UCI Power Electronics Lab One-Cycle Control and Its ...medinid/energy-gordon/Smedley/First day/israel...One-Cycle Control and Its Applications in Distributed Generation Keyue Smedley

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UCI Power Electronics Lab

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One-Cycle Control and Its Applicationsin Distributed Generation

Keyue Smedley

Dept. of Electrical Eng. and Computer Science

University of California,

Irvine, CA 92697, USA

[email protected]

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Table of Contents

I. Our Power Systems• It is time for renovation

• Power electronics is a key Component

II. One-Cycle Control• A PWM Computer

• Active power filter derivation

• Universal OCC Controller

III. Utility Applications• Examples

• A possible configuration

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I. Our Power System

One of the largest structural achievement by humans.

Thousands ofgenerating stations,tens of thousandsof transmissionand distributionsubstations, 150control areaoperators, and over200,000 miles oftransmission lines.

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For every BTU electricity generated, twice of that amount is lost, which wastes the natural resources and creates environmental pollution. Courtesy of Energy Information Administration Annual review3,333 BTU=1 kwh, 900million tons of coal/year

2001 Electricity flow in US (Quadrillion BTU)

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Issues in our current power system

Centralized generation: =>efficiency~30%=>consumes large amount of fossil fuel~70%=>environmental impact

Long transmission line: =>transmission losses=>system oscillation

Load harmonic currents: =>transformer heating=>reduced system capacity

Large system: =>venerable to cascading faults

Grid

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Power Electronics is a key element fordistributed generation

• Inverters --- renewable and alternative energy power generation• PFC rectifiers--sinusoidal current use• APF--- power quality control• STATCON --- VAR compensation and voltage support

Inverter

APF

PFC

TurbineConverter

Converter

Statcon

Fuelcell

RegenerativeFuelcell

Inverter

Reversableinverter

Central plant

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• Cycle by cycle control =>fast andprecise transient

When 1/Ts ∫0t V2dt=V1t=dTs

V2d=V1

• OCC solves the first orderpolynomial equation

• Most power electronics problemscan be expressed by a first orderpolynomial equation.

CLK

v (t)+

v (t)1

Q

II. One Cycle Control

Comparator

Integrator

Q Q

S R

clock

d

v1 v2

reset

with reset

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OCC--A PWM Computer

+

_R

S

Q

Q

ClockGenerator

CMP

FFI

R

OIntegratorw/ reset

I

R

OIntegratorw/ reset

+

+

+

+

v 1 v 2 v 3

...... 2I

R

OIntegratorw/ reset

+

+

v 4

3 v (t)+

€

v1 = v2d + v3d2 + v4d

3 + ⋅ ⋅ ⋅

OCC solves nth order polynomial equations

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av

bv

cv

aL

cL

bL

anD

bnD

cnD

apD

bpD

cpD

apS

bpS

cpS

anS

bnS

cnS

P

N

E

Three-phase nonlinear load

0 60 120 180 240 300 3601

0

θ

av bv cv

The line cycle is divided intosix regions

€

vavc

= Re ⋅

iaic

€

Vm ⋅1− dan1− dcn

= Rs ⋅

2 11 2

⋅iaic

dbn =1

€

Vm =E ⋅RsRe

Control goal:

Control key equation 0-60°:

Three-Phase Converter Control--e.g. active power filter derivation

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Three-Phase Converter

+ +Current selectioncircuit

Region se lection circuit

Driv

e si

gnal

dist

r ibu t

or

Sap Sbp Scp

San Sbn Scn

P

N

Vdc sensor

LaLbLc

Vdc

C

va,b,c ia,b,c

Va Vb Vc

Reset

-+

Vref+ _

2

2

+ +

S Q

R Q

S Q

R Q

+-

+-

PID

+

+

+One-cyclecontrol core

ip

in

a b c

toSapSanSbpSbnScpScn

+

++

+

iaref

ibref

icref

RsiaRsibRsic

Simple,Reliable,Robust,Modular,Universal.

For symmetricor asymmetricsystems.

No multiplier, No DQ conversion,No software in the loop.

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A Universal 3-phase Controller

OCC controlleris universal!

InverterRectifierAPFSTATCONEtc.

One controller does all!

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III. OCC ApplicationsP

N



Driv

e si

gnal

d is t

r i but

o r

Vdc sensor

va,b,c ia,b,c

Reset

-+

Vref+ _

2

2

+ +S Q

R Q

S Q

R Q

+-

+-

PID

+

+


ip

in


+

RsiaRsibRsic

Sap Sbp Scp

San Sbn Scn

LaLbLc

Vdc

C

Va Vb Vc

Load



Driv

e si

gnal

d is t

ribut

or

Sap Sbp Scp

San Sbn Scn

P

N

Vdc sensor

LaLbLc

Vdc

C

va,b,c ia,b,c

Va Vb Vc

Reset

-+

Vref+ _

2

2

+ +

S Q

R Q

S Q

R Q

+-

+-

PID

+

+


ip

in

a b c


+

RsiaRsibRsic

Nonlinear load

icom

iload

P

N



Driv

e si

gna l

dis t

ri but

o r

Vdc sensor

va,b,c ia,b,c

Reset

-+

Vref+ _

2

2

+ +

S Q

R Q

S Q

R Q

+-

+-

PID

+

+


ip

in


+

Sap Sbp Scp

San Sbn Scn

LaLbLc

Vdc

C

Va Vb Vc

++

+

kva

kvb

kvc

RsiaRsibRsic

dc source

Iref :



Driv

e si

gnal

dis t

r ibu t

o r

Sap Sbp Scp

San Sbn Scn

P

N

Vdc sensor

LaLbLc

Vdc

C

va,b,c ia,b,c

Va Vb Vc

Reset

-+

Vref+ _

2

2

+ +

S Q

R Q

S Q

R Q

+-

+-

PID

++

+ +

+


ip

in

a b c

kva

kvb

kvc


+

RsiaRsibRsic

Nonlinear load

€

e jθ

€

e jθ

€

e jθ

icom

iload

Iref :

PFC

GCI

APF

SVC

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Active Power Filters

transformersubstation

Grid

Inductive load

Capacitive load

APF

• APF actively cancels the harmonics from the load• The line current is sinusoidal• APF only processes the harmonic and reactive power• Can be used in equipment, buildings, substations, etc

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Experimental Waveforms

Phase A line voltage Three-phase currentsTHD=3.2%PF~1

Phase A line voltagePhase A line currentPhase A APF current Phase A load current

Symmetric operation:

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Start Point

Start Point

Grid Voltage

APF CurrentStart PointGrid Current

Grid Voltage

Start Point

Start-up Transient Test

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Load Step Up Transient Test

Load current-->

APF current -->

<--Line current

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Grid connected Inverter for Power Generation

•Sinusoidal current injection•Robust performance•Maximum power point tracking

Renewable/Alternative Power Generation

OCCGrid-tiedinverter

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Traditional rectifiers draw harmonic current

One-cycle control rectifiers draw sinusoidal current

One-cycle Control Rectifiers for Harmonic Suppression

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Static Synchronous Compensator

1. Superior voltage supporting capability2. Uses small dc capacitors instead of large dc capacitors3. Needs smaller space than conventional switched capacitors.

OCC-STATCOM for Reactive Power Compensation

OCC STATCOM

VAR

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One of Possible Hybrid Configuration

OCC Converter functions as:inverterrectifieractive power filtervar generator

nonlinear load

fuel cell unit

fuel cell unit

micro turbine

OCC converter

micro turbine

nonlinear load

nonlinear load

nonlinear load

Grid

Local area

OCCconverter

reversablefuel cell

OCCconverter

solar cells

OCCconverter

wind turbine

OCCconverter

P Q H

P

P P P

P Q H

smedley-occ-dg

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OCC Unified Power Quality Conditioner

AF1 (Series AF) AF2 (shunt AF)Source voltage

harmonicssuppression

Load currentharmonics

compensationSource voltage

RegulationLoad reactive Current

compensation

Voltage balancing Unbalanced Loadoperation

Voltage flick/sag/dipcompensation

Neutral-line/ commonmode currentcancellation

DC Voltage regulation

EnergyQualityItems

Impulse & EMI suppression

• Improve voltage quality.• Improve current quality.• Improve power system stability.• Improve power system security.• Improve transmission efficiency

OCC UPFC

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Phase-A Voltage

Load current: THD ≈ 25%Cos _ ≈0.76, PF ≈ 0.74

Line Current: THD ≈ 7%Cos _ ≈ 1, PF ≈ 1

Phase-A Voltage

Voltage unbalanceand harmoniccompensation==>

<==Reactive and nonlinear Load current compensation

OCC-UPQCBefore After

Before After

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Reversible OCC Rectifier


occ rectifierdc output Motor load,

battery, orreversable fuelcells

Grid

line current THD<0.5%PF~1.

Regenerative power generationEnergy conservation

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APF-Inverter in One


Grid


OCC GCIwith MPPTPhoto voltaic

Nonlinear loadsTHD>30%

DC

MPPT at DC side Cancel harmonics at ac side

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Frequency Converter


Grid

OCC converterOCC converter

variable frequency accurrent THD<0.5%PF~1.


Windpower

Two OCC converters back to back to Form high power quality frequency converter.

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APF-STATCON in One


Grid

Inductive load

Capacitive load

OCC STATCON

line current THD<0.5%VAR adjustable

Generate reactive as needCancels the harmonics in the line.

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OCC APF for Mega Power


Grid

thyristor inverterdiode rectifier

variable frequency accurrent THD<0.5%PF~1.

OCC APFOCC APF


Windpower

Combine with Diode/Thyristor type of convertersTo achieve high power and low THD.

1MVA

150KVA 150KVA

Documents

UCI Power Electronics Lab One-Cycle Control and Its ...medinid/energy-gordon/Smedley/First day/israel...One-Cycle Control and Its Applications in Distributed Generation Keyue Smedley