CN104821559A - Neutral point joint grounding equipment self-protection method - Google Patents
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Abstract
The present invention discloses a neutral point joint grounding equipment self-protection method. According to the method, a special frequency injection method is used to monitor whether a power grid has a grounding fault or not in real time, and when the power grid has a grounding fault, a controller controls a grounding transformer to be connected to a short-term controllable reactor to compensate a power grid. The controller judges whether the grounding fault is released in a limit time, if so, the grounding fault is judged as a grounding fault, the controller controls the short-term controllable reactor to quit compensation, and if not, the grounding fault is judged as a permanent fault, and the controller controls a contactor to be in a closed state. One end of a controlled small resistor is grounded, and the other end is connected to a contactor. The controller controls the short-term controllable reactor to quit compensation when the permanent grounding fault is ended and controls the contactor to be in a disconnection state. The neutral point joint grounding equipment self-protection method provided by the invention has the advantages of automatic switching, high safety and high reliability.
Description
Technical field
The present invention relates to technical field of power systems, particularly relate to a kind of neutral point joint grounding equipment self-protection method.
Background technology
Along with the development of electrical network, the capacity of electrical network is increasing, more and more higher to the reliability requirement of electrical network, propose requirements at the higher level to intellectuality.Power distribution network is sent out as electric power system, defeated, join and a link in electricity consumption, play a part to form a connecting link, its importance more and more comes into one's own, and the process of distribution net work earthing fault is the significant problem perplexing vast operation of power networks personnel always.Traditional earthing mode exposes increasing drawback, in the urgent need to seeking a kind of more perfect novel grounded mode on existing basis, to adapt to the development need of distribution automation, solves the control ability of electrical network in earth fault process.
Electric power system can be divided into heavy current grounding system (comprising direct ground connection, reactance grounded and low-impedance earthed system etc.), small current neutral grounding system (comprise high resistance ground, short-time controllable reactor ground connection and earth-free etc.) by grounding mode.For guaranteeing accurate isolated fault circuit, a lot of city all starts the operational mode adopting neutral point through controlled low resistance grounding.But because controlled low resistance grounding mode is non-selectivity for ground fault trip, make any instantaneity earth fault all can cause line tripping.Although recovered power transmission by these instantaneity earth faults of reclosing mode, the unnecessary electricity consumption interruption to user and the action of substation line switch repeat impact are also caused thus.The trip-out rate applying the distribution network system of controlled low resistance grounding mode is high, power supply reliability is poor, can not meet the demand of user to power supply reliability increasingly stringent.
In recent years, various places electric company has progressively built distribution automation system, plays a positive role to raising power distribution network operation and management level.The quick position isolation realizing fault is a Core Feature of distribution automation, but in the system of existing short-time controllable reactor ground connection, upon the occurrence of a ground fault, although obtain the compensation of short-time controllable reactor, but automatic intelligent terminal is difficult to accurate localizing faults, thus cannot realize the function of its automatic separating fault, therefore the effectiveness of distribution automation is had a greatly reduced quality.
In the process of construction of urban and rural power grids, China's distribution neutral ground mainly have employed resonance grounding (short-time controllable reactor ground connection) and controlled low resistance grounding pattern, wherein short-time controllable reactor earthing mode can eliminate transient single-phase earth fault automatically, there is the advantage reducing tripping operation number of times, reduce earth fault current, but it is low that controlled low resistance grounding pattern has overvoltage level, the advantages such as energy action in time.But along with the widely using of application popularization cable of distribution automation, single ground connection pattern will face following serious problems:
1. can not automatically excise non-transient single phase ground fault, whole distribution system must bear the power-frequency overvoltage (line voltage) of long period, therefore requires high to the insulation level of equipment;
2. can not automatic identification non-transient earth fault and instantaneity earth fault, and differentiated treatment in addition;
3. the long-time existence of earth fault, is unfavorable for equipment and personal safety, there is potential safety hazard;
4. cannot cooperation with distribution automation system.
Data statistics shows, at the electrical network based on cable, non-momentary fault (permanent fault) and phase fault are higher than the electrical network based on overhead wire.Tracing it to its cause is that cable body fault is less, and large multiple faults occurs in cable joint place, and permanent fault and phase fault are increased, but cable system generation ground connection might not be permanent fault or phase fault.In electrical network, cable proportion increases, and which kind of earthing mode no matter neutral point adopt, and except considering overvoltage, also should consider the problem such as short circuit current and relaying protection.
Summary of the invention
Technical problem to be solved by this invention is; a kind of neutral point joint grounding equipment self-protection method is provided; by the more perfect reliable earthing mode of one; to meet along with power distribution network capacity is increasing; the requirement more and more higher to the reliability of power distribution network; to process electric network fault in time, discriminatively, ensure that electrical network is to safety that is personal and equipment.
For solving above technical problem, the invention provides a kind of neutral point joint grounding equipment self-protection method, comprising:
Distribution network line monitoring system is set up into master station by front-end acquisition device, joint grounding device; Described front-end acquisition device comprises special source injection device, data centralization transmitter, repeater and multiple fault detector be arranged on power distribution network three-phase line frequently; Described joint grounding device comprises short-time controllable reactor, contactor, controlled small resistor and controller, and described grounding transformer is connected with electrical network bus;
Three-phase circuit voltage is detected in real time by spy's frequency source injection device; Detecting that wherein two-phase line voltage distribution raises, when third phase line voltage distribution reduces, judging earth fault occurs; After the time delay t1 time by described special source injection device frequently to circuit inject alien frequencies signal and after t2 time delay by described fault detector detection failure non-power-frequency current; Wherein, t1<t2;
After short trouble or earth fault appear in judgement, fault message and load current information are sent to master station by data centralization transmitter and repeater by described fault detector, analyze fault point by described master station;
When described electrical network generation earth fault, described controller controls described grounding transformer and accesses described short-time controllable reactor to compensate electrical network;
Described controller judges whether described earth fault is removed in limiting time; If so, then judge that described earth fault is as transient earthing fault, and described controller controls described short-time controllable reactor and exits compensation at the end of ground connection; If not, then judge that described earth fault is as permanent fault, and described controller is that closure state is to control the described controlled small resistor of described grounding transformer access by controlling described contactor; One end ground connection of described controlled small resistor, the other end is connected with described contactor;
Described controller terminates short-time controllable reactor described in time control system permanent fault ground connection and exits compensation, and is off state to exit described controlled small resistor by controlling described contactor.
Further, describedly judge whether described earth fault is removed in limiting time, is specially:
Detect the time that described short-time controllable reactor compensates electrical network;
Described short-time controllable reactor was compared the make-up time of electrical network and described limiting time; When described short-time controllable reactor exceedes described limiting time to the time that electrical network compensates, then described controller judges that described earth fault is not removed in limiting time; Otherwise described controller judges that described earth fault is removed.
Further, described controller controls described grounding transformer and accesses described short-time controllable reactor to compensate electrical network, comprising:
Described controller calculates the inductive current needing to compensate according to the current value of the electrical network electric capacity measured;
Described controller controls described short-time controllable reactor to be continued to export and the current signal of the described inductive current equivalent needing to compensate, and records the time that described short-time controllable reactor compensates electrical network.
Further, describedly specifically to be comprised by described fault detector detection failure non-power-frequency current: detect multi-group data continuously by described fault detector, using that minimum for alien frequencies value group as fault non-power-frequency current.
Further, described alien frequencies signal is the low frequency signal of particular frequencies.
Further, described fault detector is digital determining device.
Further, described data centralization transmitter comprises high pressure energy taking device, data storage and storage battery.
Further, described high pressure energy taking device is that LC series inductance formula is got and can be made device.
Further, described fire-resistant oxidation resistant resistance is grid type electric resistance of stainless sheet.
Further, described short-time controllable reactor comprises: winding, secondary winding and a ghyristor circuit;
A described winding accesses power network neutral point as Working winding, and described secondary winding is connected with described ghyristor circuit as controlled winding
The neutral point joint grounding equipment self-protection method that the embodiment of the present invention provides, crosses the method intelligent decision earth fault of special injection and detection line change in voltage frequently; Information on load and fault message beam back master station, realize information on load information, the fault information acquisition of distribution; By master station to load current information and fault information analysis, obtain the position of fault point; Realize the conbined usage of short-time controllable reactor and controlled small resistor, and apply the automatic switchover of Based Intelligent Control logic realization, duration is continued to ground connection and judges, distinguish instant earthing fault and permanent earth fault.Different counter-measures is taked for these two kinds of earth faults, both the accurately isolation rapidly to permanent earth fault had been ensured, system power frequency overvoltage long-term existence is avoided to cause accident to expand further, can carry out fine compensation to instantaneity earth fault again makes it die away, avoid repeatedly tripping, improve the safety and reliability of earth fault processing procedure.
Accompanying drawing explanation
Fig. 1 is the structural representation of a kind of distribution network line monitoring system provided by the invention;
Fig. 2 is the schematic flow sheet of an embodiment of the neutral point joint grounding equipment self-protection method that the system based on Fig. 1 provided by the invention realizes;
Fig. 3 is the one-phase earthing failure in electric distribution network line map that the embodiment of the present invention provides;
Fig. 4 is a kind of structural representation of the short-time controllable reactor that the embodiment of the present invention provides;
Fig. 5 is the equivalent circuit diagram of the short-time controllable reactor that Fig. 4 of the present invention provides.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described.
See Fig. 1, it is the structural representation of a kind of distribution network line monitoring system provided by the invention.
In the present embodiment, described distribution network line monitoring system, comprising: front-end acquisition device 100, joint grounding device 200 and master station 300.
Wherein, described front-end acquisition device 100 comprises data centralization transmitter 101, repeater 102, special source injection device 103 and multiple fault detector (fault detector of 1 ~ No. 15 as shown in Figure 1) be arranged on power distribution network three-phase line frequently.
Described joint grounding device 200 comprises short-time controllable reactor 201, controlled small resistor 202, contactor 203, controller 204 and one or more grounding transformer (three grounding transformers have been shown in Fig. 1, are grounding transformer 205, grounding transformer 206, grounding transformer 207 respectively); Described grounding transformer is connected with described contactor 203, and described controlled small resistor 202 is switched by the break-make of described contactor 203, access or disconnection power distribution network three-phase line A, B, C; Described contactor 203 is connected with described controller 204 respectively with described short-time controllable reactor 201; Described short-time controllable reactor 201 is also connected with described grounding transformer 205 ~ 207.
Further, both are integrated into a hardware unit, are convenient to the reception to power distribution network data and transmission by described data centralization transmitter 101 and the integrated device of described repeater 102.
Described data centralization transmitter 101 comprises high pressure energy taking device 11, data storage 12 and storage battery 13.
Adopt high pressure energy taking device 11 and storage battery 13 associating power supply mode, can the lasting unremitting normal work of effective guarantee data centralization transmitter 101.Wherein, described high pressure energy taking device 11 is preferably LC (inductance/capacitance) series inductance formula and gets and can make device, and described LC series inductance formula is got and device can be made also to comprise stand-by power supply; Described stand-by power supply is disposable high-capacity lithium battery.Data centralization transmitter 101 is got by LC series inductance formula and device can be made can to power by direct induction energy fetching from distribution network line, and storage battery 13 can as stand-by power supply, when distribution network line break down and power-off time can enable.The advantages such as LC series inductance formula is got can make device have not by weather effect, do not affect by line load size, the little cost of volume is low, and there is voltage measurement function, whole energy taking device safety, reliable, maintenance-free.
Data storage 12 can be preferably DataLog database, can at the DBMS and minute DBMS of more than year second of local cache more than one month.When communication abnormality, data are stored in local data memory 12 and do not lose, and after monitoring communication recovery, progressively transmit data stage by stage, ensure that the high reliability of communication and data.
Described repeater 102 is communicated to connect by radio-frequency device and described fault detector, and is communicated to connect by mobile communication transceiver end P and described master station 300.
Data centralization transmitter 101 and repeater 102 can be integrated into the repeater in broad sense, both can be communicated to connect by RF (radio frequency) mode with the fault detector of front end, the mode of mobile public network can be adopted to communicate to connect with the master station 300 on backstage again, volume is little, lightweight, easy to loading and unloading.
The Main Function of the master station 300 on backstage is data acquisition, Monitor and Control.The line load that master station 300 is transmitted by receiving front-end collector, voltage; the location data such as single phase ground fault, phase fault section; and control command can be sent read instant data, remote control of circuit breaker deciliter, remotely modifying protection definite value, front-end acquisition device parameter.
Master station 300 can independently be installed on distribution scheduling center, also combines with original major network dispatching patcher by standard communication protocol, and adds man-machine interface, and dispatcher can grasp power distribution network ruuning situation by man-machine interface comprehensively.
As shown in Figure 2, it is the schematic flow sheet of an embodiment of the neutral point joint grounding equipment self-protection method that the system based on Fig. 1 provided by the invention realizes, and comprises the steps:
S1: detect three-phase circuit voltage in real time by spy's frequency source injection device;
S2: detecting that wherein two-phase line voltage distribution raises, when third phase line voltage distribution reduces, judging earth fault occurs;
S3: after the time delay t1 time by described special source injection device frequently to circuit inject alien frequencies signal and after t2 time delay by described fault detector detection failure non-power-frequency current; Wherein, t1<t2;
S4: after short trouble or earth fault appear in judgement, fault message and load current information are sent to master station by data centralization transmitter and repeater by described fault detector, analyze fault point by described master station;
S5: when described electrical network generation earth fault, described controller 204 controls described grounding transformer and accesses described short-time controllable reactor 201 to compensate electrical network;
S6: described controller 204 judges whether described earth fault is removed in limiting time; If so, then judge that described earth fault is as transient earthing fault, and perform step S9; If not, then judge that described earth fault is as permanent fault, and perform step S7;
S7: described controller 204 accesses described controlled small resistor 202 for closure state to control described grounding transformer 101 by controlling described contactor 203; One end ground connection of described controlled small resistor 202, the other end is connected with described contactor 203; And perform step S8;
S8: described controller 204 is off state to exit described controlled small resistor 202 by controlling described contactor 203 at the end of permanent fault ground connection; And perform step S9;
S9: described controller 204 controls described short-time controllable reactor 201 and exits compensation at the end of ground connection.
Particularly, in step s3, multi-group data is detected continuously by described fault detector, using that minimum for alien frequencies value group as fault non-power-frequency current.
Particularly, describedly judge whether described earth fault is removed in limiting time, is specially:
Detect the time that described short-time controllable reactor compensates electrical network;
Described short-time controllable reactor was compared the make-up time of electrical network and described limiting time; When described short-time controllable reactor exceedes described limiting time to the time that electrical network compensates, then described controller judges that described earth fault is not removed in limiting time; Otherwise described controller judges that described earth fault is removed.
Particularly, described controller controls described grounding transformer and accesses described short-time controllable reactor to compensate electrical network, comprising:
Described controller calculates the inductive current needing to compensate according to the current value of the electrical network electric capacity measured;
Described controller controls described short-time controllable reactor to be continued to export and the current signal of the described inductive current equivalent needing to compensate, and records the time that described short-time controllable reactor compensates electrical network.
Referring to Fig. 3, it is the one-phase earthing failure in electric distribution network line map that the embodiment of the present invention provides.
Raise when spy's frequency source injection device 400 detects two-phase line voltage distribution, when another phase circuit voltage drop is low, think circuit generation single-phase earthing, signal generation apparatus is utilized to inject 220Hz alien frequencies signal to circuit after time delay certain hour (as 3.5 to 4 minutes), this alien frequencies signal is the low frequency signal (adopting low frequency signal mainly in order to reduce the decay of line distribution capacitance to this detection signal) of a particular frequencies, data centralization and transmission unit also can detect that voltage changes simultaneously, time delay another time (as 4 to 4.5 minutes) backward fault detector sends and detects alien frequencies signal command, fault detector to detect continuously after many groups of (as 5 groups) data then using that minimum for alien frequencies value group as fault non-power-frequency current, be sent to data centralization transmitter 100.Alien frequencies signal can be exported examine a line fault again by the special source injection device 400 frequently of mandatory order after earth fault has a power failure.
As shown in Figure 3, if there is earth fault, special after source injection device 400 injects alien frequencies frequently, then the non-power-frequency current that 3,6, No. 9 fault detectors detect forms fault loop; And the fault data detecting acquisition judges fault point after carrying out intellectual analysis by master station 300 pairs of fault datas after beaming back master station 300.
When detecting that power distribution network breaks down, also need the type of failure judgement, and choose corresponding earthing mode according to the type of fault and eliminate electric network fault.
Known through putting into practice, although single grounding through arc mode can eliminate transient single-phase earth fault automatically, there is the advantage reducing tripping operation number of times, reduce earth fault current, but also exist significantly not enough, be mainly manifested in: the failure line selection of (1) arc suppression coil earthing system, it is a technical barrier always, actual route selection accuracy rate is not high, scheduling and operations staff have to take old-fashioned " open line method " to find out ground path, waste time and energy, efficiency is low, influential system safety.(2) needs of distribution automation development are not suitable with.When there is single phase ground fault, due to the compensation of arc suppression coil, ground connection zero-sequence current is very little, zero sequence power direction is uncertain, make the intelligent terminal of automation be difficult to accurate route selection and location, cannot realize the function of its automatic separating fault, the effectiveness of distribution automation is had a greatly reduced quality.Therefore, the embodiment of the present invention is improved fault earthing mode.
As shown in Figure 1, when breaking down, joint grounding device 200 can carry out ground connection by short-time controllable reactor 201 and controllable resistor 202 two kinds of modes.
Wherein, described controllable resistor 201 is preferably fire-resistant oxidation resistant resistance.Further, described fire-resistant oxidation resistant resistance can more preferably grid type electric resistance of stainless sheet.One end ground connection of described controllable resistor 202, the other end is connected with described circuit breaker 203, realizes dropping into electrical network to described controllable resistor 202 or excising from electrical network by the switching over of described circuit breaker 203.Grid type design and the resistor disc mode of cutting out optimized make controllable resistor 202 have broad area of dissipation, and temperature rise is low; Resistor disc non-oxidizability is strong, and fusing point, higher than 1450 DEG C, can be used in the torrid zone and more filthy environment; Grid type resistor disc has excellent temperature coefficient, both ensure that the sensitivity of protection act, again can when relay fail fault current limiting; The stainless steel material of high-quality and special effective structural design, make resistance volume little, lightweight, Each part intensity is high, can sustain swing, vibration, variations in temperature, without any distortion; And modular structural design, make change or increase a certain unit and without the need to dismantling whole equipment.
The feature of short-time controllable reactor 201 is that it allows running time very short under designing rated current, about tens of second, this design feature determines and its volume greatly can be reduced, and can design, effectively saved transformer station's floor space with the compact integrated cabinet of secondary accessory.In addition, the secondary control device of short-time controllable reactor 201 is also arranged on reactance transformer cabinet, and the cable line avoiding long distance is laid, and simplifies reliability and antijamming capability that product structure also improves product simultaneously.
See Fig. 4, it is a kind of structural representation of the short-time controllable reactor that the embodiment of the present invention provides.
Wherein, short-time controllable reactor 201 comprises winding (x1, o1), secondary winding (x2, o2) and a ghyristor circuit; Described ghyristor circuit preferably includes two oppositely and the thyristor D1 connect, thyristor D2.A described winding (x1, o1) accesses described neutral point of electric network as Working winding, and described secondary winding (x2, o2) is connected with described ghyristor circuit as controlled winding.
Referring to Fig. 5, it is the equivalent circuit diagram of the short-time controllable reactor that Fig. 4 of the present invention provides.
The tracing compensation monitoring principle of short-time controllable reactor 201 is: real-time tracking power distribution network, when power-to-ground capacitance change, namely, when winding coil detects that grounding transformer neutral point voltage has a change of Δ U (Δ U<1V), system measures power distribution network capacitance to earth at that time within the short time (as 1 second).Then when there is Single Phase Metal ground connection, the capacitance current flow through is by neutral point:
Wherein,
the offset current of neutral point when there is single phase ground fault,
it is the vector value of the neutral point voltage in different induction situation; Xk is the equivalent impedance of winding coil.The angle of flow of two thyristors in ghyristor circuit is controlled by controller, regulates the silicon controlled angle of flow by change between 0 to 180 degree, silicon controlled equiva lent impedance R is changed by between ∞ to 0, then the offset current exported by controller 204
just can at 0 to rated value
between obtain continuous stepless regulate (electric current, without differential, is the basis of high-accuracy compensation).
In the present embodiment, the operation principle of joint grounding device 200 is:
When power distribution network generation earth fault, equipment calculates the inductive current needing to compensate according to the electric network capacitance and current value measured by controller 204, then controls controlled reactor and exports offset current.After general instantaneity earth fault is compensated by inductive current, arc extinction earth fault eliminates recovery normal condition automatically, thus avoids and to occur in low resistance grounding mode that one has fault to trip at once to make the situation that line tripping rate is high.Compensate rear long period (being generally set as 10s) earth fault for short-time controllable reactor 201 still to exist, then think that system there occurs permanent earth fault, generally need have a power failure process.Now processing procedure be when the ground connection duration more than 10s after automatically closed high contactor group 203 drop into controllable resistor 202, make protection for feed line action, by switch trip excision faulty line.After dropping into controllable resistor 202, short-time controllable reactor 201 exits compensation automatically, when after faulty line isolation, System recover normally runs, controller 204 control appliance automatically disconnects and exits controllable resistor 202, therefore the input of short-time controllable reactor 201 achieves accurately isolated fault circuit fast, avoids failure propagation.
Further, the contactor 203 in the present embodiment is made up of two high voltage connector parallel connections.Adopt two-way high voltage connector in parallel during concrete enforcement, and high voltage connector adopts alternating current-direct current two-way power supply as operating mechanism power supply respectively, is controlled by secondary device, which has ensured and has controlled reliability to controllable resistor 202.Preferably, described high voltage connector is vacuum contactor.
The present embodiment adopts high short-circuit impedance pressure swing type controlled short-time controllable reactor electric network fault to be processed to the advantage with following uniqueness:
One, because adopting short-circuit impedance instead of excitation impedance as working impedance, thus short-time controllable reactor 201 voltage-current characteristic can ensure to keep the splendid linearity in the 0-110% range of nominal tension;
Its two, because of adopt SCR control, thus short-time controllable reactor 201 response speed is exceedingly fast, and output current can between 0-100% rated current continuous stepless regulate; Adopt and control with mode, during normal operation, electrical network is away from resonance point, without the need to the damping resistance easily had problems;
Its three, compared with traditional short-time controllable reactor etc., the structure of the short-time controllable reactor 201 that the present embodiment provides is simple, and noise is little, is not with any rotation or transmission mechanism, without loaded switch and contactor.
The neutral point joint grounding equipment self-protection method that the embodiment of the present invention provides, crosses the method intelligent decision earth fault of special injection and detection line change in voltage frequently; Information on load and fault message beam back master station, realize information on load information, the fault information acquisition of distribution; By master station to load current information and fault information analysis, obtain the position of fault point; Realize the conbined usage of short-time controllable reactor and controlled small resistor, and apply the automatic switchover of Based Intelligent Control logic realization, duration is continued to ground connection and judges, distinguish instant earthing fault and permanent earth fault.Different counter-measures is taked for these two kinds of earth faults, both the accurately isolation rapidly to permanent earth fault had been ensured, system power frequency overvoltage long-term existence is avoided to cause accident to expand further, can carry out fine compensation to instantaneity earth fault again makes it die away, avoid repeatedly tripping, improve the safety and reliability of earth fault processing procedure.
The above is the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications are also considered as protection scope of the present invention.
Claims (10)
1. a neutral point joint grounding equipment self-protection method, is characterized in that, comprising:
Distribution network line monitoring system is set up into master station by front-end acquisition device, joint grounding device; Described front-end acquisition device comprises special source injection device, data centralization transmitter, repeater and multiple fault detector be arranged on power distribution network three-phase line frequently; Described joint grounding device comprises short-time controllable reactor, contactor, controlled small resistor and controller, and described grounding transformer is connected with electrical network bus;
Three-phase circuit voltage is detected in real time by spy's frequency source injection device; Detecting that wherein two-phase line voltage distribution raises, when third phase line voltage distribution reduces, judging earth fault occurs; After the time delay t1 time by described special source injection device frequently to circuit inject alien frequencies signal and after t2 time delay by described fault detector detection failure non-power-frequency current; Wherein, t1<t2;
After short trouble or earth fault appear in judgement, fault message and load current information are sent to master station by data centralization transmitter and repeater by described fault detector, analyze fault point by described master station;
When described electrical network generation earth fault, described controller controls described grounding transformer and accesses described short-time controllable reactor to compensate electrical network;
Described controller judges whether described earth fault is removed in limiting time; If so, then judge that described earth fault is as transient earthing fault, and described controller controls described short-time controllable reactor and exits compensation at the end of ground connection; If not, then judge that described earth fault is as permanent fault, and described controller is that closure state is to control the described controlled small resistor of described grounding transformer access by controlling described contactor; One end ground connection of described controlled small resistor, the other end is connected with described contactor;
Described controller terminates short-time controllable reactor described in time control system permanent fault ground connection and exits compensation, and is off state to exit described controlled small resistor by controlling described contactor.
2. neutral point joint grounding equipment self-protection method as claimed in claim 1, is characterized in that, describedly judges whether described earth fault is removed in limiting time, is specially:
Detect the time that described short-time controllable reactor compensates electrical network;
Described short-time controllable reactor was compared the make-up time of electrical network and described limiting time; When described short-time controllable reactor exceedes described limiting time to the time that electrical network compensates, then described controller judges that described earth fault is not removed in limiting time; Otherwise described controller judges that described earth fault is removed.
3. neutral point joint grounding equipment self-protection method as claimed in claim 2, it is characterized in that, described controller controls described grounding transformer and accesses described short-time controllable reactor to compensate electrical network, comprising:
Described controller calculates the inductive current needing to compensate according to the current value of the electrical network electric capacity measured;
Described controller controls described short-time controllable reactor to be continued to export and the current signal of the described inductive current equivalent needing to compensate, and records the time that described short-time controllable reactor compensates electrical network.
4. neutral point joint grounding equipment self-protection method as claimed in claim 1; it is characterized in that; describedly specifically to be comprised by described fault detector detection failure non-power-frequency current: detect multi-group data continuously by described fault detector, using that minimum for alien frequencies value group as fault non-power-frequency current.
5. neutral point joint grounding equipment self-protection method as claimed in claim 4, it is characterized in that, described alien frequencies signal is the low frequency signal of particular frequencies.
6. the neutral point joint grounding equipment self-protection method as described in claim arbitrary in Claims 1 to 5, it is characterized in that, described fault detector is digital determining device.
7. the neutral point joint grounding equipment self-protection method as described in claim arbitrary in Claims 1 to 5, it is characterized in that, described data centralization transmitter comprises high pressure energy taking device, data storage and storage battery.
8. neutral point joint grounding equipment self-protection method as claimed in claim 7, it is characterized in that, described high pressure energy taking device is that LC series inductance formula is got and can be made device.
9. neutral point joint grounding equipment self-protection method as claimed in claim 8, it is characterized in that, described fire-resistant oxidation resistant resistance is grid type electric resistance of stainless sheet.
10. neutral point joint grounding equipment self-protection method as claimed in claim 9, it is characterized in that, described short-time controllable reactor comprises: winding, secondary winding and a ghyristor circuit;
A described winding accesses power network neutral point as Working winding, and described secondary winding is connected with described ghyristor circuit as controlled winding.
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| CN108802557A (en) * | 2018-06-28 | 2018-11-13 | 安徽康能电气有限公司 | A kind of fault locator based on disturbing signal |
| CN110854836A (en) * | 2019-12-05 | 2020-02-28 | 国网山东省电力公司淄博供电公司 | Automatic tracking arc extinction compensation and line selection device based on public parallel resistor |
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