Wind Power Capacity Value in the Philippines

Prof. Rowaldo Del Mundo, my respected professor in UP-Diliman, came out with the study of quantifying the value of wind power in terms of capacity last year. I believe this is welcome advancement in understanding the contribution of wind energy in the country. As investments in renewable energy sources are coming in, studies like this are sure to support the anticipated technical and economic impacts of integrating wind power into the grid.

However, just as I was taught by the good professor, there are some loopholes in the study I thought needing some discussion thereof.

First, the study considered wind power plants to have an equivalent forced outage rate (EFOR). Forced outage rate (FOR)  is computed using the mean time to failure and the mean time to repair of a component of a generating plant to be in service or not. The Philippine Grid Code defines FOR as:

From this premise, FOR is a component based value not a fuel availability based variable. Wind power is variable. A wind farm stops to produce power when wind stops blowing, not mainly because a component in the wind farm fails.

An accepted approach to overcome the FOR modeling of a wind farm is to model the wind power output as a negative load. Studies here and here by IEEE and NERC uses this practical strategy since load is variable and adding wind power increases the variability is the power system. With this, you don't have to assume an EFOR for electrical or mechanical components inside the wind farm since they don't really fail, its just that the wind is not blowing.

Second, the study's conclusion includes this: The maximum penetration limit is, at the end not a technical issue, it is an economic issue that must  be resolved based on willingness to pay of the consumers.

I remember that when the 1216MW Sual power plant suffered failure and resulted to a Luzon wide blackout. Imagine the peak load of Luzon as about 6500MW, the capacity output of Sual is 25% of that loading condition. Which gives us a scenario that a plant generating 25% of the demand level provides risk in the system operational reliability. If wind power penetration becomes 25% of any demand level, we are merely replicating the possibility of what happened in 2001 since wind is variable. The integration of any energy resource in any grid would always be a technical issue. That is why Prof. Del Mundo was part of the team who they developed the Grid Code and the Distribution Code.

A single study must not generalize such conclusion without looking at all angles and involving all stakeholders.

Third, the study cites that the capacity value of wind in the Luzon grid is nil. Zero. Nada. This is surprising. Any resource adds capacity. Any amount of energy resource penetration level adds value. Below is a figure from this IEEE study.

 

The figure above tells us that there is a certain capacity value relative to a certain amount of wind power penetration in various electric transmission systems. I am wondering what is very unique in the Philippine electric power systems to have wind power assessed as having no capacity value when added to the grid.  

Wind power will play an important role in the energy situation in our country though it is variable in nature. It will add resource and capacity together with conventional plants, much needed as demand grows. We must study its impact carefully.