For power flow, MATPOWER simply solves the problem as specified (with the
specified load and generation values) with all imbalances handled by the slack
generator. If you want re-dispatching to be done to maintain balance you may
want to use an OPF. With an OPF, dispatchable loads can be used to model
automatic shedding of load under shortage conditions.
Ray
> On May 1, 2019, at 4:18 PM, Dennis, Mitchell T. <[email protected]>
> wrote:
>
> Shri,
>
> Thank you for your response.
>
> If a network, after removing nodes, requires more power than can be provided,
> does MATPOWER automatically shed the load necessary to balance the equations?
> Similarly, if a network is producing too much power for a network after
> removing nodes, will MATPOWER reduce the power generated?
>
> Best Regards,
> Mitchell T Dennis
>
> From: [email protected]
> <mailto:[email protected]>
> <[email protected]
> <mailto:[email protected]>> on behalf of Abhyankar,
> Shrirang G <[email protected] <mailto:[email protected]>>
> Sent: Monday, April 29, 2019 11:53:44 AM
> To: MATPOWER discussion forum; [email protected]
> <mailto:[email protected]>
> Subject: Re: Removing a Bus and Evaluating the New Network
>
> Mitchell,
> See below.
>
> Shri
>
> From: <[email protected]
> <mailto:[email protected]>> on behalf of "Dennis,
> Mitchell T." <[email protected] <mailto:[email protected]>>
> Reply-To: MATPOWER discussion forum <[email protected]
> <mailto:[email protected]>>
> Date: Friday, April 26, 2019 at 8:38 PM
> To: "[email protected] <mailto:[email protected]>"
> <[email protected] <mailto:[email protected]>>
> Subject: Removing a Bus and Evaluating the New Network
>
> Dear All,
>
> I have a question regarding convergence.
>
> I am attempting see the effect of removing a node on a power network using
> MATPOWER.
>
> To do this, I first evaluate the IEEE case with 300 nodes, and then I set the
> branches of one of the nodes to zero.
>
> All isolated nodes (buses) should have bus type = 4. You can find which nodes
> are isolated and the islands formed using the function find_islands
> <https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.pserc.cornell.edu%2Fmatpower%2Fdocs%2Fref%2Fmatpower5.0%2Ffind_islands.html&data=02%7C01%7Cmitchelldennis716%40uky.edu%7C526c412f8ee84e0303dd08d6ccbb0979%7C2b30530b69b64457b818481cb53d42ae%7C0%7C0%7C636921501027621070&sdata=lFg1cnNTjvFT51KF9bkZy69nxRLsvEBs5fNkuxBpO7I%3D&reserved=0>.
>
> Doing this typically causes the network to no longer converge using the power
> flow equations, however in some cases it will still converge.
>
> It’s highly unlikely that the power flow converges if there are isolated
> buses in the network. You might want to run the find_islands function to see
> if the network is connected or split.
>
> In an attempt to make the diverging networks converge again, I systemically
> reduce the load by setting the bus Pd and Qd values 5% lower and then run the
> convergence test again.
>
> Is there a better way to do this? Am I actually decreasing the load?
>
> You can use MATPOWER’s continuation power flow (see the chapter in the
> manual) instead.
>
> And will decreasing the load make the equations more likely to converge?
>
> Also, how can I tell what is making the equations not converge? Is divergence
> only caused by a load imbalance where the load is too high?
>
> See this FAQ
> <https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.pserc.cornell.edu%2Fmatpower%2F%23pfconvergence&data=02%7C01%7Cmitchelldennis716%40uky.edu%7C526c412f8ee84e0303dd08d6ccbb0979%7C2b30530b69b64457b818481cb53d42ae%7C0%7C0%7C636921501027631074&sdata=zNNIQVwK4lIh6yIk%2BUcoh%2FTNHfph6dw9NCRgX5fAyVI%3D&reserved=0>
> on reasons a power flow may diverge and suggestions to try to make it
> converge.
>
> Thanks in advance
>
> Best Regards,
> Mitchell T Dennis
