Frequency Control and Virtual Inertia Emulation Techniques for Grid Connected Wind Energy Conversion Systems - A Review

Onshore and offshore wind power generation continue to grow rapidly around the world due to their increasingly competitive prices. Wind turbines in modern wind energy conversion systems are decoupled from the AC grid through power electronic converter interfaces. This results in little or no inertia from these sources from the grid point of view. As a result, high level penetration of wind energy and other converter based renewable energy sources in electricity grids result in reduction of total system inertia thus affecting frequency stability in such systems. In order to mitigate against this phenomenon, a number of inertia emulation and frequency control techniques have been proposed to enable wind energy conversion systems participate in frequency regulation in power grids. This paper reviews the existing inertia emulation and frequency control techniques for grid connected wind energy conversion systems and gives recommendations on future research directions in this field.