General Question:
Assume, a microgrid is connected to a utility grid though a transmission line. The microgrid imports power from the utility grid though a controlled device which regulate the power flow. The balanced system has 50 Hz of frequency.
Now assume that in the microgrid, sum of the generation and import becomes higher than the total consumption. As a result the frequency of the microgrid increases to 51 Hz. Thus, is it possible that the frequency of the utility grid remains 50 Hz and sends power to the microgrid which has a frequency of 51 Hz. Is there any such control device that can be used in the transmission line that can make it happen?
1) Two buses can have different frequencies if it's connected through a dc link.
2) The power flow oscillates if you try to send power from system with one frequency to another system with different frequency.
Hi Hasan, if there is no demand of power at the microgrid end, it is not clear to me how the power travels from the grid to the microgrid. I mean, could you please make a circuit diagram and show how KCL is not violated in what you are proposing ?
If the two AC buses with different frequency are connected through a DC link as Samundra has stated, then it is possible to send power from any bus to the other. If the AC buses are 3-phase, the power on DC will be steady, but there will be lower order harmonic current ripples generated on the dc line due to interaction between the reflected AC supply frequency from two sides being different.
If the two AC buses with different frequency are connected directly, large circulating currents will flow, limited by the impedance of line and source, due to mismatch of frequency at both sides.
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