UNITROL Real-time generator model Demo

© ABB Group May 3, 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




How to test an AVR system 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




How to test an AVR system 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 jV 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


UNITROL Real-time generator model Demo

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