The subtransmission line tables include the following information:

• Planning Region
  • Ergon Energy Ecorp Asset ID
  • Ergon Energy operational number
• Subtransmission line description
• Summer capacity & load forecasts for 5 years
  • Rating (Amps)
  • Loading (Amps)
  • Power Factor

Definitions

SD: Summer Day (9am to 5pm)
SE: Summer Evening (5pm to 10pm)
SNM: Summer Night/Morning (10pm to 9am)
Summer: December to March

Comments

• Poor power factors of some feeders
  Where the power factors are very low it is because (in general) the feeder is part of a ring network with circulating reactive power. The active power is swamped by the reactive power in these cases. There are some radial feeders where the power factor is also very low. This is as a result of very little active power being supplied by these feeders combined with a lot of line charging reactive power which once again swamps the active power component.
• Missing power factors
  This is a result of unloaded feeders that are only energised from one side. There is some line charging which accounts for the non-zero loading in amperes but there is no active power supplied by the feeder.

The Substation Forecasts include the following information:

• Zone Substations
  A zone substation refers to an Ergon Energy owned substation that converts energy from transmission or subtransmission voltages to distribution voltages.
• Bulk Supply Substations and Transmission Connection Points
  A Bulk Supply Substation refers to an Ergon Energy owned substations that converts energy from transmission voltage levels to sub-transmission voltage levels. Some Ergon Owned Bulk Supply Substations contain asset boundaries with the Transmission Network Service Provider and therefore are also the Transmission Connection Point. Demand forecasts for other TCPs are reported in a separate workbook.
• Load Forecasts
  The summer and winter load forecasts are provided in the row named 10 PoE Load. (Note: The 50 PoE Load is used to address Safety Net requirements.)
  • "Hours PA > 95% Peak Load" gives the hours per year that load is above 95% of the peak load.
  • "zero' values occur for small substations with no metering installed to provide this data.
  • 'N/A' values occur for new substation which does not yet have history on this data to be able to determine future forecasts.
  The peak load given is a compensated load, which is the load with reactive compensation in service.
• Capacity
  Substation capacity is based on transformer ratings only.
• NCC (Normal Cyclic Capacity) Rating is the total capacity of the substation with all transformers in service.
• ECC (Emergency Cyclic Capacity) Rating is the firm delivery capacities with the largest transformer out of service.
• Transfer Capability
  The load transfer capabilities of each substation are broken up into the following categories:
  • Auto Trans Avail: Transfers conducted automatically by a distribution management system
  • Remote Trans Avail: Transfers conducted by a Network Operator located in one of the Operational Control Centres
  • Manual Trans Avail: Transfers which require manual switching by a field crew
  • Mobile Plant Avail: Supply which can be restored by the use of a mobile substation, HV injection generation or distributed low voltage generation
  The transfer capabilities align with the various time requirements to have certain load levels restored under Ergon Energy’s Safety Net requirements.
• Load Shedding
  The load shedding rows are defined as follows:
  • Shed (30min): Loads to large customers which can be disconnected by remote operation of switchgear.
  • Shed (4Hour): Loads to large customers which need manual switching by field crews to disconnect them from the network.
• Security
  

  The load at risk assessments (LARn and LARc) are assessments of the potential load at risk in a substation. If there are values in the LARn or LARc columns the “Meets Security Standard” row will change to “No” for those columns.

  The LARn is calculated by comparing the 10 PoE with the NCC rating. If the 10 PoE load is greater than the NCC rating then there is potentially load at risk under normal operating conditions for the substation.

  If there is a value of LARc then Ergon Energy may potentially fail to meet its obligations in the occurrence of a Safety Net event. The LARc value is determined as follows: The Raw LAR is arrived at by comparing the 50 PoE load with the ECC rating. If the 50 PoE load is the greater than the ECC rating then contingencies need to be in place to meet Ergon Energy’s Safety Net obligations. The transfer capabilities, mobile plant capacities and load shed allowances are then taken from the Raw LAR value to give the LARc value.

  For the implementation of Safety Net Ergon Energy operates two Substation categories.

  • Regional Centres are towns/cities with a population of more than 6000 people.
  • Rural/Remote is used for substations servicing all other areas of the state.

  The time required to restore certain load levels for each category is less for the Regional Centre category.

  Under Ergon Energy’s Safety Net large customers are exempt from reporting. While all efforts are made to restore supply to them, load shedding can be used to disconnect these customers from the network if required in a contingency event.

• Embedded Generation
  The embedded generation reported for the substation is the nameplate rating of embedded generation connected to the low voltage side of the substation.

The Transmission Connection Point Forecasts include the following information for 50 PoE and 10 PoE in summer and winter:

• Ergon Energy region
• TNI: National Electricity Market - Transmission Node Identity
• TCP Name: Name of the Transmission Connection Point
• Forecast Peak Load (MW)
• Forecast Peak Load (MVARu) (VARu = Volt Amps Reactive Uncompensated, i.e. with stated compensation not active)
• Forecast Compensation (MVAR)

Exclusions
Forecast capacity is not given this spreadsheet. In the majority of cases, the capacity at the TCP is controlled by the Transmission Network Service Provider, and hence reported by them. In the relatively few cases where Ergon Energy asset boundary at the TCP is inclusive of power transformers, the substation capacity will appear in the Zone or Bulk Supply Substations Forecasts tables. The forecast loads are given exclusive of any connected embedded generation.

The Distribution Feeder Limitations tables include the following information for each constrained distribution feeder:

• Ergon Energy region
• Distribution feeder name, ID & location
• Load exceedance after 2 yrs (MVA)
• Forecast season that exceedance occurs (Summer / Winter)
• Forecast year that exceedance occurs
• Forecast month/s that exceedance occurs
• Load reduction needed to delay the exceedance by 12 months (MW) (assumed power factor of 0.9)

Solutions
Suggested solutions, in order or preference, are included under the 'Solutions' tab.

Connection points for possible load reduction
In all cases, the connection point to apply load reduction would be downsteam of the substation exit feeder cable and/or first section of line.

Exclusions
Dedicated customer connection assets are excluded from the analysis.