Dear Prof. Zimmerman, thank you very much for answering.
Please find the attached files to follow my explanation.
I did a runopf('case2Q_PosTotalCost') and later runopf('case2Q_NegTotalCost')
If you compare both case files the only difference is at Gen 3 which it is 10
times more expensive.
Why do I get negative prices? Shouldn't I get higher OPF costs for having a
more expensive system?
I would expect that the system with more expensive MVAR prices to have higher
total OPF costs but it gives negative OPF costs.
I use the Matpower 3.2 and I have updated all the toolboxes
I appreciate your help and thank you for sharing this excellent tool
Kindest regards
Gabriel
From: [email protected]
To: [email protected]
Subject: Re: Reactive Power Bug
Date: Thu, 4 Jun 2009 15:42:36 -0400
Negative prices could be correct depending on the costs. Could you please send
me an example case file that exhibits the issue along with an explanation of
what you expected to be different from the output MATPOWER gives?
-- Ray ZimmermanSenior Research Associate428-B Phillips Hall, Cornell
University, Ithaca, NY 14853phone: (607) 255-9645
On Jun 4, 2009, at 3:27 PM, Gabox . wrote:Dear Sirs,
I use the OPF tools of matpower to test the effect of Reactive Power prices.
I build a case file similar to case30Q.m and I considered the reactive power
prices.
A generator dispatched with negative MVAR caused to get a wrong total cost of
the OPF
In the case of dispatching only negative MVAR, the OPF will get negative total
costs.
Is this a bug or there is another way to introduce reactive power prices in the
case files?
Could there be a missing abs() in the MVAR pricing?
I would appreciate your comments and help
Kind regards
¡Es hora que descubras quién sos! Alguien puede conocerte mejor que vos mismo.
_________________________________________________________________
Probá los mejores juegos online en MSN
http://juegos.ar.msn.com/>> runopf('case2Q_PosTotalCost')
Converged in 0.01 seconds
Objective Function Value = 42.32 $/hr
================================================================================
| System Summary |
================================================================================
How many? How much? P (MW) Q (MVAr)
--------------------- ------------------- ------------- -----------------
Buses 3 Total Gen Capacity 210.0 -55.0 to 272.5
Generators 3 On-line Capacity 210.0 -55.0 to 272.5
Committed Gens 3 Generation (actual) 24.2 8.6
Loads 2 Load 24.1 13.9
Fixed 2 Fixed 24.1 13.9
Dispatchable 0 Dispatchable -0.0 of -0.0 -0.0
Shunts 0 Shunt (inj) -0.0 0.0
Branches 2 Losses (I^2 * Z) 0.05 0.18
Transformers 0 Branch Charging (inj) - 5.5
Inter-ties 0 Total Inter-tie Flow 0.0 0.0
Areas 1
Minimum Maximum
------------------------- --------------------------------
Voltage Magnitude 1.037 p.u. @ bus 3 1.050 p.u. @ bus 1
Voltage Angle -0.03 deg @ bus 2 0.79 deg @ bus 3
P Losses (I^2*R) - 0.04 MW @ line 2-3
Q Losses (I^2*X) - 0.14 MVAr @ line 2-3
Lambda P 2.13 $/MWh @ bus 3 2.15 $/MWh @ bus 2
Lambda Q 0.26 $/MWh @ bus 1 0.29 $/MWh @ bus 3
================================================================================
| Bus Data |
================================================================================
Bus Voltage Generation Load Lambda($/MVA-hr)
# Mag(pu) Ang(deg) P (MW) Q (MVAr) P (MW) Q (MVAr) P Q
----- ------- -------- -------- -------- -------- -------- ------- -------
1 1.050 0.000 3.66 6.54 - - 2.146 0.262
2 1.045 -0.029 11.45 7.76 21.70 12.70 2.151 0.272
3 1.037 0.793 9.05 -5.68 2.40 1.20 2.131 0.290
-------- -------- -------- --------
Total: 24.15 8.62 24.10 13.90
================================================================================
| Branch Data |
================================================================================
Brnch From To From Bus Injection To Bus Injection Loss (I^2 * Z)
# Bus Bus P (MW) Q (MVAr) P (MW) Q (MVAr) P (MW) Q (MVAr)
----- ----- ----- -------- -------- -------- -------- -------- --------
1 1 2 3.66 6.54 -3.64 -9.79 0.015 0.04
2 2 3 -6.61 4.85 6.65 -6.88 0.036 0.14
-------- --------
Total: 0.051 0.18
================================================================================
| Voltage Constraints |
================================================================================
Bus # Vmin mu Vmin |V| Vmax Vmax mu
----- -------- ----- ----- ----- --------
1 - 0.950 1.050 1.050 3.168
>> runopf('case2Q_NegTotalCost')
Converged in 0.05 seconds
Objective Function Value = -86.20 $/hr
================================================================================
| System Summary |
================================================================================
How many? How much? P (MW) Q (MVAr)
--------------------- ------------------- ------------- -----------------
Buses 3 Total Gen Capacity 210.0 -55.0 to 272.5
Generators 3 On-line Capacity 210.0 -55.0 to 272.5
Committed Gens 3 Generation (actual) 24.3 9.1
Loads 2 Load 24.1 13.9
Fixed 2 Fixed 24.1 13.9
Dispatchable 0 Dispatchable -0.0 of -0.0 -0.0
Shunts 0 Shunt (inj) -0.0 0.0
Branches 2 Losses (I^2 * Z) 0.16 0.60
Transformers 0 Branch Charging (inj) - 5.4
Inter-ties 0 Total Inter-tie Flow 0.0 0.0
Areas 1
Minimum Maximum
------------------------- --------------------------------
Voltage Magnitude 1.017 p.u. @ bus 3 1.050 p.u. @ bus 1
Voltage Angle 0.00 deg @ bus 1 1.11 deg @ bus 3
P Losses (I^2*R) - 0.13 MW @ line 2-3
Q Losses (I^2*X) - 0.50 MVAr @ line 2-3
Lambda P 2.13 $/MWh @ bus 3 2.15 $/MWh @ bus 2
Lambda Q 0.44 $/MWh @ bus 1 0.52 $/MWh @ bus 3
================================================================================
| Bus Data |
================================================================================
Bus Voltage Generation Load Lambda($/MVA-hr)
# Mag(pu) Ang(deg) P (MW) Q (MVAr) P (MW) Q (MVAr) P Q
----- ------- -------- -------- -------- -------- -------- ------- -------
1 1.050 0.000 3.70 10.99 - - 2.148 0.440
2 1.042 0.016 11.53 13.10 21.70 12.70 2.154 0.459
3 1.017 1.108 9.04 -15.00 2.40 1.20 2.129 0.520
-------- -------- -------- --------
Total: 24.26 9.10 24.10 13.90
================================================================================
| Branch Data |
================================================================================
Brnch From To From Bus Injection To Bus Injection Loss (I^2 * Z)
# Bus Bus P (MW) Q (MVAr) P (MW) Q (MVAr) P (MW) Q (MVAr)
----- ----- ----- -------- -------- -------- -------- -------- --------
1 1 2 3.70 10.99 -3.67 -14.18 0.032 0.09
2 2 3 -6.50 14.58 6.64 -16.20 0.133 0.50
-------- --------
Total: 0.164 0.60
================================================================================
| Voltage Constraints |
================================================================================
Bus # Vmin mu Vmin |V| Vmax Vmax mu
----- -------- ----- ----- ----- --------
1 - 0.950 1.050 1.050 6.146
================================================================================
| Generation Constraints |
================================================================================
Gen Bus Reactive Power Limits
# # Qmin mu Qmin Qg Qmax Qmax mu
--- --- ------- -------- -------- -------- -------
3 3 7.605 -15.00 -15.00 62.50 -
function [baseMVA, bus, gen, branch, areas, gencost] = case30Q
%CASE30Q Case 30 with costs for reactive generation.
% Please see 'help caseformat' for details on the case file format.
%
% Identical to case30.m, with the addition of non-zero costs for
% reactive power.
% MATPOWER
% $Id: case30Q.m,v 1.7 2007/09/17 16:07:48 ray Exp $
%%----- Power Flow Data -----%%
%% system MVA base
baseMVA = 100;
%% bus data
%bus_i type Pd Qd Gs Bs area Vm Va baseKV zone Vmax Vmin
bus = [
1 3 0 0 0 0 1 1 0 135 1 1.05 0.95;
2 2 21.7 12.7 0 0 1 1 0 135 1 1.1 0.95;
3 1 2.4 1.2 0 0 1 1 0 135 1 1.05 0.95;
];
% PQ bus = 1
% PV bus = 2
% reference bus = 3
% isolated bus = 4
%% generator data
%bus Pg Qg Qmax Qmin Vg mBase status Pmax Pmin
gen = [
1 0 0 150 -20 1 100 1 80 0;
2 0 0 60 -20 1 100 1 80 0;
3 0 0 62.5 -15 1 100 1 50 0;
];
%% branch data
% fbus tbus r x b rateA rateB rateC ratio angle status
branch = [
1 2 0.02 0.06 0.03 130 130 130 0 0 1;
2 3 0.05 0.19 0.02 130 130 130 0 0 1;
];
%%----- OPF Data -----%%
%% area data
areas = [
1 1;
];
%% generator cost data
% 1 startup shutdown n x1 y1 ... xn yn
% 2 startup shutdown n c(n-1) ... c0
gencost = [
2 0 0 3 0.02 2 0;
2 0 0 3 0.0175 1.75 0;
2 0 0 3 0.0625 1 0;
%Reactive Power Cost from here on
2 0 0 3 0.02 0 0;
2 0 0 3 0.0175 0 0;
2 0 0 3 0.0625 1 0;
];
return;
function [baseMVA, bus, gen, branch, areas, gencost] = case30Q
%CASE30Q Case 30 with costs for reactive generation.
% Please see 'help caseformat' for details on the case file format.
%
% Identical to case30.m, with the addition of non-zero costs for
% reactive power.
% MATPOWER
% $Id: case30Q.m,v 1.7 2007/09/17 16:07:48 ray Exp $
%%----- Power Flow Data -----%%
%% system MVA base
baseMVA = 100;
%% bus data
%bus_i type Pd Qd Gs Bs area Vm Va baseKV zone Vmax Vmin
bus = [
1 3 0 0 0 0 1 1 0 135 1 1.05 0.95;
2 2 21.7 12.7 0 0 1 1 0 135 1 1.1 0.95;
3 1 2.4 1.2 0 0 1 1 0 135 1 1.05 0.95;
];
% PQ bus = 1
% PV bus = 2
% reference bus = 3
% isolated bus = 4
%% generator data
%bus Pg Qg Qmax Qmin Vg mBase status Pmax Pmin
gen = [
1 0 0 150 -20 1 100 1 80 0;
2 0 0 60 -20 1 100 1 80 0;
3 0 0 62.5 -15 1 100 1 50 0;
];
%% branch data
% fbus tbus r x b rateA rateB rateC ratio angle status
branch = [
1 2 0.02 0.06 0.03 130 130 130 0 0 1;
2 3 0.05 0.19 0.02 130 130 130 0 0 1;
];
%%----- OPF Data -----%%
%% area data
areas = [
1 1;
];
%% generator cost data
% 1 startup shutdown n x1 y1 ... xn yn
% 2 startup shutdown n c(n-1) ... c0
gencost = [
2 0 0 3 0.02 2 0;
2 0 0 3 0.0175 1.75 0;
2 0 0 3 0.0625 1 0;
%Reactive Power Cost from here on
2 0 0 3 0.02 0 0;
2 0 0 3 0.0175 0 0;
2 0 0 3 0.0625 10 0;
];
return;
