46results about How to "Avoid large-scale power outages" patented technology

The invention provides an implementing method of an integrated power grid dispatching operation intelligent mistaken-early-warning preventing system. The implementing method comprises the following steps that various information and computing resources required by an operation ticket system in an EMS system of a dispatching center are packaged into standardized service; the operation ticket system is integrated a DMIS system of the dispatching center, and a graphic platform is built according to the CIM and SVG standard; an intelligent ticket-making expert rule base based on an operation model is built, and a safe mistake preventing system based on operation term analysis and comprehensive instruction analysis is built. The implementing method has the advantages of having little influence on the EMS system, being beneficial for popularization and the like, and can improve billing efficiency and circulation speed of dispatching operation tickets. During equipment maintaining peaks in spring and autumn, equipment operation safety is guaranteed, rapidness of equipment operation is guaranteed, work efficiency and the production and management level of the power grid are improved, prevention of large-area power outage accidents is facilitated, and safe production of an electric power company is guaranteed.

The invention relates to a power system weak link identification method based on risk evaluation and belongs to the field of power system analysis. The method includes acquiring fault probability of elements of a power system, a future load curve of the power system, states of the elements and load of nodes of the power system; utilizing a minimum load shedding loss optimization model to judge the failure state of the power system and determining the optimum load shedding quantity of each node under each element sampling state; finishing calculation of risk indicators of the power system through repeated sampling and power system failure state judgment; conducting statistics on the weak link characteristic quantity corresponding to faults of generators and an electric transmission and transformation device, calculating five element weakness recognition indicators of the elements according to the risk indicators and the weak link characteristic quantity and finally sorting the recognition indicator values to recognize the weak link of a generator set and the electric transmission and transformation device. By means of the method, the weak link of the power system is improved, large-area power failure of the power system is prevented, and operation safety of the power system is improved.

A self-adaptive intelligent coordination protection and control system for power grids based on WANs (Wide Area Network) and multiple agents has the design scheme that according to the characters of hierarchical structure and geograhical distribution of a power system, a developing and modeling method of the software Agent is used to establish a divisional and hierarchical system. The system realizes coordination of protection actions by the capacity of a multi-agent system for solving distributed on-line questions. Through the plan to protect setting tasks, each agent is responsible for a specific task, and thus, the multi-agent system can establish knowledge libraries of all agents rightly and obtain high search efficiency. Each agent improves performance per se by exchanging information and learning from others, and then improves the capacity of the whole self-adaptive coordination protection system for solving questions. Because of the loose coupling relationship among the agents, the whole system has a more flexible structure and has real-time response to environmental changes.

The invention belongs to the technical field of power transmission line state monitoring, and discloses an online monitoring system for galloping of an overhead power transmission line. The online monitoring system is characterized in that the online monitoring system for the line of each span consists of a plurality of monitoring substations, two monitoring master stations and a background monitoring upper computer, wherein the monitoring substations are arranged on the transmission line; the two monitoring master stations are arranged on towers respectively; the background monitoring upper computer is arranged in a monitoring center; the two master stations and the plurality of substations monitor the galloping state of the line of each span; the substations accurately position the galloping of the line by utilizing acceleration sensors, and upload positioning data to the master stations through short-range radio frequency; each master station receives galloping monitoring data from four nearby substations, and uploads the monitoring data and environmental meteorological data to the background monitoring upper computer through a general packet radio service (GPRS); and when each master station synchronizes a clock through a global positioning system (GPS) module, the synchronism of the uploaded data is ensured. The online monitoring system has a small volume, low influence on mechanical properties of the line, high dynamic performance and high data monitoring accuracy, is low in cost, and can work round the clock.

The invention discloses a power grid operation state judgment method and system based on fuzzy clustering and RS-KNN model. The method comprises the following steps: Step 1: selecting a characteristicvariable for discriminating the operation state of the power grid; and Step 2: using a fuzzy clustering algorithm to divide the health state of the power grid operation into four types according to the health degree, which are respectively health, sub-health, general illness and serious illness. Before clustering, in order to eliminate the influence of the data dimension, a normalization method needs to be adopted to process the characteristic variable data of the power grid. Step 3: taking the characteristic variables obtained in the step 1 as input variables of a training set, taking data corresponding to the classified power grid operation states obtained in the step 2 is used as an input variable of a training set, and setting labels corresponding to the four power grid operation states, namely, the health state, the sub-health state, the general illness state and the serious illness state, output by the training set to be 1, 2, 3 and 4 respectively. Step 4: using the obtained four kinds of power grid operation state data to train RS-KNN model.

The invention provides a direct current micro-grid system supplying power in a looped network mode. The direct current micro-grid system supplying the power in the looped network mode comprises looped-network-shaped direct current buses with different voltage levels, a mixed current circuit breaker connected between bus sections, a photovoltaic power generation system, an energy storage power source, an internal-combustion engine, a convertor, direct current loads and alternating current loads, wherein the photovoltaic power generation system, the energy storage power source, the internal-combustion engine, the convertor, the direct current loads and the alternating current loads are connected to the direct current buses. The energy storage power source and the photovoltaic power generation system are connected with the looped-network-shaped direct current buses with the different voltage levels through the convertor. The mixed current circuit breaker acts when a fault point occurs to a certain section line of the direct current buses, and a solid-state switch of the mixed current circuit breaker breaks the fault point. The internal-combustion engine is connected with the looped-network-shaped direct current buses with the different voltage levels through the convertor, and provides backup power for the direct current loads and the alternating current loads of the direct current micro-grid system when the mixed current circuit breaker acts. According to the direct current micro-grid system supplying power in the looped network mode, when faults occur to a certain part of lines, the mixed current circuit breaker acts timely to isolate the fault part, and a large-area power outage accident is avoided.

The invention relates to a grid fault positioning method based on wide area voltage. The method comprises the steps of firstly extracting fault voltage components of all nodes, then dividing the entire system into a fault area, areas influenced by the fault and areas basically uninfluenced by the fault according to the magnitude of the fault voltage, respectively taking different precaution and alarming measures to the areas according to the degrees of the influence of the fault, preliminarily defining a fault range, performing fault positioning to the fault area by adopting a fault analysis method based on the wide area voltage and finally recording and feeding back fault data for making a preparation for the fault positioning at the next time. The grid fault positioning method based on the wide area voltage has the advantages that the grid fault can be rapidly positioned by adopting the voltage data only and the problem of inconvenience in the processing due to the large data size of a wide area system is solved; the fault can be accurately positioned to a certain section of a line by using the method, favorable conditions are created for troubleshooting the grid fault in time and preventing overload and other problems from causing intertripping, and the accident of large-area power outage is effectively avoided.

The invention discloses a power transmission line mountain fire identification method based on temperature distribution. The power transmission line mountain fire identification method based on temperature distribution includes the following steps: 1) mountain fire monitoring image preprocessing and color mode conversion; 2) flame primary determination based on color characteristics; 3) mountain fire characteristic extraction based on color characteristic difference; and 4) mountain fire identification based on temperature distribution. The power transmission line mountain fire identification method based on temperature distribution can effectively identify the mountain fire areas in the images and can effectively exclude the interference factors, such as sunlight and car lights by considering the nonuniformity of temperature distribution in the flame areas. The power transmission line mountain fire identification method based on temperature distribution has the advantages of being clear in thinking, being convenient for operation, and being high in practicality, and can be widely applied to the field of power transmission line mountain fire monitoring and alarm.

The invention relates to a power transmission line phase-to-phase distance protection section III protection method. The method comprises the steps that a fault phase-to-phase voltage, a fault phase-to-phase current and a fault phase-to-phase negative-sequence current at a power transmission line protective installation position are measured firstly, a phase-to-phase arc voltage at a phase-to-phase short-circuit fault point of the power transmission line is calculated, and then the amplitude of the phase-to-phase arc voltage and a rated voltage amplitude of the power transmission line are utilized to form a power transmission line phase-to-phase short-circuit fault relay protection criterion. According to the power transmission line phase-to-phase distance protection section III protection method, lumped parameters are adopted for modeling, the algorithm principle is simple, programs are implemented easily, the calculation amount is small, and protective action is high in speed. By means of the power transmission line phase-to-phase distance protection section III protection method, the power transmission line phase-to-phase short-circuit fault relay protection criterion is formed by utilizing the amplitude characteristics of the phase-to-phase arc voltage, motion performance is not affected by transition resistance and load current, large-area power outage of a power grid caused by great shift of power grid tidal current due to phase-to-phase distance protection III protection false operations under the condition of overload of the power transmission line is effectively prevented, and operation safety and stability of the power grid are reinforced.

The invention discloses a fiber channel-based hot standby line power-side control standby power supply switching method. A C station is applied to a 110kV inner bridge primary main line of a 110kV substation, or a 110kV single bus line section primary main line of the 110kV substation. The problems of substation capacitive over high reactive power and power grid reactive power inverse transmissioncan be solved, the voltage level of the substation is improved, local power grid voltage can be prevented from being over high, and the overall operation level of the power grid is enhanced. The equipment loss and the insulation aging are reduced, the operating efficiency of the substation main equipment is improved, the substation power factor is improved, and the economical operation of the power grid is improved. The occurrence of large-scale power outage accidents when the main supply line is permanently faulty is effectively avoided, self-healing of the power grid is realized, and the power supply reliability is improved. The method disclosed in the invention can be used as a technical guarantee for the special operation mode of the power grid, thereby greatly improving the safety risk management and control under the special operation mode and promoting the safe and stable operation of the power grid.

The invention relates to a mid-long term voltage stability evaluation method for receiving-end power grids. The method comprises the steps of building a full process dynamic simulation program model, of considering slow dynamic component movement, for partition running receiving-end power grids; obtaining voltage weak nodes corresponding to the partition running receiving-end power grids; obtaining a PV curve of the voltage weak nodes before and after the slow dynamic component movement in the mode of slow growth of a load; determining a power limit point of the PV curve of the voltage weak nodes after the slow dynamic component movement; obtaining a state transition curve of the power limit point and determining an intersection point of the state transition curve and the PV curve of the voltage weak nodes before the slow dynamic component movement; and evaluating the mid-long term voltage stability of the receiving-end power grids according to data corresponding to the intersection point of the state transition curve and the PV curve of the voltage weak nodes before the slow dynamic component movement. By the method provided by the invention, the voltage stability of the receiving-end power grids can be effectively monitored; and the safe and stable operation level of an interconnected power grid is improved.

The invention discloses a dynamic control method for a state machine of relay protection equipment of an intelligent substation. The method comprises the steps of defining a state set of each type ofrelay protection equipment of the intelligent substation; defining a state transition diagram control direction of the relay protection equipment to form a state transition diagram of each type of relay protection equipment; defining a state transition trigger condition of each type of relay protection equipment of the intelligent substation; dynamically matching a current state of each relay protection equipment of the intelligent substation; completing dynamic detection of the state transition trigger condition of the relay protection equipment; and outputting a state result of the relay protection equipment, and achieving state identification of the relay protection equipment of the intelligent substation. According to the method provided by the invention, the state of the relay protection equipment of the intelligent substation can be dynamically identified, and a foundation is laid for achieving non-correspondence monitoring and maintenance and safety verification application of running states of primary and secondary equipment of the intelligent substation.

The invention provides an intelligent electric carrier classification locking device, which is characterized by comprising an electric wire coupler connected with a low-voltage electric wire, wherein an electric wire signal modulator-demodulator is connected with the electric wire coupler through a signal receiver and a signal emitter; and a digital signal interface is connected with the electric wire signal modulator-demodulator through a single chip microprocessor. With the adoption of the intelligent electric carrier classification locking device provided by the invention, the defects in the prior art can be overcome; a fault circuit and a non-fault circuit can be automatically judged; and a power supply of the fault circuit can be automatically switched off, and the fault circuit is locked, so that the occurrence of the large-area switched-off circuit caused by error operation of staff and the hidden dangers of directly causing personal security due to illegal operation can be avoided. Furthermore, the intelligent electric carrier classification locking device has no need of wiring; the cost is lowered; and the convenience in use is realized.

The invention relates to a power transmission line overload false operation prevention phase-to-phase distance backup protection method. The method comprises the steps that a fault phase-to-phase voltage, a fault phase-to-phase current and a fault phase-to-phase negative-sequence current at a power transmission line protective installation position are measured firstly, voltage drop along a power transmission line is calculated, the voltage drop along the power transmission line is subtracted from the fault phase-to-phase voltage at the power transmission line protective installation position to obtain voltage drop of phase-to-phase arc light at a phase-to-phase short-circuit fault point of the power transmission line, and then the voltage drop of the phase-to-phase arc light and a rated phase-to-phase voltage of the power transmission line are utilized to form a power transmission line phase-to-phase distance backup protection criterion. By means of the power transmission line overload false operation prevention phase-to-phase distance backup protection method, the power transmission line phase-to-phase distance backup protection criterion is formed by utilizing the amplitude characteristics of the voltage drop of the phase-to-phase arc light, motion performance is not affected by transition resistance, load current and operating modes of an electric power system, large-area power outage of a power grid caused by great shift of power grid tidal current due to phase-to-phase distance backup protection false operations under the condition of overload of the power transmission line is effectively prevented, and operation safety and stability of the power grid are reinforced.

The invention discloses a cable terminal grounding wire, which relates to the technical field of high-voltage cable branching cabinet maintenance tools and is structurally characterized in that a through hole is arranged in the middle of a grounding wire contact plate, a hollow contact is sleeved in the through hole in a penetrating manner, internal threads are arranged in the hollow contact, one end is in threaded connection with a screw, and a sleeve further sleeves the hollow contact. One end of the sleeve is connected with an external thread arranged on a protrusion of the ground wire contact plate, an inner bayonet is arranged in the middle of one end of the insulating rod, the inner bayonet is matched with a screw of the hollow contact, and the ground wire is connected with a ground wire clamp. The cable terminal grounding wire has the beneficial effects that when the novel device is used in actual work, rapid, safe and reliable grounding of a cable terminal grounding wire and a cable terminal can be realized; according to the cable terminal grounding wire, the original hanging checking mode of large-area power failure for hanging the grounding wire can be changed in special occasions, so that the occurrence of large-area power failure accidents is avoided, the power supply reliability is guaranteed, and invisible safety benefits are created for enterprises and society.

The invention provides a method for preventing a damping wire of a ground wire of a transmission line from breaking. According to the method provided by the invention, by utilizing a protecting device (3) consisting of two rectangular protective blocks which are arranged in a bilateral symmetry mode, corrosion destruction of various corrosive gases, ultraviolet rays, moral integrity rainwater and water steam above a stream of the outside on the ground wire (1) of the transmission line and the damping wire (3) are isolated, thus improving the corrosion resistance and breaking resistance of the damping wire of the ground wire of the transmission line, achieving the purpose of durability of the damping wire of the ground wire of the transmission line, and improving the corrosion resistance of the damping wire of the ground wire of the transmission line. With the adoption of the method, the corrosion resistance to metals of the damping wire of the ground wire of the transmission line is obvious, accidents of power failure in a large area due to grounding short circuit faults of the transmission line due to breaking of the damping wire of the ground wire are prevented, the grid power transmission and distribution safety production level is increased, and the method is suitable for protecting the damping wire of the ground wire of the transmission line.

The invention discloses a grid circuit overload maloperation-preventing relay protection method based on wide-area information. According to the method, an existing wide-area measuring system of a grid is used for synchronously measuring the phasor quantity of the voltages and the phasor quantity of the currents of all transformer substations at first; if a grid single circuit trips, a wide-area backup protection system sequentially calculates the corrected impedance, the corrected admittance and the compensation voltage; voltages of all nodes of the grid of which the circuit has not tripped and the compensation voltage are superposed to obtain the voltage phasor quantities of all transformer substations of the grid which tripped; the currents flowing through all circuits in the grid are calculated and combined with circuit currents measured by the existing wide-area measuring system to form overload maloperation-preventing protection criteria. According to the grid circuit overload maloperation-preventing relay protection method based on the wide-area information, the protection action speed is high, the circuits can be reliably shut before ciruit overload protection maloperation occurs, other circuits are protected against overload and mistaken cutting, wherein the overload is caused by transferring of the currents after the grid single circuit tripped, and the large-area power failure of the grid is effectively prevented.

The invention discloses a combined standby power switch-in method based on a hot standby line. The method is applied to the 110kV inner bridge primary main line of an 110kV substation or the110kV single bus section primary main line of the 110kV substation. The method solves the problem of substation over-high capacitive reactive power and grid reactive power backflow, improves the substation voltage level, avoids over-high local grid voltage, improves the overall operation level of the grid, reduces equipment loss and insulation aging, improves the operating efficiency of the substation mainequipment, increases a substation power factor, improves the economical operation of the grid, avoids the large-scale power outage accidents when the main supply line is permanently faulty, realizes self-healing of the grid, and improves the reliability of power supply. The method can be used as a technical guarantee for the special operation mode of the grid, greatly improves the safety risk management and control under the special operation mode, and promotes the safe and stable operation of the grid.

The invention belongs to the field of energy conversion devices, in particular to an electric energy multiplication power station which comprises an initial starting motor (1), an electromagnetic induction electromotor (3) and a ceramic generator (4); the output shaft of the initial starting motor (1) is adapted to the input shaft of the electromagnetic induction electromotor (3) through a clutch (2); the output shaft of the electromagnetic induction electromotor (3) is fixedly adapted to the input shaft of the ceramic generator (4); and the power output end of the ceramic generator (4) is connected with the power input end of the electromagnetic induction electromotor (3). The electric energy multiplication power station has simple structure, low cost, high safety factors and ideal energy conversion efficiency.

The invention discloses an optical fiber channel hot standby line standby power supply input method based on main transformer control. The method is applied to the following lines: a primary main wireof a 110kV inner bridge of a 110kV substation; and a subsection primary main wire of a 110kV single-bus of the 110kV substation. According to the invention, the problems of too high capacitive reactive power and power grid reactive power transfer of the transformer substation are solved, the voltage level of the transformer substation is improved, local power grid voltage is prevented from beingtoo high, and the overall operation level of the power grid is improved. Equipment loss and insulation aging are reduced, the operation efficiency of main equipment of the transformer substation is improved, the power factor of the transformer substation is improved, and the economical efficiency of power grid operation is improved. Large-area power failure accidents during permanent faults of a main supply line are effectively avoided, the self-healing of the power grid is achieved, and the power supply reliability is improved. The method can be used for providing the technical guarantee fora special operation mode of the power grid, greatly improves safety risk management and control under the special operation mode, and promotes safe and stable operation of the power grid.

The invention discloses a hot standby line combined standby power input method based on a power supply side fiber channel, and the method is applied to following primary wiring including the 110kV inner bridge primary main wiring of a 110kV substation and the 110kV single bus section primary main wiring of the 110kV substation. According to the invention, the problems of the over high capacitive reactive power of a substation and grid reactive reversal are solved, the voltage level of the substation is improved, the over high voltage of a local grid is prevented, and the overall operation level of a power grid is improved. The equipment loss and insulation aging are reduced, the operating efficiency of the substation main equipment is improved, the power factor of the substation is improved, and the economic efficiency of the power grid operation is improved. The occurrence of a large-scale power outage accident when a main supply line is permanently faulty is effectively avoided, theself-recovery of the power grid is achieved, and the reliability of power supply is improved. The method can be taken as a technical guarantee for the special operation mode of the power grid, the safety risk management and control under the special operation mode is greatly improved, and the safe and stable operation of the power grid is promoted.

The invention belongs to the technical field of power transmission line state monitoring, and discloses an online monitoring system for galloping of an overhead power transmission line. The online monitoring system is characterized in that the online monitoring system for the line of each span consists of a plurality of monitoring substations, two monitoring master stations and a background monitoring upper computer, wherein the monitoring substations are arranged on the transmission line; the two monitoring master stations are arranged on towers respectively; the background monitoring upper computer is arranged in a monitoring center; the two master stations and the plurality of substations monitor the galloping state of the line of each span; the substations accurately position the galloping of the line by utilizing acceleration sensors, and upload positioning data to the master stations through short-range radio frequency; each master station receives galloping monitoring data from four nearby substations, and uploads the monitoring data and environmental meteorological data to the background monitoring upper computer through a general packet radio service (GPRS); and when each master station synchronizes a clock through a global positioning system (GPS) module, the synchronism of the uploaded data is ensured. The online monitoring system has a small volume, low influence on mechanical properties of the line, high dynamic performance and high data monitoring accuracy, is low in cost, and can work round the clock.

The invention discloses a method for controlling the input of standby power at the power supply side of a hot standby line based on fiber optic channels. In this scheme, station C is applied to the primary main connection of the 110kV inner bridge of a 110kV substation; main wiring. Solve the problems of high capacitive reactive power in substations and grid reactive power reverse, improve the voltage level of substations, prevent local grid voltage from being too high, and improve the overall operation level of the grid. It reduces equipment loss and insulation aging, improves the operating efficiency of the main equipment of the substation, improves the power factor of the substation, and improves the economy of power grid operation. Effectively avoid the occurrence of large-scale blackout accidents when the main power supply line fails permanently, realize the self-healing of the power grid, and improve the reliability of power supply. The invention can be used as the technical guarantee for the special operation mode of the power grid, greatly improves the safety risk control under the special operation mode, and promotes the safe and stable operation of the power grid.

The invention discloses a method for dynamically controlling the state machine of relay protection equipment in an intelligent substation, including defining the state sets of various relay protection equipment in the intelligent substation; defining the control direction of the state transition diagram of the relay protection equipment, forming various relay Electrical protection equipment state transition diagram; define the trigger conditions for the state transition of various relay protection equipment in smart substations; dynamically match the current state of each relay protection equipment in smart substations; complete the dynamic detection of trigger conditions for relay protection equipment state transitions; output The status results of the relay protection equipment realize the status identification of the relay protection equipment of the smart substation; the method provided by the invention can dynamically identify the status of the relay protection equipment of the smart substation, and realize the non-corresponding monitoring and maintenance of the primary and secondary equipment operating status of the smart substation Lay the foundation for the application of security checks.

The invention discloses a method for identifying mountain fires in power transmission lines based on temperature distribution, which comprises the following steps: 1), preprocessing of mountain fire monitoring images and color mode conversion; 2), preliminary judgment of flames based on color features; 3) , Mountain fire feature extraction based on color feature difference; 4), Mountain fire identification based on temperature distribution. The mountain fire identification method of transmission lines provided by the present invention can effectively identify the mountain fire area in the image by considering the inhomogeneity of the temperature distribution of the flame area, and can effectively eliminate interference factors such as sunlight and car lights. The method has clear ideas and is easy to operate , High practicability, can be widely used in the field of transmission line mountain fire monitoring and alarming.

The invention relates to an isolating device for a relay protection secondary loop electrified terminal block. The isolating device comprises a lead clamp, a rotating shaft, a rotating shaft connecting block and a plastic retaining plate, two ends of the rotating shaft connecting block are movably hinged to one sides of the lead clamp and the plastic retaining plate respectively, and both the lead clamp and the plastic retaining plate can swing and rotate around the rotating shaft connecting block. The isolating device is simple in structure, scientific in design, easy to manufacture, low in cost and convenient to operate and use, and mistaken touching and misoperation of the electrified terminal block can be avoided effectively, so that safety risk during inspection of relay protection secondary equipment is lowered; the lead clamp can be fixedly mounted with a lead on one side of the terminal block, so that the isolating device is extremely convenient to fix, working efficiency is improved, using range of the isolating device is expanded, and the isolating device is suitable for popularization and use.

The invention discloses a line backup power input method for hot standby based on a power side contact fiber channel. According to the invention, the problems of the over high capacitive reactive power of a substation and grid reactive reversal are solved, the voltage level of the substation is improved, the over high voltage of a local grid is prevented, and the overall operation level of a powergrid is improved. The equipment loss and insulation aging are reduced, the operating efficiency of the substation main equipment is improved, the power factor of the substation is improved, and the economic efficiency of the power grid operation is improved. The occurrence of a large-scale power outage accident when a main supply line is permanently faulty is effectively avoided, the self-recovery of the power grid is achieved, and the reliability of power supply is improved. The method can be taken as a technical guarantee for the special operation mode of the power grid, the safety risk management and control under the special operation mode is greatly improved, and the safe and stable operation of the power grid is promoted. In the invention, a C station satisfies the following primarywiring including the 110kV inner bridge primary main wiring of a 110kV substation and the 110kV single bus section primary main wiring of the 110kV substation.

The invention discloses an electric power line distance III-section protection misoperation hidden danger eliminating method and device. The electric power line distance III-section protection misoperation hidden danger eliminating method comprises the following steps that phase-to-phase distance III-section protection or ground distance III-section protection enters start-up logic; whether an unsymmetrical fault occurs is judged according to the electrical characteristics of an electric power line, trip of the ground distance III-section protection directly happens when the unsymmetrical fault occurs; trip of the phase-to-phase distance III-section protection directly happens when a symmetrical fault occurs; the electric power line is judged to be overloaded, the phase-to-phase distance III-section protection or the ground distance III-section protection is blocked, and misoperation of the phase-to-phase distance III-section protection or the ground distance III-section protection is avoided when the symmetrical fault occurs. According to the electric power line distance III-section protection misoperation hidden danger eliminating method and device, trip of the phase-to-phase distance III-section protection or the ground distance III-section protection happens when the unsymmetrical fault or the symmetrical fault occurs and the phase-to-phase distance III-section protection or the ground distance III-section protection can be blocked and misoperation of the phase-to-phase distance III-section protection or the ground distance III-section protection can be avoided when the electricity power line overloads.