© ABB Group May 24, 2015 | Slide 1 Improving Power System Stability Through Integrated Power System...

© ABB Group April 18, 2023 | 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 GridTurbine and Generator Mechanics

Turbine driving torque Tm

Generator braking torque Te

Mechanical rotational speed ω

GeneratorTurbineω

Tm

Te


Model of a single Generator connected to GridTurbine and Generator Connection to Grid

Turbine + Generator

Generator breaker

Step-up transformer

Transmission line

Infinite bus (constant voltage)

GeneratorTurbine


Model of a single Generator connected to GridTurbine and Generator connected to Grid

GeneratorTurbine

A single generator connected to a large grid can be represented by the Phillips-Heffron model (assuming constant field voltage and mechanical torque)

K3s K3 T’do + 1

K2 K2K6 K5

K2

K4

K2

12H s

K2K1

2pi*fNs

∆Tm

∆Te

∆δ

∆Vg

∆E’q

∆ω


Model of a single Generator connected to GridLinearized 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)

K3s K3 T’do + 1

K2 K2K6 K5

K2

K4

K2

12H s

K2K1

2pi*fNs

∆Tm

∆Te

∆δ

∆Vg

∆E’q

∆ω


Model of a single Generator connected to GridTorque Disturbance Impact

Harmonic Phasor Representation

Torque equilibrium disturbance

Electric torque produces natural positive damping

K3s K3 T’do + 1

K2 K2K6 K5

K2

K4

K2

12H s

K2K1

2pi*fNs

∆Tm

∆Te

∆δ

∆Vg

∆E’q

∆ω

0°


Model of a single Generator connected to GridFast Voltage Control Impact

Harmonic Phasor Representation Generator plus AVR

Electric torque form AVR function produces negative damping torque

K3s K3 T’do + 1

K2 K2K6 K5

K2

K4

K2

12H s

K2K1

2pi*fNs

Kas Ka + 1

∆Tm

∆Te

∆δ

∆Vg

∆E’q

∆Vfd

∆ω


Model of a single Generator connected to GridPower System Stabilizer Function

Power System Stabilizer (PSS)

Band limited damping torque contribution

Speed estimator from electrical voltage and current signals

K3s K3 T’do + 1

K2 K2K6 K5

K2

K4

K2

12H s

K2K1

2pi*fNs

Kas Ka + 1

PSS

∆Tm

∆Te

∆δ∆ω

∆Vg

∆E’q

∆Vfd

∆Vgref


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)

GeneratorTurbine

AVRExcitation

Governor


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

GeneratorTurbine

AVRExcitation

Governor



SMTS-RT

GeneratorTurbine

AVRExcitation

Governor

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

K3s K3 T’do + 1

K2 K2K6 K5

K2

K4

K2

12H s

K2K1

2pi*fNs

Kas Ka + 1

PSS

∆Tm

∆Te

∆δ∆ω

∆Vg

∆E’q

∆Vfd

∆Vgref ∆Vgref = Vinjection

White noise

∆Te , ∆Pe



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 (green line) and without (blue line) the stabilizer connected:

( )( )

( )e

ref

P jF j

V j

-20

-15

-10

-5

0

5

10

15

20

25

Mag

nitu

de [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

with PSS, KS1=2

with PSS, KS1=3

with PSS, KS1=4

with PSS, KS1=10

© ABB Group May 24, 2015 | Slide 1 Improving Power System Stability Through Integrated Power System...

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Transcript of © ABB Group May 24, 2015 | Slide 1 Improving Power System Stability Through Integrated Power System...