1.2. Dynamic data

Dynamic data define the models used to simulate the time-domain response of power system components. They are loaded into RAMSES via pyramses.cfg.addData().

1.2.1. Data file format

RAMSES data files are text-based. Records are terminated with a semicolon (;). Comments begin with ! (retained in output) or # (discarded). Fields are free-format: 30, 30., and 3E01 are equivalent. Character fields are case-sensitive; use quotes for names containing spaces or slashes. Records can span multiple lines.

1.2.2. Models included in the current version

Category	Models
Injectors	load, PQ, restld, indmach1, indmach2, IBG, WT3WithChanges, WT4WithChanges, BESSWithChanges, vfd_load, svc_hq_generic1, theveq
Exciters	ST1A, ST1A_lim, ST1A_PSS2B, ST1A_PSS3B, ST1A_PSS4B, ST1A_IEEEST, ST1A_OELHQ, ST1A_PSS2B_OELHQ, ST1A_PSS3B_OELHQ, ST1A_PSS4B_OELHQ, ST1A_PSS2B_MAXEX2, ST1A_PSS4B_MAXEX2, ST1A_IEEEST_MAXEX2, ST2A, AC1A, AC1A_RETRO, AC1A_RETRO_PSS4B, AC1A_OELHQ, AC1A_MAXEX2, AC4A, AC8B, AC8B_PSS3B_lim, DC3A, IEEET5, EXPIC1, EXPIC1_PSS2B, EXPIC1_PSS2B_MAXEX2, EXHQSC, EXHQSC_MAXEX2, EXHQSC_PSS4B, EXHQSC_PSS4B_OELHQ, EXHQSC_PSS4B_MAXEX2, ENTSOE_simp, GENERIC3, GENERIC4, generic1, generic2, hq_generic1, kundur, 1storder, constant
Speed governors	DEGOV1, hydro_generic1, thermal_generic1, HQRVC, HQRVM, HQRVN, HQRVW, ENTSOE_simp, ENTSOE_simp_consensus, ENTSOE_simp_consensus_mod, hq_generic, hq_generic1, 1storder, constant
Two-ports	HQSVC, HVDC_LCC, HVDC_VSC, HVDC_VSC_SC, DC_BHPM, DC_CHAAUT, CHENIER, CSVGN5, DCL_WCL, vsc_hq
Discrete controllers	ltc, ltc2, ltcinv, oltc2, uvls, uvprot, pst, rt, mais, HQmais, FRT, sim_minmaxvolt, sim_minmaxspeed, voltage_variability

1.2.3. Synchronous generator

The synchronous machine model used in RAMSES is a standard 6th-order (or reduced) flux-linkage model. It is declared implicitly through the SYNC_MACH record and must have an associated exciter (EXC) and torque controller (TOR).

SYNC_MACH name bus SNOM FP FQ P Q H D Ra Xd Xdp Xdpp Td0p Td0pp Xq Xqp Xqpp Tq0p Tq0pp Xl ;

Declares a synchronous machine and connects it to a bus.

Parameters

• name (str) – (max 8 characters) name of the machine

• bus (str) – (max 8 characters) connection bus

• SNOM (float) – nominal apparent power, in MVA

• FP (float) – fraction of active power (0–1), used for initialisation

• FQ (float) – fraction of reactive power (0–1), used for initialisation

• P (float) – scheduled active power, in MW (used when FP = 0)

• Q (float) – scheduled reactive power, in Mvar (used when FQ = 0)

• H (float) – inertia constant, in seconds

• D (float) – damping coefficient, in pu

• Ra (float) – armature resistance, in pu

• Xd (float) – d-axis synchronous reactance, in pu

• Xdp (float) – d-axis transient reactance, in pu

• Xdpp (float) – d-axis subtransient reactance, in pu

• Td0p (float) – d-axis open-circuit transient time constant, in seconds

• Td0pp (float) – d-axis open-circuit subtransient time constant, in seconds

• Xq (float) – q-axis synchronous reactance, in pu

• Xqp (float) – q-axis transient reactance, in pu

• Xqpp (float) – q-axis subtransient reactance, in pu

• Tq0p (float) – q-axis open-circuit transient time constant, in seconds

• Tq0pp (float) – q-axis open-circuit subtransient time constant, in seconds

• Xl (float) – leakage reactance, in pu

See the synchronous machine model reference for equations and parameter definitions.

1.2.4. Excitation system (EXC)

Exciters are attached to synchronous machines and control the field voltage. They are declared as follows:

EXC MODEL_NAME MACHINE_NAME DATA1 DATA2 ... ;

where MODEL_NAME is one of the supported exciter models (e.g., ST1A, AC1A, DC3A), and MACHINE_NAME is the name of the associated synchronous machine.

1.2.5. Speed governor / torque controller (TOR)

Governors are attached to synchronous machines and control mechanical torque:

TOR MODEL_NAME MACHINE_NAME DATA1 DATA2 ... ;

1.2.6. Injectors (INJEC)

Injectors are single-bus dynamic components representing loads, renewable energy sources, BESS, and other shunt-connected devices:

INJEC MODEL_NAME INJ_NAME BUS FP FQ P Q DATA1 DATA2 ... ;

param str MODEL_NAME

injector model type (e.g., IBG, WT3WithChanges, load, PQ)

param str INJ_NAME

name of the injector (max 20 characters)

param str BUS

connection bus

param float FP

fraction of total active power at bus (0–1). If non-zero, P is inferred from bus power.

param float FQ

fraction of total reactive power at bus (0–1). If non-zero, Q is inferred from bus power.

param float P

active power injection, in MW (used when FP = 0)

param float Q

reactive power injection, in Mvar (used when FQ = 0)

param …

model-specific data parameters

Special injector types:

• theveq — Thévenin equivalent (infinite bus). Forces synchronous reference frame.

• load — Voltage-dependent load model.

• PQ — Constant P and Q load.

• IBG — Inverter-based generator (grid-following).

• WT3WithChanges / WT4WithChanges — Type 3 and Type 4 wind turbines.

• BESSWithChanges — Battery energy storage system.

1.2.7. Two-port models (TWOP)

Two-port models connect two buses and represent HVDC links, SVCs, and other series-connected devices:

TWOP MODEL_NAME TWOP_NAME BUS1 BUS2 IND FP1 FQ1 P1 Q1 FP2 FQ2 P2 Q2 DATA1 DATA2 ... ;

param str MODEL_NAME

two-port model type (e.g., HVDC_VSC, HVDC_LCC, HQSVC)

param str TWOP_NAME

name of the element (max 20 characters)

param str BUS1

first terminal bus

param str BUS2

second terminal bus

param int IND

indicator for power initialisation (0 = use FP/FQ, 1 = use P/Q directly)

param float FP1, FQ1

fraction of active/reactive power at bus 1

param float P1, Q1

active/reactive power injection at bus 1, in MW/Mvar

param float FP2, FQ2

fraction of active/reactive power at bus 2

param float P2, Q2

active/reactive power injection at bus 2, in MW/Mvar

param …

model-specific data parameters

1.2.8. Discrete controllers (DCTL)

Discrete controllers implement switching logic and automata-based control actions. They can control network devices, change parameters, or implement protection schemes:

DCTL MODEL_NAME DCTL_NAME BUS DATA1 DATA2 ... ;

Common discrete controller models:

Model	Description
ltc	Load tap-changer controller. Adjusts transformer ratio to regulate voltage.
ltc2	Load tap-changer with dead-band and discrete steps.
ltcinv	Inverse LTC (raises voltage when below setpoint).
oltc2	On-load tap changer with discrete step logic.
uvls	Under-voltage load shedding scheme.
uvprot	Under-voltage protection relay.
pst	Phase-shifting transformer controller.
rt	Ratio transformer (manual ratio control).
mais	Multi-area interaction signal controller.
FRT	Fault-ride-through logic for renewable generators.
sim_minmaxvolt	Simulation stopping criterion: minimum/maximum voltage.
sim_minmaxspeed	Simulation stopping criterion: minimum/maximum machine speed.
voltage_variability	Monitors voltage variability and can trigger events.

1.2.9. Constant-impedance loads

Loads modelled as constant impedance (converted at initialisation from the power-flow solution):

IMPLOAD bus ;

Loads on buses with name prefix M_ are automatically treated as constant-impedance loads.