Synchronizing renewable energy sources in distributed generation systems

Abstract

In renewable and distributed generation systems the grid voltage quality can be poor. So, the connection of power converters to the grid requires accurate control of synchronism between the two sources. The paper discusses issues on synchronization of power converters connected to the mains and related control methods. The design and experimentation of a prototype of a 200 kW power converter that connects a wind generator to the grid help to validate the adopted approach. In this paper a new zero crossing synchroniser is proposed having zero error in steady state, moderate speed response to grid frequency changes and amplitude voltage variations, and harmonics and noise immunity. The speed response, and harmonics and noise immunity are a trade-off. Simulation results with strong disturbances in the grid voltage show the robustness of the proposed method.