ABB Remote I/O RIO600 - Page 132

Y
I
U
Y j Y G
stab
CPS
CPS
stab stab
osta0
1
0
1
0
1
0
1
0
1
3
=
⋅
−
=




+




=Re Im
bb ostab
j B
1 1
+ ⋅
GUID-213A397D-2A9F-493E-A0FC-F7242CF11F8C V1 EN (Equation 16)
Y
stab
0
1
Stabilized fundamental frequency admittance estimate, which is result from fundamental
frequency admittance calculation utilizing the Cumulative Phasor Summing (CPS) technique
I
CPS
0
1
Fundamental frequency zero-sequence current phasor calculated utilizing the Cumulative
Phasor Summing (CPS) technique
U
CPS
0
1
Fundamental frequency zero-sequence votlage phasor calculated utilizing the Cumulative
Phasor Summing (CPS) technique
G
ostab
1
Real part of stabilized fundamental frequency conductance estimate
B
ostab
1
Imaginary part of stabilized fundamental frequency susceptance estimate
I G j B U I j I
stab
ostab ostab baseres oCosstab oSinsta0
1 1 1 1
= + ⋅
( )
⋅ = + ⋅
bb
1
GUID-789BBC8B-72F7-421B-A758-1F29A77FC2DC V1 EN (Equation 17)
G
ostab
1
Real part of stabilized fundamental frequency conductance estimate
B
ostab
1
Imaginary part of stabilized fundamental frequency susceptance estimate
I
stab
0
1
Stabilized fundamental frequency residual current estimate, which is obtained (after
conversion) from the corresponding admittance value by multiplying it with the system
nominal phase-to-earth voltage value
I
oCosstab
1
Real part of stabilized fundamental frequency residual current estimate
I
oSinstab
1
Imaginary part of stabilized fundamental frequency residual current estimate
The main advantage of the filtering method is that due to the admittance calculation,
the resulting current value does not depend on the value of fault resistance, that is, the
estimated current magnitude equals the value that would be measured during a solid
earth fault (Rf = 0 Ω). Another advantage of the algorithm is that it is capable of
estimating the correct current magnitude during intermittent earth faults.
The setting Min Forward Operate current defines the minimum operate current if the
operation direction is set to “Forward”. The Min Reverse Operate current setting
defines the minimum operate current if the operation direction is set to “Reverse”.
With the previously described special filtering technique, the settings Min Forward
Operate current and Min Reverse Operate current are based on fundamental
frequency residual current values.
Section 6 1MRS757488 H
Commissioning
124 RIO600
Installation and Commissioning Manual