3~Phase Inverter control--Grid

[biro34]

Helloo to all
Have a question about 3 phase inverter control..
especially about voltage control, current control, and Active (P)+reactive (Q) Control
There are many articel about this control type, but can you guys give a simplier explanaiton?

i think if i want to control p and q, i have to control the Current -but to do this i have to change the PWM Signal, so i would also change the voltage right?





lets have 3 Types of operations:

1. Inverter in islanding mode ...lets say, smal village powered from 1 Inverter
Wich type of control does it need?
is it possible to control active and reactive power?
i think not,
because the load would get himself what he need dependig on his impedance.-
i think only voltag foward control is the right one , yes ?
Because the inverter should hold the Voltage contant , and the loads are going to get the current they need, right?


2. 1. Inverter in islanding mode ...lets say, smal village powered from 2 Inverter..
Wich type of control does it need?
P-Q control would be possible to divide the needed powerto the two inverters..
but this needs a current control..and to control the current , we have to control the voltage, right?

2. 1. Inverter in gried tie mode ...lets say 1 Inverter and 1 grid connected
in this case the inverter could be controlled as P-Q control right?
cause the inverter could inject P and Q as set in to the grid.
but to do this, we also have to control the current and to do this we have to control the voltage , right?

so the realy''only'' thing they change is primary the output voltage right?
or is it possible to change the inverter output current without changing the voltage?

Thankss

 

[summitville]

Scenario #1 - A single Inverter, No Grid
Voltage & Frequency control, just like a UPS
There is no "Grid-Tie" action here

Scenario #2 - Two Inverters, No Grid
a) One Master ( Frequency & Voltage ) and one Slave ( Grid-Tie mode ) or
b) Both are Masters

Load Sharing ...
1) Load Sharing via communications
2) Load Sharing using the Droop Method
3) Load Sharing using Frequency Shift
4) Load Sharing using <other>

The Phase Angle between the two Inverters needs to be kept to a minimum
Many trade-offs with voltage & frequency regulation

Scenario #3 - One Inverter with an Active Grid
a) Grid-Tie Mode - The Inverter acts like an AC Current Source into the Grid