MODELING AND SIMULATION OF DSTATCOM FOR POWER QUALITY

ISSN (Print) : 2320 – 3765 ISSN (Online): 2278 – 8875

International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering (An ISO 3297: 2007 Certified Organization)

Vol. 5, Issue 6, June 2016

Modeling and Simulation of DSTATCOM for Power Quality Enhancement in Distribution System N.Raveendra1, V.Madhusudhan2, A.Jaya Laxmi3 Associate Professor, MRECW, Telengana, India1 KSRM College of Engineering, Andhra Pradesh, India2 JNTUH College of Engineering, Andhra Pradesh, India 3 ABSTRACT: This paper presents the systematic procedure of the modelling and simulation of a Distribution STATCOM (D-STATCOM) for power quality problems with unbalanced load a based on four different Pulse Width Modulation techniques. Power quality is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure of end use equipment’s. The major problems dealt here is the voltage, swell and with unbalanced loads. To solve this problem, custom power devices are used. One of those devices is the Distribution STATCOM (DSTATCOM), which is the most efficient and effective modern custom power device used in power distribution networks. D-STATCOM injects a current in to the system to correct the voltage sag, swell and unbalanced load. The control of the Voltage Source Converter (VSC) is done with the help of SPWM, SVPWM, sub-harmonic PWM and Triangular PWM. The proposed D-STATCOM is modelled and simulated using MATLAB/SIMULINK software. KEYWORDS: Distribution STATCOM (DSTATCOM), MATLAB/ SIMULINK, Power quality problems. I.POWER QUALITY PROBLEMS The power disturbances occur on all electrical systems, the sensitivity of today's sophisticated electronic devices make them more susceptible to the quality of power supply. For some sensitive devices, a momentary disturbance can cause scrambled data, interrupted communications, a frozen mouse, system crashes and equipment failure etc [2]. A power voltage spike can damage valuable components. Power quality problems encompass a wide range of disturbances such as voltage sags, swells, flickers, harmonic distortion, impulse transients, and interruptions. II.DISTRIBUTION STATIC COMPENSATOR (D-STATCOM) A D-STATCOM (Distribution Static Compensator), which is schematically depicted in Fig.1, consists of a two-level Voltage Source Converter (VSC), a dc energy storage device, a coupling transformer connected in shunt to the distribution network through a coupling transformer. Suitable adjustment of the phase and magnitude of the DSTATCOM output voltages allows effective control of active and reactive power exchanges between the D-STATCOM and the ac system. Such configuration allows the device to absorb or generate controllable active and reactive power [7]. The D-STATCOM has been utilized mainly for regulation of voltage, correction of power factor and elimination of current harmonics. Such a device is employed to provide continuous voltage regulation using an indirectly controlled converter. In this paper, the D-STATCOM is used to regulate the voltage at the point of connection. The control is based on sinusoidal PWM and only requires the measurement of the rms voltage at the load point.

Copyright to IJAREEIE

DOI:10.15662/IJAREEIE.20156.0506151

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Fig.1.Schematic diagram of D-STATCOM. The shunt injected current Ish can be written as, ISH=IL-IS Where Is= Therefore ISH=IL-IS=ILOr The complex power injection of the D-STATCOM cab be expressed as SSH=VLISH It may be mentioned that the effectiveness of the D-STATCOM in correcting voltage sag depends on the value of ZTH or fault level of the load bus. When the shunt injected current ISH is kept in quadrature with VL, the desired voltage correction can be achieved without injecting any active power into the system. On the other hand, when the value of ISH is minimized, the same voltage correction can be achieved with minimum apparent power injection into the system. III.METHODOLOGY To enhance the performance of distribution system, D-STATCOM was connected to the distribution system. DSTATCOM was designed using MATLAB - SIMULINK version R2010b [6]. D-STATCOM Simulations and Results for THD Total harmonic distortion, or THD, is the summation of all harmonic components of the Voltage or current waveform compared against the fundamental component of the voltage or current wave: IV.SIMULATION MODEL AND RESULTS DSTATCOM for mitigating power quality problems like UPF, ZVR and load balancing in 3-phase 4-wire distribution network.4 leg inverter is used for the compensation purpose and .synchronous reference frame theory based controller is used for the control of DSTATCOM.


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Vol. 5, Issue 6, June 2016 a.

Simulation model without DSTATCOM. s TH ig nal D

Dis cret e, T s = 5e -00 5 s .

sco p e 5

sc op e 6

p owe rg ui

0.0 2 0 3 4 Disp l a y sco p e 2

Iso u rce

Vt

[Vt]

[Il o ad ]

sig THD na l

Il o a d1

sco pe 3

N

A

A

B

B

C

41 5v 5 0h z

Va bc Ia bc a

A

Va bc

B

Ia bc a

C

b c

C

[Ip cc ] Va bc

A

1

Ia bc

B

b c

a b

C

c

V l,Il

t

A B C

Aa

Bb

Cc

Vs ,Is

a

b

C

A

B c

b

C

B a

Iabc

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Bre ak er

vi

+ -i

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BB

AA

c

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+ -i

A B C

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-

+

B

g +

From 3

-

A

g

A

[Ipu l se ]

f(u) Fcn 1

b oo l e a n

g a te pu l ses + v -

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NOT

d o u bl e

[V d c1 ]

PI

2

Ucr

Discre te P I C o ntrolle r

[V d c1 ] 2 nd -Ord e r Fi l te r4

Fro m 1

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I abc_ c

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D iscre te 3- pha se PLL

-T-

Co n stan t1

Sco p e 9

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0

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2 nd -Ord e r Fi lte r3

D iscrete PI Co ntro lle r1

Sco p e 2

3 42 Co n sta n t2

Fig.2. Simulation model of without DSTATCOM.

Fig.3.Source voltage and source current and load current without DSTATCOM.

Fig.4.Total harmonic distortion for without DSTATCOM. Fig.2.shows the Matlab/Simulation diagram of the without DSTATCOM,Fig.3.shows the sourec Voltage and current, load current.Fig.4. shows the source current THD for Without DSTATCOM.


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Vol. 5, Issue 6, June 2016 2. b.

COMPARISON OF DIFFERENT PWM TECHNIQUES WITH DIFFERENT DISTURBANCES Carrier based PWM simulation model: Discrete, Ts = 1e-005 s. pow ergui

A

Vabc A

b2

B

c2 B

C

C

B C

a

a3

B b

b3

Three-Phase Source

A

B C

Three-Phase Series RLC Branch1

a2

A

A

T hree-Phase Breaker1

c3 cC

T hree-Phase T ransformer (Three Windings) A

B

C

a

b

c

T hree-Phase V-I Measurement

a

A

A

A

b

B

B C

B C

c

C

Three-Phase Breaker2

T hree-Phase Series RLC Branch2

Mag abc

Universal B

a B b cC

V a bcA

Phase

Three-Phase V-I Measurement1

3-P1

g + A

P D

S

B -

Scope1

C

Dis2 3-P

Pulses Uref

Mag abc

Subsystem1

Phase

Te v inv _ref

dlata

PI

1

Constant

Fig.5.Simulation model of with DSTATCOM control of carrier based PWM.

Fig.6.Source voltage and source current and load current with DSTATCOM.


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Fig.7. Total harmonic distortion for with DSTATCOM for carrire baseed PWM. Fig.5.shows the Matlab/Simulation diagram of the with DSTATCOM,Fig.6.shows the sourec Voltage and current, load current.Fig.7. shows the source current THD for With DSTATCOM for carrire based PWM. c. Sinusoidal PWM: a2 A

Vabc A

b2

A

c2 B

B

a

a3

C

B b

b3

Three-Phase Source

C

A

A

B

B

C

C


c3

Three-Phase Transformer (Three Windings)

cC

A

A

Three-Phase V-I M easurement

B

B

C

C

Discrete, Ts = 1e-005 s. pow ergui C

B

A

Three-Phase Series RLC Branch1 Thre

Universal B g + A

P D

S

B -

Scope1

C

Dis2 3-P Puls es Uref Mag abc

Subsystem1

Phase

Te v inv _ref

dlata

PI

1

Constant

Fig.8. Simulation model of with DSTATCOM control of sinusoidal PWM.

Fig.9. Sources current Total harmonic distortion with DSTATCOM for sinusoidal PWM. Copyright to IJAREEIE

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Vol. 5, Issue 6, June 2016 Fig.8.shows the Matlab/Simulation diagram of the with DSTATCOM control of sinusoidal PWM,Fig.9. shows the source current THD for With DSTATCOM. D.Sub-harmonics PWM: signa T HD l

Discre te, T s = 5e-0 05 s.

scope 5 scope 6

p owergu i

Di splay scope 2

Isource

Vt

[Vt]

[Il oad]

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Iload1

scope 3 A A N

B

A Vabc Iabc B

B

a b c

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415v 50hz

C

[Ipcc]

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A

1

B

b c

C

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c

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A A B B C C Aa

Bb

Cc

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a

b

c

Ic

B

A

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vi

+ i -

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C

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B

-

-

+

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g

C

From3

A

g

A

[Ipulse]

f(u) Fcn1

boolean NO T

gate pul ses + v -

Scope5

PI

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2

Ucr

Scope12

Discrete PI C ontroller

[Vdc1] 2nd-Order Filter4

From1

doubl e

[Vdc1]

LPF Scope3 Scope7

[Iload]

I abc_c

a bc From

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Pulses

dq0

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I abc*

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abc_to_dq0 Transformation

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1 Gai n1

Goto8 Freq [Il]

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-K-

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0

Termi nator1

Gain2

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wt Constant1

Scope9

Scope1

Sin_Cos

Discrete 3-phase PLL

0

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Scope4 Scope6 Scope8 Fo=50Hz [Vt] From2

Scope10

PI f(u) Fcn

2nd-Order Fi lter3

Discrete PI C ontroller1

Scope2

342 Constant2

Fig.10. Simulation model of with DSTATCOM control of Sub-harmonics based PWM.

Fig.11. Source current Total harmonic distortion with DSTATCOM for sub-harmonics based PWM. Fig.10.shows the Matlab/Simulation diagram of the with DSTATCOM control of sub-harmonics based PWM, Fig.11. shows the source current THD for With DSTATCOM.


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Vol. 5, Issue 6, June 2016 e.Space Vector PWM a2 A

b2

A

c2 B

B

a3

C

b3

Three-Phase Source

C

Vabc A

Scope2 a B b

A

A

B C

B C


c3

Three-Phase Transformer (Three Windings)

cC

Three-Phase V-I Measurement

Discrete, Ts = 1e-005 s. pow ergui

A B

A B

C

C

C

B

A

Three-Phase Series RLC Branch1 Thre

Universal B g + A

P D

S

B C

Scope1

Pulses

Discrete SV PWM Generator

Fig.12. Simulation model of with DSTATCOM control of space vector based PWM.

Fig.13. Source current Total harmonic distortion with DSTATCOM for Space Vector based PWM.


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Vol. 5, Issue 6, June 2016 Table 1. Comparision table of PWMs Types of PWMs

THD (%)

Sinusoidal PWM Carrier based/Triangular PWM Sub-harmonic PWM SVPWM

5.30 2.74 1.89 0.11

V.CONCLUSION This paper has presented the power quality problem such as total harmonic distortion in the distribution system and simulation technique of a D-STATCOM. The simulation results with different PWMs show that, by adding LCL Passive filter to D-STATCOM, the THD reduced within the IEEE STD 519-1992. The power factors may also increase close to unity. Thus, it can be concluded that by adding D-STATCOM with LCL filter and SVPWM the power quality is improved and THD is reduced. REFERENCES [1] O. Anaya-Lara, E. Acha, "Modeling and analysis of custom power systems by PSCAD/EMTDC," IEEE Trans. Power Delivery, vol. 17, no. I, pp. 266-272, January 2002. [2] S.V. Ravi Kumar, S. Sivanagaraju, "Simualgion of D-Statcom and DVR in power system," ARPN jornal of engineering and applied science, vol. 2, no. 3, pp. 7-13, June 2007. [3] Noramin Ismail, Wan Norainin Wan Abdullah, "Enhancement of Power Quality in Distribution System Using D-STATCOM, " The 4th International Power Engineering and Optimization Conference (PEOCO2010), Shah Alam, Selangor, MALAYSIA. 23-24 June 2010. 4] G. Venkataramana, and BJohnson, "A pulse width modulated power line conditioner for sensitive load centers," IEEE Trans. Power Delivery,vol. 12, pp. 844-849, Apr. 1997. [5] Rosliomar, Nasrudinabdrahim and Mazizansulaiman "Modeling and simulation for voltage sags/swells mitigation using dynamic voltage restorer (DVR), " journal of theoretical and applied information technology, pp 464-470. [6] Bhattacharya Sourabh, "Applications of DSTATCOM Using MATLAB/Simulation in Power System," Research Journal of Recent Sciences, Vol. 1(ISC-2011), pp 430-433 (2012). [7] RoddaShobha Rani, B. Jyothi, "VSC Based DSTATCOM & Pulse-width modulation for Power Quality Improvement," International Journal of Engineering Trends and Technology- Vol. 2, pp 38-41, 2011. [8] M. Mohammadi, M. AkbariNasab, "Voltage Sag Mitigation with D-STATCOM In Distribution Systems," Australian Journal of Basic and Applied Sciences, 5(5), pp 201-207, 2011.


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MODELING AND SIMULATION OF DSTATCOM FOR POWER QUALITY

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