Smart Control of Power Flow

Question

Hello guys, currently I am doing a project based on Power Sharing between Solar Home Systems by Smart Control of Power Flow. Any access energy will be share a common DC grid line (neighbouring PV system interconnected each other) based on a certain logic. I need to use a microcontroller which helps to control the power flow by certain simple logic below :

For a PV system, Initially, a microcontroller is checked the panel voltage, If panel voltage is available, then the solar panel will supply the load power. Also, the battery condition is checked simultaneously. If the state of charge of the battery is less than 90%, then the battery is also charged from panel voltage, otherwise, the excess panel voltage goes to the grid for sharing. In the meantime, If there is no panel voltage like abnormal weather and night times, the battery condition is checked and if there is significant charge in the battery, then battery supplies load with necessary voltage, else the microcontroller looks for available power from the grid to borrow where other SHS also interconnected. So voltage and the current sensor also included measuring the power how much send to the grid and how much (KWH or unit) take from the grid.

So now I need help, hopefully, someone will help me how can I start to code it in Arduino ....... or how can I model it MATLAB Simulink. I am looking forward to hearing someone

best regards
Thank You
Md Abu Sayed

fmilburn · Accepted Answer

OK, that is helpful. I am glad to see from a safety viewpoint the voltage we are talking about is ~12V. This is not to dissuade you, but understand that what you are undertaking may be challenging. For example, if much current is involved and the distance is very far, the cable may need to be quite large. And there could be many other hurdles along the way. The more definition you have before starting the more likely you are to succeed. For example: What battery technology to use - e.g. Lead acid, etc. Realize that a lead acid car battery may have up to 14.5 V or so when charged. How to tell the charge level of the battery. See for example this link: https://www.energymatters.com.au/components/battery-voltage-discharge/ Decide what Arduino to use - e.g. is it 5V tolerant or 3.3V maximum. How many pins and what type will be needed. Etc. Now break the problem into pieces and develop blocks of code for that piece. Start with the block "Check panel voltage". Set up a prototype on your bench using smaller batteries. The Arduino can make analog voltage readings, but you will need to set up a voltage divider or something to get the voltage down to what the Arduino can handle. Then in the loop the Arduino function analogRead() can be used to determine the voltage. Get that working first and display the output to the serial port. Keep breaking it into pieces. Let's say that next you code a if statement and determine the panel voltage and it is >= 12 V. Then a method is needed to determine battery charge. That is why the second bullet point above needs to be answered. And so on... What mechanism is going to be used to charge the battery? Will the Arduino be controlling a relay or a separate board or what? What will be the user interface and how will information be displayed? All these questions need to be answered before coding can start. My advice is to get the best problem definition you can before going much further.

jw0752 · Answer

Hi MD,

I do not know the answer to your question but when I have been faced with similar problems in the past I have always started with a Logic Flow Chart. The next issue will be how you intend to sense the power conditions that you describe. I hope that some of the smarter guys will respond to your question so that I too can learn more. At least my response will put your question back at the top of the pile.

John

shabaz · Answer

Hi MD, That's the approach I would use too, i.e. draw a flow chart or any description that completely defines the procedure (i.e. it becomes an algorithm of some sort), in your case maybe with inputs and outputs that you wish your Arduino to sense and control. Then translate from your flow chart into pseudo-code. And then write the code from that.

fmilburn · Answer

Also, is this a project you intend to build or a school assignment? I don't know how much programming and electronics background you have but this guy goes into excruciating detail :-) on how to set up a voltage divider and read an analog pin... https://www.youtube.com/watch?v=5TitZmA66bI

fmilburn · Answer

Hi, If you can attach a flow chart with inputs and outputs, even hand drawn, as suggested above it will help. Once that is done post the parts you are having trouble coding. Do you have any code or pseudo-code written at all? It isn’t possible to help you in a meaningful way without more information.

sayed94 · Answer

Hello @Sir this my complete information about my project including algorithm and pseudocode

shabaz · Answer

Hi MD, I've not used Simulink so I cannot help there, but if you were to write it in normal Matlab code then it's not much different to writing it in any programming language. You could write it as a function or set of functions, and pass in the desired inputs and print the outputs. Your logic flow doesn't appear to use any previous historical data (i.e. you're not doing things like filtering or storing previous inputs or outputs) so a set of functions, and for your simulation test inputs (they could be in an array to run a load of tests sequentially) would be sufficient, I don't think it needs to be more complicated, based on your flow chart. In other words, the simulation becomes a set of test inputs that you design, and you record the outputs and check they meet the expectation.

fmilburn · Answer

I am glad I was helpful... I haven’t used MATLAB in quite sometime and don’t have a license for it. But I would approach a solution the same way. Start by thinking about what the physical system might look like instead of algorithms or MATLAB models. Make a drawing which shows the battery and what you know about it. Add the solar panels, charging, and instrumentation (and all pertaining information). Draw the things that will be connected to it - eg lighting, water pump, etc. Estimate the power requirements so you know how large the batteries and solar cells need to be. Show the connection to the network. Add the control system with the Arduino to the drawing after you know what it will be controlling. Then start prototyping it piece by piece as described above. The same with MATLAB- once there is a good drawing you can start to model the pieces making sure each works as it is added. The most important skill for getting help on something like this is the ability to communicate technical issues. This almost always means a drawing or sketch. Or in the case of programming a flow diagram, pseudo-code, or code snippets. If you do this others are much more likely to help.

shabaz · Answer

Hi MD, This is the area to research for your project: Test harnesses, and test suites. These are the terms that will provide you with the information on this. In brief, you'll have to design some tests, write your expected results, then run your code and view the results (for example printed to screen or file if you're simulating with Matlab or some other software) and compare with your expected results.

Smart Control of Power Flow

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I appreciate ur help @Sir