VOLTAGE SAG AND SWELL ALLEVIATION IN DISTRIBUTION NETWORK USING CUSTOM POWER DEVICES; D-STATCOM AND DVR. by Abdullahi Kunya, T. Yalcinoz, Gaddafi Shehu

VOLTAGE SAG AND SWELL ALLEVIATION IN DISTRIBUTION NETWORK USING CUSTOM POWER DEVICES; D-STATCOM AND DVR.

Presented

By

Gaddafi Sani Shehu

INTRODUCTION

• Due to rapid technological innovations and hike in world population,high quality and reliable electrical power demand has significantlyincreased recently which is roughly estimated to double by nextdecade.

• This heavy burden on the present traditional power systems leads tomany power quality problems; voltage inconstancy, poor reliability,frequency fluctuations, caused on transmission and distribution lines.

• More than 90% of all the problems in power systems are consequent tovoltage sags and swells.

To overcome these hurdles, wide range of power electronics devicesemerged and modified to improve their performance.

• Second generation power Electronics devices under the umbrella ofFlexible Alternating Current Transmission System (FACTS) andCustom Power (CP) are the best option when it comes to voltagestability, reactive power compensation, power factor correction andharmonics level reduction.

• Among these devices, D-STATCOM and DVR have shown anexceptional performance due to their fast response and real-timecontrol ability.

CUSTOM POWER DEVICES; D-STATCOM AND DVR

Distribution Static Compensator (D-STATCOM)

DSTATCOM Schematic representation

D-STATCOM TEST DISTRIBUTION SYSTEM

3.5 [ohm]

#1#2

dcCur DC Current

1

2

800.0 [uF]

3

2

5

2

4

2

6

2

2

2V_dc

DC Voltage

IL

RMS Voltage

Vpu

150 [ohm]

1.35 [H]

V

A

Bus 1

g4g6

g2 g5g3

g1

Vpu PWM

Control

Voltage

ControlVpu Shft

Bus 2

TimedBreaker

LogicOpen@t0

SWITCHB

SWITCHA

TimedBreaker

LogicOpen@t0

SWITCHA

RL

SWITCHB

26.0 [ohm]

V

A

Capacitive

load20 [uF]

Coupling

TransformerBalanced three phase fault, for

creating voltage sag at a

simluation period of 0.25sec and

lasted for additional 0.25sec.

D-STATC...

Vn

Inst. Voltage

TimedFaultLogic ABC

1.0 [oh

m]

0.33 [H]

Measurements and

Controls

DYNAMIC VOLTAGE RESTORER (DVR)

. DVR building components

DVR TEST DISTRIBUTION SYSTEM

dcCur DC CurrentdcVltg DC Voltage

FAULTSC

B

A

ABC->G

TimedFaultLogic

RMS Voltage

Vpu

VpuPWM

Control

Voltage

Contol

Vpu Shft

BRK2

Instanteneous Voltage

Vn

5.25 [ohm]

1

2

350.0 [uF]

3

2

5

2

4

2

6

2

2

2

V

A

g4g6

g2 g5g3

g1

BRK2

BRK3

BRK1

BRK3

BRK1

#1#2

TimedBreaker

LogicClosed@t0

0.02263 [H]

0.02263 [H]

0.02263 [H]

.55 [ohm]

.55 [ohm]

#1#2

#1#2

R=0

Balanced Three Phase Fault for

creating the Voltage Sag at 0.75

sec which lasted for 1.00 sec

By-Pass Switches

Controls

Voltage Source

Converter

By-Pass Switches

Coupling

Transformers

Voltage and PWM

Controls

TimedBreaker

LogicClosed@t0

TimedBreaker

LogicClosed@t0

A

B

C

R=0

C

B

A

SWTCH

SWTCH

TimedBreaker

LogicOpen@t0

V

A

0.0052 [ohm]

A

B

C

A

B

C11 [kV]

#2#1

11 [kV]

100.0 [MVA]2.50 [uF]0.0052 [ohm]

0.0052 [ohm] 2.50 [uF]

2.50 [uF]

1.0 [ohm]

1.0 [ohm]

1.0 [ohm]

TEST SYSTEM AND SIMULATION RESULTS

(D-STATCOM SIMULATIONS AND RESULTS)

• Voltage Variation at Load Point without D-STATCOM • Voltage Variation at Load Point with D-STATCOM

System Voltage at PCC w ithout D-STATCOM

Time(s) 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 ...

...

...

0.00

0.20

0.40

0.60

0.80

1.00

1.20

Voltage (

pu)

RMS Voltage w ithout D-STATCOM

-15.0

-10.0

-5.0

0.0

5.0

10.0

15.0

Voltage (

kV

)

Instanteneous Voltage Without D-STATCOM

System voltage at PCC w ithout D-STATCOM

Time(s) 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 ...

...

...

0.00

0.20

0.40

0.60

0.80

1.00

1.20

Voltage

(pu)

RMS Voltage w ithout D-STATCOM RMS Voltage w ith D-STATCOM

-10.0

-5.0

0.0

5.0

10.0

Voltage (

kV)

Instanteneous Voltage w ith D-STATCOM

SUMMARY OF VOLTAGE SAG AND SWELL

ALLEVIATION USING D-STATCOM.

Voltage SimulationTime (sec)

WithoutDSTATCOM

WithDSTATCOM

RMS(pu)

Normal supply 0.952 0.998

0.25 ≤ ts ≤ 0.50 0.793 0.995

0.75 ≤ ts ≤ 1.00 1.146 1.002

Instantaneous(kV)

Normal supply 10.472 10.978

0.25 ≤ ts ≤ 0.50 8.778 10.945

0.75 ≤ ts ≤ 1.00 12.606 11.022

DVR SIMULATIONS AND RESULTS

System voltage at PCC w ithout D-STATCOM

Time(s) 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 ...

...

...

0.00

0.20

0.40

0.60

0.80

1.00

1.20

Volta

ge (

pu)

RMS Voltage w ithout DVR RMS Voltage

-10.0

-5.0

0.0

5.0

10.0

Volta

ge (k

V)

Inst. Voltage

SUMMARY OF THE RESULTS

Voltage SimulationTime (sec)

Without DVR With DVR

RMS(pu)

Normal supply 0.932 0.998

0.25 ≤ ts ≤ 0.50 1.140 1.001

0.75 ≤ ts ≤ 1.00 0.778 0.996

Instantaneous(kV)

Normal supply 10.252 10.978

0.25 ≤ ts ≤ 0.50 12.540 11.011

0.75 ≤ ts ≤ 1.00 8.558 10.956

CONCLUSION • An electromagnetic transient model of embedded Distribution Static Compensator

(D-STATCOM) and that of Dynamic Voltage Restorer (DVRs) has been presentedusing PSCAD/ETDMC software to test the efficacy of these devices in assuagingvoltage dips and swells.

• The devices presented have shown great performance in alleviating thedisturbances. It can be deduced from the results obtained that DVR clears thevoltage instability and restores system voltage much better than D-STATCOM.

• Additional benefit derivable from these schemes is the absence of filter componentas the reactance of the coupling transformers serve that purpose.