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How to calculate the best load shedding bus?

asked 2018-04-05 20:55:58 -0600

Linzhi gravatar image

Hi, all. AC power flow calculation can be unsolvable due to lose of the operating point.

I want to identify the bus where to shed load to take back the operation point, and try to leverage the eigenvalues of Jacobian matrix. However, I cannot find the way to use them. What python API to retrieve the eigenvalues?

I looked up the forum and found only this answer: psspy.org/psse-help-forum/question/1487/how-to-do-cascading-failure-simulation/. The user Rounak said to calculate Load Shift Factor based on the entries of the LSF matrix, what are they?

Thank you!

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answered 2018-04-06 09:34:23 -0600

jconto gravatar image

Assuming you already decided that load shedding is the solution to the problem (instead or in addition to reactive compensation, new transmission lines, etc.), then I suggest to re-study the network such that the non-convergence state is reached but incrementally. A voltage stability study would identify contingencies that collapse the network at some incremental power transfer.

In PSSe there is no API function to provide eigenvalues of the Jacobian matrix but by monitoring the voltage decrease at buses as the network reaches its singular point, a severely impacted region can be identified, then it can be said that the load in that region is good candidate for load shedding. Tools like the "fast voltage stability index" can be easily coded in python to get a list of weak buses in the base case. The ACCC, n-1-1 and 'AC Corrective Actions' activities can calculate load shedding under contingency to resolve the non-convergence state.

Tools like VSAT can analyze the network to find 'voltage collapse' conditions and provide a list of participating buses after a modal analysis run. Loads in those buses are candidates for load shedding.

Next, a dynamic simulation using under voltage load shedding relays would verify the effectiveness of the 'UVLS' schema, with appropriate load fraction and time delays, such the voltage collapse does not occur under contingency.

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Thank you very much! Jose. I will carefully study the tools you recommended. If possible, I would like to ask for your help here in further uses. Thanks again!

Linzhi gravatar imageLinzhi ( 2018-04-06 21:33:38 -0600 )edit

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Asked: 2018-04-05 20:55:58 -0600

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Last updated: Apr 06 '18