Download
1 / 34
340 likes | 466 Views
EVALUATING THE POTENTIAL IMPACT OF TRANSMISSION CONSTRAINTS ON THE OPERATION OF A COMPETITIVE ELECTRICITY MARKET IN ILLINOIS. Tom Overbye Dept. of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Champaign, IL overbye@ece.uiuc.edu May 13, 2005. Overview.
E N D
EVALUATING THE POTENTIAL IMPACT OF TRANSMISSION CONSTRAINTS ON THE OPERATION OF A COMPETITIVE ELECTRICITY MARKET IN ILLINOIS Tom Overbye Dept. of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Champaign, IL overbye@ece.uiuc.edu May 13, 2005
Overview • Presentation summarizes results of UIUC portion of the project, which was done in close collaboration with ANL. • Goal was to do detailed security constrained optimal power flow (SCOPF) studies to assess the impact of transmission system constraints in the Illinois transmission grid • Studies were done using PowerWorld Simulator with SCOPF add-on
Security Constrained OPF • The SCOPF provides an “optimal” system dispatch that satisfies the base case and contingency constraints; can uses either the “ac” or “dc” power flow approach • used dc approach in this study • The bus locational marginal prices (LMPs) can then be directly determined from the SCOPF solution • the LMPs tell the incremental cost of supplying one more MWh to a bus
LP-based SCOPF • LP-based SCOPF used full contingency processing to determine the contingent violations, and then iterated between the power flow to take into account system non-linearities (phase shifter limits) and LP with linearized model to redispatch controls • an “outer loop” was used with SCOPF to resolve the contingencies with the optimized system
System Model • Model was constructed from 2003 summer peak power flow case, with utility modifications • original case contained about 42,700 buses • To reduce computation, a 12,925 bus, 1790 generator “equivalent” was created • equivalent covered region roughly bounded by Minnesota, Missouri, Tennessee, Ohio and Michigan • full Illinois system was included in the model
System Model, continued • In-state generator cost information was provided by ANL • Out-of-state generator cost information was determined by UIUC using a variety of sources • Fuel-costs were as provided by ANL • Hourly system load variation was as provided by ANL to be equal to assumed 2007 conditions • Phase shifters were allowed to vary in the SCOPF solution
Contingencies • Each solution enforced 1360 contingencies provided by the Illinois Utilities
Solution Overview • Initial SCOPFs were solved for each hour for the assumed 2007 conditions with the assumption that all generators submitted bids equal to marginal costs • data was calculated and stored for each bus for each hour hundreds of millions of numbers
Solution Problem • Results showed Illinois to be a net importer of power, which did not match historical data for recent • Potential reasons for this discrepancy • potentially inaccurate out-of-state cost estimates • potentially inaccurate fuel costs • insufficient model size (e.g., east coast markets were not included in the study)
Modified Solution • To access impact of interchange skew on results a second 2007 case was run with the out-of-state generator cost data increased slightly • this changed Illinois to being a net importer • While these changes did modify the results, they had little impact on the congestion regions
Interpretation of Results • A point to stress in understanding the results is the details matter. For example, whether a particular line was binding, and hence the cause of high LMPs in a region, was dependent upon many factors, including the line’s limit, the contingency set, and availability of post-contingent operating procedures
Interpretation of Results, cont. • It should also be stressed that there were LOTS of results. Hence trying to summarize the results was a major challenge!
Interpretation of Results, cont. • Key results were a listing of the binding constraints, and the resultant LMPs
Illinois Transmission System Congestion Regions: Second Case
Congestion Region Details • Details about each congestion region are included in the report • Example: Kankakee congestion region Due to congestion on blue Davis Creek 345/138 kV transformer for 345-L17704_R-S contingency (loss of red transformer and several other devices)
Profit Maximization • Profit maximization was studied at the 90% of peak load level, a level that would be reached about 80 hours per year • Profit maximization was tested by increasing generation bids at one or more generators, and then calculating the company’s revenue from its generators
Profit Maximization Results • The only companies found to have the ability to increase their revenue were Midwest Generation, Ameren CILCO and CWLP
Midwest Generation • One scenario is for the generators at Collins, Powerton and Waukegan to submit bids equal to marginal cost, and all others to submit bids equal to a multiplier times their marginal cost • Table on next page shows results
90% Load LMPs with Some Midwest Gen Bids 10 times Marginal Cost
Ameren CILCO • Scenario considered was Edwards generators submit bids equal to a multiplier times their marginal cost; all others submit marginal cost • This causes a binding constraint on the Tazwell-East Peoria 138 kV line (contingencies are loss of Duck Creek-Tazewell 345 kV or loss of Tazewell-Powerton 345 kV) • Results assume the upgrade of the Tazewll-E.Springfield 138 kV line
CWLP • If CWLP increased bids on all their plants eventually they would increase their revenue
Conclusion • For many loading conditions the Illinois transmission grid will have congestion, resulting in LMP variation • For certain loading conditions some companies could increase their revenue by submitting bids substantially above their marginal cost
