Sir
So I used the toggle_myconstraints method you had suggested to add Voltage
angle constraints to the problem. After getting the solution, I update the
constraints set and call toggle_myconstraints again. But this time, I get
an error :
Caused by:
Error using add_userfcn (line 119)
add_userfcn: the function 'userfcn_myconstraints_formulation' has
already been added
How do I avoid this problem? Is there a way to overwrite what's already
written in both add_userfcn and the linear constraints section in om (in
this case 'Va')?
Regards
Viswanath
On Fri, Oct 13, 2017 at 10:04 AM, Viswanath Hariharan <[email protected]>
wrote:
> Thank you for your help sir. I think I was doing something wrong. It works
> alright now.
>
> Regards
> Viswanath
>
> On Oct 12, 2017 10:03 AM, "Ray Zimmerman" <[email protected]> wrote:
>
>> Are you saying that your solution includes voltage angles whose absolute
>> value is greater than 0.26 radians or 14.9 degrees?
>>
>> Ray
>>
>>
>> On Oct 11, 2017, at 8:52 PM, Viswanath Hariharan <[email protected]>
>> wrote:
>>
>> First, thank you so much for your time, Sir.
>> So I tried the first approach first. I want to added box constraints for
>> Voltage angle, -0.26 < theta < 0.26. I created the A matrix and l and u
>> vectors and passed it to the opf function. The solution converged and I did
>> get results. But the problem is that the added constraints look like they
>> had no effect on the result.
>>
>> I also tried the toggle_reserves() method you suggested in the previous
>> email of this thread where you asked me rename toggle_reserves and all the
>> callback functions within it and modify its contents to toggle the addition
>> of constraints. I did that too. results = runopf(mpc) and results.om had
>> 5 linear constraints added to it. But again this had no effect on the
>> results. I even tried changing the bounds to see if there was any
>> difference but there wasn't.
>>
>> What is it that I'm missing out here?
>>
>> Regards
>> Viswanath
>>
>>
>>
>> On Tue, Oct 10, 2017 at 9:09 AM, Ray Zimmerman <[email protected]> wrote:
>>
>>> It appears you have fundamentally misunderstood callback functions and
>>> how they work. I suggest that you read carefully the entirety of sections
>>> 7.2–7.5 in the User’s Manual and make sure you understand the
>>> toggle_reserves() example used to illustrate the approach.
>>>
>>> To implement your own constraints, I would recommend copying and
>>> renaming toggle_reserves() to something like toggle_myconstraints().
>>> Then rename all of the callback functions defined in that file to e.g.
>>> userfcn_myconstraints_ext2int(), userfcn_myconstraints_formulation(),
>>> etc., and modify their contents to reflect the constraints you want to add
>>> (as opposed to those implemented for the zonal reserves case). The
>>> “formulation” callback is where you’ll be calling add_constraints().
>>> Then you can simply toggle your constraints on and use runopf()
>>> normally.
>>>
>>> mpc = loadcase('<mycase>');
>>> mpc = toggle_myconstraints(mpc, 'on');
>>> results = runopf(mpc);
>>>
>>> Hope this helps,
>>>
>>> Ray
>>>
>>>
>>>
>>> On Oct 5, 2017, at 12:18 PM, Viswanath Hariharan <[email protected]>
>>> wrote:
>>>
>>> Sir
>>>
>>> I tried adding constraints using the callback functions method described
>>> in Section 7.2 but I am not sure I followed it correctly.
>>> mpopt = mpoption;
>>> om = opf_setup(mpc, mpopt);
>>> om = add_constraints(om, 'Vm', A1, l1, u1);
>>> om = add_constraints(om, 'Va', A2, l2, u2);
>>> mpc = get_mpc(om)
>>> results2 = runopf(mpc);
>>>
>>> om gets updated with 10 linear constraints (case5 is being used here).
>>> But mpc doesn't get updated and hence when I run this code and check and
>>> results.var.mu.l.Va <http://results.var.mu.l.va/>, the constraints
>>> aren't updated. Not only that, the mpc file isn't getting updated as well.
>>> I think I am making some mistake with this line : mpc = get_mpc(om) because
>>> om is fine. What am I missing here? Or should I take another approach?
>>> Thank you so much for your time Sir.
>>>
>>> Regards
>>> Viswanath Hariharan
>>>
>>> On Thu, Oct 5, 2017 at 10:27 AM, Ray Zimmerman <[email protected]> wrote:
>>>
>>>> You only need to use the add_constraints() function if you are using
>>>> Callback Functions as described in Section 7.2 as opposed to Direct
>>>> Specification as described in Section 7.1 of the User’s Manual
>>>> <http://www.pserc.cornell.edu/matpower/docs/MATPOWER-manual-6.0.pdf>.
>>>>
>>>> You convergence failure my just imply that your variable bounds are
>>>> tight enough that there is no feasible solution. Try relaxing the limits
>>>> and see if it converges.
>>>>
>>>> Vm, Pg and Qg all have limits specified directly in the bus and gen
>>>> matrices. Vm is bounded by the VMIN and VMAX columns in the bus matrix.
>>>> Pg and Qg are bounded by the PMIN, PMAX and QMIN, QMAX columns of the
>>>> gen matrix, respectively. Va is not normally constrained (except at
>>>> the reference bus), so the bus matrix doesn’t contain bounds for it. In
>>>> that case, you have to use the standard linear constraints of equation
>>>> (6.25) to impose bounds.
>>>>
>>>> At a lower lever, variable bounds are defined when variables are added
>>>> via the add_vars() method. The Va, Vm, Pg and Qg variables are added
>>>> automatically (with their bounds) in opf_setup(), so you can’t really
>>>> modify them there. But for any variables you add later, you supply the
>>>> bounds when you call add_vars().
>>>>
>>>> Ray
>>>>
>>>>
>>>>
>>>> On Oct 4, 2017, at 3:52 PM, Viswanath Hariharan <[email protected]>
>>>> wrote:
>>>>
>>>> So I do not need to use the add_constraints function? Because when I
>>>> used the code you mentioned and then runopf(mpc), convergence fails. In
>>>> general, how to add box constraints for Va,Vm, Pg and Qg of xr (r =
>>>> runopf(mpc); r.raw.xr).
>>>> If I have to use the add_constraints function, how do I do that?
>>>>
>>>> Regards
>>>> Viswanath Hariharan
>>>>
>>>> On Wed, Sep 27, 2017 at 1:39 PM, Ray Zimmerman <[email protected]>
>>>> wrote:
>>>>
>>>>> Voltage magnitude constraints are already included. Simply set the
>>>>> VMIN and VMAX columns in the bus matrix to the desired values.
>>>>>
>>>>> For voltage angles, simply define the A, l and u corresponding to
>>>>> equation (6.25) in the User’s Manual
>>>>> <http://www.pserc.cornell.edu/matpower/docs/MATPOWER-manual-6.0.pdf>.
>>>>> Something like the following …
>>>>>
>>>>> mpc = loadcase(<your-case-name>);
>>>>> nb = size(mpc.bus, 1);
>>>>> ng = size(mpc.gen, 1);
>>>>> mpc.A = sparse(1:nb, 1:nb, 1, nb
>>>>> <https://maps.google.com/?q=1:nb,+1,+nb&entry=gmail&source=g>,
>>>>> 2*nb+2*ng);
>>>>> mpc.u = 0.26 * ones(nb, 1);
>>>>> mpc.u = -mpc.l;
>>>>>
>>>>> — Ray
>>>>>
>>>>>
>>>>>
>>>>> On Sep 23, 2017, at 5:25 PM, Viswanath Hariharan <[email protected]>
>>>>> wrote:
>>>>>
>>>>> Hello Sir
>>>>>
>>>>> I want to add voltage magnitude and voltage angle constraints to the
>>>>> opf solver but I am not able to figure out how to.
>>>>>
>>>>> Voltage magnitude constraints ---> 0.9 <= Vm <= 1.1
>>>>> Voltage angle constraints ---> - 0.26 <= Va <= 0.26 (Unrelaxed form)
>>>>>
>>>>> I read a post where you mentioned to add these constraints to the case
>>>>> struct which looked pretty simple in the post but I didn't know how to
>>>>> add
>>>>> that to the case struct.
>>>>> I was wondering if you can guide me on how to do it. Hoping to hear
>>>>> from
>>>>> you soon.
>>>>>
>>>>> Regards
>>>>> Viswanath Hariharan
>>>>> Graduate Research Assistant
>>>>> Electrical Engineering
>>>>> University at Buffalo
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
