Compensation and Measurement

Two injector models that are neither loads nor generators: a static var compensator and a phasor measurement unit.

The INJEC record these models are entered with, and the rules on model names, are on the Injector Models page.

SVC_GENERIC1 (inj_svc_generic1): Generic Static Var Compensator

The data-file model name is SVC_GENERIC1. It takes no prefix.

Description

A dynamic SVC injecting a purely reactive current at its bus. A PI voltage regulator with droop drives a susceptance $B_{svc}$ between Bmin and Bmax, and two lead-lag stabiliser channels can add a supplementary signal to the voltage reference. This is the dynamic counterpart of the static SVC record used by the power flow: the static record fixes the operating point, this model governs how the device behaves during the simulation.

The voltage reference is initialised from the power flow solution, so that the model starts in equilibrium:

$V_{ref} = V_0 + B_p \cdot B_{svc,0}$

where $B_p$ is the droop and $B_{svc,0}$ the initial susceptance implied by the reactive current at the bus.

Parameters

The record carries 17 data parameters, in order:

#	Name	Description
1	G1	Gain of the first stabiliser channel
2	T1	Time constant of the first stabiliser channel (s)
3	a	Lead-lag coefficient of the first channel
4	K1	Output gain of the first channel
5	L1	Output limit of the first channel (pu)
6	G2	Gain of the second stabiliser channel
7	T2	Time constant of the second stabiliser channel (s)
8	b	Lead-lag coefficient of the second channel
9	K2	Output gain of the second channel
10	L2	Output limit of the second channel (pu)
11	Ltot	Limit on the summed stabiliser output (pu)
12	Kp	Proportional gain of the voltage regulator
13	Ki	Integral gain of the voltage regulator
14	Bp	Droop, in pu on the SVC base
15	Bmax	Maximum susceptance (Mvar at 1 pu voltage)
16	Bmin	Minimum susceptance (Mvar at 1 pu voltage)
17	Bnom	Susceptance base used for the per-unit conversion (Mvar)

One additional parameter is computed at initialisation:

#	Name	Description
18	Vref	Voltage reference, set from the power flow solution

Observables

Q, dvpss, Bsvc, Vref, Vb

---

PMU (inj_PMU): Phasor Measurement Unit

The data-file model name is PMU (or inj_PMU).

Description

A measurement-only injector: it injects zero current at its bus and exists purely to expose bus quantities as observables. It reports a filtered local frequency estimate computed the same way as the f_inj block, together with the bus voltage magnitude and angle and the speed and angle of the moving DQ reference frame. Attach one to any bus whose frequency you want to record without perturbing the solution.

The frequency estimate is a first-order filter on the bus voltage phasor. The measurement time constant is clamped to a floor of 0.05 s, so values below that have no effect.

Parameters

#	Name	Description	Unit
1	Tf	Frequency measurement time constant, recommended 0.05 to 0.10; values below 0.05 are clamped	s

Three additional parameters are set at initialisation: wnom (nominal angular frequency), vm0 and va0 (the initial bus voltage magnitude and angle).

Observables

Name	Description	Unit
f	Estimated bus frequency	pu of $f_{nom}$
vm	Bus voltage magnitude	pu
va	Bus voltage phase angle in the moving DQ frame, wrapping at $\pm\pi$	rad
thref	Accumulated angle of the DQ reference frame with respect to the nominally rotating frame, zero at $t = 0$	rad
dwref	Speed deviation of the DQ reference frame from nominal	rad/s

Caution

dwref and thref are only meaningful under $OMEGA_REF COI. With $OMEGA_REF SYN the reference frame rotates at nominal speed by construction, so both stay at zero.

Usage Example

Show the data record

INJEC  PMU  PMU_1041  1041
      # FP FQ P Q: share of the power-flow injection (FP, FQ) or initial power (P in MW, Q in Mvar)
      0.  0.  0.  0.
      # Tf: Frequency measurement time constant, recommended 0.05 to 0.10; values below 0.05 are clamped (s)
      0.05
;

All four participation and power fields are zero: the model neither consumes nor produces power.