Reduced WECC and EI Models for

Education and Research

Yidan Lu1, Yin Lei1, Gefei Kou1, Denis Osipov1, Joe Chow2, Yilu Liu1, Kai Sun1 and Kevin Tomsovic1

1The University of Tennessee, Knoxville 2Rensselaer Polytechnic Institute

Introduction and Backgrounds

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1. Rapid expansion of transmission grid and increase of renewable have made the current standard power system models outdated forresearch.

2. Implementation of Phasor Measurement Units (PMUs) enhanced power system observability and allow measurement based model reductions for construction of a Large Scale Testbed.

3. Large Scale Testbed contains reduced models at different resolution levels to serve as platform to address future power gird issues, including power transfer with HVDC overlay and security assessment with high renewable penetration.

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Frequency Response of Montana Generation Trip comparison Between Cases

Green : Fnet data recording

Blue: Simulation Results of Case I (no wind

penetration)

Red: Simulation Results of Case II (12% wind

penetration)

Black: Simulation Results of Case III (22% wind penetration)

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Time Domine Frequency Response after DC filtering

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2 4.4 4.6 4.8 50

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Single-Sided Amplitude Spectrum of Frequency Response after DC filtering

Case I Oscillation Mode

Case II Oscillation Mode

Case III Oscillation Mode

FNET Record Oscillation Mode

Case I Oscillation Mode

Case II Oscillation Mode

Case III Oscillation Mode

Fnet Record Oscillation Mode

Early Achievements

Fig. 1 Large Scale Test-bed

Interconnection Area Generation Capacity (GW)EI Central 434.23EI Northwestern 35.08EI Northeastern 81.89EI Florida 39.54

WECC Washington 77.60WECC Wyoming 11.88WECC New Mexico 27.28WECC California 37.55ERCOT Northern 15.64ERCOT Houston 9.74ERCOT Southern 1.99ERCOT Western 5.98

Fig. 2 Power System Clustering

Table I Dynamic Cluster Generation Capacity

• Testbed of highly reduce networks (Fig. 1)

is developed by generation aggregation.

Measurements-based EI reduced system

(Fig.2) is developed by clustering.

Development of EI Models for Future Applications

Fig. 4 Control Area based

Reduced EI Structure

• EI models at different resolutions developed

with steady state or dynamic equivalence.

• A 21-bus (Fig. 3) reduced EI model preserving

static and dynamic equivalences was

developed via application of measurement

based K-mean clustering algorithm.

• A 266-bus control area based reduced EI

model (Fig. 4) was constructed for HVDC

based on control area recognition.

• A 446-bus EI model (Fig. 5) with steady state

equivalence was later completed to form part of

the North America Power Grid Testbed.

A detailed 2030 EI system (Fig. 6)

with 17% of wind penetration was

also proposed.

Fig. 3 Measurement based

reduced EI Structure

Fig. 5 DynRed Reduced EI Model

Fig. 6 The 2030 EI Model with 70,000+ buses

WECC Model Validation with Renewable Integration

Case Number Bus Number Total Generation Wind Generation Wind Penetration Transfer LimitDetailed Case 15600 154 GW Not Applicable Not Applicable 4800MWCase I 181 61 GW 0GW 0% 4620.5MWCase II 197 61 GW 7.37GW 12.08% 4593.5MWCase III 197 61 GW 13.52GW 22.16% 4445.8MW

Fig. 8 Time Domain Frequency Response Fig. 9 FFT Analysis of Oscillation Mode

Table II Comparison of COI Transfer Limit Among Cases

Fig. 7 WECC System with Wind Integration

• Simplified WECC systems

developed with different

levels of wind

penetrations.

• Locations and capacity of

wind turbines determined

according to prototype

data.

• Simplified WECC systems

preserve equivalence in

frequency responses and

COI Transfer capability.

HVDC Interconnection of North America Power Grid Conclusions

1. Mid-size reduced system

developed respectively for

WECC, EI and ERCOT .

2. Around 1000-bus North

America Power grid testbed

with 50% wind penetration is

ready for use .

3. Control schemes to avoid

voltage collapse and

islanding will be validated

using this testbed

4. This testbed will serve future

academy and research

purposes.

Fig. 10 Interconnection of North America System using Back to Back HVDC

EI to WECC Back to Back HVDC Connection

Location DC Volt. EI to WECC Capacity WECC to EI Capacity

McNeil, Saskatchewan 42kV 200MW 75MW

Mile city Montana 82kV 200MW 200MW

Stegall Nebraska 57kV 0MW 166MW

Virginia Smith Nebraska 50kV 200MW 200MW

EI to ERCOT Back to Back HVDC Connection

Location DC Volt. EI to Texas Capacity Texas to EI Capacity

Oklaunion, Texas 82kV 200MW 200MW

Welsh, Texas 162kV 600MW 600MW

WECC to ERCOT Back to Back HVDC Connection

Location DC Volt. WECC to TexasCapacity

Texas to WECC Capacity

Blackwater, New Mexico 57kV 210MW 0MW

Eddy New Mexico 82kV 200MW 200MW

Table III Location and Capacity of Back to Back

HVDC Connection in North America Power Grid