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.

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  ... ;

tor_DEGOV1

Scientific Description

The tor_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)

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)

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.

tor_ENTSOE_simp

Scientific Description

The tor_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
Notes

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)

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.

tor_GAST

Scientific Description

The tor_GAST model represents a gas turbine unit, following the IEEE Committee Report (1973) and the NEPLAN/PowerWorld convention. 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
Notes

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

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.

tor_TGOV1D

Scientific Description

The tor_TGOV1D 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
Notes

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 TGOV1D  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

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.

tor_hygov

Scientific Description

The tor_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
Notes

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)

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.