What is claimed is:
1. A method for detecting a shorted turn in a synchronous machine having a rotor using a magnetic flux probe, said method comprising:
a. monitoring a signal from the flux probe during on-line operation of the machine;
b. integrating the flux probe signal to generate a flux density data trace for a rotor revolution;
c. upon detecting a variation between a current flux density trace and a prior flux density trace, capturing the flux probe signal for a current rotor revolution;
d. repeating steps (a) through(c) as the on-line operation progresses through various machine load conditions; and
e. performing a shorted turn analysis with the captured flux signal data.
2. A method as in claim 1 wherein the flux probe data is integrated in real time.
3. A method as in claim 1 wherein steps (c) and (d) are performed to capture the flux probe data while each of the individual coils in the rotor are sensitized.
4. A method for detecting a shorted turn in a synchronous machine as in claim 3 wherein an amplitude reduction for a sensitized coil in the flux probe is detected based on a variation in a timing of when the flux density trace has a predetermined value during each rotor revolution.
5. A method for detecting a shorted turn in a synchronous machine as in claim 1 wherein the variation in the flux density trace is a variation in a timing of when the flux density trace has a zero value during each rotor revolution.
6. A method for detecting a shorted turn in a synchronous machine as in claim 1 wherein the variation in flux density trace is a variation in a timing of when the flux density trace has a zero value and the variation occurs between successive rotor revolutions.
7. A method for detecting a shorted turn in a synchronous machine as in claim 1 wherein the variation in the flux density trace occurs between the flux density trace for a current rotor revolution and the flux density trace for a preceding rotor revolution.
8. A method for detecting a shorted turn as in claim 1 wherein the synchronous machine is a generator.
9. A method for detecting a shorted turn as in claim 1 wherein the rotor has a plurality of magnetic coil poles.
10. A method for detecting a shorted turn in field coils of a rotor of a generator using a magnetic flux probe, said method comprising:
a. collecting data generated by the flux probe during on-line operation of the generator;
b. integrating in real-time the flux probe signal to generate a flux density trace for successive rotor revolutions;
c. upon detecting a variation in the flux density trace for a plurality of rotor revolutions, capturing the flux probe signal of a recent rotor revolution;
d. repeating steps (a) through (c) as the generator operates at various load conditions; and
e. performing a shorted turn analysis with the flux probe signal captured in step (c).
11. A method for detecting a shorted turn in a generator as in claim 10 wherein the variation in the flux density trace is a variation in a timing of when the flux density trace has a zero value during each rotor revolution.
12. A method for detecting a shorted turn in a generator as in claim 10 wherein the variation in flux density trace is a variation in a timing of when the flux density trace has a predetermined value during each rotor revolution.
13. A method for detecting a shorted turn in a generator as in claim 10 wherein the variation in flux density trace is a variation in a timing of when the flux density trace has a zero value and the variation occurs between successive rotor revolutions.
14. A method for detecting a shorted turn in a generator as in claim 10 wherein the variation in the flux density trace occurs between the flux density trace for a current rotor revolution and the flux density trace for a preceding rotor revolution.
15. A method for detecting a shorted turn in a generator as in claim 10 wherein step (d) is performed when the machine is at various load conditions.
16. A method for detecting a shorted turn as in claim 10 wherein the rotor has a plurality of magnetic coil poles.
17. A method for detecting a shorted turn as in claim 10 wherein step (d) is performed during a period of no greater than one month.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for normal reverse playback from an Xth Group Of Pictures (GOP) of GOPs of a bitstream, the method comprising:
decoding all reference pictures in the Xth GOP;
decoding a first reference picture in a stream order in an (X\u22121)th GOP; and
sequentially designating each picture from a first picture in a reverse display order in the Xth GOP as an nth picture having a reverse display order number n and when the nth picture having the reverse display order number n is designated as a display picture, performing:
if the nth picture having the reverse display order number n is a reference picture or a B picture and an (n+1)th picture having a reverse display order number (n+1) is a B picture, decoding the (n+1)th picture having the reverse display order number (n+1) in the Xth GOP;
if the nth picture having the reverse display order number n is the B picture and the (n+1)th picture having the reverse display order number (n+1) is a reference picture, decoding a next reference picture in the stream order among undecoded reference pictures in the (X\u22121)th GOP; and
if the nth picture having the reverse display order number n is a first picture in a forward display order in the Xth GOP, decoding another first reference picture in a stream order in an (X\u22122)th GOP.
2. The method of claim 1, wherein the reference pictures comprise an I picture and a P picture.
3. The method of claim 2, wherein a structure of the GOP is IBB(PBB)m, wherein m is a natural number.
4. The method of claim 3, further comprising:
beginning the normal reverse playback from when the nth picture having the reverse display order number n meets a selected picture that is selected by a user for the normal reverse playback.
5. The method of claim 3, further comprising:
beginning the normal reverse playback from the first picture in the reverse display order of the Xth GOP to which a selected picture that is selected by a user belongs.
6. The method of claim 3, further comprising:
determining a number of pictures forming each GOP based on header information of a bitstream of the GOPs;
determining a storage capacity of a memory area for storing decoded pictures based on the number of pictures forming the each GOP; and
storing the decoded pictures in the memory area.
7. An apparatus for performing normal reverse playback from an Xth Group Of Pictures (GOP) of GOPs of a generated bitstream stored in a storage medium, the apparatus comprising:
an MPEG decoder which reads a first bitstream corresponding to an Xth GOP and an (X\u22121)th GOP from the storage medium and which decodes pictures of the Xth GOP and reference pictures of the (X\u22121)th GOP using the read first bitstream;
a frame buffer which stores the pictures decoded by the MPEG decoder; and
a display block which displays the decoded pictures stored in the frame buffer,
wherein during the normal reverse playback, the apparatus displays all the decoded pictures only once, and each display time of the decoded pictures displayed only once is the same,
wherein the MPEG decoder decodes all reference pictures in the Xth GOP; decodes a first reference picture in a stream order in the (X\u22121)th GOP; and sequentially designates each picture from a first picture in a reverse display order in the Xth GOP as an nth picture having a reverse display order number n and when the nth picture having the reverse display order number n is designated as a display picture, performs the following:
if the nth picture having the reverse display order number n is a reference picture or a B picture and an (n+1)th picture having a reverse display order number (n+1) is a B picture, decoding the (n+1)th picture having the reverse display order number (n+1) in the Xth GOP:
if the nth picture having the reverse display order number n is the B picture and the (n+1)th picture having the reverse display order number (n+1) is a reference picture, decoding a next reference picture in the stream order among undecoded reference pictures in the (X\u22121)th GOP; and
if the nth picture having the reverse display order number n is a first picture in a forward display order in the Xth GOP, decoding another first reference picture in a stream order in an (X\u22122)th GOP.
8. The apparatus of claim 7, further comprising:
a stream buffer which stores the first bitstream read from the storage medium,
wherein the MPEG decoder decodes the pictures of the Xth GOP and the reference pictures of the (X\u22121)th GOP using the first bitstream of the Xth GOP and the (X\u22121)th GOP stored in the stream buffer.
9. The apparatus of claim 7, wherein the MPEG decoder comprises:
a stream reader which reads a bitstream of two consecutive GOPs from the storage medium and which alternately outputs the two GOPs of the read bitstream;
a stream analyzer which extracts picture information by analyzing the GOPs output from the stream reader and which outputs the extracted picture information and a second bitstream;
a picture information storage unit which stores the extracted picture information; and
a decoder which generates decoded pictures by decoding the second bitstream output from the stream analyzer, based on the extracted picture information stored in the picture information storage unit.
10. The apparatus of claim 7, wherein a structure of the GOP is IBB(PBB)m, wherein m is a natural number.
11. The apparatus of claim 10, wherein the frame buffer has a storage capacity sufficient to store pictures corresponding to a total number obtained by adding a first number indicating the number of reference pictures in a GOP, a second number indicating the number of B pictures between the two adjacent reference pictures in the GOP, and 1.
12. The apparatus of claim 9, wherein the apparatus begins the normal reverse playback from when the nth picture having the reverse display order number n meets a selected picture that is selected by a user for the normal reverse playback.
13. The apparatus of claim 10, wherein the apparatus begins the normal reverse playback from a first picture in the reverse display order of the Xth GOP to which a selected picture that is selected by a user belongs.
14. The apparatus of claim 9, wherein the decoder determines a number of pictures forming each GOP based on header information of a bitstream of the GOPs;
determines a storage capacity of a memory area for storing decoded pictures based on the number of pictures forming each GOP; and stores the decoded pictures in the memory area.
15. A non-transitory computer readable recording medium storing a computer readable program for implementing functions of normal reverse playback from an Xth Group of Pictures (GOP) of GOPs of a bitstream, said functions comprising:
decoding all reference pictures in the Xth GOP;
decoding a first reference picture in a stream order in an (X\u22121)th GOP; and
sequentially designating each picture from a first picture in a reverse display order in the Xth GOP as an nth picture having a reverse display order number n and when the nth picture having the reverse display order number n is designated as a display picture, performing:
if the nth picture is a reference picture or a B picture and an (n+1)th picture having a reverse display order number (n+1) is a B picture, decoding the (n+1)th picture in the Xth GOP;
if the nth picture is the B picture and the (n+1)th picture is a reference picture, decoding a next reference picture in the stream order among undecoded reference pictures in the (X\u22121)th GOP; and
if the nth picture is a first picture in a forward display order in the Xth GOP, decoding another first reference picture in a stream order in an (X\u22122)th GOP.
16. The non-transitory computer readable recording medium according to claim 15, wherein the reference pictures comprise an I picture and a P picture.
17. The non-transitory computer readable recording medium according to claim 16, wherein a structure of the GOP is IBB(PBB)m, wherein m is a natural number.
18. The non-transitory computer readable recording medium according to claim 17, further comprising:
beginning the normal reverse playback from when the nth picture having the reverse display order number n meets a selected picture that is selected by a user for the normal reverse playback.
19. The non-transitory computer readable recording medium according to claim 17, further comprising:
beginning the normal reverse playback from the first picture in the reverse display order of the Xth GOP to which a selected picture that is selected by a user belongs.
20. The non-transitory computer readable recording medium according to claim 17, further comprising:
determining a number of pictures forming each GOP based on header information of a bitstream of the GOPs;
determining a storage capacity of a memory area for storing decoded pictures based on the number of pictures forming each GOP; and
storing the decoded pictures in the memory area.