Hi
to control my feedin to the battery, I have a code tweaking the Setpoint made by help from some guys from Germany a while ago.
Due to sometimes we need to pay for delivering to the net at full battery, I have tried to make a code that reset this tweak simply by setting the setpoint to 0 if the price is too low.
Id to though not always work and the input to the code from Nordpool gives the corrct input for the code to work.
Any inputs why it seems not always to work?
Thank you very much :-)
Do you mind sharing how you're defining the variables? Is there a chance that sometimes one of the var's is undefined when the code is running. Which is causing the inconsistent outcome.
Yes it can be the case and I'm not that good in Node Red, so might be doe wrong. I keep it very basic and do not keep it that compact, so I have a chance of editing it later.
Hi @larsea-dk
Here's my guess. So your setup is you have multiple data nodes populating msg and you use change nodes to assign them a key?
That should work fine however what happens if the data node for BAT isnt populated at the same time as Shunt v for example.
If Shunt V node sends data, this then flows into the function, however BAT node hasn't send data yet but the function is running as soon as it receives a message from SHunt V? So BAT is undefined and SHunt V isn't. This is my guess for why you're code is running inconsistently, sometimes the variables are undefined.
The fix I'd use is something like this but for all variables:
Essentially if variable is undefined you have to get the contents from somewhere. ie the last value that's available so i store in global context.
and write to global context when updating it.
var soc = global.get('soc');
var acSolar = global.get('acSolar');
//setting soc variable depending on inputs from flows
if (msg.payload['soc'] !== undefined) {
soc = msg.payload['soc']; // Extract payload from input 1
global.set('soc', soc);
}
if (msg.payload['acSolar'] !== undefined) {
acSolar = msg.payload['acSolar']; // Extract payload from input 2
global.set('acSolar', acSolar);
}
However if you're using newer version of venus of you dont need to use msg at all as victron node data is stored in global context. More on that approach here:
Node-RED - update for Victron users - Victron Energy
I also think the value might be lost...I have a Debug running and here the value for infeed activated or not activated to not always show. So I think you have a point!
In addition to my comment I thought it might be useful to share some code i wrote for someone awhile back doing something similar but using time criteria as well as ac and dc solar: My guess is the reading last available value from global is the bit that's causing your issues as this prevents vars being undefined.
As noted in comment you can read victron data directly from global context in more recently versions of venus os (I've put link for more details on that in the comment reply above)
//setting up time variables
var currentTime = new Date();
var hours = currentTime.getHours();
var minutes = currentTime.getMinutes();
//setting up data variables. If using up to date venus os you could get these directly via global context.
var soc = global.get('soc');
var acSolar = global.get('acSolar');
var dcSolar = global.get('dcSolar');
var gridSetpoint = global.get('gridSetpoint');
//setting soc variable depending on inputs from flows
if (msg.topic === "soc") {
soc = msg.payload; // Extract payload from input 1
global.set('soc', soc);
}
if (msg.topic === "acSolar") {
acSolar = msg.payload; // Extract payload from input 2
global.set('acSolar', acSolar);
}
if (msg.topic === "dcSolar") {
dcSolar = msg.payload; // Extract payload from input 3
global.set('dcSolar', dcSolar);
}
//this is used to check if gridsetpoint is already 0, if it is then we won't bother updating it.
if (msg.topic === "gridSetpoint") {
gridSetpoint = msg.payload;
global.set('gridSetpoint', gridSetpoint);
}
if (msg.topic === "acLoad") {
acLoad = msg.payload; // Extract payload from input 2
global.set('acLoad ', acLoad);
}
//two examples of times
if (hours >= 10 && hours < 14) { //if time is between 10am-1.59pm
if (soc > 70 && acLoads < 10000) { //if state of charge is above 70%
//return the new grid setpoint
gridSetpoint = -Math.min(acSolar + dcSolar, 6000);
} else {
gridSetpoint = 0;
}
} else if (hours >= 14 && hours < 19) { //if time is between 2pm and 6.59pm
if (soc > 50 && acLoads < 10000) { //if state of charge is above 50%
//return the new grid setpoint
gridSetpoint = -Math.min(acSolar + dcSolar, 6000);
} else {
gridSetpoint = 0;
}
} else if (hours >= 19 && hours < 23) { //if time is between 7pm and 10.59pm
if (soc > 30 && acLoads < 10000) { //if state of charge is above 30%
//return the new grid setpoint
gridSetpoint = -Math.min(acSolar + dcSolar, 6000);
} else {
gridSetpoint = 0;
}
} else {
gridSetpoint = 0;
}
if (gridSetpoint !== global.get('gridSetpoint')) { // Check if gridSetpoint is going to change
global.set('gridSetpoint', Math.min(gridSetpoint, 0));
msg.payload = Math.min(gridSetpoint, 0);
return msg;
}
I did some check at the msg controlling if feedin is active or deactivated. This is controlled by an input from a hourly check of the market price. So this msg is only populated once per hour and rest seems to be populated almost at the same time. …they do at least all show on the debug list. The feedin msg do though miss even though the value has been populated once.
Is this the fault perhaps.
I am thinking of having this check somewhere else than in this function, but what could be an idea. Before the function tweaking the grid Setpoint maybe, cause if price is low, the grid Setpoint do not need to be tweaked actually.
Hi @larsea-dk
Just so I'm understanding correctly. You're saying all your variables update frequently except for price which updates hourly and you're then having issues where all the frequent variables have updated but the price is becoming undefined?
If that's the issue/if I've understood correctly you could adjust your flow to write the price to global context. ie
//in the node where you get price;
global.set("price",msg.payload);
Then in your gridsetpoint function you access it
var price = global.get("price");
And used something like
if(price > x){
//orignal code you have
}else if(gridsetpoint !== 0) { //stops you spamming new gridsetpoint messages if it's already 0;
//set gridsetpoint = 0;
}
However like you said you could do this externally to the function so the function doesnt even run if it's not at the right price.
I'm happy to help with more code if you know exactly what you're looking for.
