138 results about "Differential protection" patented technology

The invention discloses a protection control method for a differential mechanism of a pure electric vehicle, which relates to the technical field of electric vehicle driving, and comprises the following steps: acquiring wheel speed signals of wheels on two sides of a vehicle driving shaft, and calculating the rotating speed difference of the wheels on two sides; according to the rotating speed difference, a protection torque upper limit value and a protection torque lower limit value under the current rotating speed are determined through a preset rotating speed and protection torque threshold value mapping table; judging whether the motor request torque exceeds the upper limit value or the lower limit value of the protection torque; if the time exceeds the preset activation delay time, activating the differential protection function; and in the state that the differential protection function is activated, the actual output torque is controlled to be between the protection torque upper limit value and the protection torque lower limit value. Abnormal abrasion or impact damage of internal elements of the differential mechanism caused by excessive slip of a single-side wheel can be effectively avoided, so that the service life of the differential mechanism is greatly prolonged, the maintenance cost is reduced, and intense driving control and power requirements are met.

The embodiment of the invention provides a differential relay protection device, equipment, system and method and a storage medium, the differential relay protection device comprises a clock module, the clock module is configured to create a first clock for the differential relay protection device, the first clock is configured in a precision time protocol domain, and the clock module is configured to create a second clock for the differential relay protection device, the second clock is configured in a precision time protocol domain; the second clock and the first clock operate independently; a power data obtaining module configured to obtain power data collected based on a second clock; and a processing module configured to perform a differential relay protection function through the first clock. According to the differential relay protection device disclosed by the invention, an independent precise time protocol domain can be configured for a differential relay protection function, so that power data synchronization is realized in a mode of low hardware cost, low system framework complexity, high flexibility and high operation stability, and the differential relay protection function is realized.

The invention discloses a differential protection function test method and system based on remote data synchronization, and relates to the technical field of power system relay protection tests.The method comprises the steps that host and slave test devices are deployed remotely, and communication is established through standby optical fibers; the host test device responds to the configuration parameters to generate two-dimensional test data, synchronizes the two-dimensional test data to the slave test device and calculates channel delay; based on the FPGA logic architecture and channel delay, the two test devices synchronously output test data to the differential protection device; the system comprises a remote testing device, a differential protection device and a standby optical fiber link, the testing device is integrated with a plurality of functional units such as an FPGA, the method supports fault-tolerant recovery, multi-scene expansion and result analysis, the remote synchronous testing problem is solved, the testing accuracy and comprehensiveness are improved, and the testing efficiency is improved. The method is suitable for substation differential protection function verification.

The invention relates to the technical field of fire sensing, and discloses an electrical fire state sensing system and method for a low-voltage distribution line, and the method comprises the steps: setting a first monitoring point at a wire inlet end of a distribution loop, setting a second monitoring point at a load access end, setting a differential protection region, and calculating a first on-resistance; performing moving average processing on the first on-resistance to obtain a second on-resistance, calculating a first reference on-resistance according to the second on-resistance, and performing temperature correction on the first reference on-resistance to obtain a second reference on-resistance; according to the method, the on-resistance deviation rate, the on-resistance growth rate and the on-resistance fluctuation coefficient are calculated, whether the on-resistance is in an early warning state, an alarm state or a dangerous state is judged, the on-resistance of the section is calculated in real time according to the ratio of the differential voltage drop to the current, and the technical problem that a fault section cannot be accurately positioned through traditional whole-line monitoring is solved.

The application relates to the technical field of differential protection, in particular to a power distribution network distributed differential protection method and system suitable for a 1.4GIGS communication network, which comprises the following steps: based on the current and voltage parameters of each node of the power distribution network, real-time data is extracted and analyzed, the difference between the nodes is calculated, the nodes meeting the conditions are screened out by analyzing the difference values, signal receiving monitoring is carried out, and a list of key monitoring nodes is generated. In the application, the node signal transmission path is optimized through a power distribution algorithm, the time-frequency resource distribution of the signal is dynamically adjusted, the efficiency and stability of signal transmission are realized, the bit error rate in the signal transmission process is effectively reduced, the response speed and accuracy of the power distribution network differential protection system are improved, the interference information in the signal is processed through a particle swarm optimization algorithm, the frequency spectrum structure of the signal is optimized by rearranging and rotating the interference signal, the transmission parameters of the signal are adjusted, and the stability and anti-interference ability of signal receiving are greatly improved.

The invention discloses a current differential protection adaptability analysis method for an alternating current line of a new energy network flexible direct output system, and belongs to the technical field of power system relay protection. Establishing a system fault equivalent model based on a low-voltage ride-through control strategy of power electronic equipment at two sides of the outgoing line; according to different asymmetric fault types and a fault point boundary condition equation, deriving mathematical models of positive-sequence, negative-sequence and zero-sequence currents on the two sides of a fault phase line; calculating a differential current and a braking current, and establishing a function relationship between the differential current and the braking current and the VSG internal potential reference value, the transition resistance and the current sequence component ratio; and the action sensitivity of protection under different working conditions is judged by comparing the current differential protection ratio braking coefficient setting value with the current differential protection ratio braking coefficient setting value. The association rule of the current differential protection refusal risk and the low-pass control parameters under the high transition resistance fault is disclosed, a basis is provided for protection setting and control strategy optimization of a network construction flexible direct output system, and the problems that a protection adaptability analysis method is weak and the influence rule of the control parameters is not clear yet are solved.

The invention discloses a line current differential protection false information detection method based on a delay observer, and is applied to the technical field of line current differential protection. Comprising the following steps: establishing a distribution parameter model of the power transmission line, and discretizing the distribution parameter model to obtain a discrete model of the power transmission line; constructing a delay observer based on the discrete model of the power transmission line, solving a parameter matrix of the delay observer, and estimating a negative sequence voltage predicted value at the current moment; reading a negative sequence voltage measured value at the current moment, and calculating an error between the negative sequence voltage predicted value and the negative sequence voltage measured value; and if the error is greater than a preset error threshold value, judging that the line current differential protection system is attacked by false information injection. According to the method, false information injection can be effectively identified by monitoring the negative sequence voltage prediction error, and the reliability of current differential protection and the safe operation level of a power grid are improved.

Embodiments of the present disclosure provide a data alignment method, a differential protector and a differential protection system. The data alignment method comprises: at a first time node, obtaining first sampled current data from a first sampling device; at the first time node, receiving a second message from a second differential protector, the second message comprising second sampled current data and a sampling time mark thereof, first time information about a receiving time difference of the second differential protector from receiving a first message to the second time node, and second time information about a second sending processing delay of the second differential protector from the second time node to sending the second message, the second time node being a time point at which the second sampling device obtains the second sampled current data; when time synchronization is maintained, calculating and storing a time calculation deviation between a third time node and a first calculation value of the second time node; when time synchronization is lost, determining the third time node according to the stored time calculation deviation.

The present application relates to the technical field of power system relay protection, and particularly relates to a kind of offshore wind power through flexible low-frequency transmission system sending out line protection method, offshore wind farm is connected with modular multi-level matrix converter after being sent out by low-frequency through booster transformer, and is incorporated into large power grid after being frequency converted by M3C. When M3C of offshore wind farm fails, negative sequence current suppression and positive sequence current limiting strategy are adopted for fault ride-through, and relay protection devices are installed at both ends of low-frequency sending out line and communicate. The current sampling values before and after the fault on both sides of the line are reconstructed in phase space, and the difference between the permutation entropies is used to construct a protection scheme, which overcomes the problem of sensitivity reduction of traditional current differential protection for sending out line, reduces the amount of data interaction, and reduces the pressure of protection communication and the requirement of data synchronization. It is not affected by the control strategy of wind turbine and modular multi-level matrix converter at both ends of the line, fault ride-through mode, transition resistance and fault location, and has high reliability and good speed.

The application discloses a kind of dynamic response 5G communication differential protection data transmission method, so that the differential protection service based on 5G communication is widely applied in low-voltage distribution network field, promote the development of new technology of power grid relay protection, solve the protection terminal of traditional low-voltage power grid not dependent on channel cannot give consideration to speed and selectivity requirement, by using advanced 5G communication technology, with the high bandwidth of 5G communication network, low latency and high reliability wireless communication environment, realize the large-scale application of longitudinal differential protection in closed-loop operation low-voltage power grid, improve the protection level of power grid.The application applies dynamic response transmission mode in the communication process of distribution network transmission line differential protection based on 5G communication, meets the rapidity requirement of relay protection, reduces 5G communication transmission flow, saves communication resources and reduces communication cost.

The application discloses a kind of current transformer wire breakage fault positioning processing method and system, method includes: in protection device, additional redundant current transformer;With current mutation variable, real-time calculation N line and current amplitude and N line and current mutation variable amplitude;Set criterion, judge N line and current amplitude whether greater than flow threshold value, identify whether the stable CT wire breakage occurs outside protection device;And, judge N line and current mutation variable amplitude whether greater than mutation variable threshold, identify whether the intermittent CT wire breakage occurs outside protection device;According to the discrimination condition of conventional differential protection CT wire breakage, and in combination with criterion distinguishes wire breakage position, again in combination with three-phase CT sampling balance and distinguish result, determine the phase of specific CT wire breakage and position.The application has less demand to hardware resource, can distinguish whether CT wire breakage occurs in device CT primary side or secondary side, and according to fault position, provide corresponding processing mode.Improves the reliability of differential protection.

The invention provides a composite differential protection method, a control device, a storage medium and a system, and belongs to the technical field of power distribution networks. The method comprises the following steps: after a power distribution network starts differential protection, exchanging electrical quantities measured by protection at two sides of a protected section; predicting the electrical quantities before and after the fault of the protected section by using the exchanged electrical quantities measured by the protectors at the two sides of the protected section; predicting the voltage of a fault point based on the predicted electrical quantities before and after the fault of the protected section, and calculating the action condition of differential protection; and when the calculated action condition of the differential protection meets the requirement, sending a tripping signal to realize composite differential protection. According to the method, the current and the active power of the T-connection DPV and the load branch under the fault are estimated by using the electrical data at the two ends of the protected section, and the protection principle is ensured to accord with the KCL and the active power conservation law, so that the problem of differential protection refusal or maloperation when the T-connection DPV and the load branch exist in the protected section at the same time is solved.

The invention discloses a busbar differential protection test workbench, which relates to the technical field of test devices and specifically comprises a base plate and an upper cover plate, a microcomputer protection tester is placed in the upper cover plate, and a scissor type lifting mechanism is arranged between the base plate and the upper cover plate. The base plate and the upper cover plate can be separated for expansion or close for storage under adjustment of the scissor type lifting mechanism, side baffles are arranged outside the two sides of the base plate and the two sides of the upper cover plate, and semi-open sliding grooves are formed in the side baffles. According to the multifunctional detection platform, in the using process, flexible expansion and automatic limiting can be carried out through the arranged base plate, the upper cover plate, the first supporting rod, the second supporting rod and other structures, the detection supporting requirement is met, in the transferring process, the multifunctional detection platform can carry out storage adjustment of maximum limiting, and the practicability is high. And the occupied area is reduced, and meanwhile the flexibility in the transferring process can be fully improved.

This invention discloses a communication configuration method, device, electronic equipment, and storage medium for differential protection of distribution network ring networks, belonging to the field of power automation technology. The method includes: disconnecting all differential protection circuits within the first target differential ring where the fault differential protection device is located; disconnecting the optical fiber link between the fault protection device and other differential protection devices; after replacing the fault differential protection device with a new differential protection device, restoring the optical fiber link between the new differential protection device and other differential protection devices; controlling the static routing table corresponding to the first target differential ring to be updated, setting the differential protection activation identifier of the first target differential ring in the static routing table, and the differential protection activation identifier of each differential protection device within the first target differential ring, to the corresponding activation status identifier. Therefore, by implementing this invention, the problems of existing technologies that rely on manual on-site parameter setting, resulting in high cost and low reliability can be solved.

The invention provides a converter transformer fault inrush current suppression circuit and method of a circuit breaker additional thyristor pair, and relates to the field of power system relay protection, and the method comprises the steps: controlling a current to access a starting resistor after receiving an MMC starting signal, and carrying out the pre-charging protection of a capacitor; in response to the detected normal operation signal, continuously acquiring current amplitude data and starting resistor temperature data, and performing bypass control adjustment according to the current amplitude data and the starting resistor temperature data; the load change is pre-judged, and the emission time and width of a thyristor trigger pulse are adjusted to obtain a smooth transition strategy; in response to detecting the fault signal, the trigger pulse of the thyristor pair is removed for suppressing the fault inrush current. According to the method, the fault inrush current amplitude is rapidly reduced, development of the fault inrush current is inhibited, and correct action of differential protection of the converter transformer is ensured.

The invention discloses a busbar differential protection capacity expansion method and system and a storage medium, and belongs to the technical field of power system relay protection. The method is applied to a double-bus wiring system configured with two sets of redundant bus differential protection devices, and the core is a differential transformation scheme: firstly analyzing hardware configuration and branch distribution conditions of the two sets of devices, directly adding a branch to a device with spare resources, and accessing a newly-added main transformer interval; and for the device with the full branches, the access position is vacated by adjusting the branch distribution of the existing incoming line interval and the main transformer interval. In the construction process, short circuit is carried out first and then reconnection is carried out to guarantee the safety of a current loop, and hardware wiring optimization, protection program upgrading and function verification are matched to complete transformation. The corresponding system comprises the bus differential protection device transformed by the method, and a computer readable storage medium for storing a program upgrading step. The whole set of equipment does not need to be replaced, the existing hardware redundancy expansion function is utilized, the modification cost is low, the safety risk is small, and the flexibility is high.

The application discloses a kind of quick transformer protection method and system using sampling value, wherein the method comprises: according to the sudden change variable sampling value of each side current of transformer, the sudden change variable differential current and sudden change variable virtual differential current of transformer are calculated;Based on the sudden change variable differential current and sudden change variable virtual differential current, constitute sudden change variable sampling value inrush blocking criterion;Based on the sudden change variable differential current, constitute sudden change variable sampling value differential protection;Differential current is determined, and based on the differential current, constitute developing fault release inrush blocking criterion;Based on the sudden change variable sampling value inrush blocking criterion and inrush blocking criterion, transformer sampling value differential protection timing.

The invention provides a line pilot current differential protection joint debugging acceptance method and a related device, and belongs to the field of power system power transmission line protection. The method is used for joint debugging of longitudinal current differential protection channels on the two sides of a power transmission line, and in the implementation process, optical fiber data, electrical quantity data, a protection device version number and protection pressing plate data are firstly obtained. And judging whether the channel is normal based on the optical fiber data, if so, simulating various working conditions for the protection device and the pressing plate on any side of the channel, and checking the static characteristics of the channel according to the electrical quantity on the other side and the feedback of the protection pressing plate data. When the states of the channels on the two sides are checked to be correct, line protection device channel joint debugging is carried out, and dynamic behaviors are checked according to protection action conditions on the two sides. And finally, generating a joint debugging acceptance report corresponding to the version number of the protection device in combination with an inspection result. Through automatic data acquisition, analysis and report generation processes, the dependence on manual subjective judgment can be reduced, and the accuracy and consistency of test results are improved.

This invention provides a differential protection testing method and system for converter transformer valve groups based on fault process simulation, belonging to the technical field of differential protection testing for converter transformer valve groups. The testing method includes parameter configuration via human-machine interaction; acquiring status data of the DC protection device during normal operation; and, by acquiring data from the DC protection device during normal operation and fault data under various fault conditions, discretizing this data, and then simultaneously sending the AC-side and DC-side discrete data to the DC protection device for sequential differential protection characteristic testing. This enables the testing of the valve group's differential protection characteristics, ensuring more reliable operation of the DC protection device and improving the safety of the protection system.

The embodiment of the invention provides a motor differential control method and device, motor driving equipment and a storage medium, and the method comprises the steps: controlling the rotating speed of a main motor and the rotating speed of a slave motor in real time according to the theoretical rotating speed difference value and the actual rotating speed difference value of the main motor and the slave motor; the rotating speed of the left motor and the rotating speed of the right motor can be controlled in time under the condition that the deviation between a theoretical rotating speed difference value and an actual rotating speed difference value is too large due to the fact that a certain motor of the motor driving equipment cannot rotate or the rotating control precision of the double-drive equipment is reduced, and the safety of operators is guaranteed; and an operator does not need to frequently adjust the advancing direction of the double-drive equipment, so that the technical problem that the operator needs to frequently adjust the advancing direction of the double-drive equipment when a fault occurs under the condition that the double-drive equipment lacks a differential protection mechanism in the prior art is solved.

The application provides a transformer differential protection method and system based on a fault negative sequence component direction. The method comprises: judging whether a fault negative sequence component direction discrimination element meets a first discrimination condition; judging whether a proportional differential element meets a second discrimination condition; and starting a transformer differential protection action in the case that the fault negative sequence component direction discrimination element meets the first discrimination condition and the proportional differential element meets the second discrimination condition. The protection method does not block through the transformer excitation inrush current, ensures that the fault is quickly removed in the case of an internal fault, the protection action time is less than three quarters of a cycle, and the protection action is not mis-operated in various external faults and abnormal operating conditions.

The invention belongs to the technical field of electrified railway traction power supply, and particularly relates to a traction network multi-terminal longitudinal differential protection system and method in a bilateral through AT power supply mode. The system is provided with multi-terminal longitudinal differential protection elements according to uplink and downlink feeder lines, multi-terminal branches formed by traction substations, AT stations and partition stations are covered, and each branch is provided with a current transformer. The protection element comprises a power frequency variable quantity current differential element, a T line / F line current differential element and a low-voltage differential current starting element which are respectively adaptive to fault transient state and steady state characteristics, and rapid fault identification and accurate fault removal are realized through cooperative action. The method combines a current threshold criterion, a voltage criterion and an opposite-side permission signal, ensures the action quickness, selectivity, sensitivity and reliability, realizes quick removal of power supplies at two ends of a fault, reduces the fault isolation range, and ensures safe and stable operation of a traction network.

The application provides a kind of double busbar bus differential protection processing method, device and equipment, method includes: obtaining the state information of bus coupler switch and the polarity requirement information of bus coupler current transformer;According to the polarity requirement information, obtain the input information in the function soft pressure plate of protection device;According to state information and input information, obtain the bus coupler current coefficient of each bus;According to the bus coupler current coefficient of each bus, obtain the small differential operating current of each bus;According to the small differential operating current of each bus and the preset setting value, control protection processing is carried out to each bus.The scheme of the application can realize the polarity self-adaptation of protection device, ensure the calculation accuracy of the small differential operating current of each bus, avoid the abnormal differential flow of protection device to alarm or even malfunction, without changing the secondary wiring mode of current transformer, reduce the workload of substation technical improvement, and improve the work safety and work efficiency.

The invention provides a bus differential protection in-operation multi-frequency fingerprint self-inspection and branch saturation discrimination suppression method. The method comprises the following steps: collecting the current of each branch of a bus and respectively calculating the three-phase differential current and brake current of each branch; performing frequency domain analysis on the differential current and each branch current to obtain a bus on-operation multi-frequency fingerprint based on fundamental wave and multi-order harmonic amplitude; determining a saturated branch by judging whether a current transformer of each branch is subjected to transient saturation or not based on the bus in-operation multi-frequency fingerprint; a fault causing saturation is processed based on the branch where saturation occurs, the differential current, and the braking current to suppress branch saturation. According to the method, the specific branch with CT saturation is positioned by using the bus in-operation multi-frequency fingerprints, and the fault area is judged in combination with the differential current amplitude, so that branch-level saturation identification is realized; however, in the prior art, CT saturation can only be detected integrally and cannot be refined to a single branch. According to the invention, protection operation rejection possibly caused by simple hard locking is avoided, maloperation is avoided, and sensitivity and safety are both considered.

The application discloses an energy integral differential protection method and system based on a distribution parameter model, which comprises the following steps: collecting three-phase voltage and three-phase current instantaneous values of a line at a local side and an opposite side in real time; calculating three-phase current calculation values of the local side at the same time based on the three-phase voltage and three-phase current instantaneous values of the opposite side; calculating three-phase current difference currents based on the three-phase current instantaneous values of the local side collected in real time and the three-phase current calculation values of the local side at the same time; calculating three-phase differential current operating quantities based on the three-phase current difference currents; and forming an energy integral differential protection operating criterion by using the three-phase differential current operating quantities, and performing differential protection when the three-phase differential current operating quantities meet the differential protection operating criterion. The application solves the problems of frequency deviation and harmonics of traditional Bergeron phasor differential protection after faults of power electronic devices such as new energy and flexible direct current, and improves the differential protection operating performance in a new energy power transmission scene.

The application discloses a ferromagnetic saturation and inrush current discrimination method and device reflecting concave-convex offset of current waveform, and the method comprises the following steps: obtaining three-phase differential current waveform according to three-phase currents of each side of a transformer, and collecting variation sequence of three-phase differential currents of the transformer based on the three-phase differential current waveform; calculating current variation difference, absolute value of the current variation difference, current period integral of the current variation difference, current period integral of the absolute value of the current variation difference, T / 3 period integral, 2T / 3 period integral and maximum number of two points of the absolute value of the current variation difference; when the sum of the T / 3 period integral, the 2T / 3 period integral, the maximum number of two points of the absolute value of the current variation difference, the absolute value of the current period integral of the current variation difference satisfies the ferromagnetic saturation and inrush current criterion reflecting the concave-convex offset of the current waveform, the inrush current or CT saturation is determined, and the differential protection is blocked. The same criterion is used, and effective identification of the inrush current and the saturation is realized.

The application discloses a self-synchronization current differential protection method suitable for a cable-overhead line hybrid transmission line and related devices. The method comprises the following steps: constructing a complete distributed parameter matrix model of the hybrid line; before a fault occurs, performing non-synchronous phase angle compensation on sampling values at two ends, determining an optimal compensation angle by traversing search of minimum differential current variance, and realizing self-synchronization; calculating three-phase differential currents and braking currents based on the synchronized electrical quantities; and adopting a proportional braking criterion to identify an in-zone fault. The device comprises a data acquisition module, a model construction module, a self-synchronization module, a fault detection module and a protection action module which are connected in sequence. Through accurate modeling and self-synchronization technology based on pre-fault data, the application effectively solves the problem of poor protection reliability caused by different parameters of the hybrid line and different sampling at two ends, can quickly and accurately identify an in-zone fault, and is suitable for hybrid line scenes of offshore wind power transmission and urban power grids.

The application discloses a network construction / following network type wind farm current and differential protection method based on equivalent short-circuit current in the field of power system relay protection, and aims to solve the technical problems of low short-circuit current level, strong nonlinearity caused by inverter amplitude limiting control of a wind farm, and insufficient sensitivity and reliability of traditional protection. The method comprises the following steps: calculating a pre-fault modulation coefficient and an AC internal potential based on pre-fault steady-state parameters and a pre-built equivalent model, and setting a three-section current protection value according to the pre-fault modulation coefficient and the AC internal potential; if the setting does not meet the requirements, starting protection, collecting post-fault parameters and calculating a post-fault modulation coefficient; restoring the post-fault AC internal potential to the pre-fault level by using the ratio of the pre-fault modulation coefficient to the post-fault modulation coefficient, and then generating an equivalent short-circuit current; finally, comparing the equivalent short-circuit current with a preset value to realize fault identification and judgment. The application can effectively improve the sensitivity and reliability of protection in a low short-circuit current scene, and accurately perform fault positioning and removal.

The utility model relates to a fan engine room dry type variable resistance relay protection device, apply to dry type transformer, including differential protection relay, first current transformer, second current transformer and third current transformer, dry type transformer is three winding transformer, first current transformer, second current transformer and third current transformer are all through -core type current transformer, the high voltage side of dry type transformer is connected high voltage side bus through high voltage side circuit breaker, the normally open contact of differential protection relay connects the tripping loop of high voltage side circuit breaker, the first current transformer is set in the high voltage side wire outside, the second current transformer is set in the medium voltage side wire outside, the third current transformer is set in the low voltage side wire outside, the output of first current transformer, the output of second current transformer and the output of third current transformer connect the differential coil of differential protection relay, the utility model discloses can cut out transformer low voltage side fault in time.

The application discloses a line differential protection method, which comprises the following steps: receiving, by a local side in a line, opposite-side current data and opposite-side switch data transmitted by 5G communication after detecting a fault signal and performing a whole-group start; wherein the opposite-side switch data comprises PT state switch data and CT state switch data; judging whether the opposite side meets a differential permission condition according to the opposite-side switch data; if the opposite side meets the differential permission condition, performing differential operation; and when an operation result of the differential operation meets a differential action condition, performing differential action. In the application, the current data and the switch data are transmitted between the opposite side and the local side by 5G communication, the differential permission condition is judged locally, the number of times of data transmission between the local side and the opposite side is reduced to a certain extent, the speed of differential action is ensured, and the safety of line operation is improved. The application also provides a line differential protection device, a line differential protection system and a computer readable storage medium.