Waveform separator apparatus and method for detecting leakage current in high voltage direct current power systems
A waveform separator system for determining DC leakage current flowing through an insulating structure in a high voltage direct current power system, wherein the DC leakage current is a composite DC current comprising one or more high magnitude momentary spikes, and having a DC component and an AC component includes: (1) a waveform separator configured to receive the composite DC current flowing through the insulating structure and to separate the composite DC current into corresponding direct current (DC) and alternating current (AC) components wherein the AC component has a first rate of change, and wherein the DC component has a second rate of change, and wherein the first rate of change is greater than the second rate of change; (2) at least one comparator configured to receive the AC component and produce at least one corresponding digital signal; and (3) a processor configured to: (a) receive the at least one corresponding digital signal and the DC component, (b) analyze the at least one corresponding digital signal and the DC component, and; (c) determine a resultant leakage current flowing through the insulating structure.
1. A waveform separator system for determining DC leakage current flowing through an insulating structure in a high voltage direct current power system wherein the DC leakage current is a composite DC current comprising one or more high magnitude momentary spikes, and having a DC component and an AC component, the system comprising:
a waveform separator configured to receive the composite DC current flowing through the insulating structure and to separate the composite DC current into corresponding direct current (DC) and alternating current (AC) component wherein the AC component has a first rate of change, and wherein the DC component has a second rate of change, and wherein the first rate of change is greater than the second rate of change;
at least one comparator configured to receive the AC component and produce at least one corresponding digital signal; and
a processor configured to:
(a) receive the at least one corresponding digital signal and the DC component,
(b) analyze the at least one corresponding digital signal and the DC component, and
(c) determine a resultant leakage current flowing through the insulating structure,
further comprising at least one amplifier for amplifying the AC component and the DC component;
wherein the AC component comprises one or more positive components and one or more negative components and wherein the system further comprises at least one positive voltage comparator for counting the one or more positive components and at least one negative voltage comparator for counting the one or more negative components for producing at least one positive digital signal corresponding to the counted one or more positive components and a negative digital signal corresponding to the counted one or more negative components.
2. The system of claim 1 further comprising a current sensing circuit which, when operatively coupled to the insulating structure and the waveform separator, senses the composite DC current flowing through the insulating structure and feeds a voltage value corresponding to the sensed current to the waveform separator.
3. The system of claim 2 , wherein the current sensing circuit includes one or more shunts or shunt resistors.
4. The system of claim 1 , wherein the waveform separator comprises at least one filter circuit for separating the DC component from the AC component in the sensed DC current.
5. The system of claim 1 further comprising an averaging circuit to average the slow moving DC component over time before the DC component is fed to the at least one amplifier.
6. The system of claim 1 , wherein the DC component is substantially steady.
7. The system of claim 1 , wherein the processor is further configured to: (a) determine a correlation component from the resultant leakage current, and (b) compare the correlation component against a threshold value and to generate a comparison result signal indicative of a fault if the correlation component exceeds the threshold value.
8. The system of claim 7 further comprising a response means for receiving said comparison result signal and disseminating it through at least one dissemination interface.
9. The system of claim 7 , wherein the correlation component is a peak value or RMS value of the resultant leakage current.
10. The system of claim 7 , wherein the fault is reduced dielectric performance.
11. The system of claim 7 , wherein the fault is an impending flashover condition.
12. The system of claim 8 , wherein said dissemination at least one comprises haptic, tactile, or sensory information.
13. The system of claim 8 , wherein one or more components of the apparatus are located in a portable housing.
14. The system of claim 13 , wherein the at least one dissemination interface is associated with the housing.
15. The system of claim 14 , wherein the at least one dissemination interface is a graphical display configured to indicate at least the resultant leakage current.
16. The system of claim 13 , wherein the one or more components include the current sensing circuit, the waveform separator, the at least one comparator and the processor.
17. The system of claim 13 , wherein the one or more components include the current sensing circuit, the waveform separator and the at least one comparator.
18. The system of claim 17 , wherein the housing further includes a communicator to transfer and receive data to and from the processor.