DC-Link Voltage Regulation of Full-Power Converter for WECS in Weak-Grid Using a Variable-flux Dual-Stator PMSG

Abstract

Wind Energy Conversion Systems (WECS) in weak-grid and stand-alone modes suffer from voltage and frequency fluctuations due to wind speed or/and load variations. However, it is needed to regulate output voltage before supplying to grid/load. Thus, generator output is rectified and then inverted to constant voltage and frequency before supplying to load. In standard configurations, rectifier and inverter both use controlled switches. Therefore, full control over the output voltage is achieved however, higher no. of electronic switches with their complex control circuitry and use of mechanical sensors jeopardizes reliability of the system. This paper proposes a WECS that uses half the no. of controlled switches with simpler control circuitry. It is to be noted that no mechanical sensors had been used in sensing the wind speed. The proposed system consists of a variable-flux dual-stator permanent magnet synchronous generator with an uncontrolled rectifier and an inverter working at constant modulation indexes. A proof-of-concept generator had been fabricated and tested under simulated wind conditions. The generator was tested for voltage regulation under two conditions. First under variable wind speed and constant load (VWCL) and second under constant wind speed and variable load (CWVL). It was observed from results that in proposed system the generator regulates its output voltage and power invariant to variable input wind speed and variable load.