Re: Continuous power flow question

[Abhyankar, Shrirang G]

Hi Simone,
   See the FAQ on power flow 
divergence<https://matpower.org/doc/faq/#pfconvergence>. It lists some useful 
tips to debug power flow divergence when using MATPOWER and how to run a 
continuation power flow to check if a power flow solution exists (point v).

Thanks,
Shri


From:  on behalf of Simone Fratton 

Reply-To: MATPOWER discussion forum 
Date: Tuesday, June 1, 2021 at 4:08 AM
To: "matpowe...@list.cornell.edu" 
Subject: Continuous power flow question

Check twice before you click! This email originated from outside PNNL.

Hi,
I would like to ask where I can find specific indications on the use of 
"continuous power flow" in Matpower? Maybe a video, an example Specifically 
I have a case (an electrical grid) for which Newton-Rapshon does not converge 
even if a solution exists and I thought of the "continuous power flow" to find 
this solution. I don't know if I can do it and also how to do it.
Thank you all and I apologize so much for the inconvenience.

Continuous power flow question

[Simone Fratton]

Hi,

I would like to ask where I can find specific indications on the use of
"continuous power flow" in Matpower? Maybe a video, an example
Specifically I have a case (an electrical grid) for which Newton-Rapshon
does not converge even if a solution exists and I thought of the
"continuous power flow" to find this solution. I don't know if I can do it
and also how to do it.

Thank you all and I apologize so much for the inconvenience.

?????? AC power flow question

[????]

Dear Dr.Zimmerman:
 It is my pleasure to get your response! I find that even if we don't turn 
off those generators whose reactive power is out of the limit, just only 
adjusting their output to a reasonable value is also feasible. When we adjust a 
generator, we run the power flow again, if we find there is a generator 
exceeding the limit, we again adjust the output until the all generators' 
reactive outputs are under the limit. No matter how, it is really a perfect 
experience for me to get the response by yourself. When I see the matpoer code, 
I am sur that I am one of your fans! Thank you very much!
  

 

 --  --
  ??: "Ray Zimmerman";<r...@cornell.edu>;
 : 2016??6??3??(??) 0:09
 ??: "MATPOWER discussion forum"<matpowe...@list.cornell.edu>; 
 
 : Re: AC power flow question

 

If you look more carefully at the code (and the comments) you??ll see that the 
generator is turned off temporarily in line 267, and the load is adjusted to 
include the injection. Later in line 307, the process is reversed, turning the 
generator back on. Without studying the code in more detail, I don??t remember 
why it was done this way, but I suspect it has something to do with multiple 
generators at a bus.

 Ray


> On Jun 2, 2016, at 10:05 AM,  <1499730...@qq.com> wrote:
> 
> Dear Sir/Madam,
> I have a question with the AC power flow calculation. In Matpower 
> 5.1, when AC power flow is calculated, if the q_limt is used, as the manual 
> states that "If any generator has a violated reactive power limit, its 
> reactive injection is fixed at the limit, the corresponding bus is converted 
> to a PQ bus and the power flow is solved again. This procedure is repeated 
> until there are no more violations". Obviously, we can find that all 
> generators violating the reactive power limit will be regared as PQ bus, then 
> the power flow will be recalculated. However, when I opened the file runpf.m, 
>  I fund that the states of all generators violating the reactive power limit 
> are set to be zero, that is, "gen(mx, GEN_STATUS) = 0";. That means the 
> generation is turned off in the next power flow re-calculation. This isn't 
> included in the manual. It seems unreasonable. So I want to know the reason 
> why turn off all these generators.

Re: AC power flow question

[Ray Zimmerman]

If you look more carefully at the code (and the comments) you’ll see that the 
generator is turned off temporarily in line 267, and the load is adjusted to 
include the injection. Later in line 307, the process is reversed, turning the 
generator back on. Without studying the code in more detail, I don’t remember 
why it was done this way, but I suspect it has something to do with multiple 
generators at a bus.

 Ray


> On Jun 2, 2016, at 10:05 AM, 严超 <1499730...@qq.com> wrote:
> 
> Dear Sir/Madam,
> I have a question with the AC power flow calculation. In Matpower 
> 5.1, when AC power flow is calculated, if the q_limt is used, as the manual 
> states that "If any generator has a violated reactive power limit, its 
> reactive injection is fixed at the limit, the corresponding bus is converted 
> to a PQ bus and the power flow is solved again. This procedure is repeated 
> until there are no more violations". Obviously, we can find that all 
> generators violating the reactive power limit will be regared as PQ bus, then 
> the power flow will be recalculated. However, when I opened the file runpf.m, 
>  I fund that the states of all generators violating the reactive power limit 
> are set to be zero, that is, "gen(mx, GEN_STATUS) = 0";. That means the 
> generation is turned off in the next power flow re-calculation. This isn't 
> included in the manual. It seems unreasonable. So I want to know the reason 
> why turn off all these generators. 

AC power flow question

[????]

Dear Sir/Madam,
 I have a question with the AC power flow calculation. In Matpower 5.1, 
when AC power flow is calculated, if the q_limt is used, as the manual states 
that "If any generator has a violated reactive power limit, its reactive 
injection is fixed at the limit, the corresponding bus is converted to a PQ bus 
and the power flow is solved again. This procedure is repeated until there are 
no more violations". Obviously, we can find that all generators violating the 
reactive power limit will be regared as PQ bus, then the power flow will be 
recalculated. However, when I opened the file runpf.m,  I fund that the states 
of all generators violating the reactive power limit are set to be zero, that 
is, "gen(mx, GEN_STATUS) = 0";. That means the generation is turned off in the 
next power flow re-calculation. This isn't included in the manual. It seems 
unreasonable. So I want to know the reason why turn off all these generators.

Re: power flow question

[Ray Zimmerman]

Good idea. That should probably be an option though.

Ray

> On Feb 18, 2016, at 11:58 AM, Abhyankar, Shrirang G. <abhy...@anl.gov> wrote:
> 
> I agree. Having the warnings for all generators, voltages, etc. would be 
> helpful for the cases when users are also varying the generation on PV buses. 
> I would even like MATPOWER fixing the active power at PV buses to the max. or 
> min. limit, if the generation exceeds these limits, and informing the users 
> via a warning.
> 
> Shri
> 
> From: Ray Zimmerman <r...@cornell.edu <mailto:r...@cornell.edu>>
> Reply-To: MATPOWER discussion forum <matpowe...@list.cornell.edu 
> <mailto:matpowe...@list.cornell.edu>>
> Date: Thursday, February 18, 2016 at 10:34 AM
> To: MATPOWER discussion forum <matpowe...@list.cornell.edu 
> <mailto:matpowe...@list.cornell.edu>>
> Subject: Re: power flow question
> 
> I agree that checking for exceeded limits and warning about them would be a 
> nice feature to add to the the power flow. I see no reason, though, why it 
> should be limited to the swing bus power injection … why not include all of 
> the other generator, voltage and branch flow limits, all of which can be 
> violated in a converged power flow solution.
> 
> I’ll put it on the “to do” list.
> 
>Ray
> 
> 
>> On Feb 18, 2016, at 8:05 AM, Jovan Ilic <jovan.i...@gmail.com 
>> <mailto:jovan.i...@gmail.com>> wrote:
>> 
>> 
>> Jose,
>> 
>> I did not suggest to turn the swing bus into a PV bus. There should be at 
>> least one swing bus
>> in the system unless you formulate your PF problem as ACOPF problem which 
>> does not need
>> any slack buses. 
>> 
>> I understand what you are saying and you are right. I'd keep the swing bus 
>> as it is just
>> to provide the angle reference (admittance matrix is rarely singular) and 
>> add to Jacobian a
>> constraint on the sum of P and Q flows on the lines connected to the swing 
>> bus.  The sum 
>> of all these lines out flows must be less than the power injection 
>> capability of the swing bus, 
>> both P and Q. If the constraint is violated the power flow does not 
>> converge. The original 
>> poster was concerned with the convergence when there is not enough 
>> generation, so 
>> no convergence would give them a really stern "warning" and leave them 
>> guessing what went 
>> wrong.  Or you can just keep it simple and have PF implementation just print 
>> out a warning 
>> that the slack bus exceeded its capacity.  Modifying the Jacobian was the 
>> first thing that
>> came to my mind but I am not sure if it provides anything in addition of a 
>> warning to user. 
>> 
>> Jovan
>> 
>> 
>> On Thu, Feb 18, 2016 at 3:25 AM, Jose Luis Marin <mari...@gridquant.com 
>> <mailto:mari...@gridquant.com>> wrote:
>> But you did that, it would no longer be a powerflow calculation.  There are 
>> good mathematical reasons why the standard powerflow calculation is 
>> formulated so that there should be at least one swing bus (where you specify 
>> both V and A, leaving P and Q "free").  If you specified V, A, and Pgen at 
>> the swing, this would yield an overdetermined system.  You could 
>> theoretically formulate a powerflow in which the swing bus specified only A 
>> (the global angle reference) and Pgen, leaving Vref and Qgen free, but this 
>> would yield a system of equations with a severe pathology, namely a 
>> near-singular Jacobian (this originates from the fact that the full 
>> transmission admittance matrix, being a Laplacian matrix, always has a zero 
>> eigenvalue, which corresponds to a translation symmetry consisting in 
>> uniformly shifting all voltages;  pinning down at least one voltage is what 
>> breaks this symmetry and recovers invertibility).
>> 
>> However, I think you're right it would be a good idea to *warn* the user 
>> when the swing generator(s) have gone over their PMAX (or below their PMIN!).
>> 
>> -- 
>> Jose L. Marin
>> Grupo AIA
>> 
>> 
>> On Thu, Feb 18, 2016 at 12:08 AM, Jovan Ilic <jovan.i...@gmail.com 
>> <mailto:jovan.i...@gmail.com>> wrote:
>> 
>> Good point, maybe we should trow a Pgen constraint on the swing buses in the 
>> Jacobian. 
>> 
>>  
>> 
>> On Wed, Feb 17, 2016 at 5:30 PM, Santiago Torres <santiago.i...@gmail.com 
>> <mailto:santiago.i...@gmail.com>> wrote:
>> Because the exceding generation is supplied by the swing bus. Normal power 
>> flow does not check power generation limits.
>> 
>> El 17 feb. 2016 1:58 PM, "Bai, Wenlei" <wenlei_...@baylor.edu 
>> <mailto:wenlei_...@baylor.edu>> escribió:
>> Dear Ray,
>> 
>> I tried to modified load of ‘case9’ to exceed the total generation capacity 
>> purposely.
>> 
>> To my surprise, power flow still converges.  More specifically,  the total 
>> generator ‘on-line capacity’ is 820MW, while the ‘actual generation’ is 
>> 920.8MW
>> 
>> Why the actual generation can be larger than its capacity?
>> 
>>  
>> 
>> Blessings,
>> Wenlei
>> 
>>  
>> 
>> 
>> 
>> 
> 

Re: power flow question

[Abhyankar, Shrirang G.]

I agree. Having the warnings for all generators, voltages, etc. would be 
helpful for the cases when users are also varying the generation on PV buses. I 
would even like MATPOWER fixing the active power at PV buses to the max. or 
min. limit, if the generation exceeds these limits, and informing the users via 
a warning.

Shri

From: Ray Zimmerman <r...@cornell.edu<mailto:r...@cornell.edu>>
Reply-To: MATPOWER discussion forum 
<matpowe...@list.cornell.edu<mailto:matpowe...@list.cornell.edu>>
List-Post: matpower-l@cornell.edu
Date: Thursday, February 18, 2016 at 10:34 AM
To: MATPOWER discussion forum 
<matpowe...@list.cornell.edu<mailto:matpowe...@list.cornell.edu>>
Subject: Re: power flow question

I agree that checking for exceeded limits and warning about them would be a 
nice feature to add to the the power flow. I see no reason, though, why it 
should be limited to the swing bus power injection … why not include all of the 
other generator, voltage and branch flow limits, all of which can be violated 
in a converged power flow solution.

I’ll put it on the “to do” list.

   Ray


On Feb 18, 2016, at 8:05 AM, Jovan Ilic 
<jovan.i...@gmail.com<mailto:jovan.i...@gmail.com>> wrote:


Jose,

I did not suggest to turn the swing bus into a PV bus. There should be at least 
one swing bus
in the system unless you formulate your PF problem as ACOPF problem which does 
not need
any slack buses.

I understand what you are saying and you are right. I'd keep the swing bus as 
it is just
to provide the angle reference (admittance matrix is rarely singular) and add 
to Jacobian a
constraint on the sum of P and Q flows on the lines connected to the swing bus. 
 The sum
of all these lines out flows must be less than the power injection capability 
of the swing bus,
both P and Q. If the constraint is violated the power flow does not converge. 
The original
poster was concerned with the convergence when there is not enough generation, 
so
no convergence would give them a really stern "warning" and leave them guessing 
what went
wrong.  Or you can just keep it simple and have PF implementation just print 
out a warning
that the slack bus exceeded its capacity.  Modifying the Jacobian was the first 
thing that
came to my mind but I am not sure if it provides anything in addition of a 
warning to user.

Jovan


On Thu, Feb 18, 2016 at 3:25 AM, Jose Luis Marin 
<mari...@gridquant.com<mailto:mari...@gridquant.com>> wrote:
But you did that, it would no longer be a powerflow calculation.  There are 
good mathematical reasons why the standard powerflow calculation is formulated 
so that there should be at least one swing bus (where you specify both V and A, 
leaving P and Q "free").  If you specified V, A, and Pgen at the swing, this 
would yield an overdetermined system.  You could theoretically formulate a 
powerflow in which the swing bus specified only A (the global angle reference) 
and Pgen, leaving Vref and Qgen free, but this would yield a system of 
equations with a severe pathology, namely a near-singular Jacobian (this 
originates from the fact that the full transmission admittance matrix, being a 
Laplacian matrix, always has a zero eigenvalue, which corresponds to a 
translation symmetry consisting in uniformly shifting all voltages;  pinning 
down at least one voltage is what breaks this symmetry and recovers 
invertibility).

However, I think you're right it would be a good idea to *warn* the user when 
the swing generator(s) have gone over their PMAX (or below their PMIN!).

--
Jose L. Marin
Grupo AIA


On Thu, Feb 18, 2016 at 12:08 AM, Jovan Ilic 
<jovan.i...@gmail.com<mailto:jovan.i...@gmail.com>> wrote:

Good point, maybe we should trow a Pgen constraint on the swing buses in the 
Jacobian.



On Wed, Feb 17, 2016 at 5:30 PM, Santiago Torres 
<santiago.i...@gmail.com<mailto:santiago.i...@gmail.com>> wrote:

Because the exceding generation is supplied by the swing bus. Normal power flow 
does not check power generation limits.

El 17 feb. 2016 1:58 PM, "Bai, Wenlei" 
<wenlei_...@baylor.edu<mailto:wenlei_...@baylor.edu>> escribió:
Dear Ray,
I tried to modified load of ‘case9’ to exceed the total generation capacity 
purposely.
To my surprise, power flow still converges.  More specifically,  the total 
generator ‘on-line capacity’ is 820MW, while the ‘actual generation’ is 920.8MW
Why the actual generation can be larger than its capacity?

Blessings,
Wenlei

Re: power flow question

[Jose Luis Marin]

Hi Jovan,

Sorry, I see I misundertood.  I had read your proposal as consisting in
adding an *equality* constraint, instead of an *inequality* constraint.

But as you say, I suspect that such thing would be equivalent to just
adding a simple post-calculation check and a warning to the user when PG is
out of bounds (PMIN, PMAX).

-- 
Jose L. Marin
Grupo AIA


On Thu, Feb 18, 2016 at 2:05 PM, Jovan Ilic  wrote:

>
> Jose,
>
> I did not suggest to turn the swing bus into a PV bus. There should be at
> least one swing bus
> in the system unless you formulate your PF problem as ACOPF problem which
> does not need
> any slack buses.
>
> I understand what you are saying and you are right. I'd keep the swing bus
> as it is just
> to provide the angle reference (admittance matrix is rarely singular) and
> add to Jacobian a
> constraint on the sum of P and Q flows on the lines connected to the swing
> bus.  The sum
> of all these lines out flows must be less than the power injection
> capability of the swing bus,
> both P and Q. If the constraint is violated the power flow does not
> converge. The original
> poster was concerned with the convergence when there is not enough
> generation, so
> no convergence would give them a really stern "warning" and leave them
> guessing what went
> wrong.  Or you can just keep it simple and have PF implementation just
> print out a warning
> that the slack bus exceeded its capacity.  Modifying the Jacobian was the
> first thing that
> came to my mind but I am not sure if it provides anything in addition of a
> warning to user.
>
> Jovan
>
>
> On Thu, Feb 18, 2016 at 3:25 AM, Jose Luis Marin 
> wrote:
>
>> But you did that, it would no longer be a powerflow calculation.  There
>> are good mathematical reasons why the standard powerflow calculation is
>> formulated so that there should be at least one swing bus (where you
>> specify both V and A, leaving P and Q "free").  If you specified V, A, and
>> Pgen at the swing, this would yield an overdetermined system.  You could
>> theoretically formulate a powerflow in which the swing bus specified only A
>> (the global angle reference) and Pgen, leaving Vref and Qgen free, but this
>> would yield a system of equations with a severe pathology, namely a
>> near-singular Jacobian (this originates from the fact that the full
>> transmission admittance matrix, being a Laplacian matrix, always has a zero
>> eigenvalue, which corresponds to a translation symmetry consisting in
>> uniformly shifting all voltages;  pinning down at least one voltage is what
>> breaks this symmetry and recovers invertibility).
>>
>> However, I think you're right it would be a good idea to *warn* the user
>> when the swing generator(s) have gone over their PMAX (or below their
>> PMIN!).
>>
>> --
>> Jose L. Marin
>> Grupo AIA
>>
>>
>> On Thu, Feb 18, 2016 at 12:08 AM, Jovan Ilic 
>> wrote:
>>
>>>
>>> Good point, maybe we should trow a Pgen constraint on the swing buses in
>>> the Jacobian.
>>>
>>>
>>>
>>> On Wed, Feb 17, 2016 at 5:30 PM, Santiago Torres <
>>> santiago.i...@gmail.com> wrote:
>>>
 Because the exceding generation is supplied by the swing bus. Normal
 power flow does not check power generation limits.
 El 17 feb. 2016 1:58 PM, "Bai, Wenlei" 
 escribió:

> Dear Ray,
>
> I tried to modified load of ‘case9’ to exceed the total generation
> capacity purposely.
>
> To my surprise, power flow still converges.  More specifically,  the
> total generator ‘on-line capacity’ is 820MW, while the ‘actual generation’
> is 920.8MW
>
> Why the actual generation can be larger than its capacity?
>
>
>
> Blessings,
> Wenlei
>
>
>

>>>
>>
>

Re: power flow question

[Jovan Ilic]

Jose,

I did not suggest to turn the swing bus into a PV bus. There should be at
least one swing bus
in the system unless you formulate your PF problem as ACOPF problem which
does not need
any slack buses.

I understand what you are saying and you are right. I'd keep the swing bus
as it is just
to provide the angle reference (admittance matrix is rarely singular) and
add to Jacobian a
constraint on the sum of P and Q flows on the lines connected to the swing
bus.  The sum
of all these lines out flows must be less than the power injection
capability of the swing bus,
both P and Q. If the constraint is violated the power flow does not
converge. The original
poster was concerned with the convergence when there is not enough
generation, so
no convergence would give them a really stern "warning" and leave them
guessing what went
wrong.  Or you can just keep it simple and have PF implementation just
print out a warning
that the slack bus exceeded its capacity.  Modifying the Jacobian was the
first thing that
came to my mind but I am not sure if it provides anything in addition of a
warning to user.

Jovan


On Thu, Feb 18, 2016 at 3:25 AM, Jose Luis Marin 
wrote:

> But you did that, it would no longer be a powerflow calculation.  There
> are good mathematical reasons why the standard powerflow calculation is
> formulated so that there should be at least one swing bus (where you
> specify both V and A, leaving P and Q "free").  If you specified V, A, and
> Pgen at the swing, this would yield an overdetermined system.  You could
> theoretically formulate a powerflow in which the swing bus specified only A
> (the global angle reference) and Pgen, leaving Vref and Qgen free, but this
> would yield a system of equations with a severe pathology, namely a
> near-singular Jacobian (this originates from the fact that the full
> transmission admittance matrix, being a Laplacian matrix, always has a zero
> eigenvalue, which corresponds to a translation symmetry consisting in
> uniformly shifting all voltages;  pinning down at least one voltage is what
> breaks this symmetry and recovers invertibility).
>
> However, I think you're right it would be a good idea to *warn* the user
> when the swing generator(s) have gone over their PMAX (or below their
> PMIN!).
>
> --
> Jose L. Marin
> Grupo AIA
>
>
> On Thu, Feb 18, 2016 at 12:08 AM, Jovan Ilic  wrote:
>
>>
>> Good point, maybe we should trow a Pgen constraint on the swing buses in
>> the Jacobian.
>>
>>
>>
>> On Wed, Feb 17, 2016 at 5:30 PM, Santiago Torres > > wrote:
>>
>>> Because the exceding generation is supplied by the swing bus. Normal
>>> power flow does not check power generation limits.
>>> El 17 feb. 2016 1:58 PM, "Bai, Wenlei"  escribió:
>>>
 Dear Ray,

 I tried to modified load of ‘case9’ to exceed the total generation
 capacity purposely.

 To my surprise, power flow still converges.  More specifically,  the
 total generator ‘on-line capacity’ is 820MW, while the ‘actual generation’
 is 920.8MW

 Why the actual generation can be larger than its capacity?



 Blessings,
 Wenlei



>>>
>>
>

Re: power flow question

[Jose Luis Marin]

But you did that, it would no longer be a powerflow calculation.  There are
good mathematical reasons why the standard powerflow calculation is
formulated so that there should be at least one swing bus (where you
specify both V and A, leaving P and Q "free").  If you specified V, A, and
Pgen at the swing, this would yield an overdetermined system.  You could
theoretically formulate a powerflow in which the swing bus specified only A
(the global angle reference) and Pgen, leaving Vref and Qgen free, but this
would yield a system of equations with a severe pathology, namely a
near-singular Jacobian (this originates from the fact that the full
transmission admittance matrix, being a Laplacian matrix, always has a zero
eigenvalue, which corresponds to a translation symmetry consisting in
uniformly shifting all voltages;  pinning down at least one voltage is what
breaks this symmetry and recovers invertibility).

However, I think you're right it would be a good idea to *warn* the user
when the swing generator(s) have gone over their PMAX (or below their
PMIN!).

-- 
Jose L. Marin
Grupo AIA


On Thu, Feb 18, 2016 at 12:08 AM, Jovan Ilic  wrote:

>
> Good point, maybe we should trow a Pgen constraint on the swing buses in
> the Jacobian.
>
>
>
> On Wed, Feb 17, 2016 at 5:30 PM, Santiago Torres 
> wrote:
>
>> Because the exceding generation is supplied by the swing bus. Normal
>> power flow does not check power generation limits.
>> El 17 feb. 2016 1:58 PM, "Bai, Wenlei"  escribió:
>>
>>> Dear Ray,
>>>
>>> I tried to modified load of ‘case9’ to exceed the total generation
>>> capacity purposely.
>>>
>>> To my surprise, power flow still converges.  More specifically,  the
>>> total generator ‘on-line capacity’ is 820MW, while the ‘actual generation’
>>> is 920.8MW
>>>
>>> Why the actual generation can be larger than its capacity?
>>>
>>>
>>>
>>> Blessings,
>>> Wenlei
>>>
>>>
>>>
>>
>

Re: power flow question

[Jovan Ilic]

Good point, maybe we should trow a Pgen constraint on the swing buses in
the Jacobian.



On Wed, Feb 17, 2016 at 5:30 PM, Santiago Torres 
wrote:

> Because the exceding generation is supplied by the swing bus. Normal power
> flow does not check power generation limits.
> El 17 feb. 2016 1:58 PM, "Bai, Wenlei"  escribió:
>
>> Dear Ray,
>>
>> I tried to modified load of ‘case9’ to exceed the total generation
>> capacity purposely.
>>
>> To my surprise, power flow still converges.  More specifically,  the
>> total generator ‘on-line capacity’ is 820MW, while the ‘actual generation’
>> is 920.8MW
>>
>> Why the actual generation can be larger than its capacity?
>>
>>
>>
>> Blessings,
>> Wenlei
>>
>>
>>
>

Re: power flow question

[Santiago Torres]

Because the exceding generation is supplied by the swing bus. Normal power
flow does not check power generation limits.
El 17 feb. 2016 1:58 PM, "Bai, Wenlei"  escribió:

> Dear Ray,
>
> I tried to modified load of ‘case9’ to exceed the total generation
> capacity purposely.
>
> To my surprise, power flow still converges.  More specifically,  the total
> generator ‘on-line capacity’ is 820MW, while the ‘actual generation’ is
> 920.8MW
>
> Why the actual generation can be larger than its capacity?
>
>
>
> Blessings,
> Wenlei
>
>
>

Re: power flow question

[Abhyankar, Shrirang G.]

Wenlei,
  The power flow routine in MATPOWER does not enforce generation limits on real 
power. Exceeding the capacity does not necessarily imply a divergence of the 
power flow.

Shri

From: , Wenlei <wenlei_...@baylor.edu<mailto:wenlei_...@baylor.edu>>
Reply-To: MATPOWER discussion forum 
<matpowe...@list.cornell.edu<mailto:matpowe...@list.cornell.edu>>
List-Post: matpower-l@cornell.edu
Date: Wednesday, February 17, 2016 at 12:57 PM
To: "matpower-l@cornell.edu<mailto:matpower-l@cornell.edu>" 
<matpower-l@cornell.edu<mailto:matpower-l@cornell.edu>>
Subject: power flow question

Dear Ray,
I tried to modified load of ‘case9’ to exceed the total generation capacity 
purposely.
To my surprise, power flow still converges.  More specifically,  the total 
generator ‘on-line capacity’ is 820MW, while the ‘actual generation’ is 920.8MW
Why the actual generation can be larger than its capacity?

Blessings,
Wenlei

power flow question

[Bai, Wenlei]

Dear Ray,
I tried to modified load of 'case9' to exceed the total generation capacity 
purposely.
To my surprise, power flow still converges.  More specifically,  the total 
generator 'on-line capacity' is 820MW, while the 'actual generation' is 920.8MW
Why the actual generation can be larger than its capacity?

Blessings,
Wenlei