Secured fault detection in a power substation
Systems and methods for fault detection and protection in electric power systems that evaluates electromagnetic transients caused by faults. A fault can be detected using sampled data from a first monitored point in the power system. Detection of fault transients and associated characteristics, including transient direction, can also be extracted through evaluation of sample data from other monitored points in the power system. A monitoring device can evaluate whether to trip a switching device in response to the detection of the fault and based on confirmation of an indication of detection of fault transients at the other monitored points of the power system. The determination of whether to trip or activate the switching device can also be based on other factors, including the timing of receipt of an indication of the detection of the fault transients and/or an evaluation of the characteristics of the detected transients.
1. A method comprising:
detecting, by a first monitoring device, a fault in a power system,;
detecting, by one or more other monitoring devices, one or more fault transients;
receiving, by the first monitoring device, an indication of the detection, by the one or more other monitoring devices, of the one or more fault transients
determining to trip a switching device of a power system in response to the detected fault and the detected one or more fault transients, wherein the step of determining to trip the switching device includes determining whether the first monitoring device received an indication of the detection of the one or more fault transients within a predetermined time period;
determining, by the first monitoring device and using first sampled data of a first monitoring point of the power system, a first fault direction of a first fault transient; and
determining, by the one or more other monitoring devices and using sampled data of at least a second monitoring point of the power system, a second fault direction of at least one of the one or more fault transients,
wherein the step of determining to trip the switching device includes determining whether the first fault direction is consistent with the second fault direction,
wherein determining the first fault direction comprises:
calculating an instantaneous energy direction for the first fault transient by obtaining a decoupled mode voltage and a decoupled mode current for each of several tracked fault component voltages and currents;
calculating instantaneous active power and instantaneous reactive power for each of the decoupled mode voltages and decoupled mode currents;
accumulating the instantaneous active powers and instantaneous reactive powers to form instantaneous active energies and reactive energies; and
evaluating the signs of the instantaneous active energies and reactive energies to determine the fault direction for the electromagnetic transient.
2. A method comprising: detecting, by a first monitoring device, a fault in a power system, detecting the fault comprises detecting a presence of the fault using phasor calculations; detecting one or more fault transients, the one or more fault transients being generated by electromagnetic fault transients propagating in a substation of the power system; confirming, by the first monitoring device, based on detection of the fault and the detection of the one or more fault generated electromagnetic fault transients in the substation, the presence of the fault in the power system; and determining, by the first monitoring device, to trip a switching device of a power system in response to the confirmed presence of the detected fault; and wherein the first sampled data comprises at least one of a first sampled current data and a first sampled voltage data, and wherein the step of detecting one or more fault transients comprises detecting, by a second monitoring device, one or more fault transients using second sampled data, the second sampled data comprising at least one of a second sampled current data and a second sampled voltage data.
3. The method of claim 2 , wherein the step of detecting the one or more fault transients comprises:
high-pass filtering the second sampled data; and
determining whether the filtered second sampled data exceeds a pre-determined amplitude.
4. The method of claim 2 , wherein the step of detecting the one or more fault transients is performed by one or more other monitoring devices.
5. The method of claim 4 , further including the step of receiving, by the first monitoring device, an indication of the detection, by the one or more other monitoring devices, of the one or more fault transients.
6. The method of claim 5 , wherein the step of determining to trip the switching device includes determining whether the first monitoring device received an indication of the detection of the one or more fault transients within a predetermined time period.
7. The method of claim 6 , further including the steps of:
determining, by the first monitoring device and using first sampled data of a first monitoring point of the power system, a first fault direction of a first fault transient; and
determining, by the one or more other monitoring devices and using sampled data of at least a second monitoring point of the power system, a second fault direction of at least one of the one or more fault transients,
wherein the step of determining to trip the switching device includes determining whether the first fault direction is consistent with the second fault direction.
8. The method of claim 7 , wherein determining the first fault direction comprises:
calculating an instantaneous energy direction for the first fault transient by obtaining a decoupled mode voltage and a decoupled mode current for each of several tracked fault component voltages and currents;
calculating instantaneous active power and instantaneous reactive power for each of the decoupled mode voltages and decoupled mode currents;
accumulating the instantaneous active powers and instantaneous reactive powers to form instantaneous active energies and reactive energies; and
evaluating the signs of the instantaneous active energies and reactive energies to determine the fault direction for the electromagnetic transient.
9. The method of claim 2 , wherein the step of detecting the fault includes receiving, by a first monitoring device, first sampled data for a first monitored point in the power system and detecting the fault using the first sampled data, and wherein the step of detecting the one or more fault transients includes receiving second sampled data for a second monitored point and determining that the second sampled data indicates a fault transient at the second monitored point.
10. The method of claim 9 , further including the steps:
determining a first direction for a first fault transient at the first monitored point; and
determining a second direction for the fault transient at the second monitored point,
wherein the step of determining to trip the switching device includes determining whether the first fault direction is consistent with the second fault direction.