ABB RED615 Technical Manual page 746

Section 9
Control functions
740
φ
1
I
LOAD
GUID-2B71B160-FB76-4BE0-952F-75F42220401F V2 EN
Figure 399: The expected phase angle of the load supplied by the transformers
operating in parallel is entered as a setting value φ
The regulators calculate the circulating current with the equation
= − ×
I (sin tan
ϕ ϕ
1
ci Load
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I Average of the currents I_A, I_B and I_C
TR1
φ Phase angle between U_A and I_A
1
φ The set Load phase angle of the load current
Load
In the negative reactance method, the circulating current is minimized by changing
the control voltage according to the measured circulating current. The regulator
calculates the circulating current compensation term U
− I Stability
ci
U = × × U
ci n
I 100
n
GUID-2A7864D3-D59F-47F9-84FD-B3F2C15178EB V1 EN
I Circulating current
ci
Stability Stability setting (the recommended value depends on the loop impedance)
If the transformers operating in parallel have different rated currents, the value of
the Stability factor setting of the regulator should be proportional to the rated
currents, that is, the higher the rated current, the higher the Stability factor setting
value.
φ
LOAD
I
LOAD
I
LOAD
Ici = circulating
I
TR1
= I x │cos(φ )│/cos(φ
TR1 1
×
cos ) I
ϕ
1 1
TR
1YHT530004D05 D
U_A
x sin(φ )
LOAD
I
TR1
current
)
LOAD
Load
using the equation
ci
Technical Manual
x sin(φ )
1
(Equation 92)
(Equation 93)
615 series