Current limitation for the machine side converter of permanent magnet synchronous generator wind turbines during grid faults

Preservation of wind turbines (WTs) grid-connectivity during grid faults and grid-code (GC) compliant reactive power injection at PCC during voltage drops is an imperative task to perform in modern WTs. This is known as the low-voltage ride-through (LVRT) capability of WTs, emerging as an integral GC requirement. Despite current provision of LVRT in PMSG-based WTs, there is still likelihood of grid voltage drops leading to adverse effects in wind power plants. In this research, a peak current limiter has been designed for machine-side converter (MSC) of the PMSG-based WT to execute GC requirements in a reliable manner. This scheme is capable of preventing over-voltage across the dc link of back-to-back (BTB) converter and over-current in the grid-side converter (GSC). A dual current controller is utilised for regulating GSC positive-and negative-sequence components. A prominent feature of the proposed controller is its simplicity and applicability to available BTB control systems. On the other hand, the WT mechanical system operates as a storage device during voltage drops, eliminating the need for installing external apparatus such as energy storage systems and braking choppers across the dc-link. Simulation results conclude the reliable operation of the WT equipped with MSC current limitation scheme during grid faults.