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Thread: ABB with Selectronic Off Grid Solution

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    Default ABB with Selectronic Off Grid Solution

    I am putting this out there as information for others wishing to have a similar solution.

    As a background :-
    When a Hybrid system loses the grid, the PV inverter power has to be absorbed by something.

    This usually is done utilizing some form of load to dissipate the excess energy, with some form of control also used to supply the house load as it varies.
    The problem with this is that the energy is lost as heat when not used, even dumping into a hot water system, eventually the energy is lost when the water is hot enough.

    Selectronics when coupling to ABB inverters uses their own system (Selectronic Certified) inverters, that provide managed AC coupling, what this does, is to reduce the PV generation when the energy is in excess of the requirements.

    When using Generic AC coupling, the Selectronics causes the inverters to turn off utilizing frequency ramping.
    This stops the excess energy overcharging the batteries, the problem with this is that the inverter will restart after one minute and the cycle repeats. Not very good for the inverter.

    So its a good idea to purchase the managed AC coupling inverters from Selectronics from the start, it overcomes the above problem.

    However if like me you already have the non approved inverters and added a Selectronic battery system you will have to put up with the things going on and off every minute when the grid is off, or spend more money replacing the perfectly good inverter.

    I designed a management controller to do the same that Selectronic does, utilizing an ABB supplied component that controls the power output of the inverter, called a PVI PMU

    This device is digitally controlled and can vary the PV power from 100% down to 0% in 11 steps, it uses the RS485 bus to communicate with the inverter.

    The system I have developed, monitors battery voltage, further this voltage is temperature compensated to track the Selectronic charger that increases or decreases the charge voltage due to battery temperature variation.

    Under normal conditions the battery voltage is maintained at the charge cycle as determined by the Selectronic charger.

    The device monitor if the maximum voltage for the battery is exceeded, this than causes the PMU to start its control of the power output of the inverter reducing power to the allowed float voltage.

    A balance is achieved when the PV will only be producing enough power for the house load and what ever the battery is requiring.
    Should the house load increase, the battery voltage will drop below the Float Voltage, this is overcome by the PMU raising the PV output back to the float voltage balance point...

    This float voltage has a capture window (User settable +/- voltage), this is how the fine control is achieved.


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    tristen (30-04-17)



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    Quote Originally Posted by Percul View Post
    I am putting this out there as information for others wishing to have a similar solution.

    As a background :-
    When a Hybrid system loses the grid, the PV inverter power has to be absorbed by something.

    This usually is done utilizing some form of load to dissipate the excess energy, with some form of control also used to supply the house load as it varies.
    The problem with this is that the energy is lost as heat when not used, even dumping into a hot water system, eventually the energy is lost when the water is hot enough.

    Selectronics when coupling to ABB inverters uses their own system (Selectronic Certified) inverters, that provide managed AC coupling, what this does, is to reduce the PV generation when the energy is in excess of the requirements.

    When using Generic AC coupling, the Selectronics causes the inverters to turn off utilizing frequency ramping.
    This stops the excess energy overcharging the batteries, the problem with this is that the inverter will restart after one minute and the cycle repeats. Not very good for the inverter.

    So its a good idea to purchase the managed AC coupling inverters from Selectronics from the start, it overcomes the above problem.

    However if like me you already have the non approved inverters and added a Selectronic battery system you will have to put up with the things going on and off every minute when the grid is off, or spend more money replacing the perfectly good inverter.

    I designed a management controller to do the same that Selectronic does, utilizing an ABB supplied component that controls the power output of the inverter, called a PVI PMU

    This device is digitally controlled and can vary the PV power from 100% down to 0% in 11 steps, it uses the RS485 bus to communicate with the inverter.

    The system I have developed, monitors battery voltage, further this voltage is temperature compensated to track the Selectronic charger that increases or decreases the charge voltage due to battery temperature variation.

    Under normal conditions the battery voltage is maintained at the charge cycle as determined by the Selectronic charger.

    The device monitor if the maximum voltage for the battery is exceeded, this than causes the PMU to start its control of the power output of the inverter reducing power to the allowed float voltage.

    A balance is achieved when the PV will only be producing enough power for the house load and what ever the battery is requiring.
    Should the house load increase, the battery voltage will drop below the Float Voltage, this is overcome by the PMU raising the PV output back to the float voltage balance point...

    This float voltage has a capture window (User settable +/- voltage), this is how the fine control is achieved.

    The prototype is completed

    Operating Specifications :-
    Operational Voltage Range Intended 40 to 60 Volts ( Tested 15 to 60 V)
    Current consumption 160mA
    Processor ATMega 328
    Program Size Including Variables 4.2K
    Voltage sensing 0 to 100 V
    Temperature sensing -30 to 100 C

    Operational
    Power Failure sensing.
    Battery Over Voltage Sensing.
    Fine control of PV inverters.
    Sensing is temperature compensated.

    To be used in conjunction with ABB PVI controller
    24 Volt Output Regulated for ABB PMU
    0 to 20mA constant current source for ABB PMU power factor control
    11 step digital 4 bit output 0 to 100% control.
    PL (%) K1 K2 K3 K4 (Power One Proprietary Code)
    100, 90, 80, 70, 60, 50, 40, 30, 20, 15, 0




  • The Following User Says Thank You to Percul For This Useful Post:

    tristen (30-04-17)

  • #3
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    Quote Originally Posted by Percul View Post
    The prototype is completed

    Operating Specifications :-
    Operational Voltage Range Intended 40 to 60 Volts ( Tested 15 to 60 V)
    Current consumption 160mA
    Processor ATMega 328
    Program Size Including Variables 4.2K
    Voltage sensing 0 to 100 V
    Temperature sensing -30 to 100 C

    Operational
    Power Failure sensing.
    Battery Over Voltage Sensing.
    Fine control of PV inverters.
    Sensing is temperature compensated.

    To be used in conjunction with ABB PVI controller
    24 Volt Output Regulated for ABB PMU
    0 to 20mA constant current source for ABB PMU power factor control
    11 step digital 4 bit output 0 to 100% control.
    PL (%) K1 K2 K3 K4 (Power One Proprietary Code)
    100, 90, 80, 70, 60, 50, 40, 30, 20, 15, 0



    Final version of both Hardware and Software now completed with the addition of a fan within the controller box to keep things cool when internal temperature raises above 26 C

    Software rewrite to make code execution faster

    Videos show the operational cycle from AC Fail to Over volt, Float and Under volt where the PMU is reacting to the changes .

    All is left to do is to heat soak test, followed with installation in the real world.

    Other video shows the FAN operation..

    Sorry for the video shake ... hard to video and operate the power supply..

    Shows operational simulation


    Shows Fan indication


    The CPU Program Code (Architecture Arduino Nano ATmega328)
    Language C ++ Using Arduino Libraries
    Communication USB to RS232
    Internal Temperature management.
    Input Signals-
    Battery Voltage [Also used to power Controller Range 60V to 40V (Actual 15 V to 60 V)]
    Grid Fail Acquired from Selectronic Logic
    Battery Temperature (20K Thermistor)

    Output -
    4 bit digital K1, ... K4
    24 V DC Regulated to PVI PMU
    Constant current output 0 to 12 mA adj. Set power factor on PVI PMU

    Copy of Code Released with GNU permissions

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