Identification of Suitable PLL Technique for Grid-Connected PV System

In the entire grid-connected renewable power plant applications, synchronizing the output signals of the convertors and inverters that are connected with grid parameters like voltage, current phase, and frequency are of utmost importance. When we talk about the power system networks harmonics, distortion and reactive power generation are the most important factors leading to the loss of power in the transmission lines [1]. To meet the requirements that are demanding to the grid interconnections with renewable energy harvesting plants, the necessity is to improve the control over the power generation Systems, the techniques to control them include current and the voltage control of the photovoltaic inverter which are linked to the grid. In the grid-connected modes, the parameters like frequency and amplitude of the photovoltaic inverter voltages and those which operate in the current-controlled mode are controlled by the grids. The current controller which is linked to the power system networks to the grid-connected modes basically achieves two important conditions which are—(a) During the light load conditions in an area, the energy which is excess is obtained from the PV inverters which needs to be fed back again to the grids. (b) During the overload conditions and during the non-favorable atmospheric conditions, the demands of the load can be met with both the grid and the PV inverters [2]. The algorithms of the grid synchronization have a significant function toward the distributed power generation systems (DPGS). This paper shows the various methods of synchronization which use the techniques of phase lock loop (PLL) and the different types of methods of synchronizing the grids using the techniques of phase-locked loops. The synchronization with the signals in the grid is generally performed in accordance with the parameters like frequency, voltage, and phase angles of current signals and voltage signals of the systems. This paper presents the PLL parameter’s selection method for voltage grid conditions and presents an analysis on the developed phase-locked loop techniques that are being used recently to improve the performances of the grid and a comparative analysis among them based on the various parameters [3].