Synchronous generator based wind energy conversion system (WECS) using multi-modular converters with autonomous controllers

Among various options available for wind energy conversion systems, this paper focuses on direct driven Synchronous Generator (SG) based variable speed wind turbine (VSWT). Generally SG is connected to the power grid via full-size power converters. But with the growing trend of multi mega watt turbine installation, the idea of modular- converter units is gaining popularity. Multi-module topology has proven its supremacy in terms of reliability, efficiency and harmonic reduction over its medium voltage full rating converter counterpart. Research conducted earlier on modular converter system either had a centralized control structure or was in master/slave configuration. This paper explores the option of autonomous controller for modular converter system. One of the main challenges faced in design of autonomous controller is to ensure equal power sharing among the operating units without employing any communication between them. Also in order to enhance system harmonic performance, control structure should enable interleaving of operational units under all conditions. Such an autonomous controller will greatly improve system reliability/redundancy. To test the developed autonomous controller, simulation is carried out using MATLAB.