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Hello, i am trying to simulate a simple energy system that consist of PV,battery and grid connection.
I have read several places that not all Type47 batteries and Type 48 inverters are compatible with eachother, but i cant find any documentation explaining this.
As of now i am trying to use Type47b together with Type48b, but the battery never discharge. What is the reason for that? I have also set it to NOT total charge mode, meaning that i want the PV plant to serve the load before charging.
In advance, thank you for all replies!
Hello @tobiaaas,
I am not sure why the battery doesn't discharge in your simulation. Have you looked at the example WindDieselPV.tpf (in the Examples/Stand-alone Power Systems folder of your main Trnsys18 directory)? I think it is similar to what you are trying to accomplish. The example is documented beginning on page 47 of 10-Examples.pdf, which is in the Documentation folder of your main Trnsys18 directory.
WindDieselPV.tpf uses Type48b with Type47a, but I was able to replace Type47a with Type47b (using right-click -> Replace on the proforma) and still see the battery charge and discharge over the simulation. Maybe playing around with the WindDieselPV project will help you identify why the battery is not discharging in your own simulation.
tobiaaas Topic starter
02/02/2024 9:17 am
Hello @a_weiss,
Thank you for your quick response.
I read in this 10-Examples.pdf, and it says that in the WindDieselPV.tpf example, the inverter in mode 0 is compatable with battery in mode 1 meaning that we have battery Type47a and inverter type48a (without battery), which i find a bit strange. Because when i open the example the inverter is in mode 1 and the battery is in mode 1.
So i am looking for documentation that can state what types of batteries and inverters that are compatable with eachother.
I have modified the WindDieselPV example with a Type47b battery, the inverter remains unchanged, i get it to run for some hours, but then i get the error message seen in the attached picture. Where can i modify the "time base" parameter.
As you might understand, I am new to TRNSYS.
A_Weiss 02/02/2024 4:32 pm
@tobiaaas,
I think that might be a typo in the 10-Examples.pdf that suggests inverter mode 0 pairs with battery mode 1.
I don't think there's a complete list of all combinations of batteries and inverters and which ones are compatible. In addition to the documentation, the inputs/outputs of the proformas often give clues as to which modes are compatible, for example Type48a obviously isn't designed to pair with a battery because there's no input to connect a battery's state of charge to Type48a. I would start with the simplest model of a battery and a regulator/inverter possible (Type48a and Type47a), then swap in more complicated models for the battery and/or inverter once you're comfortable with the simulation. Is there a particular reason you need to use the Shepard equation model for the battery?
I can't say from the error message alone what may have gone wrong when you replaced Type47a with Type47b in the WindDieselPV example. Did you maybe delete Type47a, drag out Type47b, and re-draw the connections? In that case there may be any number of connection errors or poor parameter/initial value changes that affected the simulation. Instead I would right-click on the Type47 proforma, select "Replace", navigate to the Studio/Proformas folder with Type47b (the folder structure is identical to the access tree in Simulation Studio), and select OK (but save the project under a new name first, just in case something goes wrong!). When I do that, the simulation runs without error. Could also be that an older version of the Types and/or the WindDieselPV example has some sort of bug. You can check your version of TRNSYS by clicking the ? -> About in the Simulation Studio. I have used both TRNSYS version 18.04.0000 and 18.05.0000 and had no issue replacing Type47a with Type 47b in WindDieselPV.
tobiaaas Topic starter
05/02/2024 9:45 am
@a_weiss Thank you, i re-drawed the connections, so i will try just replacing.
Do you have any good tips on what parameters that need a good initial value? As of now, i have just used the default values.
The reason i want to use Type 47b is that i want to simulate a flow battery ( i know that the type 47 is a lead acid, but the most important thing for me is to be able to adjust both power and energy), so with type 47b i am able to adjust the currents, thereby adjusting the battery power capacity.
Do you have any other good suggestions?
The most important parameters for Type47 are the cell energy capacity, number of cells in series and number of cells in parallel. Those three parameters will effectively set the size of the battery so that it can be charged and discharged over the time period that is appropriate to your simulation (for example fully charged by the end of the daylight hours and discharged to 20% by the time the sun comes up again.)
The second most important parameters are the ones that limit the jump in battery voltage when the battery is being charged and limit the rate at which power can be added to or removed from the battery. These are values that will be characteristic to the battery technology that you are trying to implement. For instance, a lead acid battery (and to some extent Li-ion batteries) should be limited to a jump of 2-2.5V when then are being charged. A flow battery might have different limitations.
I would also encourage you to look at the Type47 and Type48 entries in the 04-MathematicalReference.pdf document. The Type48 section talks about which modes of Type48 are designed to work with which modes of Type47.
David
