Terms
In the mathematical sense, a “term” allows you to define custom data points at the system level using your own formula, which is evaluated for the variables used for every available timestamp. The Term editor in VCOM allows you to process measured data from your system and generate key performance indicators. Terms are integral to charts, simulations, KPIs, evaluations, and certain portlets. For example, you can use terms to calculate the average for several sensors or to define the parameters to determine the total energy (E_Z_EVU).
Term editor
Item | Name | Details |
---|---|---|
1 | Term | Create new term |
2 | Recalculation of terms | Re-calculate all terms within a selected time period. Overwrites previous values. |
3 | Designation | The designation of a term is a user-friendly name and will later be visible in graphs and reports. |
4 | Abbreviation | The abbreviation of a term defines how the results of this term can be referenced in other terms and through the VCOM API. If possible, use the defined abbreviations. See Terms abbreviations with a special meaning |
5 | (Aggregation) Type | The Type field describes how the values that this term yields should be aggregated. Currently, there are two options:
Important: If the unit |
6 | Unit | The unit field selects the unit to be displayed in charts and reports. |
7 | Formula | Formulas consist of the following. See also Formulas
Eye icon: Preview of formula results for the selected day |
8 | Measurement overview | Overview of the available data sources (=variables) and the corresponding terms for your system |
Create terms: general workflow
Prerequisites
None
Steps
Go to System configuration (Wrench icon) > Calculations > Terms > Term editor > Term.
View data sources and select relevant devices (Measurement overview).
Enter designation, abbreviation, type, unit, formula.
The terms can then be applied throughout VCOM, for example in the Power flow portlet and Charts.
Abbreviations with a special meaning
Abbreviation | Required unit | Use in VCOM | Description |
---|---|---|---|
E_Z_EVU | kWh | Simulation, alarms, charts, various KPIs | Energy generated per interval for the whole system |
E_Z_PV(1..x) | kWh | Meter comparison chart | |
G_M0 | W/m² | Simulation, charts, various KPIs | Weighted irradiance on the module plane |
G_H0 | W/m² | Evaluation | Weighed irradiance on the horizontal plane |
G_Mx (x = 1..99) | W/m² | Simulation | Other irradiance measurements on the module plane |
G_Hx (x = 1..99) | W/m² | Evaluation | Other irradiance measurements on the horizontal plane |
E_Z_PVx (x= 1..99) | kWh | Energy comparison chart, evaluation | |
T_M0 | °C | KPIs | Module temperature per interval for the whole system |
T_U(0..x) | °C | Ambient temperature | |
M_AC_E_EXP | kWh | Self-consumption chart | Energy export |
M_AC_E_IMP | kWh | Self-consumption chart | Energy import |
M_AC_E_OWN | kWh | Self-consumption chart | Energy self-consumption |
PF_P_GEN | W | Power flow portlet | PV power |
PF_P_GRID | W | Power flow portlet | Import / export power |
PF_P_CON | W | Power flow portlet | Consumption power |
PF_P_BAT | W | Power flow portlet | Battery power |
W_V(0..x) | m/s | Wind speed | |
W_D(0..x) | ° | Wind direction |
Formulas
Variables and data source
You must specify at least one variable for each formula otherwise nothing will be calculated. VCOM provides you with an overview of the available data sources (=variables) and the corresponding terms for your system. For this, select Measurement overview (Question mark icon) while editing a term. In general, all variables start and end with an apostrophe ('
). Any configured device can be selected separately via the dropdown menu. If no device is selected, the sum of all devices will be taken.
The result of the term is not tied to a specific device; even if it uses the values from one device, it applies to the entire system and is not associated with any particular device.
For the sake of simplicity, the examples used below will not use variables and use NULL
to represent a null-value returned by a variable or calculation.
Numbers
In addition to variables, numbers can be used. Both,
and .
can be used as a decimal separator. Thousands separators and scientific notation are not supported.
Operators
To combine multiple variables (and numbers), various operators are available. In general, all operators will yield null
if any of the operands are null
, the only exception of that rule being ??
. The precedence describes the order of calculation, with higher precedence evaluated before lower precedence
Functions
In addition to operators, functions can greatly reduce the complexity of formulas. Functions calls consist of a function identifier, followed by a list of parameters (separated by ;
) in parenthesis ( )
. Calling functions with fewer/more parameters than required is an error.
Simple functions
Complex functions
Example
In the example below, the datapoint E_Z_EVU is defined as the energy sum of the inverters.