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Guideline for PSSE Stability Modeling of Inverter-Based DER ≥ 5 MW

to Meet National Grid SRD for Western RI DER ASO 3(applicable to PSSE V34)

The following generic renewable energy system modules from the PSS/E Rev 34.8.1 Standard Library

models shall be used to represent the transient stability characteristics of the inverter-based DERs.

1.) Renewable Energy Generator/Converter Model:

REGC_B

2.) Renewable Energy Electrical Model:

REEC_D

3.) Power Plant Controller model:

REPC_A -- (for Stand-Alone PV, Stand-Alone BESS, and DC coupled PV+BESS)

PLNTBU1 + REAX4BU1 – (For AC coupled PV+BESS)

The sections below provide guidelines for parameterizing these generic PSS/E renewable energy system

models to comply with various performance requirements outlined in the Source Requirements

Document (SRD) for the Western RI DER ASO 3 Study (refer to National Grid SRD_Western RI ASO3.pdf).

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REGC_B Model Guidelines - Model parameters are to be provided in per unit of machine MVA base.

Parameter DescriptionTypical Value

or range ofValues*

Comments

RateFlagRateFlag switch;0: rate limit on active current,1: rate limit on active power

0 or 1 Inverter specific

PQ PriorityFlag

PQ priority Flag;0: Q priority,1: P priority

0 or 1

Needs to be consistent with the PQFlag ofassociated REEC_D model

Set to 0 (Q Priority), if providing dynamicvoltage support in the mandatory operationregion of attached SRD document

Set to 1 (P Priority), if not providing dynamicvoltage support in the mandatory operationregion of attached SRD document

TgLag time constant emulating currentregulator response time. [s]

0.017 to 0.03 Cannot be zero

TeLag time constant representing delayin converter firing controls. [s].

0.01 to 0.017 Should generally not set this to zero

TfltrLag time constant representing the lagin the terminal voltage measurementtransducer [s]

0.02 to 0.05 Can be set to zero

Rrpwr

Rate limit on active power recoveryrate after a large voltage dip, orsudden change in active powercommand. [p.u/s]

2 to 20

Ramp rate for active current recovery needsto be at least 2 p.u/s since IEEE 1547requires DERs to restore output to at least80% within 0.4 seconds. Please provide theinverter’s actual ramp rate.

Re Equivalent source resistance. [p.u] 0 to 0.02

Re is a Loadflow model parameter, not astability model parameter. Please provideseparately in the load flow model.Re is typically set to zero

Xe Equivalent source reactance. [p.u] 0.05 to 0.3

Xe is a Loadflow model parameter, not astability model parameterPlease provide separately in the load flowmodel.

Iqrmax

Rate limit on reactive current recoveryafter a fault if the initial reactivecurrent is positive (injecting into thegrid).

1 to 999

Parameter value is irrelevant because initialreactive current is always zero (DER notallowed to control voltage under normaloperating conditions (i.e. “steady state)

Iqrmin

Rate limit on reactive current recoveryafter a fault if the initial reactivecurrent is negative (absorbing fromthe grid).

-1 to -999

Parameter value irrelevant because initialreactive current is always zero (DER notallowed to control voltage under normaloperating conditions (i.e. “steady state)

Imax Maximum converter current limit [p.u] 1.0 to 1.5

Needs to be consistent with the associatedREEC_D modelPlease provide inverter’s maximum currentcapability.

*Typical values are provided only for guidance and should not be interpreted as a strict range of

numbers.

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REEC_D Model Guidelines - Model parameters are to be provided in per unit of machine MVA base.

Parameter DescriptionTypical Value

or range ofValues*

Comments

PFFLAG• 1 if power factor control• 0 if Q control (which can be controlledby an external signal)

0 or 1Set to 0. DERs not allowed to controlvoltage under normal operating conditions.

VFLAG• 1 if Q control• 0 if voltage control

0 or 1Set to 0 or 1. VFLAG value is irrelevant ifQFLAG is set to zero

QFLAG• 1 if voltage or Q control• 0 if constant pf or Q control

0 or 1Set to 0. DERs not allowed to controlvoltage under normal operating conditions

PFLAG• 1 if active current command has speeddependency• 0 for no dependency

0 or 1Set to 0. No speed dependency for PV orBESS.

PQFLAGP/Q priority flag for current limit:• 0 for Q priority• 1 for P priority

0 or 1

Needs to be consistent with PQFlag ofassociated REGC_B model

Set to 0 (Q Priority), if providing dynamicvoltage support in the mandatory operationregion of attached SRD document

Set to 1 (P Priority), if not providing dynamicvoltage support in the mandatory operationregion of attached SRD document

VcmpFlag:• 1 for current compensation• 0 for reactive droop compensation

0 or 1Setting is irrelevant, since Qflag set to 0.DERs not allowed to control voltage undernormal operating conditions.

Vdip (pu)low voltage threshold to activatereactive current injectionlogic

<0.90

Set to 0.88pu, if providing dynamic voltagesupport in the low voltage, mandatoryoperation region of attached SRD document

Set to < 0.50, if not providing dynamicvoltage support in the low voltage,mandatory operation region of attachedSRD document

Vup (pu)Voltage above which reactive currentinjection logic is activated

> 1.10Set above 1.2 so as not to provide dynamicvoltage support in the continuous operationregion of attached SRD document

Trv (s) Voltage filter time constant 0.02 to 0.05Inverter specific. Needs to be the same asTfltr in REGC_B model.

dbd1 (pu)Voltage error dead band lowerthreshold (≤0)

-0.1 to 0Enter inverter specific values if inverter isproviding dynamic voltage support in in thelow voltage, mandatory operation region ofattached SRD document.

Otherwise, parameter values are irrelevant.

dbd2 (pu)Voltage error dead band upperthreshold (≥0)

0 to 0.1

Kqv (pu)Reactive current injection gain duringover and undervoltage conditions

0 to 10

Iqh1 (pu),Upper limit on reactive current injectionIqinj

1 to 1.1

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Parameter DescriptionTypical Value

or range ofValues*

Comments

Iql1 (pu),Lower limit on reactive current injectionIqinj

-1.1 to 1

Vref0 (pu),User defined reference (if 0, modelinitializes it to initial terminal voltage)

0.95 to 1.05

IqfrzValue to which reactive-currentcommand is frozen after a voltage-dip[p.u]

0

Thld

Time for which reactive-currentcommand is frozen after a voltage-dip[s]; if positive then Iqcmd is frozen to itsfinal value during the voltage-dip; ifnegative then Iqcmd is frozen to Iqfrz

0

Thld2Time for which Ipcmdbl (value of Ipcmdbefore limit) is frozen after the voltagedip is over (s)

0 inverter specific

TpFilter time constant for electrical power(s),

0.01 to 0.1 inverter specific

QMaxThe maximum value of the incomingQext or Vext [p.u]

0.4 to 1.0Set to 0. Inverter not allowed to controlvoltage under normal operating conditions

QMinThe minimum value of the incomingQext or Vext [p.u]

-1.0 to -0.4Set to 0. Inverter not allowed to controlvoltage under normal operating conditions

VMAX Maximum limit for voltage control [p.u] 1.05 to 1.1

Parameter values are irrelevant, since QFlagset to 0. DERs not allowed to controlvoltage under normal operating conditions

VMIN Minimum limit for voltage control [p.u] 0.9 to 0.95

KqpReactive power regulator proportionalgain (p.u)

N/A

KqiReactive power regulator integral gain(p.u)

N/A

KvpVoltage regulator proportional gain(p.u)

N/A

Kvi Voltage regulator integral gain (p.u) N/A

Vbias User-defined bias (p.u) normally 0Parameter value irrelevant, since VFlag setto 1.

Tiq Time constant on delay for block s4 (s) 0.02 – 0.05 inverter specific

dPmaxPower reference maximum ramp rate(p.u/s)

>0 Must be greater than 0

dPminPower reference minimum ramp rate(p.u/s)

<0 Must be less than 0

PMAX Maximum power limit (p.u) 1

PMIN Minimum power limit (p.u) 0

ImaxMaximum limit on total convertercurrent (p.u)

1.0 to 1.5 Must match Imax value in REGC_B model

Tpord Power filter time constant (s) 0.02 to 0.05

VDL vq-iq10 pairs of values defining the voltagedependent reactive-current limits [p.u]

N/A

Enter Inverter specific values if inverteremploys Voltage Dependent Limits forreactive current. Otherwise, set all VDL vq-iqdata to zero

VDL vp-ip10 pairs of values defining the voltagedependent active-current limits [p.u]

N/A

Enter Inverter specific values if inverteremploys Voltage Dependent Limits for activecurrent. Otherwise, set all VDL vp-ip data tozero

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Parameter DescriptionTypical Value

or range ofValues*

Comments

rc Current-compensation resistance [p.u] 0 to 0.02

Parameter values are irrelevant, since QFlagset to 0. DERs not allowed to controlvoltage under normal operating conditions

Xc Current-compensation reactance [p.u] 0.01 to 0.12

Tr1Filter time constant for voltagemeasurement. Can be set to “zero”. [s]

0.02 to 0.05

Kc Reactive-current compensation gain 0.01 to 0.05

Ke Scaling on Ipmin; 0 to 1set to 0 for a generator,set to a value between 0 and 1 for a storagedevice, as appropriate

vblklVoltage below which the converter isblocked (i.e. Iq = Ip = 0)

0.50 p.uSet to 0.50 p.u to correctly modelMomentary Cessation low voltage thresholdper attached SRD document

vblkhVoltage above which the converter isblocked (i.e. Iq = Ip = 0)

1.1 p.uSet to 1.10 p.u to correctly modelMomentary Cessation high voltagethreshold per attached SRD document

Tblk_delayThe time delay following blocking of theconverter after which the converter isreleased from being blocked

0.04 to 0.1Time delay after release from converterblocking due to Momentary cessation.

*Typical values are provided only for guidance and should not be interpreted as a strict range of numbers.

Where N/A is listed, this indicates that there is no typical range to be provided.

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REPC_A Model Guidelines – To be used for stand-Alone PV, stand-Alone BESS, and DC coupled

PV+BESS

Model parameters are to be provided in per unit of machine MVA base.

Parameter DescriptionTypical Value

or range ofValues*

Comments

VCFLAG Droop flag for Voltage control 0 or 1 Set to 0 or 1. Irrelevant if RefFlag is set to 0

RefFlag Flag for Voltage or Q control 0 or 1Set to 0. No voltage control allowed forcontinuous operation.

Fflag Frequency Control Flag 0 or 1Set to 1, Enable frequency response, perattached SRD document

tfltrVoltage and reactive power filtertime constant, sec.

0.02 to 0.05

Parameter values are irrelevant, DERs notallowed to control voltage under normaloperating conditions

kpVolt/VAr regulator proportionalgain, p.u.

-

kiVolt/VAr regulator integral gain,p.u.

-

tftPlant controller Q output lead timeconstant, sec.

0

tfvPlant controller Q output lag timeconstant, sec.

0.02 to 0.15

vfrzVoltage for freezing Volt/VArregulator integrator, p.u.

0.00 to 0.90

rcLine drop compensationresistance, p.u.

0.0

xcLine drop compensation reactance,p.u.

0.0

kc Reactive droop gain, p.u. -

emax Maximum Volt/VAr error, p.u. -999

emin Minimum Volt/VAr error, p.u. 999

Dbd1Lower threshold for reactive powercontrol deadband (<=0)

<=0

Dbd1Upper threshold for reactive powercontrol deadband (>=0)

>=0

QmaxMaximum plant reactive powercommand, p.u.

0.00 to 0.43Set to 0. No voltage control allowed forcontinuous operation

QminMinimum plant reactive powercommand, p.u.

-0.43 to 0.00Set to 0. No voltage control allowed forcontinuous operation.

kpgReal power control proportionalgain, p.u.

- PPC specific

kigReal power control integral gain,p.u.

- PPC specific

tpActive power filter time constant,sec.

0.02 to 0.05 PPC specific

fdbd1Frequency deadband downside,p.u.

-0.01 to 0.00Set to - 0.0006 p.u. 0.036 Hz deadband isrequired per attached SRD (0.036Hz/60Hz)

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Parameter DescriptionTypical Value

or range ofValues*

Comments

fdbd2 Frequency deadband upside, p.u. 0.00 to 0.01Set to 0.0006 p.u. 0.036 hz deadband isrequired per attached SRD (0.036Hz/60Hz)

femaxMaximum power error in droopregulator, p.u.

-999

feminMinimum power error in droopregulator, p.u.

999

pmaxMaximum plant active powercommand, p.u.

1

pminMinimum plant active powercommand, p.u.

0 or -1

Set to 0 if Stand-Alone PV.Set to -1 if stand-alone BESS.

If DC coupled PV+BESSSet to negative of BESS MW rating,in p.u of PV MW rating, if PV MWrating larger than BESS MW rating

Otherwise, set to – 1.

tgPlant controller P output lag timeconstant, sec.

0.02 to 0.15 PPC specific

ddnReciprocal of down regulationdroop, p.u.

0.00 to 33.33Set to 20. 5% droop setting is required perattached SRD document.

dupReciprocal of up regulation droop,p.u.

0.00 to 33.33

Set to 20 if stand-alone BESS or DC CoupledPV+BESS. 5% droop setting is required perattached SRD document.

Otherwise, set to 0.

*Typical values are provided only for guidance and should not be interpreted as a strict range of numbers.

Where N/A is listed, this indicates that there is no typical range to be provided.

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PLNTBU1 Model Guidelines – To be used for AC coupled PV+BESS

Note: REAX4BU1 Model is also required to be used with PLNTBU1 (see later in document)

Model parameters are to be provided in per unit of system MVA base (100 MVA).

Parameter DescriptionTypical Value

or range ofValues*

Comments

VCFLAG Droop flag for Voltage control 0 or 1 Set to 0 or 1. Irrelevant if RefFlag is set to 0

RefFlag Flag for Voltage or Q control 0 or 1Set to 0. No voltage control allowed forcontinuous operation.

Fflag Freqency Control Flag 0 or 1Set to 1, Enable frequency response, perattached SRD document

tfltrVoltage and reactive power filtertime constant, sec.

0.02 to 0.05

Parameter values are irrelevant, DERs notallowed to control voltage under normaloperating conditions

kpVolt/VAr regulator proportionalgain, p.u.

-

kiVolt/VAr regulator integral gain,p.u.

-

tftPlant controller Q output lead timeconstant, sec.

0

tfvPlant controller Q output lag timeconstant, sec.

0.02 to 0.15

vfrzVoltage for freezing Volt/VArregulator integrator, p.u.

0.00 - 0.90

rcLine drop compensationresistance, p.u.

0.0

xcLine drop compensation reactance,p.u.

0.0

kc Reactive droop gain, p.u. -

emax Maximum Volt/VAr error, p.u. -999

emin Minimum Volt/VAr error, p.u. 999

Dbd1Lower threshold for reactive powercontrol deadband (<=0)

<=0

Dbd1Upper threshold for reactive powercontrol deadband (>=0)

>=0

QmaxMaximum plant reactive powercommand, p.u.

0.00 to 0.43Set to 0. No voltage control allowed forcontinuous operation

QminMinimum plant reactive powercommand, p.u.

-0.43 to 0.00Set to 0. No voltage control allowed forcontinuous operation.

kpgReal power control proportionalgain, p.u.

- PPC specific

kigReal power control integral gain,p.u.

- PPC specific

tpActive power filter time constant,sec.

0.02 to 0.05 PPC specific

fdbd1Frequency deadband downside,p.u.

-0.01 to 0.00Set to - 0.0006 p.u. 0.036 hz deadband isrequired per attached SRD (0.036Hz/60Hz)

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Parameter DescriptionTypical Value

or range ofValues*

Comments

fdbd2 Frequency deadband upside, p.u. 0.00 to 0.01Set to 0.0006 p.u. 0.036 Hz deadband isrequired per attached SRD (0.036Hz/60Hz)

femaxMaximum power error in droopregulator, p.u.

-999

feminMinimum power error in droopregulator, p.u.

999

pmaxMaximum plant active powercommand, p.u.

N/ASet to greater of either PV or BESS MWrating, in p.u of 100 MVA base

pminMinimum plant active powercommand, p.u.

N/ASet to negative of BESS MW rating, in p.u of100 MVA base

tgPlant controller P output lag timeconstant, sec.

0.02 to 0.15 PPC specific

ddnReciprocal of down regulationdroop, p.u.

0.00 to 33.33Set to 20. 5% droop setting is required perattached SRD document.

dupReciprocal of up regulation droop,p.u.

0.00 to 33.33Set to 20. 5% droop setting is required perattached SRD document.

MVA_P Plant Controller MVA base N/ASet to 0. All p.u values in PLNTBU1 modelare to be provided on system (100 MVA)base.

*Typical values are provided only for guidance and should not be interpreted as a strict range of numbers.

Where N/A is listed, this indicates that there is no typical range to be provided.

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REAX4BU1 Model Guidelines – To be used in conjunction with PLNTBU1 for AC coupled PV+BESS

Note: one REAX4BU1 model is required for each PV or BESS unit that are AC coupled.

Model parameters are to be provided in per unit of machine MVA base.

Parameter DescriptionTypical Value

or range ofValues*

Comments

Tw1 (s), Measurement time constant N/A Inverter specific

Kw1 (pu onMBASE),

Gain for signal in reactive path -Irrelevant, since DERs not allowed to controlvoltage under normal operating conditions

Kp1(pu onMBASE),

Gain for signal in real path N/A

Wmax (pu), Maximum value of W01 - Irrelevant, since DERs not allowed to controlvoltage under normal operating conditionsWmin (pu), Minimum value of W01 -

Pmax (pu), Maximum value of P01 1 1 if either PV unit or BESS unit

Pmin (pu), Minimum value of P01 0 or -10 if PV unit-1 if BESS unit

*Typical values are provided only for guidance and should not be interpreted as a strict range of numbers.

Where N/A is listed, this indicates that there is no typical range to be provided.

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VTGTPAT and FRQTPAT Model Guidelines - Voltage and Frequency Trip Settings

The following parameters for voltage and frequency trip relay PSS/E models need to be used to

represent the required inverter trip settings specified in the attached SRD document.

Parameter Model Value Description

VL VTGTPAT 0.88Trip for voltages below 0.88pu for more than 3 seconds

VU VTGTPAT 999

TP VTGTPAT 3.0

VL VTGTPAT 0.5 Trip for voltages below 0.5pu for more than 1.1seconds

VU VTGTPAT 999

TP VTGTPAT 1.1

VL VTGTPAT 0Trip for voltages above 1.1pu for more than 2 seconds

VU VTGTPAT 1.1

TP VTGTPAT 2

VL VTGTPAT 0 Trip for voltages above 1.2pu for more than 0.16seconds

VU VTGTPAT 1.2

TP VTGTPAT 0.16

FL FRQTPAT 58.5 Trip for frequency below58.5 Hz for more than 300seconds

FU FRQTPAT 999

TP FRQTPAT 300

FL FRQTPAT 56.5 Trip for frequency below56.5 Hz for more than 0.16seconds

FU FRQTPAT 999

TP FRQTPAT 0.16

FL FRQTPAT 0 Trip for frequency above 62Hz for more than 0.16seconds

FU FRQTPAT 62

TP FRQTPAT 0.16

FL FRQTPAT 0 Trip for frequency above61.2 Hz for more than 300seconds

FU FRQTPAT 61.2

TP FRQTPAT 300

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REGC_B Block Diagram [Source: PSS/E]

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REEC_D Block Diagram [Source: PSS/E]

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REEC_D Block Diagram – Continued:

State Transition Diagram for dynamic voltage support during high or low voltage conditions

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REPC_A Block Diagram [Source: PSS/E]

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PLNTBU1 Block Diagram [Source: PSS/E]

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REAX4BU1 Block Diagram [Source: PSS/E]