Monthly Archive for October, 2009

Data source: Texas Electric Reliability Council 2003-2008
In most of the time, there is only one price in spot Texas wholesale electricity market. For example, energy generated by wind power plants (get money) in remote west Texas is sold into the electricity grid at that price and can be consumed in energy-hungry metropolitan area like Houston paying that price. But like expressway may get congested when traffic is heavy, electricity transmission line can get congested as well. If congestion happens, Texas becomes four markets, i.e. spot wholesale electricity prices are different in North, South, West and Houston zones.
Below are some graphs showing when did congestion happen in the data.

1. It seems there is no seasonality in congestion frequency series. But it displays a big spike between March-May 2008.
   
2. Except in 2008, we see the highest probability of congestion happening around 12-13pm.