Mr.Cool
Advanced Member level 2
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inverter synchronization
hello everyone. i am currently designing a Photovoltaic inverter for residential use. i was wondering if there are any people out there that can provide some advice?
currently, i am using a full H-bridge, single phase inverter. it connects to the grid via a single inductor (not an active filter). i am using analog method to generate the gate functions (compare a triangle wave to the sine wave from the grid). between the solar panal and the inverter lies a Maximum Power Point Tracker (MPPT) to force the solar panel to produce its maximum power. (more on this later).
my questions are, how can i ensure that power flows from my inverter to the Grid at ALL TIMES ?
what i have come up with so far is to force the phase of the current to be at unity power factor by adjusting the voltage phase angle.
the forumula looks like:
I*(phase_angle) = Vinverter*(inv.phase_angle) - Vgrid*(0)
--------------------------------------------
Z(90degrees)
note that the grid phase angle is taken as the reference and is hence equal to 0. The Z (impedance) of the inductor is 90 degrees (or is that -90?). Thus, the phase angle of the inverter voltage can be adusted to control unity power factor.
is it true taht power will ALWAYS flow from inverter to Grid so long as the magnitue of the inverter output voltage is ALWAYS greater than the grid voltage? or is there some other method?
my second question, since my solar panals will produce a varying DC supply to the inverter how do i make my inverter "immune" to a varying DC supply? a varying DC supply will cause lower order harmonics which must be avoided. i do not want to use a regulator at the output of the solar panal as i believe this is a waste of power dissipation. any suggestions?
thanks for any help
Mr.Cool
hello everyone. i am currently designing a Photovoltaic inverter for residential use. i was wondering if there are any people out there that can provide some advice?
currently, i am using a full H-bridge, single phase inverter. it connects to the grid via a single inductor (not an active filter). i am using analog method to generate the gate functions (compare a triangle wave to the sine wave from the grid). between the solar panal and the inverter lies a Maximum Power Point Tracker (MPPT) to force the solar panel to produce its maximum power. (more on this later).
my questions are, how can i ensure that power flows from my inverter to the Grid at ALL TIMES ?
what i have come up with so far is to force the phase of the current to be at unity power factor by adjusting the voltage phase angle.
the forumula looks like:
I*(phase_angle) = Vinverter*(inv.phase_angle) - Vgrid*(0)
--------------------------------------------
Z(90degrees)
note that the grid phase angle is taken as the reference and is hence equal to 0. The Z (impedance) of the inductor is 90 degrees (or is that -90?). Thus, the phase angle of the inverter voltage can be adusted to control unity power factor.
is it true taht power will ALWAYS flow from inverter to Grid so long as the magnitue of the inverter output voltage is ALWAYS greater than the grid voltage? or is there some other method?
my second question, since my solar panals will produce a varying DC supply to the inverter how do i make my inverter "immune" to a varying DC supply? a varying DC supply will cause lower order harmonics which must be avoided. i do not want to use a regulator at the output of the solar panal as i believe this is a waste of power dissipation. any suggestions?
thanks for any help
Mr.Cool