High impedance fault (HIF) detection and location accuracy is provided. An HIF has random, irregular, and unsymmetrical characteristics, making such a fault difficult to detect in distribution grids via conventional relay measurements with relatively low resolution and accuracy. Embodiments disclosed herein provide a stochastic HIF monitoring and location scheme using high-resolution time-synchronized data in micro phasor measurement units (μ-PMUs) for distribution network protection. In particular, a fault detection and location process is systematically designed based on feature selections, semi-supervised learning (SSL), and probabilistic learning.

Non-fault disturbance-based method and system for measuring short-circuit capacity of a power grid on site including: connecting or disconnecting a reactive compensation device to or from a power grid point of common coupling, to generate a disturbance on a power grid; obtaining total active power and total reactive power of a load of the point of common coupling before the disturbance; determining a vector difference between a voltage of the power grid point of common coupling before the disturbance and a voltage of the power grid point of common coupling after the disturbance; obtaining a voltage effective value of the power grid point of common coupling before the disturbance; obtaining a capacity of the reactive compensation device; and determining a short-circuit capacity of the point of common coupling according to total active power, total reactive power, vector difference between voltages, voltage effective value, and capacity of the reactive compensation device.

Non-fault disturbance-based method and system for measuring short-circuit capacity of a power grid on site including: connecting or disconnecting a reactive compensation device to or from a power grid point of common coupling, to generate a disturbance on a power grid; obtaining total active power and total reactive power of a load of the point of common coupling before the disturbance; determining a vector difference between a voltage of the power grid point of common coupling before the disturbance and a voltage of the power grid point of common coupling after the disturbance; obtaining a voltage effective value of the power grid point of common coupling before the disturbance; obtaining a capacity of the reactive compensation device; and determining a short-circuit capacity of the point of common coupling according to total active power, total reactive power, vector difference between voltages, voltage effective value, and capacity of the reactive compensation device.

Disclosed is a pollution and torque measuring device for busbar additional connection modules that detects the degree of pollution occurring in the additional connection modules that allow busbar modules to be attached to each other in electrical distribution systems known as busbars and whether the additional is tightened with sufficient torque.

System and method for characterizing material condition. The system includes a sensor, impedance instrument and processing unit to collect measurements and assess material properties. A model of the system may be used to enable accurate measurements of multiple material properties. A cylindrical model for an electromagnetic field sensor is disclosed for modeling substantially cylindrically symmetric material systems. Sensor designs and data processing approaches are provided to focus the sensitivity of the sensor to localize material conditions. Improved calibration methods are shown. Sizing algorithms are provided to estimate the size of defects such as cracks and corrosion. Corrective measures are provided where the actual material configuration differs from the data processing assumptions. Methods are provided for use of the system to characterize material condition, and detailed illustration is given for corrosion, stress, weld, heat treat, and mechanical damage assessment.

The present invention related to the field of power system protection and control, presents a voltage travelling wave differential protection method considering the influence of frequency-dependent parameters, which provides more accurate and rapid fault identification. The technical scheme of the present invention is as follows: a calculation method of voltage travelling-wave differential protection for VSC-HVDC transmission lines, taking the influence of the frequency-dependent parameters into consideration, the steps are as follows: calculating a characteristic impedance and propagation coefficient of the frequency-dependent transmission line in time domain, collecting voltage and current signals at the both ends of the transmission line and then calculating the forward and backward voltage travelling wave, respectively, comparing a differential value of voltage travelling wave with a preset threshold value to determine whether the internal fault occurs.

The present invention is mainly applied in the field of power system protection and control.

A transformer condition evaluation method combining a FAHP-DEMATEL method and a CRITIC method is provided and includes: selecting a plurality sets of condition quantities, building a hierarchical indicator system; calculating a degree of influencing and a degree of being influenced by using the DEMATEL method on a subjective level, calculating a weight of each of a plurality of indicators of an indicator layer through the FAHP-DEMATEL method, calculating the weights of the indicators of the indicator layer through the CRITIC method on an objective level; calculating an optimal weight according to the subjective weights of the indicators and the objective weights of the indicators; and calculating condition scores layer by layer, finally determining an actual health condition of each of a plurality of transformers by combining condition level classification rules. In the disclosure, the weights are calculated based on the subjective level and the objective level.

A transformer condition evaluation method combining a FAHP-DEMATEL method and a CRITIC method is provided and includes: selecting a plurality sets of condition quantities, building a hierarchical indicator system; calculating a degree of influencing and a degree of being influenced by using the DEMATEL method on a subjective level, calculating a weight of each of a plurality of indicators of an indicator layer through the FAHP-DEMATEL method, calculating the weights of the indicators of the indicator layer through the CRITIC method on an objective level; calculating an optimal weight according to the subjective weights of the indicators and the objective weights of the indicators; and calculating condition scores layer by layer, finally determining an actual health condition of each of a plurality of transformers by combining condition level classification rules. In the disclosure, the weights are calculated based on the subjective level and the objective level.

A device having an impedance measurement circuit that allows for reduction of flicker noise can be implemented in a variety of applications. A carrier suppression technique can be implemented that substantially removes the carrier signal with removal of noise artifacts associated with the carrier signal from sidebands of the carrier signal. Carrier suppression in an AC impedance measurement circuit can be implemented by sensing a carrier signal of the measurement circuit at a transmit location of the measurement circuit and subtracting a weighted version of the carrier signal at a receive location of the measurement circuit. One or more compensation impedances can be used such that the sidebands of the carrier signal are received with the carrier signal suppressed with respect to the receive location.

A device having an impedance measurement circuit that allows for reduction of flicker noise can be implemented in a variety of applications. A carrier suppression technique can be implemented that substantially removes the carrier signal with removal of noise artifacts associated with the carrier signal from sidebands of the carrier signal. Carrier suppression in an AC impedance measurement circuit can be implemented by sensing a carrier signal of the measurement circuit at a transmit location of the measurement circuit and subtracting a weighted version of the carrier signal at a receive location of the measurement circuit. One or more compensation impedances can be used such that the sidebands of the carrier signal are received with the carrier signal suppressed with respect to the receive location.