Solving the ISO Seams Problem for Uniform Boundary LMP's
Thursday, December 5, 2002 - 10:40am - 11:30am
Bruce Wollenberg (University of Minnesota, Twin Cities)
The US Department of Energy, Federal Energy Regulators Commission, has released a Standard Market Design (SMD) which introduces the problem of enabling two Independent System Operators (ISO's) which independently calculate the market clearing prices for their respective markets to reach consistent Locational Marginal Prices (LMP's) along a shared boundary. Without consistent LMP's trading across a boundary (seam) can be difficult or impossible. This presentation will focus on the issue of enabling two ISO's to reach a common set of LMP's on the boundary. William Hogan has presented some preliminary work toward a solution wherein multiple ISO's solutions are iterated until a common solution is reached. In Hogan's work, only transmission limit constraints were imposed on the solution. We have extended this to include first contingency constraints as well. The market clearing calculations are done with an Optimal Power Flow (OPF) based on a full Alternating Current model of the power system. The LMP's are the bus power constraint Lagrange multipliers from the solution. Both Hogan's and our own work so far have been with linear networks not with full AC OPF solutions and full AC contingency analysis. The talk will explore many of the difficulties of achieving a common boundary bus LMP when each ISO is using an AC OPF and AC contingency analysis to calculate the LMP's and what research directions we see as promising. The aim of the work we are conducting is to achieve tools for ISO's to enable them to continue to operate independently yet to have uniform LMP's along the boundaries with other ISO's.