ss-38 load modeling working group progress report npcc...this report documents the progress that the...

SS-38 Load Modeling Working Group Progress Report

Prepared by: SS-38 Load Modeling Working Group

Working Group Membership SS38 LMWG Progress Report Page i

Contributing SS-38 Load Modeling Working Group Members

Isen Widjaja, Chairman IESO

Dean Latulipe National Grid USA

Daniele D’Aquila New York ISO

Gene Ng Hydro One

Khin Swe NYPA

Hai (Quoc) Le NPCC

Simon Couture-Gagnon TransÉnergie

Chuanjiang (Chelsea) Zhu National Grid

Jence Mandizha NYSEG

Kannan Sreenivasachar ISO-New England

Jose Conto ERCOT

Jay Nair Nova Scotia Power

Corresponding Members

Eric Allen NERC

Shounak Abhyankar ISO-New England

Anish Joshi ISO-New England

Table of Contents SS38 LMWG Progress Report Page iii

Table of Contents

1. Introduction ............................................................................................................................ 1

2. Load Survey – End-Use Load Model .................................................................................... 2

2.1 Ontario........................................................................................................................................ 2

2.2 New England .............................................................................................................................. 5

2.3 New York .................................................................................................................................... 6

3. Rules of Association ............................................................................................................... 7

4. Populating the Composite Load Model ............................................................................... 11

4.1 Determining Load Breakdown ............................................................................................... 11

4.1.1 Ontario...................................................................................................................................... 11

4.1.2 New England ............................................................................................................................ 12

4.1.3 New York .................................................................................................................................. 13

4.2 Parameters for Three-Phase Motors ..................................................................................... 13

4.3 Parameters for Single-Phase A/C Motors ............................................................................. 14

4.4 Parameters for Electronic Loads ........................................................................................... 14

4.5 Parameters for Static Loads ................................................................................................... 14

4.6 Motor Load Protection Settings ............................................................................................. 15

5. Benchmarking Tests ............................................................................................................ 17

5.1 Motor Load Protection Settings ............................................................................................. 17

5.2 System Events .......................................................................................................................... 17

5.3 Ontario...................................................................................................................................... 18

5.4 New York .................................................................................................................................. 22

6. Preliminary Composite Load Model.................................................................................... 24

6.1 Ontario...................................................................................................................................... 24

6.2 New England ............................................................................................................................ 26

6.3 New York .................................................................................................................................. 28

7. Installation of Data Recorders ............................................................................................ 31

8. Next Steps ............................................................................................................................. 32

9. References ............................................................................................................................ 33

SS38 LMWG Progress Report Page iv

List of Figures

Figure 1: End-use breakdown for Ontario’s Residential sector in 2013. ...................................................... 3

Figure 2: End-use breakdown for Ontario’s Commercial sector in 2013. .................................................... 4

Figure 3: End-use breakdown for Ontario’s Industrial sector in 2013. ......................................................... 4

Figure 4: A 500 kV bus voltage for July 5, 2010 benchmarking tests. ....................................................... 20

Figure 5: A 230 kV bus voltage for November 26, 2010 benchmarking tests. ........................................... 20

Figure 6: A 500 kV bus voltage for November 30, 2010 benchmarking tests. ........................................... 21

Figure 7: A 500 kV bus voltage for March 16, 2015 benchmarking tests. ................................................. 21

Figure 8: Voltage Response for a 3 Phase fault on a 345 kV line in New York. ........................................ 23

Figure 9: Basecase – Voltage Response for 3 Phase fault on a 345 kV line in New York. ........................ 29

Figure 10: CE Margin Case - Voltage Response for 3 Phase fault on a 345 kV line in New York. ........... 30

Table of Contents SS38 LMWG Progress Report Page v

List of Tables

Table 1: Ontario end-use load categories. ..................................................................................................................... 3

Table 2: New England end-use load breakdown. .......................................................................................................... 5

Table 3: Load Component Rules of Association developed for New England. [2] ....................................................... 8

Table 4: Motor load breakdown for the CMLD Composite Load Model for Ontario in 2012. ................................... 11

Table 5: Motor load breakdown for the CMLD Composite Load Model for New England. ....................................... 12

Table 6: Motor load breakdown for the CMLD Composite Load Model for New York. ............................................ 13

Table 7: Composite load model parameters from tests performed by WECC. [3] ...................................................... 14

Table 8: Single-phase A/C load model parameters from tests performed by WECC. [4] ........................................... 14

Table 9: 3-phase motor load protection settings (For Motors A, B and C). Tables III and VI in [6] .......................... 15

Table 10: 3-phase industrial motor load protection settings (For Industrial motors A, B and C). Table VII in [6] ..... 15

Table 11: Single-phase A/C motor load protection settings (For motor D). [4] .......................................................... 15

Table 12: Protection settings tested for Ontario benchmarking tests. .......................................................................... 18

Table 13: Simulated vs. Observed load loss for Ontario events. ................................................................................. 19

Chapter 1 Introduction

SS38 LMWG Progress Report Page 1

1. Introduction

In 2013, the NPCC SS-38 Working Group on Inter-Area Dynamics completed a Load Modeling

White Paper, which addressed the final recommendation developed by the Blackout

Recommendation Study Working Group.

This white paper provided information on the past and present NPCC load modeling practices as

well as those of other NERC regions. The working group also investigated the performance of

various dynamic load models and how the responses compare to those obtained with the standard

models which have traditionally been used.

The major conclusions and recommendations from the white paper are as follows.

Conclusions

1. The load modeling practices utilized in the NPCC region for transient simulations has

remained largely the same for the past 30+ years.

2. A few other NERC regions are currently either: i) investigating how they can improve

their load model for dynamic studies; or ii) have already implemented a dynamic load

model for some dynamic studies.

3. Transient stability simulation results can differ significantly whether a dynamic load

model or a static load model is utilized.

4. For some event re-construction simulations, the modeling of dynamic motor loads lead to

more accurate post-fault voltage responses compared to those obtained using the standard

static load model.

5. The WECC composite load model provides the most flexibility of the dynamic load

models tested, however, it is the most complex to set up and apply.

6. Modeling the frequency dependency of load does not significantly impact the results

obtained compared to those using the static load model.

Recommendations

1. Initiate a load survey to improve the accuracy of dynamic load model data.

2. Investigate the use of load monitoring equipment to aid in the benchmarking of dynamic

load models used in transient stability studies.

3. Continue investigating the use of dynamic load models for transient stability studies.

As these recommendations were expected to require a lot of time and effort to address, a Load

Modeling Working Group (LMWG) was formed by the NPCC in 2013.

This report documents the progress that the SS-38 LMWG has made to fulfill these

recommendations, with a large focus on the first task of improving the accuracy of the data

which is used by the dynamic load models. This report also provides a very preliminary

composite load model for each area in NPCC based on the data compiled that the user can use

for transient simulations to show compliance with NERC’s upcoming Transmission Planning

Standard TPL-001-4.


Chapter 2 Load Survey – End-Use Load Model

2. Load Survey – End-Use Load Model

From the results of the simulations performed for the SS-38 Load Modeling White Paper, it was

observed that varying the amount of motor load modeled in the system can have a significant

impact on the results obtained. Therefore, obtaining an accurate load distribution to populate

these dynamic load models is very important.

Knowing how load is consumed on an end-use level can provide valuable insight as to how much

load should be modeled as motor load. Obtaining an end-use load breakdown can be done by

performing a load survey. As the amount of motor load in the system can depend on a variety of

factors such as time and weather, these surveys should capture end-use load consumption for

summer peak, winter peak and light load conditions.

The load surveys performed varied between each area in NPCC. The New England load survey

was performed by a third party consultant; while data for Ontario’s end-use load model was

developed by the Independent Electricity System Operator (IESO) as part of Ontario’s 2013

Long-Term Energy Plan project.

2.1 Ontario

As part of the 2013 Long-Term Energy Plan, the IESO produced a demand forecast for Ontario

on an end-use level. The demand forecast accounts for the following five demand sectors, with

the first three making up the majority of Ontario’s load:

1. Residential – Includes single family homes, medium and high rise buildings

2. Commercial – Includes office buildings, non-food retail, schools, and

universities/colleges

3. Industrial – Includes mining, primary metals, paper and chemical manufacturing

4. Agricultural

5. Electrification of Transport

The residential, commercial and industrial sectors are further separated into the end-use load

categories listed in

Table 1 for each of the ten zones in Ontario:

Northwest

Northeast

Essa

East

Ottawa

Toronto

Niagara

Southwest

Bruce

West



Table 1: Ontario end-use load categories.

Residential Commercial Industrial

Air Conditioning Miscellaneous Cooling Compressed Air

Central Heating On-Site Generation Heating Electro-Chemical

Clothes Dryers Other Consumer Electronics Lighting HVAC

Clothes Washers Refrigerators Computer Equipment Lighting

Computers Set Top Boxes Cooking Motors Fans Blowers

Cooking Space Heating Room Domestic Hot Water Motors Other

Dehumidifiers Swimming Pool Pumps Elevators Motors Pumps

Dishwashers Televisions HVAC Fans Pumps Other

Domestic Hot Water Ventilation And Circulation Miscellaneous Equipment Process Cooling

Elevators

Other Process Heating

Freezers Other Plug Loads Process Specific

Lighting Refrigeration

To develop a load forecast at an end-use load level, the IESO used the following methodology:

1. Obtain energy data by sector and end use from existing data.

2. Use demographic and economic drivers as well as energy prices to help forecast the

change in demand over time.

3. Calibrate the model with other external data sources on a zonal and system wide basis.

4. Apply end-use level hourly load shapes to the annual energy demand to obtain gross

hourly demand values for each of the 10 Ontario zones.

Breakdowns for the residential, commercial and industrial sectors for all of Ontario in 2013 for

summer peak load can be seen in Figures 1 – 3. For additional information, please refer to

Module 1: Demand Forecast located at IESO 2013 Long-Term Energy Plan website [1].

Figure 1: End-use breakdown for Ontario’s Residential sector in 2013.



Figure 2: End-use breakdown for Ontario’s Commercial sector in 2013.

Figure 3: End-use breakdown for Ontario’s Industrial sector in 2013.



2.2 New England

An end-use load survey was conducted for New England in 2014 [2]. From this survey, the

breakdowns for the peak load and light load hours are provided in Table 2:

Table 2: New England end-use load breakdown.

Percent of Peak Load Percent of Light Load

Agriculture 0.07% 0.09%

Air Compression 0.41% 0.45%

All Other Electronics 2.88% 2.23%

All Other End Uses - COM 4.97% 6.63%

All Other End Uses - RES 3.82% 7.19%

Ceiling Fans 0.51% 0.04%

Clothes Dryers 1.41% 2.60%

Clothes Washers 0.30% 0.55%

Construction 0.00% 0.00%

Conventional Boiler Use 0.10% 0.16%

Cooking 0.42% 0.68%

CRT TVs 0.35% 0.66%

Dishwashers 0.12% 0.42%

Electro-Chemical Processes 0.65% 1.22%

Elevator drives and hydraulic pumps 0.23% 0.45%

Lighting - CFL/Linear Fluorescent 11.69% 12.05%

Lighting - HID Interior 1.60% 2.02%

Lighting - Incandescent 2.50% 4.39%

Lighting - Other 1.63% 2.56%

Machine Drive 4.56% 7.57%

Mining 0.05% 0.08%

Office Equipment 3.46% 4.05%

Onsite Transportation 0.02% 0.03%

Other Facility Support 0.25% 0.40%

Other Nonprocess Use 0.04% 0.06%

Other Process Use 0.31% 0.53%

Other TVs (LED, LCD, Plasma, etc.) 0.46% 0.62%

Pool Pumps 2.90% 0.00%

Process Cooling and Refrigeration 0.82% 1.22%

Process Heating 1.19% 2.01%

Range/Oven 0.22% 1.04%

Refrigeration 4.53% 7.30%

Refrigerators/Freezers 3.70% 5.66%

Settop/cable box, digital, DVR 1.36% 2.41%

Space Cooling - Single Phase 8.78% 0.89%

Space Cooling - Split Phase 14.47% 1.04%

Space Cooling - Three Phase 11.25% 4.36%

Space Heating 0.01% 2.62%

Ventilation 5.55% 6.65%

Water Heating 2.18% 6.18%

Well Pumps 0.26% 0.90%



2.3 New York

The New York Control Area (NYCA) system load representation for summer peak and light load

are shown in Table 6 in Section 4.1.3, this table lists the percentage of motor and electronic loads

by zone. The percentages were derived based upon New York (NY) utility data at the retail level

as reported to the U.S. Energy Information Administration (EIA), together with NYISO data

from 2013 obtained from the Load Forecasting group which was used to adjust retail usage to

BPS usage (Commercial, Residential & Industrial). To determine the percentage of motor loads

in each zone, the ‘End-Use Data Development for Power System Load Model in New England’

study completed in April 2014 by DNV GL Energy [2] was used as a reference as New England

is similar to New York in weather and load patterns. The breakdown of the end-use shares of

loads is explained under Section 3, ‘Rules of Association’, of this report. In the NYISO analysis,

the Con Edison (Zone I & J) end-use shares of loads are modeled as similar to Massachusetts

East and LIPA/ PSEG (Zone K) as Connecticut. All other New York zone end-use shares of

loads are modeled similar to Massachusetts West/Central.

Chapter 3 Rules of Association


3. Rules of Association Although it is possible to split a load into each of the end-use load categories listed above, this

approach would be too impractical to apply system wide for simulation purposes. Therefore the

end-use load data obtained through the load surveys must be aggregated to fit the dynamic load

models that the LMWG plan to test.

Out of all of the load characteristic models available in PSSE, the CMLD composite load model

developed for the Western Electricity Coordinating Council (WECC) Load Modeling Task Force

(LMTF) is the most complex, with the ability to model various 3-phase motors as well as single-

phase A/C motors at any given load bus in the case. This model was developed by the WECC

LMTF when observed system responses for events in 1996 could not be reproduced using the

standard static load models at the time. These events demonstrated a phenomenon known as

Fault-Induced Delayed Voltage Recovery (FIDVR), where system voltages remain depressed for

several seconds following the clearing of a transmission system fault. The categories for this

composite load model include the following:

Three-phase motors

o Motor A: Motors driving constant torque loads (e.g. commercial/industrial A/C,

compressors, refrigerators)

o Motor B: Motors driving torque speed-squared loads with high inertia (e.g. fans)

o Motor C: Motors driving torque speed-squared loads with low inertia (e.g.

pumps)

Single-phase air-conditioner motor loads

Electronic loads

Static loads

As part of the New England end-use load model effort, some rules of association were developed

by DNV GL to help map each end-use load category into each category of the CMLD composite

load model as listed above. To develop the rules of association for New England, DNV GL used

the rules that the WECC had developed for their system as a starting point, and made any

modifications, where applicable, using engineering judgment and any available data sources [2].

These rules of association can be found in Table 3.



Table 3: Load Component Rules of Association developed for New England. [2]

Sector End Use Sector Class Electronics Motor-A Motor-B Motor-C Motor-D Constant Current

Constant Impedance

Residential

All Other Electronics Multi-family 0.9

0.1

Single-family/ Mobile Home 1

All Other End Uses - RES Multi-family 0.3

0.1 0.1

0.5

Single-family/ Mobile Home 0.3

0.1 0.1

0.5

Ceiling Fans Multi-family

1

Single-family/ Mobile Home

1

Clothes Dryers Multi-family

0.2

0.8


0.2

0.8

Clothes Washers Multi-family

0.85

0.15


0.85

0.15

CRT TVs Multi-family 1


Dishwashers Multi-family

0.3

0.7


0.3

0.7

Lighting - CFL/Linear Fluorescent Multi-family

1


1

Lighting - Incandescent Multi-family

1


1

Lighting - Other Multi-family

1


1

Other TVs Multi-family 1


Pool Pumps Multi-family

1


1

Range/Oven Multi-family

0.1

0.9


0.1

0.9

Refrigerators/Freezers Multi-family

0.1

0.9


0.1

0.9

Set-top/cable box, digital, DVR Multi-family 0.9

0.1

Single-family/ Mobile Home 0.9

0.1

Space Cooling - Single Phase Multi-family

0.1

0.9


0.1

0.9

Space Cooling - Split Phase Multi-family

0.3

0.7


0.3

0.7

Space Cooling - Three Phase Multi-family 0.15 0.5 0.25 0.1

Single-family/ Mobile Home 0.15 0.5 0.25 0.1

Space Heating Multi-family

0.05

0.15

0.8




Constant Impedance


0.3

0.7

Water Heating Multi-family

1


1

Well Pumps Multi-family

1


1

Commercial

Air Compression All commercial classes

1

All Other End Uses - COM Healthcare 0.2

0.8

All other commercial classes 0.2

0.4 0.4

Cooking All commercial classes 0.1

0.05

0.85

Elevator drives and hydraulic pumps All commercial classes

1

Lighting - CFL/Linear Fluorescent All commercial classes

1

Lighting - HID Interior All commercial classes

1

Lighting - Incandescent All commercial classes

1

Lighting - Other All commercial classes

Office Equipment All commercial classes 1

Refrigeration

Lodging 0.1 0.4

0.5

Healthcare 0.2 0.7

0.1

All other commercial classes 0.1 0.8

0.1

Space Cooling - Single Phase All commercial classes

1

Space Cooling - Split Phase All commercial classes

1

Space Cooling - Three Phase All commercial classes 0.15 0.85

Space Heating

Healthcare

0.75

0.15

0.1

All other commercial classes

0.7

0.2

0.1

Ventilation All commercial classes 0.3

0.7

Water Heating All commercial classes

1

Industrial

Agriculture All industrial Classes 0.1 0.2 0.25 0.35

0.1

Construction All industrial Classes 0.15

0.4 0.15 0.15

0.15

Conventional Boiler Use All industrial Classes

1

Electro-Chemical Processes All industrial Classes 0.15 0.15 0.25 0.15 0.15

0.15

Lighting - CFL/Linear Fluorescent All industrial Classes

1

Lighting - HID Interior All industrial Classes

1

Machine Drive All industrial Classes 0.3 0.42

0.28

Mining All industrial Classes 0.05 0.2 0.35 0.35

0.05

Onsite Transportation All industrial Classes 1

Other Facility Support All industrial Classes 0.5

0.25 0.25

Other Nonprocess Use All industrial Classes 0.5

0.25 0.25

Other Process Use All industrial Classes 0.1 0.15 0.25 0.25 0.25

Process Cooling and Refrigeration All industrial Classes 0.1 0.55 0.15 0.15 0.05




Constant Impedance

Process Heating All industrial Classes

0.05 0.05 0.05 0.05

0.8

Space Cooling - Three Phase All industrial Classes 0.1 0.9

Ventilation All industrial Classes 0.3

0.7

Chapter 4 Populating the Composite Load Model


4. Populating the Composite Load Model Once the end-use load model and rules of association have been established, the LMWG can

begin populating the composite load models. As the CMLD composite load model in PTI is

currently the most complex load model available, the LMWG focused on populating this model.

As the WECC LMTF has extensive experience with this load model, the LMWG relied on

reports that the WECC LMTF released regarding the parameters used for these models. These

primarily include [3] and [4].

The CMLD composite load model in PTI has upwards of 130 parameters. The motor themselves

take up 95 of these parameters, with each 3-phase motor taking up 20 parameters, and the A/C

motor requiring 35. As previously mentioned, the CMLD composite load model has the ability to

model:

Three different three-phase motor loads

Single-phase motor loads

Electronic loads

Static loads

4.1 Determining Load Breakdown

By applying the rules of association to the end-use load model, each area can determine the

breakdown of the various load models listed above. This will account for 5 parameters in the

CMLD model (i.e. fractions of motor and electronic load). The remaining load is modeled as

static load where the standard model for each area is used.

4.1.1 Ontario

The base year data that was provided by the IESO for Ontario’s end-use load model is 2012.

Table 4 lists Ontario’s motor load breakdown for the CMLD composite load model in PTI in

2012 for Summer Peak, Winter Peak, and Light Load conditions after applying the rules of

association to the end-use load model provided by the IESO. The values for the remaining

parameters in the CMLD load model are the same as the values specified in Section 4.

Industrial loads in Ontario were identified and rezoned so that the motor load breakdown for

industrial loads could be applied there.

Table 4: Motor load breakdown for the CMLD Composite Load Model for Ontario in 2012.

Load

Condition Zone

Motor Load Breakdown w/o Industrial Load Industrial Load Breakdown

Motor A Motor B Motor C Motor D Electronic Motor A Motor B Motor C Motor D Electronic

Peak

Load

Bruce 9.0% 3.83% 9.23% 3.8% 1.9% 29.7% 30.0% 16.6% 0.0% 0.0%

East 21.2% 4.45% 13.77% 20.5% 8.4% 28.5% 28.6% 18.1% 0.0% 0.0%

Essa 17.9% 4.03% 11.52% 24.8% 9.5% 30.1% 32.1% 16.1% 0.0% 0.0%

Niagara 21.1% 3.51% 12.83% 22.5% 8.0% 26.7% 27.1% 18.3% 0.0% 0.0%

Northeast 17.8% 4.60% 13.61% 13.3% 10.5% 30.3% 30.8% 13.5% 0.0% 0.0%

Northwest 17.2% 5.34% 16.45% 12.0% 9.5% 27.5% 37.3% 20.4% 0.0% 0.0%

Ottawa 19.9% 3.39% 11.53% 23.2% 9.7% 24.6% 26.3% 15.9% 0.0% 0.0%

Southwest 20.5% 3.66% 11.91% 21.6% 8.8% 26.7% 27.0% 15.5% 0.0% 0.0%

Toronto 22.2% 2.64% 11.36% 21.6% 8.9% 30.1% 30.1% 17.8% 0.0% 0.0%

West 21.5% 4.75% 13.86% 20.5% 8.1% 32.6% 33.2% 17.7% 0.0% 0.0%

Light

Load

Bruce 6.1% 6.48% 15.62% 1.7% 3.2% 27.1% 30.0% 16.7% 0.0% 0.0%

East 5.2% 8.74% 21.99% 7.9% 12.1% 26.3% 29.3% 18.6% 0.0% 0.0%



Essa 3.4% 9.26% 18.02% 10.1% 14.1% 28.1% 32.6% 16.1% 0.0% 0.0%

Niagara 2.9% 4.73% 14.27% 4.9% 7.7% 24.4% 27.9% 19.3% 0.0% 0.0%

Northeast 2.4% 8.24% 15.20% 9.6% 11.9% 29.9% 30.3% 14.7% 0.0% 0.0%

Northwest 3.8% 8.77% 19.92% 8.9% 11.1% 27.3% 36.5% 22.7% 0.0% 0.0%

Ottawa 3.6% 8.05% 20.37% 8.7% 15.4% 23.1% 25.4% 15.4% 0.0% 0.0%

Southwest 3.8% 7.94% 19.38% 8.3% 12.8% 24.7% 26.1% 15.3% 0.0% 0.0%

Toronto 3.6% 6.28% 21.16% 7.3% 14.1% 28.2% 30.7% 18.3% 0.0% 0.0%

West 5.6% 9.17% 21.64% 7.9% 11.6% 32.0% 33.5% 17.6% 0.0% 0.0%

Winter

Peak

Load

Bruce 5.7% 5.31% 16.51% 0.8% 1.5% 28.4% 30.4% 16.7% 0.0% 0.0%

East 4.1% 4.11% 22.77% 3.1% 5.5% 27.7% 29.0% 18.1% 0.0% 0.0%

Essa 3.0% 3.53% 19.33% 3.7% 6.5% 29.2% 32.7% 16.2% 0.0% 0.0%

Niagara 4.4% 3.57% 25.12% 3.2% 5.8% 25.8% 27.1% 18.0% 0.0% 0.0%

Northeast 2.0% 3.02% 17.07% 3.6% 5.4% 30.7% 30.3% 12.6% 0.0% 0.0%

Northwest 3.2% 3.55% 19.29% 3.2% 4.7% 28.1% 36.7% 19.3% 0.0% 0.0%

Ottawa 3.6% 2.97% 20.78% 3.1% 5.7% 24.2% 26.3% 15.7% 0.0% 0.0%

Southwest 3.3% 2.88% 20.19% 3.2% 5.8% 26.1% 27.1% 15.5% 0.0% 0.0%

Toronto 4.0% 2.70% 25.08% 3.2% 5.8% 29.6% 30.5% 17.7% 0.0% 0.0%

West 4.7% 4.37% 22.10% 3.1% 5.5% 32.6% 33.4% 17.6% 0.0% 0.0%

Ontario’s standard static load model is used for the static portion of the composite load model.

Section 2.4 of the Ontario Resource and Transmission Assessment Criteria document specifies

that if specific information is not available, the following voltage dependent load model should

be used:

P=P0V1.5

and Q=Q0V2.0

4.1.2 New England

For the peak and light load conditions, the CMLD composite load model breakdown for New

England is provided in Table 5.

Table 5: Motor load breakdown for the CMLD Composite Load Model for New England.

Load

Condition New England Region Electronic Motor A Motor B Motor C Motor D

Constant

Current

Constant

Impedance

Summer Peak

Load

Connecticut 18% 14% 12% 6% 25% 12% 13%

Massachusetts - East 16% 18% 12% 7% 23% 12% 13%

Massachusetts - West/Central 14% 15% 13% 8% 25% 10% 14%

Maine 16% 15% 12% 9% 19% 12% 17%

New Hampshire 16% 16% 12% 8% 18% 13% 17%

Rhode Island 14% 15% 13% 7% 26% 11% 14%

Vermont 15% 17% 11% 10% 19% 12% 16%

New England Overall 16% 16% 12% 7% 23% 12% 14%

Light Load

Connecticut 20% 15% 10% 7% 9% 11% 28%

Massachusetts - East 20% 15% 10% 7% 9% 13% 26%

Massachusetts - West/Central 20% 16% 10% 8% 9% 11% 27%

Maine 19% 14% 9% 9% 8% 11% 30%

New Hampshire 19% 14% 10% 8% 8% 12% 30%

Rhode Island 19% 15% 10% 7% 9% 12% 28%

Vermont 18% 15% 10% 8% 8% 12% 29%

New England Overall 19% 15% 10% 8% 9% 12% 27%



4.1.3 New York

Table 6 shows the percentages for the different induction motor and electronic loads in each

NY zone. They were derived from a combination of end-use load shares and BPS usage

(Commercial, Residential & Industrial) as explained in Section 2.3. These parameters are

used in the Siemens PTI dynamic composite load model (CMLD). The remaining load in the

zone after applying these specified percentages is modeled as static load.

Table 6: Motor load breakdown for the CMLD Composite Load Model for New York.

Load Condition Zone Motor Load Breakdown w/o Industrial Load

Motor A Motor B Motor C Motor D Electronic

Summer Peak Load

A 17.9% 12.6% 9.9% 21.2% 15.5%

B 17.8% 13.0% 7.6% 20.2% 15.3%

C 16.5% 12.9% 10.1% 23.4% 15.0%

D 16.1% 12.9% 10.1% 24.0% 14.9%

E 17.9% 12.6% 9.9% 21.3% 15.5%

F 19.4% 12.4% 9.8% 18.9% 15.9%

G 18.0% 12.9% 8.2% 20.4% 15.4%

H 16.4% 12.8% 8.7% 24.5% 15.1%

I 19.9% 12.1% 6.7% 19.9% 16.3%

J 19.9% 12.1% 6.7% 19.9% 16.3%

K 17.6% 11.7% 6.6% 20.7% 17.7%

Light Load

A 15.8% 9.7% 9.0% 11.7% 20.1%

B 12.2% 9.9% 7.2% 13.8% 20.2%

C 14.2% 9.7% 8.4% 12.6% 20.2%

D 16.2% 9.7% 9.2% 11.4% 20.1%

E 15.1% 9.7% 8.7% 12.1% 20.1%

F 16.5% 9.7% 9.3% 11.3% 20.1%

G 14.1% 10.5% 7.1% 12.0% 19.9%

H 13.2% 10.5% 6.5% 12.7% 20.0%

I 14.9% 11.6% 5.5% 10.8% 19.7%

J 14.9% 11.6% 5.5% 10.8% 19.7%

K 15.6% 11.3% 6.1% 10.9% 19.4%

NYPA and National Grid provided the buses that were strictly industrial load. These loads

were broken down similar to Massachusetts West/Central area industrial loads from the

cross-sector end-use shares table developed by DNV GL Energy for New England.

4.2 Parameters for Three-Phase Motors

As the data after applying the rules of association to the end-use load model only accounts for 5

parameters in the CMLD model (i.e. fractions of motor and electronic load), the LMWG had to

use various sources to help populate the remaining parameters. For this, the LMWG turned to the

extensive testing and experiments that the WECC LMTF had performed to determine parameters

for their load model. As outlined in [3], WECC utilities have tested a number of end-use loads to

aid in their model development. The resulting model parameters from these tests for residential

and commercial motors (MA-MC), as well as industrial motors (IA-IC) can be found in Table 7.



Table 7: Composite load model parameters from tests performed by WECC. [3]

Parameter MA MB MC IA IB IC

LF - Loading factor 0.75 0.75 0.75 0.85 0.85 0.85

Pf - Power Factor 0.78 0.78 0.78 0.89 0.89 0.89

Ls - Synchronous reactance 1.8 1.8 1.8 3.1 3.1 3.1

Lps - Transient reactance 0.12 0.19 0.19 0.2 0.2 0.2

Lpps - Sub-transient reactance 0.104 0.14 0.14 0.165 0.165 0.165

Ra - Stator resistance 0.04 0.03 0.03 0.01 0.01 0.01

Tpo - Transient open circuit time constant 0.095 0.2 0.2 0.8 0.8 0.8

Tppo - Sub-transient open circuit time constant 0.0021 0.0026 0.0026 0.0026 0.0026 0.0026

H - Inertia constant 0.05 0.5 0.15 0.15 1 0.2

Etrq - Torque speed exponent 0 2 2 0 2 2

4.3 Parameters for Single-Phase A/C Motors

The model data for single-phase residential air-conditioning load was also obtained through

laboratory tests. These tests were performed by Bonneville Power Administration (BPA),

Electric Power Research Institute (EPRI) and Southern California Edison (SCE) on more than 25

residential air-conditioners. Based off of these tests, an air-conditioner load model was

developed to replicate the actual performance observed during under-voltage transients, voltage

oscillations and frequency oscillations. Details on the tests and how they compare to actual

observed data can be found in [4]. The model parameters from the tests performed are found in

Table 8.

Table 8: Single-phase A/C load model parameters from tests performed by WECC. [4] Parameter Value Parameter Value

Tstall - stall delay (sec) 0.033 Np1 - real power exponent for running state 1 1

Trestart - restart delay (sec) 0.4 Kq1 - reactive power constant for running state 1 6

Tv - voltage input time constant (sec) 0.02 Nq1 - reactive power exponent for running state 1 2

Tf - frequency input time constant(sec) 0.05 Kp2 - real power constant for running state 2 12

CompLF - compressor load factor (p.u.) 1 Np2 - real power exponent for running state 2 3.2

CompPF - compressor power factor 0.97 Kq2 - reactive power constant for running state 2 11

Vstall - compressor stall voltage at base condition (p.u.) 0.7 Nq2 - reactive power exponent for running state 2 2.5

Rstall - compressor motor resistance (p.u.) 0.124 Vbrk - compressor motor "breakdown" voltage (p.u.) 0.86

Xstall - compressor motor stall reactance (p.u.) 0.114 CmpKpf - real power constant for freq dependency 1

LFadj - Load factor adjustment to the stall voltage 0.3 CmpKqf - reactive power constnt for freq dependency -3.3

Kp1 - real power constant for running state 1 0

4.4 Parameters for Electronic Loads

WECC had tested various electronic loads such as PCs, TVs and Variable Frequency Drives [3]

and found that they behave as a constant power load and operate at unity power factor. WECC

found that electronic loads will trip for low voltage conditions typically in the range of 0.55 –

0.7 p.u.

4.5 Parameters for Static Loads

A static load model was used to model the remaining non-motor and non-electronic load. These

include resistive loads such as incandescent lighting, resistive heating and resistive cooking. The

parameters for this model will vary between each area in NPCC and are based on each area’s

past load modeling practices.



4.6 Motor Load Protection Settings

A major component of the CMLD composite load model is the protection settings for the motor

loads. The model contains numerous protection settings for both single- and three-phase motors,

which include the under-voltage relay trip and reclose settings for three-phase motors, and under-

voltage contactor dropout and reclose, thermal trip and under-voltage relay trip settings for

single-phase air-conditioner loads. WECC [5] and IEEE [6] documents were used to help

determine initial protection settings the LMWG can use for initial simulations.

Although not discussed in Table III of [6], John Kueck had indicated via personal

correspondence with the SS-38 working group for their 2014 NPCC UFLS Assessment that 50%

of industrial and commercial motors restart at 0.90 pu voltage within a few cycles via Energy

Management systems. An additional 0.05 pu voltage was added to the restart voltage (for a total

of 0.95 pu) to account for voltage drops within the commercial and industrial facilities

themselves. The overall initial protection settings can be found in Table 9 to Table 11.

Table 9: 3-phase motor load protection settings (For Motors A, B and C). Tables III and VI in [6]

Parameter Value

Vtr1A - U/V Trip1 V (pu) 0.7

Ttr1A - U/V Trip1 Time (sec) 0.032

Ftr1A - U/V Trip1 fraction 0.5

Vrc1A - U/V Trip1 reclose V (pu) 1.0

Trc1A - U/V Trip1 reclose Time(sec) 999 (no restart)


Ttr2A - U/V Trip2 Time (sec) 0.032



Trc2A - U/V Trip2 reclose Time(sec) 0.032

Table 10: 3-phase industrial motor load protection settings (For Industrial motors A, B and C). Table VII in

[6] Parameter Value


Ttr1A - U/V Trip1 Time (sec) 2.0 (ride through faults < 2s duration)



Trc1A - U/V Trip1 reclose Time(sec) 5 (restart after 5s via EMS)


Ttr2A - U/V Trip2 Time (sec) 2.0 (ride through faults < 2s duration)



Trc2A - U/V Trip2 reclose Time(sec) 5 (restart after 5s via EMS)

Table 11: Single-phase A/C motor load protection settings (For motor D). [4]

Parameter Value

Frst - fraction of motors capable of restart 0

Vrst - voltage at which motors can restart (p.u.) 0.9

Vc1of f - Voltage at which contactors start dropping out (p.u.) 0.45

Vc2off - Voltage at which all contactors drop out (p.u.) 0.35

Vc1on - Voltage at which all contactors reclose (p.u.) 0.5

Vc2on - Voltage at which contactors start reclosing (p.u.) 0.4

Tth - compressor motor heating time constant (sec) 10

Th1t - temperature at which compressor motor begin tripping 1.3



Parameter Value

Th2t - temperature at which compressor all motors are tripped 4.3

Fuvr - fraction of compressor motors with U/V relays 0

UVtr1 - 1st voltage pick-up (p.u.) n/a

Ttr1 - 1st definite time voltage pickup (sec) n/a

UVtr2 - 2nd voltage pick-up (p.u.) n/a

Ttr2 - 2nd definite time voltage pickup (sec) n/a

Chapter 5 Benchmarking Tests


5. Benchmarking Tests

Using the initial parameters established in Section 4 above, the LMWG began benchmarking the

load model. Where possible, the load models were benchmarked using actual system events. Of

particular interest are any FIDVR events, or where an event led to inadvertent load loss. Events

which result in inadvertent load loss will help refine the protection settings, while FIDVR events

will help refine the motor load distribution.

5.1 Motor Load Protection Settings

The LMWG used the following procedure to benchmark system events:

1. If possible, obtain a real-time snapshot of the system prior to the event.

If this is not possible, modify any available offline base-case to match pre-

contingency conditions such as generation dispatch, demand level, bus voltages, etc.

Apply the NPCC SS-38 Working Group Governor Response Calibration Procedure

for Dynamics Simulations to establish reasonable aggregate governor frequency

response for a study area.

2. Obtain available PMU data and other recorded data (e.g. bus voltages, real and reactive

flows, frequency) from the actual system event.

3. Simulate the event using the standard load model used for transient simulations.

4. Simulate the event using a composite load model which takes into account the effects that

motor load may have on the system.

5. Benchmark the simulated responses with the recorded data.

6. Adjust load data as necessary to obtain a more accurate response. This can include

adjusting the various under-voltage motor load protection settings to obtain a more

accurate system response (e.g. bus voltages, flows, observed load loss).

5.2 System Events

The system events within NPCC which were used to benchmark the load model are as follows:

For Ontario:

o May 25, 2005: A 3-phase to ground fault at a 500 kV station resulted in

approximately 2,300 MW of inadvertent load loss.

o January 30, 2007: A 3-phase to ground fault at a 230 kV station resulted in

approximately 1,500 MW of inadvertent load loss.

o July 5, 2010: A breaker explosion at a 230 kV station that resulted in the loss of about

1,550 MW of load, 650 MW of which was inadvertent. Five phase-to-ground faults

and one three-phase fault occurred within four seconds.

o November 26, 2010: A phase-to-phase fault on a 230 kV circuit resulted in

approximately 500 MW of indirect load loss.

o November 30, 2010: A phase-to-phase fault on a 230 kV circuit resulted in

approximately 545 MW of indirect load loss.

o January 24, 2011: A phase-to-ground fault on a 230 kV circuit that resulted in the

inadvertent loss of about 200 MW of load.



o February 19, 2011: A 3-phase fault on the 230 kV system which resulted in the

approximately 720 MW of inadvertent load loss.

o March 18, 2011: Explosive failure of transformer that resulted in the loss of about

640 MW of load, 608 MW of which was inadvertent.

o March 16, 2015: A failed insulator on a 230 kV circuit out of a station resulted in

about 700 MW of sympathetic load loss. Three phase-to-phase and two phase-to-

ground faults occurred within fifteen seconds.

For New England:

o May 25, 2014: A 345 kV single-phase to ground fault at a station, followed by the

loss of two 345 kV lines connected to a generation station resulted in the loss of all

generation at the Station.

For New York:

o There are no recent recorded events in NY that involved delayed voltage recovery or

inadvertent load loss. Thus, the NY load representation cannot be benchmarked

against actual events at this time.

For Québec:

o July 3, 2013: A forest fire on a line between two 735 kV substations, combined with

operator error led to a 7 minute long event which resulted in the loss of 3,950 MW of

load, loss of 3,200 MW of exports, tripping of 12 SVC and 1 condenser.

5.3 Ontario

For the events in Ontario, real-time pre-contingency snapshots were available starting from the

July 5, 2010 event. For the two events prior to this, approximate pre-contingency cases were

created. As all of the events of interest in Ontario resulted in some sort of load loss, motor load

protection settings were modified in the composite load model to determine a set of parameters

which provide the most accurate results across all events.

Table 12 lists the different sets of protection settings that were used for the Ontario events.

Scenarios 1 and 3 are quite similar with the main difference being the 3-phase motor under-

voltage trip fractions at each under-voltage trip setting. The protection settings in Scenario 2 are

based on updated parameters that the WECC LMTF has been using.

Table 12: Protection settings tested for Ontario benchmarking tests.

Motor Type Parameter Value

Scenario 1 Scenario 2 Scenario 3

3-phase Motors A, B and C

Vtr1A – U/V Trip1 V (pu) 0.7 0.7 (A,C)/0 (B) 0.7

Ttr1A – U/V Trip1 Time (sec) 0.16 (A)/0.032 (B,C) 0.032 (A,C)/ 999 (B) 0.16 (A)/0.032 (B,C)

Ftr1A – U/V Trip1 fraction 0.65 0.25 (A,C)/0.5 (B) 0.5

Vrc1A – U/V Trip1 reclose V (pu) 1 1 (A,C)/999 (B) 1

Trc1A – U/V Trip1 reclose Time(sec) 999 999 (A,C)/999 (B) 999

Vtr2A – U/V Trip2 V (pu) 0.5 0.5 (A,C)/0.55 (B) 0.5

Ttr2A – U/V Trip2 Time (sec) 0.16 (A)/0.032 (B,C) 0.032 0.16 (A)/0.032 (B,C)

Ftr2A – U/V Trip2 fraction 0.35 0.75 (A,C)/0.5 (B) 0.5

Vrc2A – U/V Trip2 reclose V (pu) 0.95 0.7 0.95

Trc2A – U/V Trip2 reclose Time(sec) 0.032 0.032 0.032

3-phase Industrial Motors A, B and C

Vtr1A – U/V Trip1 V (pu) 0.7 0.7 0.7

Ttr1A – U/V Trip1 Time (sec) 0.032 0.032 0.032

Ftr1A – U/V Trip1 fraction 0.5 0.25 0.5

Vrc1A – U/V Trip1 reclose V (pu) 1 1 1

Trc1A – U/V Trip1 reclose Time(sec) 999 999 999



Vtr2A – U/V Trip2 V (pu) 0.5 0.5 0.5

Ttr2A – U/V Trip2 Time (sec) 0.032 0.032 0.032

Ftr2A – U/V Trip2 fraction 0.5 0.75 0.5

Vrc2A – U/V Trip2 reclose V (pu) 0.95 0.7 0.95

Trc2A – U/V Trip2 reclose Time(sec) 999 999 999

Single-phase A/C Motor Load

Vstall – compressor stall voltage at base condition (p.u.) 0.5875 0.5 0.7

Frst – fraction of motors capable of restart 0.2 0.2 0.5

Vrst – voltage at which motors can restart (p.u.) 0.9 0.9 0.9

Vc1of f – Voltage at which contactors start dropping out (p.u.) 0.55 0.55 0.55

Vc2off – Voltage at which all contactors drop out (p.u.) 0.45 0.45 0.45

Vc1on – Voltage at which all contactors reclose (p.u.) 0.65 0.65 0.65

Vc2on – Voltage at which contactors start reclosing (p.u.) 0.55 0.55 0.55

Tth – compressor motor heating time constant (sec) 10.5 10 10

Th1t – temperature at which compressor motor begin tripping 0.7 0.9 0.9

Th2t – temperature at which compressor all motors are tripped 1.5 4.3 1.5

Fuvr – fraction of compressor motors with U/V relays 0 0 0

Uvtr1 – 1st voltage pick-up (p.u.) 0.8 0.8 0.8

Ttr1 – 1st definite time voltage pickup (sec) 0.2 0.2 0.2

Uvtr2 – 2nd voltage pick-up (p.u.) 0.9 0.9 0.9

Ttr2 – 2nd definite time voltage pickup (sec) 5 5 5

Table 13 compares the observed and simulated load loss for the various protection settings

tested.

Table 13: Simulated vs. Observed load loss for Ontario events.

Event Tool Used Load Condition

Used Observed Load

Loss (MW)

Simulated Load Loss (MW)

Scenario 1 Scenario 2 Scenario 3

May 25, 2005 DSA Powertech Summer 2,300 TBD TBD TBD

January 30, 2007 DSA Powertech Winter 1,500 1,370 970 1,390

July 5, 2010 DSA Powertech Summer 1,550 1,620 1,316 1,780

July 5, 2010 PSSE Summer 1,550 TBD TBD TBD

November 26, 2010 DSA Powertech Light Load 500 998 388 776

November 30, 2010 DSA Powertech Light Load 545 720 266 562

January 24, 2011 DSA Powertech Winter 200 TBD TBD TBD

February 19, 2011 DSA Powertech Winter 720 889 334 728

March 18, 2011 DSA Powertech Winter 608 585 251 644

March 16, 2015 DSA Powertech Winter 700-900 1,330 550 1,050

March 16, 2015 PSSE Winter 700-900 1,485 601 1,198

Based on the results above, the protection settings in Scenario 3 seem to provide the most

accurate results from a load loss point of view. The voltage responses obtained using the

composite load model are also more accurate when compared to those obtained using the static

ZIP model. Sample responses can be found in Figure 4 to Figure 7.



Figure 4: A 500 kV bus voltage for July 5, 2010 benchmarking tests.

Figure 5: A 230 kV bus voltage for November 26, 2010 benchmarking tests.



Figure 6: A 500 kV bus voltage for November 30, 2010 benchmarking tests.

Figure 7: A 500 kV bus voltage for March 16, 2015 benchmarking tests.



5.4 New York

For testing, the NY CMLD composite load model used the percentages of motor and electronic

loads from Table 6, along with NYPA and National Grid industrial loads. The protection settings

parameters were based on WECC testing (Table 9 - Table 11). The 2014 NY Area Transmission

Review (ATR) dynamics basecase (Summer Peak 2019) was modified as follows in order to get

the network to converge using the Siemens PTI PSS®E (Rev. 32) software:

Any NY load that was below 80% load power factor was raised to 85%.

A significant portion of the loads in NY are modeled at the distribution voltage level (e.g.

34.5 kV). Therefore, distribution transformer and feeder reactance and resistance in the

CMLD model were set to zero. This is an area that needs further attention as the NY load

model is developed by load bus. A possible solution is to add the CMLD model for each

individual load bus and adjust the transformer/feeder parameters appropriately.

Some Consolidated Edison 13.8 kV load buses and radial 34.5 kV circuits in rural areas

were equivalenced to a higher voltage to get the network to converge. Again, this needs

further attention.

According to Table 9, the under-voltage trip time (Ttr1A & Ttr2A) is 0.032 sec (2 cycles)

for Motors A, B and C with the under-voltage trip setting at 0.7 and 0.5 pu, respectively.

For normal design criteria faults in NY, the fault clearing times run from 3 to 7 cycles.

The trip time of 2 cycles occurs during the fault and any load bus under 0.7 pu trips 50%

of its motor A, B & C load (UV trip fraction from Table 9). For many of the NY faults,

motor load is tripped on the normal design faults due to voltage. For example, a 3-phase

fault at a 345 kV station will result in the tripping of more than 100 MW of motor load.

This is an approximation as Siemens PTI lacks a tool to precisely determine the amount

of motor load that has tripped during a simulation. This is not just specific to New York

as other areas have seen similar responses.

As noted previously, there are no recorded events in NY to use as a benchmark for motor load

tripping after faults. Therefore, sensitivity simulations were run to compare the system response

with under-voltage trip times of 2 and 6 cycles. The current NY dynamics basecase takes a

longer time (~3 hrs) to simulate a fault than the ZIP (<30 mins) and CLOD (<30 mins) models

due to the complicated motor load representation and difficulties finding a network solution

(numerical issues) on a 15 second run even with the above modifications.

A comparison of system response with the static, complex and composite load model with two

different trip times (2 vs. 6 cycles) is provided in



Figure 8.



Figure 8: Voltage Response for a 3 Phase fault on a 345 kV line in New York.

––- ZIP Model ----- CLOD Model ----- CMLD @ UV trip of 2 cycles ----- CMLD @ UV trip of 6 cycles

Chapter 6 Preliminary Composite Load Model


6. Preliminary Composite Load Model

Requirement 2.4.1 of NERC Standard TPL-001-4 on Transmission System Planning

Performance Requirements states the following regarding load modeling when performing

Planning Assessments:

System peak Load for one of the five years. System peak Load levels shall include a

Load model which represents the expected dynamic behavior of Loads that could

impact the study area, considering the behavior of induction motor Loads. An

aggregate System Load model which represents the overall dynamic behavior of the

Load is acceptable.

To help comply with this requirement, the LMWG has listed preliminary composite load models

for each area to use. The user of these load models must keep in mind that these load models are

very preliminary, as the LMWG has not yet had the chance to fully test and benchmark each one.

These models will be further refined over time as the LMWG further performs benchmarking

tests with actual system events.

6.1 Ontario

Based on the benchmarking tests in Ontario, the following parameters should be used for

transient simulations involving a composite load model in the Ontario system:

Seasonal and zonal motor load breakdown for Ontario according to Table 4: Load

Condition Zone

Motor Load Breakdown w/o Industrial Load Industrial Load Breakdown

Motor A Motor B Motor C Motor D Electronic Motor A Motor B Motor C Motor D Electronic

Peak

Load

Bruce 9.0% 3.83% 9.23% 3.8% 1.9% 29.7% 30.0% 16.6% 0.0% 0.0%

East 21.2% 4.45% 13.77% 20.5% 8.4% 28.5% 28.6% 18.1% 0.0% 0.0%

Essa 17.9% 4.03% 11.52% 24.8% 9.5% 30.1% 32.1% 16.1% 0.0% 0.0%

Niagara 21.1% 3.51% 12.83% 22.5% 8.0% 26.7% 27.1% 18.3% 0.0% 0.0%

Northeast 17.8% 4.60% 13.61% 13.3% 10.5% 30.3% 30.8% 13.5% 0.0% 0.0%

Northwest 17.2% 5.34% 16.45% 12.0% 9.5% 27.5% 37.3% 20.4% 0.0% 0.0%

Ottawa 19.9% 3.39% 11.53% 23.2% 9.7% 24.6% 26.3% 15.9% 0.0% 0.0%

Southwest 20.5% 3.66% 11.91% 21.6% 8.8% 26.7% 27.0% 15.5% 0.0% 0.0%

Toronto 22.2% 2.64% 11.36% 21.6% 8.9% 30.1% 30.1% 17.8% 0.0% 0.0%

West 21.5% 4.75% 13.86% 20.5% 8.1% 32.6% 33.2% 17.7% 0.0% 0.0%

Light

Load

Bruce 6.1% 6.48% 15.62% 1.7% 3.2% 27.1% 30.0% 16.7% 0.0% 0.0%

East 5.2% 8.74% 21.99% 7.9% 12.1% 26.3% 29.3% 18.6% 0.0% 0.0%

Essa 3.4% 9.26% 18.02% 10.1% 14.1% 28.1% 32.6% 16.1% 0.0% 0.0%

Niagara 2.9% 4.73% 14.27% 4.9% 7.7% 24.4% 27.9% 19.3% 0.0% 0.0%

Northeast 2.4% 8.24% 15.20% 9.6% 11.9% 29.9% 30.3% 14.7% 0.0% 0.0%

Northwest 3.8% 8.77% 19.92% 8.9% 11.1% 27.3% 36.5% 22.7% 0.0% 0.0%

Ottawa 3.6% 8.05% 20.37% 8.7% 15.4% 23.1% 25.4% 15.4% 0.0% 0.0%

Southwest 3.8% 7.94% 19.38% 8.3% 12.8% 24.7% 26.1% 15.3% 0.0% 0.0%

Toronto 3.6% 6.28% 21.16% 7.3% 14.1% 28.2% 30.7% 18.3% 0.0% 0.0%

West 5.6% 9.17% 21.64% 7.9% 11.6% 32.0% 33.5% 17.6% 0.0% 0.0%

Winter

Peak

Load

Bruce 5.7% 5.31% 16.51% 0.8% 1.5% 28.4% 30.4% 16.7% 0.0% 0.0%

East 4.1% 4.11% 22.77% 3.1% 5.5% 27.7% 29.0% 18.1% 0.0% 0.0%

Essa 3.0% 3.53% 19.33% 3.7% 6.5% 29.2% 32.7% 16.2% 0.0% 0.0%



Niagara 4.4% 3.57% 25.12% 3.2% 5.8% 25.8% 27.1% 18.0% 0.0% 0.0%

Northeast 2.0% 3.02% 17.07% 3.6% 5.4% 30.7% 30.3% 12.6% 0.0% 0.0%

Northwest 3.2% 3.55% 19.29% 3.2% 4.7% 28.1% 36.7% 19.3% 0.0% 0.0%

Ottawa 3.6% 2.97% 20.78% 3.1% 5.7% 24.2% 26.3% 15.7% 0.0% 0.0%

Southwest 3.3% 2.88% 20.19% 3.2% 5.8% 26.1% 27.1% 15.5% 0.0% 0.0%

Toronto 4.0% 2.70% 25.08% 3.2% 5.8% 29.6% 30.5% 17.7% 0.0% 0.0%

West 4.7% 4.37% 22.10% 3.1% 5.5% 32.6% 33.4% 17.6% 0.0% 0.0%

Three phase motor parameters according to Table 7: Parameter MA MB MC IA IB IC

LF - Loading factor 0.75 0.75 0.75 0.85 0.85 0.85

Pf - Power Factor 0.78 0.78 0.78 0.89 0.89 0.89

Ls - Synchronous reactance 1.8 1.8 1.8 3.1 3.1 3.1

Lps - Transient reactance 0.12 0.19 0.19 0.2 0.2 0.2

Lpps - Sub-transient reactance 0.104 0.14 0.14 0.165 0.165 0.165

Ra - Stator resistance 0.04 0.03 0.03 0.01 0.01 0.01

Tpo - Transient open circuit time constant 0.095 0.2 0.2 0.8 0.8 0.8

Tppo - Sub-transient open circuit time constant 0.0021 0.0026 0.0026 0.0026 0.0026 0.0026

H - Inertia constant 0.05 0.5 0.15 0.15 1 0.2

Etrq - Torque speed exponent 0 2 2 0 2 2

Single phase A/C motor parameters according to Table 8: Parameter Value Parameter Value

Tstall - stall delay (sec) 0.033 Np1 - real power exponent for running state 1 1

Trestart - restart delay (sec) 0.4 Kq1 - reactive power constant for running state 1 6

Tv - voltage input time constant (sec) 0.02 Nq1 - reactive power exponent for running state 1 2

Tf - frequency input time constant(sec) 0.05 Kp2 - real power constant for running state 2 12

CompLF - compressor load factor (p.u.) 1 Np2 - real power exponent for running state 2 3.2

CompPF - compressor power factor 0.97 Kq2 - reactive power constant for running state 2 11

Vstall - compressor stall voltage at base condition (p.u.) 0.7 Nq2 - reactive power exponent for running state 2 2.5

Rstall - compressor motor resistance (p.u.) 0.124 Vbrk - compressor motor "breakdown" voltage (p.u.) 0.86

Xstall - compressor motor stall reactance (p.u.) 0.114 CmpKpf - real power constant for freq dependency 1

LFadj - Load factor adjustment to the stall voltage 0.3 CmpKqf - reactive power constnt for freq dependency -3.3

Kp1 - real power constant for running state 1 0

Protection settings from Scenario 3 in Table 12: Motor Type Parameter Value

3-phase Motors A, B

and C

Vtr1A – U/V Trip1 V (pu) 0.7

Ttr1A – U/V Trip1 Time (sec) 0.16 (A)/0.032 (B,C)

Ftr1A – U/V Trip1 fraction 0.5

Vrc1A – U/V Trip1 reclose V (pu) 1

Trc1A – U/V Trip1 reclose Time(sec) 999


Ttr2A – U/V Trip2 Time (sec) 0.16 (A)/0.032 (B,C)


Vrc2A – U/V Trip2 reclose V (pu) 0.95

Trc2A – U/V Trip2 reclose Time(sec) 0.032

3-phase Industrial

Motors A, B and C


Ttr1A – U/V Trip1 Time (sec) 0.032


Vrc1A – U/V Trip1 reclose V (pu) 1



Ttr2A – U/V Trip2 Time (sec) 0.032


Vrc2A – U/V Trip2 reclose V (pu) 0.95


Single-phase Vstall – compressor stall voltage at base condition (p.u.) 0.7



Motor Type Parameter Value

A/C Motor Load

Frst – fraction of motors capable of restart 0.5

Vrst – voltage at which motors can restart (p.u.) 0.9

Vc1of f – Voltage at which contactors start dropping out (p.u.) 0.55

Vc2off – Voltage at which all contactors drop out (p.u.) 0.45

Vc1on – Voltage at which all contactors reclose (p.u.) 0.65

Vc2on – Voltage at which contactors start reclosing (p.u.) 0.55

Tth – compressor motor heating time constant (sec) 10

Th1t – temperature at which compressor motor begin tripping 0.9

Th2t – temperature at which compressor all motors are tripped 1.5

Fuvr – fraction of compressor motors with U/V relays 0

Uvtr1 – 1st voltage pick-up (p.u.) 0.8

Ttr1 – 1st definite time voltage pickup (sec) 0.2

Uvtr2 – 2nd voltage pick-up (p.u.) 0.9

Ttr2 – 2nd definite time voltage pickup (sec) 5

6.2 New England

The CMLD parameters used for New England are as follows:

Power Electronic loads (Adjustable Speed Drives and electronic equipment):

Vd1: voltage at which electronic load start to drop out: 0.70 pu

Vd2: voltage at which all electronic load drop out: 0.60 pu

Commercial 3 phase Air Conditioners (Motor A <250 HP):

Vtr1 - U/V Trip1 V (pu) 0.70 pu

Ttr1 - U/V Trip1 Time (sec) 0.033 sec (2 cycles)

Ftr1 - U/V Trip1 fraction 0.20

Vrc1 - U/V Trip1 reclose V (pu) 1.0 pu

Trc1 - U/V Trip1 reclose Time (sec) 999 sec (no restart)




Vrc2 - U/V reclose V (pu) 0.70 pu

Trc2 - U/V reclose Time (sec) 0.033 s

Commercial 3 phase Pumps (Motor B)





Trc1 - U/V Trip1 reclose Time (sec) 0.033s




Vrc2 - U/V Reclose V (pu) 0.95 pu

Trc2 - U/V Reclose Time (sec) 999 sec (no reclose)



Commercial 3 phase Fans (Motor C):





Trc1 - U/V Trip1 reclose Time (sec) 999 sec (no restart)





Trc2 - U/V reclose Time (sec) 0.033 s

Industrial Motors A B or C (>250 HP) (Kueck) Table VI:


Ttr1 - U/V Trip1 Time (sec) 2.0 sec (will ride through faults less than 2s duration)

Ftr1 - U/V Trip1 fraction 0.5 (assume half trip at 80% voltage)


Trc1 - U/V Trip1 reclose Time (sec) 5 sec ( restart after 5s via EMS)


Ttr2 - U/V Trip2 Time (sec) 2.0 sec (will ride through faults less than 2s duration)

Ftr2 - U/V Trip2 fraction 0.5 (assume half trip at 75% voltage)


Trc2 - U/V reclose Time (sec) 5 sec ( restart after 5s via EMS)

Single Phase Airconditioners (Motor D):

Stall Voltage: 30% of nominal voltage

Undervoltage contactor dropout: o VC1off (0.4pu): 50% drop out at 0.30 pu voltage, o VC2off (0.3pu): 50% drop out at 0.20 pu voltage.

Contactor Reclose: o VC1on (0.70 pu): 50% close back in at 0.70 pu voltage o VC2on (0.65 pu): 50% close back in at 0.65 pu voltage.

Stall time: 2 cycle (0.033s) after stall voltage is encountered. (Kueck)

Fraction of Motors that restart: 20%

Restart Voltage: 0.90 pu

Restart Time: 0.033s (sec)

Thermal Relay - Compressor motor heating time constant, sec: 15

Thermal Relay - Temperature at which compressor motors begin tripping, p.u.: 0.7

Thermal Relay - Temperature at which all motors are tripped, p.u: 1.9

Under-voltage relay - Fraction of motors with under-voltage relays: 0%

Under-voltage relay - First under-voltage pickup level, p.u. : N/A

Under-voltage relay - Second under-voltage pickup level, p.u. : N/A

Under-voltage relay - First definite time for under-voltage trip, sec. : N/A

Under-voltage relay - Second definite time for under-voltage trip, sec. : N/A



6.3 New York

In the 2014 Intermediate ATR of the New York State Bulk Power Transmission System, stability

analysis was evaluated against the peak load base case and high peak load sensitivity case with

the CLOD complex load model consistent with the NERC standard mentioned above. The

CLOD model was used due to concerns with the applicability of the CMLD model. The power

flow model with distribution transformers needs to be represented accurately to include the R

and X parameters, depending upon system load level and whether the dynamic load model is

placed on the high voltage bus or the distribution bus. The system representations used in this

transmission review were developed based on the NPCC 2013 Base Case Development (BCD)

library and the NYISO 2014 FERC 715 filing power flow models updated with the NYISO 2014

Load and Capacity Data.

The dynamic loads were broken down by zone from Table 6. These dynamic load modeling

assumptions result in a breakdown that is approximately 12-13% large motor (Motor B), 45-52%

small motor (Motor A, C & D) and 12% as constant power in NYCA. The remaining load on the

bus after applying these specified percentages is varied as the voltage is raised to the second

power. Long Island provided their own CLOD model that was prepared by an industry

consultant and by referencing WECC materials. Given the customer base and the lack of industry

on Long Island, they assume that there are no ‘large motors’. For peak load, they assume that the

predominant load consists of air conditioning load, which accounts for the large percentage

(75%) of ‘small motors’ in their CLOD model. This dynamic load model was tested on the same

normal design and extreme contingencies as the static load model for the 2019 peak and high

peak load cases.

The stability simulations show no load loss or stability issues for the same normal design

contingencies as the static load model. The dynamic load model was also used when testing

extreme contingencies. It was found that 8 of the 55 extreme contingencies were unable to solve

due to local low voltage issues; all contingencies converged and were stable using the static load

model. With the exception of the eight contingencies, all extreme contingencies are stable when

using the dynamic load model (CLOD). In all of the evaluated cases and conditions tested, the

affected area is confined to the NYCA system.

Some additional tests were done on the Central East (CE) and Upstate NY (UPNY) margin

transfer cases, as the base case comparison plots of the static (ZIP) versus dynamic (CLOD)

model showed slight differences. An example of the basecase is shown here of the voltage

response of a 345 kV bus which is near the fault (Fig. 9).



Figure 9: Basecase – Voltage Response for 3 Phase fault on a 345 kV line in New York.

The comparison plot with the Central East margin case (Fig. 10) shows that the induction motor

response causes slower voltage recovery and larger oscillations than the static load model. It is

recommended to run contingencies on margin transfer cases to see the more pronounced effects

of motor load.

––- ZIP Model ----- CLOD Model



Figure 10: CE Margin Case - Voltage Response for 3 Phase fault on a 345 kV line in New York.

––- ZIP Model ----- CLOD Model


Chapter 7 Installation of Data Recorders

7. Installation of Data Recorders

For each of the benchmarked events, obtaining data recorded from devices such as phasor

measurement units (PMU) or power system data recorders (PSDR) was essential. These devices

record data at a much higher frequency (e.g. can be > 6 samples/second) than the data that can be

obtained through SCADA systems (e.g. 1 sample every 2 - 4 seconds).

For future PMU installations, it recommended that consideration be given to locations where

distribution load serving transformers exist. Transmission level substations that contain load

serving transformers would be advantageous for installation of PMUs because both transmission

and load data can be captured.

For existing PMU installations where distribution load data is available but not monitored,

consideration should be given to adding these data points to PMU inputs.

Chapter 8 Next Steps


8. Next Steps

With the majority of the work complete to improve the accuracy of dynamic load model data

through an end-use survey, the next tasks for the LMWG to complete include the following:

1. Finalize the end-use load model for any areas which have not yet done so.

2. Continue performing simulations to gain more experience with composite load models.

3. Where possible, continue benchmarking the load models with actual system events. Of

particular interest are any FIDVR events, or where an event led to inadvertent load loss.

Events which result in inadvertent load loss will help refine the protection settings, while

FIDVR events will help refine the motor load distribution. Several system events within

each area have already been identified. Where applicable, update any benchmarking tests

using updated composite load models.

4. Once the load models have been benchmarked, the LMWG will explore the potential

impact that dynamic load models may have on inter-area dynamics, and transfer

capabilities across the system.

5. Keep up to date with any further developments with the composite load model. The

WECC LMTF is continually improving the composite load model, so the LMWG should

be mindful of these changes.

6. Investigate the feasibility and cost effectiveness of installing additional load monitoring

equipment, such as PMUs and PSDRs, to aid in the benchmarking of dynamic load

models. The LMWG will also investigate the most ideal locations to install such devices.


Chapter 9 References

9. References

[1] http://www.powerauthority.on.ca/power-planning/long-term-energy-plan-2013

[2] W. Gifford, J. Lopes, C. Driscoll, N. Ghosh, A. Kanungo, J. Metoyer, T. Ledyard, “End-Use

Data Development for Power System Load Model in New England – Methodology and Results”

April 2014

[3] WECC Model Validation Working Group, “Composite Load Model for Dynamic

Simulations” June 2012

[4] R. Bravo, J. Wen, D. Kosterev, B. Price, R. Yinger, “WECC Air Conditioner Motor Model

Test Report”

[5] J.D. Kueck, “Voltage Influence on Typical Protection and Controls for Motors, Power

Electronics, and Other Common Loads” February 2011

[6] J.D. Kueck, “Voltage Sag and Recovery Influence of Modeling Motor Loads”, IEEE PES

T&D Conference, April 2014

http://www.powerauthority.on.ca/power-planning/long-term-energy-plan-2013

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