115 results about "Power-system protection" patented technology

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 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.

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 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.

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.

A power system protection system for preventing 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 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 (I_in) to the zone, continuously measuring all the outgoing currents (I_out) from the zone, continuously calculating the differential current (I_d) according to I_d=I_in−I_out, continuously calculating q=I_out/I_in, continuously comparing q with set values and continuously comparing I_out with a set value Set1. The invention is characterised by setting I_out=I_in=I_comp at the instant when q changes and I_out 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 I_comp 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.

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.