The need to diversify power generation sources, increase security of supply, incorporate sustainability in energy sources and reducing fuel usage and emissions has significantly led to the integration of variable renewable energy sources such as wind to power grids globally. However, increased integration of wind power into a grid necessitates the need to update unit commitment and operating reserve algorithms since wind power is highly variable, intermittent and non-dispatchable. In addition, operational decisions in these grids are made on the basis of wind and load forecasts which are not perfect. Therefore, variability and uncertainty due to wind power introduced in the system requires an increase in operating reserve allocation to maintain reliability levels after wind power integration. This paper reviews recent work on determination of additional operating reserve requirement for power systems with large scale wind power integration. It also highlights different methods incorporated in solving the optimization problem in balancing between economics and reliability of power systems in sizing of additional reserve. In conclusion, gaps in literature that require further research are identified