Abstract: A method for recording analog signals and digitally encoded information associated with primary and secondary devices of an electric power system includes: receiving a plurality of analog output signals and a plurality of ON/OFF status signals from the electric power system; receiving a time-synchronization analog signal and/or a time-synchronization data packet from a time synchronization source; maintaining an internal clock synchronized with the synchronization source; sampling and digitizing the plurality of analog output signals; monitoring a status and/or a change of status of the plurality of ON/OFF status signals; receiving digitally encoded information signals as incoming data packets; decoding and analyzing the incoming data packets; analyzing the plurality of analog output signals and digitally encoded information signals using a triggering algorithm; and storing digitized analog output signals and digitally encoded information signals together with corresponding timing information in a record as f

Abstract: A method for detecting stator ground faults in a generator is described. The method includes receiving a neutral voltage signal from a neutral point of a stator, receiving a plurality of terminal voltage and current signals from the stator, deriving a magnitude of a harmonic component from the neutral voltage signal, deriving a total complex power from the terminal voltage and current signals, calculating an expected value of a harmonic based on the complex power at a first time and a plurality of values of the complex power, where the values of the complex power are measured at times before the first time, and comparing the expected value and a measured value of the harmonic.

Abstract: An intelligent electronic device (IED) configured to supervise a process having a state has at least one of a current, voltage or resistive input configured to monitor the state of the process, a binary status input configured to monitor the state of the process, a binary status input configured to receive a digitally encoded serial communication package for monitoring the state of the process, a control output configured to output a signal to control process protection, control, or automation, or a combination thereof, or a control output configured to output a digitally encoded serial communication package to control protection, control, or automation, or a combination thereof. The IED is also configured to facilitate digital communication between at least two compatible devices by directing communication packets from ports connected to an originating compatible device to ports connected to a destination compatible device.

Abstract: A method for distributing a timing signal to a device. The method includes receiving a timing signal from a timing source, receiving a power signal, superimposing the timing signal on the power signal to facilitate creating a different power signal to be distributed to the device, decoding the timing signal from the power signal within the device, and adjusting an internal clock of the device to facilitate synchronizing the internal clock with the decoded timing signal.

Abstract: A phasor measurement system is provided for computing synchronized phasor measurements. The phasor measurement system includes acquisition circuitry for acquiring voltage or current values from a power line, sampling circuitry for sampling the voltage or current values, and processing circuitry for computing a phasor and at least one time derivative of the phasor based on the sampled voltage or current values and for computing a synchronized phasor value based on the phasor and the at least one time derivative of the phasor.

Abstract: A method for compensating for communications channel delay asymmetry in a current differential protection system includes determining an apparent sampling clock offset for a communications channel, the apparent sampling clock offset between a first sampling clock and a second sampling clock configured within the current differential protection system. An apparent global positioning system (GPS) clock offset is determined for the communications channel, the apparent GPS clock offset between a plurality of GPS time stamps corresponding to the first and said second sampling clocks. A compensated clock offset is determined by subtracting the apparent GPS clock offset from the apparent sampling clock offset so as to cancel out a channel asymmetry component of deviation in the apparent GPS and sampling clock off-sets.

Abstract: A method and apparatus for recording analog signals and digitally encoded information associated with primary devices of an electric power system and secondary devices associated with the electric power system, the apparatus includes a hosting device configured for: receiving a plurality of analog output signals from corresponding transducers of the electric power system; receiving a plurality of ON/OFF status signals from the primary and secondary devices of the electric power system; receiving at least one of a time-synchronization analog signal from a time synchronization source and a time-synchronization data packet from the time synchronization source over a communication medium; maintaining an internal clock synchronized with the synchronization source for time synchronization; sampling and digitizing the analog output signals; monitoring at least one of a status and a change of status of the ON/OFF status signals; receiving digitally encoded information signals as data packets via a communication port;

Abstract: A method for compensating for communications channel delay asymmetry in a current differential protection system includes determining an apparent sampling clock offset for a communications channel, the apparent sampling clock offset between a first sampling clock and a second sampling clock configured within the current differential protection system. An apparent global positioning system (GPS) clock offset is determined for the communications channel, the apparent GPS clock offset between a plurality of GPS time stamps corresponding to the first and said second sampling clocks. A compensated clock offset is determined by subtracting the apparent GPS clock offset from the apparent sampling clock offset so as to cancel out a channel asymmetry component of deviation in the apparent GPS and sampling clock off-sets.

Abstract: The present invention relates to a method for locating a fault on a power transmission line which is series-compensated with capacitors. The site of the fault is determined with the aid of measured currents and voltages at one of the two ends of the power transmission line before and after the occurrence of the fault and a calculating algorithm based on impedance models of the power transmission line before and after the occurrence of the fault.

Abstract: A method and relay for magnetizing inrush restraint in protective relays for power transformers. The method utilizes the phase angle relation between the fundamental component and the second harmonic in addition to the magnitude ratio. This is accomplished by calculating and utilizing the complex second harmonic ratio. The specially shaped operating characteristic for the complex second harmonic ratio is made dynamic providing for better security without jeopardizing dependability of the transformer protective relay.