Ramp rate modeling for ERCOT look ahead SCED

Required by NPRR 351, starting June 28, 2012, ERCOT begins to post indicative real time market prices for future intervals. The indicative real time LMP's are calculated by a separated market application, which optimizes over the next hour based on forecasted load demand and wind generation. To explicitly model ramp rate constraints, the optimization model becomes a Mixed Integer Quadratic Programming (MIQP) problem, which imposes a major performance challenge. This paper discusses the measures have been taken during implementation to meet the real time performance requirement.