IEEE Governor Models

This page documents the IEEE-standard turbine-governor models available in RAMSES, all using the tor_ prefix. These models implement standardised transfer-function blocks for diesel, gas-turbine, steam-turbine, hydraulic, and simplified ENTSO-E governors.

Usage in Dynamic Data Files

Governor/torque models in RAMSES are defined as sub-records within a SYNC_MACH block using the TOR keyword, followed by the model name and its parameters. They are not standalone records. The TOR line appears after the EXC (exciter) line, and the ; at the end closes the entire SYNC_MACH block.

SYNC_MACH name bus FP FQ P Q SNOM Pnom H D IBRATIO
                    XT  Xl  Xd  X'd  X"d  Xq  X'q  X"q  m  n  Ra  T'do  T"do  T'qo  T"qo
              EXC model_name  param1  param2  ...
              TOR model_name  param1  param2  ... ;

RAMSES adds the tor_ prefix to the model name automatically, so both DEGOV1 and tor_DEGOV1 resolve to the same model. The IEEE governor names are:

Data-file name	With explicit prefix	Implemented by	Available since
DEGOV1	tor_DEGOV1	tor_DEGOV1	3.40
ENTSOE_simp	tor_ENTSOE_simp	tor_ENTSOE_simp	3.40
GAST	tor_GAST	tor_GAST	3.50
TGOV1	tor_TGOV1	tor_TGOV1D	3.50
HYGOV	tor_HYGOV	tor_hygov	3.50

Only the first two columns are valid in a data file. The third column is the name of the Fortran subroutine, which you need only when registering the model in URAMSES.

GAST, TGOV1 and HYGOV require RAMSES 3.50 or later

Those three were added after the 3.40 release; DEGOV1 and ENTSOE_simp were already registered in 3.40. A distribution that does not have them rejects the name with:

STOP CALL FROM tor_TGOV1:
Torque model not found in definition

If you see this, check the banner RAMSES prints at startup. Versions 3.50 and later show a Version: line; if yours does not, upgrade before investigating anything else.

TGOV1D is not a valid data-file name

The TGOV1 model is implemented by a subroutine called tor_TGOV1D, but the name registered for data files is TGOV1 (or tor_TGOV1), without the D. Writing TGOV1D or tor_TGOV1D after TOR produces the same “Torque model not found in definition” error, on every version.

---

DEGOV1 (tor_DEGOV1)

Scientific Description

The DEGOV1 model represents the diesel engine governor as defined in the IEEE Committee Report on governors. It consists of three main stages:

1. Speed governor (electrical control / lead–lag)

The speed error is formed from the measured speed deviation and a reference signal derived from either mechanical power ($P$) or mechanical torque ($T_m$), selected by the switch $SWM$:

$$V_{60} = (1 - SWM) \cdot T_m + SWM \cdot P$$ $$REF = V_{60} \cdot R$$

The governor speed error drives a second-order lead–lag controller (transfer function approximating a two-pole, two-zero system) with time constants $T_1$, $T_2$, $T_3$:

$$G_{gov}(s) \approx \frac{1 + s T_3}{(1 + s T_1)(1 + s T_2)}$$

2. Actuator (fuel injection system)

The governor output passes through a lead–lag block with gain $K$ and time constants $T_4$, $T_6$:

$$G_{act}(s) = K \cdot \frac{1 + s T_4}{1 + s T_6}$$

followed by a first-order lag $T_5$, and an integrator with limits $[T_{MIN},\, T_{MAX}]$.

3. Engine dead time and torque output

The actuator output is subject to engine dead time $T_D$, approximated by a second-order Padé:

$$e^{-sT_D} \approx \frac{1 - 0.5 s T_D + 0.0833 s^2 T_D^2}{1 + 0.5 s T_D + 0.0833 s^2 T_D^2}$$

The final mechanical torque is computed as:

$$T_m = \frac{1}{1 + s T_E} \cdot V_{engine}$$ $$P_m = T_m \cdot \omega$$

The droop characteristic is:

$$\Delta \omega + R \cdot (V_{60} - REF) = 0 \implies \text{error} = \Delta\omega + R \cdot V_{act}$$

Parameters

Parameter	Description
SWM	Input switch: 0 = mechanical torque ($T_m$), 1 = electrical power ($P$)
T1	Governor time constant, lead numerator (s)
T2	Governor time constant, lag denominator (s)
T3	Governor time constant, second-order denominator (s)
K	Actuator gain
T4	Actuator lead time constant (s)
T5	First-order actuator lag (s)
T6	Actuator lag time constant (s)
TMIN	Minimum fuel/torque limit (pu)
TMAX	Maximum fuel/torque limit (pu)
TD	Engine dead time (s)
R	Speed droop (pu/pu)
TE	Engine time constant (s)

Internal parameters: V60 (selected reference input, mechanical torque or electrical power according to SWM) and REF (V60 · R), both set at initialisation

Usage Example

RAMSES Data File

SYNC_MACH g1  g1  1. 1.  0.  0.   600. 570. 6. 0. 2.05
                    XT   0.15  2.2  0.3   0.2   2.   0.4  0.2  0.1  6.0257  0.  7.00  0.05  1.5  0.05
              EXC GENERIC1   3.0618 -0.1  1.  0.  100. -1. -20.0  10.  120. 5.  12.5 0.1  0.  5.
                                1     75.   15.    0.22    0.012     0.22    0.012    -0.1    0.1
              TOR DEGOV1  0      ! SWM: 0 = torque input, 1 = power input
                          0.02   ! T1: governor lead time constant (s)
                          0.02   ! T2: governor lag time constant (s)
                          0.20   ! T3: governor second-order denominator (s)
                          1.0    ! K: actuator gain
                          0.25   ! T4: actuator lead time constant (s)
                          0.009  ! T5: first-order actuator lag (s)
                          0.038  ! T6: actuator lag time constant (s)
                          0.0    ! TMIN: minimum fuel/torque limit (pu)
                          1.05   ! TMAX: maximum fuel/torque limit (pu)
                          0.01   ! TD: engine dead time (s)
                          0.05   ! R: speed droop (pu/pu)
                          0.05 ; ! TE: engine time constant (s)

Notes

• Set SWM = 0 to use mechanical torque as the reference input, SWM = 1 for electrical power.
• TMIN and TMAX are per-unit limits on the integrator output (fuel demand / valve position).
• R is the permanent droop; typical values are 0.04–0.05 pu/pu.
• The Padé approximation of the dead time $T_D$ is a second-order filter.
• Parameters are listed in order: SWM T1 T2 T3 K T4 T5 T6 TMIN TMAX TD R TE.

---

ENTSOE_simp (tor_ENTSOE_simp)

Scientific Description

The ENTSOE_simp model is a simplified ENTSO-E speed governor suitable for primary frequency response studies. It is derived from the ENTSO-E recommendations for equivalent turbine-governor representation.

The governor equation forms a speed error with permanent droop $R$:

$$R \cdot \dot{p}_1 - C + (\omega - 1) = 0, \quad C = T_m \cdot R$$

This error drives a first-order lag (representing the valve or steam chest) with limits $[V_{MIN},\, V_{MAX}]$:

$$\frac{d p_2}{dt} = \frac{1}{T_1}(p_1 - p_2), \quad p_2 \in [V_{MIN},\, V_{MAX}]$$

The turbine mechanical power is modelled by a lead–lag transfer function with time constants $T_2$ (zero) and $T_3$ (pole):

$$P_m(s) = \frac{1 + s T_2}{1 + s T_3} \cdot p_2(s)$$

The final mechanical torque output accounting for shaft speed is:

$$T_m \cdot \omega = P_m$$

Parameters

Parameter	Description
R	Permanent speed droop (pu/pu)
T1	Governor/valve time constant (s)
VMIN	Minimum valve position / lower output limit (pu)
VMAX	Maximum valve position / upper output limit (pu)
T2	Turbine lead time constant, zero (s)
T3	Turbine lag time constant, pole (s)

Internal parameter: C = Tm · R (initialised from the load-flow mechanical torque)

Usage Example

RAMSES Data File

SYNC_MACH g1  g1  1. 1.  0.  0.   400. 360. 6. 0. 2.05
                    XT   0.15  2.2  0.3   0.2   2.   0.4  0.2  0.1  6.0257  0.  7.00  0.05  1.5  0.05
              EXC GENERIC1   3.0618 -0.1  1.  0.  100. -1. -20.0  10.  120. 5.  12.5 0.1  0.  5.
                                1     75.   15.    0.22    0.012     0.22    0.012    -0.1    0.1
              TOR ENTSOE_simp  0.05   ! R: permanent droop (pu/pu)
                               0.50   ! T1: governor/valve time constant (s)
                               0.0    ! VMIN: minimum valve position (pu)
                               1.1    ! VMAX: maximum valve position (pu)
                               0.0    ! T2: turbine lead time constant (s)
                               10.0 ; ! T3: turbine lag time constant (s)

Notes

• Typical primary-frequency response studies use $R = 0.04$–$0.05$.
• Setting $T_2 = 0$ simplifies the turbine to a pure first-order lag $1/(1+sT_3)$.
• This model is commonly used as a simplified equivalent for aggregated generation.
• Parameters are listed in order: R T1 VMIN VMAX T2 T3.

---

GAST (tor_GAST)

Scientific Description

The GAST model represents a gas turbine unit, following the IEEE Committee Report (1973) and the convention common to industry tools. It captures the speed governor, compressor discharge lag, and fuel/combustion dynamics.

Speed governor with droop and load reference:

$$\text{error} = R \cdot (V_{act} - LR) + (\omega - 1) = 0$$

where $LR = T_m$ (load reference, initialised from mechanical torque) and $R$ is the droop.

The speed error drives a value position through a limiter $[V_{MIN},\, V_{MAX}]$ and a first-order lag $T_1$:

$$\frac{d p_2}{dt} = \frac{1}{T_1}(p_1 - p_2)$$

The compressor discharge is modelled by lag $T_2$:

$$\frac{d p_3}{dt} = \frac{1}{T_2}(p_2 - p_3)$$

The mechanical power (including speed-dependent damping $D_{TURB}$) is:

$$P_m = p_3 + D_{TURB} \cdot (\omega - 1)$$

The exhaust temperature is tracked by a lag $T_3$:

$$\frac{d p_4}{dt} = \frac{1}{T_3}(p_3 - p_4)$$

A temperature limit is applied via:

$$p_5 = A_T + K_T \cdot (A_T - p_4)$$

A minimum gate blocks the valve position: $p_1 = \min(p_{gov},\, p_5)$.

The torque-power conversion:

$$T_m \cdot \omega = P_m$$

Parameters

Parameter	Description
R	Permanent speed droop (pu/pu)
T1	Governor/valve time constant (s)
T2	Compressor discharge time constant (s)
T3	Radiation shield / exhaust temperature lag (s)
AT	Ambient temperature load limit (pu)
KT	Temperature control loop gain
VMAX	Maximum valve position (pu)
VMIN	Minimum valve position (pu)
DTURB	Turbine damping factor (pu torque / pu speed)

Internal parameter: LR = Tm (load reference, set at initialisation)

Usage Example

RAMSES Data File

SYNC_MACH g1  g1  1. 1.  0.  0.   400. 360. 6. 0. 2.05
                    XT   0.15  2.2  0.3   0.2   2.   0.4  0.2  0.1  6.0257  0.  7.00  0.05  1.5  0.05
              EXC GENERIC1   3.0618 -0.1  1.  0.  100. -1. -20.0  10.  120. 5.  12.5 0.1  0.  5.
                                1     75.   15.    0.22    0.012     0.22    0.012    -0.1    0.1
              TOR GAST  0.05   ! R: permanent droop (pu/pu)
                        0.40   ! T1: governor/valve time constant (s)
                        0.10   ! T2: compressor discharge time constant (s)
                        3.00   ! T3: exhaust temperature lag (s)
                        1.00   ! AT: ambient temperature load limit (pu)
                        2.50   ! KT: temperature control loop gain
                        1.05   ! VMAX: maximum valve position (pu)
                        0.0    ! VMIN: minimum valve position (pu)
                        0.0  ; ! DTURB: turbine damping factor

Notes

• Based on the IEEE Committee Report on “Dynamic Models for Steam and Hydro Turbines in Power System Studies” (1973), later adapted for gas turbines.
• AT and KT define the exhaust-temperature protection characteristic.
• DTURB = 0 disables speed-dependent damping.
• Parameters are listed in order: R T1 T2 T3 AT KT VMAX VMIN DTURB.

---

TGOV1 (tor_TGOV1D)

Scientific Description

The TGOV1 model represents a simple steam turbine governor, based on the IEEE TGOV1 structure with an added damping term. It is one of the most widely used simple governor models in power-system stability studies.

Speed governor with permanent droop:

The speed error (with droop $R$) drives a first-order lag $T_1$ with output limits $[V_{MIN},\, V_{MAX}]$:

$$R \cdot p_1 - C + (\omega - 1) = 0, \quad C = T_m \cdot R$$ $$\frac{d p_2}{dt} = \frac{1}{T_1}(p_1 - p_2), \quad p_2 \in [V_{MIN},\, V_{MAX}]$$

Turbine with reheater and damping:

The valve position passes through a lead–lag block representing the steam chest and reheater:

$$P_m(s) = \frac{1 + s T_2}{1 + s T_3} \cdot p_2(s)$$

The total mechanical power includes a speed-dependent damping term $D_t$:

$$P_m = p_{turbine} + D_t \cdot (\omega - 1)$$

Hence the mechanical torque:

$$T_m = \frac{P_m}{\omega}$$

Parameters

Parameter	Description
R	Permanent speed droop (pu/pu)
T1	Steam chest / valve actuator time constant (s)
VMAX	Maximum valve position (pu)
VMIN	Minimum valve position (pu)
T2	Lead time constant, reheater zero (s)
T3	Lag time constant, reheater pole (s)
Dt	Turbine damping coefficient (pu torque / pu speed deviation)

Internal parameter: C = Tm · R (initialised from load-flow mechanical torque)

Usage Example

RAMSES Data File

SYNC_MACH g1  g1  1. 1.  0.  0.   400. 360. 6. 0. 2.05
                    XT   0.15  2.2  0.3   0.2   2.   0.4  0.2  0.1  6.0257  0.  7.00  0.05  1.5  0.05
              EXC GENERIC1   3.0618 -0.1  1.  0.  100. -1. -20.0  10.  120. 5.  12.5 0.1  0.  5.
                                1     75.   15.    0.22    0.012     0.22    0.012    -0.1    0.1
              TOR TGOV1  0.05   ! R: permanent droop (pu/pu)
                          0.50   ! T1: steam chest/valve actuator time constant (s)
                          1.05   ! VMAX: maximum valve position (pu)
                          0.0    ! VMIN: minimum valve position (pu)
                          2.10   ! T2: lead time constant, reheater zero (s)
                          7.00   ! T3: lag time constant, reheater pole (s)
                          0.0  ; ! Dt: turbine damping coefficient

Notes

• This is essentially the IEEE TGOV1 model with an additional damping term $D_t$.
• Setting $T_2 = 0$ gives a pure first-order turbine $1/(1+sT_3)$.
• $D_t > 0$ adds a stabilising speed-dependent power correction (useful for islanded operation).
• Parameters are listed in order: R T1 VMAX VMIN T2 T3 Dt.

---

HYGOV (tor_hygov)

Scientific Description

The HYGOV model represents a hydraulic turbine and governor following a simplified penstock/water-column formulation, consistent with the IEEE representation for hydro governors (IEEE Std 1110).

Governor with droop and PI controller:

The speed error (with permanent droop $R$ and transient droop $r$) enters a lag $T_f$ to produce the error signal $e$:

$$\text{input} = 1 - \omega - R \cdot (c - P_0)$$ $$\frac{d e}{dt} = \frac{1}{T_f}\left(\text{input} - e\right)$$

The rate of change of gate demand is computed via the transient droop:

$$\dot{x}_2 = \frac{e}{r \cdot T_r}$$

This is rate-limited to $[-V_{ELM},\, +V_{ELM}]$, then integrated with gate limits $[G_{min},\, G_{max}]$:

$$\frac{d x_4}{dt} = x_3, \quad x_4 \in [G_{min},\, G_{max}]$$

The PI controller output (desired gate) is:

$$x_5 = x_4 + \frac{e}{r}, \quad c = \text{clip}(x_5,\, G_{min},\, G_{max})$$

The actual gate position follows through the servo:

$$\frac{d g}{dt} = \frac{1}{T_g}(c - g)$$

Penstock / water column:

The head deviation $dH$ is determined by the non-linear water flow equation and water-starting time $T_W$:

$$1 - \left(\frac{Q}{g}\right)^2 = dH$$ $$T_W \cdot \frac{dQ}{dt} = dH$$

Turbine mechanical torque:

$$T_m \cdot \omega = A_t \cdot (1 - dH)(Q - Q_{nl}) - D_{turb} \cdot (1 - \omega) \cdot g$$ $$P_m = T_m \cdot \omega$$

Parameters

Parameter	Description
R	Permanent droop (pu/pu)
r	Transient droop (pu/pu)
Tr	Transient droop reset time (s)
Tf	Filter time constant for speed error (s)
Tg	Gate servo time constant (s)
VELM	Gate velocity limit (pu/s)
Gmax	Maximum gate opening (pu)
Gmin	Minimum gate opening (pu)
Tw	Water starting time (s)
At	Turbine gain (pu power / pu flow)
Dturb	Turbine damping factor
Qnl	No-load water flow (pu)

Internal parameter: Po = (P / At) + Qnl (initial gate setpoint from load-flow)

Usage Example

RAMSES Data File

SYNC_MACH g1  g1  1. 1.  0.  0.   800. 760. 3. 0. 0.95
                    XT   0.15  1.1  0.25  0.2  0.7  *  0.2  0.1  6.0257  0.  5.00  0.05  *  0.1
              EXC GENERIC1   1.8991 -0.1  0.  1.  100. -1. -11  10.  70.  10.  20. 0.1  0.  4.
                                1     75.   15.    0.2    0.01     0.2    0.01    -0.1    0.1
              TOR HYGOV  0.05   ! R: permanent droop (pu/pu)
                         0.30   ! r: transient droop (pu/pu)
                         5.00   ! Tr: transient droop reset time (s)
                         0.05   ! Tf: filter time constant for speed error (s)
                         0.20   ! Tg: gate servo time constant (s)
                         0.20   ! VELM: gate velocity limit (pu/s)
                         1.00   ! Gmax: maximum gate opening (pu)
                         0.0    ! Gmin: minimum gate opening (pu)
                         1.50   ! Tw: water starting time (s)
                         1.10   ! At: turbine gain (pu power / pu flow)
                         0.50   ! Dturb: turbine damping factor
                         0.05 ; ! Qnl: no-load water flow (pu)

Notes

• Tw (water starting time) is the dominant parameter controlling frequency response; typical values are 0.5–2 s.
• r > R is required for stable regulation; set $r \approx 2$–5 $\times R$.
• Tr is the reset time for transient droop; values of 5–30 s are typical.
• Non-linear head-flow equation makes this model suitable for large transients.
• Parameters are listed in order: R r Tr Tf Tg VELM Gmax Gmin Tw At Dturb Qnl.