Reception of digitally coded protection signals in a remote tripping device

• US 20030151871A1
• Filed: 02/06/2003
• Published: 08/14/2003
• Est. Priority Date: 02/12/2002
• Status: Abandoned Application

• Current Assignee: ABB Power Grids Switzerland AG (ABB Limited)
• Original Assignee: ABB Schweiz AG (ABB Limited)
• Inventors: Schnyder, Hermann
• Application Number:
  US10/359,090
• Publication Number:
  US 20030151871A1
• Time in Patent Office: Days
• US Class Current: 361/91.1
• CPC Class Codes: H02H 1/0061 concerning transmission of signals transmission of measured quantities or switching orders; sectionalised protection involving signal transmission between at least two stations H02H7/261; comparison of the voltage or current values at two spaced portions of a single system H02H3/28; transferring the output of a sensing member to another variable G01D5/00; electrical measuring arrangements using modulation of electromagnetic waves, e.g. light beams G01R15/24, G01R15/26
• CPC Class Codes: H02H 7/261 involving signal transmission between at least two stations transmission of signals in general H02H1/0061

Abstract

In a remote tripping device and in a method for reception of digitally coded protection signals in a remote tripping device, a sequence of digital code words is received on a transmission channel, and a protection signal is regarded as having been received when a code which corresponds to this protection signal has been detected in this sequence a total of n times within a time window of predetermined length, wherein the number n is determined on the basis of an estimate of a measure at any given time of a disturbance on the transmission channel.

Claims

1. A method for reception of digitally coded protection signals in a remote tripping device for distance protection in electrical systems, in which a sequence of digital code words is received on a transmission channel, and a protection signal is regarded as having been received when a code which corresponds to this protection signal has been detected in this sequence a total of n times within a time window of predetermined length, characterized

in that the number n is determined on the basis of an estimate of a measure at any given time of a disturbance on the transmission channel.

2. The method as claimed in claim 1, characterized in that the measure of the disturbance on the transmission channel is a bit error rate on the transmission channel, and the number n is determined on the basis of the bit error rate and a requirement for the safety and/or security level of the transmission.

3. The method as claimed in claim 2, characterized in that the bit error rate is determined on the basis of the received sequence of code words.

4. The method as claimed in claim 1, characterized in that a number of protection signals are detected simultaneously on the basis of a number of codes, with an associated dedicated safety and/or security level being predetermined for each protection signal.

5. The method as claimed in claim 1, characterized in that the code is a code word comprising a number of bits, and in that the code word is detected on the basis of the protection signal with optimum safety and/or security or with optimum reliability, or on the basis of a mixed form.

6. A remote tripping device for distance protection in electrical systems, having a means (2) for reception of a sequence of digital code words on a transmission channel, at least one detector (3, 5, 7) for detection of a code which corresponds to a protection signal, and at least one means for signaling that a protection signal is regarded as having been received if a code which corresponds to the protection signal is detected a total of n times in this sequence within a time window of predetermined length, characterized

in that the number n can be determined on the basis of an estimate of a measure at any given time of a disturbance on the transmission channel.

7. The remote tripping device as claimed in claim 6, characterized in that the remote tripping device has a number of detectors (3, 5, 7) which operate in parallel, in which the number n of required repetitions can in each case be set individually on the basis of the measure for the disturbance and on the basis of a safety and/or security level which is predetermined for the respective detector (3, 5, 7).