Market Performance and Planning Forum (examples) March 23, 2011 - - PowerPoint PPT Presentation

Market Performance and Planning Forum (examples)

March 23, 2011

How Would Flexible Ramping Constraint Affect LMP?

Slide 2

• Partially loading 2 generators where 1 alone would seem to be

sufficient.

• Two generators in the market to fill a 100MW load.
• Assume each generator has a range of 40-105 and one has a cost of

$30 while the other has a cost of $35

• Without any flexible ramping constraints the solution would be for the

$30 generator to fill the 100MWs by itself.

• With the flexible ramping constraint that each would be dispatched;

presumably the $35 unit would be dispatched to 40 while the cheaper

• ne would be dispatched to 60.
• Are the LMPs of each generator correct?

Example 1

• Flexi-Ramp constraint enforced in RTPD.
• Forecast Load: 100MW
• Forecast uncertainty (Flexible ramp req.): +50MW
• Resources Available
• Unit 1: Pmin=40MW, Pmax=105MW, Energy Bid=$30
• Unit 2: Pmin=40MW, Pmax=105MW, Energy Bid=$35
• The following two constraints are enforced:

– ENgen-ENload = 0 (Power balance constraint Ignoring losses) – FRonlinegen-up >= FRreq-up (Flexi-ramp constraint)

Page 3

Example 1 (cont.)

• Without Flexi-ramp Constraint:

– Unit 1: Committed and loaded to 100MW at price of $30 – Unit 2: Remains Un-committed

• With Flexi-ramp Constraint enforced in RTPD:

– Unit 1: Committed and loaded to 60MW at price of $30

• Contributing 45MW of online capacity to Flexi-ramp

constraint – Unit 2: Committed at Pmin= 40MW

• Contributing 5MW of online capacity to Flexi-ramp constraint
• Note the energy prices in RTPD are not binding. Only

RTD prices are binding.

Page 4

Example 1 (cont.)

• In RTD binding interval no flexi-ramp constraint is

enforced.

• Assuming actual load in RTD is 100MW

– Unit 1: Dispatched to 60MW at a marginal price of $30 – Unit 2: Dispatched to 40MW at a marginal price of $30

• Assuming actual load in RTD is 150MW

– Unit 1: Dispatched to 105MW at a marginal price of $35 – Unit 2: Dispatched to 45MW at marginal price of $35

Page 5

Example 2

Page 6

• Flexi-Ramp constraint enforced in RTPD.
• Forecast Load: 100MW
• Forecast uncertainty (Flexible ramp req.): +100 MW
• Resources Available
• Unit 1: Pmin=40MW, Pmax=105MW, Energy Bid=$30
• Unit 2: Pmin=40MW, Pmax=105MW, Energy Bid=$35
• The following two constraints are enforced:

– ENgen-ENload = 0 (Power balance constraint Ignoring losses) – FRonlinegen-up >= FRreq-up (Flexi-ramp constraint)

Example 2 (cont.)

Slide 7

• Without Flexi-ramp Constraint:

– Unit 1: Committed and loaded to 100MW at price of $30 – Unit 2: Remains Un-committed

• With Flexi-ramp Constraint enforced in RTPD:

– Unit 1: Committed and loaded to 60MW at price of $30

• Contributing 45MW of online capacity to Flexi-ramp

constraint – Unit 2: Committed at Pmin= 40MW

• Contributing 55MW of online capacity to Flexi-ramp

constraint

• Note the energy prices in RTPD are not binding. Only

RTD prices are binding.

Example 2 (cont.)

Slide 8

• In RTD binding interval no flexi-ramp constraint is

enforced.

• Assuming actual load in RTD is 100MW

– Unit 1: Dispatched to 60MW at a marginal price of $30 – Unit 2: Dispatched to 40MW at a marginal price of $30

• Assuming actual load in RTD is 200MW

– Unit 1: Dispatched to 105MW at a marginal price of $35 – Unit 2: Dispatched to 95MW at marginal price of $35