Page Content

1 Mask and Parameters
2 Inputs, Outputs, and Signals Available for Monitoring
- 2.1 Inputs
- 2.2 Outputs
- 2.3 Description
- 2.4 Constant Power Factor (CPF)
- 2.5 Voltage- Reactive Power (Volt-VAR)
- 2.6 Active Power- Reactive Power (Watt-VAR or PQ)
- 2.7 Constant Reactive Power (Cons. Q)
- 2.8 Voltage -Active Power (Volt-Watt)
- 2.9 Frequency -Watt (Droop)
3 Limitations
4 References
5 Intellectual Property Disclaimer

The secondary control block contains the logic to implement grid support functions (GSF) considering the specifications from IEEE Std 1547-2018 [1]. Therefore, it can be applicable to implement grid support functions from other grid codes that use similar specifications. It generates the active and reactive power references used by the primary control loops. Typically, the active power reference is used as a limiting value for active power injection. The secondary control block allows the user to select which grid support functions are activated and define their respective parameters. The GSF are separated into three categories: Voltage Support with Reactive Power Control, Voltage Support with Active Power Control, and Frequency Support with Active Power Control. This structure allows to have multiple grid support functions operating simultaneously while also ensuring their mutual exclusivity.

Mask and Parameters

The Secondary Control block contains the following configuration tabs:

General
Voltage Support with Reactive Power Control
Voltage support with Active Power Control
Frequency Support with Active Power Control

General Tab

Name	Description		Unit

Name	Description		Unit
Nominal Frequency	Nominal grid frequency		Hz
Minimum Active Power	Minimum active power output capacity		pu
Voltage Support with Reactive Power Control	Constant Power Factor (CPF)	Specify this option to maintain a constant power factor at the point of coupling	-
	Voltage-Reactive Power (Volt-VAR)	Specify this function to output reactive power reference as a function of the measured point of coupling voltage	-
	Active power- Reactive power (Watt-VAR or PQ)	Specify this function to output reactive power reference as a function of the measured active power output.	-
	Constant reactive power	Specify this function to output the desired reactive power reference.	-
Voltage Support with Active Power Control	None	No function is activated	-
Voltage Support with Active Power Control	Voltage – Active Power (Volt-Watt)	Specify this function to output active power reference as a function of the measured point of coupling voltage.	-
Frequency Support with Active Power Control	None	No function is activated	-
Frequency Support with Active Power Control	Frequency -Watt (Droop)	Specify this function to output active power reference as a function of the measured point of coupling frequency	-
Select Power Priority	Reactive Power Priority	When selected, active power output (Pr) is limited to keep apparent power less than or equal to 1 pu. Accordingly, active power will be curtailed for the required reactive power	-
Select Power Priority	Active Power Priority	When selected, reactive power output (Qr) is limited to keep apparent power less than or equal to 1 pu	-
Sampling Time	Specify the timestep for solving equations inside the secondary block		s
Initialization Freeze Time	The active power output (Pr) and the reactive power output (Qr) are 1 pu and 0 pu, respectively, during this interval of time directly after starting the simulation.		s

Voltage Support with Reactive Power Control Tab

The subtab and its corresponding parameters displayed on this tab vary depending on the choice made for 'Voltage Support with Reactive Power Control'. Four different subtabs and their parameters appear based on the choice of 'Voltage Support with Reactive Power Control'.

When 'Voltage Support with Reactive Power Control' is configured as 'Constant Power Factor (CPF),' the subtab labeled 'Constant Power Factor' and its associated parameters are shown.

Name	Description	Unit

Name	Description	Unit
Constant Power Factor	Specify the constant power factor setpoint to be set as either Under-Excited (VAR Absorption) or Over-Excited (VAR Injection)	-
PF Limits Injecting [Min Max]	Specify the minimum and maximum power factor limits during over-excited mode (This parameter is activated when the Over-Excited (VAR Absorption) mode is chosen for Constant Power Factor and deactivated when the Over-Excited (VAR Absorption) mode is selected for Constant Power Factor).	-
Pf Injecting	Specify the power factor injection reference (This parameter is activated when the Over-Excited (VAR Absorption) mode is chosen for Constant Power Factor and deactivated when the Over-Excited (VAR Absorption) mode is selected for Constant Power Factor).	-
Pf Limits Absorbing [Min Max]	Specify the minimum and maximum power factor limits during under-excited mode (This parameter is deactivated when the Over-Excited (VAR Absorption) mode is chosen for Constant Power Factor and activated when the Over-Excited (VAR Absorption) mode is selected for Constant Power Factor).	-
Pf Absorbing	Specify the power factor absorption reference (This parameter is deactivated when the Over-Excited (VAR Absorption) mode is chosen for Constant Power Factor and activated when the Over-Excited (VAR Absorption) mode is selected for Constant Power Factor).	-
Open Loop Response Time	The desired open-loop settling time of this function.	Sec

When 'Voltage Support with Reactive Power Control' is configured as 'Voltage-Reactive Power (Volt-Var),' the subtab labeled 'Volt - VAR' and its associated parameters are shown.

Name	Description	Unit

Name	Description	Unit
Reference Voltage	Specify the voltage reference setpoint (center of the Volt-VAR curve)	pu
Voltage Points	Specify the voltage points of the Volt-VAR curve	pu
Reactive Power Points	Specify the reactive power points of the Volt-VAR curve	pu
Enable Autonomous Vref Adjustment	When enabled, the voltage reference (center of the Volt-VAR curve) dynamically changes to the average value of the grid voltage	-
Vref Adjustment Time Constant	Specify the voltage reference filter time constant. Vref is defined as the moving average of the measured positive sequence voltage at the point of coupling over a user-defined time window. (This parameter is activated when the Enable Autonomous Vref Adjustment is enabled).	s
Open Loop Response Time	Desired open-loop settling time for the transient response of this function	s