1. REACTIVE POWER SUPPLY FROM PV INVERTERS IN DISTRIBUTION NETWORKS
Mohamed Thamby Mohamed Naasir
Department of Electrical and Telecommunication Engineering,
Faculty of Engineering,
South Eastern University of Sri Lanka

2. Contents Introduction Solar PV System Self Regulations By Consumers
Reactive Power Compensation Analysis
Pros & Cons
Feasibility In Sri Lanka
References

3. Introduction
With the reduction of prices, the solar PVs getting popular
Feeding reactive power from generator plants is not effective due to increased line losses and inefficient use of generators
We have the possibility of using solar inverters as a reactive power source to system during night peaks
Also have the possibility of solving under voltage issue

4. Solar PV System

5. DC AC
Inverter convert direct current (DC) from solar PV into alternative current (AC)
We are currently using unity power factor output but, to use it for reactive power feed in we have to switch the power factor to different levels.

6. Reactive Power Feeding Methodology
By phase shifting in the inverter will change the power factor. It leads to reactive power supply capabilities
𝑄 𝑚𝑎𝑥 2 𝑡 = 𝑆 𝑚𝑎𝑥 2 − 𝑃 𝑚𝑎𝑥 2 𝑡
Reactive power supply can be capitalized by power factor variation
Apparent Power (S) Ɵ
Active Power (P)
Reactive Power (Q)
Cos Ɵ = Power Factor
Power Triangle

7. Limitations In Reactive Power Feeding
This plot explains us,
The Inverter performs relatively better in the power factor range of 0.8 to 0.85
But, can’t afford to reduce beyond 0.77 as the increasing nature of Total harmonic distortions (THD) that lowers the power quality
The variation of THD Vs power factor

8. Reactive Power Compensation
It is much important that to ensure stability of the grid reactive power demand must be compensated
During peaks we are having more reactive power requirement
Available methods of compensating reactive power
Capacitor banks
Synchronous generators
Phase advancer
Using solar PV inverters

9. Self Regulation By Consumers
Most of the reactive power demand that comes from customers like factories
It is the best solution if we able feed in reactive power from their end.
Consider following scenario,
Assume that they installed 60 kW PV system with unity power ( Case – A)
Assume that they installed 60 kW PV system with 0.95 leading power factor ( Case – B)

10. Lets compare two cases, Case A Case B
Solar system should therefore be designed to produce the maximum amount of savings across all of these areas.
For example, it maybe financially beneficial to reduce the amount of active power drawn from the grid at the expense of increased charges due to a poor power factor.

11. Reactive Power Feed In Methods Of Inverters
Fixed Power Factor Operation
Multi Level Inverter With SCADA Control Capability
Time Based Control

12. Voltage Regulation
The inductive coupling in the transmission network and resistive coupling in distribution network leads to different scenarios of voltage control
The enhancement of voltage regulation by using a power factor control method
Power factor control of PV inverters

13. Low Voltage Feeders
During late evening peaks more reactive power need & under-voltage issue rises while panels produce no energy.
PV inverters can be used to feed reactive power to system like a STATCOM.
Hence, reactive power to the grid can be obtained from solar inverters.
By using customers’ inverter, utility’s Low Voltage (LV) system also can be improved.

14. Operation Of Inverter During Night
Inverter will be connected series to the grid.
It will feed pure reactive power.
Inverter takes active power to charge capacitors
Inverter supplies reactive power to grid

15. Improving Line Efficiency
𝐼= 𝑃 2 + 𝑄 2 𝑉 ; line current (I), phase voltage (V)
injecting reactive power at the load side increases the voltage and reduces the line current. The line losses reduce with the reduction in line current.
maximum transfer capability ,
𝑃 𝑚𝑎𝑥 = 𝑉 2 (−𝑘+ 1+ 𝑘 2 ) 2𝑋 ; 𝑘= 𝑃 𝑄 & reactance of the system (X)
Economic benifit,
already available in the grid that doesn’t want an additional investment regardless of compensation for consumers

16. Cost Factors for Reactive Power from Solar Inverters
Inverter losses can be assumed independent from the power factor and PAC can be substituted by S with only small errors.
𝑃 𝑙𝑜𝑠𝑠 𝑠 = 𝑐 𝑠𝑒𝑙𝑓 + 𝑐 𝑉𝑙𝑜𝑠𝑠 ⋅ 𝑆 + 𝑐 𝑅𝑙𝑜𝑠𝑠 ⋅ 𝑆 2
The losses are categorized into two
During the daytime - reduce this active power injection
During the night - inverter losses due to the reactive power supply
Oversizing of the inverter is needed
Inverter lifetime assessment for injecting reactive power

17. ADVANTAGES & DISADVANTAGES
Poor reliability
Additional thermal stress will be on inverters
Additional cost
Consumers needed to be well educated of system otherwise they don’t get attract
Life time of inverter will reduce
Reduced Line Losses
Can eliminate the cost of generators to feed reactive power and capacitor banks
More economical benefits since consumer getting paid for reactive power
Increased Line Capacity
Consumer no need to rely on grid
Total Harmonic Distortion (THD) will be decreased
Micro grids can accommodate

18. Normal operation Power factor Available additional PF option
Feasibility in Sri Lanka
The following table contains commonly used inverters in Sri Lanka
Inverter Brand
Normal operation Power factor
Available additional PF option
SMA Sunny boy 1.5, 2.5
Unity
0.8 ( lead/ lag)
Growatt 7000UE, 8000UE, 9000UE
GoodWE 1000-NS, 1500-NS, 2000-NS, 2500-NS, 3000-NS
0.9 ( lead/ lag)
KACO blue planet 15.0 TL3, 20.0 TL3
0.7 (lead/lag)
Omniksol-m248 micro inverter
Not supported
Solis
JYINS
AP Systems YC 500A micro inverters
Solar EDGE
ABB
0.8 (lead/ lag)
It clearly shows that we have difficulties to implement in operating different power factor to solve under voltage issue as some widely us.So It is needed that we need to introduce standards for inverters that includes reactive power producing capability which exists in several countries

19. Conclusions
"As a customer premises equipment, solar inverters can be utilized for empowering the grid"
relevant compensation should provide to consumers by considering the benefits and costs
we can operate inverter within power factor range as further reduction increases the THD
It is preferable to operate in 0.85 power factor where results in superior
Existing tariff methodology must be revised in terms of reactive power usage. As tariff only contains maximum demand charge to account reactive power usage which is inadequate
we must properly address economic benefits for consumers to use their inverters by considering aforementioned cost and benefits
This scheme would increase the overall economic efficiency of solar inverters.

20. References
Gandhi, O., Rodriguez-Gallegos, C. D., Gorla, N. B. Y., Bieri, M., Reindl, T., & Srinivasan, D. (2019). Reactive Power Cost from PV Inverters Considering Inverter Lifetime Assessment. IEEE Transactions on Sustainable Energy, 10(2), 738–747.
Navoda, K. K., & Rodrigo, A. S. (2017). Optimum Use of Solar Inverter by Feeding Reactive Power at the Night. Annual Sessions of IESL
Santos-Martin, D., Lemon, S., Watson, J. D., Wood, A. R., Miller, A. J. V., & Watson, N. R. (2016). Impact of solar photovoltaics on the low-voltage distribution network in New Zealand. IET Generation, Transmission & Distribution, 10(1), 1–9.
Beach, T., Kozinda, A., & Rao, V. (2013). Latent Opportunities for Localized Reactive Power Compensation, “Cal x Clean and coalition Energy C226”
Kutkut, N., & Solar, P. (2012). An AC PV Module with Reactive Power Capability: Need and Benefit.
Braun, M. (2008). Reactive power supply by distributed generators IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century,
Braun, M. (2007). 22nd European Photovoltaic Solar Energy Conference and Exhibition, September 2007, Milan, Italy.
Soorya Bala Sangramaya (Battle for Solar Energy) (2019, July 30). Retrieved from //energy.gov.lk/index.php/en/soorya-bala- sangramaya

21. Thank You
After you’ve done your research, it’s time to put your presentation together. The first step in the process is to introduce the topic. This is a great time to connect your topic to something that your audience can relate. In other words, why should they listen to all the information you will be sharing in your research presentation? What is in it for them? You may also want to include a graphic or image to grab their attention.
Feel free to duplicate this slide by right-clicking on this slide in the slides pane to the left and select Duplicate Slide.
The next step in your presentation is to state your claim or topic clearly. Your teacher may even call this your thesis. As you state your thesis, you may find that this layout is not the best layout for your claim or topic. You can change the layout by clicking the drop-down menu next to the Layout in the Slides menu section. You can choose Two Content, Comparison, or Picture with Caption. Note: A different layout might change the look of the icons on this page.
You will also want to state your facts. You have done the research now share some of the interesting facts with your audience. Facts do not have to be boring; you can communicate facts in a variety of ways by going to the Insert Tab. In the Insert tab you can:
Insert pictures from your computer or online.
Add a chart
Create some SmartArt
Insert a variety of icons to help your facts come to life. Note: You can change the color of the icons by selecting the icon and then click on the Format tab and then Graphics Fill. From there, you will choose a color from the list or choose More Fill Colors to give you more options.
Since this research presentation is a result of your hard work and searching, you want to make sure you support the claims or points in your presentation with facts from your research findings. Make sure you give the author proper credit for helping you share your ideas. If one of your sources has a video that is relevant to your topic, you can add the video as added support. Keep in mind the length of the video and the amount of time you have for your presentation. For a 5 minute speech, the video should be no longer than 30 seconds.
Questions to consider:
How will you state the author of the source?
Will you need to cite the source on the slide?
What are some ways you can engage your audience so they feel like they are a part of the presentation? Some ideas to consider is by taking a quick poll like: by a show of hands, how many of you think school uniforms are a way to cut down on bullying? Another suggestion is to have them hold up a certain number of fingers to see if they agree or disagree. Finally, you can share a story that the audience can relate to that makes them laugh.
After all the applause, your audience may have some questions. Be prepared to answer some of their questions by making a list of questions you think they might ask. You may also want to share the presentation with them by providing the link to your presentation, if they want more information.
Questions ?

22. Research Presentation End
You can use this slide as your opening or closing slide. Should you choose to use it as a closing, make sure you review the main points of your presentation. One creative way to do that is by adding animations to the various graphics on a slide. This slide has 4 different graphics, and, when you view the slideshow, you will see that you can click to reveal the next graphic. Similarly, as you review the main topics in your presentation, you may want each point to show up when you are addressing that topic.
Add animation to images and graphics:
Select your image or graphic.
Click on the Animations tab.
Choose from the options. The animation for this slide is “Split”. The drop-down menu in the Animation section gives even more animations you can use.
If you have multiple graphics or images, you will see a number appear next to it that notes the order of the animations.
Note: You will want to choose the animations carefully. You do not want to make your audience dizzy from your presentation.
Research Presentation End