Abstract: A method of event analysis in an intelligent electronic device is presented. The intelligent electronic device includes a microprocessor and associated memories. An algorithm (program) stored in a memory of the intelligent electronic device analyzes events of an electrical distribution system at the intelligent electronic device.

Abstract: A short-circuit distance relay has a short-circuit distance relay element that calculates a fault impedance from voltage and current which are introduced from a power system and that compares the fault impedance with a set impedance and uses the fault impedance comparison result within its protection zone. It calculates the amplitudes of the phase-to-phase differences of these voltage amplitudes and a sensitivity constant Vk.

Abstract: A disturbance locating system deployed within a power grid to estimate a location of a disturbance in a power system includes a voltage transducer, a current transducer and disturbance energy determination circuitry. The system may also include disturbance power determination circuitry. The voltage transducer couples to an output of a voltage transformer, the output of the voltage transformer representative of a voltage on a line within the power grid. The current transducer couples to an output of a current transformer, the output of the current transformer representative of the current flowing through the line, the output having a forward reference direction and a behind reference direction. The voltage and current transformers may be hard wired to the line. The disturbance energy determination circuitry couples to the voltage transducer and the current transducer.

Abstract: A method and apparatus for over current backup protection is provided. The method generates a set of root mean square (rms) values from samples that are taken from the system current. Several rms current values are averaged to generate an estimated rms over current value. The estimated over current value is compared with a predetermined threshold value. If the estimated current is above the predetermined threshold value, a fault protection mechanism, such as opening a circuit breaker, is activated. A generator protection unit having digital signal processing capabilities executes the inventive method to provide protection from over current episodes.

Abstract: As a variation of the non-orthogonal filter, a phasor estimate is computed by using an N-point window. An aspect of the sub-window cosine filter is to repeat the basic cosine filter for only selected points of the window. In the end, a least-squares fit is used to obtain an estimate for the phasors components. Previous cosine techniques use a data window whose length is greater than 1 cycle while the present invention requires only 1 cycle.

Abstract: A high sample rate cosine filter eliminates DC components by summing them such that they sum to zero. A non-orthogonal cosine filter is also provided. When the cosine filter is applied for N=4 samples per cycle, the samples are separated by 90 degrees. However, at higher sampling rates, it is not necessary to wait for 90 degrees to estimate the phasor value. Non-orthogonal components are used to estimate the phasor value. The time delay associated with the cosine filter is reduced in the process.

Abstract: In an illustrative embodiment, the AC power line network simulator includes an enclosure for containing elements of the system. An AC coupling network coupled to the network simulator implements the functions relating to a particular simulation. A distribution panel connected to a power feed distributes power and includes outgoing circuits and circuit breakers for protecting the outgoing circuits. A plurality of outlets are connected to the breakers of the panel. Through the use of the simulator, with the AC coupling network, simulation of an AC power line network, such as measuring electrical signals, recording electrical signals, simulating electrical signals and inserting electrical signals, can be easily performed. The measured, recorded, simulated and inserted signals correspond to electrical characteristics of elements found in an AC power line network, and can be stored for later analysis. In addition, once simulation information has been stored, it can be reproduced as desired.

Abstract: A software management system of an intelligent power conditioner with backup system option employing trend analysis for early prediction of AC power line failure. An AC line power conditioner utilizing a microprocessor based control system for providing suitable alarms when an operating input AC line is defective or the trend of measured deficiencies predicts line power failure and for initiating an inverter control signal when an inverter module is attached as an option. The software controlled system analyzes the input and output voltages, provides analysis of input voltage surges and sags, measures transient amplitude and transient pulse width, counts glitches and dropouts, measures frequency, and identifies each defect and computes associated trends, stores all accumulated data in a Log Buffer for digital printout, and then provides appropriate alarms to a user.

Abstract: A distributed energy storing system employing a communications network is disclosed. A distributed battery system includes a number of energy storing modules, each of which includes a processor and communications interface. In a network mode of operation, a battery computer communicates with each of the module processors over an intra-battery network and cooperates with individual module processors to coordinate module monitoring and control operations. The battery computer monitors a number of battery and module conditions, including the potential and current state of the battery and individual modules, and the conditions of the battery's thermal management system. An over-discharge protection system, equalization adjustment system, and communications system are also controlled by the battery computer. The battery computer logs and reports various status data on battery level conditions which may be reported to a separate system platform computer.

Abstract: A method and system for detecting the peak of respective half-cycles of a sinusoidal waveform. The sinusoidal waveform is rectified and only sample points above a first threshold are analyzed. The peaks of each half-cycle are only accepted if they are above a second, greater threshold. Peaks below the second threshold are not accepted. The peaks themselves are detected by starting a counter at the first sample in the rectified waveform which is above the first threshold value. Once the rectified waveform descends below the first threshold, the counter is stopped and the maximum value of the previous k samples is the peak value, where k is the counter value for the successive samples above the first threshold. The peak value so determined is rejected if it is less than the second threshold value. On the other hand, when the peak value is above the second threshold, it is averaged with the last valid peak value (above the second threshold).