Feeder and transformer energy balance
Comparing the energy measured entering each feeder or distribution transformer with the sum of the customer meters it supplies, so revenue protection teams work in the network areas where unbilled energy is concentrated.
Part of the recommended approachTechnique: Rules Engine
An energy balance compares what goes into a part of the network with what comes out through customers’ meters.
The energy measured at a feeder or distribution transformer, minus the expected technical losses, should roughly equal the sum of its customers’ readings, and a persistent gap is energy being consumed without being billed.
A widely cited study uses this as the first stage of detection, shortlisting transformers with a high likelihood of theft before examining the consumption of individual customers on them.
Revenue protection managers use the balance to decide where to campaign, and then either inspect every premises in a small high-loss area or rank the premises in a larger one.
This is the right tool wherever feeders and transformers are metered and illegal connections or bypasses are suspected, since those leave no trace in the customer’s own meter.
It is the wrong tool where the connectivity model is unreliable, and fixing the model has to come first.
Strengths for this problem
- Measures loss directly, so it finds illegal connections and bypassed meters that record nothing at the customer's meter.
- Shows where losses are concentrated across the network, which sets the size of the problem in each area and stops inspectors returning to the same neighbourhoods by habit.
- The calculation is simple arithmetic that engineers, managers, and the regulator can check.
Limitations for this problem
- Points to an area, not a premises, so it still needs inspections or a ranked list to find which customers are responsible.
- Needs a meter on each feeder or transformer and readings taken over the same period as the customer meters.
- Breaks when customers are recorded against the wrong transformer, because the loss moves with them.
- Has to separate technical losses, which rise with load and cable length, from non-technical losses.
Data needed
- Energy measured at each feeder and distribution transformer, over the same intervals as customer readings.
- A customer-to-transformer and customer-to-feeder connectivity model, checked against the field.
- Customer meter readings for every premises on the transformer, with estimated reads flagged.
- An estimate of technical losses for each feeder or transformer from its length, load, and equipment.
How it is measured
- Non-technical loss per feeder and transformer, and its trend after each campaign.
- Share of total network losses located to a specific feeder or transformer.
- Hit rate of inspections in high-loss areas compared with inspections elsewhere.
Pitfalls
- Trusting a connectivity model that has not been checked, so a loss is assigned to the wrong transformer and inspectors visit the wrong customers.
- Comparing a transformer reading with customer bills that include estimated reads, which creates or hides a loss.
- Calling the whole gap theft without subtracting an estimate of technical losses.
Human oversight
Network engineers own the feeder and transformer metering and the connectivity model, and confirm in the field any customer whose connection is in doubt. Revenue protection managers decide which areas to campaign in. Inspectors confirm any irregularity at a premises before anything is done about it.