290results about How to "Quick resection" patented technology

The invention relates to an adaptive cascade direction interlocking relaying method based on GOOSE (Generic Object Oriented Substation Event), which comprises the following steps: 1) initial interlocking directions of protective relays are set according to an initial interlocking direction tuning rule; 2) a directional element judges the direction of a current fault current which is compared with the initial interlocking directions by a direction comparator to judge whether the directions of two parts are the same, if yes, the step 3) is carried out, if not, IN2 is gated, and a interlocking signal is output to OUT2; 3) the direction comparator gates IN1, and outputs the interlocking signal to the OUT1 and the direction of the output signal is opposite from the initial interlocking direction at this time; 4) a receiving virtual terminal judges whether the interlocking signal is received, if yes, the interlocking is carried, if not, the step 5) is carried out; and 5) an over-current element judges whether the current fault current exceeds a local over-current protection starting fixed value, if yes, a trip signal is sent. In comparison with the prior art, the method has the advantages that the safe and reliable operation of a system is ensured and applicability is good.

The invention relates to a relay protection method capable of quickly removing dead zone fault of a transformer. The relay protection method includes: during trip control of dead zone fault of one side of the transformer, setting conditions including a first condition and a second condition; if all the conditions are met, disconnecting a differential TA on the side of the transformer after delaying by a constant value, namely preventing current of the side of the transformer participating differential protection current calculation; if no conditions are met, then connecting the differential TA on the side of the transformer immediately, namely allowing current of the side of the transformer to involve in differential protection current calculation of the transformer. The first condition is that a spare strip protection outlet relay of the same of the transformer is in an acting stator or other electrical capacity protection (such as bus differential protection) strip outlet relay is in an acting state; the second condition is that the current of phase A, the current of phase B or the current of phase C of the side of the transformer reaches a setting value or zero-sequence current or negative-sequence current is larger than or equal to the setting value. The relay protection method has simple action principle, is high in reliability, and capable of removing dead zone faults of different sides and different voltage classes of the transformer quickly.

The invention discloses a method for locking magnetizing inrush current of a transformer, aiming at realizing the technical effect that the magnetizing inrush current and internal faults are correctly recognized. The method disclosed by the invention comprises the following steps: a microcomputer relay device calculates amplitudes of fundamental waves and secondary harmonic waves of current alternating capacity at all the sides of the transformer, converts the current at the medium -voltage side and at the low-voltage side in the transformer into current at the high-voltage side in the transformer, calculates differential secondary harmonic waves at all the sides of the transformer, judges the differential harmonic waves at all the sides of the transformer and the phase current harmonic waves of all the phases as well as the magnetizing inrush current, and recognizes the magnetizing inrush current and internal faults so as to protect the transformer. Compared with the prior art, by judging the differential harmonic waves at all the sides of the transformer, the method is used for judging phase current harmonic waves of all phases at high-medium-voltage sides of the transformer, and judging the magnetizing inrush current characteristics and the fault characteristic during no-load switching in, so that the main transformer does not act by mistake in normal no-load switching on, the fault transformer is quickly removed when faults occurs in no-load switching on, further the characteristic of quick relay protection action is ensured, simultaneously the reliability for relay protection is improved and the safety of a power grid is protected.

The invention discloses a method for protecting a low-voltage bus of an intelligent substation. The method is achieved through a bus protection device and branch protection measuring and control devices connected with the bus protection device in a cooperation mode, the bus protection device is started through steady current overflowing elements and current variable quantity elements of the active branch protection measuring and control devices, action allowing signals are sent to the bus protection device through power direction elements or the current overflowing elements of branches, and bus composite voltage blocking elements are adopted as the open condition of a bus fault. Internal and external faults of a bus region are judged by the bus protection device in the mode of combining starting signals and the action allowing signals, when the three conditions are met at the same time, the bus fault is judged, the bus protection device acts to remove the faulted bus, and a fault of a segmentation dead region and a fault of a transformer low-voltage side dead region can be judged and isolated. The bus faults with voltage classes of 35 kV and below can be removed fast and accurately, and the method can be directly applied to a digital substation or the intelligent substation.

The invention belongs to the field of marine electric power system protection, and particularly relates to a method for protecting medium-voltage direct-current power supply direct current zone distribution networks. The method solves the problem that selective protection can not be achieved through an existing protection method. According to the method, the selection protection on an annular direct current is achieved through coordinated protection of DC/AC/DC power transformation modules and direct current breakers, the short-circuit fault is accurately and rapidly removed, and meanwhile the cost pressure, such as the economy cost pressure, the size cost pressure and the weight cost pressure, caused by universal use of the direct current breakers on buses is avoided. The selective protection of low-voltage alternating-current distribution networks and low-voltage direct-current distribution networks is achieved through the coordinated protection of the transformation modules and inferior breakers, faults are limited inside a zone, the superior direct current buses are not influenced, and the power supply continuity of a marine electric power system to daily loads is remarkably improved.

A network type protection method based on closed-loop mode operation of a power network is used for a power network system which operates in a closed-loop mode. The power network system comprises multiple transformer stations and terminal units connected to the transformer stations, and is characterized in that each terminal unit comprises an intelligent controller, a breaker and a communication module, the communication module in each terminal unit is only communicated with the closest terminal unit, and the intelligent controller in each terminal unit collects the information of voltage, current, power direction, associative direction and state and the after-fault information of the breakers in the terminal unit and the adjacent terminal unit. According to the method, a peer-to-peer communication network is adopted, the terminal units on a circuit are communicated with one another, fault information of adjacent switches is collected, arbitrating is performed, and rapid positioning and isolating of a fault are realized.

The invention discloses a current differential protecting method of a wind electricity direct current microgrid under direct current bipolar short circuit failure. When a differential current is larger than a set value, it is judged that the failure occurs, breakers at the two ends of an electric transmission line under protection are controlled to be switched off, and meanwhile an absorption circuit is switched on. By means of the method, the faulty line can be switched off rapidly in a millisecond, and a fault current is prevented from reaching an overcurrent value on account of low impedance of a system at a fast speed, so that the whole system is prevented from breakdown. When the current differential protection loses efficacy, under voltage protection serves as a second defensive line, the circuit and power electronic components such as a diode are prevented from being damaged by a large short circuit current, and the safe operation of the system is guaranteed.

The invention relates to a pre-charged high speed direct current breaker and a control method therefor. The pre-charged high speed direct current breaker comprises a parallel cut-off branch and a main electronic switch branch, wherein the main electronic switch branch is used for circulating the current in normal operation; the cut-off branch comprises a serial cut-off switch and a capacitor, and the two ends of the capacitor are used for being connected with a charging power supply; the main electronic switch branch comprises at least one electronic switch unit, the multiple electronic switch units are connected in series, and each of the electronic switch units is composed of a high power switch apparatus. Both the cut-off switch and the main electronic switch branch are solid switches, so that the problem on use of a mechanical switch in the prior art can be avoided. The breaker simple in topological structure and control process and is convenient to realize in practical engineering.

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

The invention discloses a transient directional protection method for an AC line of a high-voltage AC/DC compound system. The transient directional protection method specifically comprises the following steps of detecting electric signals at two ends of the protected AC line through current transformers at two ends of the line of the compound system separately; preprocessing the detected electricsignals to obtain current break variables at two ends of the protected AC line, switching sampling of a protection system into a high data acquisition frequency and extracting corresponding voltage and current according to the width of a data window; calculating a front travelling wave and back travelling wave total of the current; calculating wavelet coefficients; adaptively eliminating interference values of the obtained wavelet coefficients and obtaining a synchronously extruded wavelet coefficient through extrusion processing of the wavelet coefficients, wherein the synchronously extrudedwavelet coefficient represents the energy of a transient current wave; calculating the transient energy ratio of the front travelling wave to a back travelling wave of the current; and comparing the sizes of the energy ratio and a setting value to distinguish an internal fault from an external fault. According to the transient directional protection method, the AC line of the high-voltage AC/DC compound system is provided with relay protection.

The embodiment of the invention discloses a micro-grid load reducing method. The method comprises the following steps: monitoring the grid frequency of a micro-grid; receiving operation parameters ofthe grid sent by an intelligent monitoring terminal; when the frequency of the grid decreases to a set frequency value, obtaining an active power shortage according to the operation parameter of the grid; according to the active power shortage and the priority order of shedding load, determining a load to be removed; and transmitting a load shedding instruction for the load to be removed to the intelligent monitoring terminal. The embodiment of the invention also discloses a micro-grid load reducing device and system and a storage medium.

The invention discloses a medium-voltage power grid neutral point arc suppression coil and resistor combined grounding method. On the basis of a mode that a neutral point is grounded in a resonance way through an arc suppression coil, a median resistor and a small resistor with different resistance values are connected in parallel to the arc suppression coil, and the connection and disconnection of the median resistor and the small resistor are controlled by a switch connected with a controller, so that the mutual switching among different neutral point grounding modes is achieved in the following mode. According to the invention, a neutral point grounding mode of automatically tracking the combination of the arc suppression coil system and the grounding resistor is adopted, so that transient faults and permanent faults are distinguished while overvoltage is limited, and the grounding line selection of the permanent faults is achieved, namely the advantages of suppressing overvoltage by the middle resistor, reducing the grounding current of the fault point and extinguishing arc of the arc suppression coil are fully exerted, the grounding mode of the small resistor having the good relay protection selectivity is adopted to rapidly cut off the permanent earth fault so as to improve the power supply reliability, safety and economical efficiency.

The invention discloses a device and a method for demand control of a two-way power supply system. A power flow regulator composed of an isolation transformer, a series-side inverter and a parallel-side inverter is connected in parallel to a spare power automatic switching bus tie switch between two power supply buses powered by a two-way power supply. When the sum of real-time demands of the twopaths in the two-way power supply exceeds a total demand limit value, the power flow regulator transfers the energy of one power supply bus to the other power supply bus. Thus, the sum of the total demand of the system, namely, the demand of a user metering point, is reduced, the basic electric charge is reduced, and the electric energy demand of the load can be ensured to be met. Various problemsfaced by other demand controllers in the current market can be solved, for example, the load stability is affected due to the fact that the demand is reduced by reducing the load power. The control difficulty and the equipment maintenance amount are reduced, the service life of the equipment is prolonged, and the economic benefit is very good.

The invention discloses a removing method and a control apparatus for alternating current filters for high-voltage direct-current power transmission. A constant value of the total number of the alternating current filters which need to be removed is set according to requirements of alternating current voltage and reactive power; the input alternating current filters are divided into two conditions, including the alternating current filters which participate in the filtering function and the alternating current filters which do not participate in the filtering function; the number of groups of the various kinds of equivalent removing filters of the alternating current filters which participate in the filtering function is determined according to the minimum filter configuration table; if the number of the groups of the alternating current filters which do not participate in the filtering function is greater than or equal to the constant value of the total number of the alternating current filters which need to be removed, only the alternating current filters which do not participate in the filtering function are removed; or otherwise, the alternating current filters which do not participate in the filtering function, and the alternating current filters which participate in the filtering function in the residual groups are removed; when the alternating current filters which participate in the filtering function are removed, the number of the removing groups of each type is calculated according to the filtering performance; the alternating current filters are removed in sequence rapidly; and therefore, the overvoltage of the alternating current power grid can be effectively restrained, or the reactive power requirement can be rapidly satisfied.

The invention provides a power quality regulator for a series direct current power system. The power quality regulator comprises a bidirectional direct current/direct current (DC/DC) converter, a direct current energy storage unit, a filtering unit, a voltage and current signal acquisition unit and a controller, wherein the voltage and current signal acquisition unit is connected with the controller which is connected with the bidirectional DC/DC converter and the energy storage unit respectively; and the bidirectional DC/DC converter is connected with the filtering unit and the energy storage unit respectively. A switching device of the bidirectional DC/DC converter is controlled by the controller to be turned on and off to regulate direct current electric energy output by the direct current energy storage unit into proper compensation voltage for output to the direct current power system or to transmit the redundant direct current electric energy of the direct current power system to the energy storage unit, so that the bus voltage of the direct current power system is stabilized and smoothened, maximum passing current of a series loop is controlled, and the loop is quickly switched off under a short-current failure condition to fulfill the aim of regulating the power quality of the direct current power system.

The invention discloses an isolated direct current converter applicable for a medium-voltage direct current system and a control method thereof. The direct current converter is of a modularized combined structure for a plurality of power modules through serial connection during input and parallel connection during output, and each power module consists of a switching circuit and an isolated switching circuit cascade connection. Each switching circuit consists of a switching switch, a switching power device and a short circuit prevention diode, and is used for controlling the switching and elimination of the corresponding control module, so that redundant operation and rapid fault isolation of the system are realized; when an external fault appears, the fault can be quickly eliminated, andwhen an internal fault of the module appears, the fault module can be quickly eliminated, so that normal operation of the converter is guaranteed; simultaneously, input and output voltage matching ofeach module can be guaranteed, so that the stress of voltage and current on the power device is reduced; and after the fault is eliminated, the converter also can be quickly used. The converter disclosed by the invention is high in reliability and long in service life, and is applicable for the applications such as long-distance underwater electric energy supply, interconnection of direct currentmicrogrids with different voltage levels and electrolytic aluminum and sea water desalination industries.

The invention relates to a method of fault isolation and self-healing for an electric distribution network. The method comprises the following steps: 1) non-path protection which is capable of detecting and removing any position and does not need path relation is adopted on the electric distribution network; 2) a circuit breaker capable of cutting off short circuit electricity is adopted to replace the existing load switch; and 3) a spare power supply automatic input unit is arranged on the electric network. Compared with the prior art, the method provided by the invention does not only rely on a communication channel, can be used for removing a fault section selectively and rapidly, but also the power supply at a non-fault section can be recovered rapidly, and the power distribution network has a fault self-healing capability.

The invention discloses a high-voltage direct-current breaker based on Buck-Boost converter topology and a fault removal method thereof. The purpose is to solve the problems that existing breaker equipment is high in cost, low in response speed and high in operation loss. The high-voltage direct-current breaker comprises a breaker body and a control system. The control system comprises inner loop adjusting and controlling current and outer loop adjusting and controlling voltage, an auxiliary controller is additionally arranged for double-closed-loop adjusting and used for performing voltage transforming and protection controlling on the high-voltage direct-current breaker, and therefore the high-voltage direct-current breaker has the advantages of achieving more functions, being higher in on-off speed and lowering the cost better compared with a traditional high-voltage breaker. The high-voltage direct-current breaker can achieve the functions of increasing and decreasing the voltage when a high-voltage direct-current power transmission system normally operates, can achieve switching between the voltage-increasing state and the voltage-decreasing state and can be flexibly applied to power lines of different voltage grades. Meanwhile, when happening on the power transmission lines, short-circuiting faults can be effectively removed in time.

The present invention relates to a substation area backup protection method used for simplifying transformer in-place backup protection. The conventional transformer backup protection has the difficulties of complex configuration, difficult setting and cooperation, long action delay, and poor sensitivity. The substation area backup protection method is characterized in that distance protection with forward/reverse direction acting characteristics can be configured for a breaker at each side of a transformer, impedance constant values are set according to sensitivity requirement achieving respective function, and selectivity is achieved through fixed time constant values; after that, a substation area backup protection criterion having fault tolerance is constructed according to switching quantity information within the range of the substation, so as to achieve judgment for fault components and decision for breaker tripping, thereby accelerating fault clearing within the substation. The substation area backup protection method reduces setting difficulty of transformer in-place backup protection, and achieves coordination and unification among action selectivity, quickness, sensitivity and reliability of backup protection when a fault occurs on substation equipment.