By setting the magnitudes of Vin and Vg to be equal, then controlling only delta, you can control both P and Q (P -> sin(delta), Q -> cos(delta). In other words, the power factor simply becomes cot(delta). You cannot increase P w/o affecting Q this way. The proper way to independently control both is to control both delta and the Vinv magnitude: Vinv = (X/Vg)*S, delta = arctan(P/Q), with S = sqrt(P^2+Q^2).
2:05 the inverter voltage is shown as lagging to the grid voltage. I think it should be shifted to the left to show active power being delivered from source to grid.
My understanding is we don't want to provide reactive power, it rather was initially created within the inductive load from the grid power. This "delayed" power can feed back into the grid which is undesired, so we gotta make up for it, absorbing it by Capacitors, storing that energy until released into the next upcoming grid cycle
As per the vector diagram in case of active power feeding to the grid , the inverter voltage is the phasor sum of the Vg and VL and hence its magnitude is greater than Vg . could you clarify ?
Great video! Thanks for sharing. I want to ask, is there any limit to inject reactive power from inverter? Like, we know inverter has a dc-link or dc bus. Is the value of dc bus limit the amount of reactive power injected or absorbed?
Correct, there is two limitations: 1) The DC Bus voltage determines the range of the output voltage. So, for each DC Bus voltage you will have a limitation for the output voltage you can get thus limiting the Power Factor. 2) The rated current of the inverter also plays an important role on this. You can check that on the P-Q curves of the inverter. If the PF is 1.0, then the inverter can provide rated active power, if the PF is 0.80 the active power will be reduced, because the rated current will be shared between active and reactive currents.
Things get complicated when LCL output filter is used instead of a simple inductor. I did some calculations with such a filter that include capacitor damping resistor and inductors parasitic resistance. The active current can be adjusted by a very small phase shift between inverter and grid voltage but the inverter voltage needs to be adjusted also. The problem is that the phase shift needed to change the current fed into the grid is extremely small 0.1-0.5 degree which is impractical and difficult to achieve. I did calculations using complex numbers with typical values of L1 = L2 = 4mH, C = 3uF and capacitor damping resistor 5 Ohm. Inductor parasitic resistance 1Ohm. Maybe I made a mistake ?
Can you explain what happen if angle between Vg and Vinv chenges. For my understanding this always insert reactive power component to the Ig. And the second question: what will be reaction of inverter if for example Vg will increase? Does that mean that in order to maintain PF=const at POI and Vinv-Vg=const, inverter will increase Vinv and inject additional reactiove power to the grid?
Hi Edy, I hope you found the answers to your questions, since I now have the same confusion, and could use some explanation. I will write down my understanding and I'd appreciate it if you could correct me where I am wrong:
Q1: What happens when the angle between Vg and Vinv changes? From my understanding, this always inserts a reactive power component to the Ig. According to the concept (beautifully explained in the video) and power flow formulas, there should only be active power generation in response to the phase difference. But when simulated, the converter produces reactive power as well. I believe the reason is that the more active current flows, the more voltage drop across the impedance, and since (Vinv = Vg + VL), it increases converter voltage which results in reactive power flow.
Q2: What will be the reaction of the inverter if, for example, Vg will increase? Does that mean that to maintain PF=const at POI and Vinv-Vg=const, the inverter will increase Vinv and inject additional reactive power to the grid? Yes, the converter increases its output voltage to the grid level.
By adjusting voltage inverter is compensating grid requirements for reactive power. But inverter can not "push" reactive power to the grin in order to maintain grid voltage as other power sources with excitation do. Can you please explain (or simulate) voltage and frequency operational limits of the inverter? How inverter should behave in island mode of operation?
Thanks for sharing the concept . Is this concept is applicable to both voltage source and current source converter , Is this the method being used in solar inverters ?
Very good explanation and thanks for uploading regular videos. I have a doubt that if we keep inverter voltage less than the grid voltage and the phase of Inverter voltage leads the phase of grid voltage. Will we see active power transfer?
I think the concept will be the same as Synchronous generator , Over excite will same as increase value of Vinv , under excite will same reduce value of Vinv
But this current will be sent to the point of common coupling to mitigate harmonics required by load and full fill load reactive power requirements. Correct??
what will be the condition to import active power or reactive power? my understanding to import active power: Vg magnitude and Vinv magnitude shall be same and Vinv shall lead Vg
@@TechSimulator in Matlab function block, you can write code like in dsp but syntexes are different. For more accurate simulation you can use trigger based system.
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Sir How to genearte Active power send to grid Can make viedo on it
Brilliant video you explained in minutes something I couldn't find online at all.
thanks so much for the video,very clear to our new researchers!!!
Brilliant explanation. Thank you.
By setting the magnitudes of Vin and Vg to be equal, then controlling only delta, you can control both P and Q (P -> sin(delta), Q -> cos(delta). In other words, the power factor simply becomes cot(delta). You cannot increase P w/o affecting Q this way.
The proper way to independently control both is to control both delta and the Vinv magnitude: Vinv = (X/Vg)*S, delta = arctan(P/Q), with S = sqrt(P^2+Q^2).
2:05 the inverter voltage is shown as lagging to the grid voltage. I think it should be shifted to the left to show active power being delivered from source to grid.
Very Good and precise explanation.
what an explanation. great one
Glad you liked it
Awesome video, straight foward and with solid content. Thanks!
Thank you so much...you present the things in very well manner ......
Thank you
Beautifully explained !!!
Thanks brother
This is awesome
Ah.... Expaination visualised... Well explained..
Very good video. Conveys lot of information
Awesome lecture
Thanks and welcome
Beautifully explained. Make more such videos
Thanks brother.
Good one, it's similar to the synchronous generator.
Yes, same concept as synchronous Gen, Over excited same as Vinv more, Unser excited is Vinv less
My understanding is we don't want to provide reactive power, it rather was initially created within the inductive load from the grid power. This "delayed" power can feed back into the grid which is undesired, so we gotta make up for it, absorbing it by Capacitors, storing that energy until released into the next upcoming grid cycle
Exactly. That's my understanding too.
Excellent
As per the vector diagram in case of active power feeding to the grid , the inverter voltage is the phasor sum of the Vg and VL and hence its magnitude is greater than Vg . could you clarify ?
great explanation , question: shan't that Ig be IL so consistently VL will lead IL ?
Useful concept
Great video! Thanks for sharing. I want to ask, is there any limit to inject reactive power from inverter? Like, we know inverter has a dc-link or dc bus. Is the value of dc bus limit the amount of reactive power injected or absorbed?
Correct, there is two limitations: 1) The DC Bus voltage determines the range of the output voltage. So, for each DC Bus voltage you will have a limitation for the output voltage you can get thus limiting the Power Factor. 2) The rated current of the inverter also plays an important role on this. You can check that on the P-Q curves of the inverter. If the PF is 1.0, then the inverter can provide rated active power, if the PF is 0.80 the active power will be reduced, because the rated current will be shared between active and reactive currents.
nice presentation, thanks
Things get complicated when LCL output filter is used instead of a simple inductor. I did some calculations with such a filter that include capacitor damping resistor and inductors parasitic resistance. The active current can be adjusted by a very small phase shift between inverter and grid voltage but the inverter voltage needs to be adjusted also. The problem is that the phase shift needed to change the current fed into the grid is extremely small 0.1-0.5 degree which is impractical and difficult to achieve. I did calculations using complex numbers with typical values of L1 = L2 = 4mH, C = 3uF and capacitor damping resistor 5 Ohm. Inductor parasitic resistance 1Ohm. Maybe I made a mistake ?
Hey , can we say that VFD's generate reactive power necessay for motors using the same concept that you explained ?
No, for vfd motor is like a load. in grid connected system, we have voltage sources in either side
Fantastic
Thank you so much...great video!!!All videos are very helpful for me.
Do you have any video on PI controller tuning?
Good work keep it up..👍
Thank you
gr8 job...Do U mind sending me the reference you have taken for this presentation like books or articles?
Can you explain what happen if angle between Vg and Vinv chenges. For my understanding this always insert reactive power component to the Ig. And the second question: what will be reaction of inverter if for example Vg will increase? Does that mean that in order to maintain PF=const at POI and Vinv-Vg=const, inverter will increase Vinv and inject additional reactiove power to the grid?
Hi Edy,
I hope you found the answers to your questions, since I now have the same confusion, and could use some explanation. I will write down my understanding and I'd appreciate it if you could correct me where I am wrong:
Q1: What happens when the angle between Vg and Vinv changes? From my understanding, this always inserts a reactive power component to the Ig.
According to the concept (beautifully explained in the video) and power flow formulas, there should only be active power generation in response to the phase difference. But when simulated, the converter produces reactive power as well. I believe the reason is that the more active current flows, the more voltage drop across the impedance, and since (Vinv = Vg + VL), it increases converter voltage which results in reactive power flow.
Q2: What will be the reaction of the inverter if, for example, Vg will increase? Does that mean that to maintain PF=const at POI and Vinv-Vg=const, the inverter will increase Vinv and inject additional reactive power to the grid?
Yes, the converter increases its output voltage to the grid level.
By adjusting voltage inverter is compensating grid requirements for reactive power. But inverter can not "push" reactive power to the grin in order to maintain grid voltage as other power sources with excitation do. Can you please explain (or simulate) voltage and frequency operational limits of the inverter? How inverter should behave in island mode of operation?
Thanks for sharing the concept . Is this concept is applicable to both voltage source and current source converter , Is this the method being used in solar inverters ?
Yes, it is the concept of three phase solar grid inverter , for Solar inverter the front part is DC to DC converter with Mppt
Which technique is followed for synchronization with grid and grid tied inverter ?
Phase locked loop. THere are many ways you can implement PLL
how to analysis the case when using svpwm technique, which generates inverter volt is not sinusoidal
3rd harmonic components will cancels each other and eventually it will be sine only
Very good explanation and thanks for uploading regular videos. I have a doubt that if we keep inverter voltage less than the grid voltage and the phase of Inverter voltage leads the phase of grid voltage. Will we see active power transfer?
Yes there will be both active and reactive power transfer.
@@TechSimulator Ah, new for me ... but how to calculate the inverter setting on pf there, or the setting for reactive power ? (My OnGrid offer both)
I think the concept will be the same as Synchronous generator , Over excite will same as increase value of Vinv , under excite will same reduce value of Vinv
Can anyone tell me the full concept of single phase pll like how the theta is calculated from vco block
But this current will be sent to the point of common coupling to mitigate harmonics required by load and full fill load reactive power requirements. Correct??
how do you send power to the grid if the voltage is smaller than the grid?
There are phasor vector
what will be the condition to import active power or reactive power?
my understanding to import active power: Vg magnitude and Vinv magnitude shall be same and Vinv shall lead Vg
Can you confirm your assumption of "sending lagging current" to the grid is - generating VAr or consuming VAr?
For generator lagging current means exporting (as you called it "generating") Vars to grid, leading current = importing Vars
Video is little fast but effective
nice
Can you make video of converter simulation using matlab function block with all type of syntex
I didint get actually, what excatly you want me to do?
@@TechSimulator in Matlab function block, you can write code like in dsp but syntexes are different. For more accurate simulation you can use trigger based system.
Mayank Amipara ok i understood. I will try to make such videos. Thanks for your suggestion
Kind of informative I enjoyed the math equations confusing as hell could have been better worded
will make it better next time
thanks！
How frequency of inverter is decided
based on many factors like, size, efficiency, type of switching device, cost etc
Can you please share the phasor diagram for 0.8 pf lag or lead case??
Ya. Sure
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