Delta-Modulated AC–AC Converter for PM WECS

An ac-to-ac converter has been developed to convert the variable input frequency in wind energy conversion system (WECS) to a constant output frequency of 50 Hz for a distributed generation unit. The switching strategy and control mechanism for the converter is presented using time domain simulations in MATLAB environment. A specific triggering pattern has been generated for the switching devices in the converter to achieve desired polarity of the output voltage across the distributed load. The harmonics in the input supply side of the converter are mitigated by using delta modulation technique, whereas in the output of the converter, passive filtering has been used along with delta modulation technique. The design and implementation issues of the modulation technique and the switching scheme are discussed in detail with suitable simulation and experimental results. The analysis and properties of the proposed solution is compared with the known solutions. It has been concluded that an ac-ac converter is technically a viable option to interface a wind turbine to a utility grid.