Module: Ocpp::Rails::MeterAnomalyDetector

Defined in:
app/services/ocpp/rails/meter_anomaly_detector.rb

Overview

Checks Energy.Active.Import.Register readings against the session's series: the register must never decrease (rollover, meter swap) and must not jump implausibly between samples. Anomalous readings are flagged for review instead of silently entering energy accounting.

Constant Summary collapse

ENERGY_MEASURAND = 
"Energy.Active.Import.Register".freeze
REGISTER_DECREASE = 
"register_decrease".freeze
IMPLAUSIBLE_JUMP = 
"implausible_jump".freeze

Class Method Summary collapse

Class Method Details

.baseline_wh(session) ⇒ Object

Highest trustworthy register reading seen so far: meterStart plus all previously accepted (unflagged) energy samples, normalised to Wh.



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# File 'app/services/ocpp/rails/meter_anomaly_detector.rb', line 42

def self.baseline_wh(session)
  previous = session.meter_values.energy.where(flagged: false).maximum(
    Arel.sql("CASE WHEN unit = 'kWh' THEN value * 1000 ELSE value END")
  )
  [ previous, session.start_meter_value ].compact.max
end

.check(session:, measurand:, value:, unit:) ⇒ Object

Returns a flag reason string, or nil when the reading is plausible.



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# File 'app/services/ocpp/rails/meter_anomaly_detector.rb', line 14

def self.check(session:, measurand:, value:, unit:)
  return nil unless session && measurand == ENERGY_MEASURAND

  candidate = normalize_to_wh(value, unit)
  return nil unless candidate

  baseline = baseline_wh(session)
  return nil unless baseline

  max_jump = Ocpp::Rails.configuration.implausible_energy_jump_wh
  if candidate < baseline
    REGISTER_DECREASE
  elsif max_jump && candidate - baseline > max_jump
    IMPLAUSIBLE_JUMP
  end
end

.normalize_to_wh(value, unit) ⇒ Object 



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# File 'app/services/ocpp/rails/meter_anomaly_detector.rb', line 31

def self.normalize_to_wh(value, unit)
  return nil if value.nil?

  wh = BigDecimal(value.to_s)
  unit == "kWh" ? wh * 1000 : wh
rescue ArgumentError
  nil
end