CN116073345B - Intelligent comprehensive grounding management system - Google Patents

Abstract

The invention discloses an intelligent comprehensive grounding management system which comprises a grounding transformer, a high-voltage current-limiting fuse, a single-phase vacuum contactor, an arc suppression coil, a single-phase high-voltage isolating switch, a voltage transformer, a harmonic eliminator, a main controller, a zero-sequence CT and a management background module. When a single-phase grounding fault occurs in a system with a neutral point which is not directly grounded, the management system has the functions of quick and accurate line selection, effective fault processing, overall process voltage monitoring processing and the like, the wavelet energy spectrum can reflect the energy distribution condition of fault signals under various scales, the wavelet energy spectrum analysis method is adopted to analyze the inversion side fault direct current signals, the wavelet energy spectrum of the signals is obtained, and the fault cause causing commutation failure is determined.

Description

Intelligent comprehensive grounding management system

Technical Field

The invention relates to the field of power grid management, in particular to an intelligent comprehensive grounding management system.

Background

At present, when a single-phase earth fault occurs in a neutral point non-direct power system, the single-phase earth fault is usually expressed as an arc earth, and the earth voltage of a non-fault phase line can rise to 3.5 times of rated phase voltage at the highest. Such overvoltages throughout the system tend to cause flashovers to ground at system insulation weaknesses. Meanwhile, the grounding arc is easy to burn the line insulation at the grounding, particularly the cable line, the grounding arc is easy to burn through the inter-phase insulation of the cable to cause the inter-cable short circuit, the cable blasting is caused, and in addition, in the arc grounding process, the system generates intense electromagnetic oscillation due to the change of electromagnetic parameters of the system. In the vibration process, the charge and discharge current of the system capacitor to the ground can form a loop through the neutral point of the voltage transformer in the system when the arc is extinguished and the fault is eliminated. The current is often far greater than the rated current of the voltage transformer, so that the iron core of the transformer is saturated, the primary side current is increased sharply, the fuse of the voltage transformer is fused, and even the voltage transformer is burned.

It is difficult to determine the branch that has a single-phase earth fault. When a single-phase grounding fault occurs in a system, the single-phase grounding fault line selection device based on the small-current line selection principle in the current market collects the magnitude and the direction of zero-sequence capacitance current flowing through each branch and determines the branch with the single-phase grounding fault through different analysis methods. Because the zero sequence capacitance current signal of the system is small and can be influenced by various factors such as the state position of a fault point, the detection accuracy is not high, and thus the safety of electricity utilization of a user is hidden. When the device is applied to a system with a neutral point grounded through an arc suppression coil, the original line selection device based on the power direction line selection principle cannot be used.

In addition, in the actual management process, the development condition of the medium-voltage power transmission and distribution system is seen that the neutral point is not directly grounded, and corresponding defects are brought to the medium-voltage power transmission and distribution system:

1. the neutral point is not directly grounded and the system is easy to generate high-voltage oscillation, thereby causing various overvoltages;

2. when a single-phase earth fault occurs in a system in which the neutral point is not directly grounded, the single-phase earth fault is usually expressed in the form of arc grounding, and the earth voltage of a non-fault phase line can rise to 3.5 times the rated phase voltage at the highest. Such overvoltages throughout the system tend to cause flashovers to ground at system insulation weaknesses. Meanwhile, the grounding arc is easy to burn the line insulation at the grounding, particularly the cable line, and the grounding arc is easy to burn through the inter-phase insulation of the cable to cause inter-phase short circuit of the cable, so that the cable blasting is triggered. In addition, in the arc grounding process, the system generates intense electromagnetic oscillation caused by the change of electromagnetic parameters of the system. In the vibration process, the charge and discharge current of the system capacitor to the ground can form a loop through the neutral point of the voltage transformer in the system when the arc is extinguished and the fault is eliminated. The direct current is often far greater than the rated current of the voltage transformer, so that the iron core of the transformer is saturated, the primary side current is increased sharply, the fuse of the voltage transformer is blown, and even the voltage transformer is burned.

3. It is difficult to determine the branch that has a single-phase earth fault. When a single-phase grounding fault occurs in a system, the single-phase grounding fault line selection device based on the small-current line selection principle in the current market collects the magnitude and the direction of zero-sequence capacitance current flowing through each branch and determines the branch with the single-phase grounding fault through different analysis methods. Because the zero sequence capacitance current signal of the system is small and can be influenced by various factors such as the state and the position of the fault point, the detection accuracy is not high, and therefore hidden danger is brought to the electricity utilization safety of a user. When the device is applied to a system with a neutral point grounded through an arc suppression coil, the original line selection device based on the power direction line selection principle cannot be used.

4. The existing fault voltage monitoring device can not truly record and analyze transient overvoltage such as arc light, thunder and lightning, operation and the like suffered by the system.

For the problems in the related art, no effective solution has been proposed at present.

Disclosure of Invention

Aiming at the problems in the related art, the invention provides an intelligent comprehensive grounding management system for overcoming the technical problems existing in the prior related art.

For this purpose, the invention adopts the following specific technical scheme:

an intelligent comprehensive grounding management system manages the system and comprises a grounding transformer, a high-voltage current-limiting fuse, a single-phase vacuum contactor, an arc suppression coil, a single-phase high-voltage isolating switch, a voltage transformer, a harmonic eliminator, a main controller, a zero sequence CT and a management background module;

the grounding transformer is used for providing a neutral point for the power system;

the high-voltage current-limiting fuse is used for protecting overload or short circuit of power equipment;

the single-phase vacuum contactor is used for transferring high-frequency grounding capacitance current flowing through a fault point and eliminating arc grounding overvoltage of the power system;

the arc suppression coil is used for providing safety protection for power supply of the power system;

the single-phase high-voltage isolating switch is used for connecting the neutral point of the grounding transformer with the ground;

the voltage transformer is used for changing the voltage on the line change;

the harmonic eliminator is used for eliminating resonance of a voltage transformer of the power system;

the main controller is used for comparing the current waveforms of the zero sequence CT of all the outgoing lines and judging fault branches, fault types and fault time;

the zero sequence CT is used for outputting zero sequence current by the secondary side of the transformer when an electric shock or electric leakage fault occurs in the power system, so that equipment on the connected secondary line can perform protection action;

the management background module is used for monitoring and managing the data information of the main controller in real time.

Further, the step of providing the neutral point for the power system includes the steps of:

matching a grounding transformer with a main bus in a power system, and installing a controllable grounding resistor at a neutral point of the grounding transformer;

when the power system is grounded, the voltage at the two ends is in zero crossing vicinity to enable the neutral point to be instantaneously conducted with the ground, and a path of short-circuit current is generated;

the short circuit current is grounded through the grounded fault point, and the increased short circuit current of each feeder line is detected by the microcomputer controller and the line with increased current is marked as a grounded line.

Further, the transferring the high-frequency grounding capacitor current flowing through the fault point, and eliminating the arc grounding overvoltage of the power system comprises the following steps:

when a single-phase grounding fault occurs in the power system, the main controller completes control after line selection and starts a fault phase vacuum contactor;

the vacuum contactor transfers high-frequency grounding capacitance current flowing through the fault point and eliminates arc grounding overvoltage;

tuning the arc suppression coil and opening the vacuum contactor for the fault phase.

Further, the step of providing safety protection for the power supply of the power system comprises the following steps:

in the opening process of the vacuum contactor, the arc suppression coil is grounded to the capacitance current, and the grounded capacitance current is prevented from flowing through a fault point;

the cable branch in the fault branch is prevented from being upgraded from single-phase earth fault to interphase short-circuit accident, and the operation overvoltage generated when the vacuum contactor is opened is avoided.

Further, the comparing the current waveforms of the zero sequence CTs of all the outgoing lines and judging the fault branch, the fault type and the fault time includes the following steps:

collecting voltage waveforms and current waveforms generated by the power system in a fault state;

preprocessing a voltage waveform and a current waveform by adopting a wavelet energy spectrum analysis method to obtain a distribution diagram of a wavelet energy spectrum;

determining wavelet energy spectrum values of a voltage waveform and a current waveform according to a distribution diagram of a wavelet energy spectrum analysis method, and extracting data information of fault characteristics;

and uploading the data information of the fault characteristics to a management background module in real time.

Further, the construction of the wavelet energy spectrum analysis method comprises the following steps:

determining the window area of wavelet analysis, wherein the areas of a time window and a frequency window are fixed, but the shapes of the time window and the frequency window are variable;

transforming the base wavelet in the window area into a mother wavelet function through Fourier transformation to obtain a wavelet sequence;

and calculating the discrete value of the function in the wavelet sequence according to the information of each scale and position in the wavelet sequence.

Further, the calculation formula of the wavelet sequence is as follows:

；

in the method, in the process of the invention,

is a scale parameter->

For translation parameters->

Is a basis wavelet function, +.>

As a function.

Further, the preprocessing of the voltage waveform and the current waveform by using a wavelet energy spectrum analysis method to obtain a distribution diagram of the wavelet energy spectrum comprises the following steps of;

calculating energy levels of each scale of the voltage waveform and the current waveform through wavelet energy spectrum analysis, and extracting characteristics of fault signals on each frequency band;

and processing the characteristics on each frequency band, and extracting a distribution diagram of wavelet energy spectrums of voltage and current when the fault signal fails to commutate.

Further, the calculating the discrete value of the function in the wavelet sequence according to the information of each scale and position in the wavelet sequence comprises the following steps:

calculating the energy of fault direct current information according to the equality of the wavelet energy in the time domain and the wavelet domain during wavelet transformation;

defining a wavelet energy spectrum of fault current information according to the distribution of the wavelet energy spectrum along a scale axis;

defining a wavelet energy spectrum sequence under discrete wavelet transformation, and calculating current wavelet energy;

and comparing the wavelet energy with a normal energy value to obtain a deviation value and fault information.

Further, the method comprises the steps of, the real-time monitoring and managing of the data information of the main controller comprises the following steps:

when a fault occurs, alarm information is sent to a background and a mobile terminal APP;

judging the current fault state according to the fed-back fault information, and processing the fault state to recover the power supply of the power system;

and further analyzing the working state of the power supply system after the fault occurs, so as to avoid the fault from happening again.

The beneficial effects of the invention are as follows:

1. when a single-phase grounding fault occurs in a system with a neutral point which is not directly grounded, the management system has multiple functions of quick and accurate line selection, effective fault processing, overall process voltage monitoring processing and the like.

2. The management system has strong universality and flexibility, is suitable for a system in which the neutral point of 3-35 KV medium voltage transmission and distribution is not directly grounded, and can be flexibly assembled and configured according to different systems of users to meet the field requirements.

3. The management system of the invention has the advantages that the real-time synchronous high-speed acquisition system samples data, the sampling rate of zero sequence current and voltage of all loops reaches more than 12.8K, the synchronous precision is within 10us, various conditions of the system are rapidly and accurately judged, the main control unit adopts a 32-bit high-performance DSP, the whole Chinese interface passes the IV-level electromagnetic anti-interference type test; the high-precision hardware clock chip is adopted, and the controller can still normally time after power failure; the controller has 100 event sequence records and has a self-checking function, can detect, analyze, record and store main parts of the controller, is convenient to maintain, is of a split board plug-in unit and board type structure, is closed and resists strong vibration; the controller has a wireless communication function, the data is uploaded to the cloud, and the PC and the mobile phone APP are synchronously monitored and managed in real time.

4. The grounding variable center point is connected with the adjustable-gear arc suppression coil, so that the ground capacitance current is compensated for full amount, and the problem of arc grounding point overcurrent is perfectly solved; the three-phase high-voltage electric system is connected with the quick contactor, and the arc grounding device is changed into metal grounding at the first time, so that the problem of cable breakdown blasting caused by arc grounding overvoltage is perfectly solved; when the electric power system is not grounded but has thunder or overvoltage operation, an overvoltage protector is adopted to protect the high-voltage system in time; when necessary, a high-voltage resistor is additionally arranged between the grounding variable center point and the ground wire to limit the current of the grounding variable center point, so that the grounding variable is protected from being damaged; and a rapid and accurate heavy current line selection module IIR and an FIR algorithm are adopted to perfectly extract the correct signals.

5. The wavelet energy spectrum has unique advantages in the aspect of extracting fault characteristics, can reflect the energy distribution condition of fault signals under each scale, analyzes the inversion side fault direct current signals by adopting a wavelet energy spectrum analysis method to obtain the wavelet energy spectrum of the signals, and determines the fault cause causing commutation failure.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic block diagram of an intelligent integrated ground management system according to an embodiment of the present invention.

In the figure:

1. a grounding transformer; 2. a high voltage current limiting fuse; 3. a single phase vacuum contactor; 4. arc suppression coil; 5. a single-phase high-voltage isolating switch; 6. a voltage transformer; 7. a resonance eliminator; 8. a main controller; 9. zero sequence CT; 10. and managing a background module.

Detailed Description

For the purpose of further illustrating the various embodiments, the present invention provides the accompanying drawings, which are a part of the disclosure of the present invention, and which are mainly used to illustrate the embodiments and, together with the description, serve to explain the principles of the embodiments, and with reference to these descriptions, one skilled in the art will recognize other possible implementations and advantages of the present invention, wherein elements are not drawn to scale, and like reference numerals are generally used to designate like elements.

According to an embodiment of the invention, an intelligent integrated ground management system is provided.

The invention will be further described with reference to the accompanying drawings and the specific embodiments, as shown in fig. 1, an intelligent comprehensive grounding management system according to an embodiment of the invention, wherein the management system comprises a grounding transformer 1, a high-voltage current limiting fuse 2, a single-phase vacuum contactor 3, an arc suppression coil 4, a single-phase high-voltage isolating switch 5, a voltage transformer 6, a harmonic eliminator 7, a main controller 8, a zero sequence CT9 and a management background module 10;

the grounding transformer 1 is used for providing a neutral point for a power system;

in one embodiment, the providing a neutral point for the power system comprises the steps of:

matching a grounding transformer with a main bus in a power system, and installing a controllable grounding resistor at a neutral point of the grounding transformer;

when the power system is grounded, the voltage at the two ends is in zero crossing vicinity to enable the neutral point to be instantaneously conducted with the ground, and a path of short-circuit current is generated;

the short circuit current is grounded through the grounded fault point, and the increased short circuit current of each feeder line is detected by the microcomputer controller and the line with increased current is marked as a grounded line.

Specifically, the grounding transformer 1:10KV product model: DKSC-180/10Zn connection method, 35KV product model: DKSC-315/35Zn connection provides a neutral point for a system with neutral points not directly grounded, and provides a zero sequence current channel when single-phase grounding occurs.

The high-voltage current-limiting fuse 2 is used for protecting overload or short circuit of power equipment;

specifically, the high-voltage current-limiting fuse 2 is of a 10KV product model: XRNT-12, rated voltage: 12KV rated current: 31.5A;35KV product model: XRNT-40.5 rated voltage: 40.5KV rated current: 16A.

The single-phase vacuum contactor 3 is used for transferring high-frequency grounding capacitance current flowing through a fault point and eliminating arc grounding overvoltage of the power system;

in one embodiment, the transferring the high frequency ground capacitor current flowing through the fault point, eliminating the arc ground overvoltage of the power system comprises the steps of:

when a single-phase grounding fault occurs in the power system, the main controller completes control after line selection and starts a fault phase vacuum contactor;

the vacuum contactor transfers high-frequency grounding capacitance current flowing through the fault point and eliminates arc grounding overvoltage;

tuning the arc suppression coil and opening the vacuum contactor for the fault phase.

Specifically, the single-phase vacuum contactor 3 is of the type of 10 KV: JCZT-12/630;35KV product model; JCZT3-40.5/630.

The arc suppression coil 4 is used for providing safety protection for power supply of the power system;

in one embodiment, the providing safety protection for the power system supply includes the steps of:

in the opening process of the vacuum contactor, the arc suppression coil is grounded to the capacitance current, and the grounded capacitance current is prevented from flowing through a fault point;

the cable branch in the fault branch is prevented from being upgraded from single-phase earth fault to interphase short-circuit accident, and the operation overvoltage generated when the vacuum contactor is opened is avoided.

Specifically, the arc suppression coil 4 is of a 10KV product model: XDC-50/10 maximum compensation inductor current 50A;35KV product model: XDC-35/30 maximum offset inductor current 30A.

The single-phase high-voltage isolating switch 5 is used for connecting the neutral point of the grounding transformer with the ground;

specifically, the single-phase high-voltage isolating switch 5 is of the type of 10 KV: GN19-12C/630;35KV product model: GN27-40.5/630A.

The voltage transformer 6 is used for changing the voltage on the line change;

specifically, the model of the voltage transformer 6: LXK-120; transformation ratio: 200/1; protection level: 10P10.

The resonance eliminator 7 is used for eliminating resonance of a voltage transformer of the power system;

the main controller 8 is used for comparing the current waveforms of the zero sequence CTs of all outgoing lines and judging fault branches, fault types and fault time;

in one embodiment, the comparing the current waveforms of the zero sequence CTs of all outgoing lines and judging the fault branch, the fault type and the fault time includes the following steps:

collecting voltage waveforms and current waveforms generated by the power system in a fault state;

preprocessing a voltage waveform and a current waveform by adopting a wavelet energy spectrum analysis method to obtain a distribution diagram of a wavelet energy spectrum;

determining wavelet energy spectrum values of a voltage waveform and a current waveform according to a distribution diagram of a wavelet energy spectrum analysis method, and extracting data information of fault characteristics;

and uploading the data information of the fault characteristics to a management background module in real time.

In one embodiment, the construction of the wavelet energy spectrum analysis method comprises the steps of:

determining the window area of wavelet analysis, wherein the areas of a time window and a frequency window are fixed, but the shapes of the time window and the frequency window are variable;

transforming the base wavelet in the window area into a mother wavelet function through Fourier transformation to obtain a wavelet sequence;

and calculating the discrete value of the function in the wavelet sequence according to the information of each scale and position in the wavelet sequence.

In one embodiment, the wavelet sequence is calculated by the formula:

；

in the method, in the process of the invention,

is a scale parameter->

For translation parameters->

Is a basis wavelet function, +.>

As a function.

In one embodiment, the preprocessing of the voltage waveform and the current waveform by using the wavelet energy spectrum analysis method to obtain a distribution map of the wavelet energy spectrum comprises the following steps;

calculating energy levels of each scale of the voltage waveform and the current waveform through wavelet energy spectrum analysis, and extracting characteristics of fault signals on each frequency band;

and processing the characteristics on each frequency band, and extracting a distribution diagram of wavelet energy spectrums of voltage and current when the fault signal fails to commutate.

Specifically, the wavelet analysis is a time-frequency localization analysis method with a fixed window area, but a changeable shape and changeable time window and frequency window; wavelet analysis has a higher frequency resolution and a lower time resolution in the low frequency portion and conversely a higher time resolution and a lower frequency resolution in the high frequency portion.

In one embodiment, the calculating the discrete value of the function in the wavelet sequence according to the information of each scale and position in the wavelet sequence comprises the following steps:

calculating the energy of fault direct current information according to the equality of the wavelet energy in the time domain and the wavelet domain during wavelet transformation;

defining a wavelet energy spectrum of fault current information according to the distribution of the wavelet energy spectrum along a scale axis;

defining a wavelet energy spectrum sequence under discrete wavelet transformation, and calculating current wavelet energy;

and comparing the wavelet energy with a normal energy value to obtain a deviation value and fault information.

In one embodiment, the formula for calculating the energy of the fault information is:

；

in the method, in the process of the invention,

for the current fault information ++>

For wavelet transform coefficients of the signal, +.>

Is a scale parameter->

Is a translation parameter.

In one embodiment, the wavelet energy spectrum is defined by the formula:

；

in the method, in the process of the invention,

representation->

Wavelet energy at scale, +.>

Is->

Wavelet transform coefficient under scale, +.>

For the length of the wavelet transform coefficients, +.>

Is a coefficient.

In one embodiment, the sequence of wavelet energy spectra is:

；

in the method, in the process of the invention,

is->

Wavelet energy at scale.

In particular, the wavelet transform has equidistant characteristics, i.e. the wavelet transform of the signal is energy conserving, the energy being equal in the time domain and the wavelet domain; and calculating the energy level of the fault information in each scale through wavelet energy spectrum analysis, extracting the characteristics of the fault signal on each frequency band, and distinguishing different fault information.

The zero sequence CT9 is used for outputting zero sequence current by the secondary side of the transformer when an electric shock or electric leakage fault occurs in the power system, so that equipment on the connected secondary line can perform protection action;

the management background module 10 is configured to monitor and manage data information of the main controller in real time.

In one embodiment, the real-time monitoring and managing of the data information of the main controller includes the steps of:

when a fault occurs, alarm information is sent to a background and a mobile terminal APP;

judging the current fault state according to the fed-back fault information, and processing the fault state to recover the power supply of the power system;

and further analyzing the working state of the power supply system after the fault occurs, so as to avoid the fault from happening again.

Example 1

Through the accident that the stator coil of the No. 1 generator burns out, which occurs in 11 months 26 of Jiangsu Su paper industry, inc., we find that from the accident occurrence time (11 months 26 days 20 points 39 minutes) to the disconnection of No. 1 generator 23 points 33 minutes, the disconnection of No. 3 generator 0 points 14 minutes, the whole power grid system ground disappears, and the neutral point overvoltage protector of the No. 3 generator breaks down and explodes and has arc discharge phenomenon during the fault investigation. During which the system is always in a single-phase earth fault state and the fault time exceeds the safe operating protocol by 2 hours. The main reason for burning out the stator coils of the generator is also that the overvoltage and the overcurrent are caused when the system generates single-phase grounding and short-circuit faults, and in order to avoid the occurrence of the accidents, a reasonable optimization of the whole transformer station system is very necessary.

The accurate line selection method for the integrated KM-JC-X grounding fault treatment system additionally arranged in the electric power system is that a line selection auxiliary current increment device is connected with the ground on a neutral point of the power supply system, corresponding action control is matched, signal acquisition and measurement are carried out, a special program is used for analysis and judgment, and the like, so that hundred percent accuracy of arc grounding and metal grounding of the system can be solved, fault signals are timely sent to a background monitoring platform through communication, and operators on duty can timely treat faults.

In summary, by means of the technical scheme, when a single-phase grounding fault occurs in the neutral point non-direct grounding system, the management system has multiple functions of quick and accurate line selection, effective fault processing, overall process voltage monitoring processing and the like, has strong universality and flexibility, is suitable for the 3-35 KV medium-voltage power transmission and distribution neutral point non-direct grounding system, can be flexibly assembled and configured according to different systems of users, and meets field requirements; the management system of the invention has the advantages that the real-time synchronous high-speed acquisition system samples data, the sampling rate of zero sequence current and voltage of all loops reaches more than 12.8K, the synchronous precision is within 10us, various conditions of the system are rapidly and accurately judged, the main control unit adopts a 32-bit high-performance DSP, the whole Chinese interface passes the IV-level electromagnetic anti-interference type test; the high-precision hardware clock chip is adopted, and the controller can still normally time after power failure; the controller has 100 event sequence records and has a self-checking function, can detect, analyze, record and store main parts of the controller, is convenient to maintain, is of a split board plug-in unit and board type structure, is closed and resists strong vibration; the controller has a wireless communication function, the data is uploaded to the cloud end, and the PC and the mobile phone APP are synchronously monitored and managed in real time; the grounding variable center point is connected with the adjustable-gear arc suppression coil, so that the ground capacitance current is compensated for full amount, and the problem of arc grounding point overcurrent is perfectly solved; the three-phase high-voltage electric system is connected with the quick contactor, and the arc grounding device is changed into metal grounding at the first time, so that the problem of cable breakdown blasting caused by arc grounding overvoltage is perfectly solved; when the electric power system is not grounded but has thunder or overvoltage operation, an overvoltage protector is adopted to protect the high-voltage system in time; when necessary, a high-voltage resistor is additionally arranged between the grounding variable center point and the ground wire to limit the current of the grounding variable center point, so that the grounding variable is protected from being damaged; adopting a rapid and accurate heavy current line selection module IIR and an FIR algorithm to perfectly extract a correct signal; the wavelet energy spectrum has unique advantages in the aspect of extracting fault characteristics, can reflect the energy distribution condition of fault signals under each scale, analyzes the inversion side fault direct current signals by adopting a wavelet energy spectrum analysis method to obtain the wavelet energy spectrum of the signals, and determines the fault cause causing commutation failure.

The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Claims (6)

1. The intelligent comprehensive grounding management system is characterized by comprising a grounding transformer, a high-voltage current-limiting fuse, a single-phase vacuum contactor, an arc suppression coil, a single-phase high-voltage isolating switch, a voltage transformer, a harmonic eliminator, a main controller, a zero sequence CT and a management background module;

the grounding transformer is used for providing a neutral point for the power system;

the high-voltage current-limiting fuse is used for protecting overload or short circuit of power equipment;

the single-phase vacuum contactor is used for transferring high-frequency grounding capacitance current flowing through a fault point and eliminating arc grounding overvoltage of the power system;

the arc suppression coil is used for providing safety protection for power supply of the power system;

the single-phase high-voltage isolating switch is used for connecting the neutral point of the grounding transformer with the ground;

the voltage transformer is used for changing the voltage on the line change;

the harmonic eliminator is used for eliminating resonance of a voltage transformer of the power system;

the main controller is used for comparing the current waveforms of the zero sequence CT of all the outgoing lines and judging fault branches, fault types and fault time; collecting voltage waveforms and current waveforms generated by the power system in a fault state;

preprocessing a voltage waveform and a current waveform by adopting a wavelet energy spectrum analysis method to obtain a distribution diagram of a wavelet energy spectrum;

determining wavelet energy spectrum values of a voltage waveform and a current waveform according to a distribution diagram of a wavelet energy spectrum analysis method, and extracting data information of fault characteristics;

uploading the data information of the fault characteristics to a management background module in real time;

determining the window area of wavelet analysis, wherein the areas of a time window and a frequency window are fixed, but the shapes of the time window and the frequency window are variable;

transforming the base wavelet in the window area into a mother wavelet function through Fourier transformation to obtain a wavelet sequence;

calculating the discrete value of the function in the wavelet sequence according to the information of each scale and position in the wavelet sequence;

the zero sequence CT is used for outputting zero sequence current by the secondary side of the transformer when an electric shock or electric leakage fault occurs in the power system, so that equipment on the connected secondary line can perform protection action;

the management background module is used for monitoring and managing the data information of the main controller in real time;

the calculating of the discrete value of the function in the wavelet sequence according to the information of each scale and position in the wavelet sequence comprises the following steps:

calculating the energy of fault direct current information according to the equality of the wavelet energy in the time domain and the wavelet domain during wavelet transformation;

defining a wavelet energy spectrum of fault current information according to the distribution of the wavelet energy spectrum along a scale axis;

defining a wavelet energy spectrum sequence under discrete wavelet transformation, and calculating current wavelet energy;

comparing the wavelet energy with a normal energy value to obtain a deviation value and fault information;

the real-time monitoring and managing of the data information of the main controller comprises the following steps:

when a fault occurs, alarm information is sent to a background and a mobile terminal APP;

judging the current fault state according to the fed-back fault information, and processing the fault state to recover the power supply of the power system;

and further analyzing the working state of the power supply system after the fault occurs, so as to avoid the fault from happening again.

2. An intelligent integrated ground management system as set forth in claim 1, wherein said providing a neutral point for the power system comprises the steps of:

matching a grounding transformer with a main bus in a power system, and installing a controllable grounding resistor at a neutral point of the grounding transformer;

when the power system is grounded, the voltage at the two ends is in zero crossing vicinity to enable the neutral point to be instantaneously conducted with the ground, and a path of short-circuit current is generated;

the short circuit current is grounded through the grounded fault point, and the increased short circuit current of each feeder line is detected by the microcomputer controller and the line with increased current is marked as a grounded line.

3. The intelligent integrated ground management system of claim 1, wherein said diverting high frequency ground capacitor current through the fault point to eliminate arc ground overvoltage in the power system comprises the steps of:

when a single-phase grounding fault occurs in the power system, the main controller completes control after line selection and starts a fault phase vacuum contactor;

the vacuum contactor transfers high-frequency grounding capacitance current flowing through the fault point and eliminates arc grounding overvoltage;

tuning the arc suppression coil and opening the vacuum contactor for the fault phase.

4. An intelligent integrated ground management system as set forth in claim 1, wherein said providing safety protection for power systems comprises the steps of:

in the opening process of the vacuum contactor, the arc suppression coil is grounded to the capacitance current, and the grounded capacitance current is prevented from flowing through a fault point;

the cable branch in the fault branch is prevented from being upgraded from single-phase earth fault to interphase short-circuit accident, and the operation overvoltage generated when the vacuum contactor is opened is avoided.

5. The intelligent integrated ground management system of claim 1, wherein the wavelet sequence has a calculation formula:

；

in the method, in the process of the invention,

is a scale parameter->

For translation parameters->

Is a basis wavelet function, +.>

As a function.

6. The intelligent integrated grounding management system of claim 1, wherein the preprocessing of the voltage waveform and the current waveform by using a wavelet energy spectrum analysis method to obtain a distribution map of the wavelet energy spectrum comprises the following steps of;

calculating energy levels of each scale of the voltage waveform and the current waveform through wavelet energy spectrum analysis, and extracting characteristics of fault signals on each frequency band;

and processing the characteristics on each frequency band, and extracting a distribution diagram of wavelet energy spectrums of voltage and current when the fault signal fails to commutate.

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