Demand Forecasts For The Forward Planning Period

The Endeavour Energy transmission and zone substation peak demand forecasts are provided in the DAPR Mapping Portal , covering the peak demand forecast by season for the 2022 – 2026 period. The peak demand forecasts provide Endeavour Energy with the basis for identifying network limitations and commencing the RIT-D process to identify and evaluate the credible network and non-network options to address those limitations. They also feed into the Portfolio Investment Plan (PIP) which documents the capital and operating investment expected to be required for a rolling ten-year period.

Growth in peak demand is a key driver of network-capability related capital investment. In the previous decade the growth in demand was fundamentally driven by an increase in residential, commercial and industrial development areas within the priority growth areas of Western Sydney and the Illawarra. In some cases, it may also be a driver for asset renewal investment.

In recent years the penetration of air-conditioning appears to have reached saturation point in some areas of our network. As a consequence, peak demand growth from existing connections no longer presents a significant driver of network expenditure. Furthermore, demand in recent years has seen a decline due to the effect of energy efficiency measures, the roll-out of roof-mounted photovoltaic systems and reductions in the demand from large industrial customers. It is further expected the energy efficiency measures and the installation of photovoltaic systems, coupled with the forecast increase in battery installations, will continue to influence a reduction in demand over the forecast horizon for established areas. However, the rate of adoption of electric vehicles in the medium term will change the demand profile and could lead to growth in peak demand again.

Demand growth is primarily concentrated in North-West and South-West Sectors of Western Sydney. Widely regarded as the fastest-growing corridor in the state, priority growth areas in Western Sydney are expected to accommodate up to 480,000 new dwellings and land for employment for around 1,000,000 new residents over the next 25 to 30 years. Strong economic growth is expected in the growth centres over the forecast period, with a series of major transport, health and education projects planned for the region. Development of Sydney’s second airport at Badgerys Creek and the establishment of a third city has commenced and will drive further demand growth in the future. The North West Rail Link has also created new high density residential and commercial development in the North-West Growth Sector. Similar developments are expected in the Glenfield to Macarthur rail corridor.

The Endeavour Energy Network total demands for the 2021/22 (2022) summer peaked at 3,716 MW at 15:30 on 1 February 2022 (Tuesday) while the temperature recorded at Richmond was 33.2 ºC at 15:30 on that day. The maximum temperature recorded at Richmond was on 18 December 2021 and demand at this time was 3,367 MW.

Figure below shows the time series of the daily maximum temperatures at Richmond and the peak demands on the Endeavour Energy network and NSW during the 2022 summer peak demand period.

Note: Peak demand during non-working days are shown in lighter colours.

Forecasting methodology

Peak demand forecasts are prepared for both the summer and winter season. Summer is defined as the five-month period between November and March while winter consists of the four-month period from May to August. The forecast method is based on a bottom-up approach and provides maximum MVA, MW and MVAr loads and the power factor expected for the summer and winter peak periods.

The forecasts are prepared for each zone substation and major customer substation, each transmission substation and TransGrid’s Bulk Supply Points (BSP) that supply the Endeavour Energy network. The total Endeavour Energy network peak demand is also forecast.

The forecasts consider planned load transfers, expected spot loads, land release developments and redevelopments in the area under consideration. Loads supplied by generation embedded in the network are also incorporated into the calculation of the maximum demand forecasts.

Historical and forecast peak demands at the Endeavour Energy total, bulk supply point, transmission substation and zone substation levels are corrected to normalised figures that represent a specific weather condition. Temperature Corrected Maximum Demand (TCMD) is the estimate of the likely peak demand that could be expected in the reference conditions with 10% and 50% Probability of Exceedance (PoE).

Weather correction is applied to the peak demands at substations where there is a strong relationship between demand and temperature. Summer demands at zone substations in the Blue Mountains and demands of all high voltage customers are not subject to any weather normalisation. However, the Blue Mountains substations are subject to weather normalisation for winter peak demands.

A weather normalisation methodology based on a simulation approach is used to normalise peak demand forecasts for Endeavour Energy’s network area. Two reference weather stations are employed for temperature correction of the maximum demand for summer. A weather station at Nowra is used for the South Coast area which covers the Dapto BSP Region and the Richmond weather station is used for the remainder of the network.  The temperature correction method utilises two steps:

• development and updating of a regression model for estimating the relationship between demand, weather and periodic pattern (calendar effects) of demand, and
• simulation of the demand using multi-years of historical weather data to produce 10% and 50% normalised demand values.

For the summer peak, the regression model uses the most recent six years of daily maximum demand and temperature values to determine the relationship between demand, weather and periodic patterns of demand. Various input parameters are employed in the model. Day-of-the-week variables account for the difference between the daily peak by day of the week and by workday/non-workday. A set of holiday variables are included to describe the load reductions associated with holiday periods. Separate variables are used for special days such as: New Year’s Day, Australia Day, and Christmas Day. In addition, a school holiday variable captures the reduced loads which occur in residential Western Sydney during the school holiday period in December and January and the commensurate increase in demand seen in some south coast zone substations during the same period. Monthly and bi-monthly variables capture the key seasonal demand variations. Year variables describe the changes in base load level for each year. Previous hot day effect variables are also included to explain the impacts of successive hot days on the daily peak demand.

From the regression model, daily demands are estimated using 24 years of daily weather data available from the reference weather stations. Annual seasonal maximum demands are derived from the calculated daily demands. The 10% and 50% demand values are computed from the distribution of annual seasonal maximum demands to give the 10% and 50% PoE TCMD values. The TCMD values for the latest year are the starting points for the peak demand forecasts.

The peak demand forecast considers the growth or decline from the existing customers as well as the new customer connections. The forecasting process has two major steps:

• incorporating the network planner’s inputs into the base level forecast.

The inputs include new developments planned to occur (lot releases), new load increases expected from customer applications (spot loads) and information regarding the transfer of load between zone or subtransmission substations (load transfers).

• applying post model adjustments (PMA).

PMAs are applied to each year of the forecast for each zone substation based on the zone substation’s residential, commercial and industrial customer mix and its peak demand for the season. PMAs are designed and used to capture future changes in the peak demand resulting from solar generation, battery energy storage, electric vehicles and from different state and national energy policies/programs, such as the Minimum Energy Performance Standards (MEPS), NSW Energy Savings Scheme (ESS) and changes to the building code.

The final forecasts for all zone substations are reviewed for consistency with expected demand growth based on local knowledge of load transfers, embedded generation, proposed spot-loads and lot release information.

The forecast at transmission substations and bulk supply points is based on the rolled-up zone substation forecast and calculated using the corresponding historical diversity factors.

The diversity factor is considered to be the ratio between the summation of the individual peak demands of the lower level substations and compared to the measured peak demand of the higher-level substation for the same period.

Forecast input information sources

Demand and temperature data is sourced from Endeavour Energy’s Historian databases. Data from the SCADA system is used as a substitute where gaps exist in the available metering data in Historian. Where neither metering nor SCADA data is available, the measured current flow readings from the current transformers on individual circuit breakers are used.

Assumptions applied to forecasts

The following probability of exceedance (PoE) parameters have been adopted:

• 1 in 10-year event (corresponding to 10% PoE), and
• 1 in 2-year event (corresponding to 50% PoE).

A 10% PoE figure is estimated to be exceeded once in every ten seasons on average whilst a 50% PoE figure is likely to be exceeded every two years on average.

The installed and firm capacity of each substation and the capacity of the sub-transmission system are shown in the forecast tables are indicated by a single figure. This figure is the summer rating for the subtransmission system and each substation.

The determination of the load transfer capability for each substation involves the analysis of individual distribution feeders and their ability to carry additional load after network switching occurs. Consequently, this is only performed for substations that are experiencing limitations and may need to be offloaded. The analysis involves determining the load that could potentially be transferred away from the constrained network on a permanent basis.

Demand forecast

The capacity, forecast demand and any network limitation on each of the transmission and zone substations on the Endeavour Energy network and on the associated sub-transmission networks are listed in the DAPR Mapping Portal https://dapr.endeavourenergy.com.au. The RIT-D level identified network needs are summarised in Table 6 and Table 7 in the DAPR report.

Limitations are referenced to the design level of supply security at each substation. In general Endeavour Energy assesses its network capability on the basis of providing an “N-1” level of supply security at the subtransmission and zone-substation level, however small or temporary substations may operate in a nonsecure manner and these are marked as limited to N. Generally, these have maximum demands of less than 10 MVA. This approach serves to identify preferred future network development options should future limitations be unable to be mitigated through Demand Management initiatives. The actual investment timing is confirmed through a probabilistic assessment of the network risk and the optimisation of the economic benefits of any proposed development.

The substation total (installed) capacity is the maximum load able to be carried by the substation with all elements in service. The secure capacity of a substation is the capacity with one major element (such as a power transformer or sub-transmission feeder) out of service. This is often referred to as its “Firm” or N-1 rating.

Transmission substations are considered to be constrained when the load exceeds the secure capacity. Suburban zone substations are considered to be constrained when the demand exceeds the firm capacity which is the trigger point for commencing investigations for cost-effective options to address the limitation. The exception are substations whose rating is limited by underground feeders or where exceeding secure capacity will result in the thermal rating of apparatus being exceeded in its normal configuration. In these situations, the load may not exceed the secure capacity of the substation for any period of time.

The voltage levels of Endeavour Energy’s sub-transmission substations (termed ‘Transmission substations’) are nominally 132kV on the primary and either 66kV or 33kV on the secondary. The voltage levels of Endeavour Energy zone substations are nominally 132kV, 66kV or 33kV on the primary and 22kV or 11kV on the secondary.

The forecast is prepared following the end of each peak season. The zone substation rating changes have only been included where the associated project(s) which are influencing the rating have been given approval and are committed at the date of preparation of the forecast.

The forecast power factor readings correspond to the power factor at time of peak load. A dash in this field indicates that the particular transformer was either not commissioned at the time of measurement or is normally unloaded.

Forecast demands for the sub-transmission feeder network are based on its ‘N’ rating, summer or winter, and the ‘N-1’ loading, that is, the worst condition load that would appear on the feeder with an adjacent feeder out of service compared to the thermal rating of the smallest conductor or cable on that feeder.

The ‘95% Peak Load Exceeded (hours)’ figure in the Transformer Rating and Substation Details table represents the number of hours the load is above the 95% level of actual peak demand. It is an indication of how peaky the load profile is which is important for designing an effective non-network option.

The ‘Actual (MVA)’ figure that appears in the summer and winter demand forecast tables is not temperature corrected. It is the actual recorded load. The forecast loads are based on temperature corrected actuals.

The ‘Embedded Generation’ figure that appears in the Transformer Rating and Substation Details table provides the estimated aggregate level of embedded generation connection to the network supplied from that substation. It includes residential and commercial PV and customer generation. Customer details are withheld for privacy reasons.

The summer 2022 refers to the 2021/22 summer.

The transmission-distribution connection points are termed Bulk Supply Points (BSP) and are owned by TransGrid, the NSW transmission company.

Endeavour Energy evaluates the capability of its sub-transmission network on the basis of load flows modelling different contingencies and network operating configurations. The sub-transmission forecast tables in this document are desktop estimates derived from zone substation load forecasts and are based on an assumed operating configuration and on the present-day network. The loads presented are indicative of the load on the stated feeder in the event of the most likely contingency. Hence, the sub-transmission forecast tables should therefore be treated as indicative loading data in the event of a credible contingency event.

Analysis and explanation of forecast changes

There have been minor changes occurring within the customer groups that has an effect on demand on the network and the demand forecast. These include:

• An increase in areas prioritised for development by the NSW government. This is reflected in our Growth Servicing Strategy.
• The Western Sydney Aerotropolis showing increased load growth from 2022 onwards.
• continuing focus on redevelopment of existing areas especially along rail corridors; and
• A number of large  customer applications and connections in the Western Sydney area, particularly data centres, which has dramatically increased demand forecasts in this area.

Certain areas in the priority growth areas have accelerated their lot release projections as well as densities resulting in increased levels of demand growth. However, all lot release projections are diversified to account for the lag in housing development.

There has been unprecedented and significant rezoning of employment lands, particularly in and around the aerotropolis precinct which needs to be closely monitored together with the electrification plans for commercial vehicle fleets.