319results about How to "Guaranteed selectivity" patented technology

A liquid-phase oxidation method of cyclohexane is provided. The oxidation method is characterized in that the method comprises carrying out reaction of molecular oxygen-containing gas and cyclohexane at a mole ratio of (0.1-10):1 in a micro-reactor under 0.8-2.5MPa at 145-200 DEG C for 0.5-30min. The micro-reactor is a micro-channel reactor or a micro-tube reactor. The method ensures safety and enhances heat transfer, and can remarkably improve the oxidizing reaction speed of cyclohexane and the total selectivity of cyclohexanone, cyclohexanol and cyclohexyl hydrogen peroxide.

A hydrocracking process for increasing the output of intermediate fractional oil to maximum features that the hydrorefined heavy petroleum hydrocarbon is contacted first with the beta-zeolite hydrocracking catalyst for cracking the most of raw material and then with the Y-zeolite hydrocracking catalyst for cracking the rest of raw material. Its advantages are high selectivity and low content of olefin in intermediate fractional oil.

The invention relates to a Fe3O4 / CuO / pSiO2 (porous silica) catalyst, a preparation method thereof and application thereof in olefin epoxidation reaction. The preparation method comprises the following processes of: obtaining Fe3O4 microspheres serving as magnetic cores by adopting a co-precipitation method, and modifying the surfaces of the Fe3O4 microspheres by using polyvinyl pyrrolidone (PVP) in order to improve the adsorption effect of the surfaces of the Fe3O4 microspheres on metal cations; coating a CuO nano shell layer on the surfaces of the Fe3O4 microspheres by using copper acetate as a copper source through hydrothermal synthesis; and finally, coating the porous silicon dioxide shell layer by using cetyl trimethyl ammonium bromide (CTAB) as a surfactant and using ethyl orthosilicate as a silicon source, and thus obtaining a composite catalytic material with a magnetic Fe3O4 / CuO / pSiO2 core-shell structure. The catalytic performance of the composite material is researched by respectively using epoxidation reaction of styrene and cyclooctene as probe reaction, and the results prove that the catalytic material has high reaction activity and selectivity, and the catalytic material is easy to separate and recover by introducing the magnetic ores; and the catalytic material has a good circulating effect, still can keep excellent catalytic performance by dozens of times of circulation, and has a great application prospect.

The invention discloses a method for producing succinic acid. The method comprises the following steps of: performing hydrogenation reaction by taking 5 to 90 weight percent of a maleic anhydride gamma-butyrolactone solution as a raw material at the reaction temperature of between 50 and 100 DEG C under the pressure of between 0.2 and 2 MPa in the presence of a hydrogenation catalyst, hydrolyzing a hydrogenation product, crystallizing and separating to obtain succinic acid. The method is can be operated flexibly; reaction conditions are mild and controllable; and products are easy to separate and have good quality.

The invention provides a composite copper-based catalyst, a preparation method and an application thereof in the production of vinyl chloride. The preparation method of the composite copper-based catalyst includes the following steps: soaking acid-treated activated carbon in a solution containing copper salt and an auxiliary agent, and drying and roasting to obtain the composite copper-based catalyst, wherein the auxiliary agent is one or more of ferric chloride, cerium chloride, tin chloride, barium chloride, manganese chloride, zinc chloride, cobalt chloride, lanthanum chloride, nickel chloride, bismuth chloride and potassium chloride; and the mass ratio of the acid-treated activated carbon, the copper salt and the auxiliary agent is 100: 5: 1-100: 10: 5. The catalyst is environment-friendly, low in cost, simple in process and short in production period. The catalyst shows high activity, selectivity and good stability in the reaction of hydrochlorination of acetylene to produce the vinyl chloride, and is expected to be a good substitute for a mercury catalyst.

The invention discloses a Zr-MOF structure based CO selective methanation Ni / ZrO2 catalyst and a preparation method of the Zr-MOF structure based CO selective methanation Ni / ZrO2 catalyst. The main active ingredient of the Ni / ZrO2 catalyst is Ni, the carrier is ZrO2, the specific surface area of the catalyst is 55-98 m<2> / g, the pore diameter is 9.0-16.2 nm, and the Ni capacity is 5-15wt%. The method comprises the following steps: (1) preparing a metal-organic framework Zr-MOF; and (2) preparing the Ni / ZrO2 catalyst. The Ni / ZrO2 catalyst is excellent in CO selective methanation, the content of CO, which is 1 vol%, in a reformed gas is reduced to be lower than 10 ppm under the conditions of wide reaction temperature interval (210-350) and reactant gas space velocity (4,000-20,000 h<-1>), and the selectivity is higher than 50%.

The invention relates to a preparation method of a shell-core structure MOxSiO2, wherein the MOx is one of Mn3O4, Fe2O3, CeO2, Cu2O, or Co3O4. The preparation method comprises following steps: homogenously dispersing 0.01 to 0.1 mol of water-containing inorganic metal salt and 2 to 10 mL of oleic acid into 50 to 100 mL of absolute methanol, then putting the materials in a high-pressure reactor to subject the materials to crystallization reactions for 10 to 48 hours at the temperature of 120 to 240 DEG C, cooling and filtering so as to obtain MOx nano particles, dissolving the MOx nano particles in hexane, adding cetyl trimethyl ammonium bromide solution, subjecting the solution to an ultrasonic treatment, adding sodium hydroxide solution with a concentration of 0.5 M to 2 M, stirring, dropwise adding ethyl orthosilicate, carrying out the reactions at the room temperature for 10 to 24 hours, then subjecting the reaction product to a centrifugation treatment, washing, drying, and burning so as to obtain nano catalyst MOx@SiO2. The preparation method is simple and is easy to be applied to industrial production. The catalyst prepared by the preparation method is applied to the CO oxidation reaction, and has the advantages of low cost, and high activity and stability.

The invention discloses a dual-function catalyst for directly preparing dimethyl ether from synthesis gas and preparation method of the dual-function catalyst, and belongs to the research and preparation field of catalyst. The catalyst is characterized by the dual-function catalyst with a core-shell structure for directly preparing dimethyl ether from synthesis gas and the preparation method of the dual-function catalyst. The method comprises the following steps: using methanol synthesis catalyst as core, and tetraethoxysilane, sodium silicate or silica sol as the silicon source, and using aluminum nitrate as aluminum source, coating a layer of SiO2-Al2O3 shell layer on the surface of the methanol synthesis catalyst so as to obtain the dual-function catalyst with core-shell structure. The dual-function catalyst prepared by the invention is mild in synthesis system condition, and the synthesis system is free from any acid, alkali or organic template, the preparation method of the dual-function catalyst for directly preparing dimethyl ether from synthesis gas is environment-friendly and low in cost.

The invention relates to the field of distribution network relay protection of an electric power system and relates to a voltage acceleration inverse time-delay over-current protection method used for a micro power grid. According to voltage and current information acquired by a protection mounting point, after a short circuit fault occurs and is judged to be a positive directional fault, a method for calculating protection time-delay operation time comprises the step of multiplying an existing inverse time-delay over-current protection setting formula by a voltage accelerated factor to obtain an accelerated operation time, wherein the minimum value of per-unit values of three phase voltages and three line voltages at the protection mounting point is taken as the voltage accelerated factor. The voltage acceleration inverse time-delay over-current protection method used for the micro power grid has the advantages that the time for eliminating the short circuit fault at line exit is very short, the delay-free operation is achieved, the faults at other points on the line and various faults also can be quickly processed, and the demand on rapidity is met.

The invention relates to an intelligent protective loop framework system and an intelligent protecting method of a power supply looped network. The system uses transformers in various sections of buses, various looped network cables and various feed line loops in the power supply looped network as independent protective objects, all protective objects form a protective region of the protective objects through wire inlet and outlet breakers directly connected with the protective objects; information resource sharing is achieved through networking related current sensors with related protectivedevices, the protective devices can extract output information of any one sensor on the network, if the protective objects have short circuit faults, and all various related protective devices can rapidly extract current information at two ends of a fault region for comprehensive judgment so as to rapidly cut off the circuit breakers at two ends of the fault region by using short delay; and if the circuit breaker of the fault region rejects the separating brake because of the fault, the system enlarges the protection to a standby region. The system is suitable for massive popularization and application because the protection does not need setting calculation, and has important production practical significance.

The invention relates to a method for removing carbon dioxide in natural gas by utilizing a novel high specific surface active carbon material. The method comprises the following steps of: washing the active carbon material in a reactor by utilizing an inert gas; heating and removing impurities; vacuumizing, and introducing the natural gas to the reactor filled with the active carbon material; adsorbing the carbon dioxide and discharging the carbon dioxide-removed natural gas; then reducing the pressure to a normal pressure, and then desorbing a nitrogen gas through the active carbon material at the room temperature to obtain the carbon dioxide-removed natural gas. By utilizing the adsorption method of the active carbon material, the content of the carbon dioxide in the natural gas can be reduced to 0.05 volume%, the volume of the treated natural gas is more than 1,000 times that of the active carbon material of the method, the selectivity is still kept through adsorption and desorption cycles, therefore, the active carbon material of the method can satisfy the actual use requirement and has favorable application prospect.

The invention specifically discloses a system and method for high-efficiency extraction of vanadium from vanadium slag through chlorination, belonging to the fields of chemical engineering and metallurgy. By means of heat exchange between chlorination gas and chlorination flue gas, the chlorination gas is preheated; a proper amount of air is added to allow a part of coke powder to combust, thus providing a balanced supply of heat during the process of chlorination; by means of high-temperature fluidization oxidation of chlorinated slag, the chlorinated slag is treated in a comprehensive manner, and the chlorine gas is recycled; furthermore, by means of vapor-phase hydrolysis of the chlorination product vanadium oxytrichloride, a powdered vanadium pentoxide product and a hydrochloric acid byproduct are obtained; so the efficiency of chlorination is improved, the consumption of chlorine gas is reduced, the harm of the chlorinated slag is eliminated, and the problem of ammonia-nitrogen pollution caused by conventional ammonium salt precipitation is prevented. The system and method provided by the invention are applicable to extraction of vanadium from vanadium slag containing 10 to 28 wt% of V2O5 through chlorination and have the advantages of high efficiency, low energy consumption, no pollution, good economic performance, etc.

The invention provides a catalyst for preparing formic acid from carbon dioxide by electroreduction and a preparation method of the catalyst, and belongs to the field of electro-catalysis. The catalyst is a chalcogen-doped metal electrocatalyst, chalcogen contains at least one of sulfur, selenium and tellurium, and metal contains at least one of indium, stannum, lead and bismuth. The preparation method comprises following steps: 1), an elementary substance of chalcogen or a compound of chalcogen is dissolved in N,N-dimethyl formamide with metal salts, a carbon material is placed, and a mixtureis transferred into a high-pressure kettle and subjected to solvent heat treatment; 2), after the solvent heat treatment, the carbon material is taken out, washed by deionized water and dried, a carbon material supported chalcogen-doped metal oxide precursor is obtained and then subjected to electroreduction, and the carbon material supported chalcogen-doped metal electrocatalyst is obtained. When applied to the reaction of preparing formic acid from carbon dioxide by electroreduction, the catalyst is high in reactivity, high in selectivity and stable in catalytic performance and maintains high formic acid selectivity in a wide current range.

Provided are a system and method for highly effective chlorination and vanadium extraction from vanadium slag. By means of heat exchange between a chlorination gas and a chlorination flue gas, a chlorination gas is preheated and an appropriate amount of air is added, which causes coke powder to partially combust, thus providing a balanced supply of heat during the process of chlorination; also, by means of high-temperature fluidization oxidation of the chlorinated slag, the chlorinated slag is used in a comprehensive manner, and the chlorine gas is recycled; further, by means of vapor-phase hydrolysis of the vanadium oxytrichloride product of chlorination, a powdered divanadium pentoxide product is obtained; the reaction efficiency of chlorination is improved, the consumption of chlorine gas is reduced, the harm of chlorinated slag is eliminated, and the pollution problem caused by conventional ammonium salt precipitation is prevented.

The present invention discloses a method for preparing ethylene alcohol by a catalyzing and hydration method, which comprises the following steps: the ethylene alcohol solution EC / EG / H2O / CAT includingDioxo carbonate and even catalyzer absorbs EO gas; the most part of EC / EG / H2O / CAT / EO solution reacts with CO2 to obtain EC / EG / H2O / CAT solution for the repeated use; the EC / EG / H2O / CAT / EO solution absorbs the residual solution and takes hydrolyzing reaction with water as well as taking hydration reaction with water to obtain EG / H2O / CAT / DEG solution; and then ethylene alcohol is obtained by the distilling operation. The condition for the hydration of ethylene alcohol and the hydrolyzing of Dioxo carbonate is: the molar ratio between the total molar of water and the total molar of ethylene alcohol and Dioxo carbonate is 1-5; the reaction temperature is 60-200 Celsius system; the pressure is 0.10-3.0MPa; and the reaction time is 5-240 minutes.

The present invention discloses a low energy consumption hydrocracking method for producing a high-quality chemical industry raw material. According to the method, a raw material oil and hydrogen gas are subjected to heat exchange two times, and then sequentially pass through a hydrorefining reaction zone and a hydrocracking reaction zone, wherein the hydrocracking reaction zone comprises at least two hydrocracking catalysts, the upstream is filled with a catalyst I, the downstream is filled with a catalyst II, the catalyst I contains 30-70 wt% of a modified Y molecular sieve, the catalyst II contains 15-50 wt% of the modified Y molecular sieve, and the modified Y molecular sieve content in the catalyst I is 10-30% higher than the modified Y molecular sieve content in the catalyst II. According to the method of the present invention, the high temperature high pressure countercurrent heat transfer technology and the hydrocracking catalyst grading technology are organically combined, and the hydrocracking reaction heat is comprehensively utilized, such that the characteristics of the two different types of the hydrocracking catalysts are completely provided, and the catalyst selectivity is maintained while the target product quality is improved, and the project investment and the operating energy consumption are reduced.

The invention discloses a bus protection algorithm for realizing GIS accurate fault removing and automatic power supply recovery. The bus protection algorithm comprises the steps that bus wide-range differential current, bus small-range differential current and interval differential current are calculated respectively; faults outside a bus area and faults inside the bus area are distinguished according to actuation of a high-difference-ratio element; when the high-difference-ratio element actuates, the segment of bus on which the faults occur is determined by actuation of a low-difference-ratio element; a fault interval is determined by actuation of an interval ratio differential element; and the type of the faults is judged and the faults are responded according to the actuation situation of the high-difference-ratio element, the low-difference-ratio element and the interval ratio differential element. The beneficial effects of the bus protection algorithm are that the fault position can be accurately judged and the faults can be rapidly removed and isolated so that a situation that all connecting elements are tripped by bus protection when single interval internal faults occur can be prevented, selectivity of bus protection actuation can be guaranteed, accident scope can be reduced and system operation stability can be enhanced.

The invention discloses a preparation method of a palladium-carbon catalyst for synthesizing meropenem. The preparation method comprises the following steps: (1) putting wood charcoal into a boiling alkali compound water solution, carrying out backflow treatment, washing by virtue of pure water, and drying to obtain an active carbon carrier; (2) preparing an active ingredient solution, and regulating the pH value of the active ingredient solution; (3) pulping the active carbon carrier, and stabilizing the active carbon carrier at a stirring condition, so as to obtain active carbon slurry; (4) adding the active ingredient solution into the active carbon slurry after the pH value of the active ingredient solution is regulated, and stirring to obtain a catalyst precursor; and (5) aging the catalyst precursor, and reducing the catalyst precursor by virtue of a reducing agent, so as to obtain a catalyst finished product. According the preparation method, a low-content alkali compound is utilized for processing the carrier so as to obtain a proper carrier with a reasonable surface chemical structure, so that the consumption of a reagent is reduced; chelated palladium ions of a certain size are prepared by regulating the pH value of the active component solution, so that purposes of controlling the activity and selectivity of the catalyst are realized; the preparation method has no special control point, is simple in process and is beneficial to the industrial large scale production.

The invention relates to a rock core shape-preserving three-dimensional reconstruction method. The method comprises the steps that holographic image information of the contour of a rock core is obtained through multi-angle shooting of a calibrated measurement camera, and then a high-density point cloud on the surface of the rock core is obtained by means of scanning analysis of a high-performance computer on images according to the dense curve modeling technology; gridding and automatic filling of the surface of the rock core are completed through effective determination of the point cloud, and therefore the three-dimensional reconstruction of the rock core is completed. Compared with a traditional rock core characterization method, a large amount of three-dimensional information of the rock core with the original shape can be obtained instantly, no rock core shape selectivity exists, no special handling is needed, the original shape of the rock core can be well kept, the cost is low, operation is convenient and fast, the degree of automation is high, on-site quantitative analysis can be carried out on a coring site, the defects of existing methods are effectively overcome, and the rock core shape-preserving three-dimensional reconstruction method is efficient, fast, low in cost, accurate and reliable.

The invention relates to a technical method for preparing aromatic hydrocarbon through methanol aromatization. The technical method is characterized by comprising the steps: firstly, reacting methanol in a fixed-bed reactor filled with a methanol hydrocarbonylation reaction catalyst and an olefin aromatization catalyst, enabling the reacted product to enter a reactor filled with a non-aromatic cracking agent, reacting, separating the product to obtain dry gas, C<3+> non-aromatic hydrocarbon and aromatic hydrocarbon, wherein the dry gas and the aromatic hydrocarbon are output from the system as products, the C<3+> non-aromatic hydrocarbon is dehydrogenated after entering a dehydrogenation reactor, the dehydrogenated C<3+> non-aromatic hydrocarbon returns a methanol hydrocarbonylation reactor for continuing reaction. Through the technique, the methanol conversion, olefin aromatization, non-aromatic cracking and alkane dehydrogenation technology are combined, so that no only can the yield and selectivity of aromatic hydrocarbon be improved, but also the separation difficulty of aromatic hydrocarbon can be lowered. Through the technique, the total yield of the aromatic hydrocarbon (based on mass of methanol) can achieve 30-34%.

The invention belongs to the field of a metal ion sensing technology, in particular to an electropolymerizable fluorescent sensing material and application of the electropolymerizable fluorescent sensing material on fluorescent or electropolymerizable detection of metal ions. According to the electropolymerizable fluorescent sensing material, 2, 7-fluorene and 2, 2'-dipyridyl (or 1, 10-phenanthroline) are served as a main chain, and a side chain is connected with a carbazole group through an alkyl group. A rigid main chain structure of a compound provided by the invention guarantees the fluorescent sensing material to have high fluorescent efficiency, but a side chain of strong metal identification unit guarantees selectivity of a detection material. In addition, a micropore structure of a film prepared by electropolymerization can effectively guarantee the metal ions to quickly diffuse in the film and improve flexibility of film detection. According to the fluorescent sensing material provided by the invention, raw materials with cheap prices are easily obtained, and a synthesis process is relatively simple, so that the electropolymerizable fluorescent sensing material is a metal ion fluorescent / electrochemical sensing film material with high potential.

The invention discloses an adaptive current protection method for a power distribution network including a high-permeability distributed power supply. The method comprises the following steps: performing Thevenin equivalence on the distributed power supply; acquiring current and voltage information of a distributed power supply grid connection point; calculating an equivalent impedance of the distributed power supply in real time through fault current and voltage components of the distributed power supply grid connection point in the case of a fault; and putting the equivalent impedance into a setting valve calculation formula to calculate a protected setting value in real time. Through adoption of the adaptive current protection method, influences on current protection caused by access of the distributed power supply to the power distribution network can be effectively eliminated, and the situation that a protection range of the current protection changes along with the change of an access capacity of the distributed power supply is avoided. The adaptive current protection method has important significance in ensuring correct actions of the current protection under the situation of the power distribution network to which the high-permeability distributed power supply accesses.

The invention relates to a hydrocracking method for reforming material yield increase. Raw oil and hydrogen gas are mixed and then the mixture is sequentially subjected to hydrorefining reaction and hydrocracking reaction, reaction effluent is cooled and separated, and then, the obtained light diesel fractions with the volume percentage being 10 to 100 percent and the distillation range being 220 to 320 DEG C return to a hydrocracking reaction vessel for continuous reaction. Because the arene content and cyclane content of the part of fractions are high, the fractions are proper fractions for high-quality heavy naphtha yield increase, and the yield of aviation fuel and the cetane number of the diesel fractions can also be improved through recycling the fractions. When the method provided by the invention is adopted, the recycled light diesel fractions enter the hydrocracking reaction vessel instead of a raw material tank and do not pass through a hydrorefining reaction vessel, so few arene and cyclane parts take hydrosaturation reaction, the potential arene of the heavy naphtha is favorably improved, and the hydrogen consumption is favorably reduced.

The invention relates to a wave correlation based current protection method for power collecting lines in a wind farm. The method comprises the following steps: firstly, three-phase current in protective mounting position of each power collecting line in the wind farm is collected; filtering is performed, and fault component current of each phase is extracted by programming; correlation coefficients of the phases between the power collecting lines is calculated according to the fault component current, and the correlation coefficients are traversed pairwise; if the correlation coefficient of one phase belongs to (0, 1], the phase of the two power collecting lines has no fault, and the two power collecting lines are written as line i and line j; if the correlation coefficient of the one phase does not belong to (0,1], the phase of one and only one of the two power collecting lines has a fault, and the two power collecting lines are written as line u and line v; at the moment, when the correlation coefficient of the phase between the line u and the line j belongs to (0,1], the phase of the power collecting line u has no fault, while the phase of the power collecting line v has a fault; when the correlation coefficient of the phase between the line u and the line j does not belong to (0,1], the phase of the power collecting line u has a fault, while the phase of the power collecting line v has no fault.

The invention belongs to the technical field of power system relay protection and especially relates to a T line protection scheme fit for distributed electrical connection. The T line protection scheme is characterized in that a distance protection starting element acts after the fault occurs; if the inaction condition for main criterion is not met, the trip protection is performed through zero sequence voltage amplitude difference, and if not, the distance section-II protection can be used for judging the fault direction; if section-II measuring elements at three ends are judged as positive direction fault and the acting condition of auxiliary criterion section-I protection is met, the trip protection is performed through the distance section-I protection at three ends; if the acting condition of auxiliary criterion section-I protection is not met, the section-II protection at three ends is delayed and then is tripped out; if two section-II measuring elements judge as positive direction fault and one section-II measuring element judges as negative direction fault, a locking signal is sent to section-I protection at the opposite end by the negative direction fault end and the section-I protection at three ends all shall not trip out. According to the T line protection scheme fit for distributed electrical connection, the active criterion and the auxiliary criterion are organically matched and formed into a comprehensive criterion, so that the selectivity, sensitivity and reliability of the T line protection can be ensured.

The invention relates to a catalyst for producing furfuryl alcohol, a preparation method thereof, and a furfuryl alcohol production method. The catalyst comprises a main active component, an assistantand a passivated carrier, wherein the main active component is Cu, the assistant is one or more of an alkali metal, an alkali earth metal and a rare earth metal oxide, and the passivated carrier is asilicon oxide-containing inorganic carrier. The catalyst is characterized in that the passivation treatment of the carrier is one or more of heat treatment, silanization and etherification. The catalyst is prepared by an ammonia evaporation induced deposition precipitation process, so the preparation method has the advantages of simplicity, convenience, low requirements for devices needed by rawmaterial storage and catalyst preparation, and easiness in large-scale amplified amplification. The catalyst has the advantages of high single conversion of furfural, high furfuryl alcohol selectivity, long life and good industrial application prospect when applied to furfural hydrogenation.

The invention relates to a method for preparing methyl chlorosilane from organosilicon high-boiling products. The method comprises the steps as follows: the whole composition of the high-boiling products which are the byproduct in the production process of dimethyl dichlorosilane as the organosilicon monomer is adopted as the raw material and reacts with hydrogen chloride in the presence of N,N-dimethylanlilne and tri-n-butylamine as a catalyst in a cracking kettle with a fractionating tower to obtain a mixed monomer mainly containing dimethyl dichlorosilane, trimethylchlorosilane, methyldichlorosilane and methyltrichlorosilane; and the mixed monomer is collected via the overhead condenser of the fractionating tower. The method can improve the conversion of the high-boiling products. The conversion is higher than 90%, the dimethyl dichlorosilane allows a selectivity of higher than 50%, and the selectivety of trimethylchlorosilane reaches 10%. The organosilicon monomer can be prepared at low cost.

The invention discloses a protection method for a multilevel direct current distribution feeder line. The protection method is implemented according to the following steps specifically: step one, collecting the current ix(k) at the outlet of each level of direct current bus of the multilevel direct current distribution feeder line, and calculating a current increment measured value delta ix(k), wherein x is A, B, ..., M level, and k is the sampling number of the current at the outlet of each level of direct current bus; step two, judging the fault section of the multilevel direct current distribution feeder line; and step three, restarting a current converter. The protection method for the multilevel direct current distribution feeder line disclosed by the invention can be matched with the protection of the current converter, the fault section of the direct current feeder line can be identified correctly, a cutting fault is protected by a corresponding feeder line, and adjacent feeder lines are protected from operating falsely, so that the action selectivity of a direct current circuit breaker is guaranteed.