IOSR Journal of Computer Engineering (IOSR-JCE) e-ISSN: 2278-0661, p- ISSN: 2278-8727Volume 16, Issue 1, Ver. VII (Feb. 2014), PP 91-98 www.iosrjournals.org www.iosrjournals.org 92 | Page Charge Pump Phase Locked Loop Synchronization Technique in Grid Connected Solar Photovoltaic Systems K. N. Dinesh Babu 1 , R. Ramaprabha 2 , V. Rajini 3 , Kamal Bansal 4 1 (Research Scholar, Dept. of Power Systems, University of Petroleum & Energy Studies, India) 2 (Associate Prof., Dept. of EEE, SSN College of Engineering,, India) 3 (Prof., Dept. of EEE, SSN College of Engineering,, India) 4 (Prof., Dept. of Power Systems, University of Petroleum & Energy Studies, India) Abstract : In this paper, an attempt to design and simulate charge pump phase locked loop method of synchronization in grid connected solar photovoltaic system has been made. Delivery of power with high quality to the grid is of concern in grid connected systems and to ensure the same auto synchronization technique is required. Such a method is proposed and analyzed using MatLab-Simulink and its performance is verified for compliance with IEEE 929 standard prescribed for inverter fed grid systems and IEC 61727 / IEEE 1547 standard for harmonic limitation of grid connected inverters. Keywords: Charge Pump Phase locked loop, IEC 61727, IEEE 929, IEEE 1547, MatLab, Solar photovoltaic array, Synchronization I. INTRODUCTION Increasing demand in power sector has resulted in need for renewable energy sources. Solar power generation has several advantages mentioned in literature [1] and hence synchronization of the solar photovoltaic (SPV) system output to the grid is mandatory. Several issues pertaining to grid connected inverters have been discussed [2] and resolution of these issues is mandatory for proper functioning of grid integrated system. The challenges in synchronization involves magnitude, frequency and phase angle of the voltage at the point of common coupling (PCC) and these parameters produced from the SPV system has to be matched. In this paper the charge pump phase locked loop (CP-PLL) method has been used to meet the above mentioned requirements. Design and working principle of CP-PLL technique is discussed in detail in literature [3]. Auto synchronization technique is the process of following the phase angle and frequency of the grid voltage after synchronization [4]. Auto synchronization is often challenged with harmonics, system disturbance and load variations. The limits beyond which the grid interactive inverters would be islanded are mentioned in IEEE 929 standard. Harmonic limits for 10 kW and 30 kW systems are specified in IEC 61727 and IEEE 1547 standard respectively [5], [6]. In this paper, CP-PLL technique has been tested subject to various scenarios that are likely to occur in a grid. The response of this technique is compared with limits mentioned in standard. The compliance of the results with IEEE 929, IEC 61727 and IEEE 1547 standards are also presented. II. DESCRIPTION OF THE PROPOSED SYSTEM The proposed CP-PLL synchronization technique for grid connected SPV system is illustrated in Fig. 1. The application of CP-PLL control technique is used here to address the issues discussed in the previous section failing which the power quality and synchronization would be affected. The inverter pulse firing pattern is adjusted based on the grid reference and this modification is implemented using CP-PLL which is described in Fig. 1. The SPV system feeds the grid with a control technique to maintain synchronization. Inverter firing is based on the comparison of modulating signal and carrier signal [7]. The pulse width modulation (PWM) depends on the modulating signal quality. The PCC voltage is taken as reference and the PWM pulses are generated based on modulating signal using CP-PLL technique. The schematic diagram of the proposed CP-PLL is described using Fig. 2. A balanced three phase symmetrical voltage is assumed in CP-PLL design technique [6].