Power grid with changeable frequency without the phasor simulation mode

Hi there,

I was just wondering. Are there any options to mimic the behaviour of a power grid with variable (changeable) frequency? In general, power grids can be modelled by employing a three-phase source block and some others with the similar functionality. It is possible to specify the voltage, phase, frequency and harmonics orders, but the frequency is not changeable. In the sense that when there is a sudden increase/drop in load/generation in the power grid, it does not cause any frequency changes. So, by and large the grid frequency is specified by its block, rather than the network and generation units connected to the grid (in terms of its variation). In the topic:

https://au.mathworks.com/matlabcentral/answers/113868-power-grid-with-changeable-frequency

It is mentioned that it is possible to use the phasor mode of simulation in order to get the desired behaviour, but I does not seem that it works in fact. Both (generator and power grid) are in the swing mode as well and the generator’s parameters are tuned via the powergui. I definitely don’t want to model the power grid as a synchronous generator (I reckon the load changes will reflect the frequency), so what kind of options do I have here? Thank you in advance.

Answer 1

[Joel Van Sickel]

Hello Efim,

you can certainly simulate the line frequency changing. Certain blocks, to stay simple, only support a fixed frequency, but you can create your own controlled three phase source and apply any signals you want. You can simulate completely unbalanced systems with arbitrary waveforms and even have different frequencies per phase. However, phasor simulation only works for a fixed frequency, so you will have to use continuous or fixed step models for this type of simulation.

One easy way to start, would be to simulate a motor as a generator, and increase it's speejd. This will increase the line frequency and you can see how the system responds.

Regards,

Joel

[Milica Bogdanovic]

Can you please make component of a three-phase programmable voltage source that we can use in power systems with variable frequency (frequency as an input). Thanks a lot in advance!