GE D90 Plus Instruction Manual page 492

AUTOMATION LOGIC
Automation logic rules
Automation logic programming example
482
Figure 414: Typical automation logic display
When forming an automation logic equation, the sequence in the linear array of
parameters must follow these general rules:
1. There are two types of operators: logic operators and math operators.
2. Logic operands must precede the logic operator that uses the operands as inputs.
3. Logic operators have only one output. The output of an operator must be used to
create a virtual output if it is to be used as an input to two or more operators.
4. Assigning the output of a logic operator to a virtual output terminates the equation.
5. A timer operator (for example
1) can be used only once. If this rule is broken, a syntax error is declared.
Virt Op
6. Math operands must precede the math operator that uses the operands as inputs.
7. Math operators have only one output. The output of a math operator must be used to
create a virtual analog if it is to be used as an input to two or more operators.
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%.
1) or virtual output assignment (for example,
Aut Timer
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 8: AUTOMATION
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