115 results about "Power-system protection" patented technology

An automatic configuration tool for use with power protection and restoration devices such as reclosers and switches in power transmission and distribution systems. An automatic configuration application provides a plurality of menus to a user on a graphical user interface to enable the user to select a plurality of options that are processed by various calculation engines to determine the configuration settings for a specific power protection and restoration device. The configuration settings that are generated are downloaded directly into the power protection and restoration device to provide protection, control and monitoring.

A continuous grounding system for use in an alternating current system including a transformer is disclosed. The system includes a switch assembly connected between a transformer neutral of a transformer and a ground, the switch assembly having an open position and a closed position, the open position disrupting the path through the switch assembly between the electrical connection and the transformer neutral, and the closed position establishing a path connecting the electrical connection to the transformer neutral through the switch assembly, wherein in normal operation of the alternating current electrical device the switch assembly remains in a closed position. The system also includes a DC blocking component positioned in parallel with the switch assembly and connected between the transformer neutral and the ground. The system further includes a control circuit configured to control the switch assembly, the control circuit including a sensor configured to actuate the switch assembly to an open position upon detection of a predetermined harmonic signal threshold at one of the transformer phases or a predetermined threshold of DC current between the transformer neutral and ground.

The invention provides a common-tower double-transmission-line non-cross-line fault ranging method only utilizing single-end information and belongs to the technical field of power system protection and ranging. When one loop of a common-tower double-transmission-line power transmission line fails, a phase-mode matrix is used to decouple coupled phasors of two loops to obtain independent line-mode components of the two loops; analyzing a line-mode fault component network, using fault loop initial-end voltage and current fault component to calculate voltage of fault points and tail-end voltage, using tail-end boundary conditions of a line to calculate voltage of fault points, writing a fault positioning function according to the fact that fault point voltages at two ends are equal, and solving the positioning function to calculate fault distance.

A transmission line single-phase grounding fault single-end ranging method belongs to the field of power system protection and control. According to the method of the invention, positive, negative and zero sequence voltage and current phasors of a line during the time section between the occurrence of a single phase grounding fault and single phase tripping and the time section between single phase tripping and reclosing are measured at a substation protection installation site and are used as input. The initial value of fault distance is set from 0 to the overall length of the line with delta1 as the step length, and the initial value of transition resistance starts from 1 ohm and increases to 1000 ohms with 1 ohm as the step length. For each combination of the values of fault distance and transition resistance, the equivalent electromotive force values of a system at the opposite end of the line during the time section between the occurrence of the single phase grounding fault and single phase tripping and the time section after single phase tripping are respectively calculated, the sum of absolute errors of the equivalent electromotive force values is calculated, and the fault distance value corresponding to the minimum value of the sum of absolute errors is selected as the fault ranging distance. The method is high in precision, is not affected by distributed capacitive current, transition resistance, load and system impedance and has very high practical values.

The invention discloses a boundary protection method for a multi-terminal flexible DC power grid based on voltage of DC reactors, and belongs to the technical field of power system protection. The boundary protection method is characterized in that measurement sampling is performed on voltage of each DC reactor on each DC line on the basis that both ends of each DC line in the DC power grid are provided with the DC reactor, and the measured voltage of the DC reactor is compared with a set protection start threshold to judge a line fault; DC line boundary protection is constructed by using thevoltage of the DC reactor at the single end, fast detection and recognition for a fault can be achieved according to the voltage of the DC reactor at the single end, and communication is not required.In addition, the boundary protection method is simple in theory and does not need complex algorithms, thereby recognizing a DC line fault quickly and reliably, being low in requirement for the sampling rate, not being influenced by the line distribution capacitance, being easy to implement, and greatly reducing requirements for the hardware. The boundary protection method provides an effective method for recognizing a DC fault of the multi-terminal flexible DC power grid.

The invention discloses an uninterrupted power supply system for a relay protection device. The power supply system can continuously supply power to the protection device for a period of time when an outer power supply system of the relay protection device is instable or failed so as to prolong the working time of the relay protection device and the power supply drop resistance time and timely record electric quantities before and after power supply drops, and thus accident analysis can be facilitated. An energy storing element adopts a mature super capacitor; and compared with a lithium battery, the mature super capacitor is maintenance-free and has longer service life. Charging and discharging processes and a voltage monitoring part are controlled by a singlechip which can be made into a power supply plug-in installed in the device. The uninterrupted power supply system can also be applied to devices of other fields so as to guarantee uninterrupted power supply.

The invention relates to the technical field of power system protection and control, in particular to a direct current transmission fault recovery control method and system for avoiding continuous commutation failure. The method comprises the following steps of: when a short-circuit fault occurs in a receiving end alternating current power grid, starting low-voltage current-limiting control, and determining a direct current control instruction value by the low-voltage current-limiting control; when the fault of the receiving end alternating current power grid is cleared and the change rate ofa converter bus voltage of an inverter station is smaller than a set starting threshold value, according to the maximum direct current meeting reactive exchange expectation and the maximum direct current meeting commutation margin, calculating a direct current control instruction value on line to avoid continuous commutation failure in the recovery process of the direct current transmission system; and when the change rate of the converter bus voltage of the inverter station is determined to be smaller than a set exit threshold value, restarting the low-voltage current-limiting control. According to the invention, the alternating voltage recovery process can be improved by dynamically adjusting the direct current, the continuous commutation failure in the fault recovery stage can be inhibited, and the stable recovery of the direct current power is facilitated.

The invention discloses an MMC sub module circuit with a DC-side fault blocking ability, which relates to the field of power system protection control and has the advantages that short circuit current can be completely locked, the structure is simple, the needed elements are few, and integration is high. The MMC sub module circuit with a DC-side fault blocking ability comprises two half bridge sub modules, a first power switch tube with an antiparallel diode and a diode, wherein one half bridge sub module is connected with the emitter of the first power switch tube with the antiparallel diode, and the other one is connected with the collector of the first power switch tube with the antiparallel diode; the negative electrode of the diode is connected with the collector of a second power switch tube with an antiparallel diode in the half bridge sub module connected with the emitter of the first power switch tube with the antiparallel diode, and the positive electrode is connected with the emitter of a third power switch tube with an antiparallel diode in the other half bridge sub module. the product has a small size, and stability is high; the topological structure is simple, the cost is low, and realization is easy; configuration is flexible power consumption is reduced; and the DC side can be broken in the case of short cirucit, and the response is quick.

The invention relates to a protective circuit, a protective method and a software realizing method for portable terminal low-power system protection, and is applied to embedded mobile terminal equipment with a power supply management module. The core logical circuit in the invention comprises a power supply management module, a power supply switchover module, a battery and a minimum system, wherein when the battery power is insufficient for the whole system through the power supply management module, and the system detects that voltage is lower than a threshold valve, the power supply management module is closed, and the battery directly supplies electricity for the minimum system through voltage conversion. The protective circuit closes power supply for the system by closing the power supply management module, and software is not required to close each path of power supply; the power supply voltage of the minimum system is far lower than the work voltage required by normal startup of the system in general condition, and power supply of the power supply management module is converted to direct battery power supply through a hardware circuit, so that the data is protected under a condition that the mobile terminal battery is insufficient in power.

The invention relates to a generator protection device based on a closed-loop marine power system, which solves the problem of closed-loop power system protection which cannot be realized by the existing protection methods. Each generator protection device collects the data related to the operation state, processes the algorithm according to the power system distribution and the internal model ofthe generator protection device, and realizes the fault monitoring and fault determination of each component in the power system. According to the fault judgement, the executing signal of cutting offthe fault circuit or removing the damaged circuit is output to the actuating element to ensure the continuous power supply of the non-fault circuitso as to achieve the goal of providing electricity for as long as possible from as few generating units as possible; through the action command output by the self-protection algorithm and the in-depth grasp of the working characteristics of the generator set, it is ensured that when the generator set fails or the healthy generator set reaches the imminent fault boundary, only the fault loop is removed as soon as possible to minimize the fault coverage, and at the same time, the selectivity of the system and the continuous power supply of the non-fault loop are ensured to the maximum extent.

A power system protection system prevents a voltage drop resulting from the reactive power characteristic of a power system. A main device for acquiring a system electric quantity of one or a plurality of upper substations detects a voltage drop resulting from the reactive power characteristic of the power system and transmits a detection signal of the voltage drop to a terminal device for acquiring a system electric quantity of one or a plurality of lower substations. Each terminal device sequentially sheds loads starting from those suffering more from the influence of the voltage drop resulting from the reactive power characteristic based on the load voltage and load current of a load bus.

The invention relates to a cross-region power system protection communication network planning method, comprising the steps of initializing a first generation of populations through adoption of a variable-length chromosome coding method; setting a fitness function, and evaluating fitness of chromosomes according to features of target populations; selecting parental chromosomes according to the fitness function, specifically, selecting the parental chromosomes through adoption of a selection operator, thereby enabling the parental chromosomes to be inherited by a next generation; carrying out cross processing on the parental chromosomes, and generating new chromosomes, thereby improving diversity of species; carrying out variation processing on the parental chromosomes after the cross processing, thereby improving searching capability of the populations; and combining the parental chromosomes and the newly generated chromosomes, as descendants of a current generation of populations, carrying out a next round of evolution until the preset generation number is realized, exiting a loop, and obtaining a final planning scheme, namely the chromosomes with the highest fitness in the last generation of populations. According to the method, a demand of line protection business for delay can be satisfied.

The invention relates to a test method for the lockout function of the bus protective composite voltage, and belongs to the technical field of power system protection. Sequence components of positive-sequence low voltage, negative-sequence overvoltage and zero-sequence overvoltage of the composite voltage are set according to a fixed value of the bus protective composite voltage; three-phase voltage amplitude and phase angle are distributed by utilizing the symmetrical component principle, so that the different sequence components and protective logic behavior do not interfere with each other; and a fault quantity which satisfies the experiment requirements is calculated, and the lockout function of the bus protective composite voltage is tested according to the fault quantity. According to the bus protection standard, it is not required to modify the fixed value of the composite voltage sequence components, the three-phase voltage amplitude and phase angle are distributed by utilizing the symmetrical component principle, the different sequence components and protective logic behavior do not interfere with each other, and the fault quantity which satisfies the experiment requirements is calculated; and thus, the protection performance is tested and verified, and the test efficiency of onsite protectors is improved.

An apparatus and method for protecting a power system comprising a generator providing power to an alternating current bus, a power converter for converting alternating current power on the alternating current bus to direct current power on a direct current bus, and a direct current load powered by the direct current power on the direct current bus. An undesired condition is identified at the input to the power converter from the alternating current bus. The undesired condition is caused by at least one of the power converter, the direct current bus, or the load. The power converter is disconnected from the alternating current bus in response to identifying the undesired condition for at least a time delay. The time delay is selected such that the power converter is disconnected from the alternating current bus before the alternating current bus is disconnected from the generator due to the undesired condition.

The invention discloses a method for calculating an optimal repair cycle of a relay protection device in view of software and human factors, and belongs to the technical field of power system protection. The method comprises the steps as follows: listing out all the states of the relay protection device, which includes software failure and the human factors, and establishing a Markov state transition diagram; determining parameters in a Markov model according to practical measurement data of a power grid; obtaining an unavailability calculation formula of the relay protection device according to the established Markov model, that is, the relation between the unavailability and the repair cycle; and calculating the repair cycle corresponding to the minimal unavailability according to the relation between the unavailability and the repair cycle, that is, the optimal repair cycle of the relay protection device. According to the method, the software and the human factors are considered, so that the fault state of the delay protection device can be more accurately reflected, so as to enable the optimal repair cycle to be calculated more accurately.

The invention belongs to the technical field of power system protection and control, in particular to a hybrid method of distributed grid-connected island detection. The method comprises the followingsteps: acquiring the voltage value of a common coupling point of a distributed grid-connected power generation system; performing wavelet transform on the collected voltage value, and calculating theaverage value of absolute values of wavelet coefficients in a voltage period; taking the average value as the input signal of a BP neural network, and carrying out pattern recognition by the BP neural network; when the distributed grid-connected power generation system is judged to be in a suspected island state according to the output result of the BP neural network, detecting whether the voltage of a grid-connected point is superimposed with a set carrier signal; when the set carrier signal is detected, judging that the distributed grid-connected power generation system is in the island state. The method combines a wavelet neural network and the carrier communication technology to detect whether the distributed grid-connected power generation system enters into the island state, improves the island identification rate and the reliability of island detection, and has no detection blind area.

The invention belongs to the field of power system protection and control and relates to an urban distribution network voltage regional active control method with a high proportion of controllable source and load. The method comprises dividing a distribution network into a plurality of autonomous regions; according to the amount of change in the regional active power caused by the power active output and load fluctuation, evaluating the capability of the controllable active capacity and the controllable reactive capacity of the autonomous regions to suppress the influence of the active power change on the node voltage; according to an evaluation result, calculating the active and reactive power control reference values of a gas turbine, a wind power source, a photovoltaic power source, storage energy and an electric vehicle charging pile by using a regional active power optimization model, a regional reactive power optimization model, and a regional active and reactive power coordinated optimization model; and when the node voltage in the regions exceeds an allowable range, switching the control reference values to the calculated power reference values so as to implement active active power control, active reactive power control or power active coordinated control separately.

The invention discloses a marine nuclear power platform electric generator stator grounding fault degree diagnosis method and system, and belongs to the field of marine nuclear power platform power system protection. According to the method, an electric generator stator grounding fault diagnosis function integrating grounding fault current and system overvoltage is established, and the harm degree of electric generator stator winding grounding faults to electric generator operation safety and power distribution network insulation safety can be reflected at the same time; effective reference is provided for implementation of a self-adaptive electric generator tripping control mode according to the fault degree for marine nuclear power platform electric generator stator grounding protection, safe operation of a marine nuclear power platform electric power system is guaranteed, and technical reference is provided for other electric generator stator grounding protection improvement methods.

An automatic configuration tool for use with power protection and restoration devices such as reclosers and switches in power transmission and distribution systems. An automatic configuration application provides a plurality of menus to a user on a graphical user interface to enable the user to select a plurality of options that are processed by various calculation engines to determine the configuration settings for a specific power protection and restoration device. The configuration settings that are generated are downloaded directly into the power protection and restoration device to provide protection, control and monitoring.

The invention relates to a quick adjustment method for a parallel line branching factor in a substation area distance protection section III, and belongs to the field of a power system protection and control technology. The method comprises the steps of judging whether a protective starting line is a parallel line structure, quickly modifying the parallel line branching factor if the protective starting line is a parallel line structure and trip or switch on is caused, and then calculating a distance ground section III and a phase distance ground connection III in accordance with a current protective setting value after the definite value of the distance section III is quickly modified, and judging whether fault is caused; directly performing protection algorithm processing if the protective starting line is not a parallel line structure. According to the quick adjustment method provided by the invention, the contradiction of the substation area distance protection section III in flexibility and selectivity can be overcome; furthermore, a parallel line running condition can be quickly adjusted, so as to improve the reliability of the motion in the substation area distance protection section III.

The invention relates to a protection device and in particular to a multifunctional power system protection device comprising a multifunctional moving wheel mechanism, a protective casing mechanism, an anti-collision dust-cleaning seat mechanism, a cable peeling mechanism, and a cable cutting mechanism. The device can switch between a flat ground driving mode and a rough road driving mode, can bechanged in height, can dissipate heat, can prevent the system from being polluted by dust, can clean the dust of a filter screen, can avoids colliding, can be easily disassembled, and can peel a cable, can cut the cable, and can protect a cutting blade. The multifunctional moving wheel mechanism is located below the protective casing mechanism, and is welded to the protective casing mechanism. Theanti-collision dust-cleaning seat mechanism is welded to both sides of the protective casing mechanism. The cable peeling mechanism is welded to the protective casing mechanism. The cable cutting mechanism is welded to the protective casing mechanism.

The invention relates to the field of power system protection and control, and provides a method for determining upper limit values of various sequence output current in view of shortage of corresponding researches on determination of various sequence current limiting values under a dividing-sequence control strategy of a three-phase four-leg inverter. According to the method, development of the maximum voltage balancing ability of the inverter can be ensured. Therefore, according to the adopted technical scheme, a control method of a three-phase four-leg grid-connected inverter with an adaptive current limiting function comprises the steps of calculating the sun of various phases of negative sequence current and zero sequence current under unified two-phase synchronous rotating coordinates and calculating the maximum value of the sequence current according to actual upper limit values of various phases of current, namely the maximum carrying current of a power electronic switching device of the inverter, so that the inverter can develop the maximum voltage balancing ability under the condition that various phases of current do not exceed the maximum value. The control method is mainly used for power system protection and control occasions.

The invention discloses a calculation method and device for circulating current in a delta winding of a Y / △ transformer, belonging to the technical field of relay protection for main equipment of a power system. The methods include: obtaining the winding resistance and leakage inductance on both sides of the Y / △ transformer; obtaining the zero-sequence voltage on the Y side or measuring the three-phase winding voltage on the Y side; obtaining the zero-sequence current on the Y side or measuring the three-phase winding current on the Y side ; Use the winding resistance, leakage inductance, three-phase winding current and three-phase winding induction potential on both sides to list the three-phase winding voltage equations on both sides; calculate all equations according to the relationship between each parameter, and eliminate them except △ All unavailable parameters except for the circulating current in the side winding yield the circulating current. The device includes an acquisition module, a voltage calculation module and a circulation calculation module. The invention can calculate the circulating current in the delta side winding when the current transformer is not used in the delta side winding of the transformer, thereby calculating the equivalent instantaneous inductance of each phase of the transformer, and further distinguishing the excitation inrush current of the transformer.

The invention relates to a high-frequency arc modeling method for a circuit breaker, and belongs to the technical field of power system protection and fault monitoring. According to the method, a three-section type arc whole process model is built according to changes of arc currents at different moments. A pre-arcing stage is represented by using a conventional time-varying resistor model; a steady-state arcing stage is represented by using a settable fixed resistance value; and an arcing stage is represented by using a Mayr arc model. The arc modeling method provided by the invention can provide a theoretical basis for arcing fault early warning and identification of the circuit breaker.

The present invention relates to a method for current compensation of a protection system for protecting a zone in a power system, which zone comprises a number of transmission lines connected to power sources and a number of transmission lines connected to a number of loads where the power sources and the loads are arranged outside the zone and a number of current transformers (CT) arranged to the transmission lines, wherein the method comprises the steps of continuously measuring all the incoming currents (Iin) to the zone, continuously measuring all the outgoing currents (Iout) from the zone, continuously calculating the differential current (Id) according to Id=Iin−Iout, continuously calculating q=Iout / Iin, continuously comparing q with set values and continuously comparing Iout with a set value Set1. The invention is characterised by setting Iout=Iin=Icomp at the instant when q changes and Iout exceeds the value set1, which is an indication of the occurrence of a fault external to the protection zone due to saturation of the CT of the faulted outgoing transmission line, and using the value Icomp in the protection system in order to prevent tripping of the protection system. The present invention also relates to a device and a computer program product for performing the method.

A protective relay and power system protection method which incorporates multiple user-selectable communications protocols over multiple communications ports. The relay can support multiple communications protocols over a single communications port, and can support simultaneous formatting and communication over multiple communications ports using different protocols. By supporting a full array of communication protocols in each relay, protective control functionality is enhanced.

The invention discloses a switch cabinet system used for a fuse type isolation switch, belonging to the power system protection electric appliance technology field. The switch cabinet system comprises a recognition unit, a monitoring unit, a driving unit, a control unit, a wireless communication unit and an information management platform. The recognition unit is connected to the control unit through the wireless communication unit for identifying and marking position information of various members inside the switch cabinet; the monitoring unit is connected to the control unit through the wireless communication unit for monitoring voltage, current, discharge, contact temperature and fault signals inside the switch cabinet; a driving unit is connected to the control unit through the wireless communication unit for switching off the switch of a faulted point inside the switch cabinet and starting up a fan inside a driving unit for cooling; and the control unit is connected to the information management platform through an optical fiber network. The switch cabinet system used for a fuse type isolation switch solves the problem that switch cabinet fault information is not promptly displayed and prompted, can perform comprehensive determination on the operation state of the switch cabinet, and realizes the self-checking of the switch cabinet, self-diagnosis and self-operation.

The invention relates to a UHV DC line fault identification method with the use of filter branch current and a fractal box dimension, belonging to the technical field of power system protection. When a DC line is failed, the filter branch measuring end is used to obtain current data. K (k is larger than or equal to 2) squares with the side length of epsilon 1, epsilon 2 to epsilon k are selected to cover current i(t), and the box dimension D of the current i(t) is obtained. Finally, DC line area inner and outer faults are identified according to a condition whether the box dimension D is larger than a fixed value Dset. According to the method of the invention, a 'relative mode' is used to measure the characteristic of a fault waveform, the ability of resisting transition resistance is strong, and the accuracy is high.

The invention relates to the field of relay protection of power systems, in particular to a CT polarity tester. It includes: a power supply circuit, a voltage stabilizing circuit, an output circuit, and an infrared remote control circuit; among them, the power supply circuit includes: solar panels and batteries connected in series; the positive and negative poles of the battery are connected to the output circuit; the output circuit includes: A connection line, a second connection line connected to the negative pole of the storage battery, the first connection line includes the first positive terminal and the second positive terminal connected in parallel, the second connection line includes the first negative terminal; the two ends of the voltage stabilizing circuit are respectively The first connection line and the second connection line are connected; the infrared remote control circuit is connected to the output circuit. The invention can form a stable input voltage and obtain accurate test results.