Description

This model is the Woodward electric hydro governor model with PID control. The turbine model uses lookup tables to represent non-linearities in the flow rate versus gate position and the mechanical power versus flow rate during steady-state operation. The WEHGOV component was developed in line with the reference [1].

Mask and Parameters

WEHGOV Parameters

Expanding the "WEHGOV Block diagram" displays the block diagram in the parameters window.

Name	Description	Unit	Variable = {Possible Values}
R_PERM_GATE	Permanent droop gain on gate position in per unit on generator MVA base	pu	-
R_PERM_PE	Permanent droop gain on electrical power in per unit on generator MVA base	pu	-
TPE	Measured electrical power filter time constant	s	-
KP	Proportional controller gain	-	-
KI	Integral controller gain	-	-
KD	Derivative controller gain	-	-
TD	Derivative controller time constant	s	If TD < 0.004, then TD = 0.004
TP	Pilot valve servo time constant	s	If TP < 0.004, then TP = 0.004
TDV	Distribution valve servo time constant	s	If TDV < 0.004, then TDV = 0.004
TG	Gate servo time constant	s	If TG < 0.004, then TG = 0.004
GTMXOP	Maximum distribution valve opening velocity	pu	-
GTMXCL	Maximum distribution valve closing velocity	pu	-
GMAX	Maximum gate/controller limit	pu	-
GMIN	Minimum gate/controller limit	pu	-
DBAND	Deadband limit on the PID input	-	-
DPV	Pilot valve limit modifier	pu	-
DICN	Integral controller limit modifier	pu	-
Feedback_SW	Feedback signal selection 0 = Feedback is gate position and electrical power, 1 = Feedback is the PID output	--	[0,1]

Turbine Dynamics Parameters

Expanding the "WEHGOV Turbine Dynamics" displays the block diagram in the parameters window.

Name	Description	Unit	Hard coded values
DTURB	Turbine damping factor in per unit on generator MVA base	pu	-
TW	Water inertia time constant	s	If TW < 0.004, then TW = 0.004
GATE = [GATE1 to GATE5]	Gate position curve points on a piecewise linear curve	pu	GATE1 - GATE5 in ascending order of values
FLOW_G = [FLOW_G1 to FLOW_G5]	Water flow rate curve points on a piecewise linear curve	pu	FLOW_G1 - FLOW_G5 in ascending order of values
FLOW_P = [FLOW_P1 to FLOW_P10]	Water flow rate curve points on a piecewise linear curve	pu	FLOW_P1 - FLOW_P10 in ascending order of values
PMECH = [PMECH1 to PMECH10]	Per unit mechanical power curve points on machine MVA rating. Curve points are on a piecewise linear curve	pu	PMECH1 - PMECH10 in in ascending order of values

Initial Values Tab

Name	Description	Unit	Variable = {Possible Values}
Pm0	Initial mechanical power output	pu	--
w0	Speed reference	pu	--

The speed reference can be set manually, by entering a numerical value. It can also be set automatically based on load flow calculations, by entering a referenced synchronous machine variable. Machine variables can be found in the machine netlist. For instance, if the name of the synchronous machine on which the governor/turbine is connected is “SM1”, then the speed reference should be inserted as “=SM1.wo” if a thermal machine or a hydraulic machine is used, and as "=SM1.Wm_Init" if a pu standard or pu fundamental machine is used.

The same goes for initial power output of the machine Pm0. Pm0 shall be set as =SM1.Peo/SM1.BaseMVA, if a thermal machine or a hydraulic machine is used, and as "=SM1.lfP/1e6/SM1.sBase" if a pu standard or a pu fundamental machine is used, where Peo and IfP are the initial power outputs of the machines, respectively.

The HYPERSIM simulation option “Set Initial Conditions” must be checked for the automatic initialization to work properly.

Inputs and Outputs and Additional Signals Available for Monitoring

Inputs

I/O name	Description	Unit
w	Machine actual speed	pu
VAR	External control reference	pu
Pe	Measured electrical power	pu

Outputs

I/O name	Description	Unit
Pm	Mechanical power output	Output

References

[1] P. Kundur, Power System Stability and Control, New York:McGraw-Hill, 1994.

[2] PSS®E 34.2.0 Model Library. NY, USA: Siemens Industry, Inc., 2017.

[3] T. Tshibungu and J. Mahseredjian, Exciters and Governors: Governor-Turbine HYGOV. EMTP-EMTPWorks, 2016.