1. A DC concentrated illumination system, comprising:a DC distribution box configured for converting a command specification that controls the state of the lamps into a voltage signal with a varying amplitude, and outputting the voltage signal via a power line; and
a plurality of lamp units, each of which comprises a lamp, a power conversion unit and a simulated load unit, wherein the power conversion unit is coupled to the lamp and the simulated load unit, and is coupled to the DC distribution box via the power line;
wherein the power conversion unit receives the voltage signal and determines whether the voltage signal matches a preset convention rule; if matches successfully, the power conversion unit collects state information of the lamps; and
the power conversion unit controls the action of the simulated load unit to get a current signal corresponding to the state information of the lamps, the current signal is transmitted back to the DC distribution box via the power line; and the DC distribution box parses the current signal to obtain the state information of the lamps.