Power supply unit and related lighting system

A lighting system, comprising:

• a Power Supply Unit comprising:
• an output providing electrical power between a positive power supply line and a common ground line,
• a communication line
• an adjustable current generator responsive to an internal measurement signal generating an output current at the output,
• a voltage source coupled to the communication line,
• a current measurement unit, measuring a current through the communication line and generating the internal measurement signal depending on the measured current through the communication line,
• wherein said Power Supply Unit is configured to determine the voltage drop on said common ground line by applying two different voltages to said communication line via said voltage source;
• and
• at least one Light Engine Module,
• the Light Engine Module comprising:
• the positive power supply line,
• the common ground line,
• a plurality of LEDs connected in series between said positive power supply line and said common ground line,
• the communication line,
• a current set resistor connected between the communication line and the common ground line, with its value of conductance being indicative for the current demand of the Light Engine Module,
• a variable current generator connected to said communication line and generating a compensation current, thus modifying the current flowing through said communication line, said variable current generator being responsive to at least one measurement signal provided by at least one sensor.