convergence problem in runpf.
Dear Matpower Community,
I’m working on power flow project and have used grid data from database. I
have modelled all line parameters (R X B) in p.u. system, also same for
transformers and kept generator output until it satisfies active and
reactive power demand. For renewable generation, I specified as negative
demand on respective buses. I checked all possibilities mentioned in FAQ (
http://www.pserc.cornell.edu/matpower/#pfconvergence ) but couldn’t figure
out problem. Also I checked (case_info) to see any island but got full
system without island. To make the problem simple I used all buses as PQ
buses except one slack bus. Also my casefile converges for rundcpf but
fails to runpf and gives error like ‘Newton's method power flow did not
converge in 10 iterations.’ Also I found that when I use following code-
opt = mpoption('OUT_BUS', 0, 'OUT_BRANCH', 0, 'VERBOSE', 2);
mpc = loadcase('casefile');
results =runpf(mpc,opt);
may be it gives me divergence of PQ mismatch instead of convergence.
MATPOWER Version 5.1, 20-Mar-2015 -- AC Power Flow (Newton)
itmax P Q mismatch (p.u.)
---
0 2.296e+01
1 1.729e+01
2 2.450e+03
3 2.352e+03
4 6.962e+06
5 1.740e+06
6 4.352e+05
7 1.753e+07
8 4.382e+06
9 3.322e+06
10 8.303e+05
Newton's method power flow did not converge in 10 iterations.
Did NOT converge (0.23 seconds)
results =
version: '2'
baseMVA: 100
bus: [1086x13 double]
gen: [467x21 double]
branch: [2145x17 double]
order: [1x1 struct]
et: 0.2320
success: 0
I will be very thankful for your help.
Regards
Mirish Thakur.
KIT, University.
Re: convergence problem in runpf.
I would suggest trying the following:
1. Use the solution of a fast decoupled power flow or an optimal power flow
(with line limits and voltage limits relaxed) as the initial guess for the
power flow.
2. Follow step 5 in http://www.pserc.cornell.edu/matpower/#pfconvergence
making CPF to stop when the nose-point is reached. This can be done via results
= runcpf(mpcbase,mpctarget,mpoption(‘cpf.stop_at’,’NOSE’)). If
results.cpf.max_lam is = 1, then it shows that the initial guess for the power
flow is the problem for its divergence. To obtain a ‘good’ initial guess, run
the continuation power flow again making it to stop exactly at lam = 1 (the
target case loading and generation) via results =
runcpf(mpcbase,mpctarget,mpoption(‘cpf.stop_at’,1.0)). You can then save the
results struct as a matpower case file (via savecase()). On the other hand, if
results.cpf.max_lam 1, then the loading/generation in your original case is
beyond the system steady-state loading limit.
Shri
From: Mirish Thakur mirishtha...@gmail.commailto:mirishtha...@gmail.com
Reply-To: MATPOWER discussion forum
matpowe...@list.cornell.edumailto:matpowe...@list.cornell.edu
Date: Monday, August 10, 2015 at 10:44 AM
To: MATPOWER discussion forum
matpowe...@list.cornell.edumailto:matpowe...@list.cornell.edu
Subject: convergence problem in runpf.
Dear Matpower Community,
I’m working on power flow project and have used grid data from database. I have
modelled all line parameters (R X B) in p.u. system, also same for transformers
and kept generator output until it satisfies active and reactive power demand.
For renewable generation, I specified as negative demand on respective buses. I
checked all possibilities mentioned in FAQ
(http://www.pserc.cornell.edu/matpower/#pfconvergence ) but couldn’t figure out
problem. Also I checked (case_info) to see any island but got full system
without island. To make the problem simple I used all buses as PQ buses except
one slack bus. Also my casefile converges for rundcpf but fails to runpf and
gives error like ‘Newton's method power flow did not converge in 10
iterations.’ Also I found that when I use following code-
opt = mpoption('OUT_BUS', 0, 'OUT_BRANCH', 0, 'VERBOSE', 2);
mpc = loadcase('casefile');
results =runpf(mpc,opt);
may be it gives me divergence of PQ mismatch instead of convergence.
MATPOWER Version 5.1, 20-Mar-2015 -- AC Power Flow (Newton)
itmax P Q mismatch (p.u.)
---
0 2.296e+01
1 1.729e+01
2 2.450e+03
3 2.352e+03
4 6.962e+06
5 1.740e+06
6 4.352e+05
7 1.753e+07
8 4.382e+06
9 3.322e+06
10 8.303e+05
Newton's method power flow did not converge in 10 iterations.
Did NOT converge (0.23 seconds)
results =
version: '2'
baseMVA: 100
bus: [1086x13 double]
gen: [467x21 double]
branch: [2145x17 double]
order: [1x1 struct]
et: 0.2320
success: 0
I will be very thankful for your help.
Regards
Mirish Thakur.
KIT, University.
Re: questions on optimal power flow
You can modify the test case so that the bounds are very tight on the variables you would like to keep constant. Cheers, -Carleton On Aug 10, 2015, at 9:53 PM, rainy chung chunyu...@gmail.com wrote: Hi Matpower communities, The default runopf change all the control inputs, such as active power and terminal voltage of PV buses. Is it possible to only change the values of a specific subsets of , for example, PV bus instead of all of it! Many Thanks! Best Regards! The information in this e-mail may be confidential and subject to legal professional privilege and/or copyright. National ICT Australia Limited accepts no liability for any damage caused by this email or its attachments.
Re: questions on optimal power flow
Thanks Sir, I will try that. By the way, I am wondering whether you know how to add new varaibles z using direct specification method? Many thanks! Best Regards! 2015-08-11 6:35 GMT+08:00 Carleton Coffrin carleton.coff...@nicta.com.au: You can modify the test case so that the bounds are very tight on the variables you would like to keep constant. Cheers, -Carleton On Aug 10, 2015, at 9:53 PM, rainy chung chunyu...@gmail.com wrote: Hi Matpower communities, The default runopf change all the control inputs, such as active power and terminal voltage of PV buses. Is it possible to only change the values of a specific subsets of , for example, PV bus instead of all of it! Many Thanks! Best Regards! The information in this e-mail may be confidential and subject to legal professional privilege and/or copyright. National ICT Australia Limited accepts no liability for any damage caused by this email or its attachments.
Re: PV curve using CPF
Shruti is right, the value you obtain for lambda is valid for all the network, since voltage collapse is a global phenomenon (in other words, you'll see a nose point at the same value of lambda regardless of which bus you choose to plot). Remember that lambda represents a fraction along the vector of injections linearly iterpolating [P_base, Q_base] to [P_target, Q_target]. The value of Lambda at the nose point is NOT the maximum loading point for that bus; rather, it is the maximum loading value along the path to the particular load/gen profile chosen as a target. Of course, one may wonder about this other problem: for a given profile [P_base, Q_base], what is the target direction [P_target, Q_target] for which one would obtain the shortest value of critical lambda? If this is what you're thinking about, then it is in general a hard problem. I suggest these references by Ian Dobson, on the concept of shortest distance to voltage collapse: - http://www.ece.wisc.edu/~dobson/PAPERS/publications.html#loading -- Jose L. Marin Gridquant España SL Grupo AIA On Mon, Aug 10, 2015 at 6:23 AM, nilesh patel nk2...@rediffmail.com wrote: Sir, When we run continuation power flow for particular system, we get p-v curve for selected bus. using this p-v curve, we can find Voltage stability Margin (in MW) on that bus by difference of operating point to nose point lamda. I agree lambda at nose point provides maximum loading value but that is for that bus only for which p-v curve is plotted. My question is How to find Voltage Stability Margin for whole Network using P-V curve ? I mean how to find maximum lamda for whole network using p-v curve? Thanks. From: Abhyankar, Shrirang G. abhy...@anl.gov Sent: Fri, 07 Aug 2015 22:31:31 To: MATPOWER discussion forum matpowe...@list.cornell.edu Subject: Re: PV curve using CPF I donⴠquite understand your question, can you please elaborate. The maximum value of loading scaling parameter ᬡmbda⠧ives a measure of how much power can be transferred for a given transfer direction. So, lambda is also a measure of the nose point for the whole network. Shri From: nilesh patel nk2...@rediffmail.com Reply-To: MATPOWER discussion forum matpowe...@list.cornell.edu Date: Friday, August 7, 2015 at 8:46 AM To: matpower-l matpowe...@list.cornell.edu, MATPOWER-L MATPOWER-L@cornell.edu Subject: PV curve using CPF Dear Sir, P-V curve solution using continuation power flow gives nose point (maximum loading point) for individual bus. My question is - How to get nose point for whole network (all buses) using PV curve ? I want to find network voltage stability margin rather than individual bus margin using CPF. Thanks. Nilesh Patel Get your own *FREE* website, *FREE* domain *FREE* mobile app with Company email. *Know More * //www.rediffmail.com/cgi-bin/red.cgi?red=http%3A%2F%2Ftrack%2Erediff%2Ecom%2Fclick%3Furl%3D%5F%5F%5Fhttp%3A%2F%2Fbusinessemail%2Erediff%2Ecom%3Fsc%5Fcid%3Dsign%2D1%2D10%2D13%5F%5F%5F%26amp%3Bcmp%3Dhost%26amp%3Blnk%3Dsign%2D1%2D10%2D13%26amp%3Bnsrv1%3DhostisImage=0BlockImage=0rediffng=0rogue=387537254f7eee557c3b17544bd037e8098bd82e https://sigads.rediff.com/RealMedia/ads/click_nx.ads/www.rediffmail.com/signatureline.htm@Middle? https://sigads.rediff.com/RealMedia/ads/click_nx.ads/www.rediffmail.com/signatureline.htm@Middle? Get your own *FREE* website, *FREE* domain *FREE* mobile app with Company email. *Know More * http://track.rediff.com/click?url=___http://businessemail.rediff.com?sc_cid=sign-1-10-13___cmp=hostlnk=sign-1-10-13nsrv1=host
questions on optimal power flow
Hi Matpower communities, The default runopf change all the control inputs, such as active power and terminal voltage of PV buses. Is it possible to only change the values of a specific subsets of , for example, PV bus instead of all of it! Many Thanks! Best Regards!
