Issue on Unbalanced Load Flow on Simscape Power System

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Augusto Janssen Harger da Silva 2020-8-13

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https://ww2.mathworks.cn/matlabcentral/answers/579312-issue-on-unbalanced-load-flow-on-simscape-power-system

评论： Augusto Janssen Harger da Silva 2020-8-27

Everytime that I try to calculate a tri phase load flow on a model that contains a synchronous machine, i get this error on Matlab Command Window: ‘Matrix close to singular or badly scaled’

However, the Balanced Load Flow works perfectly, for the same model.

Any idea how to solve this?

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Joel Van Sickel 2020-8-17

When you say tri phase load flow, do you mean load flow on an unbalanced system? Which load flow tool are you using and can you share your model?

Augusto Janssen Harger da Silva 2020-8-19

unbalancedLF_mg.slx

Ops, sorry, I mistyped... Three phase load flow would be the correct expression. That means I am selecting the parameter "Connectors" to ABC instead of Single in Load Flow Bus Block.

I am using the load flow tool from the powergui block.

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Answer 1

Joel Van Sickel 2020-8-24

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https://ww2.mathworks.cn/matlabcentral/answers/579312-issue-on-unbalanced-load-flow-on-simscape-power-system#answer_484259

power_LFnetwork_5bus_modified.slx

Hello Augusto,

the issue is likely with the model. It is possible that your model is 'stiff' making it hard to simulate. You could try adding snubber resistors to your motor.

This example can be modified to work with unbalanced load flow. https://www.mathworks.com/help/physmod/sps/examples/initializing-a-5-bus-network-with-the-load-flow-tool-of-powergui.html

Here is an file with the model above set up for unbalanced load flow working in 2020a. If you have an older verison you can modify the example to switch it to unbalanced and see it working with a synchronous machine.

Regards,

Joel