SSRG International Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – volume 1 Issue 9 –November 2014 Design and Analysis of Fuzzy Logic Control Current Source Inverter for Grid Connected PV System. Y.Santhosh *1, Kurva Mallikarjuna*2, M-Tech Student Department of EEE, VBIT, Aushapur, Ghatkesar, R.R (Dt), Telangana, India. Assistant Professor, Department of EEE, VBIT, Aushapur, Ghatkesar, R.R (Dt), Telangana, India. ABSTRACT The SVPWM based voltage source inverter topology is used for grid interfacing of DG system to employ a power conditioning photovoltaic unit is normally required to another photo electric converter stage. The current source inverter offers many advantages over VSI in terms of boosting and short circuiting protection capabilities including the direct current controllability and ac-side simpler filter structure. The research on SVPWM based DG is still development state where this paper focus on modeling and controlling and steady state transient performance of a PV system based on CSI by performing a comparative performance analysis of VSI and CSI based PV system under transient fault conditions are verified using MATLAB/Simulink software based on detailed system model. Key Words: Control, Photovoltaic, SVPWM, CSI. I. INTRODUCTION In recent past years the photovoltaic (PV) systems have been received unprecedented concentration due to the raise of concerns about adverse effects of extensive use of fossil fuels on the environment and energy utilization with security in grid-connected PV systems that are still outnumbered by the power generation schemes which are based on oil or natural gas or coal or nuclear or hydro or wind or any combination of these [1] PV systems capacity is majorly based on the order of tens of megawatts that have been installed and interfaced at the grid level in the primary distribution where the PV system installation at the secondary distribution level are dominated by rooftop units with distinct capacities on the order of a few kilowatts with no significant impact on the existing power systems. Due to the growing interest in the usage of solar energy and adoption of national policies in favor of green energy where the emphasis is on significant increase in the number of large size PV plants which shows significant impact on the existing power grids that are ISSN: 2348 – 8379 expected as the two main components of a PV system which encompasses PV modules and power electronic inverters where the PV modules contribute to the overall cost of PV systems in a big way. A downward trend is clearly identified in the price per watt of PV modules due to substantial increase in the production of PV modules in different parts of the world the price of a PV module was USD per watt and the current market price is USD per watt where the practice in PV inverter mainly relies on voltagesource inverter (VSI) topology that normally requires another stage of power-electronic conversion for stepping up the voltage of the PV modules for a large-scale PV inverter which reduces the cost and improves the robustness and performance of powerelectronic grid interface which can further facilitate proliferation of PV systems in power systems. The current-source inverter (CSI) has the capability of becoming the most preferred topology for interfacing the PV system for the ac power grid due to following reasons. 1) The CSI provides a smooth dc-side current which is the most desirable feature of any PV module. 2) The energy storage element of a CSI has a larger lifetime than that of a VSI in implementation. 3) The CSI has an inherent voltage boosting capability that allows the integration of PV panels of lower output voltages and diminishes the requirements of the step-up interface transformer. 4) With the evolution of reverse-blocking (RB) in IGBT switches the series diodes will be eliminated due to which a justifiable reduction in the cost and conduction losses. 5) The recent advancements in super conductor technology leads us to the development of superconducting magnetic energy storage (SMES) systems that can considerably reduce the losses in the energy storage element of the CSI. II. RELATED WORK The diagram of the proposed three-phase with single stage grid connected PV system along with a CSI as the power conditioning unit is illustrated in Fig.1where the PV array is a parallel combination of np PV modules while each PV module is a series of combination of ns PV cells and the dc side inductor www.internationaljournalssrg.org Page 39 SSRG International Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – volume 1 Issue 9 –November 2014 Ldc filters out the ripples in the dc side current and allows its control where as the ac side of the inverter is interfaced with the primary side of the transformer Tr through a capacitive filter comprises of three Yconnected capacitors Cf which are tend to absorb the switching harmonics and to produce a clean sinusoidal current at the grid interface by including a breaker Bpv which is an integral part of the PV system and is provided to protect the PV system by isolating it when there is fault on the secondary side of the transformer Tr and the primary side of the transformer is delta connected whereas its secondary side is star connected with a solidly grounded neutral point where the resistance and inductance of the distribution line which is represented by Rg and Lg respectively Ps and Qs respectively represents the active and reactive powers that are supplied by the PV system to the distribution system where the breaker is part of the protection system installed by the utility. The control structure of the proposed solution for the CSI based PV system comprises of an outer current control loop that is designed to control the dc-side current and an inner current control loop which is responsible for controlling the current that is injected into the grid with a maximum power point tracker (MPPT) is installed to ensure that the PV array is operating at its maximum power range. Current input type PV module where in this paper we implemented the Current input type PV module in simulink for single PV module which is shown in below figure 6. Figure 6 Single PV Module implemented in Simulink Dlg Iabcpcc Figure 1 proposed three-phase single-stage grid connected PV system based on CSI. The PV array is connected to a distribution network with a voltage source converter (VSC) to analysis and control conveniently dq components in d-and-qaxis that are presented. III. SIMULATION RESULTS Simulation of PV System In the below figure 7 the PV array consists of six PV modules that are connected in series altogether by generating 133V dc voltage where the module can be implemented as voltage input type PV module or ISSN: 2348 – 8379 www.internationaljournalssrg.org Page 40 SSRG International Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – volume 1 Issue 9 –November 2014 Slg fault Vabpcc Tpg fault Vabcpcc Idc Idc Iabcs ISSN: 2348 – 8379 Iabccsi www.internationaljournalssrg.org Page 41 SSRG International Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – volume 1 Issue 9 –November 2014 Iabcpcc Iabccsi Ll fault Vabcpcc Iabcpcc Idc ISSN: 2348 – 8379 Pv64 fuzzy Isolation www.internationaljournalssrg.org Page 42 SSRG International Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – volume 1 Issue 9 –November 2014 Vabcpcc Iabcs Idc Iabcpcc Vabc,iabc Iabccsi ISSN: 2348 – 8379 www.internationaljournalssrg.org Page 43 SSRG International Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – volume 1 Issue 9 –November 2014 REFERENCES [1] M.Ciobotaru, T.Kerekes ,R.Teodorescu, A. Bouscayrol, “PV inverter simulation using MATLAB/Simulink graphical environment and PLECS blockset,” IEEE IECON 2006 Annual Conference on Industrial Electronics, pp. 5313-5318, Nov. 2006. [2] S. Oh, M. Sunwoo, “Variable structure PWM controller for high efficient PV inverters,” IEEE International Conference on Sustainable Energy Technologies, pp. 24-27, Nov. 2008. [3] J. P. Benner and L. Kazmerski, “Photovoltaics gaining greater visibility,” IEEE Spectr., vol. 36, no. 9, pp. 34–42, Sep. 1999. [4] Trends in Photovoltaic Application, Survey Report of Selected IEA Countries Between 1992 and 2002 International Energy Agency Photovoltaic Power System, IEA, Pvps t1-12:2003, 2003 [Online]. Available: www.iea-pvps.org [5] S.K. Chung, “A phase tracking system for three phase utility interface inverters,” IEEE Trans. Power Electron., vol. 15, no. 3, pp. 431–438, May 2000. [6] P.Vas, Vector Control of AC Machines. Oxford, U.K.: Oxford Univ.Press, 1990. Control ckt IV. CONCLUSION In this paper we proposed a system which is based on the grid connected PV system using MATLAB software where the maximum power point tracking (MPPT) and fault analysis are studied thoroughly where the control consists of a current control strategy that permits dc-link voltage regulation and enables power factor control and a voltage control strategy which significantly decouples dynamics of the PV system from those of the distribution network and loads and renders the PV system protected against the external faults and the other one is voltage control strategy which is capable of achieving the maximum power point tracking and maximization of the real power output of the PV system. ISSN: 2348 – 8379 www.internationaljournalssrg.org Page 44