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Power Quality Improvement by SCCS Using SRF and Park Transformation in PV Grid Integration Systems

Gowthami1 Golla Koti Haritha2 , l

1B.Tech Student, Electrical and Electronics Engineering, Stanley College of Engineering and Technology for Women, Telangana, India

2B.Tech Student, Electrical and Electronics Engineering, Stanley College of Engineering and Technology for Women, Telangana, India

3Assistant professor, Electrical and Electronics Engineering, Stanley College of Engineering and Technology for Women, Telangana, India ***

Abstract - The increasing penetration of renewable energy sources, particularly photovoltaic (PV) systems, into the grid has raised concerns about power quality and reliability. This paper presents a comprehensive analysis and evaluation of power quality enhancement in PV integrated systems using a Unified Power Quality Conditioner (UPQC) with Synchronous Reference Frame (SRF) and Park transformation control strategies. The performance of UPQC with SRF and Park transformation with and without Sinusoidal current control strategies (SCCS), under various non-linear load conditions. The primary objective is to reduce harmonics, sags, swells, and voltage fluctuations, thereby enhancing power quality. The analysis utilizes MATLAB/Simulink software for simulation and comparison of Total harmonic distortion (THD). The results provide valuable insights into the effectiveness of UPQC with SRF and Park transformation for power quality improvementinPVintegratedsystems.

Key Words: Power Quality, UPQC, SRF, Park Transformation,SCCS,PVIntegratedSystemandTHD.

1.INTRODUCTION

The Deployment of photovoltaic (PV) systems has increased significantly globally as a result of the growing needforrenewableenergy.Thesesystemsareessentialto the shift to sustainable energy sources because of their capacity to directly convert sunlight into power [1]. However, there are a number of difficulties in integrating PV systems into the electrical grid, especially when it comes to preserving grid stability and power quality [2]. To overcome these obstacles and improve PV system performance, a number of control solutions have been developed recently. The SRF and Park transformation techniquesaretwoofthesetacticsthathavebecomewellknownbecauseofhow well theyeasethree-phasesystem control and analysis [3]. These techniques enable precise control and grid synchronization by transforming threephasecurrentsandvoltagesintoatwo-phasesynchronous reference frame. To further improve the current and voltage parameters of PV systems, this project proposes

thecombination ofSRF and Park transformationmethods withtheSynchronousCurrentControlStrategy(SCCS)[5]. The SCCS method regulates the electricity that is fed into the grid, ensuring optimal power quality and stability. Additionally, the Second-Order Generalized Integrator (SOGI) based Phase-Locked Loop (PLL) is employed for precise detection of the utility voltage's phase angle, amplitude, and frequency [6]. This project aims to demonstrate the effectiveness of the proposed approach through simulation and experimental validation [7]. By integratingadvancedcontroltechniques,theprojectseeks toimprovePVsystemsperformance,ensuringreliableand efficientintegrationintotheelectricalgrid.

1.1 UNIFIED POWER QUALITY CONDITIONER (UPQC)

A device known as a UPQC (Unified Power Quality conditioner) is used to correct for voltage distortion and imbalance in a power system. This ensures that the voltage at the load side is perfectly balanced, sinusoidal, andregulated[8].Additionally,itcorrectsforloadcurrent harmonics, resulting in a source side current that is perfectlysinusoidalandfreeofdistortionsandharmonics. Shunt Active Power Filter (ShAPF) is used to compensate for load current harmonics and make the source current fully sinusoidal, free from distortions and harmonics [9]. UPQCisa combinationofa ShuntActivePowerFilterand a Series Active Power Filter [10]. The Shunt APF is connected in parallel to the transmission line. APF is connected in series with transmission lines [11].Passive filters used to be employed to compensate for harmonics and voltage distortion, but they are no longer used becauseoftheirnumerousdrawbacks[12].

TheparallelPWMconverterisacontrolledcurrentsource (ShAF), whereas the UPQC is a controlled voltage source (SAF) [13]. A tiny DC capacitor serves as a tiny energystoring component, and the DC link is independent of the power source. When there is a line failure brought on by anexcessivedemandforreactivepoweroravoltagedipin the grid, the Fixed Speed Induction Generator

Godugu

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malfunctionsandiscutofffromthegrid[14].TheUnified Power QualityConditioner(UPQC) systemdepictedinthe diagramisintendedtoimprovepowerqualityinelectrical networks,especiallywhennon-linearloads.Powerfroma source is transferred to a non-linear load via a series couplingtransformer[15].TheUPQCusesbothseriesand shunt components to reduce power quality problems. While a shunt filter and shunt converter are connected in parallel with the power line, a series low pass (LP) filter and series converter are linked in series [16]. The shunt and series converters are connected by a DC link, which permits coordinated operation. Both converters are monitored and controlled by a control system, which modifies their operation by utilizing control signal flow [17].

1.2 LITERATURE SURVEY

In order to effectively convert, regulate, and control electrical energy, power electronics are essential. Power electronics integration has become crucial for optimizing energy generation and high-power quality as renewable energy sources like solar power are increasingly used [18,19]. It emphasizes the use of photovoltaic solar technology, which turns sunlight into power using solar panels. It also covers the significance of power quality monitoring and mitigation, as well as the role that power quality plays in electrical systems [20]. The grid integration of solar photovoltaic (PV) systems presents serious power quality issues, such as flicker, harmonics, imbalance, and voltage sag. The control techniques which areused Park transformationandSynchronous Reference Frame(SRF)theorytoovercometheseproblems[21]. By converting three-phase currents and voltages into a rotating reference frame, SRF theory makes it easier to control and analyses problems with power quality. Park transformation makes analysis and control easier by converting three-phase currents and voltages into a rotating reference frame (dq0) [22].To enhance power quality, unified power quality conditioners (UPQC) and shunt active power filters (SAPF) have been used. These gadgets can improve power quality and lower harmonics when used with sophisticated control strategies like PI and PID controllers. These methods have the advantages ofhigherefficiency,lowerlosses,andbetterpowerquality. By developing SRF theory and Park transformation, scientists can improve grid-integrated solar PV systems' dependability and efficiency even more. Future studies should focus on creating increasingly complex control strategies and using energy storage devices to guarantee grid dependability and stability [23]. Harmonic compensationandfundamental component extractionare two areas where the SRF approach. Combining Sinusoidal Current Control strategy with SRF and Park transformation that can be effective way to manage the inverter output and lessen power quality problems. Particularly in some situations with non-linear loading,

this hybrid technique allows for precise grid synchronization and dynamic power disturbance adjustment.PVgridintegrationSystemwheretheinverter manages power injection and is essential to preserving gridstability[24].

2. METHODOLOGY

2.1 SYNCHRONOUS REFERENCE FRAME STRATEGY (S.R.F)

Inthisapproach,theangle θwithregardtotheα-βframe usedinthep-qtheorydeterminesthereferenceframed-q. For the traditional SRF approach to be employed in aviationpowerutilitiesandeffectivelycompensateforthe neutral current, only minor adjustments are needed. Because the zero-sequence component of current has not beentakenintoaccount,thezero-sequencesubtractblock removesthezero-sequencecurrentfromtheloadcurrent. The output current then only consists of positive and negative sequence components, and following its park transformation, it only consists of instantaneous active and reactive current in the d-q frame. The dc and ac components of the active current are divided by a lowpass filter in order to compensate for the reactive and harmonic currents. By subtracting the load currents from the reference current, the active current passes througha low-passfilterandthesignalfromthedcvoltageregulator iscombinedwithaparkcounter-transformation.

1. Clarke Transformation (Stationary to Alpha-Beta Frame)

[ ] * +[ ]

[ ] [ ] [ ]

[ ] * +[ ]

o , , arethethree-phasevoltages.

o , arethetwo-phasevoltagesinthe alpha-betaframe.

2. Alpha-Beta to d-q Transformation (Synchronous Frame)

[ ] [ ][ ]

o , arethevoltagesinthesynchronous d-qframe.

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o θistheangleofrotationofthe synchronousframe.

3. Inverse Transformation (d-q to Alpha-Beta)

[ ] [ ][ ]

4. Inverse Clarke Transformation (Alpha-Beta to Three-Phase)

[ ]=[ ][ ]

[ ]=* + [ ]

2.2 PARK TRANSFORMATION THEORY

In electrical engineering, the Park Transformation, also called the Direct-Quadrature-Zero (DQ0) transformation, is a mathematical tool that simplifies the analysis and control of three-phase systems by transforming threephasequantities(abc)intotwoorthogonalcomponents(d and q) in a rotating reference frame. This transformation reduces the complexity of control tasks such as current regulation in motor drives and inverters by making AC quantities appear as DC values. The inverse Park Transformation allows the controlled DC quantities to be converted back to three-phase AC signals for real-world applications.

Figure 1:Block diagram of SRF and Park transformation without SCCS

In this block diagram shows the 3-phase generated in the control techniques. source block is generated with fluctuations,voltagesags,swellsandharmonicsinthatsag generated with heavy loads to control the voltage sags by using controllers. The 3-phaseVI measurement is measuring the parameters i.e., voltage and current with RLCloadanddioderectifierthroughnon-linearload.Solar having PV ray’s irradiance to increment or decrement

temperature 25C by connecting the current controlled source. The PN junction integrated with silicon it will be highly generated with boost converter through MOSFET. InthispulsesandgatesignalsgeneratedandSolaroutput inverter is converted DC to AC. Solar is linked with UPQC in that having the SRF and park transformation theory to inverter through a step-up T/F toload.Inthatvolageand current will be generated with pure sinusoidal waveform to reducing these sags, swells and harmonics and improvingthepowerquality.

Step-by-StepDerivationofParkTransformation

1. Three-Phase System:

Consider a balanced three-phase system with the phasevoltages(orcurrents)representedas:

A(t)=

B(t)=

C(t)=

● Am isthepeakvalue.

● ωistheangularfrequency.

● tistime.

2. Transformation to Two-Axis System (d-q axes)

● The goal of the park transformation is to transform these three-phase quantities into a two-axis(d-q)referenceframe.

● Thetransformationmatrixforthisis:

T= ( )

3.Application of Transformation Matrix

The transformed d-axis (Ad) and q-axis (Aq) components can be obtained by multiplying the transformation matrix withtheoriginalthree-phasequantitiesA(t),B(t)andC(t). ( ) =T

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4. Simplification Using Trigonometric Identities

Using trigonometric identities, the d-axis and q-axis componentscanbesimplifiedasfollows:

5. Final d-q Components

Sincethethree-phasequantitiessumtozeroinabalanced system, A0(zero sequence component) is zero. Thus, the finald-axisandq-axiscomponentsare:

level. Thesystem'soperationiscontrolledbyanadvanced controller unit that uses methods like Park transformation, Synchronous Current Control Strategy (SCCS), and Synchronous Reference Frame (SRF). To guarantee the quality of the power sent to the grid, the controller additionally incorporates a Unified Power Quality Conditioner (UPQC). With this whole configuration, solar energy may be integrated effectively, preservinggridstabilityandpowerquality.

2.3.1 SCCS for ShAF (Shunt Active Filter)

Basedonvariousstudiesondifferentcontrolapproachfor ShAF and after observing their drawbacks, the proposed work has been carried out with a simple and old control strategy based on Instantaneous pq-theory. which representing the basic control strategy for shunt inverter controlofa3P3Wsystem.TheShAFisverymuchcloseto the nonlinear load to draw fixed instantaneous power fromthesourceandcompensatetheoscillatingrealpower (p). The ShAF is supplied with a part of oscillating instantaneousactiveloadcurrentina3- systemwithout neutral resulting a zero powered zero-sequence component. [ ] = *

]

The Park transformation converts three-phase quantities A(t),B(t),andC(t)intotwoorthogonalcomponentsAd and Aq in the rotating reference frame. This transformation simplifiestheanalysisandcontrolofACmachinesystems, makingiteasiertounderstandtheirdynamicbehavior.

2.3 Sinusoidal Current Control Strategy (SCCS)

Figure 2:Block diagram of SRF and Park transformation with SCCS

The block diagram shows a system that combines solar energy with a grid system, including synchronization and powerqualitycontrolmethods. Thesystembeginswitha solar panel that transforms direct current (DC) into alternating current (AC) by feeding it into an inverter. Beforebeingsenttotheloadandthegrid,thisACpoweris first sent to a step-up transformer to raise the voltage

Similarly, 3- line current can be converted into 2- by ClarkeTransformationwhichhelpsinestimatingtrueand complex power along with 2- voltage ( ; ). The illustration of the control block of AFC for sinusoidal currentcontroltechnique. [ ]

The benefit of implementing the Clarke transformation is that it converts 3-phase system into 2-phase system and allows independent control in two phases. From the 3 instant powers, i.e., zero sequence component, active (p) and reactive (q) components, the instant phase voltages andlinecurrentsareasfollows:

[ ] = [ ][ ]

Fromtheaboveequationtheactiveandreactivepower P= q=

TheblockdiagramofSCCSepitomizestheentirealgorithm of the controller for 3P3W ShAF which compensates the oscillating true power as well as the complex load power.

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Later with the effect of LPF dynamic and PI-controller, dc voltageregulatoraddressestransients.

= =P-

frompcanberealizedthroughselectionofthepower block to be compensated by a low pass filter with careful selectionofcutofffrequencyduetoimplicitdynamicslead to compensate flaw in transients. The total imaginary powertobecompensatedis:

3.3.2 SCCS for SAF

Intheproposed work,instantaneous p-qtheoryonSAF is applied to a 3P3W system using the same control approach.SAFismeantforvoltagerectification.Theinput for the control block meant for calculation of the instantaneous power PCC phase voltages with the compensation of line currents of the nonlinear load, i.e., a discriminated compensation characteristic for ShAF that performs as an open circuit for harmonic currents as producedbyothernearbynonlinearloads.

[ ] = [ ][ ]

Here the voltages are calculated by the dual pq - theory pretendedwithknowncurrents,trueandcomplexpowers withthevoltagecomponentstobedeterminedduringthe presence of series voltage compensation which is dual of compensationofshuntcurrent)asfollows:

[ ] = [ ]

Theaboveequationleadstooscillatingtruepower(p)and complex power(q) with zerosequence powers and ̃ pretended as zero due to zero-sequence current. Along with oscillating powers, the instantaneous voltages to be injected by the SAF for load harmonic voltage compensationbyusing:

[ ] = [ ]

A certain amount of is added to ̃with an objective to compensate the losses. The reference voltages and areconvertedtoabcreferenceby [ ] = * +

[ ]

SAF is produced by load vibration active performance loadsandgeneratestensionsthatneedtobecorrectedby load harmonic voltage. This method guarantees a pure sinus-shaped waveform for the source-side voltage. SCC based on UPQC makes up the entire system that was inspected.

3.Results and Discussions

Two different control strategies have been simulated using MATLAB/Simulink to evaluate their performance. The simulation results clearly demonstrate that the every one of both schemes are proficient to effectively reduce the significant amount of THD in source current within limits.

A.SRF and PARK TRANSFORMATION (WITHOUT SCCS)

THD Source Current = 23.77%

Figure 5:THD Source Current

The Total Harmonic Distortion (THD) in the source side current is 23.77%, indicating a significant presence of harmonicfrequenciesthatcancompromisepower quality andsystemefficiency.

THD Load Current = 30.87%

Figure 7:THD load current

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The Total Harmonic Distortion (THD) in the load side current is 30.87% without the implementation of SynchronousCurrentControlStrategy(SCCS),indicatinga significant distortion in the current waveform. This high THD value suggests that the load side current is not a clean sine wave, but rather a distorted waveform with a substantial amount of harmonic content. The absence of SCCSresultsin.Increasedharmonicdistortions.

B. SRF and PARK TRANSFORMATION (WITH SCCS)

THD Source Current = 23.23%

Figure 9: THD source current

The Total Harmonic Distortion (THD) in the source side current is 23.23%, indicating a significant presence of harmonicfrequenciesthatcancompromisepowerquality andsystemefficiency.

Figure 11:THD Load current

The Total Harmonic Distortion (THD) in the load side currentis0.81%withtheimplementationofSynchronous Current Control Strategy (SCCS), indicating a significant improvement in power quality. The SCCS has effectively reduced the harmonic distortion, resulting in a perfect sinewave,Minimalenergylosses.

The implementation of SCCS has achieved a remarkable reduction in THD, from 30.87% to 0.81%, demonstrating its effectiveness in mitigating harmonic distortion and improving the overall performance of the electrical system.

Table 1:SRF and Park Transformation without SCCS

SRF and Park Transformation

Comparing the percentages of Total Harmonic Distortion (THD)forSourceCurrentandLoadCurrentunderSRFand Park Transformation conditions without SCCS (Sinusoidal currentcontrolstrategy)isshowninthetable. At30.87%, theTHDforloadcurrentishigherthantheTHDforsource current, which is recorded at 23.7%. Under the given circumstances, this suggests that the Load Current is subjecttoahigherdegreeofharmonicdistortionthanthe SourceCurrent.TheabsenceofSinusoidalCurrentControl Strategy(SCCS)canleadtoincreasedharmonicdistortion, potentially causing overheating and equipment damage, which underscores the importance of effective control strategiesinmaintainingoptimalsystemperformanceand preventingdetrimentaleffectsonelectricalequipment.

Table 2:SRF and Park Transformation with SCCS SRF and Park Transformation with SCCS

The table presents the Total Harmonic Distortion (THD) percentagesforSourceCurrentandLoadCurrentwithSRF (SynchronousReferenceFrame)andParkTransformation withSCCS(SinusoidalCurrentControlStrategy).TheTHD for the Source Current is 23.23%, while the THD for the Load Current is significantly lower at 0.81%. This indicates that the SCCS effectively reduces harmonics in theloadcurrent,resultinginacleanerpowersupplytothe load compared to the source. The control strategy effectively filters out harmonics from the source current, protecting the load from distortion and ensuring a highqualitypowersupply.

3. CONCLUSIONS

This project demonstrates the effectiveness of Unified Power Quality Conditioner (UPQC) in improving power quality in a 3-phase system under non-linear load conditions. This enables the development of advanced

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power quality conditioning systems for renewable energy applications, facilitating smooth integration of solar energy into the grid. The comparison between the Synchronous Reference Frame (SRF) & Park transformation with and without Sinusoidal Current Control Strategy (SCCS) significally improving power quality and reducing harmonics, sags, swells and voltage fluctuations. The analysis utilizes MATLAB/Simulink softwareforsimulationandcomparisonofTotalHarmonic Distortion (THD) with and without SCCS and improving power quality. This is achieved by the UPQC ability to compensatefortheharmoniccurrents,resultinginamore sinusoidal and stable power supply. The analysis highlights the potential of UPQC with SCCS to enhance power quality in grid-tied photovoltaic (PV) systems, particularlyundervaryingirradianceconditions

REFERENCES

[1] S. Kr. Tiwari, B. Singh, P.K. Goel, Design and control of micro-grid fed by renewable energy generating sources, IEEE Trans. Ind. Appl. (2018) 1, https://doi. org/10.1109/TIA.2018.2793213,1.

[2] Z. Zaheeruddin, M. Manas, Renewable energy management through microgrid central controller design: an approach to integrate solar, wind and biomass with battery, Energy Rep. 1 (2015) 156–163, https://doi.org/10.1016/j.egyr.2015.06.003.

[3] Y.V. Pavan Kumar, B. Ravikumar, Renewable energy based micro grid system sizing and energy management for green buildings, J. Mod. Power Syst. Clean Energy 3 (March1)(2015)1.-1.

[4]G.Rizzo,Automotiveapplicationsofsolarenergy,IFAC Proceed.Vol.43(July7)(2010)174–185.

[5] L. Li, B. Loo, Alternative and transitional energy sources for urban transportation, Curr. Sustain. /Renew. Energy Rep 1 (2014), https://doi.org/10.1007/s40518014-0005-6

[6]Karthikeyan,V.,Rajasekar,S.,Das,V.,Pitchaivijaya,K.& Singh, A.. (2017). Grid connected and off-grid solar photovoltaicsystem.10.1007/978-3-319-50197-0_5.

[7] O. Arafa, A. Mansour, K. Sakkoury, Y. Atia, M.M. Salem, Realizationofsingle-phasesingle-stagegrid-connectedPV system, J. Electr. Syst. Inf. Technol. (2016), https:// doi.org/10.1016/j.jesit.2016.08.004.

[8] L. Gyugyi, Unified power flow control concept for flexible ac transmission systems, Proc. IEE 139(C) (1992) 323–331.

[9] S. Munir, L. Yun Wei, Residential distribution system harmonic compensation using PV interfacing inverter, IEEETrans.SmartGrid.4(2)(2013)816–827.

[10] R.C. Dugan, M.F. McGranaghan, H.W. Beaty, Electrical PowerSystemsQuality,McGrawHill,NewYork,1996.

[11] H. Fujita, H. Akagi, The unified power quality conditioner, the integration of series- and shunt-active filters,IEEETrans.Power.

[12]B.Singh,K.Al-Haddad,A.Chandra,Areviewofactive filters for power quality improvement, IEEE Trans. Ind. Electron. 46 (5) (1999) 960–971, https://doi.org/ 10.1109/41.793345.

[13]MaurícioAredes,Luís.F.C.Monteiro,JaimeM.Miguel, “Control Strategies for Series and Shunt Active Filters,” IEEE Bologna Power Tech Conference, June 23th-26th, Bologna,Italy,2003,pp.101-106.

[14] Mauricio Aredes, Jurgen Hafner, Klemens Heumann, “Three-Phase Four-Wire Shunt Active Filter Control Strategies,” IEEE Transactions on Power Electronics, Vol. 12,No.2,pp.311-318,March1997.

[15] M.A. Omar, M.M. Mahmoud, Design and simulation of a PV system operating in grid-connected and stand-alone modesforareasofdailygridblackouts,Int.J.Photoenergy 2019 (2019) 9. Article ID 5216583, https://doi.org/10.1155/2019/5216583.

[16] V. Khadkikar, enhancing electric power quality using UPQC: a comprehensive overview, IEEE Trans. Power Electron.27(5)(2012)2284–2297

[17] S. Devassy, B. Singh, Modified P-Q theory, based control of solar PV integrated UPQC-S, in: Proceedings of IEEE Industry Application Society Annual meeting, Portland, USA, IEEE Press, 2016, pp. 1–8, 2–6 October 2016Piscataway.

[18]BalogR.S.,Z.Sorchini,J.W.Kimball,P.L.Chapman,and P.T.Krein,“ModernLaboratory-

[19] Blaaberg F. et al., The Future of Electronic Power Processing and Conversion, IEEE Transactions on IndustryApplications,Vol.41,pp.3-9,2005.

[20] Carasco J.M. et al., Power-Electronic Systems for the GridIntegrationofRenewableEnergy

[21]Tuyen,NguyenDucandGoroFujita,"PV-activepower filter combination supplies power to nonlinear load and compensates utility current", IEEE power and energy technologysystemsjournal2.1,2015.

[22]ZHOUFang-yuan,TANGZhao-hui.Activepowerfilters and their development[J]. Electrical Measurement and Instrumentation,2005,8(8):1-4.

International Research Journal of Engineering and Technology (IRJET) e-ISSN:2395-0056

[23]DAILie-feng,JIANGPing,TIANDa-qiang.Realizationof harmaniccurrentdetectionofd-qtransformationwithout phaselockloop[J].PowerSystem

[24] Akagi H., Nabae A.: The p-q theory in three-phase systems under non-sinusoidal conditions. Eur. Trans. Electr.PowerEng.3(1),27–31(1993)