WECC Wind and Storage

The three models on this page are assembled from WECC generic blocks: WT3 and WT4 from the second-generation renewable energy system blocks, and BESS from REPC_A, REEC_C and REGC_A. WECC Model Status comes first because it applies to both wind turbine models: it lists the blocks RAMSES implements, their approval status and the newer blocks it does not implement.

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

WECC Model Status

WT3 and WT4 are assembled from the WECC second-generation generic renewable energy system (RES) blocks. Their specification dates from January 2014 [1, 2, 3], and WECC approved the blocks on 19 March 2014 [4]. They are not the first-generation WECC wind models (wt3g, wt3e, wt3t, wt3p, wt4g, wt4e, wt4t), which WECC retired on 22 April 2020 [4]; the EPRI user guide [8] explains how to convert data written for those.

Every block that RAMSES implements is still on the WECC approved model list (version September 2026, effective 18 September 2026) [4]. WECC has specified and approved newer blocks since, and RAMSES implements none of them. Statuses and dates below are those of the approved list [4].

Implemented in RAMSES

WECC block	Role	WECC status	WT3	WT4
REGC_A	Generator/converter interface, current source	Approved 19 March 2014	Yes	Yes
REEC_A	Electrical control	Approved 19 March 2014	Yes	Yes
REPC_A	Plant control	Approved 19 March 2014	Yes	Yes
WTGT_A	Two-mass drivetrain	Approved 19 March 2014	Yes	Yes
WTGA_A (WTGAR_A here)	Aerodynamics	Approved 19 March 2014	Yes	No
WTGP_A (WTGPT_A here)	Pitch control	Approved 19 March 2014	Yes	No
WTGQ_A (WTGTRQ_A here)	Torque control	Approved 19 March 2014	Yes	No

The PLL of both models (parameters vPLL to wrefPLL) is not one of the WECC blocks. RAMSES uses the block names of the 2014 reports, which are also those of PowerWorld; WECC’s own names are in the first column.

Not implemented in RAMSES

WECC block	Role	WECC status	Specification
REGC_B	Generator/converter interface, voltage source, for weak grids	Approved 25 August 2020	[5]
REGC_C	Voltage source with a PLL and inner current loops	Not on the approved list	[5]
REEC_D	Electrical control with extended voltage-dependent current limits	Approved 25 August 2020	[5]
REEC_E	REEC_D with local PI control of Q, power factor and P	Approved 11 September 2025	[6]
REPC_C	Plant control with power factor control and switched shunts	Approved 1 December 2021	[5]
REPC_D	REPC_C controlling several aggregated units	Approved 24 January 2024	[6]
REPC_E	Plant control built on REPC_D	Approved 17 September 2026	[4]
WTGT_B	Drivetrain for Type 4 turbines	Approved 1 December 2021	[5]
WTGP_B	Pitch control with more flexible limits	Approved 1 December 2021	[5]
WTGWGO_A	Weak-grid option, auxiliary control for Type 4	Approved 1 December 2021	[5]
WTGIBFFR_A	Inertia-based fast frequency response, auxiliary control	Approved 26 January 2022	[5]

REPC_B, the earlier hybrid-plant controller, was withdrawn from the approved list on 29 January 2026 and retired on 23 August 2026 [4]; RAMSES never implemented it. The storage and grid-forming blocks on the same list (REEC_C, REGFM_A1, REGFM_B1, REGFM_C1, REPCGFM_C1) are outside the scope of these two models.

Type 4 drivetrain. WECC states that a Type 4 turbine needs none of the mechanical blocks for stability studies, and recommends WTGT_B over WTGT_A when the torsional ripple in the electrical power is to be emulated, because of a problem seen with WTGT_A on Type 4 units [7]. RAMSES WT4 has WTGT_A only. Set PFlag = 0 to take the drivetrain out of the output entirely.

References

1. WECC, WECC Second Generation Wind Turbine Models, 23 January 2014. PDF (BPA mirror)
2. P. Pourbeik (EPRI), WECC Type 3 Wind Turbine Generator Model, Phase II, 23 January 2014. PDF
3. P. Pourbeik (EPRI), WECC Type 4 Wind Turbine Generator Model, Phase II, 23 January 2013. PDF
4. WECC, Approved Dynamic Models, version September 2026, effective 18 September 2026. PDF
5. P. Pourbeik, Proposal for New Features for the Renewable Energy System Generic Models, memo to WECC REMWG, revision 27, 16 February 2023. PDF
6. P. Pourbeik, Proposal for New Plant Controller and Electrical Controller, memo to WECC REMWG, 15 January 2024. PDF
7. WECC REMWG, Brief Summary of all 2nd Generation Generic Renewable Energy System Dynamic Models, February 2021. PDF
8. EPRI, Model User Guide for Generic Renewable Energy System Models, product 3002014083, 2018. PDF (BPA mirror)

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WT3 (inj_WT3): Type 3 Wind Turbine (DFIG)

The data-file model name is WT3 (or inj_WT3).

Note

Available from RAMSES 3.50. The parameter list below has not changed since that release.

Description

A generic Type 3 (doubly-fed induction generator) wind turbine built from the WECC second-generation renewable blocks. As in the WECC model, the machine and its rotor-side converter are not represented electrically: the generator/converter block injects a controlled current into the network, and the mechanical side only shapes the active power order. The model has six WECC blocks and a PLL, laid out in the data record in this order:

Block	Role	WT3 #
SNOM	Rating, the per-unit base of the model	1
REPC_A	Plant controller: voltage or reactive power regulation, frequency droop	2–32
WTGTRQ_A	Torque controller: speed reference from a power-speed table, PI on speed or power error	33–46
WTGPT_A	Pitch controller: limits rotor over-speed and power	47–56
WTGAR_A	Aerodynamics: mechanical power as a function of pitch angle	57–58
WTGT_A	Two-mass drivetrain	59–62
REEC_A	Electrical controller: Q/V loops, voltage-dip logic, current limits, power order	63–111
REGC_A	Generator/converter interface: current lags, high- and low-voltage current management	112–124
PLL	Angle of the injected current	125–128

Per-unit base. Every power, current and torque inside the model is in per unit on SNOM (MVA), not on the system base. Only the injected currents $i_x$, $i_y$ seen by the network are converted to the system base.

Wind speed is not an input. The aerodynamic block takes its available power $P_{mo}$ from the initial electrical power of the power flow, so the model represents a turbine running at constant wind.

Scientific Description

The equations below are those coded in RAMSES. A flag ”= 1” is tested in the dynamics as flag $\geq 0.5$, but initialization tests for exactly 1, so give every flag as exactly 0 or 1.

Measurements. With $v_t = |\bar V|$ the terminal voltage:

$P_e = (v_x i_x + v_y i_y)\frac{S_{\mathrm{base}}}{S_{\mathrm{nom}}}, \qquad Q_{\mathrm{gen}} = (v_y i_x - v_x i_y)\frac{S_{\mathrm{base}}}{S_{\mathrm{nom}}}$

REPC_A, plant controller: voltage or reactive power. The regulated point is the terminal, shifted by a compensation impedance: $\bar v_{\mathrm{con}} = \bar V - (R_c + jX_c)\bar I$, and $P_{\mathrm{branch}}$, $Q_{\mathrm{branch}}$ are the powers through that point. The measured quantity is

$Y_1 = \begin{cases} |\bar v_{\mathrm{con}}| & \text{vcompFlag} = 1 \\ v_t + K_c\,Q_{\mathrm{branch}} & \text{vcompFlag} = 0 \end{cases}$

filtered by $1/(1+sT_{\mathrm{fltr}})$. The error is $v_{\mathrm{ref}} - Y_2$ when RefFlag = 1 and $Q_{\mathrm{ref}} - Q_{\mathrm{branch}}/(1+sT_{\mathrm{fltr}})$ when RefFlag = 0. It passes a symmetric deadband $\pm$dbd, the limits [emin, emax], and a PI controller (Kp, Ki) whose integrator and output are both limited to [Qmin, Qmax]. The integrator is frozen while $v_t <$ vfrz. A lead-lag $(1+sT_{ft})/(1+sT_{fv})$ follows; with $T_{fv} < 0.005$ s it is bypassed. Its output becomes the reactive power reference $Q_{\mathrm{ext}}$ of REEC_A only when QextFlag = 1; with QextFlag = 0, $Q_{\mathrm{ext}}$ stays at its initial value.

REPC_A, plant controller: frequency. The bus frequency is estimated from the rotation of the voltage phasor filtered with $T_m = \max(0.05, T_{\mathrm{mesf}})$:

$f = \frac{(v_y - v_{yf})\,v_{xf} - (v_x - v_{xf})\,v_{yf}}{2\pi f_{\mathrm{nom}}\, T_m\,(v_{xf}^2 + v_{yf}^2)} + \omega_{\mathrm{ref}}$

where $\omega_{\mathrm{ref}}$ is 1 or the centre-of-inertia speed, following $OMEGA_REF. The frequency error $\Delta f = 1 - f$ passes the deadband [fdbd1, fdbd2] and the droops:

$e_P = P_{\mathrm{plantref}} - \frac{P_{\mathrm{branch}}}{1+sT_p} + \min(D_{dn}\Delta f, 0) + \max(D_{up}\Delta f, 0)$

so Ddn acts on over-frequency and Dup on under-frequency. $e_P$ is limited to [femin, femax] and fed to a PI (kpg, kig) limited to [Pmin, Pmax], then a lag $1/(1+sT_{\mathrm{lag}})$. The result replaces the active power reference $P_{\mathrm{refo}}$ only when FreqFlag = 1.

WTGTRQ_A, torque controller. The electrical power is filtered, $x_{27} = P_e/(1+sT_p)$, and a piecewise-linear table through (p1, spd1) … (p4, spd4), flat outside its end points, gives the speed reference:

$\omega_{\mathrm{ref}} = \frac{f_{\mathrm{spd}}(x_{27})}{1 + sT_{\mathrm{wref}}}$

The error is $(P_{\mathrm{refo}} - x_{27})/\omega_g$ when Tflag = 1 (power error) and $\omega_g - \omega_{\mathrm{ref}}$ when Tflag = 0 (speed error). A PI (Kpp, Kip), integrator and output limited to [Temin, Temax], gives the torque order $P_{\mathrm{ref}}$. The integrator is frozen during a voltage dip.

WTGPT_A, pitch controller. Two PI controllers, each limited to [ThetaMin, ThetaMax], act on the speed error and on the power error:

$e_\omega = \omega_t - \omega_{\mathrm{ref}} + K_{cc}(P_{\mathrm{ord}} - P_{\mathrm{refo}}), \qquad e_P = P_{\mathrm{ord}} - P_{\mathrm{refo}}$

(Kpw, Kiw) on $e_\omega$ and (Kpc, Kic) on $e_P$. Their sum drives the actuator lag $1/(1+sT_\theta)$, with the rate limited to [dThetaMin, dThetaMax] and the angle to [ThetaMin, ThetaMax].

WTGAR_A, aerodynamics.

$P_m = P_{mo} - K_a\,\theta\,(\theta - \theta_0), \qquad P_{mo} = P_{e0}$

The pitch angle unit is whatever the data uses, conventionally degrees; Ka must be given per that unit squared.

WTGT_A, two-mass drivetrain. With $T_m = P_m/\omega_t$ and $T_e = P_e/\omega_g$:

$2H_t\frac{d\Delta\omega_t}{dt} = T_m - K_{\mathrm{shaft}}\Delta\theta - D_{\mathrm{shaft}}(\Delta\omega_t - \Delta\omega_g)$

$2H_g\frac{d\Delta\omega_g}{dt} = K_{\mathrm{shaft}}\Delta\theta + D_{\mathrm{shaft}}(\Delta\omega_t - \Delta\omega_g) - T_e$

$\frac{d\Delta\theta}{dt} = \Delta\omega_t - \Delta\omega_g, \qquad \omega_t = \omega_o + \Delta\omega_t, \quad \omega_g = \omega_o + \Delta\omega_g$

The twist equation carries no base angular frequency, so $\Delta\theta$ is in pu·s and Kshaft in pu torque per pu·s. A stiffness quoted per electrical radian must be multiplied by $2\pi f_{\mathrm{nom}}$. The initial speed $\omega_o$ is read off the power-speed table at $P_{e0}$, so it is generally not 1.

REEC_A, electrical controller: voltage dip. A dip is declared when the unfiltered $v_t <$ vdip or $v_t >$ vup. During a dip the integrators of the Q, V and torque PIs, the Tiq lag and the power order lag are frozen, and the reactive current injection

$I_{q,\mathrm{inj}} = \mathrm{lim}_{[I_{ql1},\, I_{qh1}]}\Big(k_{qv}\,\mathrm{db}_{[dbd1,\, dbd2]}\big(v_{\mathrm{ref0}} - v_{t,\mathrm{filt}}\big)\Big)$

is added to the reactive current command, with $v_{t,\mathrm{filt}} = v_t/(1+sT_{rv})$. After the dip ends, Thld selects what happens for $|$Thld$|$ seconds: with Thld $> 0$, $I_{q,\mathrm{inj}}$ is held at Iqfrz; with Thld $< 0$, the injection law above stays active; with Thld $= 0$, $I_{q,\mathrm{inj}}$ returns to zero at once. The active current limit $I_{p\max}$ is frozen during the dip and for Thld2 seconds after it.

REEC_A, reactive power chain. The reactive power reference is

$Q_r = \mathrm{lim}_{[q_{\min},\, q_{\max}]}\begin{cases} x_{27}\tan(\mathrm{pfaref}) & \text{PFFlag} = 1 \text{ (constant power factor)} \\ Q_{\mathrm{ext}} & \text{PFFlag} = 0 \end{cases}$

With QFlag = 0 the reactive current command is $\big(Q_r/v_{t,\mathrm{filt}}\big)/(1+sT_{iq})$. With QFlag = 1 it is the output of a voltage PI (kvp, kvi) on $V_{\mathrm{ref}} - v_{t,\mathrm{filt}}$, limited to [$I_{q\min}$, $I_{q\max}$], where

$V_{\mathrm{ref}} = \mathrm{lim}_{[v_{\min},\, v_{\max}]}\begin{cases} \text{Q PI } (k_{qp}, k_{qi}) \text{ on } Q_r - Q_{\mathrm{gen}} & \text{vFlag} = 1 \\ Q_r + v_{\mathrm{ref1}} & \text{vFlag} = 0 \end{cases}$

In both cases $I_{q\mathrm{cmd}} = \mathrm{lim}_{[I_{q\min},\, I_{q\max}]}(I_{q,\mathrm{inj}} + \cdots)$.

REEC_A, active power chain. $P_{\mathrm{ref}}$ is rate-limited to [dPmin, dPmax] (per second). With PFlag = 1 it is multiplied by $\omega_g$, which makes $P_{\mathrm{ref}}$ a torque and lets drivetrain oscillations reach the output. Then

$T_{\mathrm{pord}}\frac{dP_{\mathrm{ord}}}{dt} = P_{\mathrm{ref}}\,\omega_g^{\,\mathrm{PFlag}} - P_{\mathrm{ord}}, \quad P_{\mathrm{ord}} \in [p_{\min}, p_{\max}], \qquad I_{p\mathrm{cmd}} = \mathrm{lim}_{[0,\, I_{p\max}]}\frac{P_{\mathrm{ord}}}{\max(v_{t,\mathrm{filt}}, 0.01)}$

REEC_A, current limits. VDL1 (vq1…Iq4) and VDL2 (vp1…Ip4) are piecewise-linear functions of $v_{t,\mathrm{filt}}$, flat beyond their end points. With $I_{q\min} = -I_{q\max}$:

PQFlag	$I_{q\max}$	$I_{p\max}$
0 (Q priority)	$\min(\mathrm{VDL1}, I_{\max})$	$\min\big(\mathrm{VDL2}, \sqrt{I_{\max}^2 - I_{q\mathrm{cmd}}^2}\big)$
1 (P priority)	$\min\big(\mathrm{VDL1}, \sqrt{I_{\max}^2 - I_{p\mathrm{cmd}}^2}\big)$	$\min(\mathrm{VDL2}, I_{\max})$

REGC_A, generator/converter. Both current commands pass a lag of time constant Tg. The rate of the reactive current is limited in one direction only, chosen from the sign of the initial reactive power: by Iqrmax if $Q_0 > 0$, by Iqrmin if $Q_0 < 0$, not at all if $Q_0 = 0$. The rise of the active current is limited to rrpwr per second at all times. High-voltage reactive current management and low-voltage active current management then give the injected currents:

$I_{qf} = \frac{\max\big(I_q v_t - \max(0,\, K_{hv}(v_t - V_{olim})),\ \text{QMIN}\big)}{v_t/(1+sT_{\mathrm{fltr}})}, \qquad I_{pf} = m(v_t)\, I_p$

where $K_{hv}$ is accel, $V_{olim}$ is vtmax, and $m$ rises linearly from 0 at lvpnt0 to 1 at lvpnt1. When Lvplsw = 1, $I_p$ is also capped by the low-voltage power logic: zero below zerox, rising linearly to Lvpl1 at Brkpt, no cap above Brkpt. The voltage it uses is $v_t/(1+sT_{\mathrm{fltr}})$.

PLL. The voltage components are filtered with $T_{\mathrm{fltr}}$ and

$v_q = -v_{xf}\sin\theta_{\mathrm{pll}} + v_{yf}\cos\theta_{\mathrm{pll}}, \qquad \omega_{\mathrm{pll}} = k_{p,\mathrm{PLL}}\,v_q + k_{i,\mathrm{PLL}}\!\int v_q\,dt, \qquad \frac{d\theta_{\mathrm{pll}}}{dt} = \omega_{\mathrm{pll}} - \omega_{\mathrm{ref,PLL}}$

The angle is frozen while the filtered voltage is below vPLL. The angle equation carries no base angular frequency, so kpPLL and kiPLL are in rad/s per pu. wrefPLL is also the initial value of $\omega_{\mathrm{pll}}$, so it cancels and has no effect on the response.

Network interface. The injected current is resolved with the PLL angle and rescaled to the system base:

$i_x = \left(I_{pf}\cos\theta_{\mathrm{pll}} + I_{qf}\sin\theta_{\mathrm{pll}}\right)\frac{S_{\mathrm{nom}}}{S_{\mathrm{base}}}, \qquad i_y = \left(I_{pf}\sin\theta_{\mathrm{pll}} - I_{qf}\cos\theta_{\mathrm{pll}}\right)\frac{S_{\mathrm{nom}}}{S_{\mathrm{base}}}$

A positive $I_{qf}$ injects reactive power. WT4 and BESS use the same interface.

Reactive power control modes. The flags combine as in the WECC specification:

Mode	PFFlag	vFlag	QFlag	RefFlag	QextFlag
Constant power factor	1	any	0	any	0
Constant Q	0	any	0	any	0
Local voltage control	0	0	1	any	0
Local coordinated Q/V control	0	1	1	any	0
Plant Q control	0	any	0	0	1
Plant voltage control	0	any	0	1	1
Plant voltage control + local coordinated Q/V	0	1	1	1	1
Plant Q control + local coordinated Q/V	0	1	1	0	1

Parameters

RAMSES applies no default values: a WT3 record must carry exactly 128 values, and one with more or fewer is refused. The Example column is the record in the usage example below. Per-unit values are on SNOM unless stated. The REPC_A, REEC_A, REGC_A and PLL blocks are the same code in WT4 at the indices given in the WT4 # column.

Rating and REPC_A plant controller

WT3 #	WT4 #	Name	Description	Unit	Example
1	1	SNOM	Rating, base of every per-unit quantity in the model	MVA	1.667
2	2	Rc	Compensation resistance	pu	0
3	3	Xc	Compensation reactance (droop or line-drop)	pu	0
4	4	vcompFlag	1: regulate $\lvert\bar v_{\mathrm{con}}\rvert$ (line-drop compensation); 0: regulate $v_t + K_c Q_{\mathrm{branch}}$ (droop)		0
5	5	Kc	Reactive droop gain (used when vcompFlag = 0)	pu/pu	0
6	6	Tfltr	Voltage and Q measurement filter; also the REGC_A voltage filter and the PLL input filter	s	0.02
7	7	RefFlag	1: voltage control; 0: reactive power control		1
8	8	dbd	Deadband on the V/Q error, symmetric, $\geq 0$	pu	0
9	9	emax	Upper limit on the V/Q error	pu	0.1
10	10	emin	Lower limit on the V/Q error	pu	-0.1
11	11	Kp	V/Q PI proportional gain	pu/pu	18
12	12	Ki	V/Q PI integral gain	pu/(pu·s)	5
13	13	Qmax	Upper limit of the V/Q PI	pu	0.44
14	14	Qmin	Lower limit of the V/Q PI	pu	-0.44
15	15	Tft	Lead time constant	s	0
16	16	Tfv	Lag time constant; below 0.005 the lead-lag is bypassed	s	0.05
17	17	vfrz	Voltage below which the V/Q integrator is frozen	pu	0.7
18	18	Tp	Filter on $P_{\mathrm{branch}}$; also the $P_e$ filter of WTGTRQ_A (WT3) and of the power-factor reference	s	0.05
19	19	fdbd1	Frequency deadband, lower edge, $\leq 0$	pu	-0.0006
20	20	fdbd2	Frequency deadband, upper edge, $\geq 0$	pu	0.0006
21	21	Ddn	Droop for over-frequency	pu/pu	20
22	22	Dup	Droop for under-frequency	pu/pu	0
23	23	femax	Upper limit on the power error	pu	999
24	24	femin	Lower limit on the power error	pu	-999
25	25	kpg	Power PI proportional gain	pu/pu	0.05
26	26	kig	Power PI integral gain	pu/(pu·s)	0.1
27	27	Pmax	Upper limit of the power PI	pu	1
28	28	Pmin	Lower limit of the power PI	pu	0
29	29	Tlag	Lag on the plant power output	s	0.1
30	30	FreqFlag	1: plant power loop sets $P_{\mathrm{refo}}$; 0: $P_{\mathrm{refo}}$ held at its initial value		0
31	31	Tmesf	Frequency measurement time constant, raised to 0.05 if smaller	s	0.02
32	32	QextFlag	1: plant V/Q loop sets $Q_{\mathrm{ext}}$; 0: $Q_{\mathrm{ext}}$ held at its initial value		0

With FreqFlag = 0 and QextFlag = 0, as in the example, REPC_A is computed but drives nothing.

WTGTRQ_A torque controller (WT3 only)

WT3 #	Name	Description	Unit	Example
33	Twref	Speed reference time constant	s	30
34	Kip	Torque PI integral gain	pu/(pu·s)	0.6
35	Kpp	Torque PI proportional gain	pu/pu	3
36	Temax	Maximum torque order	pu	1.2
37	Temin	Minimum torque order	pu	0
38	p1	Power-speed table, power of point 1	pu	0.2
39	spd1	Power-speed table, speed of point 1	pu	0.58
40	p2	Point 2, power	pu	0.4
41	spd2	Point 2, speed	pu	0.72
42	p3	Point 3, power	pu	0.6
43	spd3	Point 3, speed	pu	0.86
44	p4	Point 4, power	pu	0.8
45	spd4	Point 4, speed	pu	1.0
46	Tflag	1: PI on power error; 0: PI on speed error		1

WTGPT_A pitch controller (WT3 only)

WT3 #	Name	Description	Unit	Example
47	Kcc	Gain of the power error added to the speed error	pu/pu	0
48	Kiw	Pitch control integral gain	deg/(pu·s)	0.6
49	Kpw	Pitch control proportional gain	deg/pu	0.3
50	ThetaMin	Minimum pitch angle (also limits both PIs)	deg	0
51	ThetaMax	Maximum pitch angle (also limits both PIs)	deg	27
52	Ttheta	Pitch actuator time constant	s	0.3
53	Kic	Pitch compensation integral gain	deg/(pu·s)	0.6
54	Kpc	Pitch compensation proportional gain	deg/pu	3
55	dThetaMin	Minimum pitch rate	deg/s	-10
56	dThetaMax	Maximum pitch rate	deg/s	10

WTGAR_A aerodynamics and WTGT_A drivetrain (WT3 only; WT4 has its own drivetrain block, listed under WT4)

WT3 #	Name	Description	Unit	Example
57	Ka	Aerodynamic gain	pu/deg²	0.007
58	Thetao	Initial pitch angle $\theta_0$	deg	0
59	Ht	Turbine inertia	s	3.395
60	Hg	Generator inertia	s	0.962
61	Dshaft	Shaft damping	pu/pu	2.344
62	Kshaft	Shaft stiffness, per pu·s of twist	pu	1.387

REEC_A electrical controller

WT3 #	WT4 #	Name	Description	Unit	Example
63	38	vdip	Voltage below which a dip is declared	pu	0.9
64	39	vup	Voltage above which a dip is declared	pu	1.1
65	40	Trv	Terminal voltage filter	s	0.02
66	41	vref0	Reference for the dip injection; used as given, so 0 is not replaced by the initial voltage	pu	1
67	42	vref1	Bias added to $Q_r$ when vFlag = 0	pu	1
68	43	dbd1	Dip injection deadband, lower edge, $\leq 0$	pu	-0.05
69	44	dbd2	Dip injection deadband, upper edge, $\geq 0$	pu	0.05
70	45	kqv	Dip reactive current gain	pu/pu	2
71	46	Iqh1	Upper limit of the dip injection	pu	1.05
72	47	Iql1	Lower limit of the dip injection	pu	-1.05
73	48	qmax	Upper limit of $Q_r$	pu	0.44
74	49	qmin	Lower limit of $Q_r$	pu	-0.44
75	50	vmax	Upper limit of $V_{\mathrm{ref}}$ and of the Q PI	pu	1.1
76	51	vmin	Lower limit of $V_{\mathrm{ref}}$ and of the Q PI	pu	0.9
77	52	kqp	Q PI proportional gain	pu/pu	0
78	53	kqi	Q PI integral gain	pu/(pu·s)	0.1
79	54	kvp	V PI proportional gain	pu/pu	0
80	55	kvi	V PI integral gain	pu/(pu·s)	40
81	56	Tiq	Reactive current lag (QFlag = 0)	s	0.02
82	57	vq1	VDL1, voltage of point 1	pu	0.2
83	58	Iq1	VDL1, reactive current limit at point 1	pu	1
84	59	vq2	VDL1, point 2	pu	0.4
85	60	Iq2		pu	1
86	61	vq3	VDL1, point 3	pu	0.8
87	62	Iq3		pu	1
88	63	vq4	VDL1, point 4	pu	1
89	64	Iq4		pu	1
90	65	vp1	VDL2, voltage of point 1	pu	0.2
91	66	Ip1	VDL2, active current limit at point 1	pu	1
92	67	vp2	VDL2, point 2	pu	0.4
93	68	Ip2		pu	1
94	69	vp3	VDL2, point 3	pu	0.8
95	70	Ip3		pu	1
96	71	vp4	VDL2, point 4	pu	1
97	72	Ip4		pu	1
98	73	dPmax	Upper rate limit of $P_{\mathrm{ref}}$	pu/s	999
99	74	dPmin	Lower rate limit of $P_{\mathrm{ref}}$	pu/s	-999
100	75	pmax	Upper limit of $P_{\mathrm{ord}}$	pu	1
101	76	pmin	Lower limit of $P_{\mathrm{ord}}$	pu	0
102	77	Tpord	Power order lag	s	0.02
103	78	Imax	Converter current limit	pu	1.11
104	79	Thld	Post-dip hold of the reactive injection; its sign selects the mode	s	0
105	80	Thld2	Post-dip hold of $I_{p\max}$	s	0
106	81	Iqfrz	Reactive injection held after a dip when Thld $> 0$	pu	0
107	82	PFFlag	1: constant power factor; 0: reactive power reference $Q_{\mathrm{ext}}$		0
108	83	vFlag	1: $V_{\mathrm{ref}}$ from the Q PI; 0: $V_{\mathrm{ref}} = Q_r + v_{\mathrm{ref1}}$		0
109	84	QFlag	1: reactive current from the voltage PI; 0: from $Q_r/v_t$		0
110	85	PQFlag	1: active current priority; 0: reactive current priority		0
111	86	PFlag	1: power order is $P_{\mathrm{ref}}\,\omega_g$; 0: power order is $P_{\mathrm{ref}}$		1

REGC_A generator/converter and PLL

WT3 #	WT4 #	Name	Description	Unit	Example
112	87	Iqrmax	Reactive current rate limit, used when $Q_0 > 0$	pu/s	999
113	88	Iqrmin	Reactive current rate limit, used when $Q_0 < 0$	pu/s	-999
114	89	Tg	Converter current lag	s	0.02
115	90	vtmax	High-voltage threshold (WECC Volim)	pu	1.2
116	91	accel	High-voltage reactive current gain (WECC Khv)	pu/pu	0.7
117	92	QMIN	Lower limit of $I_q v_t$ less the high-voltage term (WECC Iolim)	pu	-1.3
118	93	lvpnt0	Active current is zero below this voltage	pu	0.4
119	94	lvpnt1	Active current is unreduced above this voltage	pu	0.8
120	95	Brkpt	Low-voltage power logic breakpoint	pu	0.9
121	96	zerox	Low-voltage power logic zero crossing	pu	0.4
122	97	Lvpl1	Low-voltage power logic limit at Brkpt	pu	1.22
123	98	Lvplsw	1: low-voltage power logic on; 0: off		0
124	99	rrpwr	Active current rise rate limit	pu/s	10
125	100	vPLL	Voltage below which the PLL angle is frozen	pu	0.2
126	101	kpPLL	PLL proportional gain	rad/s/pu	3
127	102	kiPLL	PLL integral gain	rad/s²/pu	30
128	103	wrefPLL	PLL frequency offset; cancels, no effect on the response		1

Time constants. A zero Tfltr, Tp, Tlag, Twref or Trv turns its block into a direct pass-through. Ttheta below 0.001 does the same for the pitch actuator but also removes every pitch limit, including those of the two PIs.

Caution

Keep Tiq, Tpord and Tg at 0.005 s or more, and Ht and Hg well above zero. Below that threshold RAMSES switches these blocks to an algebraic form that does not reduce to a pass-through: Tiq and Tpord then give half the intended value, and Tg breaks the active current channel.

Thirty-one further parameters are computed at initialization. Among them are the power-flow quantities vto, Peo, Qgeno and pfaref (the initial power factor angle, rad), the references Qextini, Prefini, vref, Qref and Plantpref held by REPC_A, and wo, the initial speed read off the power-speed table.

Observables

All quantities are in pu on SNOM.

Name	Description	Name	Description
Pe, Qgen	Terminal active and reactive power	wg, wt	Generator and turbine speed
vt	Terminal voltage	wref	Speed reference
Freq	Measured frequency	Pref	Torque order from WTGTRQ_A
vcon	Compensated voltage	Pord	Power order
Pbranch, Qbranch	Powers at the compensated point	Theta	Pitch angle (data unit, degrees by convention)
Prefo, Qext	Active and reactive references into WTGTRQ_A and REEC_A	Pm, Tm, Te	Mechanical power, mechanical and electrical torque
Plantpref, Qref, vref	REPC_A references, constant	Iqinj	Dip reactive current injection
Ipcmd, Iqcmd	Current commands	Ipmax, Iqmax, Iqmin	Current limits
Ipf, Iqf	Injected currents	x59	Low-voltage power logic limit on $I_p$; reads $10^9$ when inactive

Initialization

The model initializes from the power-flow voltage and injection: the PLL angle from the bus voltage angle, the converter currents by rotation into that frame, then every block backwards to its references. The mechanical side starts with $P_m = P_e$ and the speed read off the power-speed table.

RAMSES stops the simulation if the initial point violates the current limits or the dip thresholds: $I_{q\mathrm{cmd}}$ outside $\pm I_{q\max}$, $I_{p\mathrm{cmd}}$ outside $[0, I_{p\max}]$ (which also rejects a unit absorbing active power), or $v_t$ outside [vdip, vup]. No other limit is checked, so a PI or a lag can start on its limit without a warning. The initial voltage must also exceed lvpnt0.

Usage Example

A 1.667 MVA unit taking its whole operating point from the power flow (FP = FQ = 1), with the plant controller disconnected (FreqFlag = QextFlag = 0), constant reactive power and the drivetrain coupled to the output (PFlag = 1). This is the record of the 3-bus case in stepss-test-systems. Lines starting with # inside a record are ignored.

Show the data record

INJEC  WT3  DFIGB03  B03
      # FP FQ P Q: share of the power-flow injection (FP, FQ) or initial power (P in MW, Q in Mvar)
      1.  1.  0.  0.
      # SNOM: Rating, base of every per-unit quantity in the model (MVA)
      1.667
      # Rc: Compensation resistance (pu)
      0
      # Xc: Compensation reactance (droop or line-drop) (pu)
      0
      # vcompFlag: 1: regulate lvertbar v_conrvert (line-drop compensation); 0: regulate v_t + K_c Q_branch (droop)
      0
      # Kc: Reactive droop gain (used when vcompFlag = 0) (pu/pu)
      0
      # Tfltr: Voltage and Q measurement filter; also the REGC_A voltage filter and the PLL input filter (s)
      0.02
      # RefFlag: 1: voltage control; 0: reactive power control
      1
      # dbd: Deadband on the V/Q error, symmetric, geq 0 (pu)
      0
      # emax: Upper limit on the V/Q error (pu)
      0.1
      # emin: Lower limit on the V/Q error (pu)
      -0.1
      # Kp: V/Q PI proportional gain (pu/pu)
      18
      # Ki: V/Q PI integral gain (pu/(pu·s))
      5
      # Qmax: Upper limit of the V/Q PI (pu)
      0.44
      # Qmin: Lower limit of the V/Q PI (pu)
      -0.44
      # Tft: Lead time constant (s)
      0
      # Tfv: Lag time constant; below 0.005 the lead-lag is bypassed (s)
      0.05
      # vfrz: Voltage below which the V/Q integrator is frozen (pu)
      0.7
      # Tp: Filter on P_branch; also the P_e filter of WTGTRQ_A (WT3) and of the power-factor reference (s)
      0.05
      # fdbd1: Frequency deadband, lower edge, leq 0 (pu)
      -0.0006
      # fdbd2: Frequency deadband, upper edge, geq 0 (pu)
      0.0006
      # Ddn: Droop for over-frequency (pu/pu)
      20
      # Dup: Droop for under-frequency (pu/pu)
      0
      # femax: Upper limit on the power error (pu)
      999
      # femin: Lower limit on the power error (pu)
      -999
      # kpg: Power PI proportional gain (pu/pu)
      0.05
      # kig: Power PI integral gain (pu/(pu·s))
      0.1
      # Pmax: Upper limit of the power PI (pu)
      1
      # Pmin: Lower limit of the power PI (pu)
      0
      # Tlag: Lag on the plant power output (s)
      0.1
      # FreqFlag: 1: plant power loop sets P_refo; 0: P_refo held at its initial value
      0
      # Tmesf: Frequency measurement time constant, raised to 0.05 if smaller (s)
      0.02
      # QextFlag: 1: plant V/Q loop sets Q_ext; 0: Q_ext held at its initial value
      0
      # Twref: Speed reference time constant (s)
      30
      # Kip: Torque PI integral gain (pu/(pu·s))
      0.6
      # Kpp: Torque PI proportional gain (pu/pu)
      3
      # Temax: Maximum torque order (pu)
      1.2
      # Temin: Minimum torque order (pu)
      0
      # p1: Power-speed table, power of point 1 (pu)
      0.2
      # spd1: Power-speed table, speed of point 1 (pu)
      0.58
      # p2: Point 2, power (pu)
      0.4
      # spd2: Point 2, speed (pu)
      0.72
      # p3: Point 3, power (pu)
      0.6
      # spd3: Point 3, speed (pu)
      0.86
      # p4: Point 4, power (pu)
      0.8
      # spd4: Point 4, speed (pu)
      1
      # Tflag: 1: PI on power error; 0: PI on speed error
      1
      # Kcc: Gain of the power error added to the speed error (pu/pu)
      0
      # Kiw: Pitch control integral gain (deg/(pu·s))
      0.6
      # Kpw: Pitch control proportional gain (deg/pu)
      0.3
      # ThetaMin: Minimum pitch angle (also limits both PIs) (deg)
      0
      # ThetaMax: Maximum pitch angle (also limits both PIs) (deg)
      27
      # Ttheta: Pitch actuator time constant (s)
      0.3
      # Kic: Pitch compensation integral gain (deg/(pu·s))
      0.6
      # Kpc: Pitch compensation proportional gain (deg/pu)
      3
      # dThetaMin: Minimum pitch rate (deg/s)
      -10
      # dThetaMax: Maximum pitch rate (deg/s)
      10
      # Ka: Aerodynamic gain (pu/deg²)
      0.007
      # Thetao: Initial pitch angle theta_0 (deg)
      0
      # Ht: Turbine inertia (s)
      3.395
      # Hg: Generator inertia (s)
      0.962
      # Dshaft: Shaft damping (pu/pu)
      2.344
      # Kshaft: Shaft stiffness, per pu·s of twist (pu)
      1.387
      # vdip: Voltage below which a dip is declared (pu)
      0.9
      # vup: Voltage above which a dip is declared (pu)
      1.1
      # Trv: Terminal voltage filter (s)
      0.02
      # vref0: Reference for the dip injection; used as given, so 0 is not replaced by the initial voltage (pu)
      1
      # vref1: Bias added to Q_r when vFlag = 0 (pu)
      1
      # dbd1: Dip injection deadband, lower edge, leq 0 (pu)
      -0.05
      # dbd2: Dip injection deadband, upper edge, geq 0 (pu)
      0.05
      # kqv: Dip reactive current gain (pu/pu)
      2
      # Iqh1: Upper limit of the dip injection (pu)
      1.05
      # Iql1: Lower limit of the dip injection (pu)
      -1.05
      # qmax: Upper limit of the reactive power reference (pu)
      0.44
      # qmin: Lower limit of the reactive power reference (pu)
      -0.44
      # vmax: Upper limit of V_ref and of the Q PI (pu)
      1.1
      # vmin: Lower limit of V_ref and of the Q PI (pu)
      0.9
      # kqp: Q PI proportional gain (pu/pu)
      0
      # kqi: Q PI integral gain (pu/(pu·s))
      0.1
      # kvp: V PI proportional gain (pu/pu)
      0
      # kvi: V PI integral gain (pu/(pu·s))
      40
      # Tiq: Reactive current lag (QFlag = 0) (s)
      0.02
      # vq1: VDL1, voltage of point 1 (pu)
      0.2
      # Iq1: VDL1, reactive current limit at point 1 (pu)
      1
      # vq2: VDL1, point 2 (pu)
      0.4
      # Iq2:  (pu)
      1
      # vq3: VDL1, point 3 (pu)
      0.8
      # Iq3:  (pu)
      1
      # vq4: VDL1, point 4 (pu)
      1
      # Iq4:  (pu)
      1
      # vp1: VDL2, voltage of point 1 (pu)
      0.2
      # Ip1: VDL2, active current limit at point 1 (pu)
      1
      # vp2: VDL2, point 2 (pu)
      0.4
      # Ip2:  (pu)
      1
      # vp3: VDL2, point 3 (pu)
      0.8
      # Ip3:  (pu)
      1
      # vp4: VDL2, point 4 (pu)
      1
      # Ip4:  (pu)
      1
      # dPmax: Upper rate limit of P_ref (pu/s)
      999
      # dPmin: Lower rate limit of P_ref (pu/s)
      -999
      # pmax: Upper limit of the power order Pord (pu)
      1
      # pmin: Lower limit of the power order Pord (pu)
      0
      # Tpord: Power order lag (s)
      0.02
      # Imax: Converter current limit (pu)
      1.11
      # Thld: Post-dip hold of the reactive injection; its sign selects the mode (s)
      0
      # Thld2: Post-dip hold of I_pmax (s)
      0
      # Iqfrz: Reactive injection held after a dip when Thld > 0 (pu)
      0
      # PFFlag: 1: constant power factor; 0: reactive power reference Q_ext
      0
      # vFlag: 1: V_ref from the Q PI; 0: V_ref = Q_r + v_ref1
      0
      # QFlag: 1: reactive current from the voltage PI; 0: from Q_r/v_t
      0
      # PQFlag: 1: active current priority; 0: reactive current priority
      0
      # PFlag: 1: power order is P_ref,omega_g; 0: power order is P_ref
      1
      # Iqrmax: Reactive current rate limit, used when Q_0 > 0 (pu/s)
      999
      # Iqrmin: Reactive current rate limit, used when Q_0 < 0 (pu/s)
      -999
      # Tg: Converter current lag (s)
      0.02
      # vtmax: High-voltage threshold (WECC Volim) (pu)
      1.2
      # accel: High-voltage reactive current gain (WECC Khv) (pu/pu)
      0.7
      # QMIN: Lower limit of the converter reactive output after the high-voltage reduction (pu)
      -1.3
      # lvpnt0: Active current is zero below this voltage (pu)
      0.4
      # lvpnt1: Active current is unreduced above this voltage (pu)
      0.8
      # Brkpt: Low-voltage power logic breakpoint (pu)
      0.9
      # zerox: Low-voltage power logic zero crossing (pu)
      0.4
      # Lvpl1: Low-voltage power logic limit at Brkpt (pu)
      1.22
      # Lvplsw: 1: low-voltage power logic on; 0: off
      0
      # rrpwr: Active current rise rate limit (pu/s)
      10
      # vPLL: Voltage below which the PLL angle is frozen (pu)
      0.2
      # kpPLL: PLL proportional gain (rad/s/pu)
      3
      # kiPLL: PLL integral gain (rad/s²/pu)
      30
      # wrefPLL: PLL frequency offset; cancels, no effect on the response
      1
;

Note

With this record RAMSES reports INJECTORS NOT IN STEADY STATE at initialization. The residuals are on the Q and V PI controllers of REEC_A, which QFlag = 0 takes out of the loop, and whose initial values the model does not yet set consistently; one of their limiters also toggles during the first time step.

---

WT4 (inj_WT4): Type 4 Wind Turbine (Full Converter)

The data-file model name is WT4 (or inj_WT4).

Note

Available from RAMSES 3.50. The parameter list below has not changed since that release.

Description

A generic Type 4 (full converter) wind turbine. It is WT3 without the torque controller, the pitch controller and the aerodynamic block: the generator is decoupled from the grid by the converter, the mechanical torque is constant, and a two-mass drivetrain is kept only so that its torsional oscillations can appear in the output. Its WECC blocks, their approval status and the newer blocks RAMSES does not implement are listed under WECC Model Status.

Block	Role	WT4 #
SNOM	Rating, the per-unit base of the model	1
REPC_A	Plant controller, as in WT3	2–32
WTGT_A	Two-mass drivetrain	33–37
REEC_A	Electrical controller, as in WT3	38–86
REGC_A	Generator/converter interface, as in WT3	87–99
PLL	Angle of the injected current, as in WT3	100–103

REPC_A, REEC_A, REGC_A, the PLL and the network interface are the same code as in WT3, and their equations are given in the WT3 description. Every power, current and torque is in per unit on SNOM.

Scientific Description

WTGT_A, two-mass drivetrain. The mechanical torque is the constant $T_{mo} = P_{e0}/\omega_o$ and $T_e = P_e/\omega_g$:

$2H_t\frac{d\Delta\omega_t}{dt} = T_{mo} - K_{\mathrm{shaft}}\Delta\theta - D_{\mathrm{shaft}}(\Delta\omega_t - \Delta\omega_g)$

$2H_g\frac{d\Delta\omega_g}{dt} = K_{\mathrm{shaft}}\Delta\theta + D_{\mathrm{shaft}}(\Delta\omega_t - \Delta\omega_g) - T_e$

$\frac{d\Delta\theta}{dt} = \Delta\omega_t - \Delta\omega_g, \qquad \omega_g = \omega_o + \Delta\omega_g$

As in WT3, the twist equation carries no base angular frequency, so Kshaft is per pu·s of twist. Unlike WT3, the initial speed $\omega_o$ is a data parameter.

Coupling to the output. The drivetrain reaches the network only through PFlag. With PFlag = 1 the power order is $P_{\mathrm{ref}}\,\omega_g$, so a torsional oscillation of $\omega_g$ modulates the active current. With PFlag = 0 the drivetrain is still computed but has no effect on the injection. The active power reference $P_{\mathrm{ref}}$ is constant unless REPC_A drives it (FreqFlag = 1), and is rate-limited by dPmax and dPmin.

Parameters

RAMSES applies no default values: a WT4 record must carry exactly 103 values, and one with more or fewer is refused. Parameters 1–32 and 38–103 are listed in the parameter tables of WT3 under their WT4 #. The drivetrain block is specific to WT4:

WT4 #	Name	Description	Unit	Example
33	Ht	Turbine inertia	s	3.395
34	Hg	Generator inertia	s	0.962
35	wo	Initial generator speed, the reference of $\Delta\omega_g$	pu	1
36	Dshaft	Shaft damping	pu/pu	2.344
37	Kshaft	Shaft stiffness, per pu·s of twist	pu	1.387

The time-constant caution under the WT3 parameters applies here too.

Twenty-eight further parameters are computed at initialization, the same as WT3 less the mechanical ones, plus Tmo, the constant mechanical torque.

Observables

All quantities are in pu on SNOM.

Name	Description	Name	Description
Pe, Qgen	Terminal active and reactive power	wg	Generator speed
vt	Terminal voltage	Te	Electrical torque
Freq	Measured frequency	Tmo	Mechanical torque, constant
vcon	Compensated voltage	Iqinj	Dip reactive current injection
Pbranch, Qbranch	Powers at the compensated point	Ipcmd, Iqcmd	Current commands
Pref, Qext	Active and reactive references into REEC_A	Ipmax, Iqmax, Iqmin	Current limits
Plantpref, Qref, vref	REPC_A references, constant	Ip, Iq	Converter currents before the voltage management
pfaref	Initial power factor angle (rad), constant	Ipf, Iqf	Injected currents
		x59	Low-voltage power logic limit on $I_p$; reads $10^9$ when inactive

The initialization and its checks are those of WT3.

Usage Example

The WT3 example unit as a full converter: the same REPC_A, REEC_A, REGC_A and PLL values, with the drivetrain block in place of WTGTRQ_A, WTGPT_A, WTGAR_A and WTGT_A.

Show the data record

INJEC  WT4  WT4B03  B03
      # FP FQ P Q: share of the power-flow injection (FP, FQ) or initial power (P in MW, Q in Mvar)
      1.  1.  0.  0.
      # SNOM: Rating, base of every per-unit quantity in the model (MVA)
      1.667
      # Rc: Compensation resistance (pu)
      0
      # Xc: Compensation reactance (droop or line-drop) (pu)
      0
      # vcompFlag: 1: regulate lvertbar v_conrvert (line-drop compensation); 0: regulate v_t + K_c Q_branch (droop)
      0
      # Kc: Reactive droop gain (used when vcompFlag = 0) (pu/pu)
      0
      # Tfltr: Voltage and Q measurement filter; also the REGC_A voltage filter and the PLL input filter (s)
      0.02
      # RefFlag: 1: voltage control; 0: reactive power control
      1
      # dbd: Deadband on the V/Q error, symmetric, geq 0 (pu)
      0
      # emax: Upper limit on the V/Q error (pu)
      0.1
      # emin: Lower limit on the V/Q error (pu)
      -0.1
      # Kp: V/Q PI proportional gain (pu/pu)
      18
      # Ki: V/Q PI integral gain (pu/(pu·s))
      5
      # Qmax: Upper limit of the V/Q PI (pu)
      0.44
      # Qmin: Lower limit of the V/Q PI (pu)
      -0.44
      # Tft: Lead time constant (s)
      0
      # Tfv: Lag time constant; below 0.005 the lead-lag is bypassed (s)
      0.05
      # vfrz: Voltage below which the V/Q integrator is frozen (pu)
      0.7
      # Tp: Filter on P_branch and on the power-factor reference (s)
      0.05
      # fdbd1: Frequency deadband, lower edge, leq 0 (pu)
      -0.0006
      # fdbd2: Frequency deadband, upper edge, geq 0 (pu)
      0.0006
      # Ddn: Droop for over-frequency (pu/pu)
      20
      # Dup: Droop for under-frequency (pu/pu)
      0
      # femax: Upper limit on the power error (pu)
      999
      # femin: Lower limit on the power error (pu)
      -999
      # kpg: Power PI proportional gain (pu/pu)
      0.05
      # kig: Power PI integral gain (pu/(pu·s))
      0.1
      # Pmax: Upper limit of the power PI (pu)
      1
      # Pmin: Lower limit of the power PI (pu)
      0
      # Tlag: Lag on the plant power output (s)
      0.1
      # FreqFlag: 1: plant power loop sets P_refo; 0: P_refo held at its initial value
      0
      # Tmesf: Frequency measurement time constant, raised to 0.05 if smaller (s)
      0.02
      # QextFlag: 1: plant V/Q loop sets Q_ext; 0: Q_ext held at its initial value
      0
      # Ht: Turbine inertia (s)
      3.395
      # Hg: Generator inertia (s)
      0.962
      # wo: Initial generator speed, the reference of Deltaomega_g (pu)
      1
      # Dshaft: Shaft damping (pu/pu)
      2.344
      # Kshaft: Shaft stiffness, per pu·s of twist (pu)
      1.387
      # vdip: Voltage below which a dip is declared (pu)
      0.9
      # vup: Voltage above which a dip is declared (pu)
      1.1
      # Trv: Terminal voltage filter (s)
      0.02
      # vref0: Reference for the dip injection; used as given, so 0 is not replaced by the initial voltage (pu)
      1
      # vref1: Bias added to Q_r when vFlag = 0 (pu)
      1
      # dbd1: Dip injection deadband, lower edge, leq 0 (pu)
      -0.05
      # dbd2: Dip injection deadband, upper edge, geq 0 (pu)
      0.05
      # kqv: Dip reactive current gain (pu/pu)
      2
      # Iqh1: Upper limit of the dip injection (pu)
      1.05
      # Iql1: Lower limit of the dip injection (pu)
      -1.05
      # qmax: Upper limit of the reactive power reference (pu)
      0.44
      # qmin: Lower limit of the reactive power reference (pu)
      -0.44
      # vmax: Upper limit of V_ref and of the Q PI (pu)
      1.1
      # vmin: Lower limit of V_ref and of the Q PI (pu)
      0.9
      # kqp: Q PI proportional gain (pu/pu)
      0
      # kqi: Q PI integral gain (pu/(pu·s))
      0.1
      # kvp: V PI proportional gain (pu/pu)
      0
      # kvi: V PI integral gain (pu/(pu·s))
      40
      # Tiq: Reactive current lag (QFlag = 0) (s)
      0.02
      # vq1: VDL1, voltage of point 1 (pu)
      0.2
      # Iq1: VDL1, reactive current limit at point 1 (pu)
      1
      # vq2: VDL1, point 2 (pu)
      0.4
      # Iq2:  (pu)
      1
      # vq3: VDL1, point 3 (pu)
      0.8
      # Iq3:  (pu)
      1
      # vq4: VDL1, point 4 (pu)
      1
      # Iq4:  (pu)
      1
      # vp1: VDL2, voltage of point 1 (pu)
      0.2
      # Ip1: VDL2, active current limit at point 1 (pu)
      1
      # vp2: VDL2, point 2 (pu)
      0.4
      # Ip2:  (pu)
      1
      # vp3: VDL2, point 3 (pu)
      0.8
      # Ip3:  (pu)
      1
      # vp4: VDL2, point 4 (pu)
      1
      # Ip4:  (pu)
      1
      # dPmax: Upper rate limit of P_ref (pu/s)
      999
      # dPmin: Lower rate limit of P_ref (pu/s)
      -999
      # pmax: Upper limit of the power order Pord (pu)
      1
      # pmin: Lower limit of the power order Pord (pu)
      0
      # Tpord: Power order lag (s)
      0.02
      # Imax: Converter current limit (pu)
      1.11
      # Thld: Post-dip hold of the reactive injection; its sign selects the mode (s)
      0
      # Thld2: Post-dip hold of I_pmax (s)
      0
      # Iqfrz: Reactive injection held after a dip when Thld > 0 (pu)
      0
      # PFFlag: 1: constant power factor; 0: reactive power reference Q_ext
      0
      # vFlag: 1: V_ref from the Q PI; 0: V_ref = Q_r + v_ref1
      0
      # QFlag: 1: reactive current from the voltage PI; 0: from Q_r/v_t
      0
      # PQFlag: 1: active current priority; 0: reactive current priority
      0
      # PFlag: 1: power order is P_ref,omega_g; 0: power order is P_ref
      1
      # Iqrmax: Reactive current rate limit, used when Q_0 > 0 (pu/s)
      999
      # Iqrmin: Reactive current rate limit, used when Q_0 < 0 (pu/s)
      -999
      # Tg: Converter current lag (s)
      0.02
      # vtmax: High-voltage threshold (WECC Volim) (pu)
      1.2
      # accel: High-voltage reactive current gain (WECC Khv) (pu/pu)
      0.7
      # QMIN: Lower limit of the converter reactive output after the high-voltage reduction (pu)
      -1.3
      # lvpnt0: Active current is zero below this voltage (pu)
      0.4
      # lvpnt1: Active current is unreduced above this voltage (pu)
      0.8
      # Brkpt: Low-voltage power logic breakpoint (pu)
      0.9
      # zerox: Low-voltage power logic zero crossing (pu)
      0.4
      # Lvpl1: Low-voltage power logic limit at Brkpt (pu)
      1.22
      # Lvplsw: 1: low-voltage power logic on; 0: off
      0
      # rrpwr: Active current rise rate limit (pu/s)
      10
      # vPLL: Voltage below which the PLL angle is frozen (pu)
      0.2
      # kpPLL: PLL proportional gain (rad/s/pu)
      3
      # kiPLL: PLL integral gain (rad/s²/pu)
      30
      # wrefPLL: PLL frequency offset; cancels, no effect on the response
      1
;

Note

With this record, as with the WT3 one, RAMSES reports INJECTORS NOT IN STEADY STATE at initialization. The residuals are on the Q and V PI controllers of REEC_A, which QFlag = 0 takes out of the loop, and whose initial values the model does not yet set consistently; one of their limiters also toggles during the first time step.

---

BESS (inj_BESS): Battery Energy Storage System

The data-file model name is BESS (or inj_BESS).

Description

A comprehensive BESS model implementing the full WECC framework (REPC_A + REEC_C + REGC_A) plus battery state of charge (SOC) tracking. The model supports both grid-following operation (bidirectional active power dispatch) and reactive power / voltage regulation. It is built on the same REPC_A plant controller as the wind turbine models, and uses the REEC_C converter electrical controller which handles a piecewise-linear $I_q$-vs-$V$ and $I_p$-vs-$V$ characteristic for fault ride-through.

The battery SOC evolves through integration of injected power:

$\frac{d\mathrm{SOC}}{dt} = -\frac{P_{\mathrm{bess}}}{C_{\mathrm{bat}} \cdot S_{\mathrm{nom}}}$

with hard clamps at SOCmin and SOCmax that modify the active power limits Pmax/Pmin dynamically:

$P_{\max} = \begin{cases} 0 & \mathrm{SOC} \ge \mathrm{SOC}_{\max}\\ P_{\max,\mathrm{rated}} & \text{otherwise}\end{cases}$

$P_{\min} = \begin{cases} 0 & \mathrm{SOC} \le \mathrm{SOC}_{\min}\\ P_{\min,\mathrm{rated}} & \text{otherwise}\end{cases}$

Parameters (key parameters)

#	Name	Sub-model	Description	Unit
1	SNOM		Nominal power	MW
2–32		REPC_A	Plant controller (same as WT3/WT4)	various
33–76		REEC_C	Electrical controller with piecewise $I_q(V)$, $I_p(V)$	various
68	CapBat	BESS	Battery energy capacity	MWh
69	SOCini	BESS	Initial state of charge	pu
70	SOCmax	BESS	Maximum SOC limit	pu
71	SOCmin	BESS	Minimum SOC limit	pu
72–73	dPmax, dPmin	BESS	Active power ramp rate limits	pu/s
74–75	pmax, pmin	REEC_C	Active current limits (pu on SNOM)	pu
76	Tpord	REEC_C	Active power order time constant	s

Full parameter listing has approximately 125 parameters; refer to a working example data file for the complete ordering.

State Variables

The BESS model uses over 40 internal states reflecting the three sub-models. Key states include:

Variable	Description
SOC	State of charge
Pref	Active power reference
Qext	Reactive power reference from REPC_A
Ip, Iq	Active/reactive current outputs
PLLPhaseAngle	PLL phase angle
Pgen, Qgen	Generated powers

Usage Example

Show the data record

INJEC  BESS  BESS1  BUS_ST
      # FP FQ P Q: share of the power-flow injection (FP, FQ) or initial power (P in MW, Q in Mvar)
      1.  1.  0.  0.
      # SNOM: Rating, base of every per-unit quantity in the model (MVA)
      100.
      # Rc: Compensation resistance (pu)
      0
      # Xc: Compensation reactance (droop or line-drop) (pu)
      0
      # vcompFlag: 1: regulate lvertbar v_conrvert (line-drop compensation); 0: regulate v_t + K_c Q_branch (droop)
      0
      # Kc: Reactive droop gain (used when vcompFlag = 0) (pu/pu)
      0
      # Tfltr: Voltage and Q measurement filter; also the REGC_A voltage filter and the PLL input filter (s)
      0.02
      # RefFlag: 1: voltage control; 0: reactive power control
      1
      # dbd: Deadband on the V/Q error, symmetric, geq 0 (pu)
      0
      # emax: Upper limit on the V/Q error (pu)
      0.1
      # emin: Lower limit on the V/Q error (pu)
      -0.1
      # Kp: V/Q PI proportional gain (pu/pu)
      18
      # Ki: V/Q PI integral gain (pu/(pu·s))
      5
      # Qmax: Upper limit of the V/Q PI (pu)
      0.44
      # Qmin: Lower limit of the V/Q PI (pu)
      -0.44
      # Tft: Lead time constant (s)
      0
      # Tfv: Lag time constant; below 0.005 the lead-lag is bypassed (s)
      0.05
      # vfrz: Voltage below which the V/Q integrator is frozen (pu)
      0.7
      # Tp: Filter on P_branch and on the power-factor reference (s)
      0.05
      # fdbd1: Frequency deadband, lower edge, leq 0 (pu)
      -0.0006
      # fdbd2: Frequency deadband, upper edge, geq 0 (pu)
      0.0006
      # Ddn: Droop for over-frequency (pu/pu)
      20
      # Dup: Droop for under-frequency (pu/pu)
      0
      # femax: Upper limit on the power error (pu)
      999
      # femin: Lower limit on the power error (pu)
      -999
      # kpg: Power PI proportional gain (pu/pu)
      0.05
      # kig: Power PI integral gain (pu/(pu·s))
      0.1
      # Pmax: Upper limit of the power PI (pu)
      1
      # Pmin: Lower limit of the power PI (pu)
      -1
      # Tlag: Lag on the plant power output (s)
      0.1
      # FreqFlag: 1: plant power loop sets P_refo; 0: P_refo held at its initial value
      0
      # Tmesf: Frequency measurement time constant, raised to 0.05 if smaller (s)
      0.02
      # QextFlag: 1: plant V/Q loop sets Q_ext; 0: Q_ext held at its initial value
      0
      # vdip: Voltage below which a dip is declared (pu)
      0.9
      # vup: Voltage above which a dip is declared (pu)
      1.1
      # Trv: Terminal voltage filter (s)
      0.02
      # vref0: Reference for the dip injection; used as given, so 0 is not replaced by the initial voltage (pu)
      1
      # dbd1: Dip injection deadband, lower edge, leq 0 (pu)
      -0.05
      # dbd2: Dip injection deadband, upper edge, geq 0 (pu)
      0.05
      # kqv: Dip reactive current gain (pu/pu)
      2
      # Iqh1: Upper limit of the dip injection (pu)
      1.05
      # Iql1: Lower limit of the dip injection (pu)
      -1.05
      # qmax: Upper limit of the reactive power reference (pu)
      0.44
      # qmin: Lower limit of the reactive power reference (pu)
      -0.44
      # vmax: Upper limit of V_ref and of the Q PI (pu)
      1.1
      # vmin: Lower limit of V_ref and of the Q PI (pu)
      0.9
      # kqp: Q PI proportional gain (pu/pu)
      0
      # kqi: Q PI integral gain (pu/(pu·s))
      0.1
      # kvp: V PI proportional gain (pu/pu)
      0
      # kvi: V PI integral gain (pu/(pu·s))
      40
      # Tiq: Reactive current lag (QFlag = 0) (s)
      0.02
      # vq1: VDL1, voltage of point 1 (pu)
      0.2
      # Iq1: VDL1, reactive current limit at point 1 (pu)
      1
      # vq2: VDL1, point 2 (pu)
      0.4
      # Iq2:  (pu)
      1
      # vq3: VDL1, point 3 (pu)
      0.8
      # Iq3:  (pu)
      1
      # vq4: VDL1, point 4 (pu)
      1
      # Iq4:  (pu)
      1
      # vp1: VDL2, voltage of point 1 (pu)
      0.2
      # Ip1: VDL2, active current limit at point 1 (pu)
      1
      # vp2: VDL2, point 2 (pu)
      0.4
      # Ip2:  (pu)
      1
      # vp3: VDL2, point 3 (pu)
      0.8
      # Ip3:  (pu)
      1
      # vp4: VDL2, point 4 (pu)
      1
      # Ip4:  (pu)
      1
      # Paux: Constant added to the active current command after dividing Pord by voltage (Ipcmd = Pord/V + Paux), on SNOM base (pu)
      0.
      # CapBat: Battery energy capacity (MWh)
      100.
      # SOCini: Initial state of charge as a fraction of CapBat; must lie strictly between SOCmin and SOCmax (pu)
      0.5
      # SOCmax: Upper SOC limit; at it the battery is full and charging current is blocked (Ipmin = 0) (pu)
      0.9
      # SOCmin: Lower SOC limit; at it the battery is empty and discharging current is blocked (Ipmax = 0) (pu)
      0.1
      # dPmax: Upper rate limit of P_ref (pu/s)
      999
      # dPmin: Lower rate limit of P_ref (pu/s)
      -999
      # pmax: Upper limit of the power order Pord (pu)
      1
      # pmin: Lower limit of the power order Pord (pu)
      -1
      # Tpord: Active power order time constant (s)
      0.02
      # Imax: Converter current limit (pu)
      1.11
      # PFFlag: 1: constant power factor; 0: reactive power reference Q_ext
      0
      # vFlag: 1: V_ref from the Q PI; 0: V_ref = Q_r + v_ref1
      0
      # QFlag: 1: reactive current from the voltage PI; 0: from Q_r/v_t
      0
      # PQFlag: 1: active current priority; 0: reactive current priority
      0
      # Iqrmax: Reactive current rate limit, used when Q_0 > 0 (pu/s)
      999
      # Iqrmin: Reactive current rate limit, used when Q_0 < 0 (pu/s)
      -999
      # Tg: Converter current lag (s)
      0.02
      # vtmax: High-voltage threshold (WECC Volim) (pu)
      1.2
      # accel: High-voltage reactive current gain (WECC Khv) (pu/pu)
      0.7
      # QMIN: Lower limit of the converter reactive output after the high-voltage reduction (pu)
      -1.3
      # lvpnt0: Active current is zero below this voltage (pu)
      0.4
      # lvpnt1: Active current is unreduced above this voltage (pu)
      0.8
      # Brkpt: Low-voltage power logic breakpoint (pu)
      0.9
      # zerox: Low-voltage power logic zero crossing (pu)
      0.4
      # Lvpl1: Low-voltage power logic limit at Brkpt (pu)
      1.22
      # Lvplsw: 1: low-voltage power logic on; 0: off
      0
      # rrpwr: Active current rise rate limit (pu/s)
      10
      # vPLL: Voltage below which the PLL angle is frozen (pu)
      0.2
      # kpPLL: PLL proportional gain (rad/s/pu)
      3
      # kiPLL: PLL integral gain (rad/s²/pu)
      30
      # wrefPLL: PLL frequency offset; cancels, no effect on the response
      1
;