An Improved Multi-Functional Scheme for Grid Interfaced PV Energy Conversion System

This paper proposes an improved Phase Locked Loop (PLL) based synchronization method for integrating Solar Photovoltaic (SPV) energy in to the grid, in a three phase distribution system with all types of load connected at Point of Common Coupling (PCC). This PLL is immune to the signals unbalancing. It estimates frequency, magnitude and phase of the input load current and gives a filtered output. The main challenge in the power converter synchronization is the fast and accurate detection of the fundamental component from the polluted load current. An accurate phase angle ensures decent control of grid interfaced converter which is used to interface SPV energy to the grid. The proposed system feeds the maximum extracted PV power and takes care of various Power Quality (PQ) problems such as harmonics suppression, Power Factor Correction (PFC) and load balancing. It also determines accurate phase angle to synchronize and distortion free signals etc. The detailed stability analyses of the proposed PLL are carried in terms of frequency response and Routh Hurbitz criterion to predict the system dynamics. These stability analyses are compared with other conventional PLL in order to establish the supremacy of proposed PLL over other. Test results validates the above claims.