Method and device to identify, record and store traveling wave heads in electric power systems

Abstract

METHOD AND DEVICE TO IDENTIFY, RECORD AND STORE TRAVELING WAVE HEADS IN ELECTRIC POWER SYSTEMS consisting in sending a trigger ( 5 ) signal generated from the monitoring of the basic values of voltage and current of the electrical signal ( 1 ) of the transmission system in its fundamental frequency of operation (50/60 Hz), where the generated trigger ( 5 ) signal is controlled by continuous monitoring of the parameters derived from the basic values of current and voltage and tested against thresholds previously set by a user.

What is claimed is: 
     
         1 . A system for determining the location of a fault in an electric power transmission network, comprising:
 fault locating equipment configured to be coupled to an electrical line of the power transmission network, the equipment including a processing circuit configured to:
 extract frequency components of an electrical signal passing through the electrical line and related to a traveling wave caused by the fault, the electrical signal having a fundamental frequency of 50 Hz or 60 Hz; 
 isolate at least one of a voltage or a current of the electrical signal corresponding to the fundamental frequency by removing components of the electrical signal having a frequency greater than the fundamental frequency; 
 derive a parameter in the fundamental frequency from the isolated at least one of the voltage or the current of the electrical signal; 
 compare the parameter in the fundamental frequency to a threshold; 
 identify the traveling wave caused by the fault in response to the parameter in the fundamental frequency exceeding the threshold; and 
 store a sample of the electrical signal corresponding to when the parameter in the fundamental frequency exceeded the threshold to determine the location of the fault in the electrical line of the power transmission network. 
   
     
     
         2 . The system of  claim 1 , wherein the processing circuit includes a low-pass filter configured to isolate the at least one of the voltage or the current of the electrical signal. 
     
     
         3 . The system of  claim 2 , wherein the processing circuit includes an analog-to-digital converter which performs sampling of the isolated at least one of the voltage or current of the electrical signal to digitize the isolated at least one of the voltage or current of the electrical signal. 
     
     
         4 . The system of  claim 1 , wherein the processing circuit is configured to continuously monitor the parameter in the fundamental frequency. 
     
     
         5 . The system of  claim 1 , wherein the threshold is a previously set user threshold. 
     
     
         6 . The system of  claim 1 , wherein the parameter in the fundamental frequency derived from the voltage of the electrical signal includes at least one of a root mean square (RMS) value, an RMS neutral value, an RMS value of a fundamental component, an RMS value of a neutral fundamental component, a frequency, a positive sequence, a negative sequence, an imbalance, or a total harmonic distortion. 
     
     
         7 . The system of  claim 1 , wherein the parameter in the fundamental frequency derived from the current of the electrical signal includes at least one of a root mean square (RMS) value, an RMS neutral value, an RMS value of a fundamental component, an RMS value of a neutral fundamental component, a positive sequence, a negative sequence, an imbalance, or a total harmonic distortion. 
     
     
         8 . The system of  claim 1 , wherein the processing circuit is configured to derive the parameter in the fundamental frequency from a power of the electrical signal, wherein the parameter in the fundamental frequency derived from the power includes at least one of a combined apparent power, a fundamental apparent power, a fundamental active power, or a fundamental reactive power. 
     
     
         9 . The system of  claim 1 , wherein the processing circuit is configured to use Boolean equations to control generation of the trigger signal using monitoring of a plurality of thresholds. 
     
     
         10 . The system of  claim 1 , wherein the processing circuit is configured to extract the frequency components of the electrical signal by receiving the electrical signal on a first signal path, and the processing circuit is configured to store a sample of the electrical signal based on receiving the electrical signal on a second signal path separate from the first signal path. 
     
     
         11 . A method for determining the location of a fault in an electric power transmission network, comprising:
 extracting, by a processing circuit of fault locating equipment coupled to an electrical line of the power transmission network, frequency components of an electrical signal passing through the electrical line and related to a traveling wave caused by the fault, the electrical signal having a fundamental frequency of 50 Hz or 60 Hz;   isolating, by the processing circuit, at least one of a voltage or a current of the electrical signal corresponding to the fundamental frequency by removing components of the electrical signal having a frequency greater than the fundamental frequency;   deriving, by the processing circuit, a parameter in the fundamental frequency from the isolated at least one of the voltage or the current of the electrical signal;   comparing, by the processing circuit, the parameter in the fundamental frequency to a threshold;   identifying, by the processing circuit, the traveling wave caused by the fault in response to the parameter in the fundamental frequency exceeding the threshold; and   storing, by the processing circuit, a sample of the electrical signal corresponding to when the parameter in the fundamental frequency exceeded the threshold to determine the location of the fault in the electrical line of the power transmission network.   
     
     
         12 . The method of  claim 11 , wherein the at least one of the voltage or the current of the electrical signal is isolated by a low-pass filter. 
     
     
         13 . The method of  claim 12 , further comprising using an analog-to-digital converter to sample the isolated at least one of the voltage or current of the electrical signal to digitize the isolated at least one of the voltage or current of the electrical signal. 
     
     
         14 . The method of  claim 11 , further comprising continuously monitoring the parameter in the fundamental frequency. 
     
     
         15 . The method of  claim 11 , wherein the threshold is a previously set user threshold. 
     
     
         16 . The method of  claim 11 , wherein the parameter in the fundamental frequency derived from the voltage of the electrical signal includes at least one of a root mean square (RMS) value, an RMS neutral value, an RMS value of a fundamental component, an RMS value of a neutral fundamental component, a frequency, a positive sequence, a negative sequence, an imbalance, or a total harmonic distortion. 
     
     
         17 . The method of  claim 11 , wherein the parameter in the fundamental frequency derived from the current of the electrical signal includes at least one of a root mean square (RMS) value, an RMS neutral value, an RMS value of a fundamental component, an RMS value of a neutral fundamental component, a positive sequence, a negative sequence, an imbalance, or a total harmonic distortion. 
     
     
         18 . The method of  claim 11 , further comprising deriving the parameter in the fundamental frequency from a power of the electrical signal, wherein the parameter in the fundamental frequency derived from the power includes at least one of a combined apparent power, a fundamental apparent power, a fundamental active power, or a fundamental reactive power. 
     
     
         19 . The method of  claim 11 , further comprising using Boolean equations to control generation of the trigger signal using monitoring of a plurality of thresholds. 
     
     
         20 . The method of  claim 11 , wherein extracting the frequency components of the electrical signal is performed based on receiving the electrical signal on a first signal path, and storing the sample of the electrical signal is performed based on receiving the electrical signal on a second signal path separate from the first signal path.