CN217656418U - Thunder and lightning incident releasing device - Google Patents

Abstract

The utility model discloses a thunder and lightning incident release comprises high damping resistor, inferior damping resistor, CT, grounding transformer, digital measurement and control device, circuit breaker, necessary actuating mechanism etc.. The high damping resistor and the secondary damping resistor in the lightning incident releasing device are connected in parallel, and the head end of the secondary damping resistor is provided with an open circuit and is controlled by a digital measurement and control device; the high-damping resistor is connected with a current transformer in series, and the current transformer is electrically controlled and connected with the digital measurement and control device; the lightning incident release device provides lightning current incident release conditions for power supply and distribution lines and transformer substations, reduces the probability of limited damage and insulation of lightning current release, and has various functions of preventing lightning breakdown insulation from being developed into internal overvoltage expansion accidents. The defect that the lightning arrester cannot release the strong lightning incident impact wave head is overcome, the defects that the high-frequency arc reignition cannot be inhibited by different neutral points and grounding devices, the parameters are unreasonable or the function of preventing the expansion accident is not perfect are overcome, and the power supply reliability is improved.

Description

Thunder and lightning incident releasing device

Technical Field

The utility model relates to a power supply system lightning protection and the inside overvoltage protection field of electric wire netting, concretely relates to thunder and lightning incident release.

Background

For a long time, the overhead transmission line in the environment of a strong lightning area and a multi-lightning area suffers from frequent lightning strikes to damage equipment and power failure accidents, and huge losses are caused to a power system and an enterprise power supply system. Therefore, the occurrence of lightning invasion accidents is mainly caused by the incompatibility of lightning protection technical measures with natural environment and power grid environment. Lightning has various invasion forms such as direct attack, shielding attack, induction, incident impact and counterattack, and thundercloud discharge also has a plurality of characteristics such as pre-discharge, streamer discharge and 'ball thunder' discharge. Therefore, how to solve the problem is an important issue. The technology only provides the following analysis and solution methods for the problems of incident impact of thunder and lightning, wave head superposition, evolution expansion accidents and the like: at present, lightning arresters are mainly adopted for preventing lightning induction and incident shock wave head release in a power system, and play an important role in solving low-intensity lightning induction and shock wave head problems in actual operation, but only can appropriately relieve damage to medium-intensity and high-intensity lightning induction current incident shock of 40 kA-350 kA, and lightning damage cannot be fundamentally solved. The incident caused by the incident lightning impact and the superimposed impact accounts for about 50 percent of all lightning damage accidents. The protection of the conventional power line against the incident impact of induced lightning mainly has the following three problems:

one is that the lightning arrester can not thoroughly solve the problems of inductive lightning incident impact damage and wave head superposition

The lightning incident impact refers to the phenomenon that when cloud ground discharge and discharge between two poles of thunderclouds induce a line conductor, a lightning current impact wave head moves towards two sides of a lightning induction central point to impact or lightning injected into the conductor when the conductor is struck by lightning flows towards two sides of a lightning point to impact. Its shock wave head lightning current is represented by i _L And (4) showing. When strong induction lightning or lightning strike on the wire occurs, the lightning current can be released only by the lightning arrester, the lightning arrester has a larger resistance value in megaohm level, and can only release 10 kA-20 kA, and if 150kA lightning current shock wave head occurs, about 130kA cannot be released. The shock waves at two ends can cause the problem of the back folding and superposition of shock wave heads, namely the first wave head of the incident shock is

When the impact release is limited, two wave heads are folded and superposed, and the folded and superposed wave heads are larger than

Is less than

(typically the incident impacts the first wave head

Breakdown of the insulation is possible at 20 kA). When the wave head is small, the line arrestor can release a part, thereby eliminating the lightning damage. Such as the effective discharge of lightning current in low intensity lightning environments. If the wave front is as large as 40kA, the insulation of the equipment may be broken, and if it is more than 50kA or more, the insulation must be broken. The problem is related to the cloud-ground discharge distance, the maximum value of the induced voltage and the residence time of the lightning charge on the wire, and the core isThe problem is whether the lightning current can be released in time.

Secondly, the accident of frequency division resonance overvoltage expansion easily developed when strong lightning breaks through single-phase insulation

When strong lightning breaks down single-phase insulation or insulation weak points exist in the system, the discharge process of the lightning is finished, and under the general condition, the leakage inductance L of the power transformer is obtained _S Relative earth capacitance C _O And a fault point oscillation current I _OS The influence is that the high-frequency arc reignition overvoltage which is converted into the internal overvoltage, namely the frequency division resonance overvoltage, breaks down the other phase or two-phase insulation to expand to a short-circuit accident, and simultaneously causes the instantaneous low voltage of the whole system, so that the voltage loss tripping of the electric equipment is caused, and the large-scale production stop of the whole system is caused. In actual operation, such accidents often occur. When lightning breaks down single-phase insulation, the system generates zero-crossing arc reignition overvoltage, and the oscillation frequency and the overvoltage amplitude of the zero-crossing arc reignition overvoltage are increased along with the increase of the number of arc reignition times. Namely, when the oscillation frequency of the oscillation loop formed by the inductor and the capacitor is reignited for the first time:

its overvoltage Uov = Ust + Uos

In the formula: uov is overvoltage; uos is the oscillating voltage; ust is the final regulated voltage; ls is the leakage inductance of the power transformer, the relative ground capacitance of Co and the oscillating current of the Ios fault point.

Oscillation frequency when the second re-ignition occurs:

amplitude of oscillation voltage:

where Uosm is the amplitude of the oscillating voltage Uos

Over-voltage

And in the third re-burning:

·············

at the tenth reignition:

·············

that is, when the earth arc reignites again after each half cycle, the overvoltage continues to rise until another phase or two-phase insulation is broken down, or the equipment is burned down by a multi-point fault short circuit.

Referring to fig. 1, there are various forms of resonance, such as a resonant tank consisting of an inductance element with a core, a no-load transformer, a voltage transformer, etc., and a capacitance element in a system. The inductance parameter of the iron core inductance element is nonlinear under the influence of iron core saturation, and the loop containing the nonlinear inductance element can generate ferromagnetic resonance when a certain resonance condition is met. Fig. 1 is a resonant tank consisting of a linear capacitor and a core inductor. Referring to fig. 2, since the saturation level of the core increases with the increase of the current, the inductance L gradually decreases with the increase of the current, and thus the current-voltage characteristic of the inductance in the loop is nonlinear. Curve 1 in fig. 4 is the current-voltage characteristic of the capacitance C. Curve 2 is the current-voltage characteristic of the nonlinear inductor L, i.e. at the intersection b of the two, the resonance condition is fulfilled. Curve 3 is the difference of the sums, i.e. the total voltage drop of the loop, i.e. the value of the supply voltage, which can be written as:

thirdly, the problems of limited release, expanded accidents and the like existing in the lightning impulse prevention by the neutral point grounding device

When the incident impulse lightning current is released by depending on the neutral point grounding device of the power grid, the effect difference is larger because the performance, the parameter, the structure and the function of each grounding device are different. From the problems of inappropriateness, such as device parameters, structures, functions and the like, and accident enlargement and the like of the factors of lightning release capacity, effect, whether accidents and power supply continuity can be enlarged or not after lightning stroke evolution, reliability, overvoltage amplitude, suppression level to resonance, suppression level to high-frequency and power-frequency arc light grounding overvoltage, fault burning loss degree, whether important load power supply continuity can be guaranteed, instant grounding error tripping is prevented, accuracy of grounding line selection, influence on communication, step voltage and personal safety, multipoint fault occurrence rate, whether insulation of a main transformer is damaged or not and the like, the problems are specifically as follows:

(1) Neutral point non-grounding mode and grounding mode through lightning arrester

The advantages are that:

(1) the investment is saved;

(2) the system capacitor current is small, the system harmonic is extremely small, and the single-phase grounding can continuously operate for 2 hours.

The disadvantages are as follows:

(1) the arc grounding overvoltage multiple is as high as more than 6PU, and accidents are easy to expand. The overvoltage duration is long, and the ground arcs (power frequency and high frequency) of the overvoltage duration are all in the whole network and have the problem of repeated reignition, so that the overvoltage and the oscillation frequency are continuously increased, and the insulation of equipment is damaged. Can be expanded to another phase fault or multi-point fault or even cable fire in 0.02 second

(2) Easily occurring resonance overvoltage without inhibiting measures

(3) Greatly affected by harmonic wave, no inhibiting measure, and aggravated resonance accident probability

(4) The shift voltage of the neutral point is higher and can not be inhibited by itself

(5) The release of the incident impact wave head of the lightning current is severely limited, the strong lightning induction incident impact lightning current wave head can only be released by the lightning arrester, the resistance value of the lightning arrester is megaohm, the release capacity can only be about 10-20% of the total lightning current, most of the lightning current can not be released, and the equipment damage and the power failure accidents become necessary.

The grounding mode has the advantage of investment saving, but the disadvantage of the grounding mode is fatal, and no limitation measures are provided for resonance overvoltage and arc grounding overvoltage, and only development can be carried out, so that equipment damage accidents and power failure and production halt are inevitable.

(2) Arc suppression coil grounding mode

The advantages are that:

(1) reducing the power frequency arc grounding overvoltage to below 3.2PU in a compensation capacitor current mode; compared with a mode that a neutral point is not grounded, the technology is greatly improved.

(2) When the system with extremely small harmonic current is subjected to single-phase grounding, the system can be continuously operated for 2 hours with one-point grounding, and is more suitable for a system without harmonic and operating infrequently.

The disadvantages are as follows:

(1) the high-frequency arc reignition overvoltage cannot be inhibited;

(2) the suppression effect on the resonance overvoltage is poor;

(3) the neutral point displacement voltage is easy to increase;

(4) the amplitude of the arc grounding overvoltage is 3.2 times, and the insulation fit margin is relatively low.

(5) Because the arc suppression coil is an inductive element, the arc suppression coil has a blocking effect on the release of the lightning current shock wave head, and is not beneficial to the timely release of the lightning current.

(3) Arc and resonance elimination device (fault grounding mode)

The arc and resonance extinction device (fault grounding mode) does not belong to a neutral point grounding mode, and the design concept is to reduce the transition resistance of a fault point, so that the fault phase is manually switched on and a real grounding point is manually manufactured to eliminate the reignition overvoltage of the intermittent arc.

The advantages are that:

(1) when single-phase grounding is carried out, the grounding phase is closed to prevent the occurrence of discontinuous arcs, and high-amplitude arc grounding overvoltage is prevented.

The disadvantages are that:

(1) when the system is not grounded in daily operation, the resonance overvoltage cannot be effectively inhibited, so that the resonance overvoltage breakdown insulation accidents are more;

(2) when the single-phase earth fault of the system is eliminated, the system cannot be automatically recovered, the earth fault is still not eliminated, the device needs to be repeatedly pulled and closed for verification, and the operation is complex;

(3) when the grounding phase is pulled away, arc grounding overvoltage is still generated.

(4) The lightning current incident shock wave head release has no effect, and the damage degree is the same as that of a neutral point ungrounded mode.

(4) Conventional high-value resistance grounding mode

The advantages are that:

(1) effectively suppressing the operation overvoltage;

(2) the power frequency and high-frequency arc reignition can be effectively inhibited in the initial grounding stage;

the disadvantages are as follows:

(1) when the belt is grounded and continuously operates, the sudden drop of resistivity easily occurs to cause the resistor to be fused or exploded, so that the system is changed into a neutral point ungrounded mode, and the system is placed in a dangerous high-amplitude overvoltage state;

(2) the accuracy rate of grounding line selection is relatively low, and the line selection is easily expanded into an interphase short circuit accident and causes a system power failure accident to cause large-scale production stop;

(3) the incident and release conditions of lightning current cannot be completely met due to the parameters, the structure and the functions;

(5) High damping resistance grounding mode

The advantages are that:

(1) effectively limit various forms of resonant overvoltage of the system;

after the neutral point is connected with the high damping resistor, the amplitude of the power frequency arc grounding overvoltage is effectively limited to be below 2.3PU, and various forms of resonance overvoltage in the system are comprehensively inhibited, such as broken line resonance overvoltage (operation overvoltage), frequency division resonance overvoltage of high-frequency arc restriking and the like; the system insulation breakdown accident is greatly reduced, and when the system is in single-phase grounding, the accident is not expanded.

(2) The system power-off accident is greatly reduced, and the large-scale production stop loss caused by power-off can be reduced;

(3) reducing the shift voltage of the neutral point of the system;

(4) excellent thermal stability

The resistivity tends to be stable after sudden drop in a high-temperature state, does not continuously drop, does not deviate from an effective damping interval, and has the resistance value variation not exceeding +/-2%.

(5) The method is suitable for the situation of capacity expansion and large-range change of the earth capacitance current after the system, the cost of spare parts of a neutral point grounding device is not required to be increased during capacity expansion transformation, and the resistance is not required to be adjusted; the equipment is simple and reliable, and the service life is long;

the disadvantages are as follows:

(1) the accuracy rate of grounding and line selection is less than 100 percent;

(2) the current for releasing lightning has certain conditions, but is greatly influenced by other elements, parameters, structures and functions.

(3) When the lightning protection device is used for lightning incident release, the problems of incomplete function and unreasonable parameters exist.

(6) Low value resistance grounding mode

The advantages are that:

(1) the overvoltage amplitude is relatively low;

(2) the equipment cost is relatively low.

The disadvantages are that:

(1) single-phase grounding immediately trips, and the continuity of important load power supply cannot be guaranteed;

(2) easy instantaneous grounding error tripping further affects power supply reliability

The single-phase grounding is divided into two forms of permanent grounding and instantaneous grounding, if the single-phase grounding is the permanent grounding, the zero-sequence protection action tripping belongs to normal action tripping, and therefore an obvious fault point exists in the condition; if the earth fault which can be cleared by self is instantaneous discharge, the zero sequence protection action trips, and the instantaneous earth which can be cleared by self is converted into tripping power failure, so that the abnormal action is realized. The problem is mainly related to a neutral point low resistance grounding mode, a large current of a low resistance grounding mode is connected with a small arc of instantaneous earth discharge or flashover, and enough starting current is provided for zero sequence protection, so that tripping power failure is caused. If a delay-trip method is used to discriminate whether the grounding is instantaneous grounding or permanent grounding, the high burning loss of the grounding method with low resistance and high current is abandoned, and the false tripping becomes necessary.

(3) Under the low resistance grounding mode, the high current grounding system belongs to a high current grounding system, and when the tripping time is prolonged, the burning loss of a fault point is increased;

(4) the low resistance belongs to an ineffective damping resistance or a critical secondary damping resistance, and when the system is operated in daily life, namely the system is not grounded, no inhibiting measure or poor inhibiting effect is provided for resonance generated in the system, so that the total accident rate is more than that of a high damping resistance grounding mode with effective damping;

(5) if the lightning current incident releasing device is used for lightning current incident releasing and expansion accident prevention, the lightning current incident releasing device is greatly influenced by self parameters, functions, structures and the like, and the overall effect is not ideal.

(7) Direct grounding mode

The advantages are that: the release effect on the incident impact wave head of the lightning current is good, the impact wave head can be effectively released under the general condition, and the accident that the induced lightning current is incident to impact and damage the equipment insulation is avoided.

The disadvantages are as follows:

(1) the single-phase grounding immediately trips, and the reliability and continuity of power supply are reduced.

(2) Instantaneous earth false tripping is easy to occur.

In summary, different grounding methods and grounding devices for neutral points have different advantages and disadvantages, and the neutral point direct grounding method with the best effect on solving the problem of induced lightning current surge release is the best, but the problem of accident enlargement cannot be completely solved finally because the single-phase grounding is tripped immediately and the power supply continuity is not guaranteed, and the direct grounding method is not adopted except for systems with voltage levels of 110kV and above in general.

SUMMERY OF THE UTILITY MODEL

The utility model provides a thunder and lightning incident release device, the purpose is for supplying distribution line and transformer substation to provide the lightning current incident release condition, reduces the limited damage insulation probability of lightning current release, possesses simultaneously and prevents to take place the thunder and lightning and punctures insulating each item function that evolves into inside overvoltage and enlarge the accident. The defect that the lightning arrester cannot release the strong lightning incident shock wave head is overcome and compensated, the defects that the high-frequency electric arc reignition cannot be restrained by different grounding modes of a neutral point and a grounding device, the parameters are unreasonable or the function of preventing the expansion accident is not perfect are overcome, and the power supply reliability is improved.

The utility model discloses a realize like this: a thunder incident release device comprises a high damping resistor, a secondary damping resistor, a current transformer, a grounding transformer, a digital measurement and control device and a circuit breaker, wherein the self-inductance and mutual-inductance components of the high damping resistor in the thunder incident release device are zero, so that the thunder incident release condition is met, the resonance is effectively damped, the high damping resistor and the secondary damping resistor are connected in parallel, and the head end of the secondary damping resistor is provided with an open circuit and is controlled by the digital measurement and control device; the high-damping resistor is connected with a current transformer in series, and the current transformer is electrically controlled and connected with the digital measurement and control device.

Further, the high damping resistor damping and the sub-damping resistor damping ranges are:

(1) damping range of high damping resistor at 6.3 kV: 182 Ω -900 Ω, the sub-damping resistor damping range: 18-36 omega;

(2) damping range of high damping resistor at 10.5 kV: 303 to 1500 omega; the damping range of the secondary damping resistor is 30-60 omega;

(3) the damping range of the high damping resistor at 27.5kV is 788-3900 omega, and the damping range of the secondary damping resistor is as follows: 78-156 Ω;

(4) when 35kV, the damping range of the high damping resistor is 1000-4950 omega, and the damping range of the secondary damping resistor is as follows: 99-198 omega;

(5) at 66kV, the damping range of the high damping resistor is 1909-9450 omega, and the damping range of the secondary damping resistor is as follows: 189 omega-378 omega.

Furthermore, the self inductance value of the high-damping resistor is zero, and the resistor is in a shape of a linear sheet, so that the influence of winding and wave-shaped inductive components on lightning current release is prevented; the resistance value does not deviate from the effective damping interval after suddenly reducing under the high temperature state, and the resistance value change interval is as follows: not more than +/-2%; high damping resistor instantaneously discharges maximum lightning current: is more than 350kA/3.5ms.

Further, the shape of the sub-damping resistor is a straight-line sheet, and the self-inductance component is zero.

Further, the grounding transformer is a low-impedance grounding transformer, and the zero-sequence impedance values of the grounding transformers of each voltage class are as follows: 6.3kV Z0 is not more than 2.4 omega, 10.5kV Z0 is not more than 3.75 omega, 27.5kV Z0 is not more than 9.82 omega, 35kV Z0 is not more than 12.5 omega, 66kV Z0 is not more than 26 omega, and the maximum positive error of the zero sequence impedance value is 9.5 percent under the condition of system parameter allowance.

Furthermore, the lightning incident releasing device is installed on a neutral point of a main transformer of a transformer substation or a bus of a distribution station in a protected area, when the neutral point of each system transformer is led out, corresponding devices can be configured to be directly connected according to factors such as different voltage levels, asymmetric capacitance and current of the system and the like, and when the neutral point is not led out, the neutral point is manually manufactured to be connected.

Further, the lightning incident releasing device has the following specific applications:

(1) if the voltage level coil related to the main transformer of the protected transformer substation is a triangular connection, a neutral point can be artificially manufactured and then accessed;

(2) if the relevant voltage level coil of the main transformer of the protected transformer substation is star-connected and the neutral point is led out, the neutral point can be directly accessed;

(3) if the relevant voltage level coil of the main transformer of the protected transformer station is in star connection and the neutral point is led out, if the system possibly has asymmetric capacitance and other factors for a long time, the system is accessed in an equivalent resistance mode.

Further, the circuit breaker is a single-pole vacuum circuit breaker.

The utility model discloses the control method of thunder and lightning incident release device, thunder and lightning incident release device installs on transformer substation main transformer neutral point or the distribution station bus of protected area, and when the electric wire netting takes place single phase ground connection, the digital measurement and control device gathers ground fault current, judges the fault nature through current transformer, if for instantaneous ground connection then automatic filtering, do not trip; if the fault line is permanently grounded, an instruction is sent to drive the breaker to be switched on, the secondary damping resistor is put into use, accurate line selection conditions are provided for a zero sequence protection system of the transformer substation, accurate tripping of the grounded fault line is achieved, and the fault line is isolated from the system. The important degree and the protection action time limit of various lines can be preset and distinguished for zero sequence protection, when a system is grounded in a single phase, if important loads can act on signals or trip within 2 hours of delay, and if secondary loads can act on immediate trip; and if the power grid is grounded in the single phase again, repeating the logic program of the searching judgment and the command action.

Compared with the prior art, the beneficial effects of the utility model are that:

according to the problems of incident impact, superimposed impact evolution, expansion accidents and the like of thunder, a thunder incident releasing device is configured at a neutral point of a transformer substation or a switching station bus or a main transformer in a protected area so as to effectively release a thunder impact wave head, prevent the wave head from being superimposed, prevent the expansion accidents after the evolution, reduce the thunder incident voltage, reduce the high-frequency arc reignition to 0PU, and reduce the fault current in the system from the fault of the high-frequency arc reignition to 0PU

Down to

The shift voltage of the neutral point of the power grid is restrained, the overvoltage amplitude in the power supply system is limited within 1.767PU, the earthing arc is not reignited, the accident is not expanded, and the frequency division resonance, ferromagnetic resonance and disconnection resonance overvoltage in the system can not occur any more. The displacement voltage of the transformer in the system is greatly reduced. Any equipment insulation that exceeds 1.767PU insulation strength is within its scope of protection. The grounding line selection is 100% accurate, instantaneous grounding false tripping is not generated, and the problems of short circuit and electricity interference caused by resonance overvoltage are fundamentally solved;

drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a linear resonant tank.

FIG. 2 is a current-voltage characteristic of a non-linear resonant tank;

FIG. 3 is a non-linear resonant tank circuit with a resistor present;

FIG. 4 is a diagram of primary main wiring after neutral points are artificially created for triangular wiring for the voltage level coils associated with the main transformer of the protected substation;

FIG. 5 is a diagram of a primary main connection of a neutral point, when the voltage level coil associated with the main transformer of the protected substation is star-connected and the neutral point is led out, the neutral point can be directly connected;

fig. 6 is a diagram of a primary main connection line that can be connected by an equivalent resistance method if the system may have asymmetric capacitance and other factors for a long time if the voltage-level coil related to the main transformer of the protected substation is star-connected and the neutral point is led out.

In the figure: 1. a digital measurement and control device; 2. a circuit breaker; 3. a secondary damping resistor; 4. a current transformer; 5. a high damping resistor; 6. and a grounding transformer.

Detailed Description

To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the attached drawings in the embodiments of the present invention are combined below to clearly and completely describe the technical solutions in the embodiments of the present invention, and obviously, the described embodiments are part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. 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.

As shown in fig. 4-6, the lightning incident releasing device is composed of 1 set of high damping resistor 5, 1 set of secondary damping resistor 3, 852 digital measuring and controlling device 1, low impedance grounding transformer 6, current transformer 4, circuit breaker 2, etc., and is installed at the neutral point or bus of the main transformer of the transformer substation in the protected area. The specific configuration is increased and decreased according to factors such as neutral point leading-out conditions of a main transformer of the power distribution network, system operation modes, load properties, zero sequence protection, continuous operation time with grounding and the like.

The high damping resistor:

(1) the zero sequence impedance value of each voltage class grounding transformer matched with the high damping resistor device is as follows: 6.3kV Z0 is less than or equal to 2.4 omega, 10.5kV Z0 is less than or equal to 3.75 omega, 27.5kV Z0 is less than or equal to 9.82 omega, 35kV Z0 is less than or equal to 12.5 omega, 66kV Z0 is less than or equal to 26 omega, and the maximum positive error of the zero sequence impedance value is 9.5 percent under the condition of system parameter allowance;

(2) the self inductance value of the high-damping resistor is zero, and the resistor is in a linear sheet shape, so that the influence of winding and wave-shaped inductive components on lightning current release is prevented;

(3) the damping range of the high damping resistor is 10.5kV as an example: 303-1500 omega, and the damping range of other voltage classes can be converted according to the damping range of a 10.5kV system;

(4) the resistance value does not deviate from the effective damping interval after suddenly reducing under the high temperature state, and the resistance value change interval is as follows: not more than + -2%.

(5) High damping resistor instantaneously discharges maximum lightning current: more than 350kA/3.5ms (reckoning according to the principle of I2t equality)

The secondary damping resistor:

(1) the damping range of the sub-damping resistor is 10.5kV as an example: 30-60 omega.

(2) Self-inductance component of sub-damping resistor and shape of resistor

The shape of the secondary damping resistor is a linear sheet, so that winding and wave shapes are prevented, and the self-inductive component is zero.

(3) Digital measurement and control device: the system consists of a singlechip, a chip, a static relay, a module, software and the like.

(4) And (3) current transformer CT: a conventional configuration.

(5) A circuit breaker: single-pole vacuum circuit breaker.

The function and operation control method of the lightning incident release device comprises the following steps:

(1) Effectively release induced lightning current surge head to reduce lightning incident voltage

After the lightning incident releasing device is connected to a system, the first wave head on the power supply side is instantly released when lightning induction response occurs, and the first wave head on the load side is released by the lightning arrester and then is instantly released by the incident releasing device when the first wave head on the load side is approximately turned back to the power supply side. So far, the process of impact release of the lightning wave head is finished and no invasion is formed. The lightning incident impact current of ABC three phases can be released within 3.5ms.

(2) Effectively inhibit resonance overvoltage of various forms, and avoid expansion of internal overvoltage caused by lightning breakdown and insulation evolution

When the lightning breaks down single-phase insulation or insulation weak points exist in a system, the discharge process of the lightning is finished, and then the discharge process is converted into internal overvoltage of resonance and arc grounding, due to the whole function of the device, frequency division resonance overvoltage of high-frequency arc reignition does not occur, power-frequency arc reignition does not occur, and the amplitude of the overvoltage is less than or equal to 2.3PU. Various forms of resonance overvoltage which can occur in daily operation are comprehensively inhibited, and the breakdown probability of insulation damage is greatly reduced. Namely, after the lightning incident releasing device is connected into the system, various forms of resonance in the system are comprehensively inhibited;

the neutral point is connected with the lightning incident releasing device and then is shown in figure 1: the total pressure drop of the loop will become Δ U', which can be written as

Namely: i, UL and UC are determined by R, do not tend to infinity, and play the damping role of resistance, so as to destroy the resonance condition and prevent resonance from occurring.

The overvoltage amplitude of the whole system is comprehensively inhibited; the problem of neutral point offset of a 6.3KV system, a 10.5KV system, a 27.5KV system, a 35KV system and a 66KV system is common by inhibiting the offset voltage of the neutral point of a power grid, and besides the neutral point grounding mode factor, three factors such as relative ground asymmetric capacitance, a three-phase lead arrangement mode and the like are added. After the incident releasing device is put into use, the voltage deviation can be greatly reduced.

(3) The power supply continuity of important and secondary loads can be distinguished, instantaneous grounding false tripping is avoided, accidents are not expanded, and grounding line selection is 100% accurate.

(1) After the lightning incident releasing device is connected into a system, the accuracy of permanent grounding line selection is 100%, the secondary load acts on immediate tripping, the important load acts on a signal or acts on long-delay tripping according to user requirements, and the power supply continuity of the important load and the secondary load is treated differently. The method avoids the secondary load equipment failure from influencing the power supply continuity of the important load and avoids the important loss caused by sudden power failure of the important load.

(2) Instantaneous grounding automatic filtering, preventing instantaneous grounding of immediate automatic cleaning from being converted into tripping power-off

After the lightning incident release device is connected into a system, the instantaneous grounding of flashover discharge can be mostly eliminated by self, the probability of continuing electric arcs is greatly reduced, the flashover instantaneous grounding of equipment such as an insulator and the like and the permanent grounding of broken insulation are treated differently, and the problem of instantaneous grounding false tripping is avoided. And the probability of enlarging accidents can be greatly reduced without multi-point faults.

(3) The burning loss of the fault point can be reduced, and the high-frequency current does not enter the fault point.

(4) Can solve the problems of short circuit and interference caused by the damage of resonance overvoltage to insulation

The voltage interference causing the greatest harm to the system is that the bus voltage is instantaneously reduced to be below a limit value when the interphase short circuit is broken down, and the undervoltage tripping of equipment such as a motor and the like with undervoltage protection is stopped due to the instantaneous low voltage of the system caused by the short-circuit fault in terms of the accident phenomenon.

The lightning incident releasing device effectively inhibits resonance overvoltage, does not generate resonance damage insulation problem, greatly reduces the inter-phase insulation breakdown probability, and radically eliminates the electricity interference accident.

(5) The working process of the lightning incident releasing device comprises the following steps:

after the lightning incident releasing device is connected into the system, the first wave head at the power supply side when the lightning induction response occurs

Instantaneous releaseFirst wave head on load side

The residual energy is left after the lightning arrester is released

When the circuit is folded back to the power supply side, the circuit is instantaneously released through the incident releasing device. So far, the process of impact release of the lightning wave head is finished and no invasion is formed. When single-phase grounding occurs to a power grid, the digital measurement and control device collects grounding fault current through the first current transformer, judges fault properties, and automatically filters and does not trip if the current is instantaneous grounding (non-metallic grounding); if the circuit breaker is permanently grounded (metallic grounding), an instruction is sent to drive the circuit breaker to be switched on, a first damping resistor is put into the circuit breaker, the zero sequence protection system of the transformer substation accurately selects a line and realizes accurate tripping of a grounding fault line, the fault line is isolated from the system, if the circuit breaker is important load, the circuit breaker can act on a signal or trip after long delay, and then the digital measurement and control device drives the circuit breaker to delay and open the circuit. And if the power grid is grounded in the single phase again, repeating the searching, judging and operating processes. The high damping resistor satisfies the condition of operating for 2 hours in a high temperature state. The conversion of the resistance value is in the uninterrupted high damping resistor grounding mode, namely, the high damping resistor is always in the running state under any working condition.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (5)

1. A thunder incident releasing device is characterized by comprising a high damping resistor, a secondary damping resistor, a current transformer, a grounding transformer, a digital measurement and control device and a circuit breaker, wherein the high damping resistor and the secondary damping resistor are connected in parallel, and the head end of the secondary damping resistor is provided with an open circuit and is controlled by the digital measurement and control device; the high-damping resistor is connected with a current transformer in series, and the current transformer is electrically controlled and connected with the digital measurement and control device; the damping range of the high damping resistor and the damping range of the secondary damping resistor are as follows:

(1) high damping resistor damping range at 6.3 kV: 182 Ω -900 Ω, sub-damping resistor damping range: 18-36 omega;

(2) damping range of high damping resistor at 10.5 kV: 303 to 1500 omega; the damping range of the secondary damping resistor is 30-60 omega;

(3) the damping range of the high damping resistor at 27.5kV is 788-3900 omega, and the damping range of the secondary damping resistor is as follows: 78-156 omega;

(4) at 35kV, the damping range of the high damping resistor is 1000-4950 omega, and the damping range of the secondary damping resistor is as follows: 99-198 omega;

(5) at 66kV, the damping range of the high damping resistor is 1909-9450 omega, and the damping range of the secondary damping resistor is as follows: 189 omega-378 omega.

2. The lightning incident trip unit according to claim 1, characterised in that the high damping resistor has a self-inductance value of zero, the resistor being shaped as a rectilinear sheet; the resistivity does not deviate from the effective damping interval after suddenly dropping at high temperature, and the resistance value change interval is as follows: not more than +/-2%; high damping resistor instantaneously releases maximum lightning current: is more than 350kA/3.5ms.

3. The lightning incident discharge apparatus according to claim 1, wherein the secondary damping resistor has a shape of a straight sheet with zero self-inductance component.

4. The lightning incident-releasing device according to claim 1, wherein the grounding transformer is a low impedance grounding transformer, and the zero sequence impedance value of each voltage class grounding transformer is: 6.3kV Z0 is less than or equal to 2.4 omega, 10.5kV Z0 is less than or equal to 3.75 omega, 27.5kV Z0 is less than or equal to 9.82 omega, 35kV Z0 is less than or equal to 12.5 omega, 66kV Z0 is less than or equal to 26 omega, and the maximum positive error of the zero sequence impedance value is 9.5 percent under the condition of system parameter permission.

5. The lightning incident discharge apparatus according to claim 1, wherein the circuit breaker is a single-pole vacuum circuit breaker.

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