Presentation - Power Electronics Arrangements in Distributed Systems

8/14/2019 Presentation - Power Electronics Arrangements in Distributed Systems

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UNIVERSITY OF ZIELONA GORA

INSTITUTE OF ELECTRICAL ENGINEERING

POWER ELECTRONICS ARRANGEMENTS

IN DISTRIBUTED SYSTEMS


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DISTRIBUTED GENERATION: WHAT IS IT?

Distributed Resources (DR) are small (usually under 10 MW),

modular electric generation and storage technologies that

provide electric capacity and/or energy when and where

needed. DR may either be interconnected with the electric grid

or isolated from the grid in "stand-alone" applications, but itslocational value is important to its economics and operation.

Distributed generation = DGDistributed storage = DS


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Today's Central Utility Tomorrow's Distributed Utility?

Central Generation

Customers

CustomerEfficiency

RemoteLoads

Wind

PV

Genset

Fuel Cell

Battery

Central Generation

Microturbine

DISTRIBUTED GENERATION: WHAT IS IT?


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Mass produced

Modular

Small (


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Economic advantages included one or more of the

following:

Load management

Reliability

Power quality Fuel flexibility

Cogeneration

Increased distribution grid reliability/stability

ECONOMIC ADVANTAGE FROM DG SYSTEMS


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IC Engines SmallTurbines

Micro-turbines

Fuel Cell

CommercialAvailability

Wellestablished

Wellestablished

Newindustry

Wellestablished

Size 50 kW-5 MW

1 MW 50 MW

25 kW 75 kW

1 kW 200 kW

InstalledCost ($/kW)

$800 $1500

$700 $900

$500 $1300

$3000

O&M Costs(cents/kWh)

0.7 1.5 0.2 0.8 0.2 1.0 0.3 1.5

Fuel Type Diesel,propane,NG, oil &biogas

Propane,NG,distillate oil& biogas

Propane,NG,distillate &biogas

Hydrogen,biogas &propane

Commercial Status of DG


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Photovoltaicgeneration

Fuel cells

DC-to-ACConversion

Variable-speedwind generator

FrequencyConversion

Smallhydrogenerator

AC Lines(usually isolatedfrom utility lines)

DC AC

Variablefrequency

Fixedfrequency

* kW ~ * MW

POWER ELECTRONICS IN DISTRIBUTED GENERATION


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ENERGY STORAGE

AC/DC

Conversion

Superconductingmagnet energy

storage

LargeCapacitors

AC UtilityLines

DC

AC

* kW ~ * MW

Batteries

DISTRIBUTION: Custom Power

Power electronicsConverters/Controllers

SwitchingEquipments

Automatedprocessing/

manufacturing

customers

Low-qualitypower

High-qualitypower

*0 kW ~ *0 MW

POWER ELECTRONICS IN


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Advanced Solutions

Transmission

Link

Enhanced

Power Transfer

and Stability

Line

Reconfiguration

Fixed

Compensation

FACTS

Energy Storage

BetterProtection

Increased

Inertia

BreakingResistors Load

Shedding

FACTS

Devices

Traditional Solutions

SVC

STATCOM

TCSC, SSSC

UPFC, IPFC,

Steady State

Issues

Voltage Limits

Thermal Limits

Stability Limits

Dynamic

Issues

Transient Stability

Damping Power Swings

Post-Contingency

Voltage Control

Voltage Stability

FACTS - APPLICATIONS AND IMPLEMENTATIONS


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A transmission system can carry power up to its thermal loading limits. But ipractice the system has the following constraints:

-Transmission stability limits

-Voltage limits

Transmission stability limits: limits of transmittable power with which

transmission system can ride through major faults in the system with its powe

transmission capability intact.

Voltage limits: limits of power transmission where the system voltage can b

kept within permitted deviations from nominal. Voltage is governed b

reactive power (Q). Q in its turn depends of the physical length of thtransmission circuit as well as from the flow of active power. The longer th

line and/or the heavier the flow of active power, the stronger will be the flow o

reactive power, as a consequence of which the voltage will drop, until, at som

critical level, the voltage collapses altogether.

FACTS - THE CONCEPT


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FACTS offers ways of attaining an increase of power transmission capacity at

optimum conditions, i.e. at maximum availability, minimum transmission

losses, and minimum environmental impact. Plus, of course, at minimuminvestment cost and time expenditure.

The term FACTS covers several power electronics based systems used for

AC power transmission. Given the nature of power electronics equipment,

FACTS solutions will be particularly justifiable in applications requiring one

or more of the following qualities:

-Rapid dynamic response

-Ability for frequent variations in output

-Smoothly adjustable output.

FACTS - THE CONCEPT


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CONTROLLABLE PARAMETERS

Control of the line impedance X : thyristor-controlled series capacitor

Provides a powerful means of current control

When the angle is not large, substantially provides the control of active power

Control of angle: phase angle regulator

Provides a powerful means of current control Provides active power flow when the angle is not large

Series voltage injection: perpendicular to current

Controls the magnitude of current

Injects reactive power: static synchronous series compensation Provide a powerful means of controlling the active power

Parallel voltage injection: arbitrary phase

Controls the magnitude and the phase of the current.

Provides a powerful means of controlling the active and reactive power flow. Requires injection of both active and reactive power in series.

Line voltage regulation: thyristor-controlled voltage regulator

Very cost-effective means for reactive power flow control

X control (series C) + voltage regulation (shunt C) can also provide a cost-

effective means to control both the active and reactive power flow.


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E1

E2

I

X

E1 - E2

Injected Voltage

Injecting Voltage in series with the line mostly change real power

E1 / 1 E2 / 2I

P&Q

Vin

P1 = E1 . E2 . sin () / (X - Vin / I)

VOLTAGE-SERIES INJECTION


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E2 / 2

P1 = E1 (E2 . sin ())/X

X

I

E1

E2

E1 - E2

Regulating end bus voltage mostly change

reactive power.

E1 / 1I

P&Q

Q / V

VOLTAGE - PARALLEL CONTROL


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X

E1 / 1 E2 / 2I

P&Q

Changes in X will increase or decrease real power flow for a fixed angle or

change angle for a fixed power flow. Alternatively, the reactive power flow

will change with the change of X. Adjustments on the bus voltage have

little impact on the real power flow.

Vs

I

Xeff = X - Xc

Vx

Vr

Vc

Vseff = Vs + Vc

Vx

I

Vxo Vr

Vc

VseffVs

SERIES COMPENSATION


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X

E1 / 1 E2 / 2

I

P&Q

P

E1

E2

I

E1 - E2

Injected Voltage

Integrated voltage series injection and bus voltageregulation (unified) will directly increase or decrease real

and reactive power flow.

SERIES AND PARALLEL COMPENSATION


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SERIES AND PARALLEL COMPENSATION

System bus

C+

Vdc

s

Parallel Compensation

System busV

Transformer leakage

inductance

Transformer

o

X

Converter

SwitchingDC-AC

V

I

Coupling

C+

Vdc

s

Converter

SwitchingDC-AC

Transformer leakage

inductance

TransformerCoupling

Series Compensation

o

XV

I

VV

MULTILEVEL INVERTERS


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MULTILEVEL INVERTERS


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Parallel Connected:

Parallel Active Power Filters (Parallel APF)

Static VAR Compensator (SVC)

Static Synchronous Compensator (STATCOM)Battery Energy Storage System (BESS)

Combined Series and Series-Parallel Connected:

Series Active Power filter (Series APF)Static Synchronous Series Controllers (SSSC)

Thyristor Controlled Series Capacitor (TCSC)

Unified Power Flow Controller (UPFC)

Unified Power Quality Conditioner (UPQC)

Universal Power Line Conditioner (UPLC)

Interline Power Flow Controller (IPFC)

FACTS DEVICES


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Parallel Active Power Filters (Parallel APF)Static Synchronous Compensator (STATCOM)

Parallel-connected static var compensator

Capacitive or inductive output current controlled independently of the acsystem voltage

Static Var Compensator (SVC)

Parallel-connected static var generator or absorber

Output is adjusted to exchange capacitive or inductive current

Maintain or control specific parameters of the electrical power system

(typically bus voltage).

Thyristor-based Controllers

Lower cost alternative to STATCOM

Battery Energy Storage System (BESS)

PARALLEL FACTS

PARALLEL APF


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PWM CONTROL

V I

L

C

ISi

i*c

ic

Reactive power

compensation Source currents higher

harmonics compensation

DC element voltage contr

MAJOR TASKS:

PARALLEL APF

PARALLEL APF STRUCTURE


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S1 S3

S4 S6

C

Control

L

+

-

ii

i

ca

cb

cc*

*

*

i

C

R

iii

fa

fb

fc

S5

S2

S1 S3

S4 S6

Control

L

iii

fafb

fc

S5

S2

i

i

icacb

cc

*

*

*

CR

iii

ca

cb

cc

VSI

CSI

PARALLEL APF - STRUCTURE

MODULAR ACTIVE POWER FILTER MAPF


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LOADSiL

APF-2

iS=iL-iFA3

iFA

APF-1

APF-K

MODULAR ACTIVE POWER FILTER - MAPF

MAPF EXPERIMENTAL RESULTS


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OFF

SYMMETRIC LOAD

ON

ASYMMETRIC LOAD




25/50


IL

SVC


26/50

SVC

TThyristor

CControlled

RReactor

TThyristor

SSwitched

CCapacitor

SStatic VVar CCompensator


27/50

SERIES CONTROLLERS


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Series Active Power filter (Series APF)Static Synchronous Series Compensator (SSSC)

A static synchronous generator without an external electric energy

source

Output voltages in quadrature with, and controllable independently of,

the line current

Control over the overall reactive voltage drop across the line, and

thereby the transmitted electric power.

May include transiently rated energy storage to enhance the dynamic

behavior of the power system by additional temporary real power

compensation, to increase or decrease momentarily, the overall real(resistive) voltage drop across the line.

Thyristor Controlled Series Capacitor (TCSC)

Smooth control of series capacitive reactance

SERIES CONTROLLERS

SERIES APF


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Voltage harmonics

compensation Stability improvement

Current harmonics blockin

MAJOR TASKS:

Control PW M

L

VC

is

V

V*c

C

VS

iS

V

VV VC

VTV

V c

S

v + vF h

VXL

X LI + IF h

ST

SERIES APF - STRUCTURE


30/50

S1 S3

S4 S6

C1

Control

L

-

V

V

ca

cb

cc**

*

V

C

R

V

VV

fa

fb

fc

S5

S2 C2

C

+

Vca

V a Vsa

i sa

SERIES APF STRUCTURE

SSSC


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X

E1 / 1 E2 / 2I

P&Q

P1 = E1 (E2 . sin ()) / Xeff

Xeff = X - Vinj/I

SSSC

TCSC


32/50

Line Impedance Compensation

Can Control Power Flow Continuously

E1 / 1 E2 / 2P&Q

P1 = E1 (E2 . sin ()) / Xeff

X

Xeff = X- Xc

TCSC

COMBINED CONTROLLERS


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A combination of STATCOM and SSSC coupled via a common dc

link

Bi-directional flow of real power between the SSSC and theSTATCOM

Concurrent real and reactive series line compensation without an

external electric energy source.

The real and reactive power flow control in the line.

Independently controllable shunt reactive compensation.

Additional external storage: more effective in control of system

dynamics

Unified Power Quality Conditioner (UPQC)

Universal Power Line Conditioner (UPLC)

Interline Power Flow Controller (IPFC)

UPFC


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X

E1 / 1 E2 / 2I

P&Q

Regulating Bus Voltage and Injecting Voltage In

Series With the Line Can Control Power Flow

UUnifiedPPower

FFlow

CController

SStaticSSynchronous

SSeries

CCompensator

SSTTAACC

OOMM

P1 = E1 (E2 . sin ()) / XeffXeff = X - Vinj / I

1 = E1(E2 - E2 . cos ()) / X

UPQC


35/50

L

V

C

Control Control

UPQC

Control

I*CV*C

V

iS

iS

Vf

if

i

iC

Vc

L

MAJOR TASKS:

Source current harmonics

compensationSystem stability improvement

Reactive power compensation

DC element voltage control

Voltage controlVoltage harmonics

compensation

iV Vs

is

Ha rm onicssens ib le load

V s

i c

i

V

i s

V c

U P Q C

UPQC - STRUCTURE


36/50

S1 S3

S4 S6

S5

S2

S7 S9

S10 S12

Vca

V a Vsa

UPQC controlVoltage cntrol Current control

i

i

ca

cb

cc*

*

*

iV

V

ca

cb

cc*

*

*

V

+

+

S11

S8

V fa

V fb

V fc

i fa

Lf

C f

R f

i ca

i co

i so

i sc

i sb

i sa i a

i b

i c

i o

Non-linearload

Linear load

Unbalanced netwith harmonicsi

R sC s

C1

C2

UPLC - STRUCTURE


37/50

LC

Current

cntrol

Voltage

control

UPLC control

V*Ci*C

V

i h

iS

if

i f

L

V

i

ih

VS

is

i c

VC

UPLC =UPFC + UPQC

C

i hVc

L 2

G2

G1

L 1

i c

i s

Vs

V

V

Vsis

VS

V

Vc

i

UPLC VOLTAGE REGULATION


38/50

V

i

G1

G1

L1

VL1

V i

.

.

i (q0)

VL1

VL1

VG1

VG1

V

V

V:

V:

vqi

vqi

)0(

)0(

UPLC POWER FLOW CONTROL


39/50

VG2VsVc

i s

V

L2

Ps G2

VL2

VG2

VL2

Vs

V

(q0)s

VG2

VL2

V

(p>0)VG

.

.

Vs

is

VG2

VL2V

(p


40/50

E1 / 1 E3 / 3

E2 / 2

IPFC PRINCIPLE OF OPERATION


41/50

INVERTER

11Vr

1CVr

1XVr

1Ir 21V

r

1X

12V

r

2CV

r

2X

Vr

2Ir 22V

r

2XDC

LINK

INVERTER

SYSTEM 1

SYSTEM 2

Active power transmitted to the receiving-end bus:

( )444 3444 21444 3444 21

44444 344444 21

11

1

121

1

121

121

1

121

sin

21111121

1

1121

21 cossinsincossincossincos

cpcq V

c

c

V

c

c

X

VV

X

VV

X

VVP

+++=

Reactive power transmitted to the receiving-end bus:

( )444 3444 21444 3444 21

44444 344444 21

11

1

121

1

121

121

1

121

1

2

21

cos

11211121

1

112121 sininscoscossinsincoscos

cqcp V

c

c

V

c

c

X

VV

X

VV

X

V

X

VVQ

+=

IPFC PRINCIPLE OF OPERATION


42/50

11Vr

1CVr

1XV

1Ir 21V

r

1X

12V

r

2CV

r

2XVr

2I

r22V

r

2X

1nVr

INVERTER

DC

LINK

INVERTER

INVERTER

r

SYSTEM 1

SYSTEM 2

SYSTEM n

Parallel inverters power rating:

====

n

1i

max*i2

maximax

i2

mini1n

1i

maxIPFCiParallel Pcos

V

V1PP

IPFC RESULTS OF SIMULATIONS


43/50

2 4 6 8 10

80

70

60

50

40

30

20

case a

Number of Systems

Savin

gsoftheparallelinverterspowerrating

case b

Savings of the parallel inverter's power rating

for given number of Systems.

FACTS ATTRIBUTES


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FACTS Controller Control AttributesStatic Synchronous Compensator(STATCOM without storage)

Voltage control, VAR compensation, damping oscillations, voltagestability

Static Synchronous Compensator

(STATCOM with storage,large dc capacitor)

Voltage control, VAR compensation, damping oscillations, transient

and dynamic stability, voltage stability, AGC

Static VAR Compensator (SVC, TCR,TCS, TRS

Voltage control, VAR compensation, damping oscillations, transientand dynamic stability, voltage stability

Thyristor-Controlled Braking Resistor(TCBR)

Damping oscillations, transient and dynamic stability

Static Synchronous Series Compensator(SSSC without storage)

Current control, damping oscillations, transient and dynamic stability,voltage stability, fault current limiting

Static Synchronous Series Compensator(SSSC with storage)

Current control, damping oscillations, transient and dynamic stability,voltage stability

Thrystor-Controlled Series Capacitor(TCSC, TSSC)


Thyristor-Controlled Series Reactor(TCSR, TSSR)



Active and reactive power control, voltage control, VAR

compensation, damping oscillations, transient and dynamic stability,voltage stability, fault current limiting

Interline Power Flow Controller (IPFC) Reactive power control, voltage control, damping oscillations,transient and dynamic stability, voltage stability

VOLTAGE POWER QUALITY CONDITIONER


45/50

LOAD

~

Is

IL

VS

VX

VI

C

COMPENSATOR

I

LV S

VX

V I

~I

LI

S2mH

0.1mH

25F

0.25m F

1

VS

VI

VC

PLL

VC

*

BLOCK

A

PI+

_VC

VS

'

}ControlSignals

FILTER

VSd

+

+ +

- VS

~

VS

VSd

'

10ms/d

iv

400V/

div

100A/

div

100A/

div

704

V

696V

VS VI

10ms/d

iv

10ms/d

iv

10ms/d

ivIL

IS

VC

10ms/d

iv

400V/d

iv

100A/

div

100A/d

iv

704

V

696V

VS

VI

10ms/d

iv

10ms/d

iv

10ms/d

ivIL

IS

VC

INTERLINE POWER QUALITY CONDITIONER


46/50

r r

11V

21I

r 21V

XX

11I

r

C1Vr

Ir

C1

12V

22Ir 22V

XX

12Ir

r C2V

Ir

r

11 21

12

C2

22

r

DC LINK

SYSTEM 1

SYSTEM 2

SYSTEM 1

11V

r

1CVr

21Vr11I

r

21Ir

1CI

r

211

11

21

221

2111 >

21XVr

11XVr

12Vr

22Vr

12XVr

22XV

r2CVr

2CIr

22Ir12

Ir

2212


47/50

Series vs. Parallel:

Series is more powerful in controlling the current/power flow anddamp oscillations

Parallel is more effective in voltage control and damping of voltageoscillations

FACTS - POSSIBLE BENEFITS


48/50

Control of power flow. Increase the loading capability of lines to their

thermal capabilities.

Increase the system security through raising the transient stability limit,

damping electromechanical oscillations of power systems and machines.

Provide greater flexibility in siting new generation.

Reduce reactive power flows, thus allowing the lines to carry more active

power.

CONCLUSIONS


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Power supply industry is undergoing dramatic change as a result of

deregulation and political and economical maneuvers. This new marketenvironment puts demands for flexibility and power quality into focus. This

calls for the right solutions as far as power transmission facilities between

countries as well as between regions within countries are concerned.

The choice of FACTS device is simple and needs to be made the subject of

detailed system studies, taking all relevant requirements and prerequisites of

the system into consideration, so as to arrive at the optimum technical andeconomical solution. In fact, the best solution may often be lying in a

combination of devices.


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END

Documents

Presentation - Power Electronics Arrangements in Distributed Systems