dr. u. kerin, siemens ag pmu-based wide area protection

© Siemens AG, EM SG PTI , 2015 All rights reserved www.siemens.com

PMU-based Wide Area Protection System – Concept and application in a large longitudinal system

Dr. U. Kerin, Siemens AG

EPCC 2015, Bled, Slovenia Dr. Uros Kerin © Siemens AG, EM SG PTI, 2015 All rights reserved. May 17-20, 2015

Why is there an increasing demand for information

on power system operations ?

• growing demand on electrical energy world wide

• more and more renewable sources with fluctuating infeed

characteristic

• change of the role of conventional plants

• part load and flexible operation of conventional plants

• high flexibility of transmission

• hybrid system to interconnect new renewable sources with

the grid

• operation closer to the stability and capacity limits of the

system

• new targets : sustainability, environmental friendly sources


Development over time

1960 1970 2000 2010

Passive electric systems (transformers, generators transmission lines, mechanical breakers) Passive electric systems (transformers, generators transmission lines, mechanical breakers)

Development of power systems

1980 1990

IGBT based FACTS, MT- HVDC

Complex intelligent systems power electronics, fast digital and protecition systems Complex intelligent systems power electronics, fast digital and protecition systems

Smart Grids

Distributed Generation

Electric Vehicles

First SCADA systems

Development of supervisory systems for power system control

PMU PMU

SCADA / EMS systems for power systems SCADA / EMS systems for power systems

Stability tools (DSA, TSA, VSA etc) Stability tools (DSA, TSA, VSA etc)

2020


The role of DSA (dynamic security assessment)

and WAPC (wide area protection and control)

Task of a modern DSA system:

• Monitor the actual system state

• Evaluate how critical a state is

• Recognize a trend of the system state’s development

• Select credible contingencies

• Pre-calculate and prepare which counter-measures should be started at

what time

DSA role is not to act as a fast control and protection system

A PMU-based wide area protection and control can take over this role:

• Automatic counteractions

• Lower risk of unsafe situations

• Minimization of outages and blackouts

• Control of congestion situations

• Avoiding of part system splitting

• Prevention of instability


PMU-based wide area monitoring and control -

a hybrid solution

SE: stored energy sources

LS: load shedding

RD: re-dispatch

RP: reactive power control

SR: spinning reserve

Stability

- voltage

- frequency

- generator

Reactive

Power Demand

Trend Analysis

Pattern Analysis

LS

RD

RP

Monitoring

Operator

Decision

Automated

Control

INDICES ANALYSIS CONTROL

SIGUARD DSA / SCADA

PMU

SE

SR

Dispatch Center

angle

voltage

frequency

loading

collapse


Use of WAPC as an intelligent, automatic WALS

(wide area load shedding)

fault location

identification

(fast)

load shedding (fast)

(where, how much)

actual load

flow situation

(slow)

PMU

SCADA, DSA

PMUs: information on fault type and location

SCADA + DSA: information on system state, LF situation and pre-calculated

counter measures


PMU indices – system state as a traffic light

Based on local information system state indices help to monitor the system

state and automatic counter-action


PMU indices to analyze system dynamic and stability

• Small signal stability index (SSSI)

• Angle index (AI)

• Frequency gradient index (FGI)

• Maximum Frequency Deviation Index (MFDI)

• Quasi-Stationary Voltage Index (QSVI)

• Voltage Drop Index (VDI)

• Voltage Ride Through Index (VRTI)

• Line Power Flow Index (LPFI)

• Transformer Power Flow Index (TPFI)

• Nodal Loading Index (NLI)


PMU indices

Example Voltage Ride Through Index (VRTI)

max

min 1,maxA

area j

area ji

t

area jadm

V dt

VRTI

time in ms3.0001.5007001500

100%

70%

45%

15%

lowest value of the

voltage band

highest value of the three line-to-line grid

voltage U/UN

limit line 1

limit line 2

range in which a disconnection

is only permissible by the

automatic system

selective disconnection of generators

depending on their condition

time when a fault occurs


PMU indices

Example Nodal loading Index (NLI)

Information about nodal system ranking margins are available in the LF data!

Vi

Yil

Yik

Yim

Vm

Vk

.

.

.

.

.

Pi, Qi

kik

N

iii ViiYYEEkk

/11

222 21/,4112

21iiiiiiiiii

iii PQP

Pe

ii

iiii

iiii

ii

ii

P

Q

iii

P

QEY

sincos

cossin2

1

Distance to loading limits:

4 1 / 1ii ii iand Q e

1,...min 1,max 4 ii

i NNLI

Information of neighboring admittances are necessary (SCADA/DSA)


Example of WALS

Large 500 kV system with longitudinal structure

Nord

Central

South

Case 1

Case 2


Blackout May, 22. 2013 in Vietnam

Blackout area

22 May 2013, 14:00

- High load situation 19.800

MW

- 1 major 500kV line lost

- About 9,4 GW, 22 provinces

and 8 millions customers lost

- 9 hours until system

restoration

Frequency dependent load

shedding too slow

Dynamic process

irreversable

Point of no return reached 1,5 sec


Case 1

Without LS (system separation)

With LS activated by WALS (stable system behavior)

• n-1 criteria violated

• Activation of 980 MW LS can avoid the black out

95 100 105 110 115 120 125-2000

-1000

0

Active power of transmission line

t [s]

P [

MW

]

95 100 105 110 115 120 125

49.8

50

Frequency

t [s]

f [H

z]

Nord

Central

South

95 100 105 110 115 120 1250

0.5

1

Faulted Bus Voltage

t [s]

U [

pu]

95 100 105 110 115 120 125

-40-20

020

Load Angle

t [s]Angle

[D

egre

e]

Nord

Central

South

95 100 105 110 115 120 125

-1000

-500

0


t [s]

P [M

W]

95 100 105 110 115 120 125

50

52

Frequency

t [s]

f [H

z]

Nord

Central

South

95 100 105 110 115 120 125

0

0.5

1

Faulted Bus Voltage

t [s]

U [p

u]

95 100 105 110 115 120 125-2

0

2x 10

4 Load Angle

t [s]

An

gle

[De

gre

e]

Nord

Central

South

95 100 105 110 115 120 125

-1000

-500

0


t [s]

P [M

W]

95 100 105 110 115 120 125

50

52

Frequency

t [s]

f [H

z]

Nord

Central

South

95 100 105 110 115 120 125

0

0.5

1

Faulted Bus Voltage

t [s]

U [p

u]

95 100 105 110 115 120 125-2

0

2x 10

4 Load Angle

t [s]

An

gle

[De

gre

e]

Nord

Central

South

95 100 105 110 115 120 125

-1000

-500

0


t [s]

P [M

W]

95 100 105 110 115 120 125

50

52

Frequency

t [s]

f [H

z]

Nord

Central

South

95 100 105 110 115 120 125

0

0.5

1

Faulted Bus Voltage

t [s]

U [p

u]

95 100 105 110 115 120 125-2

0

2x 10

4 Load Angle

t [s]

An

gle

[De

gre

e]

Nord

Central

South

95 100 105 110 115 120 125

-1000

-500

0


t [s]

P [M

W]

95 100 105 110 115 120 125

50

52

Frequency

t [s]

f [H

z]

Nord

Central

South

95 100 105 110 115 120 125

0

0.5

1

Faulted Bus Voltage

t [s]

U [p

u]

95 100 105 110 115 120 125-2

0

2x 10

4 Load Angle

t [s]

An

gle

[De

gre

e]

Nord

Central

South


Case 2

Without LS (no system separation)

With LS activated by WALS (stabilization of the system)

• Critical angle separation

• Stabilization of system frequency by LS of 1330 MW LS

95 100 105 110 115 120 125-1500-1000-500

0500


t [s]

P [

MW

]

95 100 105 110 115 120 12549

50

51

Frequency

t [s]

f [H

z]

Nord

Central

South

95 100 105 110 115 120 1250

0.5

1

Faulted Bus Voltage

t [s]

U [

pu]

95 100 105 110 115 120 125

-4000-2000

02000

Load Angle

t [s]Angle

[D

egre

e]

Nord

Central

South

95 100 105 110 115 120 125-1500-1000-500

0500


t [s]

P [

MW

]

95 100 105 110 115 120 12549

50

51

Frequency

t [s]

f [H

z]

Nord

Central

South

95 100 105 110 115 120 1250

0.5

1

Faulted Bus Voltage

t [s]

U [

pu]

95 100 105 110 115 120 125

-4000-2000

02000

Load Angle

t [s]Angle

[D

egre

e]

Nord

Central

South

95 100 105 110 115 120 125

-1000

-500

0


t [s]

P [

MW

]

95 100 105 110 115 120 125

49.5

50

Frequency

t [s]

f [H

z]

Nord

Central

South

95 100 105 110 115 120 1250

0.5

1

Faulted Bus Voltage

t [s]

U [

pu]

95 100 105 110 115 120 125-60-40-20

020

Load Angle

t [s]Angle

[D

egre

e]

Nord

Central

South

95 100 105 110 115 120 125

-1000

-500

0


t [s]

P [

MW

]

95 100 105 110 115 120 125

49.5

50

Frequency

t [s]

f [H

z]

Nord

Central

South

95 100 105 110 115 120 1250

0.5

1

Faulted Bus Voltage

t [s]

U [

pu]

95 100 105 110 115 120 125-60-40-20

020

Load Angle

t [s]Angle

[D

egre

e]

Nord

Central

South

95 100 105 110 115 120 125

-1000

-500

0


t [s]

P [

MW

]

95 100 105 110 115 120 125

49.5

50

Frequency

t [s]

f [H

z]

Nord

Central

South

95 100 105 110 115 120 1250

0.5

1

Faulted Bus Voltage

t [s]

U [

pu]

95 100 105 110 115 120 125-60-40-20

020

Load Angle

t [s]Angle

[D

egre

e]

Nord

Central

South


Conclusion

• Online tools in combination with WAPC based on PMU-measurement

can help to

• improve system operation

• increase use of system capacity

• make better use of system reserve

• create fast countermeasures in case of critical situations

• reduce risk of instability and black outs

• by automatic counteractions

• The example showed that the reliability of a non safe system can be

improved and system splitting and blackout can be prevented


Thank you for your attention

Dr. Uros Kerin

Consultant

Energy Management

Smart Grid Division

Siemens AG

EM SG PTI NC DYS

Freyeslebenstraße 1

91058 Erlangen

Germany

Phone: +49-9131-7-21023

Fax: +49-9131-7-35159

E-mail: [email protected]

www.siemens.com

dr. u. kerin, siemens ag pmu-based wide area protection

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