Method and system for distributing electricity over lines

A method of operating a system for distributing electricity, the system comprising:

• a first distribution line of medium voltage;
• a first secondary substation;
• and
• at least one second secondary substation, the first secondary substation having
• a first medium-voltage conductor as input conductor in the first secondary substation and connected to the first distribution line;
• a first current transformer having an output, connected to the first distribution line of medium voltage in a zone between the first secondary substation and the second secondary substation, and able to detect current along the first distribution line of medium voltage;
• a first voltage-measuring transformer having an output, connected to the first medium-voltage conductor, and able to measure voltage entering the first secondary substation;
• and
• a first phasor-measurement unit connected to the output of the first current transformer and to the output of the first voltage-measuring transformer;
• the second secondary substation having
• a second medium-voltage input conductor in the second secondary substation and connected to the first distribution line;
• a first voltage-reducing apparatus connected to the second medium-voltage input conductor;
• a second phasor-measurement unit connected to an outlet of the first voltage-reducing apparatus located in the second secondary substation;
• the system further comprising
• a receiving_processing unit suitable for receiving and processing data transmitted by the first phasor-measurement unit in the first secondary substation and data transmitted by the second phasor-measurement unit in the second secondary substation
• the method comprising the steps of:
• 1a) detecting with the first phasor-measurement unit in the first secondary substation and at certain instants of time values of current along the first distribution line detected by the first current transformer in the same first secondary substation and transmitting relative data with relative time references to the receiving-processing unit;
• 1b) detecting with the first phasor-measurement unit in the first secondary substation and at certain instants of time which are the same instants of time of a previous point voltage values at the output of the first voltage-measuring transformer in the same first secondary substation and transmitting relative data with relative time references to the receiving_processing unit;
• 1c) detecting with the second phasor-measurement unit in the second secondary substation and in certain instants of time which are the same instants of time of a previous point voltage values at an output of the first voltage-reducing apparatus in the second secondary substation and transmitting relative data with relative time references to the receiving-processing unit;
• 1d) identifying and selecting with the receiving_processing unit among data received at least a first instant in time in which a value of current relative to the first distribution line detected by the first current transformer in the first secondary substation is lower than a first predetermined threshold value;
• 1e) processing with the receiving_processing unit one or more data received from the same receiving_processing unit and regarding the first instant of time in order to perform a calibration in relation to the first voltage-reducing apparatus in the second secondary substation.