for conventional droop control, when microgrid is in islanded mode and several DG work in parallel. for simulation, How to translate the variables from an individual inverter reference frame onto the common frame?
Hi Parisa,
The d-q reference frames can be transformed between each other by the well known transformation matrix:
[ cos theta sin theta ]
[ -sin theta cos theta ]
where theta (fixed or time varying) is the angle between the d-axes of the two reference frames.
Iman and Somesh have pretty much summed up the basic concepts. I may just add that though by and large one sticks to a common reference frame for convenience of control and power flow, this is not absolutely necessary !
Depending on the control requirement, speed of response, and the degree of unbalance each of them have to handle, individual inverters can be operated on different reference frames - these being converted to a common one for power flow considerations.
-Sanjay
In my idea, the control system of each DG unit can be implemented in different reference frames. The reference frame of control system is selected based on your requirements. Each reference frame has its advantages; e.g., the synchronous reference frame provides zero steady-state error using the PI controllers while its performance is degraded during unbalanced conditions. However, you can transform variables using Park and Clarke transformations.
Hi Parisa,
The d-q reference frames can be transformed between each other by the well known transformation matrix:
[ cos theta sin theta ]
[ -sin theta cos theta ]
where theta (fixed or time varying) is the angle between the d-axes of the two reference frames.
Iman and Somesh have pretty much summed up the basic concepts. I may just add that though by and large one sticks to a common reference frame for convenience of control and power flow, this is not absolutely necessary !
Depending on the control requirement, speed of response, and the degree of unbalance each of them have to handle, individual inverters can be operated on different reference frames - these being converted to a common one for power flow considerations.
-Sanjay
Dear Parisa,
Refer this link
http://ieeexplore.ieee.org/ielx7/59/6740879/06655978.pdf?tp=&arnumber=6655978&isnumber=6740879
Salam, It depends and determined specifically for every different case, Some times you need to have a same reference e.g in PMS applications
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