250kva unified power quality controller

250kVA Unified Power Quality Controller

P. Ganesan, R. Sudeep Kumar Power Electronics Group

Centre for Development of Advanced Computing (CDAC), Trivandrum, India

[email protected] , [email protected]


Overview of the PresentationIntroduction to Power Quality Problems and Solutions

Overview of Unified Power Quality Controller

Specification of 250kVA Unified Power Quality Controller

Power circuit configuration of 250kVA UPQCConverter topology of Shunt Compensator Converter topology of Series CompensatorPower circuit

Test results and field trial of the UPQC

Conclusion

1/26


Power Quality Affected by Polluting Load

LOAD

PollutingLoad

A

B

PCC

Distorted voltagePure Sinusoidal

2/26


Two Main Power Quality Problems

Harmonics and Reactive current drawn by the loads.

Voltage Sag,Swell,Unbalance etc.

3/26


Modern Power Quality Solutions

Shunt Active Filter (STATCOM)

Series Active Filter

(Dynamic Voltage Restorer)

4/26


STATCOM

Vdc

Vpcc Isat

Vsat

Ls

CompensatesReactive CurrentHarmonic Current

5/26


Dynamic Voltage Restorer(DVR)

Vdc

VloadVdvrVgrid

CorrectsVoltage sag and Swell

Voltage unbalanceVoltage flicker

6/26


Single Line diagram of Unified Power Quality Controller (UPQC)

GRID

VGRID IGRID

LOAD

Vdvr

Idvr

I FILTER

Vdc

Series Active Filter

Shunt Active Filter

7/26


Power Flow Control of UPQCUnder Nominal Voltage Condition

CONTACTOR TRANSFORMER LOAD

SHUNTAF

SERIESAF

3 Phasegrid

Supply

VOLTAGE

CURRENT

POWER

100%

100%

100%

100%

100%

100%

100%

100%

100%

0% 0%

8/26


Power Flow Control of UPQCUnder Low Voltage Condition


SHUNTAF

SERIESAF

3 Phasegrid

Supply

VOLTAGE

CURRENT

POWER

90%

110%

100%

10%

100%

110%

110%

100%

100%

100%

10%10%

9/26


Power Flow Control of UPQCUnder High Voltage Condition


SHUNTAF

SERIESAF

3 Phasegrid

Supply

VOLTAGE

CURRENT

POWER

110%

90%

100%

100%

90%

90%

10%

100%

100%

100%

10%10%

10/26


UPQC System SpecificationInput Voltage :415V, 3 Phase, +10%, -15%, 50 Hz

Output Voltage :415V, 3 Phase, +/- 1%, 50 Hz(phase voltages will be balanced)

Rating :250kVA(output load)

Power Factor :Will be maintained at near Unity at thegrid side

Configuration :IGBT Inverter 1x3 Ø bridge for shunt

Cooling :Forced Air

Ambient temperature :45o C

Enclosure :Suitable for indoor application

Digital Controller :DSP based controller

3x1 Ø bridge for series

11/26


Converter Topology

CapacitorBank

+

R

+ve Bus

-ve BusY B

Shunt Compensator

No of Switches : 6

Series Compensator

CapacitorBank

+

P

+ve Bus

-ve BusN

No of Switches : 12 ( 4 *3 )

12/26


Power Circuit Vgr

L

O

A

D

R1

R2

C1

415V ACContactor

CR1Igr

Igy

Igb

PTVgyVgb

R

Y

B

N

C11 C12

C13 C14

C15 C16

TRX 1

TRX 2

TRX 3

PT5PT4

Vdr

PT6

VdyVdb

CR2415V ACContactor

C2

C3

C4

R3

R4

C5

C6 C8

C7

Ishr Ishy

MAIN SMPS & GATE

DRIVER SMPS

C9

C10

R5

R6

DCF/BCkt

VdcL1 L2 L3

Id1 Id2 Id3

DB1SSR 3

R7

R8

TRX 4DB2

415 V

L4

F1 F2 F3

S4-S9

SERIES ACTVE FILTER SHUNT ACTIVEFILTER13/26


Shunt compensator control Block Diagram

Current Load

magnitude Voltage Grid

+−

*dcV

dcV

cb,a,βα, LPF

+−

βα,qd,

qI l

VectorUnit

cb,a,βα,

βα,qd,

qI i

dI i +−

ωL

ωL

+−

++

++

*idV

*iqV

STATCOMCurrent

14/26


Control Scheme for Series Active Filter

Grid

IL

VLoad

Iinv IP

Load

1: N

Lf

Cf VcVdc

SA

SA SB

SB

⎟⎠⎞⎜

⎝⎛ −

∗+= VloadVload(ref)

TvcNf

CIpIinv(ref)

( )IinvIinv(ref)TiLNfL

VcVinv(ref) −∗

+=

15/26


Control Hardware18 Analog Input channels

32K word of RAM

CY7C1020

TMS 320F240

6 PWM

DSP

ADC interface(on-chip + external)

PWM Interface

FPGA12 PWM

For 3x1ØSeries

Compensator

6 PWMFor

Shunt Compensator

DACInterface

Monitoring3PWM

3 PWM

Fault Interface

I/O Interfaces

RS 232 Driver

Fault Signal

from IPM

16/26


Digital Controller

TMS 320F240 DSPFPGA

17/26


Performance Evaluation of 250kVA UPQC

Grid Voltage(V)

Grid Current(A)

Load Voltage(V)

Load Current(A)

Vgrn Vgyn Vgbn Igr Igy Igb Vlrn Vlyn Vlbn Ilr Ily Ilb

239 238 240 56 77 63 221 219 220 70 88 75

237 236 238 53 73 59 220 219 220 63 82 64

240 240 240 43 66 53 221 220 219 55 76 58

Readings at different load

B0.850.850.85

Grid Power Factor Load Power Factor

R B0.97 0.970.97 0.980.98

Y0.980.980.97 0.98

R Y0.78 0.820.78 0.810.80 0.82

Grid and Load Power Factor

18/26


Performance Evaluation of Shunt Active Filter

3 Phase AC Supply

3x1 Ø Series Active Filter

1x3 Ø Shunt Active Filter

120kVA UPS withfront end 6 pulse Thyristor rectifier

Grid current before

Compensation

Grid current after

Compensation

THD3579

11

Harmonics Before HarmonicCompensation (%)

131517

9.40.72.18.20.3

1.9 2.60.1 0.4

After HarmonicCompensation (%)

4.50.40.41.9

0.21.72.30.30.3 19/26


Performance Evaluation of Shunt Active Filter

Grid Current before compensation

Grid Current after compensation

Harmonic Spectrum before compensation Harmonic Spectrum after compensation

20/26


Performance Evaluation of Series Active Filter

Buck Mode

Vset = 210V Channel1-R phase Grid Voltage Channel2-R phase Load Voltage

Boost Mode

Vset = 270V Channel1- Y –phase Grid Voltage Channel2- Y –phase Load Voltage

21/26


Transient Response of Series Active Filter

Vset = 210V (r.m.s) to 270V (r.m.s)

Step input

Channel1 – R-phase Grid Voltage Channel2 – R phase Load voltage

22/26


250kVA UPQC at C-DAC Lab in India

23/26



Shunt AF Power stack

Series AF Power stack

Shunt AF Coupling Inductor

Sensors

Series AF Coupling

Transformers

Cooling Fan

Series AF LC Filter

24/26



Shunt AF Power stack

Series AF Power stack

25/26


Conclusions on UPQC

UPQC can mitigate Voltage sag,swell and Unbalance

UPQC can supply VAR to load

It isolates the load current harmonics from flowing to the utility

It maintains unity input power factor at all conditions

Dynamic response is fast

26/26


Thank you


250kva unified power quality controller

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