171 results about "Shielding Failure" patented technology

The invention discloses a method for measuring a lightning shielding failure trip-out rate of a high-voltage power transmission line by combining topography. The method comprises the following steps of: acquiring related parameters of the power transmission line, dividing the power transmission line into a plurality of intervals according to a pole tower, dividing each interval into a plurality of small sections by adopting an equal division method, calculating longitude and latitude coordinates of each section and an auxiliary point vertical to each section through longitude and latitude coordinates of the pole tower, further acquiring altitudes of each section and the auxiliary point by adopting geographic information system software, finally calculating a ground inclination angle of each section according to the height difference and distance between the auxiliary point and the subsection point, and calculating the shielding failure trip-out rate of each section by using an electric geometrical model considering the striking distance coefficient and the ground inclination angle. The method can conveniently calculate the ground inclination angle at the pole tower of the power transmission line, reflect the actual topographical characteristics of a corridor of the power transmission line, and provide reliable basis for evaluating the lightning protection effect of a lightning wire of the power transmission line.

The invention discloses an on-line transmission line lightning shielding failure trip early-warning method. The method comprises the following steps of: performing statistics on historical lightning shielding failure trip information to obtain transmission line lightning shielding failure trip probability distribution by a two-dimensional information diffusion theory and a conditional probability method; selecting radar forecast data, such as echo intensity, echo tops and vertical accumulated liquid water content; establishing a lightning current magnitude prediction model based on a back propagation neural network; and sending real-time early warning and an early warning grade of transmission line lightning shielding failure trip probability according to the predicted lightning current magnitude and the side distance to lightning stroke and by virtue of the transmission line lightning shielding failure trip probability distribution model. According to the real-time forecast data of a meteorological radar, the method provided by the invention can predict the trip probability of a transmission line and send an early warning signal, thereby providing reference for decision-making analysis of grid dispatching operators, making a transmission line dispatching strategy in time, improving power supply reliability, lowering economic loss of a grid, and improving the reliable running ability of the grid.

The invention provides a method for determining insulation and lightning impulse withstanding properties of a same-tower double-loop power transmission line. The method comprises the following steps: determining the same-tower double-loop power transmission line to be determined, acquiring statistical parameters of lightning activities in an area in which the power transmission line is located and structural parameters of each pole tower and determining a lightning strike calculation cycle number Nl; sampling random parameters during a lightning strike process and determining lightning current amplitude, transient power frequency voltage and determination result that the lightning strike is shielding failure or back striking; judging whether tripping occurs in the pole tower after the certain lightning strike or not and carrying out statistics on the tripping times during the Nl lightning strikes according to the lightning current amplitude, the transient power frequency voltage and the shielding failure or back striking determination result, as well as the structural parameters of the pole tower, and calculating the lightning strike tripping rate; and determining the insulation and the lightning impulse withstanding properties of the power transmission line according to the lightning strike tripping rate and a target value. The determination method provided by the invention is small in error, high in precision and specific; and by adopting the determination method, design, operation and improvement of lightning protection measures of the same-tower double-loop power transmission line of an electric power department can be scientifically guided.

The invention relates to a traveling wave analysis and recognition method for distinguishing lightning shielding failure from lightning counterattack of direct current transmission line. The lightning shielding failure of line is that lightning avoids the lightning shield line and directly strokes on the transmission line, while lightning counterattack of line is that lightning directly strokes on the lightning shield line or the tower. Because the earth resistance of tower exists, the potential on tower top suddenly increases and causes insulation flashover. The electromagnetic transient component generation mechanism of the high voltage direct current transmission line and the propagation path of lightning electromagnetic transient of the line in the lightning shielding failure are different from those in the lightning counterattack, the size and polarity of the initial surge voltage and the second surge voltage of the voltage transient signal exist significant difference. The traveling wave analysis and recognition method of the invention analyzes zero mode voltage using wavelet and distinguishes the lightning shielding failure and lightning counterattack failure according to the size and polarity of the initial surge voltage and the second surge voltage of the zero mode voltage in the traveling wave analysis and high-speed acquisition system of the protection zone. A lot of simulation results show that the method is reliable and effect. The physical concept of the invention is visible and clear, the method is easy to achieve and wide to use in the direct current system protector, also provides accurate initial data for researching lightning characteristics, analyzing lightning accident, discussing lightning protection countermeasure of transmission line and designing insulation coordination in the power system.

The invention relates to a high voltage DC power transmission line shielding failure current waveform inversion recovery method. When the transmission line suffers the lightning stroke, the transient state traveling wave is spread and transmitted by the power transmission line, so the transient response at the protection installation place is different. The transmission line is equivalent to a natural lightning current air-termination system, and when the shielding failure happens, the prior traveling wave fault location technology can precisely locate the lightning stroke point; the parameters of the power transmission line can be obtained by measuring and analyzing on line; and with the transfer function of the transmission line deduced by the method, the lightning current waveform at the lightning stroke point can be finally obtained by carrying out the phase amplitude transformation, noise reduction, and Prony fit process, and deconvolution operation of on the transient voltage which is obtained through a high-speed collection at the protection installation place of the transmission line.

The invention relates to a method for identifying properties of lightning faults of an overhead line on the basis of the interval distribution of lightning current amplitude and belongs to the technical field of a high voltage. After the overhead line has a lightning tripping fault, fault information such as a grounding resistance of a fault tower, characteristic parameters of a tower rod, positioning information of a lightning monitoring system, topographic parameters and the like are collected; according to a circuit lightning protection performance algorithm and a shielding failure electrical geometric model principle, the counterattack lightning withstand level of the circuit suffering from lightning stroke and the amplitude distribution interval of the shielding failure critical lightning current are calculated by integrating a statistics rule of structural parameters of the tower and the line; and finally, the occurrence probabilities corresponding different lightning fault types of the line are obtained by utilizing a line lightning fault property judgment probabilistic algorithm model. According to the invention, the objective and reliable lightning fault type occurrence probabilities are obtained by utilizing the lightning fault property judgment probabilistic algorithm model; a judging result contains a certain fault-tolerant margin; the aims that information amount required by the lightning fault property judgment is small and the fault information is easy to acquire by operation and maintenance personnel of the line are fulfilled; and the judgment method is simple and rapid and has strong practicality.

The invention relates to a method for recognizing the shielding failure and the counterattack of a high-voltage DC transmission line. The shielding failure of the line means that the thunderbolt directly strikes on the transmission line by steering clear of a ground wire; the counterattack means that the thunderbolt directly strikes on the ground wire or a pole tower, the electric potential on the top of the tower increases instantaneously, which causes the insulation flashover due to the existence of a pole tower earth resistor. The different theories generated by the electromagnetic transient component of the shielding failure and the counterattack of the high-voltage DC transmission line and different paths of transmission of the thunderbolt electromagnetic transient component on the circuit cause that the energy distribution of different frequency bands of the generated voltage transient state signals are different greatly. In a travelling wave analysis and high-speed acquisition system at the protective installation position, the small wave analysis is adopted to extract the energy of the zero modulus voltage in different frequency bands. The shielding failure and the counterattack are differentiated according to the property of the energy distribution. A large amount of emulations show that the method is reliable and effective. The method has intuitive and clear physical concepts, is easy to implement, can be widely applied to a high-voltage DC system protective device, provides important data for the lightening protection design of the line and provides reference for the operation and maintenance of the line.

The invention relates to a method for judging the failure properties of shielding failure and counterattack of a transmission line. In the method, a computer is adopted to collect and process data; and for a certain lightning tripping failure of the transmission line, a lightning protection simulation analysis program is adopted and the collected and processed data is applied by the analysis of the computer to perform simulation reduction and comparison analysis on a circuit-failing tower with the lightning tripping to obtain a judgment result based on the data of the transmission line provided by a running unit, circuit tripping failure data and the lightning activity information of a line corridor obtained by the query of a lightning positioning system. The method comprises the following basic steps of: (1) performing collection and clearing-up on the data of the transmission line and the circuit tripping failure data by adopting the computer; (2) querying the lightning activity information in the corridor of the failing tower by utilizing the lightning positioning system; (3) analyzing the lightning protection performance of the failing tower by the computer by utilizing the lightning protection simulation analysis program; and (4) checking the lightning protection performance and judging the failure property. The method is simple, convenient and easy to operate and convenient to popularize and apply, and ensures low cost.

A method for determining a lightning hazard distribution of a power network, includes: deriving a shielding failure lightning hazard distribution of the power network and a back flashover lightning hazard distribution of the power network from the number of ground lightning in each grid and ranges of hazardous currents, and deriving a historical lightning hazard distribution of the power network from a lightning faults database of the power network and the grids; and determining the lightning hazard distribution of the power network by integrating the shielding failure lightning hazard distribution of the power network, the back flashover lightning hazard distribution of the power network and the historical lightning hazard distribution of the power network.

A method for identifying a lightning fault of an overhead transmission line (OTL) comprising determining a polarity of a travelling wave of each of three ABC phases subsequent to a single phase outage of the OTL. If the polarity of each phase is the same, the outage is a lightning fault and its type a back flashover; if not the same, proceed to the second step to determine a current change rate R of the fault phase. If R is larger than a threshold value, the outage is a lightning fault and its type a shielding failure; otherwise, the outage is a single-phase grounding fault. A system for identifying the lightning fault which comprises successively at least a group of fault detectors, a wireless communication module, a remote monitoring master station which adopts the above method to determine the fault type of the overhead transmission line.

The invention discloses a method for simulating lightning trip-out rates of a 500kV transmission line with four circuits on the same tower. The method comprises the following steps of: getting information of the tower, wherein the information of the tower comprises the height of a cross arm, an equivalent radius of a tower body and the width of the cross arm; establishing a multi-wave impedance model according to the information of the tower; establishing an insulator flashover criterion model based on an EPRI (Electric Power Research Institute) pilot model; establishing a horizontal lighting-resistant simulation model of the transmission line according to the multi-wave impedance model of the tower and the insulator flashover criterion model; adjusting a phase angle of a power supply and a simulated lighting current amplitude in the horizontal lighting-resistant simulation model of the transmission line, and then obtaining the lighting trip-out rate of each circuit of the transmission line, wherein the lighting trip-out rates comprise back flashover trip-out rates and shielding failure trip-out rates. By adopting the method for simulating lightning trip-out rates of the 500kV transmission line with four circuits on the same tower disclosed by the invention, lighting trip-out rates of the transmission line can be calculated accurately, so that security and power supply reliability of power grids are improved.

The invention provides an identification method of a lighting shielding failure of an electric transmission line. The identification method is based on waveform characteristics of traveling wave current in on-line monitoring electric transmission line phase conductors and mainly includes performing on-line monitoring to the traveling wave current, extracting data of lightning stroke failure traveling wave current on a guide line, analyzing the waveform characteristics of the lightning stroke failure traveling wave current and determining that the electric transmission line has a lightning shielding failure if a section prior the maximum traveling wave current amplitude value responds to a like polarity small pulse which is directly connected with a main discharging pulse and the pulse response duration and the current amplitude value are within certain ranges. Compared with identification methods in prior art, the identification method is explicit in judgment thoughts and tested and verified by field data, so that the identification method is capable of accurately and effectively identifying whether a waveform current signal is a signal of the lighting shielding failure electric transmission line, effectively helping electric transmission line operating maintenance departments to judge lighting stroke failure properties of the line and know lightning stroke failure reasons, and scientifically guiding line lightning protection reconstruction.

The invention discloses a comprehensive lightning protection system of electric transmission lines of a high tower of a power grid. The comprehensive lightning protection system comprises a transformer substation, a grounded multi-stage surge-preventing device and the three-phase electric transmission lines connected with the power grid are led out of a three-phase port of the transformer outbound end of the transformer substation, each phase line of the three-phase electric transmission lines is connected with a voltage isolator in series, the electric transmission lines connected with the power grid and led out of the output ends of the voltage isolators are connected with the high tower, thunder and lightning arresters are arranged at the top of the high tower and connected with a maintainable ground grid embedded below the tower through the metal tower body, the overhead electric transmission lines are supported through all phase insulator strings connected to the tower in a suspended mode, two sides of the insulator string supporting each phase line are respectively provided with a nanometer magnet resistor, and lightning conductors are arranged at the top of the tower in a supported mode. By means of the technical measures, the multilevel, omni-directional and three-dimensional comprehensive lightning protection system which makes high tower protection as the center, attaches equal importance to thunder and lightning counterattack resistance and thunder and lightning shielding failure resistance and conducts omni-directional thunder and lightning protection on the electric transmission lines and the transformer substation is built, and the lightning trip-out rate can be reduced obviously.

The invention provides a differentiation method of lightening back flashover and lightening shielding failure on an electric transmission line. The method is used for differentiating lightening references when travelling wave protection and fault location, and includes firstly differentiating the back flashover on the electric transmission line according to differences and similarities of three-phase travelling wave polarities, and then providing a differentiation method of the shielding failure on the electric transmission line based on travelling wave correction energy ratio in a short window through the travelling wave energy variations when the electric transmission line is suffered from the shielding failures and the faults. The differentiation method is clear in differentiation basis, lightening interferences on the electric transmission line can be accurately differentiated, and types of the interferences can be judged.

The invention discloses a method for optimally selecting lightning protection measures for power transmission lines on the basis of entropy weight processes. The method includes collecting informationrequired for computing lightning trip-out rates of the power transmission lines; computing the lightning trip-out rates of each tower of the power transmission lines; combining the lightning trip-outrates with lightning risk grade evaluation and dividing lightning risk grades of the various towers; combining the lightning risk grades with trip-out conditions of the power transmission lines in previous years and determining the towers required to be subjected to lightning protection transformation; building lightning protection measures optimal selection comprehensive analysis models for thetowers; determining evaluation indexes of the lightning protection measures for the towers; classifying shielding failure and back striking trip-out rates of the towers, topography and landform characteristics, structural characteristics of the towers and original insulation levels of the towers; determining weight coefficients by the aid of the entropy weight processes; empowering the evaluationindexes; comprehensively evaluating the lightning protection measures in different types of towers.

The invention relates to a shielding element and an electrical connector plug using the same. The shielding element comprises a shielding sleeve and a clamping sleeve, wherein the clamping sleeve is used for clamping a shielding layer of a cable, and is conductively connected with the shielding layer of the cable; cable channels communicated with each other are formed on the shielding sleeve and the clamping sleeve; the front end of the shielding sleeve is provided with a contact part for conductively connecting an electrical connector shell; the clamping sleeve comprises a permanent seat integrally connected to the rear end of the shielding sleeve and a pressing plate for buckling with the permanent seat to clamp the shielding layer of the cable inserted into the cable channels; and a tile-shaped concave surface is formed on at least one of the pressing plate and the permanent seat. The shielding element provided by the invention can be sleeved to the tail end of an electrical connector, conductively connected with the shielding layer of the cable by the clamping sleeve and conductively connected with the electrical connector shell by the shielding sleeve, so the shielding layer of the cable can be effectively connected by the electrical connector shell and prevented from shielding failure at the wiring position of the electrical connector, thereby effectively solving the problem that the conventional electrical connector cannot prevent lightning.

The invention provides a power distribution network lightning disaster failure prediction method. The method comprises the steps that a lightning partition is determined based on multiple times of forecasts of lightning ranges; the direct stroke ground lightning probability and the lightning induction overvoltage occurrence probability of circuits where poles and towers are located are determined; the lightning stroke tripping probability is determined according to the lightning shielding failure tripping probability and the beat back tripping probability of the circuits where the poles and towers are located; the lightning induction overvoltage tripping probability of the circuits where the poles and towers are located is determined according to the induced overvoltage maximum value of wires, the lightning induction overvoltage failure rate of the circuits where the poles and towers are located is obtained by establishing a fuzzy mathematical model, and therefore the lightning induction overvoltage tripping probability of the circuits where the poles and towers are located is obtained, wherein the lightning current intensity is taken into consideration; by establishing a power distribution circuit temperature model, the instantaneous failure probability of a feeder section in an area to be detected is determined according to the service duration of power distribution circuits; a power distribution circuit lightning disaster power distribution circuit failure probability model with aging failure and correction taken into consideration is established; the failure probability of the feeder section in the area to be detected is predicated.

The invention provides a thunder damage protection risk automatic assessment method for a power transmission line. The thunder damage protection risk automatic assessment method comprises the steps of collecting parameters of a typical pole tower and recording values of parameters comprising thunder parameters, pole tower parameters, landform parameters, line parameters and cloud-to-ground lightning parameters; establishing a back striking calculation model and a shielding failure calculation model according to the parameters of the typical pole tower; calculating the shielding failure trip-out rate n1 of the pole tower on the basis of electromagnetic transient calculation program and according to the parameters of the typical pole tower and the shielding failure calculation model; calculating the pole tower shielding failure trip-out rate n1=NgP1eta on the basis of a guiding developing model; calculating the average lightning stroke trip-out rate N according to the back striking trip-out rate n1 and the shielding failure trip-out rate n2; and performing grading on the whole line pole tower based on lightning stroke risks according to the average lightning stroke trip-out rate N. The pole tower with the severe anti-thunder situation can be found before lightning stroke faults occur in the line, modification measures are adopted ahead of time, and the lightning stroke trip-out rate of the power transmission line is reduced.

The invention discloses an automatic matching-based power transmission line fault cause identification method. According to the method, line tripping and log book information is connected into and matched in a lightning locating system, so that the location of a lightning strike fault is judged; and the shielding failure and back striking lightning withstand levels of towers at each stage of a power transmission line are compared with the amplitude of lightning current, so that the nature of the lightning strike fault can be determined. With the method of the invention adopted, the tripping lightning fault of the power transmission line can be automatically identified, a technical basis is provided for the auxiliary decision-making of the post-disaster rapid processing of the lightning strike tripping fault, the application limitations of a method according to which the type of a fault can be diagnosed and the location of the fault can be determined only after line inspection is performed to search a fault point after a lightning strike fault occurs can be eliminated, the repair time and power resuming time of the power transmission line can be greatly shortened, and a large quantity of labor, material and time costs for detecting the fault can be saved.

The invention provides a lightning shielding performance checking method, which divides the span of each line along the entire line into a specified number of sections, and uses a computer to check the relative geometric positions of the ground wires along the line, lightning parameters, topography along the line, and operating voltage of the line in each section. According to the sorting results, the lightning tripping rate calculation method is used to calculate the shielding tripping rate of the line and each span, and according to the relative deviation of the lightning shielding tripping rate of each span to accurately locate the lightning shielding weak point of the line. The present invention checks the lightning shielding performance of the transmission line and takes into account the influence of the terrain condition change of each section in the line span, the relative geometric position change of the ground wire and the phase change of the working voltage of the line, and the evaluation result of the shielding performance of the transmission line is more accurate. Accurate, more authentic and reliable.

The invention discloses a method for distinguishing back flashover faults and lightning shielding failure faults of a power transmission line. The method comprises the following steps of: sampling and recording three-phase transient current on the power transmission line in real time by using a high-speed acquisition device; comparing maximum amplitudes of the three-phase transient current at the same observation point, and judging fault phases; analyzing transient waveforms of fault phase current, and identifying forwarding waves of lightning current; and identifying whether pulses with the polarity opposite to that of the forwarding waves and small amplitudes exist, and determining the pulses as the back flashover faults or the lightning shielding failure faults. The method for identifying fault types by using power frequency voltage in the past is often influenced by load current, the length of a circuit and transition resistance. On the basis of characteristic differences of fault high-frequency transient signals, the method is not influenced by the load current, the length of the circuit and the transition resistance, and has the advantage of simple criterion and easiness in implementation.

The invention relates to a lightening damage early-warning method and system for an electric transmission line. The method includes the following steps that first, weather, satellite, radar and lightening positioning system data are collected, and lightening early-warning parameters at some period in the future are obtained through a comprehensive lightening prediction algorithm; second, according to different lightening overvoltage formation mechanisms, shielding failure and back striking calculation models are selected respectively, calculation is performed through the lightening early-warning parameters and line characteristic parameters, and the lightening trip probability of the electric transmission line is predicted; third, the lightening trip probability of the line is evaluated, the lightening trip probability of each base electric transmission line pole tower is compared with a determined line trip risk early-warning threshold value, and different levels of early-warning signals are obtained. Through the lightening damage early-warning method and system for the electric transmission line, lightening damage to the electric transmission line can be early warned effectively and timely, and technological support is provided for lightening protection and disaster relief of the electric transmission line.

The invention relates to a lightning striking distance based on the shielding failure of the power transmission line of the electro-geometric mode and a determining method thereof, and belongs to the lightningproof technical field of high-voltage transmission lines. The lightning striking distance D sv (I, h, V) provided by the invention is described as follows: D sv (I, h, V) is equal to (-0.004I <2> added with 0.221) h <0.625> <e> <Bv>; wherein, I is lightning current, and the unit thereof is KA; h is the height of a horizontal lead; V is the voltage of the horizontal lead. The determining method of the lightning striking distance includes that the quadratic polynomial of each height of the horizontal lead can be estimated; and the equation of the lightning striking distance D (I, h) related to the height of the horizontal lead can be obtained; when the voltage of the horizontal lead is between minor 1MV and plus 1MV, and when the lightning current is within 200Ka, the correction factor of lightning striking distances under different voltages, kv is equal to e <Bv>, can be achieved by the analog simulation, and finally, the lightning striking distance D sv (I, h, V) can be obtained. The lighting striking distance determined by the method provided by the invention can well meet the physical reality and can reduce the jumping rate of the lightning striking of the power transmission line, thereby guaranteeing the safe operation of power transmission lines.