to HV feeders: The difference between new planning TMU and average utilisation threshold will remain the same for radial network segments. The difference between the historic average utilisation threshold from sample projects and the TMU was maintained but increased to reflect the increase in TMU used by Energex for radial feeders. The difference between the planning TMU and average historic utilisation threshold was consistent between CBD feeder mesh and CBD two feeder mesh network segments. Distribution transformers (including LV) network segments Energex applied the same methodology to all distribution substation network segments, being the segments in the following AER segment groups: Distribution substations - CBD (including downstream LV network) Distribution substations - urban (including downstream LV network) Distribution substations - short rural (including downstream LV network) Methodology Energex has not historically recorded the utilisation of time augmentation for distribution substations in a corporate system. The mean utilisation threshold for the purposes of the Augex model was therefore provided for distribution transformers and LV network segments based on Energex’s Plant Rating Manual. Specifically: