In this case, the circulating current can be calculated with the equation
I
I I
ci
TR TR
=
× − ×(sin sin )
φ φ
1 1 2 2
2
GUID-5898550F-0095-4173-91ED-4D5AFFC7B58D V2 EN (Equation 94)
I
TR1
Average primary value of the currents I_A, I_B and I_C measured by regulator 1
I
TR2
Average primary value of the currents I_A, I_B and I_C measured by regulator 2
φ
1
Phase angle between U_A and I_A in regulator 1
φ
2
Phase angle between U_A and I_A in regulator 2
The circulation current can be read from the monitored data I_CIR.
Using the circulating current, the compensation term U
ci
can be calculated with the
equation
U
I
I
U
ci
ci
CT n
n
=
−
× ×
_ 1
100
Stability
GUID-173A1FA0-8C07-4BA8-AAEB-62F95E10396C V2 EN
I
ci
Circulating current, primary value
I
CT_n1
Nominal primary current of the CT
Stability factor
Stability setting (the recommended value depends on the loop impedance)
Using the circulating current, a compensation term U
ci
can be calculated using
Equation 93. The value of U
ci
, which can be positive or negative, is considered by
adding it to the Band center voltage U
s
(
Equation 89). According to Figure 400 and
Equation 94, the phasor information from the other IEDs is needed.
Parallel unit detection and the MCC mode
The network connection status information is essential for the MCC operation
mode. The status FALSE needs to be connected to the CON_STATUS input to
ensure a proper operation of the MCC calculation if the transformer is disconnected
but OLATCC remains in the MCC mode. This way the disconnected transformer is
excluded from the circulating current calculations.
The CON_STATUS input is used to identify if a certain transformer controller is
able to send the current information to other transformer controllers for circulating
current minimization purposes. As a result, this input has effect only in the MCC or
Manual acting operation modes. In these modes, if CON_STATUS is TRUE, the
information transmission is started. The circulating current information receiving is
allowed only in the MCC acting operation mode when CON_STATUS is TRUE.
PAR_UNIT_MCC can be seen in the monitored data view.
Section 9 1YHT530004D05 D
Control functions
742 615 series
Technical Manual
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