FB_PMA_Harmonics_Period_3Ph
The function block FB_PMA_Harmonics_Period_3Ph calculates the current and voltage harmonics. In addition, the THD of the input values is calculated from the harmonics. In contrast to the function block FB_PMA_Harmonics_3Ph, the results refer to a configurable number of signal periods. The period value refers to the frequency specified at the start of the period at the input of the Call method. The statistical results refer to the entire runtime or the time at which the statistical results were last reset.
The input buffer is provided via the function block FB_PMA_Source_3Ph. This can include one or more signal periods or individual fragments of oversampling values.
Syntax
Definition:
FUNCTION BLOCK FB_PMA_PowerValues_Period_3Ph
VAR_INPUT
nOwnID : UDINT;
tTransferTimeout : LTIME := LTIME#500US;
stInitPars : ST_PMA_Harmonics_Period_InitPars;
END_VAR
VAR_OUTPUT
bError : BOOL;
ipResultMessage : I_TcMessage;
bNewResult : BOOL;
nCntResults : ULINT;
aTHD_U : ARRAY[0..2] OF LREAL;
aTHD_U_Min : ARRAY[0..2] OF LREAL;
aTHD_U_Max : ARRAY[0..2] OF LREAL;
aTHD_I : ARRAY[0..2] OF LREAL;
aTHD_I_Min : ARRAY[0..2] OF LREAL;
aTHD_I_Max : ARRAY[0..2] OF LREAL;
bValidStatistics : BOOL;
END_VAR
Inputs
The input parameters of this function block represent initialization parameters and must be assigned when declaring the function block instance (alternative: Init method). They may only be assigned once. A change at runtime is not possible.
Name | Type | Description |
|---|---|---|
nOwnID | UDINT | Identifies the function block instance with a unique ID. This must always be greater than zero. A proven approach is to define an enumeration for this purpose. |
tTransferTimeout | LTIME | Setting of the synchronous timeout for internal multi-array forwardings. See Parallel Processing in Transfer Tray. |
stInitPars | Function-block-specific structure with initialization parameters. The parameters must correlate to the above definition of the input and output buffers. |
Outputs
Name | Type | Description |
|---|---|---|
bError | BOOL | TRUE if an error occurs. |
ipResultMessage | I_TcMessage | The interface offers detailed information about the return value. |
bNewResult | BOOL | TRUE once new results have been calculated. |
nCntResults | ULINT | Count value is incremented with new output data. |
aTHD_U | ARRAY[0..2] OF LREAL | THD of the voltage. The output is in percent. |
aTHD_U_Min | ARRAY[0..2] OF LREAL | Smallest value of aTHD_U that has occurred. Can be reset via bResetStatistics of the Call method. |
aTHD_U_Max | ARRAY[0..2] OF LREAL | Largest value of aTHD_U that has occurred. Can be reset via bResetStatistics of the Call method. |
aTHD_I | ARRAY[0..2] OF LREAL | THD of the current. The output is in percent. |
aTHD_U_Min | ARRAY[0..2] OF LREAL | Smallest value of aTHD_U that has occurred. Can be reset via bResetStatistics of the Call method. |
aTHD_U_Max | ARRAY[0..2] OF LREAL | Largest value of aTHD_U that has occurred. Can be reset via bResetStatistics of the Call method. |
bValidStatistics | BOOL | TRUE if the Min and Max value calculation has been performed. These values are valid. |
Methods
Name | Description |
|---|---|
The method is called in each cycle to execute the calculations from the input buffer when new data is present. | |
Alternative to the function block initialization | |
As an alternative to the Call method, the method can be called in each cycle if no calculation is to take place. The incoming input buffer is then forwarded accordingly. | |
The current calculations are reset with the method. |
Sample
VAR CONSTANT
cOversamples : UDINT := 10;
cSourceInitPars: ST_PMA_Source_InitPars := (
nBufferLength := cOversamples);
cFrequencyInitPars : ST_PMA_Frequency_Period_InitPars := (
nBufferLength := cOversamples,
fSampleRate := cOversamples * 1000,
fMinFreq := 45.0,
fMaxFreq := 55.0,
nPeriods := 1,
nFilterOrder := 2,
fCutOff := 70.0,
eInputSelect := E_PMA_InputSelect.Voltage,
fMinInput := 200.0);
cPowerValuesInitPars : ST_PMA_PowerValues_Period_InitPars := (
nBufferLength := cOversamples,
fSampleRate := cOversamples * 1000,
fMinInputCurrent := 0.01,
nPeriods := 1);
END_VAR
VAR
aVoltage AT%I* : ARRAY[0..2] OF ARRAY [1..cOversamples] OF LREAL;
aCurrent AT%I* : ARRAY[0..2] OF ARRAY [1..cOversamples] OF LREAL;
fbSource : FB_PMA_Source_3Ph := (nOwnID := 1, aDestIDs := [2,3], stInitPars := cSourceInitPars);
fbFrequency : FB_PMA_Frequency_Period_3Ph := (nOwnID := 2, stInitPars := cFrequencyInitPars);
fbPowerValues : FB_PMA_PowerValues_Period_3Ph := (nOwnID := 3, stInitPars := cPowerValuesInitPars);
END_VAR
// Call source
fbSource.Call(
ADR(aVoltage[0]),
ADR(aVoltage[1]),
ADR(aVoltage[2]),
ADR(aCurrent[0]),
ADR(aCurrent[1]),
ADR(aCurrent[2]),
SIZEOF(aVoltage[0]),
0);
// Call algorithms
fbFrequency.Call(FALSE);
fbPowerValues.Call(fbFrequency.aFreq[0], FALSE, FALSE);
Requirements
Development environment | Target platform | PLC libraries to include |
|---|---|---|
TwinCAT v3.1.4024.0 | PC or CX (x86, x64) | Tc3_PowerMonitoring |