Rudolf Wieser, Matthias Baechle, Valerijs Knazkins –ATPE...

© ABB Group January 4, 2015 | Slide 1

Improving Power System Stability Through Integrated Power System Stabilizers

Rudolf Wieser, Matthias Baechle, Valerijs Knazkins – ATPE


OUTLINE

Controlled Generator on Grid

� The main functions of an Automatic Voltage Regulator (AVR)

� The main functions of a

Power System Stabilizer (PSS)

How to test an AVR system

� Introduction to Real time Simulator

Grid Code compliance testing

� UNITROL built in compliance test functions


The main functions of an AVRAutomatic Voltage Regulator

State-of-the-art excitation systems are equipped with fast

acting voltage regulators:

� Advantages:

� Fast acting voltage control and reactive power

support

� Providing synchronizing torque component

� Disadvantage:

� Introducing negative damping torque component

� Solution to the reduced damping torque problem

� Power System Stabilizers


Model of a single Generator connected to Grid

Turbine and Generator Mechanics

� Turbine driving torque Tm

� Generator braking torque Te

� Mechanical rotational speed ω

GeneratorTurbine

ω

Tm

Te



Turbine and Generator Connection to Grid

� Turbine + Generator

� Generator breaker

� Step-up transformer

� Transmission line

� Infinite bus (constant voltage)



Turbine and Generator connected to Grid

� A single generator connected to a large grid can be

represented by the Phillips-Heffron model

(assuming constant field voltage and mechanical torque)



Linearized Model at certain Operating Point

� A single generator connected to a large grid can be

represented by the Phillips-Heffron model

(assuming constant field voltage and mechanical torque)



Torque Disturbance Impact

� Harmonic Phasor Representation

� Torque equilibrium disturbance

� Electric torque produces natural positive damping



Fast Voltage Control Impact

� Harmonic Phasor Representation Generator plus AVR

� Electric torque form AVR function produces negative damping torque



Power System Stabilizer Function

� Power System Stabilizer (PSS)

� Band limited damping torque contribution

� Speed estimator from electrical voltage and current signals


OUTLINE






� Introduction to Real Time Simulator




Synchronous Machine Transient Simulator Turbine, Generator, Transformer, Line to infinite Bus

� Typical turbine - generator arrangement in a power plant

� Automatic Voltage Regulator (AVR)


Synchronous Machine Transient Simulator Turbine, Generator, Transformer, Line to infinite Grid

SMTS-RT

� Real Time Simulation of

� Turbine and governor (simplified)

� Generator

� Breaker and step-up transformer

� Grid representation with infinite Bus Voltage



SMTS-RT

� AVR hardware

in the loop

Real Time Simulation



SMTS-RT 6000

UNITROL 6000


Synchronous Machine Transient Simulator SMTS-RT 6000; User Interface


OUTLINE






� Introduction to Real Time Simulator




AVR Grid Code ComplianceGrid Code Example

Excerpt from of a local grid code:

“Overall Excitation System Control Characteristic

�The frequency domain tuning of the Power System

Stabilizer shall also be demonstrated by injecting a

0.2Hz-2Hz band limited random noise signal into the Automatic Voltage Regulator reference� while the

Generating Unit is operating at a typical load level...

�The damping contribution of the Power System Stabilizer shall improve the system-stability within the

frequency-band of interest (compared to the system

response without a stabilizer):

i.e., 0.2Hz - 2Hz”


Grid Code Compliance Testing

Test scheme for

the measurement

of the

corresponding

transfer function



Time domain-

response of the

system without

the stabilizer,

while injecting

noise signals:

ExpertDays09



Time domain-

response of the

system with the

stabilizer, while

injecting noise

signals:

8%

ExpertDays09



Time domain-

response of the

system with the

stabilizer, while

injecting noise

signals:

ExpertDays09



Frequency domain

response of the

system with

(greenline) and

without (blue line)

the stabilizer

connected:

( )( )

( )

e

ref

P jF j

V j

ωω

ω

∆=∆

-20

-15

-10

-5

0

5

10

15

20

25

Magnitude [d

B]

�

Frequency [Hz]

10.2 5



Time domain

response of the

system with

(using different

gains) and

without (blue line)

the stabilizer

connected:

time [s]0 2 4 6 8

0.83

0.84

0.85

0.86

0.87P

e [p

.u.]

w /o PSS

w ith PSS, KS1=2

w ith PSS, KS1=3

w ith PSS, KS1=4

w ith PSS, KS1=10

Rudolf Wieser, Matthias Baechle, Valerijs Knazkins –ATPE...

Documents

Transcript of Rudolf Wieser, Matthias Baechle, Valerijs Knazkins –ATPE...