Synchronization algorithms for grid-connected renewable systems: Overview, tests and comparative analysis

This paper presents five synchronization algorithms that are commonly used in grid-connected renewable systems. The algorithm structures are studied and their corresponding block diagrams are shown and explained in detail. The behaviors of the algorithms are studied according of their response under voltage unbalances, frequency variations and low-order voltage harmonics. The advantages and disadvantages of the algorithms are discussed by analyzing some simulations done with MATLAB/SIMULINK tool from The MathWorks, Inc. Later on, the final validation is done by doing real-time digital tests of the synchronization algorithms with a Real-Time Digital Simulator (RTDS) platform. A grid-connected photovoltaic system with a nominal power of 10 kW is used to evaluate the responses of the synchronization algorithms when the utility grid is affected by disturbances.