# there is no monitor attached

$ xrandr -q -d :0
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 4096 x 4096
VGA-1 disconnected primary (normal left inverted right x axis y axis)
LVDS-1 disconnected (normal left inverted right x axis y axis)
DVI-D-1 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)

# Write in xorg.conf

$ cat /etc/X11/xorg.conf
Section "Device"
        Identifier      "Configured Video Device"
EndSection

Section "Monitor"
        Identifier      "Configured Monitor"
EndSection

Section "Screen"
        Identifier      "Default Screen"
        Monitor         "Configured Monitor"
        Device          "Configured Video Device"
        SubSection "Display"
                Virtual 1920 1080
        EndSubSection
EndSection

# for disabling the LVDS-1 Port because it show as connected even if it's now
robo@demopc16:~$ cat /etc/default/grub
...
GRUB_CMDLINE_LINUX_DEFAULT="{} video=LVDS-1:d"