emtp modelling of control and power electronic devices for

EMTP Modellin g of Control andPower Electronic Devices for

Electric Power Quality AssessmentPh.D. Thesis

by

Benedito Donizeti Bonatto

Supervisor: Dr. Hermann W. Dommel

Co-Supervisor: Dr. William G. Dunford

[email protected] 2, 2001,Vancouver, B.C., Canada.

The University of British ColumbiaDepartment of Electrical and Computer Engineering

2356 Main Mall, V6T1Z4, Vancouver, B.C. Canada

Objectives of the project

To develop reasonably accurate models forcontrol and power electronic devices to evaluatetheir impact on the quality of power.

Models were developed for implementation in theElectromagnetic Transients Program (EMTP ), orin similar programs.

Outline of the presentation

Electric Power Quality and Power Electronics

Simultaneous Solution of Control and ElectricPower System Equations (SSCPS)

Power Electronics Modelling in EMTP-basedSimulations

Evaluation of the Impact of Power ElectronicDevices on the Quality of Power

Conclusions

Electric Power Quality and PowerElectronics: an Overview

Why is Power Quality Important?

– High costs ( $ ) related to the “poor” power quality.

– Electricity customers demand better quality on thepower.

– Increasing use of power electronic devices.– Increasing use of sensitive load equipment.

– Deregulation in the electricity industry , thus stimulatingcompetition.

– IEEE Standards

EMTP-type Simulation of Control Systems

Previous developments– TACS - Transient Analysis of Control Systems,

1977 (1 ∆t delay problem):

– MODELS, 1993.

– A. E. Araújo approach, 1993.

Elect r ic Network Solut ion( EMTP )

Cont ro l Sys tem Solut ion( TACS )

T ime De lay1 ∆t

the effect of a one time step (1 ∆t) delay inthe solution of EMTP-based simulation

0 10 20 30 40 50 60 70 80−8

−6

−4

−2

0

2

4

6

8

Time ( s )

Vo

ltag

e (

V )

vout

vin

Solution of a second order linear systemwith poles on the imaginary axis of the complex plane

1_ _ _ _ _

s-

+

1_ _ _ _ _

s

>9@

Y,1

Y287

the effect of a one time step (1 ∆t) delay inthe solution of EMTP-based simulation

0 10 20 30 40 50 60 70 80−8

−6

−4

−2

0

2

4

6

8

Time ( s )

Vo

ltag

e (

V )

vout

vin

Solution of a second order linear system with unstable oscillations caused by theintroduction of one time step delay

1_____

s-+

1_____

s

>9@

Y,1

Y287

delay1 ∆t

Simultaneous Solution of Control andElectric Power System Equations (SSCPS)

“Circuit approach” with the compensationmethod and Newton-Raphson iterativealgorithm for:– Current and Voltage Dependent Sources

– Transfer functions

– Limiters (hard and soft ; dynamic and static)

– Control Devices

Main advantage: “generality and flexibility”

Compensation Method

M-phase Thévenin equivalent circuit

vM

vs(M)

ZM

[ r T H E V ][ vO P E N ] [ i ]

vs(4)

Z4

vs(3)

Z3

vs(2)

Z2

vs(1)

Z1

[ v ]

... ...

...

v4 v3 v2 v1

i 1

i 2

i 3

i 4

i M

vO P E N _ MvO P E N _ 1

voltage and current sensors, control devices,function blocks and digital logic gates

– simultaneous solution with the compensationmethod using a Newton-Raphson iterativealgorithm, for any multi-terminal voltage-controlled voltage source

to sense voltage in a branch, just set the branch current

to zero, i.e., ij = 0 then define any linear or nonlinear voltage source

function at the controlled branch, i.e., vk= f( vj )

Newton-Raphson

Algorithm with

solution for limits

INPUT DATA

INIT IAL GUESSF O R C U R R E N T S

C A L C U L A T I O N O FB R A N C H V O L T A G E S[from Eq. (2.6) or (2.1)]

C A L C U L A T I O N O FRIGHT HAND S IDE

[negat ive valuesof Eq. (2.1)]

IS ITACCURATEENOUGH?

BUILD JACOBIAN MATRIX[part ial derivatives

of Eq. (2.1)]

S O L V E F O R C U R R E N T S

C H E C K F O R LIMITS

R E T U R N C U R R E N T S TO MAIN PROGRAM

IS THEREANY LIMIT

VIOLATION?Yes

Yes

U P D A T EC U R R E N T S

N o

SET VARIABLETO ITS LIMIT

MAX. NO. OFITERATIONS WAS

EXCEEDED?

N o

N o

Yes S T O P

Practical Applications

– Dependent Sources: Current-Controlled Voltage Source (CCVS)

Current-Controlled Current Source (CCCS)

Voltage-Controlled Voltage Source (VCVS)

Voltage-Controlled Current Source (VCCS)

– Independent Sources (connected between twoungrounded nodes)

– “Ideal” Operational amplifiers(ij=0 and vj=0)

– Ideal Transformers;

– Current and voltage sensors;

Transfer function implementation1 1

1 1 01 1

1 1 0

...( ) ( )( )

( ) ... ( )

0

m mm m

n nn n

n

b s b s b s bX s B sH s k k

U s a s a s a s a A s

n m a

−−

−−

+ + + += = = + + + +

≥ ≠

kb1_ _ _an

a1_ _ _an

1_ _ _

s

+

-

kb0_ _ _an

a0_ _ _an

1_ _ _

s

+

-

kbn_ _ _an

+

kbn-1_ _ _an

an-1_ _ _an

1_ _ _

s

+

-

+++

U ( s )

X ( s )

. . .

. . .

. . .

X ( s )U ( s )H ( s )

Transfer function implementation1 1

1 1 01 1

1 1 0

...( ) ( )( )

( ) ... ( )

0

m mm m

n nn n

n

b s b s b s bX s B sH s k k

U s a s a s a s a A s

n m a

−−

−−

+ + + += = = + + + +

≥ ≠

u ( t )

x ( t )

. . .

. . .

. . .

an___ M Ωkb0

an___ M Ωkb1

an_ _ _ M Ωkbn-1

an_ _ _ M Ωkbn

an_ ___ M Ω a0

an_ ___ M Ω a1

an_ ___ M Ω an -1

1 M Ω1 M Ω

1 M Ω1 M Ω

-1µ F-1µ F

-1µ F- 1 M Ω

X ( s )U ( s )H ( s )

Example: First Order Transfer Function

X ( s )U ( s )1 0

_ _ _ _ _ _ _ _ _ _

0.01 s + 1

kb0_ _ _a1

a0_ _ _a1

1_ _ _

s

+

-

U ( s )

X ( s )

u ( t )

x ( t )

a1___ M Ωkb0

a1_ ___ M Ω a0

- 1µ Fu ( t ) x ( t )1 k Ω

- 10 k Ω

- 1µ F

=

basic control blocks, transfer functions andfilters

Classical linearized “swing equation” used in power system small signal stability studies of a single machine connected to an infinite bus

K S

K D

ω0_____

s

1_____2H s

-

-

+ ∆δ∆ωU

∆Tes

∆Ted

∆7D∆T m

SX

. ωn2

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _s2 + 2 ξωn s + ωn

2

∆δ∆7P

SX


Simulation results of the synchronous machine rotor angle deviation,in the presence of a positive damping torque coefficient

0 1 2 3 4 5 6 7 8 9 10−0.25

−0.2

−0.15

−0.1

−0.05

0

0.05

0.1

Time ( s )

Va

ria

ble

s in

pe

r u

nit

( p

.u. )

∆

5*

Tes

Ted

Ta

∆ω

Tm

∆δ

∆

∆

∆


Simulation results of the synchronous machine rotor angle deviation,in the presence of a negative damping torque coefficient

0 1 2 3 4 5 6 7 8 9 10−150

−100

−50

0

50

100

150

200

Time ( s )

Ro

tor

an

gle

de

via

tion

( p

.u. )

∆δ

Power Electronics Modelling in EMTP-based Simulations

Development of subroutine GATE– allows in MicroTran the dynamic firing control

of simplified models for thyristors, GTO’sIGBT’s, represented as EMTP-based voltage-controlled switches

Development of a “simultaneous” solutionfor voltage-controlled switches

Implementation of nonlinear diode model inEMTP-based programs

Evaluation of the Impact of PowerElectronic Devices on the Quality of Power

Dynamic interaction between powerelectronic devices and power systems

Power quality assessment through EMTP-based programs

EMTP-based simulation cases with SSCPS -Simultaneous Solution of Control and ElectricPower System Equations

Dynamic interaction between powerelectronic devices and power systemsdepends on:

– type of “front-end” electronic converter

– number of phases and converter pulseconfiguration

– short-circuit power and voltage level– point of connection in the network

– power and number of power electronic loads

– design and control of the electronic converter

Power quality assessment through EMTP-based programs

induction furnace

harmonic study

138 kV

Bus , - 13.8kV Bus I I - 13.8kV

InductionFurnaces

HarmonicPassive Filters

PCC

477.0 ACSR - 2km

25 /30MVA138/13.8kV

9.72% (25MVA)

25 /30MVA138/13.8kV

10.2% (25MVA)

Ssc 3ph = 2,881.3 / -78.0 o MVASsc 1phg = 1,734.1 / -77.4 o MVA

9.0MVAr13.8kV

3 .0MVA13.8/0.48kV

5.9%

336.4 ACSR - 0 .5km

0.48kV

dynamic control of the firing angles of athree-phase six-pulse thyristor bridge rectifier

G 1

2 Ω

i L O A D

Vm a x = 81.65 [V]

f = 60 [Hz] vL O A D

vS Y N C H R

vA

400 µ )

vD C

5 P+ +

-

vB

vC

PI A C O S

G 1G 2G 3G 4G 5G 6

G 3 G 5

G 4 G 6G 2

vA L P H A

vE N A B L E /

D I S A B L E

vL I MvPIvE R RvR E F

vS E N S = vL O A D

-

+

100 [V ]

1 [V ]

K P=0.01K I= 1.0

1

-1

vA C


0 5 10 15 20 25−150

−100

−50

0

50

100

150

Time ( ms )

Vo

ltag

e (

V )

C

urr

en

t (

A )

iLOAD

vsynchr

vLOAD

vDC

vA


0 5 10 15 20 25 30 35 40 45 50−20

0

20

40

60

80

100

120

Time ( ms )

Vo

ltag

e (

V )

C

urr

en

t (

A )

vALPHA

vREF

vERR

vSENS

=VLOAD


0 5 10 15 20 25 30 35 40 45 500

0.2

0.4

0.6

0.8

1

1.2

1.4

Time ( ms )

Vo

ltag

e (

V )

C

urr

en

t (

A )

vLIM

vPI

dynamic control of a three-phase PWMvoltage source inverter (VSI)

I G B T1 I G B T3 I G B T5

I G B T4 I G B T6 I G B T2

vTRI

vA

vB

vC

vS A

vS B

vS C

vNEUTRi S A - N E U T R

i S B - N E U T R

i S C - N E U T R

0.8 [V]

0.8 [V]

0.8 [V]

1 [V]

10 9 Ω

3.87 Ω 7.7 P+

450 [V]

f = 60 [Hz]

f = 1500 [Hz]phase = -180 [degrees]

C O M P A R A T O R

N O T

dynamic control of a three-phase PWMvoltage source inverter

0 5 10 15 20 25−1.5

−1

−0.5

0

0.5

1

1.5

Time ( ms )

Vo

ltag

e (

V )

C

urr

en

t (

A )

vA v

TRI


0 5 10 15 20 25−600

−400

−200

0

200

400

600

Time ( ms )

Vo

ltag

e (

V )

C

urr

en

t (

A )

vSA


0 5 10 15 20 25−600

−400

−200

0

200

400

600

Time ( ms )

Vo

ltag

e (

V )

C

urr

en

t (

A )v

SA − v

NEUTR

5 * iSA−NEUTR


0 5 10 15 20 25−60

−40

−20

0

20

40

60

Time ( ms )

Vo

ltag

e (

V )

C

urr

en

t (

A )

iSA−NEUTR

iSB−NEUTR

iSC−NEUTR


0 5 10 15 20 25−600

−400

−200

0

200

400

600

Time ( ms )

Vo

ltag

e (

V )

vSA

− vSB

Main Contributions

development of a “simultaneous solution for linearand nonlinear control and power systemequations” (SSCPS) in EMTP-based programs(with NO time step delay as the existing in TACSsince 1977). A “circuit approach” was proposed inthis thesis;

Main Contributions

experimental implementation in MicroTran (theUBC version of the EMTP), based on SSCPS, of asimultaneous solution for:

9 linear and nonlinear current and voltage dependentsources ; transfer functions; hard and soft limiters;mathematical and transcendental FORTRANfunctions; special control devices; transformation ofvariables; voltage-controlled switches

9 nonlinear model of a diode semiconductor

Main Contributions

development of the subroutine “GATE” inMicroTran, allowing the dynamic control of theturn-on and turn-off times of semiconductor devices

development of power electronics simulation casesin MicroTran, with SSCPS and GATE

Recommendations for future work

automatic calculation of initial conditions

frequency response of integrated control andpower system equations

detailed nonlinear models of semiconductor devices

generic nonlinear dependent sources

voltage and frequency dependent aggregated loadmodels

models for FACTS and Custom Power devices

Conclusions

New EMTP models for control and powerelectronic devices for electric power qualityassessment were developed in this Ph.D. thesisproject.

EMTP simulations offer theoretical and practicalinsights into the evaluation of power quality, both bytime-domain simulation techniques and byfrequency-domain simulation techniques.

The technical impact of power electronic deviceson the quality of power can be evaluated with themodels developed in this work.

emtp modelling of control and power electronic devices for

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