How to specify pw_mw for ext_grid

[angrysnail]

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Issue

I want to hold a specified value for ext_grid, by adjusting the pcs, pvs, even the load。 But the load, sgen, storage in pandapower， all need to specify a p_mw value, then after runpp(), the ext_grid p_mw value will be changed even I set ext_grid's controllable=False. Any suggestion?

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[pawellytaev]

In power flow analysis, the ext_grid automatically adjusts to balance the total generation and load in the network, since it acts as an infinite bus. You set a voltage and as a result you get the results P&Q. To maintain a specified ext_grid value, you need a control strategy that adjusts the power of other elements (loads, PVs, storage) dynamically. As you can see in the doc for ext_grid https://pandapower.readthedocs.io/en/latest/elements/ext_grid.html , the max_p_mw and min_p_mw are only considered in OPF