Generator Information: Power and Voltage Control

 

The Power Control grouping fields are used to show/change the values associated with the real power output of the generator.

 

MW Output

Current real power output of the generator.

MW Setpoint

If a generator is presently online this will show the same value as the MW Output. If the generator either has a status of OPEN or if the bus is disconnected, then MW Output will show 0.00, but the MW Setpoint will show the value of MW that is stored with generator and if the generator does get reconnected that is the MW it will be at.

Minimum and Maximum MW Output

Minimum and maximum real power output limits for the generator. Simulator will not let the MW output go below its minimum value or above its maximum value if the Enforce MW Limits option is exercised.

Available for AGC

Determines whether or not the generator is available for automatic generation control (AGC). Normally this box should be checked. However, there are times when you would like to control the generator output manually (such as if you are using the generator to remove a line limit violation), in which case you should leave this box unchecked. A generator is also placed on "manual" control any time you manually change its output. You could then place the generator back on AGC control by using this dialog.

Enforce MW Limits

If checked, the minimum and maximum MW limits are enforced for the generator, provided the Enforce Generator MW Limits field is also checked on the Limits Tab of the Simulator Options Dialog. If this box is checked and a generator is violating a real power limit, the generator's MW output is immediately changed.

Participation Factor

The participation factor is used to determine how the real power output of the generator changes in response to demand when the generator is available for AGC and the area is on participation factor control. When you open a case using the PTI Raw Data Format this field is initialized to the per unit MVA rating of the generator, since participation factor information is not stored in the PTI format.

Loss Sensitivity

Shows how the losses for an area will change for an incremental increase in the generation at the bus. This information is useful in determining the economic dispatch for the generation. The implicit assumption in calculating this field's value is that the incremental change in generation will be absorbed by the system "slack bus." This field cannot be changed.

 

The Voltage Control grouping is used to show/change values associated with controlling the voltage/reactive power output of the generator.

 

Mvar Output

Current reactive power output of the generator. You can manually change this value only if Available for AVR is not checked.

Min and Max Mvar Output

Specify the minimum and maximum allowable reactive power output of the generator.

Available for AVR

Designates whether or not the generator is available for automatic voltage regulation (AVR). When the AVR field is checked, the generator will automatically change its reactive power output to maintain the desired terminal voltage within the specified reactive power range. If a reactive limit is reached, the generator will no longer be able to maintain its voltage at the setpoint value, and its reactive power will then be held constant at the limit value.

Use Capability Curve

If checked, the generator's reactive power limits are specified using a reactive capability curve that prescribes the dependence of the generator's reactive power limits on its real power output. Otherwise, the fixed values given in the Min Mvar Output and Max Mvar Output fields are used. The generator reactive capability can be defined using the table that appears at the bottom of the dialog. Please see Generator Reactive Power Capability Curve for details.

Regulated Bus Number

Number of the bus whose voltage the generator is regulating. This is usually, but not always, the generator's terminal bus. Multiple generators can regulate the same remote bus, but the regulated bus must not be another generator bus. If the generator is at a slack bus, it must regulate its own terminal voltage. Select Solution Details > Remotely Regulated Buses from the Model Explorer to view the Remotely Regulated Bus Records Dialog , which identifies all buses that are being remotely regulated. Also see topic explaining the theory of Remote Voltage Regulation.

Actual Reg. Bus Voltage

Shows the actual per unit voltage at the regulated bus. If the generator is on AVR and has not reached a reactive power limit, the actual regulated bus voltage should be equal to the desired regulated bus voltage. This field cannot be changed.

SetPoint Voltage

Specifies the desired per unit voltage for the generator at the regulated bus. The regulated bus need not be the terminal bus of the generator.

SetPoint Voltage Tol Added in Version 21

Specifies the tolerance of the desired per unit voltage for the generator at the regulated bus. This then utilized Voltage Setpoint tolerance algorithm for the power flow equations.

Remote Reg %

This field is used when a number of generators are regulating the same bus, whether the bus is remote or the terminal bus of the generator, to determine how much reactive power this generator provides to maintain the regulated bus voltage. The power flow solution option for Mvar Sharing Between Generators determines how this percentage is used.

Line Drop Compensation

Use LDC can be set to NO, YES, or PostCTG to specify when to use the Line Drop compensation in the voltage control algorithm. When using line drop compensation, the value of Xcomp and Rcomp will be used by the power flow solution. The values on this dialog are given in per unit on the System MVA BAse.

Voltage Droop Control

Specify the name of the VoltageDroopControl object to which the generator is assigned. This is blank by default. When specified the generator will participate in Voltage Droop Control with Deadband.

Wind Control Mode and Power Factor 

The Wind Control Mode effects how generator Mvar limits are treated and can be set to either None, Boundary Power Factor , Constant Power Factoror Follow Min Mvar Capability Curve.

When the mode is None, then the generator behaves using the standard settings of the Min and Max Mvar Output and Capability Curve described above.

For Follow Min Mvar Capability Curve mode, the Mvar output of the generator is determined by a lookup from the capability curve's Min Mvar value. Essentially the Max Mvar Output and the Min Mvar Output are then made equal to this value. This provides the ability to make a generator's Mvar output any piece-wise linear function of the MW output.

For both the Boundary and Constant modes, the Mvar limit magnitudes are determined from the actual MW Output and the Wind Control Mode Power Factor value.

Magnitude = MWOutput * tan(arccos(Power Factor))

For Boundary mode, the Max Mvar Output is positive and the Min Mvar Output is negative. This provides a boundary under which the Mvar must operate.

For Constant mode, Max Mvar Output and the Min Mvar Output are made the same with a positive Wind Control Mode Power Factor meaning the limits have the same sign as the actual MW Output, and a negative Wind Control Mode Power Factor meaning the limits are the opposite sign as the actual MW Output, thus the Mvar output is a function of MW Output and Power Factor.