Real-time detection of high-impedance faults
Real-time detection of high-impedance faults in a distribution circuit is described. The real-time detection of high-impedance faults includes two steps. First, adaptive soft denoising is employed to perform a filtering process on a healthy dataset, and to determine a threshold. This reduces the rate of false alarms. Second, faulty datasets are prefiltered via adaptive soft denoising, then the denoised signals are processed via discrete wavelet transform to perform high-impedance fault detection using the threshold.
1. A method for real-time detection of high-impedance faults in a distribution circuit, comprising:
obtaining an input signal from a device connected to the distribution circuit;
filtering the input signal using discrete wavelet transform via a first orthogonal wavelet to generate a denoised signal;
determining a threshold having an upper bound and a lower bound;
decomposing the denoised signal using discrete wavelet transform via a second orthogonal wavelet to generate a decomposed signal;
synthesizing a detail signal based on the decomposed signal;
comparing the detail signal to the threshold; and
based on the comparing, generating a trip or no-trip decision for a high-impedance fault detection device.
2. The method of claim 1 , further comprising:
selecting a moving window length for the input signal.
3. The method of claim 1 , wherein the input signal comprises at least one of a current signal or a voltage signal.
4. The method of claim 1 , further comprising:
placing the input signal in an instrumentation appropriate format prior to filtering the input signal.
5. The method of claim 1 , wherein the first orthogonal wavelet comprises a first Daubechies wavelet, and the second orthogonal wavelet comprises a second Daubechies wavelet that is different from the first Daubechies wavelet.
6. The method of claim 1 , wherein the threshold is based on a healthy dataset without high-impedance faults during normal operation of the distribution circuit.
7. The method of claim 1 , wherein the generating a trip or no-trip decision for a high-impedance fault detection device comprises:
generating a trip decision indicating detection of a high-impedance fault when
the detail signal is higher than the upper bound of the threshold in a first moving time window, and the detail signal is lower than the lower bound of the threshold in a second consecutive moving time window, or
the detail signal is lower than the lower bound of the threshold in a first moving time window, and the detail signal is higher than the upper bound of the threshold in the second consecutive moving time window.
8. The method of claim 1 , wherein the generating the trip or no-trip decision for the high-impedance fault detection device comprises:
generating a no-trip decision indicating no detection of a high-impedance fault when the detail signal is within the upper bound and the lower bound of the threshold.
9. A system for real-time detection of high-impedance faults in a distribution circuit, comprising:
a signal sensor configured to obtain an input signal from the distribution circuit;
a filter configured to denoise the input signal using discrete wavelet transformation via a first orthogonal wavelet to generate a denoised signal;
a threshold determiner configured to determine a threshold having an upper bound and a lower bound;
a signal analyzer configured to decompose the denoised signal using discrete wavelet transform via a second orthogonal wavelet to generate a decomposed signal;
a signal synthesizer configured to synthesize a detail signal based on the decomposed signal; and
a detector configured to compare the detail signal to the threshold and generate a trip or no-trip decision for a high-impedance fault detection device.
10. The system of claim 9 , further comprising a window length selector for selecting a moving window length for the input signal.
11. The system of claim 9 , wherein the device comprises at least one of a voltage sensor or a current sensor.
12. The system of claim 9 , further comprising a control apparatus configured to place the input signal in an instrumentation appropriate format prior to filtering the input signal.
13. The system of claim 9 , wherein the first orthogonal wavelet comprises a first Daubechies wavelet, and the second orthogonal wavelet comprises a second Daubechies wavelet that is different from the first Daubechies wavelet.
14. The system of claim 9 , wherein the threshold is based on a healthy dataset without a high-impedance fault during normal operation of the distribution circuit.
15. The system of claim 9 , wherein the detector is further configured to generate a trip decision indicating detection of a high-impedance fault when
the detail signal is higher than the upper bound of the threshold in a first moving time window, and the detail signal is lower than the lower bound of the threshold in a second consecutive moving time window, or
the detail signal is lower than the lower bound of the threshold in a first moving time window, and the detail signal is higher than the higher bound of the threshold in a second consecutive moving time window.
16. The system of claim 9 , wherein the detector is further configured to generate a no-trip decision indicating no detection of a high-impedance fault when the detail signal is within the upper bound and the lower bound of the threshold.
17. A system, comprising:
a processor; and
a memory that stores computer program logic for execution by the processor, the computer program logic including:
a filter configured to denoise an input signal using discrete wavelet transformation via a first orthogonal wavelet to generate a denoised signal;
a threshold determiner configured to determine a threshold having an upper bound and a lower bound;
a signal analyzer configured to decompose the denoised signal using discrete wavelet transform via a second orthogonal wavelet to generate a decomposed signal;
a signal synthesizer configured to synthesize a detail signal based on the decomposed signal; and
a detector configured to compare the detail signal to the threshold and generate a trip or no-trip decision for a high-impedance fault detection device.
18. The system of claim 17 , wherein the first orthogonal wavelet comprises a first Daubechies wavelet, and the second orthogonal wavelet comprises a second Daubechies wavelet that is different from the first Daubechies wavelet.
19. The system of claim 17 , wherein the detector is further configured to generate a trip decision when
the detail signal is higher than the upper bound of the threshold in a first moving time window, and the detail signal is lower than the lower bound of the threshold in a second consecutive moving time window, or
the detail signal is lower than the lower bound of the threshold in a first moving time window, and the detail signal is higher than the upper bound of the threshold in the second consecutive moving time window.
20. The system of claim 17 , wherein the detector is further configured to generate a no-trip decision when detail signal is within the upper bound and the lower bound of the threshold.