Good Morning
I would like to implement the control of three inverters [MultiPlus-II 48/5000/70-50] via Modbus TCP in a way that allows them to give or take power from the grid (grid). The process would consist of entering the appropriate value into a register, based on which the inverter would automatically determine whether it should give or take power from the grid, the amount of this power would also be controlled by sending the value to the register. Mainly, we want to achieve the mode of operation that is given in example 6.2 on the page: https://www.victronenergy.com/live/ess:ess_mode_2_and_3
The example was rewritten from the page given above:
These instructions tell the Multi to charge at 32kw.
Set Register 38 to 0
Set Register 39 to 1
Set Register 37 to 32700
Devices that are used in the control process:
3 MultiPlus-II inverters
GX Device
PLC (Connects to the GX Device and sends commands to it)
Energy Meter (An additional device that checks whether the inverters are giving out/collecting energy correctly)
Things I have tested at this point:
The examples given below were tested on 2 assistants. The first was an ESS assistant the second was Hub4. The data sent to the registers for ESS was every 10.5s and for hub4 every 5.5s.
The mode of both assistants was set to external control. The batteries were charged to 70% where the critical values set in the assistants for the batteries were at 50%.
I have correct communication between inverters-GX Device and GX Device-plc
GX Device is able to correctly receive registers received from the PLC but does not execute them correctly, e.g.
Sending a register
38 = 1 Makes the inverter go into passthru mode (Works correctly)
39 = 1 and 38 = 0 Makes the inverter go into charge mode (Works Properly)
39 = 1, 38 = 0 and 37 = 300 Makes the inverter start drawing 270-330W from the Grid (Deems it to be working properly)
39 = 0, 38 = 0 and 37 = -100 Makes the battery neither charge nor discharge (0W)
39 = 0, 38 = 0 and 40,41 Setting to any positive/negative number changes nothing in the circuit (Inverters do not respond to received data)
Additional Registers that have been checked:
71 = 0 (AcPowerSetpoint acts as feed-in limit), 2902 = 3 (ESS Mode)
From additional information I can say that the device was also checked on two additional modes added by the manufacturer [Keep batteries charge and Optimized (without BatteryLife)] and the values from the registers above were read. The registers had the values:
During Battery charge: Registers 37,40,41 were positive, e.g. 37=200, 40=200,41=200.
While discharging the Battery: One of the Registers was negative and the rest were slightly positive, e.g. 37=50, 40= -1000, 41 = 50. Then after about 15s the phase changed, i.e. 37=50, 40=50, 41=-1000.