System and method of protection against inter-turn faults in excitation windings of synchronous machines with static excitation based on the comparison of the measured excitation current with the theoretical excitation current calculated for that operating point from the voltage measurements and current in the armature. (Machine-translation by Google Translate, not legally binding)
1. A system for protecting against faults between turns in excitation windings (3) of synchronous machines (1) with static excitation, characterised in that it 5 comprises: - at least one excitation current sensor (6), connected to the excitation winding (3) of the synchronous machine (1); - at least one armature current meter (4), connected to a phase of the armature winding of the synchronous machine (1); 10 - at least one armature voltage meter (5), connected to said phase of the armature winding of the synchronous machine (1); - a calculation module (14), connected to the at least one armature current meter (4) and to the said at least one armature voltage meter (5), wherein the calculation module (14) is configured to calculate a theoretical excitation current (15) as a function of at least one armature current measurement (7, 8, 9) and at least one armature voltage measurement (10, 11, 12); - a comparator module (17), connected to the at least one excitation current sensor (6) and to the calculation module (14), wherein the comparator module (17) is configured to: o make a comparison between at least one excitation current measurement (13) and the theoretical excitation current (15) multiplied by a certain coefficient (16), and; o send a trip signal (19) to a protection device, if it detects that the excitation current measurement (13) is greater than the theoretical excitation current (15) multiplied by the mentioned coefficient (16). 2. The system for protecting against faults between tums in excitation windings (3) of synchronous machines (1) with static excitation according to claim 1, characterised in that it comprises a timer (18) connected to the comparator module (17), wherein the timer (18) is configured to delay, during a predetermined time interval, sending the trip signal (19) to the protection device. 3. The system for protecting against faults between turns in excitation windings (3) of synchronous machines (1) with static excitation according to claim 1, characterised in that it comprises three armature current meters (4), each CA 03083125 2020-05-20 11 respectively connected to a phase of the armature winding of the synchronous machine (1), and three armature voltage meters (5), each respectively connected to a phase of the armature winding of the synchronous machine (1). 4. The system for protecting against faults between tums in excitation windings (3) of synchronous machines (1) with static excitation according to claim 1, characterised in that it comprises two armature current meters (4), each respectively connected to a phase of the armature winding of the synchronous machine (1), and two armature voltage meters (5), each respectively connected to the mentioned phases of the armature winding of the synchronous machine (1). 5. The system for protecting against faults between tums in excitation windings (3) of synchronous machines (1) with static excitation according to any of the preceding claims, characterised in that each armature current meter (4) comprises a current transformer. 6. The system for protecting against faults between turns in excitation windings (3) of synchronous machines (1) with static excitation according to any of the preceding claims, characterised in that each armature voltage meter (5) comprises a voltage transformer. 7. A method for protecting against faults between turns in excitation windings (3) of synchronous machines (1) with static excitation, characterised in that it comprises: - perforrning at least one excitation current measurement (13) in the excitation winding (3) of a synchronous machine (1); - performing at least one armature current measurement (7, 8, 9) in at least one phase of the armature winding of said synchronous machine (1); - performing at least one armature voltage measurement (10, 11, 12) in said phase of the armature winding of a synchronous machine (1); - calculating a theoretical excitation current (15) as a function of the at least one armature current measurement (7, 8, 9) and of the at least one armature voltage measurement (10, 11, 12); - multiplying the calculated theoretical excitation current (15) by a coefficient CA 03083125 2020-05-20 12 (16); - making a comparison between the excitation current measurement (13) and the calculated theoretical excitation current (15), multiplied by the mentioned coefficient (16); - sending a trip signal (19) to a protection device if it detects that the value of the excitation current measurement (13) is greater than the calculated theoretical excitation current (15), multiplied by the mentioned coefficient (16). 8. The method for protecting against faults between turns in excitation windings (3) of synchronous machines (1) with static excitation according to claim 7, characterised in that it comprises delaying the sending of the trip signal (19) to the protection device, during a certain time interval. 9. The method for protecting against faults between turns in excitation windings (3) of synchronous machines (1) with static excitation according to any of claims 7 or 8 characterised in that it comprises performing at least one armature current measurement (7, 8, 9) in each of the three phases of the armature winding of the synchronous machine (1), and; performing at least one armature voltage measurement (10, 11, 12) in each of the three phases of the armature winding of the synchronous machine (1). 10. The method for protecting against faults between turns in excitation windings (3) of synchronous machines (1) with static excitation according to any of claims 7 or 8, characterised in that it comprises performing at least one armature current measurement (7, 8, 9) in two of the three phases of the armature winding of the synchronous machine (1), and; performing at least one armature voltage measurement (10, 11, 12) in said two of the three phases of the armature winding of the synchronous machine (1).