Modeling and control of 1.5 MW rated sparse matrix converter based wind energy conversion system

Sparse matrix converter (SMC) is a matrix converter topology without any storage element like an inductor or a capacitor. There is a fictitious DC link between rectifier and inverter stages in SMC topology. The input is directly connected to the output via a set of bidirectional power semiconductor switches. Such an arrangement decreases the converter size and increases the reliability. Due to these advantages, SMC is used in many applications like AC drives, aerospace industry, electric ships, as well as in wind energy applications. In this thesis, a three-phase SMC is adapted to a grid-connected permanent magnet synchronous generator-based wind energy conversion system (WECS). The IGBT is chosen as the power semiconductor element in the rectifier and inverter stages, controlled by sinusoidal pulse width modulation technique. The switching frequency is changeable in the range between 20-50 kHz. The overall system including the power stage as well as the control sub system are modelled and tested under various operating conditions. An LCL filter is replaced at the output of the SMC to weaken switching harmonics. Moreover, a fuzzy fractional-order PID (FFOPID) controller is designed to control active and reactive power of WECS. By this way, the dynamic response of a classical PID controller with fixed gains is improved by combining the salient features of fractional-order calculus and fuzzy logic theory. The simulation results show that the designed FFOPID controller is superior to classical PID controller in tracking d- and q-axis current references of the SMC at the output. FFOPID controller shows better transient performance when unit step changes are applied to the reference signals.