141 results about "Fault resistance" patented technology

The invention discloses a multi-terminal flexible DC power grid line direction pilot protection method. The method comprises steps: DC current and voltage at two ends of a DC reactor are measured and a DC current mutation rate di/dt and a voltage mutation rate du/dt are calculated; when the di/dt or the du/dt is larger than a threshold value K1-set and K2-set, a protection algorithm is started instantly; fault voltage at two sides of a DC reactor at a protection terminal is measured, and corresponding transient components UM_line and UM_bus (UN_line and UN_bus) are extracted; r1=UM_line/UM_bus (r2=UN_line/UN_bus) is calculated, and a fault direction is judged: if r1>1+epsilon (r2>1+epsilon), epsilon is a reliable margin, positive direction fault is judged and a direction signal RM is equal to 1 (RN=1), or otherwise, reverse direction fault is judged, and a direction signal RM is equal to 0 (RN=0); when RM&RN=1, internal fault is judged; and when RM&RN=0, external fault is judged. The method of the invention has the advantages that data synchronization is not needed; a sampling rate is lowly required; the fault resistance withstanding ability is strong; influences from line distributed capacitance do not exist; engineering implementation is facilitated; and the hardware investment cost is reduced.

A method for locating faults in three-terminal and multi-terminal power lines, applicable in electric power systems for overhead and underground cable transmission and distribution lines. The inventive method is characterised in that it measures current for fault and pre-fault conditions and in one terminal station of the system line phase voltage for fault and pre-fault conditions is measured, a hypothetical fault location is assumed, the distances to the hypothetical fault locations are calculated and fault resistance is calculated, the actual fault point is selected by first comparing the numerical values concerning the distances to the hypothetical fault locations and rejecting those results whose numerical values are negative or bigger than one in relative units, and then by analysing the values of the calculated fault resistances for the fault locations and rejecting those results of the calculations for which the value of fault resistance is negative, and if there is still more than one calculation result remains not rejected then performing selection of the valid result by analysing the values of the calculated respective equivalent source impedances.

A method and an adaptive distance protection relay for compensating for a remote line end infeed effect during determination of a distance to a resistive fault on a three-phase power transmission line. It is assumed that a fault current flows through the fault resistance. A fault loop impedance is first calculated by a known algorithm from phase voltages and phase currents. A shift of the fault loop impedance is determined from the fault loop impedance, the impedance of the transmission line for the positive current sequence and the phase angle of a complex fault current distribution factor, where the fault current distribution factor is the ratio of the fault loop current to the fault current. The distance to fault is calculated by subtracting the impedance shift from the fault loop impedance and dividing the result by the impedance of the transmission line for the positive current sequence.

The invention relates to an overvoltage protection device and method for the alternating current side of a voltage source converter high voltage direct current transmission system. The overvoltage protective device is connected to two ends of a ground resistor of the converter transformer valve side in parallel and used for acting to lead failure current away, restraining the level of overvoltage of an alternating current circuit I (4) and protecting a converter valve body (9) when overvoltage of a direct current circuit (8) exists due to a fault of the alternating current circuit I (4) or a fault of the direct current circuit (8) or a valve base controller detects the phenomenon that the alternating current circuit I (4) breaks down. The protective device is rapid in action, strong in through-flow capacity, large in absorbed energy, and capable of rapidly protecting the valve body. A control protective device with a complicated structure and complicated functions is not needed. The overvoltage protective device is simple in structure, low in cost and easy to implement, reduces the cost of the alternating current and insulation cost of a converter valve, guarantees safety of the alternating current circuit and the converter valve, improves fault-resistance ability of a converter station, and guarantees safe and stable operation of the voltage source converter high voltage direct current transmission system.

The invention discloses a real-time message exchange platform and a distributed cluster establishment method. The platform includes an application server cluster and a data server cluster. The application server cluster and the data server cluster are in communication connection through a gigabit local-area network. The platform has the advantages that any quantity of loads (common/ gateway) and load balances are supported so that expandability of a system is greatly strengthened; on-line-user supporting capacity of the system is greatly strengthened through service resources provided by a large quantity of nodes; system operation and maintenance cost is reduced by not limiting start sequence of the nodes; through dynamic cluster entrance and exit of the nodes and automatic reconstruction of a system cluster network, a system dynamic expansion capability is increased, system stop time is reduced and system operation and maintenance cost is reduced; and through distributed storage of data, supporting capability for large-capacity data and system-fault resistance capability of the system are improved.

A method for determining the nature of a ground fault in a floating direct voltage load powering context includes measuring the load voltage and the current at a nominal balance point, both before and after closing a circuit to the load. The fault resistance and the fault voltage are determined as the solution to an equation in two unknowns given the conditions before and after application of load voltage or at least precharge.

The invention discloses a main base station of submarine observation network based on a constant-current power supply. The main base station is connected in series in a backbone network submarine cable. The main base station is connected with a shore base station and an adjacent main base station through a submarine cable terminal box. The main base station comprises an underwater power supply anda communication control module. The underwater power supply is used for converting a constant-current power supply provided by a shore base station into a power supply of the main base station and aplurality of backup power supplies, outputting a direct-current constant-voltage power supply to the communication control module, and controlling the main base station to be networked and offline. The communication control module is used for monitoring the internal state of the main base station in a master control backup manner and sending the state information and data uploaded by the externalequipment to the shore base station. The communication control module is also used for receiving an instruction of the shore base station to perform fault isolation when the internal state has a fault. The main base station of submarine observation network based on the constant-current power supply has the advantages of high power and high reliability. The problems that a constant-voltage power supply type main base station is poor in submarine cable fault resistance and poor in robustness are solved.

The invention relates to a device for testing a fault of satellite on-board software, and discloses a device for testing the single event upset fault resistance of on-board software, which comprises an on-board data managing computer (2), an on-board computer run testing environment (3), a remote injected data receiving device (4), a telemetry data processing device (5) and a fault simulating module (1), wherein the on-board data managing computer (2) is used for running on-board control software; the on-board computer run testing environment (3) is used for observing the danger of the occurrence of the single event upset fault of the on-board software and the time of the fault recovery; the remote injected data receiving device (4) is used for receiving a command, data and a program from the ground; the telemetry data processing device (5) is used for displaying the run state and the fault record of the on-board software; and the fault simulating module (1) is used for automatically simulating a single event upset fault event in a timing manner. The invention solves the problem of on-board apparatus fault test and the single event or electromagnetic pulse jamming, thereby realizing the purposes of evaluating the effectiveness of the measure of resisting the single event and improving the enhancement of the on-board software.

A high-speed disk drive system that features significant performance improvements over previously available systems. By immediately fetching the data as soon as heads reach the destination cylinder, internally stripping the data across the surfaces and plurality of read/write heads on every surface the data transfer speeds many times depending on other characteristics of the system. By implementing plurality of read/write heads and internal parity surfaces or distributed parity blocks/zones the system achieves higher reliability (fault resistance) with head and surface fail-over fail-safing.

The invention discloses a complex power grid fault location method based on wide-area travelling wave energy and time difference. According to the fault location method, by starting from travelling wave energy generated after failure of a power grid, the influence of line length and bus out-degree on the attenuation of travelling wave energy in the process of transmission in the power grid is analyzed, the three-phase current of each substation after failure is measured, the magnitude of travelling wave energy of each substation is calculated, and thus, a fault section and a fault point are determined. A lot of existing equipment is used in the method. The method requires low real-time performance of data sampling, and is easy to implement. Through analysis of a simulation model built according to actual parameters, the method is not affected by fault phase angle and fault resistance, and is of high accuracy and robustness. The positioning method of the invention is suitable for application in a complex power grid.

The invention discloses a device and a method for testing a power cable fault. The device for testing the power cable fault comprises a high voltage part and a detection control part; the detection control part comprises a potentiometer and a detection and control circuit; two fixed ends of the potentiometer are connected with any two phases of a tested cable; one phase is a faulted phase; the sliding end of the potentiometer and the fault test current collection end of the detection and control circuit are connected with the output of the high voltage part; the control end of the detection and control circuit is connected to the sliding end of the potentiometer; and the detection signal end of the voltage at both ends of a test bridge of the detection and control circuit is isolated from the high voltage part and connected in parallel with the two fixed ends of the potentiometer. By the test method in which the high voltage part is isolated from the detection and control part, an operator can exert high voltage in a higher range to the tested faulted cable by regulating a voltage regulator on the low voltage side safely and reliably, so the tested fault resistance value is large, and the fault test range is enlarged greatly.

Disclosed is a mixed type method of multi-terminal circuit fault location. The method comprises the following steps: step 1, symmetrical component voltage of a fault point is calculated according to symmetrical component voltage and current of a sending terminal; step 2, the symmetrical component voltage of the fault point is calculated according to symmetrical component voltage and current of a receiving terminal; step 3, delta is supposed to be a phase angle of the sending terminal lagging behind the receiving terminal, d is supposed to be the fault distance, and the phase angle displacement delta and the fault distance d are obtained through an iteration mode by using weighted least squares (WLS); step 4, sequence voltage and phasor voltage of a fault position can be measured and calculated from voltage and current at two terminals according to obtained fault points and phase angle difference; step 5, a threshold value Ith is set through the sum of the fault current and a pre-confirmed constant C, and the type of a fault is confirmed; and step 6, fault resistance is obtained by calculating the current and the voltage of the fault position.

The invention discloses a transmission line iterative distance measuring method based on a zero-mode traveling wave velocity variation characteristic, belonging to a method of grid line fault positioning. After a fault occurs on a transmission line, a transient traveling wave is propagated on the line. According to the method, starting from propagation characteristics of the traveling wave on theline, the relationship between a traveling wave propagation distance and a traveling wave velocity is analyzed, and a function formula between a zero mode and a fault distance is obtained through least square fitting. Combined with a wave speed-distance formula and a time difference of a zero mode and a line mode at two ends of the line, with maximum and minimum zero mode wave velocity on the lineas an initial condition, a modulus time difference formula is substituted, and a precise fault point is positioned through iteration. According to the method, the synchronization of two ends of the line is not needed, the method is not influenced by factors of a system load and fault resistance, traveling wave measuring devices in substations at two ends of the line are used, and the realizationis convenient. The positioning precision is high, and the speed is fast. The positioning method of the invention can be used in trans-regional remote distance high-voltage power transmission line.

In order to provide a communication system and a communication system processing method with which fault resistance is improved and also signal loopback can be prevented, a communication system is provided with, for example, port switches SWP1 to SWP3, fabric switches SWF1 and SWF2, and user switches SWU1 and SWU2, and SWP1 and SWP2 are connected by a common communication line between redundancy ports Pr to thereby form the same domain group (MLAG) and logically function as one switch. Each of SWF1 and SWF2 sets, for ports P1 and P2 to which SWP1 and SWP2 that are constituent elements of the same domain group are connected, a sublink SLK that causes the ports P1 and P2 to logically function as one port.

The invention discloses a stocking system. A preordering passage is connected between a warehouse discharge line body and a conveying line body and consists of one group or more than one group of conveying passages parallelly connected between the conveying line body and the warehouse discharge line body, the conveying line body conveys cargos ordered according to the warehouse discharge sequence into the corresponding group of conveying passages in the preordering passage, the corresponding group of conveying passages store the cargos ordered according to the warehouse discharge sequence, when the sorting line cargo ordering instructions from a corresponding sorting line are received, the cargos ordered according to the warehouse discharge sequence are sequentially pushed to the warehouse discharge line body according to a first-in first-out principle, and the cargos ordered according to the warehouse discharge sequence are conveyed to the corresponding sorting line by the warehouse discharge line body. Simultaneously, the invention also discloses a stocking method, when the system and the method disclosed by the invention are adopted, the influence on the subsequent sorting process flow caused by abnormal conditions in the stocking process is reduced, and the fault resistance and interference resistance capability of the stocking system are improved.

The invention discloses an accurate fault locating method for double circuit lines on the same pole, which is used for solving the problems of locating errors caused by unavailability of avoiding mutual impedance and mutual susceptance phase difference among leads and the realization of fault location in any fault existing in the conventional fault locating method for double circuit lines on the same pole. According to the accurate fault locating method, an accurate fault calculation method is adopted. The accurate fault locating method comprises the following steps of: 1, calculating measured values of current and voltage vectors before and after a fault with a Fourier algorithm; 2, calculating impedance matrixes and potentials of systems on both sides; 3, calculating to obtain a transfer matrix ranging from fault points of the double circuit lines on the same pole to a bus by using different fault distance values with a feature modulus decomposition method; 4, constructing a resistance matrix of the fault points by using different fault resistance values; 5, solving an equation to obtain calculated values of voltage vectors of buses on both sides and current vectors from a circuit to a bus; and 6, calculating an error quadratic sum of each vector calculated value and measured value. In different values of a fault distance and fault resistance, the error quadratic sum calculated by using a fault distance and a fault resistance value which are most proximate to a practical fault distance and practical fault resistance in the step 6 is least.

The invention relates to the technical field of distribution network relay protection and more particularly relates to a single-phase ground fault detection method based on a line equivalent impedancevalue. With a condition that a ratio of a zero sequence voltage power frequency effective value to a zero sequence current power frequency effective value of a fault line is much smaller than that ofa non-faulty line as a basis, by collecting the zero sequence voltage of a bus and the zero sequence current of a feeder, the ratio of the zero sequence voltage power frequency effective value to thezero sequence current power frequency effective value of the line is calculated, and whether the line has a single-phase ground fault is judged according to the size of the ratio. According to the method, the fault line and the non-faulty line can be correctly judged, the influence of a transition resistance is small, the method has good applicability to linear fault resistance and nonlinear fault resistance and is not affected by the polarity of a transformer, the sensitivity of protection to a single-phase high-impedance ground fault can be improved, the safety and stability of a power distribution network are improved, and the probability of a safety accident caused by the high-resistance ground fault is reduced.

The invention discloses a time domain model identification pilot protection method suitable for a wind power system. The method comprises the following steps: collecting three-phase voltage and current at the protection installation place and forming differential voltage and differential current; judging whether to start time domain model identification pilot protection according to the differential current value; calculating each phase of differential current and correlation coefficient rho of a first-order derivative of the differential voltage obtained after zero sequence compensation; judging internal and external faults by comparing the value of each correlation coefficient rho with a set threshold value; if the correlation coefficient rho of any phase is smaller than the set threshold value, judging that the fault is the internal fault, and then, pilot protection at the two ends of a line is carried out to protect the device to act reliably; or otherwise, judging that the fault is the external fault so as protect the device not to act reliably. The time domain model identification pilot protection method is easy to realize, can carry out split-phase judgment, is fast in action speed, is not influenced by line distributed capacitive current and fault resistance, and can be widely applied to the wind power system.

The invention discloses a split backup method of an Internet of Things access point. The method comprises the following steps: obtaining a backup access point of a first access point, and backing up cache data of the first access point in the backup access point; when it is detected that the first access point is faulty, using a third access point as the backup access point of a second access point; dividing Internet of Things terminals or relays connected with the first access point into a first set and a second set, and switching the Internet of Things terminals or relays in the first set to the second access point, and switching the Internet of Things terminals or relays in the second set to the third access point. By adoption of the split backup method, the paralysis of the Internet of Things caused by the fault of the access point can be avoided, and the fault resistance of the Internet of Things is improved.

The invention discloses a power transmission line fault type identification method based on a deep learning LSTM model. The method specifically comprises the steps: obtaining a three-phase fault current sampling sequence after a power transmission line has a fault; making a data set containing a plurality of samples, wherein each sample contains a three-phase current sampling sequence and a faulttype label corresponding to a power transmission line fault; establishing a power transmission line fault classification model based on a deep learning LSTM network, and performing forward propagationoutput; performing back propagation training on the model through a loss function; verifying, testing and storing the power transmission line fault classification model obtained by training; and taking the three-phase fault current sampling sequence of the power transmission line to be subjected to fault classification as the input of the model so as to obtain the fault type. According to the method, the limitation that features are difficult to extract in the conventional power transmission line fault classification algorithm can be overcome, and the method has better performance and is notaffected by factors such as fault positions, fault resistance and initial phases.