X hits on this document

692 views

0 shares

0 downloads

0 comments

123 / 179

2009 State of the Market Report

Transmission Congestion

Figure 59: Pricing of Unmanageable Congestion by Voltage Level 2009

300

42%

250

33%

200

Binding Hours

150

100

11%

12%

23%

22%

23%

19%

29%

15%

20%

22%

14%

50

7%

8%

9%

16%

20%

28% 26%

0

0 0-30 30-60 60-90 90+ 0 0-30 30-60 60-90 90+ 0 0-30 30-60 60-90 90+ 0 0-30 30-60 60-90 90+

69-115kV

138kV 161-230kV Shadow Price as Percent of Marginal Value Limit

345kV

Only 8 percent to 26 percent of violated constraints (depending on voltage level) are priced within 90 percent of the MVLs. Additionally, it shows that on all but the highest-voltage constraints, a substantial share of the violated constraints are priced at a zero shadow price, indicating that the LMPs include no reflection of the violated constraint. For example, 42 percent of the violated low-voltage constraints had a shadow price equal to zero. This raises substantial concerns regarding the efficiency of the LMPs under these conditions.

The reason the shadow prices can be far less than the MVL is that the Midwest ISO uses a constraint relaxation algorithm that essentially raises the limit for the constraint to allow the real- time market to achieve a feasible solution. The results above suggest that the algorithm often produces inefficient shadow prices that distort the associated LMPs and understates the reliability cost of violating the constraint. Hence, we continue to recommend that the Midwest ISO discontinue use of the relaxation algorithm and set prices based on the constraint penalty factors.

Page 90

Document info
Document views692
Page views692
Page last viewedThu Dec 08 06:35:46 UTC 2016
Pages179
Paragraphs5369
Words52656

Comments