Method and System for Time Synchronization of Sensor Units

A method for time synchronization of sensor units in a distributed system, the sensor units each respectively having an internal time unit, and sensor data being captured by the sensor units and transmitted to a central unit via a radio network, and an identification signal being transmitted in the radio network at regular time intervals, the method comprising:

• monitoring reception of the identification signal in a respective sensor unit;
• storing a current value of the internal time unit of each respective sensor unit with at least one transmitter identification contained in the identification signal upon receipt of a characteristic time feature of the identification signal;
• storing a further current value of the internal time unit of the respective sensor unit upon capture of sensor data;
• assigning the captured sensor data at least a value of the internal time unit stored upon receipt of the characteristic time feature of the identification signal, the associated transmitter identification of the identification signal and the further value of the internal time unit stored upon capture of the sensor data and transmitted together with the sensor data to the central unit;
• deriving a reference time base based on the transmitter identification and a temporal relationship of the transmitted sensor data of the respective sensor unit to the reference time base based on the value of the internal time unit of the respective sensor unit stored upon receipt of the characteristic time feature of the identification signal and the further value of the internal time unit of the respective sensor unit stored upon capture of the sensor data;
• capturing, by the central unit, voltage and phase values of at least one of three phase conductors of a power supply network from which synchronization data for a frequency or period and a phase angle of the voltage of at least one of the three phase conductors in relation to time of capture of the voltage and phase values of the at least one of the three phase conductors is ascertained and transmitted to the sensor units;
• and
• capturing, by the respective sensor unit, the respective sensor data as current values in relation to synchronization data, the sensor data being transmitted to the central unit and, in the central unit, powers being calculated from the voltage values and current values.