Voltage Vector Shift Protection; Application Notes; Voltage Vector Shift Calculations; Figure 115: Voltage Vector Shift Logic - GE MiCOM P40 Agile Technical Manual

P14D
10

VOLTAGE VECTOR SHIFT PROTECTION

The P14D has a single stage Voltage Vector Shift protection element. This element measures the change in voltage
angle over successive power system half-cycles. The element operates by measuring the time between zero
crossings on the voltage waveforms. A measurement is taken every half cycle for each phase voltage. Over a
power system cycle this produces 6 results, a trip is issued if 5 of the 6 calculations for the last power system cycle
are above the set threshold. Checking all three phases makes the element less susceptible to incorrect operation
due to harmonic distortion or interference in the measured voltage waveform.
The DDB signal, V Shift Trip is used to indicate that the element has operated. The state of V Shift Trip can also be
programmed to be viewed in the Monitor Bit x cells of the COMMISSION TESTS column.
V Shift Angle
Freq Not Found
V<1 Voltage Set

Figure 115: Voltage vector shift logic

10.1

APPLICATION NOTES

10.2

VOLTAGE VECTOR SHIFT CALCULATIONS

The P14D has a single stage Voltage Vector Shift protection element. This element measures the change in voltage
angle over successive power system half-cycles. The element operates by measuring the time between zero
crossings on the voltage waveforms. A measurement is taken every half cycle for each phase voltage. Over a
power system cycle, this produces 6 results, a trip is issued if 5 of the 6 calculations for the last power system cycle
are above the set threshold. Checking all three phases makes the element less susceptible to incorrect operation
due to harmonic distortion or interference in the measured voltage waveform.
An expression for a sinusoidal mains voltage waveform is generally given by the following:
V = Vp sin (wt) or V = Vp sin q(t)
Where:
q(t) = wt = 2pft
If the frequency is changing at constant rate Rf from a frequency fo then the variation in the angle (t) is given by:
q(t) = 2pòf dt,
which gives:
q(t) = 2p (f
t + t R t/2),
o f
P14D-TM-EN-8
V Angle
VA
VB
VC
Chapter 10 - Voltage Protection Functions
& V Shift Trip
&
V00826
211