Control system, transformer, protection control apparatus, and bit stream storage unit

Patent metadata

Field	Value
Publication number	US-9548606-B2
Application number	US-201213610447-A
Country	US
Kind code	B2
Filing date	Sep 11, 2012
Priority date	Mar 12, 2010
Publication date	Jan 17, 2017
Grant date	Jan 17, 2017

Abstract

According to one embodiment, the A/D conversion unit includes a ΔΣ modulating device which samples the analog electric quantity provided by the electric power system with a predetermined modulation frequency and outputs a bit stream changing over time of single bit obtained by performing ΔΣ modulation, and the digital operation processing unit includes one or more digital filters which inputs the bit stream from the ΔΣ modulating device and of which frequency characteristics differ according to a type of protection control operation, and one or more operation processing elements which perform different kinds of protection control operation processing, based on the bit stream provided by the digital filter.

First claim

What is claimed is:

1. A control system comprising:
an analog/digital conversion unit which introduces an analog electric quantity provided from an electric power system and converts the analog electric quantity into a digital quantity; and
a digital operation processing unit which performs protection control operation regarding a state of the electric power system using the digital quantity,
wherein the analog/digital conversion unit includes a ΔΣ modulating device which samples the analog electric quantity provided by the electric power system with a predetermined modulation frequency and outputs a bit stream changing over time of single bit obtained by performing ΔΣ modulation, and
the digital operation processing unit includes a plurality of digital filters each of which inputs the bit stream from the ΔΣ modulating device and of which frequency characteristics differ according to a type of protection control operation, and a plurality of operation processing elements each of which is connected to a respective digital filter and which perform different kinds of protection control operation processing regarding protection control, based on the bit stream provided by the respective digital filter.

2. The control system according to claim 1 , wherein each digital filter of the digital operation processing unit outputs data of different sampling cycles for the protection control operation processing of the protection operation processing elements, and includes processing for performing moving average in a same period as an ultimate output data cycle of the digital filter or a period longer than the ultimate output data cycle of the digital filter.

3. The control system according to claim 2 , wherein the moving average processing of the digital filter includes first stage moving average processing and decimation processing, and subsequent second stage moving average processing and decimation processing which is processing into an ultimate sampling cycle, and
the first stage moving average processing includes a combination of moving averages of two different types of tap lengths, and the first stage moving average processing includes processing for performing moving average in a same period as the ultimate sampling cycle or a period longer than the ultimate sampling cycle.

4. The control system according to claim 1 , wherein each digital filter of the digital operation processing unit has a multi-stage configuration, in which the first stage uses moving average processing and the second stage uses an FIR or IIR type digital filter, and moving average of 32 taps or more is used in the moving average processing.

5. The control system according to claim 1 , wherein in the first stage of each digital filter of the digital operation processing unit, single-bit digital filter is used, and a signal pass band of the single-bit digital filter is less than ½ of the ultimate output frequency of the digital filter, which is a Nyquist frequency, and in the second stage of the single-bit digital filter, moving average processing is used, and with moving average, data are decimated and output as digital data having multiple bits.

6. The control system according to claim 2 , wherein an output cycle of each digital filter of the digital operation processing unit is any one of electrical angles of 30 degrees, 15 degrees, 7.5 degrees, and 3.75 degrees.

7. The control system according to claim 2 , wherein at least one digital filter of the digital operation processing unit is constituted using a programmable logic device made of an FPGA or a CPLD.

8. The control system according to claim 1 , wherein the analog/digital conversion unit and some of the digital operation processing units are arranged in the same apparatus, and the other digital operation processing units are arranged outside of the apparatus, and an output unit is provided that outputs the bit streams from the ΔΣ modulating devices to the external digital operation processing units as an electrical signal or an optical signal.

9. The control system according to claim 1 , wherein the analog/digital conversion unit and the digital operation processing unit are configured as separate apparatuses, and the bit stream is transmitted via a dedicated cable from the ΔΣ modulating device of the analog/digital conversion unit to the digital operation processing unit.

10. The control system according to claim 1 , wherein the analog/digital conversion unit and the digital operation processing unit are configured as separate apparatuses, and the bit stream is transmitted via a network from the ΔΣ modulating device of the analog/digital conversion unit to the digital operation processing unit.

11. The control system according to claim 10 , wherein a data combining unit is provided that combines bit streams provided by the ΔΣ modulations of the plurality of analog/digital conversion units to make the bit streams into transmission frames in units of bytes, and then transmits the transmission frames to a network.

12. The control system according to claim 8 , wherein a gain correcting unit is provided that performs multiplying processing on the bit stream provided by the ΔΣ modulating device of the analog/digital conversion unit with multiplying processing of a gain correction value defined in advance with coefficient multiplying processing with single-bit digital processing, and outputs the bit stream, the gain of which has been corrected, to the digital operation processing unit.

13. The control system according to claim 8 , wherein a phase correction unit is provided that performs bit stream delaying processing on the bit stream provided by the ΔΣ modulating device of the analog/digital conversion unit with a phase correction value defined in advance, and outputs the bit stream, the phase of which has been corrected, to the digital operation processing unit.

14. The control system according to claim 9 , wherein the analog/digital conversion unit and the digital operation processing unit are connected via a transmission path, and the bit stream provided by the ΔΣ modulating device of the analog/digital conversion unit is distributed to the digital operation processing unit, so that electrical power transmission line protection, bus wire protection, and apparatus protection are made.

15. The control system according to claim 9 , wherein the analog/digital conversion unit and the digital operation processing unit are installed at both-end transformer substations of an electrical power transmission line, and the bit streams provided by the ΔΣ modulating devices of the analog/digital conversion units installed at the both-end transformer substations of the electrical power transmission line are transmitted via a transmission path to the digital operation processing units of the other transformer substations, and differential calculation is performed, and when a current difference is more than a predetermined value, an internal accident of the electrical power transmission line is detected.

16. The control system according to claim 9 , wherein a terminal apparatus comprises the analog/digital conversion unit and the digital operation processing unit is connected via a transmission path to a server performing protection control operation and system phenomenon analysis over a wide region of the electric power system using the bit stream provided by the ΔΣ modulating device of the analog/digital conversion unit.

17. The control system according to claim 15 , wherein the ΔΣ modulating device of the analog/digital conversion unit constitutes a feedback loop including the transmis

Assignees

• Itagaki Daiju
• Miura Shogo
• Sekiguchi Katsuhiko
• Hirano Satoshi
• Toshiba Kk
• Nat Univ Corp Nagoya Inst Of Tech

Inventors

• Itagaki Daiju
• Miura Shogo
• Sekiguchi Katsuhiko
• Hirano Satoshi

Classifications

• H03M3/462

  Details relating to the decimation process (decimation filters in general H03H17/0416, H03H17/0621) · CPC title

• H02H1/0092

  concerning the data processing means, e.g. expert systems, neural networks · CPC title

• H03M3/43

  the quantiser being a single bit one · CPC title

• H02H7/26 Primary

  Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured (locating faults in cables G01R31/08) · CPC title

• H02H3/02

  Details · CPC title