Wind Energy Demand for Transmission Capacity

It may be to cover the peaks of generation with regard to the base loading. Can't think of any other reason.

I think you are right since it seems illogical that the production style decides the capacity of transmission .

Wind power sources are highly variable and unlikely to be in sync with peak demand. Large swings in production and demand will require larger distribution infrastructure that can reliably handle the variable conditions. Grid storage sources, like pump storage hydro which could mitigate the variability, are few and far between and are not likely to significantly grow due to NIMBY and environmental disturbance resistance.

All transmission and distribution network elements must always be sized for the peak power flow conditions [actually currents are used rather than power as basis for sizing conductors].

Other than wind mill generation, even other type of generation may not continuously operate at peak generation capacity. The grid loads usually vary from peak to light load conditions but the system will be designed to carry peak loads with operating strategies under various load conditions, including contingency conditions.

The contingency conditions are also considered in planning and designing the transmission / distribution systems.

Load flow studies is one of the most commonly used tool in determining various parameters of transmission/ distribution systems.

I think the OP misunderstands what was being compared when he asks about the grid needing higher capacity than what. For wind energy in comparison to other energy sources, the transmission system does not need to be higher capacity. As other posts have said, the grid needs to have the capacity for peak flows, whether it comes from wind, coal, nuclear, etc.

Where this issue comes into play is when wind generation is added to the existing transmission system with no corresponding increase in transmission capacity. This is the case in many regions of the US, where there are government tax incentives for development of wind generation facilities, but no associated incentives for the transmission infrastructure to be upgraded. Some areas in my state have many megawatts of wind generation proposed, but no plans to increase the number and capacity of transmission lines out of those areas to the load centers. Since wind farms are often built far from the largest loads, you have to transport the power somehow, but when the wind blows (and ALL of the generators want to sell their wind-generated MW!), there isn't enough transmission capacity to get it all to market.

That doesn't even address the question of how to handle base-loading with a source as inconsistent as wind without some means of energy storage, but that's the stuff of a different discussion.

An interesting article in the UK press last year claimed that wind farms were being paid by the generating companies not to generate. The generators have to maintain a spinning reserve, the last thing they want is the odd gust of wind forcing them to absorb power they don't want or need.

sorry but I didnt misunderstand what I read since it was in my native language and was saying clearly that wind energy plants necessitates higher transmission capacities than other types of plants. I agree with all of you also as I stated above...