A current sense system may include a relay, a load conductor, and an integrator sub-circuit. Current may be provided to an electrical load via the load conductor and a latch of the relay. The current carried via the load conductor may induce a sense voltage in a coil of the relay. Based on the sense voltage induced in the relay coil, the integrator sub-circuit may determine a load sense voltage that indicates a level of the current carried via the load conductor. In some implementations, a current indication module may provide an indicator signal based on the load sense voltage. In addition, the indicator signal may be provided to additional components or devices, such as a relay controller configured to activate the latch. In some implementations, the relay controller may be configured to open the latch based on the current level described by the indicator signal.

Systems and methods for detecting faults in a power distribution network are described. In an aspect, the systems and methods determine a probability that each node of the network is powered and a probability that each distribution line in the network is faulted. In another aspect, the systems and methods determine the probabilities by transmitting a signal over a power distribution network with an active sounding system. In an additional aspect, the systems and methods determine the probabilities by utilizing collected data coupled to the power distribution network.

The present invention discloses A method of single-phase-to-ground fault line selection for a distribution line based on the comparison of phase current traveling waves, comprising: sampling three phases current traveling waves on the distribution line, and taking the busbar pointing to the line as the current positive direction; when a single-phase-to-ground fault occurs on the distribution lines, comparing the amplitude and polarity of the difference between the three phases current traveling waves before and after the fault, wherein when the amplitude of one of the three phases current traveling wave is higher than 1.5 times of the amplitude of the other two phases current traveling waves, and the polarity of the one of three phases current traveling wave of the largest amplitude is opposite to the polarity of the other two phases current traveling waves, it is determined that the fault occurs on the load side of the measuring point of the line, and the phase with the largest amplitude of the current traveling wave is the fault phase; if the difference of the amplitudes of the three phases current traveling waves is within a predetermined value and the polarity is the same, it is determined that the fault occurs on the power source side of the measuring point of the line. By the technical solution of The present invention, the precise line selection of the single-phase ground fault of the distribution line can be realized.

An AC/DC leakage detection method, which supports the detection of DC leakage and AC leakage. A DC leakage current and a low-frequency leakage current are measured by means of magnetic modulation technology, an AC signal is measured in the form of pure induction, and two detection modes are performed in a time-sharing manner. A collected leakage signal is converted into a digital signal through an AD converter. By means of the method of the present invention, the processing of a leakage signal is divided into three channels for respectively processing DC leakage, low-frequency AC leakage, and high-frequency AC leakage. The overall effective value of residual current is calculated by integrating results of DC detection and AC detection. The method of the present invention supports the detection of a suddenly increased current; and when there is a suddenly increased current, detection mode switching is performed by detecting the current sudden change of the current.

A current signal segmentation algorithm is provided. The segmentation algorithm divides a current signal waveform into mutually different segments according to a physical feature thereof, extracts shape distribution, statistical and harmonic features of the segments, and calculates a similarity between a segment pair. The segmentation algorithm includes the following steps: segmenting a current signal to separate a standby current and an overshoot current, only leaving a working current; extracting a shape distribution feature of a working current segment; extracting a statistical feature of the working current segment; extracting a harmonic feature of the working current segment; calculating a similarity between a segment pair; and deriving a maximum clique set in a similarity graph through a maximum clique search algorithm as a class from automatic segmentation. The algorithm can quickly and accurately classify current signals generated by different electrical appliances in different working states so as to facilitate subsequent processing.

A current signal segmentation algorithm is provided. The segmentation algorithm divides a current signal waveform into mutually different segments according to a physical feature thereof, extracts shape distribution, statistical and harmonic features of the segments, and calculates a similarity between a segment pair. The segmentation algorithm includes the following steps: segmenting a current signal to separate a standby current and an overshoot current, only leaving a working current; extracting a shape distribution feature of a working current segment; extracting a statistical feature of the working current segment; extracting a harmonic feature of the working current segment; calculating a similarity between a segment pair; and deriving a maximum clique set in a similarity graph through a maximum clique search algorithm as a class from automatic segmentation. The algorithm can quickly and accurately classify current signals generated by different electrical appliances in different working states so as to facilitate subsequent processing.

The present specification provides a method and device for determining a disturbance condition in a power transmission line. The method includes obtaining (302) a plurality of sample values corresponding to an electrical parameter measured in each phase. The method further includes determining (304) a plurality of magnitudes of the electrical parameter corresponding to each phase based on the corresponding plurality of sample values and determining (306) a plurality of difference values for each phase based on the corresponding plurality of magnitudes. The method includes processing (308) the plurality of difference values using a machine learning technique to determine the disturbance condition. The disturbance condition is one of a load change condition, a power swing condition and an electrical fault condition. The method also includes performing (310) at least one of a protection function and a control function based on the disturbance condition.

The present invention provides a measurement circuit and a measurement method. In the measurement circuit, a comparison unit is configured to compare a first preset value and a second preset value to obtain a voltage difference, an accumulation and subtraction unit is configured to perform counting according to a comparison result, and a control unit is configured to adjust the voltage difference between two compared voltage input terminals, thereby calculating a voltage resolution of the control unit, avoiding the impact of the actual error of the first constant current source and the unit resistor on the actual voltage resolution, and ensuring the measurement accuracy. In addition, an accurate to-be-measured voltage is calculated, and a measurement value of the to-be-measured voltage is corrected, to ensure the high measurement accuracy of the to-be-measured voltage and the output power.

The present invention provides a measurement circuit and a measurement method. In the measurement circuit, a comparison unit is configured to compare a first preset value and a second preset value to obtain a voltage difference, an accumulation and subtraction unit is configured to perform counting according to a comparison result, and a control unit is configured to adjust the voltage difference between two compared voltage input terminals, thereby calculating a voltage resolution of the control unit, avoiding the impact of the actual error of the first constant current source and the unit resistor on the actual voltage resolution, and ensuring the measurement accuracy. In addition, an accurate to-be-measured voltage is calculated, and a measurement value of the to-be-measured voltage is corrected, to ensure the high measurement accuracy of the to-be-measured voltage and the output power.

A demarcating system for indicating the boundary of an area to an object (for example a robot, such as a robotic lawnmower), which has a receiver for receiving electromagnetic signals. The system includes a control system, a wire loop, a signal generator, and current sensing circuitry. The wire loop can be arranged by a user along a path, so as to indicate the path to the object as part of a boundary of the area. The signal generator is electrically connected to the wire loop in order to apply voltage signals thereto, such signals causing the emission of corresponding electromagnetic boundary indicating signals from the wire loop that may be received by the receiver of the object. The signal generator is under the control of the control system with the voltage signals applied by the signal generator to the wire loop being controlled by the control system. The current sensing circuitry senses current signals present within the wire loop and the processors of the control system analyse such current signals. The processors of the control system are programmed to operate in a calibration mode whereby they: cause the signal generator to apply a series of test voltage waveforms to the wire loop, each of the test voltage waveforms generating a corresponding current waveform within the wire loop; and analyse the series of corresponding current waveforms, as sensed by the current sensing circuitry, so as to determine an operating voltage waveform that, when applied to the wire loop, generates a corresponding operating current waveform that is substantially the same shape as a predetermined current waveform.