Inverter with inductors and capacitors

Jpflex

Jpflex

Electrician big leagues
Location
Victorville
Occupation
Electrician commercial and residential
At the power production plant I’m currently working at, we have 1500 Vdc solar array input to large inverters with output at 43,500 volts ac supplied to grid.

From the field strings 1,500 Vdc input before the individual inverters and before the dc disconnects, there are what is called choke inductors. Supposedly this is to mitigate the adverse affects of dc pulses but I was wandering if someone here could explain the purpose and theory of these better

Additionally there is a notch inductor and capacitor bank following the 690 volts AC output of the individual inverters. I assume this is to improve power factor and or signal wave or perhaps someone here could explain this better or add to this?

After the 690 volts AC out from the inverters, voltage is stepped up to 43,500 volts AC which must match the grids frequency, voltage and waveform. My third question to this is whether a slight deviation on inverter voltage output to the grid voltage could cause what would be an inrush current or similar to short circuit from the difference of voltage potential? Also how is the frequency and wave form matched to grid?
 
I'm going to attempt to answer some of them but I have not personally designed or reviewed this type of setup. I am just pulling from my old college days.

The choke inductor is going to "stop" Higher frequencies from appearing on the DC lines.

"notch" filter is like a stop band and cuts off a specific frequency from continuing. I don't know if that is the same for notch inductor/capacitor bank.

Voltage Deviation can cause the inverters to disengage (over voltage / undervoltage) if it exceeds thresholds. Those thresholds can be based on engineering concern or equipment specifications. Voltage deviations can cause voltage waveform distortions but if they are small, then it shouldn't matter. When you think of a skyscraper, a small AC unit on the roof isn't really changing the height of the building.

Electronics can use different methods to match frequency. One of the more modern/common is a phase lock loop. You can also design a oscillator to the desired frequency but having the output follow the input (phase lock loop) is probably the best method in this circumstance.

Filters can be complicated but you will just be interested in simple low pass / band stop / notch filters if you were going to look more into it.

Capacitors and inductors can also be used to smooth waveforms and help correct unwanted ripples and other forms of distortion based on the application.
 
Jpflex said:
At the power production plant I’m currently working at, we have 1500 Vdc solar array input to large inverters with output at 43,500 volts ac supplied to grid.

From the field strings 1,500 Vdc input before the individual inverters and before the dc disconnects, there are what is called choke inductors. Supposedly this is to mitigate the adverse affects of dc pulses but I was wandering if someone here could explain the purpose and theory of these better

Additionally there is a notch inductor and capacitor bank following the 690 volts AC output of the individual inverters. I assume this is to improve power factor and or signal wave or perhaps someone here could explain this better or add to this?

After the 690 volts AC out from the inverters, voltage is stepped up to 43,500 volts AC which must match the grids frequency, voltage and waveform. My third question to this is whether a slight deviation on inverter voltage output to the grid voltage could cause what would be an inrush current or similar to short circuit from the difference of voltage potential? Also how is the frequency and wave form matched to grid?
Click to expand...
Victorville solar I've heard about is a sterling engine concentrator system, not photovoltaic.
Is that the system you are working??

Need details. dc inductors from a photovoltaic array have differenet function than inductors between if variable frequency generator and inverters.
Please provide some details on the type system you are working with.
 
Jpflex said:
After the 690 volts AC out from the inverters, voltage is stepped up to 43,500 volts AC which must match the grids frequency, voltage and waveform. My third question to this is whether a slight deviation on inverter voltage output to the grid voltage could cause what would be an inrush current or similar to short circuit from the difference of voltage potential? Also how is the frequency and wave form matched to grid?
Click to expand...
A grid tied inverter matches the voltage and frequency that it sees on its output terminals; it cannot make changes to those parameters on its own.
 
I don't know a lot about grid inverters but I do have some experience designing and building a low frequency battery inverter for my personal use. The choke on the transformer primary does two things: It helps slow the rate of change of the current through the winding as the core approaches saturation to keep the MOSFETs from exploding, and it blocks the high frequency noise from the switching section.
 
I'm sure I know nothing about the latest developments in utility scale solar but I'm a bit surprised that what the OP is describing isn't all contained in the inverters. Unless he is describing putting together a modular central inverter assembly.
 
junkhound said:
Victorville solar I've heard about is a sterling engine concentrator system, not photovoltaic.
Is that the system you are working??

Need details. dc inductors from a photovoltaic array have differenet function than inductors between if variable frequency generator and inverters.
Please provide some details on the type system you are working with.
Click to expand...
No actually I’m working at a power production plant not in Victorville. Solar arrays feed inverters to bess battery systems and or just an inverter to inject 43,500 volts ac into the grid
 
GoldDigger said:
Just a guess that the notch filter is to suppress third harmonic.
Click to expand...
I believe your correct as there is an inductor choke on dc side and notch inductor on ac side after the inverter

The inductor on the dc side has something to do with dc pulses
 
jaggedben said:
I'm sure I know nothing about the latest developments in utility scale solar but I'm a bit surprised that what the OP is describing isn't all contained in the inverters. Unless he is describing putting together a modular central inverter assembly.
Click to expand...
Inverters are pre assembled but I was just trying to get more understanding on theory for purpose and operation of some components within
 
electrofelon said:
Just a comment on the 43.5KV. Seems like an odd voltage in "no mans land" between 35KV and 69KV. Not sure if I've ever heard of a system voltage between those two.
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But it really is 43,500 V AC at the MV transformer output to the grid. I’m not working at the mine in the middle of nowhere anymore. The mine lost its investor funding and went out of business. I’m currently working for a power production plant
 
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