In this article:
Overview
This calculation combines all relevant information available to create a “smart event” for snow. The calculation runs once overnight on PV sites. It requires day of and day prior historical data, with the caveat that Inverter Classifier is an input, which needs at least 3 months of historical data to populate a given day’s classification and probability.
Calculation Logic
Open Logic
Inverter.FinalClassification.Calculated = SNOW | All inverters have low PerformanceIndex | Inverter.Snow.Calculated (classifier probability) from inverters with Inverter.FinalClassification = SNOW | Precipitation present AND low ambient temperature | Open snow event? |
|---|---|---|---|---|
> half inverters on site | - | high | - | open |
> half inverters on site | - | medium OR variable OR missing | yes | open |
> half inverters on site | - | medium OR variable OR missing | no OR missing | no |
> half inverters on site | - | low | - | no |
missing | no OR missing | - | - | no |
missing | yes | high | - | open |
missing | yes | medium OR variable OR missing | yes | open |
missing | yes | medium OR variable OR missing | no OR missing | no |
missing | yes | low | - | no |
<= half inverters on site | - | - | - | no |
Close Logic
Inverter.FinalClassification.Calculated = SNOW | All inverters have low PerformanceIndex | Inverter.Snow.Calculated (classifier probability) from inverters with Inverter.FinalClassification = SNOW | Precipitation present AND low ambient temperature | Close snow event? |
|---|---|---|---|---|
> half inverters on site | - | high OR medium OR variable | - | no |
> half inverters on site | - | low | - | close |
missing | no | - | - | close |
missing | missing | - | yes | no |
missing | missing | - | no OR missing | close |
missing | yes | high OR medium OR variable | - | no |
missing | yes | low | - | close |
<= half inverters on site | - | - | - | close |
Glossary
Phrase | Meaning |
|---|---|
missing PI | Filter Inverter.PerformanceIndex.Calculated by Inverter.ActivePower.ValidationFlag = VALID and Site.SunHeightAngle.Calculated > 0. If availability < |
all inverters have low PI | Calculate mean PI per inverter for morning (0 <= Site.SunAzimuthAngle.Calculated <= 180) and afternoon (180 <= Site.SunAzimuthAngle.Calculated <= 360) Evaluate if all inverters have mean < |
Inverter.Snow.Calculated is high | Inverter.Snow.Calculated >= |
Inverter.Snow.Calculated is medium | If not high, Inverter.Snow.Calculated >= |
Inverter.Snow.Calculated is variable | If not high, standard deviation of all inverters' Inverter.Snow.Calculated >= |
Inverter.Snow.Calculated low | If not high nor medium nor variable. |
precipitation present | SUM(SatelliteWeatherStation.SolidPrecipitation.Mean) > |
ambient temperature low | When precipitation > 0, MEAN(Site.AmbientTemperature.Final) < |
Inputs and Outputs
Inputs
Signals
Segment Apcode | Mloc Apcode | CalcType | CalcPeriod | MType | Notes |
|---|---|---|---|---|---|
Site | AmbientTemperature | Final | siteTR | Temperature | day prior and of |
Site | AmbientTemperature | CascadeFlag | siteTR | Temperature | day prior and of |
Site | SunAzimuthAngle | Calculated | siteTR | Angle | day of |
Site | SunHeightAngle | Calculated | siteTR | Angle | day of |
Site | SnowEventFlag | Calculated | siteTR | Flag | day prior; need to know whether an event is already open or not |
Inverter | ActivePower | ValidationFlag | siteTR | Power | day of |
Inverter | FinalClassification | Calculated | 1D | Inverter Classifier | day of |
Inverter | Snow | Calculated | 1D | Inverter Classifier | day of; classification probability of snow |
Inverter | PerformanceIndex | Calculated | siteTR | Percent | day of |
SatelliteWeatherStation | SolidPrecipitation | Mean | siteTR | Precipitation | day prior and of |
Configuration Parameters
Parameter | Value | Notes |
|---|---|---|
| 5.0 | While there is precipitation, the mean of the ambient temperature must be below this threshold to be considered low temperature. |
| 0.25 | Performance Index must be available during the day for at least this proportion of time |
| 90.0 | The given time is considered to have low Performance Index (PI) if the mean of PIs from all inverters is less than this threshold. |
| 3.0 | The sum of precipitation must be above this threshold to be considered precipitation occurred. |
| HIGH_THRESHOLD: 80.0 | Thresholds that classify the snow probability as high, medium, variable, or low. |
Outputs
Signals
Segment Apcode | Mloc Apcode | CalcType | CalcPeriod | MType | Unit |
|---|---|---|---|---|---|
Site | SnowEventFlag | Calculated | siteTR | Flag | - |
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