ABB RED615 Technical Manual page 748

Section 9
Control functions
742
In this case, the circulating current can be calculated with the equation
(sin I sin
× −
φ φ
1 TR 1 2
I
=
ci
2
GUID-5898550F-0095-4173-91ED-4D5AFFC7B58D V2 EN
I Average primary value of the currents I_A, I_B and I_C measured by regulator 1
TR1
I Average primary value of the currents I_A, I_B and I_C measured by regulator 2
TR2
φ Phase angle between U_A and I_A in regulator 1
1
φ Phase angle between U_A and I_A in regulator 2
2
The circulation current can be read from the monitored data I_CIR.
Using the circulating current, the compensation term U
equation
− I Stability
ci
U = ×
ci
I 100
CT n _ 1
GUID-173A1FA0-8C07-4BA8-AAEB-62F95E10396C V2 EN
I Circulating current, primary value
ci
I Nominal primary current of the CT
CT_n1
Stability factor Stability setting (the recommended value depends on the loop impedance)
Using the circulating current, a compensation term U
Equation 93. The value of U
adding it to the Band center voltage U
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.
I )
×
TR 2
× U
n
, which can be positive or negative, is considered by
ci
(Equation
s
1YHT530004D05 D
can be calculated with the
ci
can be calculated using
ci
89). According to Figure 400
Technical Manual
(Equation 94)
and
615 series