GE D90 Plus Instruction Manual page 434

AUTOMATION LOGIC
Automation logic programming example
426
8. Assigning the output of a math operator to a virtual analog terminates the equation.
The following automation logic programming example illustrates the implementation of a
voltage regulation scheme with line drop compensation. In this scheme, the
Plus
D90 measures the local end positive-sequence voltage and calculates the remote end
positive-sequence line voltage (the load center voltage) to compensate for the voltage
drop on the line.
In this example, the line positive-sequence impedance is 100.0 primary ohms at 80° and
the PT ratio is 1000:1. The difference between the remote end voltage and the setting
voltage (69.9 volts secondary = 69900 volts primary) is assigned to the virtual analog 1
value and named DELTA_V (note that all analog quantities in the automation logic are
primary values). The automation logic includes a voltage reduction command represented
by virtual input 1 and named V_REDUCT. If voltage reduction is enabled, then the setpoint
voltage is reduced by 5%.
The following logic calculates the magnitude and angle of I
to virtual analog 2 and virtual analog 3, respectively.
Figure 351: Magnitude and angle calculation logic for I
The following logic calculates the real and imaginary parts of the local positive-sequence
voltage and assigns these results to virtual analog 4 and virtual analog 5, respectively.
Figure 352: Real and imaginary component calculation logic for local voltage
Next, the real and imaginary components of the remote voltage is calculated and assigned
to virtual analog 6 and virtual analog 7, respectively.
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 8: AUTOMATION
× Z and assigns these results
1
× Z
1