Background
The 6-35kV medium-voltage system in China mainly adopts a non-effective grounding mode that a neutral point is not grounded or is grounded through an arc suppression coil, the grounding current of a low-current grounding system is very small when a single-phase grounding fault occurs, line voltages among three phases are still symmetrical, a protection device cannot trip in action, and the operation mode allows the system to operate with the fault for 2 hours when the single-phase grounding occurs, so that the power supply reliability is greatly improved. However, with the development of urban and rural power networks and the increase of cable outgoing lines, the system has the advantages that the earth capacitance current is sharply increased, the current flowing through a fault point after single-phase grounding is large, electric arcs are not easy to extinguish, intermittent arc grounding overvoltage is easy to generate, and the weak insulation position of power network equipment is subjected to discharge breakdown and equipment is damaged instantly. Therefore, when a single-phase earth fault occurs in a low-current grounding system, arc extinction and harmonic elimination are carried out, a fault line is accurately and timely detected and directly and automatically removed, or the fault line is manually and remotely removed through alarming, and the method has very important practical significance for improving the power supply reliability, realizing the automation of a transformer substation, and improving the quality of power supply and the automation level of a power grid.
The low-current line selection mode widely used in the market at present is often influenced by various factors such as large impedance variation range of the grounding point, complex working conditions, weak zero-sequence current signals, strong electromagnetic interference and the like, the branch with the single-phase grounding fault is difficult to be quickly and accurately selected, and the line selection accuracy is low. Common single-phase earth fault processing methods include arc suppression coil compensation method, small resistance fault line method and arc suppression cabinet method for converting arc grounding into metallic grounding method. These three fault handling methods are respectively long: the arc suppression coil is suitable for an overhead line, the inductive current is used for compensating the capacitive current of the grounding point to enable the current of the fault point to be less than 5A, the system can be operated for 2 hours in a charged mode, the high-frequency current of the grounding point of the cable line cannot be compensated, and the compensation is easy to fail; the small resistor and relay protection are matched with a fault line tripping method, so that a fault line can be accurately cut, and a transient grounding fault is also cut, so that the power supply reliability is low, and the method is not suitable for enterprises; the arc suppression cabinet converts the arc grounding into the metallic grounding method to well control the arc, but the conventional line selection method cannot select a fault line after the fault point is transferred.
SUMMERY OF THE UTILITY MODEL
Technical problem to be solved
The not enough to prior art, the utility model provides a novel ground protection is synthesized in differential selection line device possesses the advantage that the practicality is good, has solved the problem mentioned in the above-mentioned background art.
(II) technical scheme
In order to achieve the above object, the utility model provides a following technical scheme: a novel differential line selection comprehensive grounding protection device comprises a high-voltage isolating switch QS, a three-phase combined high-capacity overvoltage protector TBP, a PT high-voltage fuse RD, an anti-saturation voltage transformer TV, single-phase vacuum contactors ZJa, ZJb and ZJc, a single-phase vacuum contactor ZJd, a special resistor R, a single-phase eddy current driving quick circuit breaker ARS, a zero-sequence current transformer LH and a comprehensive grounding protection device microcomputer controller ZK, wherein the upper end of the high-voltage isolating switch QS is electrically connected with a bus, the lower end of the high-voltage isolating switch QS is electrically connected with the upper end of the three-phase combined high-capacity overvoltage protector TBP, the lower end of the high-voltage isolating switch QS is electrically connected with the upper end of the PT high-voltage fuse RD, the lower end of the PT high-voltage fuse RD is electrically connected with the upper end of the anti-saturation voltage transformer TV, The upper ends of the ZJb and the ZJc are electrically connected, the lower ends of the single-phase vacuum contactors ZJa, ZJb and ZJc are electrically connected with the upper end of a special resistor R, the lower ends of the single-phase vacuum contactors ZJa, ZJb and ZJc are electrically connected with the upper end of a single-phase vacuum contactor ZJd, the lower end of a single-phase vacuum contactor ZJd is electrically connected with one end of a comprehensive grounding protection device microcomputer controller ZK, the lower end of the special resistor R is electrically connected with the upper end of a single-phase eddy current driving quick breaker ARS, the lower end of the single-phase eddy current driving quick breaker ARS is electrically connected with the upper end of a zero sequence current transformer LH, and the lower end of the single-phase eddy current driving quick breaker ARS is electrically connected with one.
Preferably, the lower end of the high-voltage isolating switch QS is grounded through a three-phase combined high-capacity overvoltage protector TBP, and the special resistor R is an electrical element with the same efficacy as a capacitor element and an inductor element.
Preferably, the switching-off time of the single-phase eddy current driving rapid breaker ARS is less than or equal to 5ms, and the switching-on time of the single-phase eddy current driving rapid breaker ARS is less than or equal to 20 ms.
Preferably, the single-phase eddy current driven fast breaker ARS is an electrical component having the same functions as a fuse, a thyristor, and the like.
Preferably, the single-phase vacuum contactors ZJa, ZJb, ZJc and ZJd are electric elements having the same functions as a circuit breaker, a switch, etc., a lower end of the single-phase vacuum contactor ZJd is electrically connected to an upper end of the single-phase eddy current driven fast breaker ARS, and a lower end of the single-phase eddy current driven fast breaker ARS is grounded through a zero sequence current transformer LH.
(III) advantageous effects
Compared with the prior art, the utility model provides a novel differential selection line integrated ground protection device possesses following beneficial effect:
1. this novel ground protection is synthesized to differential select line device, through single-phase vacuum contactor ZJa, ZJb, ZJc and purpose-built resistance R component can increase the fault point electric current in short-term, the fault line is elected to the accuracy, and can turn arc light ground connection into metal ground connection, can effectively eliminate arc light ground connection overvoltage, avoid single-phase connection arc light to arouse double-phase ground connection short circuit accident, the electrical equipment damage accident of avoiding arc light ground connection overvoltage to arouse, improve the reliability of power supply, adopt the operation safety of single-phase eddy current drive quick circuit breaker ARS as the whole equipment that back-up protection guaranteed, system safety has been protected.
2. The novel differential line selection comprehensive grounding protection device controls the switching on and off of the single-phase vacuum contactors ZJa, ZJb and ZJc through the comprehensive grounding protection device microcomputer controller ZK, utilizes the rapid and accurate switching-in of the single-phase vacuum contactors ZJa, ZJb and ZJc to quit the purpose-made resistor R, utilizes the instantaneous increase of fault point current to accurately select a fault line, enables the accuracy of line selection to reach 100%, adopts the comprehensive grounding protection device microcomputer controller ZK to accurately select the ground line, converts arc light grounding into stable metallic grounding through the single-phase vacuum contactors ZJa, ZJb and ZJc, transfers the fault point into the device, eliminates arc light overvoltage and protects the safety of electrical equipment.
3. This novel ground protection device is synthesized in differential selection line, the separating brake time of single-phase eddy current drive quick circuit breaker ARS is less than or equal to 5ms, the closing time is less than or equal to 20ms, utilize its quick characteristics, the circuit breaker establishes ties between ground resistance and ground, as the reserve protection, protect the safety of electrical equipment, adopt anti saturation voltage transformer TV to replace the voltage transformer in the conventional PT cabinet, can effectively restrain ferromagnetic resonance's emergence, reduce the damage of resonance to equipment, adopt purpose-made resistance R, this resistive element and quick circuit breaker cooperation restriction single-phase ground current, make the ground current in safety range and satisfy the requirement of selection line rate of accuracy.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
Referring to fig. 1, a novel differential line selection comprehensive grounding protection device comprises a high voltage isolating switch QS, a three-phase combined high-capacity overvoltage protector TBP, a PT high voltage fuse RD, an anti-saturation voltage transformer TV, a single-phase vacuum contactor ZJa, ZJb, ZJc, a single-phase vacuum contactor ZJd, a special resistor R, a single-phase eddy current driving fast circuit breaker ARS, a zero-sequence current transformer LH, and a comprehensive grounding protection device microcomputer controller ZK, wherein the upper end of the high voltage isolating switch QS is electrically connected with a bus, the lower end of the high voltage isolating switch QS is electrically connected with the upper end of the three-phase combined high-capacity overvoltage protector TBP, the lower end of the high voltage isolating switch QS is grounded through the three-phase combined high-capacity overvoltage protector P, the lower end of the high voltage isolating switch TBQS is electrically connected with the upper end of the PT high voltage fuse RD, the lower end of the PT high voltage, the anti-saturation voltage transformer TV is adopted to replace a voltage transformer in a conventional PT cabinet, ferromagnetic resonance can be effectively inhibited, and damage of resonance to equipment is reduced, the lower end of a high-voltage isolating switch QS is electrically connected with the upper ends of single-phase vacuum contactors ZJa, ZJb and ZJc, the lower ends of the single-phase vacuum contactors ZJa, ZJb and ZJc are electrically connected with the upper end of a special resistor R, the special resistor R is an electrical element with the same effect as a capacitive element and an inductive element, a special resistor R is adopted, the resistor element is matched with a quick circuit breaker to limit single-phase grounding current, the grounding current is enabled to be in a safety range and meet the requirement of line selection accuracy, the lower ends of the single-phase vacuum contactors ZJa, ZJb and ZJc are electrically connected with the upper end of a single-phase vacuum contactor ZJd, the lower end of a microcomputer vacuum contactor ZJd is electrically connected with one end of a comprehensive grounding protection, the single-phase vacuum contactors ZJa, ZJb, ZJc and ZJd are electrical elements with the same functions as a breaker and a switch, the lower end of the single-phase vacuum contactor ZJd is electrically connected with the upper end of the single-phase eddy current driving fast breaker ARS, the lower end of the single-phase eddy current driving fast breaker ARS is grounded through a zero sequence current transformer LH, after a grounding circuit is accurately selected through a microcomputer controller ZK of a comprehensive grounding protection device, arc grounding is converted into stable grounding metal through the single-phase vacuum contactors ZJa, ZJb and ZJc, a fault point is transferred into the device, arc overvoltage is eliminated, the safety of electrical equipment is protected, the lower end of the special resistor R is electrically connected with the upper end of the single-phase eddy current driving fast breaker ARS, the single-phase eddy current driving fast breaker ARS is an electrical element with the same functions as a fuse and a silicon controlled rectifier, the switching-off time of the single-phase eddy current driving quick breaker ARS is less than or equal to 5ms, the switching-on time of the single-phase eddy current driving quick breaker ARS is less than or equal to 20ms, the circuit breaker is connected between the ground resistance and the ground in series by utilizing the quick characteristic of the circuit breaker, the circuit breaker serves as backup protection to protect the safety of electrical equipment, the lower end of the single-phase eddy current driving quick breaker ARS is electrically connected with the upper end of a zero sequence current transformer LH, and the lower end of the single-phase eddy current driving quick breaker ARS is electrically connected with one end of a microcomputer controller ZK.
The electrical components presented in the document are all electrically connected with an external master controller and 220V mains, and the master controller can be a conventional known device controlled by a computer or the like.
When the system is in single-phase metallic grounding, a switching value acquisition module of a microcomputer controller ZK of the comprehensive grounding protection device acquires the voltage change of the system, calculates the grounding type and the grounding phase and then gives a non-fault phase single-phase vacuum contactor ZJa, ZJb and ZJc send out a closing command, the input time of (A phase arc grounding input B phase vacuum contactor, B phase arc grounding input C phase vacuum contactor, C phase arc grounding input A phase vacuum contactor) is 100ms, after 100ms, the comprehensive grounding protection device microcomputer controller ZK sends out a switching-off command to the closed single-phase vacuum contactors ZJa, ZJb and ZJc, the vacuum contactors are switched off, the non-fault phase is connected in series with a special resistor R through the vacuum contactor in the input process of the vacuum contactors to be grounded, resistive current is injected into a fault point, and a line selection module of the comprehensive grounding protection device microcomputer controller ZK accurately selects a fault line through calculation and analysis by sampling the current change of a feeder line cabinet zero sequence current LH mutual inductor; when the system generates transient single-phase arc grounding, an alternating current input signal acquisition module of a microcomputer controller ZK of the comprehensive grounding protection device acquires signals of three-phase voltages Ua, Ub, Uc, open triangle voltage UO and the like provided by an anti-saturation voltage transformer TV, and the signals are calculated and processed by a microcomputer processor, when the switching value acquisition module of the microcomputer controller ZK of the comprehensive grounding protection device acquires the change of the system voltage, the switching value acquisition module calculates and analyzes the grounding type and the grounding phase and then sends a command to a vacuum contactor of a fault phase to switch on the vacuum contactor of the fault phase, the system is quickly converted from unstable arc grounding into stable metallic grounding, the voltage of the fault phase is reduced to zero, the arc light of the fault point is extinguished, the microcomputer controller ZK of the comprehensive grounding protection device sends a switching-off command to the grounded vacuum contactor after time delay, and the grounded vacuum contactor is switched off, if the fault disappears after the vacuum contactor is opened, the fault is instantaneous arc grounding, and the system recovers normal operation; when the system generates intermittent single-phase arc grounding, a switching value acquisition module of a microcomputer controller ZK of the comprehensive grounding protection device sends a closing command to single-phase vacuum contactors ZJa, ZJb and ZJc of a non-fault phase after calculating and analyzing a grounding type and a grounding phase when acquiring the voltage change of the system, the input time of a vacuum contactor of a B phase, a vacuum contactor of a C phase and a vacuum contactor of a C phase which are respectively input by the arc grounding of the B phase and the arc grounding of the C phase after being input by the arc grounding of the C phase is 100ms, the microcomputer controller ZK of the comprehensive grounding protection device sends a closing command to the single-phase vacuum contactors ZJa, ZJb and ZJc of the vacuum contactor after 100ms, the vacuum contactor opens, the non-fault phase is grounded in series connection with a special resistor R through the vacuum contactor in the input process, resistive current is input by the fault point, a line selection module of the microcomputer controller ZK of the comprehensive grounding protection device changes the current, the fault line is accurately selected through calculation and analysis, after the non-fault phase vacuum contactor is switched off, the comprehensive grounding protection device microcomputer controller ZK sends a switching-on command to the single-phase vacuum contactor ZJd and the fault phase single-phase vacuum contactors ZJa, ZJb and ZJc, the single-phase vacuum contactor ZJd and the fault phase single-phase vacuum contactors ZJa, ZJb and ZJc send a switching-on command, so that the system is quickly converted from unstable arc grounding to stable metallic grounding, the voltage of the fault phase is reduced to zero, the arc light of a fault point is extinguished, the comprehensive grounding protection device microcomputer controller ZK sends the fault to a background through communication, a substation operator can see a grounding signal, a grounding fault phase and a grounded fault line on the background computer, and simultaneously, a liquid crystal display screen on a local comprehensive grounding protection device microcomputer controller ZK also displays grounding fault phase and grounding fault lines.
To sum up, this novel ground protection device is synthesized in differential select line can increase the fault point electric current in short-term through single-phase vacuum contactor ZJa, ZJb, ZJc and purpose-made resistance R component, the accurate fault circuit of electing, and can turn arc light ground connection into metal ground connection, can effectively eliminate arc light ground connection overvoltage, avoid single-phase connection arc light to arouse double-phase ground connection short circuit accident, the electrical equipment damage accident that avoids arc light ground connection overvoltage to arouse improves the power supply reliability, adopt the operation safety of single-phase eddy current drive quick circuit breaker ARS as the whole equipment that back-up protection guaranteed, system safety has been protected.
The novel differential line selection comprehensive grounding protection device controls the switching on and off of the single-phase vacuum contactors ZJa, ZJb and ZJc through the comprehensive grounding protection device microcomputer controller ZK, utilizes the rapid and accurate switching-in of the single-phase vacuum contactors ZJa, ZJb and ZJc to quit the purpose-made resistor R, utilizes the instantaneous increase of fault point current to accurately select a fault line, enables the accuracy of line selection to reach 100%, adopts the comprehensive grounding protection device microcomputer controller ZK to accurately select the ground line, converts arc light grounding into stable metallic grounding through the single-phase vacuum contactors ZJa, ZJb and ZJc, transfers the fault point into the device, eliminates arc light overvoltage and protects the safety of electrical equipment.
This novel ground protection device is synthesized in differential selection line, the separating brake time of single-phase eddy current drive quick circuit breaker ARS is less than or equal to 5ms, the closing time is less than or equal to 20ms, utilize its quick characteristics, the circuit breaker establishes ties between ground resistance and ground, as the reserve protection, protect the safety of electrical equipment, adopt anti saturation voltage transformer TV to replace the voltage transformer in the conventional PT cabinet, can effectively restrain ferromagnetic resonance's emergence, reduce the damage of resonance to equipment, adopt purpose-made resistance R, this resistive element and quick circuit breaker cooperation restriction single-phase ground current, make the ground current in safety range and satisfy the requirement of selection line rate of accuracy.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.