Re: Question about LMP

[Kanis Kanis]

Dear all,

I would like to ask something more about LMPs. Is there any function 
like DCOPF that incorporates the impact of losses in
the calculation of LMPs, like the models (that are now applied in PJM, 
NYISO etc.) which explicitly balance the losses in the energy balance 
equation?


Thank for your comments.

Regards Gregory.




On 11/19/2015 6:12 AM, Jovan Ilic wrote:


Dear Victor,

If there is no congestion in the network, there is the same LMP at all 
the nodes.

The LMP consists of loss, congestion, and energy costs. DCOPF has no
losses, and if there is no congestion only the energy cost is 
accounted for.
You can think of it as if since there is no congestion or loss cost 
the energy can

be distributed to all nodes at the same price.

Regards,
Jovan Ilic

On Wed, Nov 18, 2015 at 4:37 PM, Victor Hugo Hinojosa M. 
mailto:victor.hinoj...@usm.cl>> wrote:


Dear Prof. Zimmerman,

I have a question about Local Marginal Prices (LMP) that are shown in
Matpower.

The definition of the LMP is the marginal cost of supplying, at
least cost,
the next increment of electric demand at a specific location
(node) on the
electric power network, taking into account both supply
(generation/import)
bids and demand (load/export) offers and the physical aspects of the
transmission system including transmission and other operational
constraints.

When it is performed a DCOPF, Matpower shows LMP for each bus
considering
the marginal cost (energy cost) and the congestion cost so that
I'd like to
know why the generation constraints (maximum and minimum power) aren't
considered in the LMP.

Thank you so much for your ideas and comments.

Regards,

Vh







---
This email has been checked for viruses by Avast antivirus software.
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RE: Question about LMP

[Victor Hugo Hinojosa M.]

Dear Jovan and Sarmad,

I agree with your comments about LMP. In this analysis I’m not considered the 
congestion. If the generation inequality constraints aren’t active, Matpower 
prints this information correctly, and It’s possible to realize different 
prices when the lines is congested. Sarmad, I’ve verified your idea. Despite 
the fact that the shadow price for the minimum or maximum is active, the LMP 
shown are the same for all buses. 

My question is about why LMP doesn’t include the Lagrange multipliers related 
to generation inequality constraints. I did a model using the dual problem for 
the DCOPF, and I realized that dual constraints are the prices for each buses. 
It’s very clear in those constraints that those “prices” take into account the 
marginal cost, the congestion cost through the partial transmission 
distribution factors (PTDF) and the generation constraints. 

In the technical literature for the DCOPF (losses are neglected), the LPM are 
modeled considering energy cost and congestion cost. However, in the book “Spot 
pricing of electricity” from F. Schweppe et all, authors include these shadow 
prices in order to compute the spot prices.

I’d like to know your feedback about these comments.

Regards,

Vh

 

De: bounce-119912654-12657...@list.cornell.edu 
[mailto:bounce-119912654-12657...@list.cornell.edu] En nombre de Jovan Ilic
Enviado el: jueves, 19 de noviembre de 2015 1:13
Para: MATPOWER discussion forum
Asunto: Re: Question about LMP

 

 

Dear Victor,

 

If there is no congestion in the network, there is the same LMP at all the 
nodes. 

The LMP consists of loss, congestion, and energy costs. DCOPF has no 

losses, and if there is no congestion only the energy cost is accounted for. 

You can think of it as if since there is no congestion or loss cost the energy 
can

be distributed to all nodes at the same price. 

 

Regards, 

Jovan Ilic

 

On Wed, Nov 18, 2015 at 4:37 PM, Victor Hugo Hinojosa M. 
 wrote:

Dear Prof. Zimmerman,

I have a question about Local Marginal Prices (LMP) that are shown in
Matpower.

The definition of the LMP is the marginal cost of supplying, at least cost,
the next increment of electric demand at a specific location (node) on the
electric power network, taking into account both supply (generation/import)
bids and demand (load/export) offers and the physical aspects of the
transmission system including transmission and other operational
constraints.

When it is performed a DCOPF, Matpower shows LMP for each bus considering
the marginal cost (energy cost) and the congestion cost so that I'd like to
know why the generation constraints (maximum and minimum power) aren't
considered in the LMP.

Thank you so much for your ideas and comments.

Regards,

Vh



 

Re: Question about LMP

[Ray Zimmerman]

The LMPs for a DC OPF problem do incorporate any generator limits as well as 
generation cost. Consider the case with no congestion, where the LMPs are 
uniform at all nodes. For nodes with generators that are dispatched between 
their lower and upper limits, the LMP equals their marginal cost of generation. 
For a node with a generator at a binding upper (lower) limit, the LMP will 
equal the marginal cost of generation plus (minus) the shadow price on the 
binding upper (lower) generation constraint.

   Ray

> On Nov 19, 2015, at 8:27 AM, Victor Hugo Hinojosa M.  
> wrote:
> 
> Dear Jovan and Sarmad,
> I agree with your comments about LMP. In this analysis I’m not considered the 
> congestion. If the generation inequality constraints aren’t active, Matpower 
> prints this information correctly, and It’s possible to realize different 
> prices when the lines is congested. Sarmad, I’ve verified your idea. Despite 
> the fact that the shadow price for the minimum or maximum is active, the LMP 
> shown are the same for all buses.
> My question is about why LMP doesn’t include the Lagrange multipliers related 
> to generation inequality constraints. I did a model using the dual problem 
> for the DCOPF, and I realized that dual constraints are the prices for each 
> buses. It’s very clear in those constraints that those “prices” take into 
> account the marginal cost, the congestion cost through the partial 
> transmission distribution factors (PTDF) and the generation constraints.
> In the technical literature for the DCOPF (losses are neglected), the LPM are 
> modeled considering energy cost and congestion cost. However, in the book 
> “Spot pricing of electricity” from F. Schweppe et all, authors include these 
> shadow prices in order to compute the spot prices.
> I’d like to know your feedback about these comments.
> Regards,
> Vh
>  
> De: bounce-119912654-12657...@list.cornell.edu 
> [mailto:bounce-119912654-12657...@list.cornell.edu] En nombre de Jovan Ilic
> Enviado el: jueves, 19 de noviembre de 2015 1:13
> Para: MATPOWER discussion forum
> Asunto: Re: Question about LMP
>  
>  
> Dear Victor,
>  
> If there is no congestion in the network, there is the same LMP at all the 
> nodes. 
> The LMP consists of loss, congestion, and energy costs. DCOPF has no 
> losses, and if there is no congestion only the energy cost is accounted for. 
> You can think of it as if since there is no congestion or loss cost the 
> energy can
> be distributed to all nodes at the same price. 
>  
> Regards, 
> Jovan Ilic
>  
> On Wed, Nov 18, 2015 at 4:37 PM, Victor Hugo Hinojosa M. 
> mailto:victor.hinoj...@usm.cl>> wrote:
> Dear Prof. Zimmerman,
> 
> I have a question about Local Marginal Prices (LMP) that are shown in
> Matpower.
> 
> The definition of the LMP is the marginal cost of supplying, at least cost,
> the next increment of electric demand at a specific location (node) on the
> electric power network, taking into account both supply (generation/import)
> bids and demand (load/export) offers and the physical aspects of the
> transmission system including transmission and other operational
> constraints.
> 
> When it is performed a DCOPF, Matpower shows LMP for each bus considering
> the marginal cost (energy cost) and the congestion cost so that I'd like to
> know why the generation constraints (maximum and minimum power) aren't
> considered in the LMP.
> 
> Thank you so much for your ideas and comments.
> 
> Regards,
> 
> Vh
> 
> 
>  

Re: Question about LMP

[Ray Zimmerman]

I think your question is whether MATPOWER includes a solver for a DCOPF with 
losses. The answer is that currently it does not.

   Ray


> On Nov 19, 2015, at 4:55 AM, Kanis Kanis  wrote:
> 
> Dear all,
> 
> I would like to ask something more about LMPs. Is there any function like 
> DCOPF that incorporates the impact of losses in 
> the calculation of LMPs, like the models (that are now applied in PJM, NYISO 
> etc.) which explicitly balance the losses in the energy balance equation?
> 
> Thank for your comments.
> 
> Regards Gregory.
> 
> 
> 
> 
> On 11/19/2015 6:12 AM, Jovan Ilic wrote:
>> 
>> Dear Victor,
>> 
>> If there is no congestion in the network, there is the same LMP at all the 
>> nodes. 
>> The LMP consists of loss, congestion, and energy costs. DCOPF has no 
>> losses, and if there is no congestion only the energy cost is accounted for. 
>> You can think of it as if since there is no congestion or loss cost the 
>> energy can
>> be distributed to all nodes at the same price. 
>> 
>> Regards, 
>> Jovan Ilic
>> 
>> On Wed, Nov 18, 2015 at 4:37 PM, Victor Hugo Hinojosa M. < 
>> victor.hinoj...@usm.cl 
>> > wrote:
>> Dear Prof. Zimmerman,
>> 
>> I have a question about Local Marginal Prices (LMP) that are shown in
>> Matpower.
>> 
>> The definition of the LMP is the marginal cost of supplying, at least cost,
>> the next increment of electric demand at a specific location (node) on the
>> electric power network, taking into account both supply (generation/import)
>> bids and demand (load/export) offers and the physical aspects of the
>> transmission system including transmission and other operational
>> constraints.
>> 
>> When it is performed a DCOPF, Matpower shows LMP for each bus considering
>> the marginal cost (energy cost) and the congestion cost so that I'd like to
>> know why the generation constraints (maximum and minimum power) aren't
>> considered in the LMP.
>> 
>> Thank you so much for your ideas and comments.
>> 
>> Regards,
>> 
>> Vh
>> 
>> 
>> 
> 
> 
> 
>      
> This email has been checked for viruses by Avast antivirus software. 
> www.avast.com 

RE: Question about LMP

[Victor Hugo Hinojosa M.]

Thank you so much for the information Prof. Zimmerman.

I’d like your explanation about the simulation for the 6-bus system (Wood & 
Wollemberg). When I run a DCOPF with the original case (rundcopf(case6ww)), the 
LMP shown for Matpower are the same (11.899 $/MWh) for all buses because there 
isn’t congestion in the transmission lines. Despite of the fact that the 
Lagrange multiplier for generator 1 is active (0.303 $/MWh), the LMP are the 
same. In my opinion, the LPM from bus 1 should be 12.202 $/MWh.

I’ll wait for your comments.

Regards,

Vh

 

 

MATPOWER Version 5.1, 20-Mar-2015 -- DC Optimal Power Flow

Gurobi Version 6.0.4 -- automatic QP solver

 

Converged in 0.16 seconds

Objective Function Value = 3046.41 $/hr



| System Summary   |



 

How many?How much?  P (MW)Q (MVAr)

----  -  -

Buses  6 Total Gen Capacity 530.0   0.0 to 0.0

Generators 3 On-line Capacity   530.0   0.0 to 0.0

Committed Gens 3 Generation (actual)210.0   0.0

Loads  3 Load   210.0   0.0

  Fixed3   Fixed210.0   0.0

  Dispatchable 0   Dispatchable  -0.0 of -0.0  -0.0

Shunts 0 Shunt (inj) -0.0   0.0

Branches  11 Losses (I^2 * Z) 0.00  0.00

Transformers   0 Branch Charging (inj) -0.0

Inter-ties 0 Total Inter-tie Flow 0.0   0.0

Areas  1

 

  Minimum  Maximum

 -  

Voltage Magnitude   1.000 p.u. @ bus 1  1.000 p.u. @ bus 1   

Voltage Angle  -3.67 deg   @ bus 5  0.00 deg   @ bus 1   

Lambda P   11.90 $/MWh @ bus 3 11.90 $/MWh @ bus 4   

Lambda Q0.00 $/MWh @ bus 1  0.00 $/MWh @ bus 1   

 



| Bus Data |



Bus  Voltage  Generation Load  Lambda($/MVA-hr)

  #   Mag(pu) Ang(deg)   P (MW)   Q (MVAr)   P (MW)   Q (MVAr) PQ   

- ---           ---  ---

1  1.0000.000*50.00  0.00   - -  11.899 -

2  1.000   -0.299 88.07  0.00   - -  11.899 -

3  1.000   -0.278 71.93  0.00   - -  11.899 -

4  1.000   -2.986   - -   70.00  0.0011.899 -

5  1.000   -3.666   - -   70.00  0.0011.899 -

6  1.000   -3.087   - -   70.00  0.0011.899 -

      

   Total:210.00  0.00210.00  0.00

 



| Branch Data  |



Brnch   From   ToFrom Bus Injection   To Bus Injection Loss (I^2 * Z)  

  # BusBusP (MW)   Q (MVAr)   P (MW)   Q (MVAr)   P (MW)   Q (MVAr)

-  -  -            

   1  1  2  2.61  0.00 -2.61  0.00 0.000  0.00

   2  1  4 26.06  0.00-26.06  0.00 0.000  0.00

   3  1  5 21.33  0.00-21.33  0.00 0.000  0.00

   4  2  3 -0.15  0.00  0.15  0.00 0.000  0.00

   5  2  4 46.91  0.00-46.91  0.00 0.000  0.00

   6  2  5 19.59  0.00-19.59  0.00 0.000  0.00

   7  2  6 24.33  0.00-24.33  0.00 0.000  0.00

   8  3  5 22.75  0.00-22.75  0.00 0.000  0.00

   9  3  6 49.03  0.00-49.03  0.00 0.000  0.00

  10  4  5  2.97  0.00 -2.97  0.00 0.000  0.00

  11  5  6 -3.37  0.00  3.37  0.00 0.000  0.00

   

Total: 0.000  0.00

 

==

Re: Question about LMP

[Carlos E Murillo-Sanchez]

  
  
Dear Victor:
  
  Derivation of the lagrangian function with respect to Pg1 yields
  the first order optimality condition
  
  f'(Pg1) + mu_+ - mu_-    - \lambda_P1 = 0
  
  or \lambda_P1 = f'(Pg1) + mu_+ - mu_-
  
  where \lambda_P1 is the multiplier on bus' 1 balance constraint;
  mu_+ is the multiplier on the upper limit constraint for Pg1, and
  mu_- is the corresponding multiplier for the lower limit
  constraint.    In your example, \lambda_P1 = 11.899 (in fact for
  all buses), 
  
  Absent congestion, the balance constraint multiplier must be the
  same for all buses.  In the solution, the generator is against its
  lower limit. So mu_+ = 0,  mu_- = 0.303 and lambda_P1 = 11.899  . 
  You should convince yourself that at the solution, the marginal
  cost of the generator evaluates to 11.899+0.303 = f'(Pg1) .
  
  Carlos.
  
  Victor Hugo Hinojosa M. wrote:


  
  
  
  
Thank you so much for the information Prof.
Zimmerman.
I’d like your explanation about the simulation
for the 6-bus system (Wood & Wollemberg). When I run a
DCOPF with the original case (rundcopf(case6ww)), the LMP
shown for Matpower are the same (11.899 $/MWh) for all buses
because there isn’t congestion in the transmission lines.
Despite of the fact that the Lagrange multiplier for
generator 1 is active (0.303 $/MWh), the LMP are the same.
In my opinion, the LPM from bus 1 should be 12.202 $/MWh.
I’ll wait for your comments.
Regards,
Vh
 
 
MATPOWER Version 5.1, 20-Mar-2015 -- DC Optimal
Power Flow
Gurobi Version 6.0.4 -- automatic QP solver
 
Converged in 0.16 seconds
Objective Function Value = 3046.41 $/hr

| System
Summary  
|

 
How many?    How much? 
P (MW)    Q (MVAr)
-    --- 
-  -
Buses  6 Total Gen Capacity
530.0   0.0 to 0.0
Generators 3 On-line Capacity  
530.0   0.0 to 0.0
Committed Gens 3     Generation (actual)   
210.0   0.0
Loads  3 Load  
210.0   0.0
  Fixed    3   Fixed   
210.0   0.0
  Dispatchable 0  
Dispatchable  -0.0 of -0.0  -0.0
Shunts 0 Shunt
(inj) -0.0   0.0
Branches  11 Losses (I^2 *
Z) 0.00  0.00
Transformers   0 Branch Charging
(inj) -    0.0
Inter-ties 0 Total Inter-tie
Flow 0.0   0.0
Areas  1
 
 
Minimum  Maximum
 - 

Voltage Magnitude   1.000 p.u. @ bus 1 
1.000 p.u. @ bus 1   
Voltage Angle  -3.67 deg   @ bus 5 
0.00 deg   @ bus 1   
Lambda P   11.90 $/MWh @ bus 3
11.90 $/MWh @ bus 4   
Lambda Q    0.00 $/MWh @ bus 1 
0.00 $/MWh @ bus 1   
 

| Bus
Data
|

 Bus  Voltage 
Generation Load  Lambda($/MVA-hr)
  #   Mag(pu) Ang(deg)   P (MW)   Q (MVAr)   P
(MW)   Q (MVAr) P    Q   
- ---      
    ---  ---
    1  1.000    0.000*    50.00  0.00  
- -  11.899 -
    2  1.000   -0.299 88.07  0.00  
- -  11.899 -
    3  1.000   -0.278 71.93  0.00  
- -  11.899 -
    4  1.000   -2.986   - -  
70.00  0.00    11.899 -
    5  1.000   -3.666   - -  
   

RE: Question about LMP

[Sarmad Hanif]

Dear Vh,

Regarding your question: why LMP doesn’t include the Lagrange multipliers 
related to generation inequality constraints

The answer is it does!! As Carlos explained:

f'(Pg1) + mu_+ - mu_-- \lambda_P1 = 0

or \lambda_P1 = f'(Pg1) + mu_+ - mu_-

Your dual problem should also state the same.

As far as the interpretation goes for the LMP, quoting Ray’s response for an 
uncongested case:

LMP will equal the marginal cost of generation plus (minus) the shadow price on 
the binding upper (lower) generation constraint.


Regarding the book “ Spot pricing of electricity”, I haven’t read it yet. 
Hopefully, I will get my hands on it soon!

I hope this clears.

Regards,

Sarmad





From: bounce-119913453-74036...@list.cornell.edu 
[mailto:bounce-119913453-74036...@list.cornell.edu] On Behalf Of Victor Hugo 
Hinojosa M.
Sent: Thursday, 19 November, 2015 9:28 PM
To: 'MATPOWER discussion forum'
Subject: RE: Question about LMP

Dear Jovan and Sarmad,
I agree with your comments about LMP. In this analysis I’m not considered the 
congestion. If the generation inequality constraints aren’t active, Matpower 
prints this information correctly, and It’s possible to realize different 
prices when the lines is congested. Sarmad, I’ve verified your idea. Despite 
the fact that the shadow price for the minimum or maximum is active, the LMP 
shown are the same for all buses.
My question is about why LMP doesn’t include the Lagrange multipliers related 
to generation inequality constraints. I did a model using the dual problem for 
the DCOPF, and I realized that dual constraints are the prices for each buses. 
It’s very clear in those constraints that those “prices” take into account the 
marginal cost, the congestion cost through the partial transmission 
distribution factors (PTDF) and the generation constraints.
In the technical literature for the DCOPF (losses are neglected), the LPM are 
modeled considering energy cost and congestion cost. However, in the book “Spot 
pricing of electricity” from F. Schweppe et all, authors include these shadow 
prices in order to compute the spot prices.
I’d like to know your feedback about these comments.
Regards,
Vh

De: 
bounce-119912654-12657...@list.cornell.edu
 [mailto:bounce-119912654-12657...@list.cornell.edu] En nombre de Jovan Ilic
Enviado el: jueves, 19 de noviembre de 2015 1:13
Para: MATPOWER discussion forum
Asunto: Re: Question about LMP


Dear Victor,

If there is no congestion in the network, there is the same LMP at all the 
nodes.
The LMP consists of loss, congestion, and energy costs. DCOPF has no
losses, and if there is no congestion only the energy cost is accounted for.
You can think of it as if since there is no congestion or loss cost the energy 
can
be distributed to all nodes at the same price.

Regards,
Jovan Ilic

On Wed, Nov 18, 2015 at 4:37 PM, Victor Hugo Hinojosa M. 
mailto:victor.hinoj...@usm.cl>> wrote:
Dear Prof. Zimmerman,

I have a question about Local Marginal Prices (LMP) that are shown in
Matpower.

The definition of the LMP is the marginal cost of supplying, at least cost,
the next increment of electric demand at a specific location (node) on the
electric power network, taking into account both supply (generation/import)
bids and demand (load/export) offers and the physical aspects of the
transmission system including transmission and other operational
constraints.

When it is performed a DCOPF, Matpower shows LMP for each bus considering
the marginal cost (energy cost) and the congestion cost so that I'd like to
know why the generation constraints (maximum and minimum power) aren't
considered in the LMP.

Thank you so much for your ideas and comments.

Regards,

Vh

Different results with MATPOWER and PSAT

[Yogess H Singh]

Dear Fellow Member,

I ran load flow analysis on a IEEE-14 bus system using MATPOWER, PSAT and
PowerWorld. Voltage magnitudes as well as phases have slightly different
values in all three tools. However, the difference is not much but I want
to know what causes difference among results obtained with different
software tool even if all the parameters are exactly same?


Best Regards,

*Yogesh Kumar*
*Graduate Research Assistant*
*NE 2042, EECS Department*
*University of Toledo, OH 43507*
*+1 (419)530-8295 <%2B1%20%28419%29450-2217>*

Re: Different results with MATPOWER and PSAT

[Shruti Rao]

If the system parameters are the same, it could be because the tolerance
levels that were set for the different software were different i.e. the
default power balance mismatch tolerances are not always the same in all
software. Also probably if the VAR limits are active for PV buses,
different software often have slightly different algorithms for bus-type
switching and that could affect the solution maybe? Hope this helps.

Shruti

On Thu, Nov 19, 2015 at 9:12 PM, Yogess H Singh  wrote:

> Dear Fellow Member,
>
> I ran load flow analysis on a IEEE-14 bus system using MATPOWER, PSAT and
> PowerWorld. Voltage magnitudes as well as phases have slightly different
> values in all three tools. However, the difference is not much but I want
> to know what causes difference among results obtained with different
> software tool even if all the parameters are exactly same?
>
>
> Best Regards,
>
> *Yogesh Kumar*
> *Graduate Research Assistant*
> *NE 2042, EECS Department*
> *University of Toledo, OH 43507*
> *+1 (419)530-8295 <%2B1%20%28419%29450-2217>*
>



-- 
Regards,
Shruti Dwarkanath Rao

Graduate Research Assistant, Arizona State University
Vice Chair: IEEE PES ASU Student Chapter
Tempe, AZ, 85281
650 996 0116