Wind and Solar Modeling Update - NERC Modeling Powerflo… · · 2012-12-19Presentation Outline The need for wind and PV system planning models, WECC REMTF charter Wind plant models

Wind and Solar Modeling Update Western Electricity Coordinating Council Renewable Energy Modeling Task Force

October 3, 2012

Michael Behnke, [email protected] Abraham Ellis, [email protected]

Presentation Outline

The need for wind and PV system planning models, WECC REMTF charter

Wind plant models – Power flow representation – WECC wind turbine type designations – Current WECC-approved dynamic models – New models under development through REMTF PV plant models

– Power flow representation – New models under development through REMTF

2

Why Do We Need Models?

Interconnection Studies – Identify system impacts, test mitigation alternatives – Establish interconnection requirements Transmission Planning and Expansion Studies

– Test compliance against reliability criteria Evaluation of Future High Penetration Scenarios

– Guide evolution of standards and technology

3

Modeling and NERC Standards

Models are required for system reliability Inadequacy of models is major barrier to large-scale

integration of variable (solar & wind) generation

“Validated, generic, non-confidential, and public standard power flow and stability (positive-sequence) models for variable generation technologies are needed. Such models should be readily validated and publicly available to power utilities and all other industry stakeholders. Model parameters should be provided by variable generation manufacturers and a common model validation standard across all technologies should be adopted...”

Reference: NERC IVGTF Special Report, Accommodating High Levels of Variable Generation, http://www.nerc.com/files/IVGTF_Report_041609.pdf

4

What Type of Models?

• Power flow models – Facility loading (thermal), steady-state

voltage stability & voltage control • Dynamic models

– Large-signal transient stability • Short circuit models

– Breaker duty, protection design and coordination

• Detailed, full-order models – Electromagnetic phenomena – Control interaction

5

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WECC REMTF Charter

The Renewable Energy Modeling Task Force shall – Develop and validate generic, non-proprietary, positive-sequence

power flow and dynamic simulation models for solar and wind generation for use in bulk system studies

– Issue guidelines and model documentation – End goal: Models and model data are available in standard model

library of commercial simulation software REMTF activities support the Western Region’s initiatives

to maintain conformance with existing and emerging NERC MOD standards

REMTF activities supported by US DOE, coordinated by Sandia National Laboratories

Wind Models

WECC REMTF Wind and Solar Modeling Update, October 3, 2012

Power Flow Representation


Single-Machine Equivalent Model

POI or connection to the grid Collector System

Station

Feeders and Laterals (overhead and/or underground)

Individual WTGs

Interconnection Transmission Line

W

Pad-mounted Transformer Equivalent

Wind Turbine Generator Equivalent

PF Correction Shunt Capacitors

Collector System Equivalent

Interconnection Line

Plant-level Reactive Compensation

POI or Connection to Transmission System

Station Transformer(s)

W

W Type 4 WTG

Type 1 WTG

Interconnection Line

POI or Connection to Transmission System

Station Transformer(s)

Pad-mounted Transformer Equivalent

PF Correction Shunt Capacitors

Collector System Equivalent

Plant-level Reactive Compensation

…or in special cases (e.g., heterogeneous feeders or WTGs of different types)…

Equivalent Collector System


Equivalent impedance depends on WPP size, collector system topology, and line type (OH/UG)

If wind plant conductor schedule is available, Zeq and Beq, can be computed as follows

– For radial feeders with N WTGs and I branches:

ni = number of WTGs connected upstream of the i-th branch – Equations can be implemented easily on a spreadsheet Reproduces real/reactive losses assuming output from

WTGs is approximately uniform

21

2

N

nZjXRZ

I

iii

eqeqeq

∑==+= ∑

=

=I

iieq BB

1

Equivalent Collector System


Example with N=18 and I=21:

WECC Wind Plant Power Flow Model Guide


Procedure outlined in guideline available on WECC web site

http://www.wecc.biz/committees/Standing Committees/PCC/TSS/MVWG/Shared Documents/MVWG Approved Documents/WECC Wind Plant Power Flow Modeling Guide.pdf

http://www.wecc.biz/committees/StandingCommittees/PCC/TSS/MVWG/SharedDocuments/MVWGApprovedDocuments/WECCWindPlantPowerFlowModelingGuide.pdf�




WECC Wind Turbine Type Designations


Type 2 WTG Wound Rotor Induction Generator with variable rotor resistance

Type 1 WTG Cage Rotor Induction Generator

WECC Wind Turbine Type Designations


Type 3 WTG Doubly Fed Asynchronous Generator (DFAG)

Type 4 WTG Full Converter (FC)

Current Type 1 Generic Model Standard induction generator model, except that mechanical state variables are in

the wind turbine model Shunt caps represented separately in the power flow Has been validated against one manufacturer specific model (Mitsubishi 1000A)


Pseudo Governor

Model

Wind Turbine Model

GeneratorModel

MechanicalPower

Shaft Speed

Terminal Voltage

Real Power Pgen

QgenWT1GWT12T

WT1T

WT12AWT1P

Pseudo-Governor Model

Simplified representation of aero-torque/pitch control used in in Type 1 and Type 2 WECC generic models


Kdroop1

Σ

Σ1 + sTpe

KpKi

pimax

pimin

11 + sT1

11 + sT2

pgen

pmech

wref

pref

Σ Kwspeed

s+

Turbine-Generator Shaft Model Total inertia H (input) is assumed to be the sum of generator & turbine inertia (Hg +

Ht). Inertia fraction Htfrac and first shaft torsional resonant frequency, Freq1 are also user-specified

Stiffness constant K is internally calculated Shaft model is used in Type 1, Type 2 & Type 3 generic models


Tmech 1s

12Ht

K

Σ

1s

12Hg

ΣDshaft

Σ

+

+

+

+

Telec

-

-

-

ωο+

+ωgΣ-

ωο

+

+ω tΣ

1s

δ tg

Pmech

ω t

Pgen

ωg

∆ω t

∆ωg

∆ω tg ∆ω tg

..

..

Ht = H ∗ Htfrac

Hg = H - Ht

Ksh = H ω0.2Ht Hg (2π Freq1)2. . .

If Htfrac = 0, model defaults to single mass shaft

Current Type 2 Generic Model Same as Type 1 generic model, except that Rotor Resistance Model is added Has been validated against one manufacturer specific model (Vestas V80)


Wind Turbine Model

Rotor Resistance

Control Model

GeneratorModel

Shaft Speed

Terminal Voltage

Real Power Pgen

Qgen

Pseudo Governor

Model

Rotor Resistance

“Aero” Torque

Real Power

WT2GWT2E

WT12TWT2T

WT12AWT2P

Rotor Resistance Control Model

Calculates external rotor resistance to be inserted based on rotor speed and machine electrical power


Current Type 3 Generic Model Complex model in part because WTG topology allows for much wider range of

control options Has been validated against one manufacturer specific model (GE 1.5 MW)


WT3G

Converter ControlModel

Pitch Control Model

Wind Turbine Model

Blade Pitch

Generator /Converter

Model

Power Order

Speed Order

Shaft Speed

Current Command

Voltage Command

Real Power

Terminal Voltage

Regulated Bus Voltage

Real & Reactive Power

Pgen

QgenWT3E

WT3P WT3T

Generator/Converter Model Equivalent (algebraic) representation of generator & converter Flux dynamics neglected, mechanical states included in turbine model


Vterm

High VoltageReactive Current

Management

Low VoltageActive CurrentManagement

Isorc-1X"

IPcmd 11 + 0.02 s

11 + 0.02 s

s0

E q"cmd

jX "

LVPL & rrpwr

11 + 0.02s

LVPL

Low Voltage Power Logic

V

LVPL

brkptzerox

I Plv

V

Lvplsw = 1

Lvplsw = 0

Lvpl1

I Qlv

Electrical Control Model Includes several options for volt/var control, including plant-level


Vc

Pgen

Wind Plant Reactive Power Control Emulation

Kiv / s+

Vrfq

11 + sTc

11 + sTr

Qmax

Qmin

1/ fnKpv

1 + sTv

Qwv

11 + sTp

-1

Qref

0

varflg1

PFAreftan

x

+

+

++

Qgen

Vref

Vmax

Vterm

Kqv / s

XI Qmax

Vmin

Eq cmd

ToGenerator /Converter

Model

Kqi / s

Qord

Power FactorRegulator

Qcmd

Qcmd

Qmax

Qmin

XIQmin

vltflg

0

1

Σ Σ

ΣΣ

Volt/var Controller

Electrical Control Model Current limiting prevents total current magnitude from exceeding converter limits User-settable active/reactive injection priority


ImaxTDImaxTD

2 - IPcmd2

Minimum

IqmnIqmx

Ipmx

P, Q Priority Flag

-1

P Priority

10

Q Priority

Iqmn Iqmx

ImaxTD2 - IQcmd

2

I pmx

IQcmd

IPcmd

Minimum

Iphl

Minimum

-1

Minimum

I qhl Minimum

Vt

Iqmxv

Iqmxv1.6

qmax

1.0

Vt

WT3 Pitch Control Model

Calculates pitch angle as a function of speed and power error – Assumes pitch angle = 0 at rated and lower wind speed – Pset is normally set to 1.0


θ

ωref

Pord +

ωerrω

11 + sTPI

PI max

cmdθΣ+

+Pitch Control

Kpp + Kip / s

Anti- windup onPitch Limits

PitchCompensation

Kpc+ K ic / s

Anti- windup onPitch Limits

+

Σ

Σ

+

Pset

PI min

rate limit (PIrate )

WT3 Turbine Model


θ

BladePitch

PmechΣ

θο

+X Kaero Σ

Pmo

+

• Wind Turbine Aero Model Emulates computation of Pmech from

wind assuming that wind speed is constant (does not require power coefficients or CP curve)

Tmech 1s

12Ht

K

Σ

1s

12Hg

ΣDshaft

Σ

+

+

+

+

Telec

-

-

-

ωο+

+ωgΣ-

ωο

+

+ω tΣ

1s

δ tg

Pmech

ω t

Pgen

ωg

∆ω t

∆ωg

∆ω tg ∆ω tg

..

..

• Shaft model Same as Type 1 and

Type 2 generic models

Current Type 4 Generic Model Similar to the generic Type 3 model, except that pitch control module is not

included Has been validated against one manufacturer specific model (GE 2.5 MW)


Generator/Converter

Model

ConverterControlModel

IpCommand

PowerOrder

Vreg bus V term

IqCommand

Pgen , Qgen

WindTurbineModel

Pgen , Qgen

Pgen

WTG Dynamic Model Updates Underway

New WT1/WT2 pitch control model – Addresses unrealistic behavior of current model during frequency

deviations New WT3/WT4 models

– Reflect input from many more WTG and component manufacturers than current models

– Emphasis on representation of behavior during and shortly after disturbances (European Grid Codes)

– Modular approach to facilitate future model evolution and re-use for solar PV models


New WT1/WT2 Pitch Control Model


Existing

Re-designed (testing underway)

New WT1/WT2 Pitch Control Model Good results compared to two major Type 1 WTG vendor-specific PSCAD models


P-I block: Gain=1, Time Constant=0.1s Lag Filter: Gain=2, Time Constant=3 s Rate Limiter: Up(pitch back)=1.5, Dn(restore)=0.5

P-I block: Gain=1, Time Constant=0.001s Lag Filter: Gain=1, Time Constant=0.01 s Rate Limiter: Up(pitch back)=0.5, Dn(restore)=0.5

Source: Zavadil

New Renewable Energy Models Modular structure approach (also used for PV models)


Module Use REPC_A Wind/PV plant controller REEC_A Wind /PV inverter electrical controls REGC_A Generator/Converter model WTGT_A Simplified Drive Train WTGAR_A Aerodynamic Model WTGPT_A Pitch Control Model WTGTQ_A Torque Control Model lhvrt Voltage/Frequency Protection Model (any generator model)

WT3

PV1X

WT4

New Features Available for WT3 and WT4 Modeling

Controlled reactive current during and after LVRT event User-defined inverter time constants Options for different control implementations

– Dynamic reactive current limits – Voltage dip logic Separation of slower plant controls from faster converter

controls Additional functionality for active (droop) and reactive (droop,

line drop compensation) controls


New WT3/WT4 Model Testing


Initial validation – good news

Source: Pourbeik

ABB – WT3 Vestas – WT3

Solar Models

Copper Mountain 48 MW PV plant in Nevada (Picture: inhabitat.com)

http://inhabitat.com/�

PV Plant Power Flow Representation

How to equivalent collector system parameters? – Estimate based on typical design parameters – Calculate from as-built collector system design data – Adjust based on field data

Useful Reference: WECC Guide for Representation of Photovoltaic Systems in Large-Scale Load Flow Simulations

33

Dynamic Models for PV Plants

Level of detail consistent with application – Positive-sequence – Steady-state to 5 Hz (faster dynamics expressed

algebraically or ignored) – For PV, key dynamic modeling aspects are inverter current

limits, LV logic, and plant controls Current situation

– Vendor-specific models exist, mostly proprietary – Generic models under development – Ref: WECC REMTF, “Generic Solar Photovoltaic System Dynamic Simulation

Model Specification”, 2012

34

REMTF Dynamic Models for PV

In power flow, PV modeled explicitly as generator

Should include feeder or collector system equivalent per WECC guide

In dynamics, use stand-alone full-featured or simplified model

Simplified (PVD1 ) Full-Featured Model (PV1X) OR

÷

Vt

N

D×

Q Priority (Pqf lag =0)Iqmax = ImaxTDIqmin = - IqmaxIpmax = (ImaxTD2- Iqcmd2)1/ 2

P Priority (Pqf lag =1)Ipmax = ImaxTDIqmax = (ImaxTD2- Ipcmd2)1/ 2

Iqmin = - Iqmax

÷

0

Ipmax

Iqmin

Iqmax

0.01

N

D

×

Vt0 Vt1 Vt2 Vt3

1

0

V0 V1

DqdvQmx

QmnQref

Vrf lag

Freq

Ft0 Ft1 Ft2 Ft3

1

0

Frf lag

Ip

Iq

It = Ip +j Iq

-11 + sTg

11 + sTg

Ipcmd

Iqcmd

PVD1

XcIt

Qref

-Freq_ref Ddn

fdbdPdrp

Pref

Pext

Pdrp

Fvl

Ffh

Ff l

MINIMUM

Fvh

FvlFfhFf l Fvh

35

Q Control

P Control

Current Limit Logic

IqcmdIqcmd’

IpcmdIpcmd’

Generator Model

Network Solut ion

Plant Level V/ Q Control

Plant Level P Control

VrefVreg

QrefQbranch

PrefPbranchFreq_ref

Freg

Qext

Pref

REPC_A

Pqf lag

REEC_B REGC_AVt Vt

Iq

Ip

PV1X (Central System) Model Structure

Designed to be used with equivalent power flow model Very similar to REMTF generic WT4 WTG model Voltage and frequency protection limits represented separately

36

Q Control

P Control

Current Limit Logic

IqcmdIqcmd’

IpcmdIpcmd’

Generator Model

Network Solut ion

Plant Level V/ Q Control

Plant Level P Control

VrefVreg

QrefQbranch

PrefPbranchFreq_ref

Freg

Qext

Pref

REPC_A

Pqf lag

REEC_B REGC_AVt Vt

Iq

Ip

PV Plant Controller

37

REPC_A

1

0

Vreg

Vref

Freeze state if Vreg < Vfrz

Ibranch

Kc

-

Qbranchemax

emin

Kp + Ki s

pqmax

pqmin

1 + s Tf t1 + s Tfv QextRefFlag

dbd

11 + sTf lt r

VcompFlag|Vreg – (Rc+jXc)· Ibranch|

11 + sTf lt r

1

0

Qref

-

femin

femaxPbranch

Plant_pref

Ddn

Dup

0

0Freq_ref

- fdbd1,fdbd2

- Kpg + Kig s

Pmax

PminFreg

11 + sTp

11 + sTlag Pref

Closed loop voltage regulation with line drop comp. and voltage droop Closed loop reactive power regulation Governor response (droop) with separate up/down regulation

Inverter P/Q Electrical Controls

38

Local reactive control options (PF, Q control), voltage dip response Active power absolute and rate limit Converter current limit with P/Q priority

Current Limit LogicQ Priority (Pqf lag =0): Ipmax = (Imax2- Iqcmd2)1/ 2, Ipmin = 0 Iqmax = Imax, Iqmin = - IqmaxP Priority (Pqf lag =1): Ipmax = Imax, Ipmin = 0 Iqmax = (Imax2- Ipcmd2)1/ 2, Iqmin = - Iqmax

÷ Ipcmd11 + sTpord

Pmax & dPmax

Pmin & dPmin

Iqcmd

÷

Iqmax

Iqmin

Iqh1

Iql1

Kqvdbd1,dbd2

Vref0

Vt -

iqinj

REEC_B

pfaref

×

tan Qmin

Qmax11 + sTpPe 1

0

PfFlag

Qext Qgen

-Kqp + Kqi s

Vmax

Freeze state if Voltage_dip = 1Vmin

1

0Vmin

Vf lag VmaxIqmax

Kvp + Kvi s

Freeze state if Voltage_dip = 1Iqmin

11 + sTrv

Vt_f ilt

if (Vt < Vdip) or (Vt > Vup) Voltage_dip = 1else Voltage_dip = 0

Current Limit Logic

1

0

QFlag

-

Vt_f ilt 0.01

11 + sTiq Freeze state if

Voltage_dip = 1

Vt_f ilt0.01

Ipmax

Ipmin =0

Imax

Pqf lag

Freeze state if Voltage_dip = 1

Pref

Generator/Converter Model

High voltage Iq logic (software specific) Low voltage Ip management (approximate PLL response during voltage dips) Low voltage Ip logic to allow for controlled active current response during and

following voltage dips

39

REGC_A

Ipcmd 11 + sTg

LVPL & rrpwr

÷

lvpnt0 lvpnt1

gain

V

1

0×

Ipejπ/ 2

LOW VOLTAGE ACTIVE CURRENT

MANAGEMENT Vt

Iqcmd -11 + sTg

Iq×

Volim

-Khv

0

0

Vt ≤ Volim Vt > Volim

HIGH VOLTAGE REACTIVE CURRENT MANAGEMENT

Iolim

Vt

-

V

Zerox Brkpt

Lvpl1

LVPL

V

LOW VOLTAGE POWER LOGIC

0

1

Lvplsw1

1 + sTf lt r

Igen

Iqrmin

Iqrmax

Simple Dynamic Model (PVD1)

40

÷

Vt

N

D×

Q Priority (Pqf lag =0)Iqmax = ImaxIqmin = - IqmaxIpmax = (Imax2- Iqcmd2)1/ 2

P Priority (Pqf lag =1)Ipmax = ImaxIqmax = (Imax2- Ipcmd2)1/ 2

Iqmin = - Iqmax

÷

0

Ipmax

Iqmin

Iqmax

0.01

N

D

×

Vt0 Vt1 Vt2 Vt3

1

0

V0 V1

DqdvQmx

QmnQref

vrrecov

Freq

Ft0 Ft1 Ft2 Ft3

1

0

f rrecov

Ip

Iq

It = Ip +j Iq

-11 + sTg

11 + sTg

Ipcmd

Iqcmd

PVD1

XcIt

Qref

-Freq_ref Ddn

fdbdPdrp

Pref

Pext

Pdrp

Fvl

Ffh

Ff l

Fvh

Fvl

Ffh

Ff l

Fvh

×

Reactive power control with Q-V droop and line drop compensation Active power (high) frequency droop Voltage-frequency protection with deadband and recovery logic

Intended for use with a smaller PV plant or distribution-connected MW-scale plant

Distributed PV Power Flow Model

High penetration PV may warrant explicit power flow modeling

Challenge is to capture salient behavior without excessive model data requirements

41

Distributed PV Model Structure

WECC REMTF working on a model formulation based on WECC composite load model (CMPLDW)

42

In power flow, PV is netted with load, as described in previous slide In dynamics, load & PV are modeled behind an LTC + feeder model Different dynamic models are used for different load components & PV

Sanity Checks for Large Dynamics Cases Eric H. Allen

October 3, 2012

2

RELIABILITY | ACCOUNTABILITY

Basic Rules for Cases

• Study models for dynamics should be stable! We do not regularly observe growing oscillations on the

power system

System returns to quasi-equilibrium after a minor disturbance and stays there

• Study models for dynamics should initialize within limits! Violation of limits in a steady-state condition indicates that

powerflow data or dynamics data (or both) have errors

3


Machines with No Models

• Options: Generic models or load netting

• Preferable to use generic models (even for small units) Those small units add up!

Accuracy of oscillatory modes may be lost

Generic models can be added systematically in a single step

Improves network convergence by maintaining voltage sources throughout the network, reducing simulation time

CON conservation models (GENROA, GENSAA) can be used o Minimal additional data

o Marker to indicate generic vs. unit-specific data

4


Generic Models vs. Netting

Generic Netting Recorded

5


Initialization

• Process of starting a time-domain simulation

• Dynamics data matched to a powerflow condition

• Initial value of all state variables is calculated for the particular powerflow condition

• If any value falls outside limits prescribed by a model, a simulation should not be run Identify and fix the problem!!

6


Examples of Poor Initialization

• Machine field voltage = 82.2 p.u.

• Machine field voltage = -1.4 p.u.

• Machine terminal voltage = 1.50 p.u.

• Machine terminal voltage = 0.79 p.u.

7


Common Initialization Errors

• Exciter model limits incompatible with powerflow

• Governor model limits incompatible with powerflow

• Incorrect machine base value This critical dynamics parameter is carried with the

powerflow data in some programs

• Faulty generator data X’d > Xd , X’’d > X’d , Xl > X’’d are physically impossible!

Can be cause of exciter initialization errors

8



• MANY DYNAMICS INITIALIZATION PROBLEMS ARE A RESULT OF POWERFLOW DATA ERRORS Pmax, Pmin errors (or dispatch in ignorance of limits)

Qmax, Qmin errors

Machine base

Transformer impedance

Stator impedance (0.56 is not a credible value for resistance!)

• Limits in powerflow data should always be equally or more restrictive than limits in dynamics data Continuous operation implies a lower rating than a

temporary transient or overload condition

9



• MANY DYNAMICS INITIALIZATION PROBLEMS ARE A RESULT OF POWERFLOW DATA ERRORS

• Therefore, a powerflow case should not be deemed acceptable until it has been successfully initialized with dynamics data Otherwise, studies using the powerflow model may reach

inaccurate conclusions due to inaccurate limits

10


Standard Dynamics Case Tests

1. No-fault simulation As name says, simulation run with no fault (or any other

event)

System states should remain constant

2. Disturbance (ringdown) simulation(s) Application of a fault at a strategic location for a few cycles,

followed by removal of fault without any topological changes (i.e. no line switching)

System should return to essentially where it started

11


Evaluation of Tests

• Comparison of powerflow at end of simulation with the powerflow at beginning of simulation Generator MW

Generator MVAR

Line MW and MVAR

Voltage magnitude

• Plots of key voltages, angles, MW, MVAR

12


How Long to Simulate?

1. No-fault test – 20 s Based on experience, 20 s is the amount of time needed for

component model problems to appear (if they’re going to appear in this test)

2. Disturbance (ringdown) tests – 60 s 60 s is the amount of time needed for the system dynamics

to return to equilibrium and thus permit a suitable powerflow to be extracted from the simulation

13


No-fault Test

• Standard test for dynamics test

• Initial screening of case

• Necessary but not sufficient to demonstrate that the case is ready for use in studies

• Many egregious data errors have been observed that did not show up in no-fault simulations

14


Disturbance Tests

• Stronger test for stability of dynamics cases

• Rigor of these tests are comparable to contingency simulations Demonstrate robustness of case

• In 10+ years experience, every instance of failure of a 60 s disturbance test has resulted from data errors that require correction

15


Disturbance Test

16


Component Model Tests

• Exciter step response test Step change in voltage setpoint

• Governor step response test Step change in load

• Dynamics should settle at new equilibrium following a transient

17


Response should look like this …

EFD ETERM

18


Not this!

EFD ETERM

19


Or this!

EFD ETERM

20


Or this!

EFD ETERM

21


Or this!

EFD ETERM

22


and definitely not like this!

EFD ETERM

23


Governor: reasonable response:

SPD PMEC

24


Unreasonable response:

SPD PMEC

25


Unreasonable response:

SPD PMEC

26


Unreasonable responses:

•DATA NEEDS TO BE FIXED! Not ignored!

Not load netted!

System Modeling Problems

NERC Modeling Workshop – Bloomington, MN October 1-3, 2012

2 RELIABILITY | ACCOUNTABILITY

Per-unit System


Why Per Unit?

1. Simplifies computational efforts

2. Allows for common representation of all system data a. Makes comparison of system data easier (e.g., 230 kV vs.

500 kV, MVA vs. current, etc.)

b. Reduces errors resulting from unit disagreement (e.g., speed vs. frequency)

c. Streamlines combination of system models


Conversion to Per Unit

•


Adjusting Per Unit Quantities

•


Adjusting Per Unit Quantities

•


Bad Modeling


Initial Freq. Control Findings

• No system wide tuning strategy being employed

• Prior to interconnections of systems, it was necessary to tune each governor to regulate system frequency in isolation

• The necessity of stable isolated governing has given way in many cases to faster load ramping or AGC control


Hydro Step-Change Controls


Re-Tuned Hydro Controls


Unit 1

8 MVA

Unit 2

8 MVA

Unit 3

8 MVA

Unit 4

24 MVA

115 kV 4.16 kV

46 kV 2.4 kV

46 kV 2.4 kV

46 kV 2.4 kV

46 kV : 115 kV

NLT @ -1 Step

NLT @ +1 Step

±5% NLT @ Neutral Step

NLT @ +1 Step

Plant Voltage Mismatches

Circuit Breaker

1. Step-Up Transformers (GSUs) for the three 8 MVA Generators are not at the same tap settings

Typical Plant Switching Station Bus


Questions?

Modeling Workshop Wrap-up

NERC Modeling Workshop – Bloomington, MN October 1-3, 2012


Modeling Standards Update


MOD-010 through MOD-15

• System Analysis and Modeling Subcommittee (SAMS) has recommended a set of changes to these standards (with MVWG) based on: IVGTF report MVTF report SAMS modeling team standards review and

analysis

• Planning Committee has directed them to develop a Standards Authorization Request (SAR)


Proj. 2007-09 ― Gen. Verification

New Standards

• PRC-019 – Coordination of Generator Voltage Regulator Controls with Unit Capabilities and Protection

• PRC-024 – Generator Performance During Frequency and Voltage Excursions

• MOD-026 – Verification of Models and Data for Generator Excitation System Functions

• MOD-027 — Verification of Generator Unit Frequency Response



Standard to be Retired (Merged into MOD-025) • MOD-024 — Verification of Generator Gross

and Net Real Power Capability Standard to be Revised • MOD-025 — Verification of Generator Gross

and Net Reactive Power Capability Verification of Net Real Power Capability to be added



MOD-026-1 (draft 4)

PRC-024-1 (draft 4)

Successive Ballot and Non-Binding Poll

• 10/19/12 - 10/29/12

Formal Comment Period

• 09/28/12 - 10/29/12



MOD-025-2 (draft 3)

MOD-027-1 (draft 3)

PRC-019-1 (draft 3)


• 10/19/12 - 10/29/12


• 09/28/12 - 10/29/12




• 10/19/12 - 10/29/12


• MOD-026-1 and PRC-024-1

• 09/28/12 - 10/29/12


Workshop Wrap-up


Workshop Wrap-Up

• More high-speed data recorders needed inside power plants Independent of the plant controls Recording electrical and boiler/turbine

control parameters Disturbance measurement recorder is the

only device in a substation that has the potential for telling the truth.


Workshop Wrap-Up

• A chronological case creation process is needed Distributed or centralized Based on Breaker-Node detail MUST include case shakedown and

testing before release Who to do for Eastern Interconnection?


Workshop Wrap-Up

• Composite load models need to be promoted Analysis needed for Eastern & ERCOT

Interconnections’ load characteristics Engage NATF, national labs, and EPRI Potential DOE funding


Workshop Wrap-Up

The use of negligently maintained data, calculated in scrupulously structured programs, in carefully crafted studies, to produce plausible but totally misleading results Bad Modeling Bad Decisions


Now that you know what you know, what do you intend to do about it?

Sean Connery in the Untouchables


Questions?