China-US S&T Strategic Policy Workshop on Smart Grid

China-US S&T Strategic Policy Workshop on Smart Grid

Yingduo Han, Chao Lu Dept. of EE, Tsinghua Univ. 5/30/2013, Washington DC

Analyses and Control of the Bulk Power System based on Synchronized Phasor Measurement System

1


Outlines

PMU/WAMS Developments

Two Typical Applications based PMU/WAMS

Roadmap and Future Work about PMU/WAMS Applications

New Thoughts based on Smart Grid Concepts

2


1. Current PMU Locations and Plan in North American

3


• PMUs were installed in more than 1500 substations and power plans. (12/12)

• WAMS master stations are deployed in all provincial dispatch centers (>40).

4

Northwest:272

Northeast:291

Central:341

North:312

East:147

PMU/WAMS Deployed in China


PMU/WAMS based Applications in China

5

Angle/frequency/voltage/flow monitoring

Wide-area Monitoring

Stability Alarming

Decision Support

Advanced Control & Protection

Frequency regulation monitoring

Oscillation detection

Offline disturbance analysis

Disturbance detection

Oscillation identification and alarming

Voltage/angle/frequency trending and Stability alarming

Wide-area visualization

Improved or linear state estimation

Online model & parameter identification

Steady state stability assessment and decision optimization

Oscillation related power flow optimization

Advanced remedial actions and protections

Wide-area Damping control

Oscillation source control

Transient stability assessment and optimization

Planned system separation

Transient/voltage stability coordinated control

Renewable energy integration wide-area control

Technical challenging


Case 1: Northeast China Power System Large Disturbances Field Tests (2003)

6 2008-9-8

500kV substation bus, artificial three-phase

grounding short circuit


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Monitoring using PMU in

master stations


Simulation Model and Parameter Modification according to PMU Recordings

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Load Model and Parameters

Group 1 Group 2 Group 3 Group 4

East HLJ Power Transfer Limit（MW）

615 1200 1205 1210

HLJ to JL Limit （MW）

843 1236 1476 1387

JL to LN Limit （MW）

1500 1968 1985 1750

Group 1：50% constant impedance+50% motor Group 2：40% constant impedance+60% constant power

Group：the motor stator impedance is changed from 0.295 to 0.12 Group 4：IEEE-6 type motor


Online Dominant Load Parameters Identification

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Dominant parameter selection State equation

to Volterra model

K-L orthogonal transform

Pattern classification

Steady state measurement

Dynamic state measurement

Reduced order Volterra model

based LS

Online fast pattern

recognition

Online analysis

and control

offline

online

Eigenvector matrix

Projection direction and classification

boundary

Model Para.


Case 2: Wide-area Close Loop Damping Control in China Southern Power Grid

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• The Chinese power grid includes about 30 provincial systems, and most of them are connected through 500kV AC lines.

• After region grids interconnection, the weakly damped low frequency oscillation becomes the bottleneck of improving system transfer capacity. Increasing the PSSs can not solve this problem substantially.

The oscillation lasted 3 minutes, and the amplitude reached

120MW. (China Southern Power Grid, 8.25.2008)

The oscillation lasted 5 minutes, and the amplitude reached 730MW. (Middle

China Power Grid, 10.29.2005)


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Mode 1

Mode 2

Key issues: 1. AC/DC interconnected system damping control strategies; 2. Wide-area controller structure design; 3. Multiple damping controllers coordination; 4. Time delay induced new oscillation modes analysis; 5. Wide-area random time delay adaptive compenstation.

GPS/Beidou


Close Loop Time Delay Distributions

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Mean value: 67.03ms

More than 98.7% is distributed in the range of 60~75ms.

The delay is mainly composed by phasor measurement and

calculation(≈30ms), signal transmission

(≈20ms) and calculation in the

main station (≈10ms).

• PMU—Control center —Control substation, transmission distance: >2000km

• Multiple 2M channels and UDP protocol were used to reduce delay.

Time Delay (ms)

Co

un

ts in 2

ho

urs


Time Delay induced New Oscillation Mode

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Frequency: 5~6Hz

Time delay: 50~60ms

Gain: K=5 Active

po

wer o

n th

e 5

00kV

line

(MW

)

Time (seconds)


RTDS Tests

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PMU cubicles

Control substation cubicles

Practical HVDC pole/station control/protection cubicles

Power Amplifi

er

RTDS（10 Racks）


Large Disturbances Field Tests Results

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• Disturbances: multiple HVDC monopole blocks (700MW), 500kV key inter-area tie-line tripping and closing;

• The damping ratio can be improved from 7.5% to 20.5%, and the transfer power limit can be enhanced more than 650MW.

5 6 7 8 9 10 11 12-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

时间（s）

贵州—云南相对功角（度）

高肇直流协调控制投入

高肇、兴安直流协调控制投入

协调控制退出

0 1 2 3 4 5 6 7 8 9 10-470

-460

-450

-440

-430

-420

-410

-400

时间（秒）梧罗线功率（

MW）

高肇调制控制单独投入

协调控制系统投入

协调控制系统退出

With WHDC

Without WHDC

Mode 1

Modes 1&2

Time (seconds)

Rela

tive a

ng

le b

etw

een

Yu

nan

an

d G

uizh

ou

Active

po

wer o

n th

e 5

00kV

line (M

W)


Our Group’s Roadmap Developing new EMS based on PMU/WAMS

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•PMU algorithm and device R&D

•WAMS framework design and system Implementation

•Wide-area damping control system

•Dominant load parameters identification ……

1993-2012

• Wide-area EMS framework design

• Power system state measurement

• New excitation and identification device

2013

• Multiple levels load identification

• Typical W-EMS application demonstration

• W-EMS experimental platform based on fast simulation

2014

•Complete W-EMS system implementation including dynamic power flow, important parameters or reduced-order system identification, steady and dynamic stability assessment and alarming, real time decision and close-loop control, all based on improved PMU/WAMS or AMI

2015-


New Thoughts from the Smart Grid Concepts

• Traditionally, the power balance is highly dependent on the spinning reserve, and the redundancy may cause huge wastes. If the information and demanding responses are fully invloved, the power system design and operation will be changed completely.

• The information can be delivered in nearly real time (ms), so the constraints about unobservability and uncontrollability can be relaxed, and then the conventional local or “trial-and-error” controllers can be all redesigned.

• In addition, with the employment of identification techniques, the problems of randomness and time-varying characteristics of some important power system parameters can be solved. The cost of increasing conservativeness for more reliability may be saved.

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清华大学

Thanks for your

attentions!


Future Trends about PMU/WAMS • Smart grid development will accelerate PMU/WAMS

applications;

• Dynamic state estimation based on more reliable and precise PMU/WAMS will be the foundation for new generation of EMS;

• Power system model and parameters can be identified and calibrated online in the near future;

• Innovative power system measurement, identification, analysis and control theory can be developed based on emerging information technologies applications.

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China-US S&T Strategic Policy Workshop on Smart Grid

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Transcript of China-US S&T Strategic Policy Workshop on Smart Grid