CN113608031A - Method and device for monitoring impulse impedance of transformer substation lightning arrester - Google Patents
Method and device for monitoring impulse impedance of transformer substation lightning arrester Download PDFInfo
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Abstract
The invention discloses a method and a device for monitoring impulse impedance of a transformer substation lightning arrester. The method comprises the following steps: acquiring an electric field value of a high-altitude cloud layer; judging whether lightning is generated around the lightning arrester or not according to the high-altitude cloud layer electric field value; if the lightning is generated, acquiring a current signal flowing through the lightning arrester and voltage signals at two ends of the lightning arrester, and calculating an impulse impedance value according to the current signal and the voltage signals; if no lightning is generated, calculating the potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, the source current value and the pre-stored lightning current, and calculating the impulse impedance value based on the potential difference between every two points on the lightning arrester; lightning current is a current signal measured when lightning actually occurs. The invention realizes the real-time monitoring of the impulse impedance of the lightning arrester.
Description
Technical Field
The invention relates to the field of lightning arrester monitoring, in particular to a method and a device for monitoring impulse impedance of a transformer substation lightning arrester.
Background
The transformer substation is the junction of an electric power system, large-area power failure is caused once equipment damage accidents caused by lightning strike occur, the internal insulation of high-voltage electrical equipment such as a transformer and the like mostly has no self-recovery performance, the equipment is difficult to repair after being damaged by the lightning strike, long-time power failure is caused, equipment damage and direct power supply loss are caused, and national economy and people life are seriously influenced. Therefore, the measurement of the impulse impedance of the arrester is an indispensable link in the construction of the transformer substation, and the measurement and analysis of the impulse impedance of the arrester equipment of the transformer substation can ensure that the protection of the transformer substation is more reliable. Generally, the surge impedance is the ground impedance presented by the ground body under a lightning current surge.
The impulse impedance of the arrester in the lightning protection device of the power station is an important parameter for designing the transformer substation and ensuring the normal operation of the transformer substation, and the impulse impedance is very necessary to be accurately measured and mainly embodied in the following points: 1. and measuring the real grounding impedance of the grounding device, checking whether the grounding resistance of the new grounding network meets the design requirement, and checking whether the grounding resistance of the old grounding network changes. 2. And checking the calculated value to check the correctness of the calculation method and provide a basis for the popularization and application of a new calculation method or software. 3. The rise in ground potential and the change in potential over the entire period due to the power system ground fault current are determined. 4. The suitability of the lightning protection grounding device is determined. 5. And acquiring design data necessary for transformer substation lightning protection, equipment lightning protection and related personal safety.
With the development of power systems, the scale of power grids is continuously enlarged, various microcomputer monitoring devices are also commonly used, people are not satisfied with the capability of accurately measuring the impulse impedance, and the real-time monitoring of the impulse impedance of grounding equipment becomes the current requirement of people. However, at present, the surge impedance can only be measured under a power frequency condition or when lightning comes, and the surge impedance of the lightning arrester cannot be monitored in real time, so that the safety detection of a transformer substation is not enough, and the reliability of the protection of the transformer substation still needs to be improved.
Disclosure of Invention
Based on this, the embodiment of the invention provides a method and a device for monitoring impulse impedance of a transformer substation lightning arrester, which can monitor not only temporary impulse impedance of lightning current but also impulse impedance of the lightning arrester when no lightning is generated, thereby realizing real-time monitoring of the impulse impedance of the lightning arrester and improving the reliability of transformer substation protection.
In order to achieve the purpose, the invention provides the following scheme:
a surge impedance monitoring method for a transformer substation lightning arrester comprises the following steps:
acquiring an electric field value of a high-altitude cloud layer;
judging whether lightning is generated around the lightning arrester or not according to the high-altitude cloud layer electric field value to obtain a first judgment result;
if the first judgment result is yes, acquiring a current signal flowing through the lightning arrester and voltage signals at two ends of the lightning arrester, and calculating an impulse impedance value according to the current signal and the voltage signals;
if the first judgment result is negative, calculating the potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, the source current value and the pre-stored lightning current to obtain a first potential difference, and calculating the impulse impedance value based on the first potential difference; the lightning current is a current signal measured when lightning actually occurs.
Optionally, the method for monitoring impulse impedance of a transformer substation lightning arrester further includes:
and comparing the impact resistance value with a set safety value, and sending an alarm signal when the impact resistance value exceeds the set safety value.
Optionally, the calculating a potential difference between each two points on the arrester according to the radius of the arrester, the source current value, and the pre-stored lightning current to obtain a first potential difference, and calculating the impulse impedance value based on the first potential difference specifically includes:
and calculating the potential difference between every two points on the lightning arrester by adopting a time domain finite difference method according to the radius of the lightning arrester, the source current value and the pre-stored lightning current to obtain a first potential difference, and calculating the impulse impedance value based on the first potential difference.
Optionally, the calculating, by using a time-domain finite difference method, a potential difference between each two points on the arrester from the radius of the arrester, the source current value, and the pre-stored lightning current to obtain a first potential difference, and calculating the impulse impedance value based on the first potential difference specifically includes:
calculating the attenuation coefficient of the current flowing between every two points on the lightning arrester according to the radius of the lightning arrester and the source current value;
calculating the potential difference between every two points on the lightning arrester according to the attenuation coefficient to obtain a plurality of first potential differences;
calculating the potential difference of the lightning arrester according to all the first potential differences to obtain a second potential difference;
judging whether the second potential difference is smaller than a set potential value or not to obtain a second judgment result;
if the second judgment result is yes, calculating an impact resistance value according to the first potential difference;
and if the second judgment result is negative, replacing the source current value with a pre-stored lightning current to update the attenuation coefficient until the second potential difference is smaller than the set potential value, and calculating the impulse impedance value corresponding to the first potential difference when the second potential difference is smaller than the set potential value.
Optionally, calculating an impulse impedance value from the current signal and the voltage signal specifically includes:
and carrying out convolution transformation processing on the current signal and the voltage signal to obtain an impulse impedance value.
Optionally, the determining, by the high cloud layer electric field value, whether lightning is to be generated around the lightning arrester specifically includes:
if the electric field value of the high-altitude cloud layer is larger than the set electric field value, determining that lightning is generated around the lightning arrester;
and if the electric field value of the high-altitude cloud layer is not greater than the set electric field value, determining that no lightning is generated around the lightning arrester.
The invention also provides a device for monitoring the impulse impedance of the transformer substation lightning arrester, which comprises:
the system comprises an atmospheric electric field measuring module, a main control computer and an impact impedance measuring device;
the main control computer is positioned in the control room; the impulse impedance measuring device is connected with the lightning arrester; the main control computer is respectively connected with the atmospheric electric field measuring module and the impact impedance measuring device;
the atmospheric electric field measurement module is used for: measuring the electric field value of the high-altitude cloud layer;
the main control computer is used for:
judging whether lightning is generated around the lightning arrester according to the high-altitude cloud layer electric field value, if so, sending a lightning coming permission signal to the impulse impedance measuring device, and if not, sending a blocking signal to the impulse impedance measuring device;
the surge impedance measuring device is used for:
after receiving the lightning coming permission signal, detecting a current signal flowing through the lightning arrester and voltage signals at two ends of the lightning arrester, and sending the current signal and the voltage signals to the main control computer;
converting the locking signal into a real-time monitoring allowing signal after receiving the locking signal, and sending the real-time monitoring allowing signal to the main control computer;
the master control computer is further configured to:
calculating a surge impedance value from the current signal and the voltage signal when lightning is to be generated around the lightning arrester;
when no lightning is generated around the lightning arrester, calculating potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, a source current value and pre-stored lightning current to obtain first potential difference, and calculating the impulse impedance value based on the first potential difference; the lightning current is a current signal measured when lightning actually occurs.
Optionally, the surge impedance monitoring device of the lightning arrester of the transformer substation further includes: indicator lights and alarm devices; the indicator light and the alarm equipment are positioned in the control room and are connected with the main control computer;
the indicator light and alarm device is used for:
and when the impact resistance value exceeds a set safety value, sending out an alarm signal.
Optionally, the surge impedance monitoring device of the lightning arrester of the transformer substation further includes: an oscilloscope; the oscilloscope is positioned in the control room and is connected with the main control computer;
the oscilloscope is used for:
storing the current signal and the voltage signal.
Optionally, a finite difference time domain simulation program and a convolution transformation processing program are built in the main control computer.
Compared with the prior art, the invention has the beneficial effects that:
the embodiment of the invention provides a method and a device for monitoring impulse impedance of a transformer substation lightning arrester, wherein the method comprises the steps of firstly judging whether lightning around the lightning arrester is to be generated or not according to a high-altitude cloud-layer electric field value; if the lightning is generated, acquiring a current signal flowing through the lightning arrester and voltage signals at two ends of the lightning arrester, and calculating an impulse impedance value according to the current signal and the voltage signals; if no lightning is generated, calculating the potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, the source current value and the pre-stored lightning current, and calculating the impulse impedance value based on the potential difference between every two points on the lightning arrester. The lightning arrester surge impedance monitoring system can monitor the surge impedance of the lightning arrester when no lightning is generated, realizes real-time monitoring of the surge impedance of the lightning arrester, and improves the reliability of transformer substation protection.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used 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 it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
Fig. 1 is a flowchart of a method for monitoring surge impedance of a transformer substation arrester according to an embodiment of the present invention;
fig. 2 is a schematic diagram of calculating an impulse impedance value by using a time domain finite difference method according to an embodiment of the present invention;
fig. 3 is a block diagram of a surge impedance monitoring device for a transformer substation lightning arrester according to an embodiment of the present invention;
fig. 4 is a more specific structural schematic diagram of a surge impedance monitoring device for a transformer substation lightning arrester according to an embodiment of the present invention;
fig. 5 is a schematic circuit diagram of an impulse impedance measuring apparatus according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a flowchart of a method for monitoring surge impedance of a transformer substation lightning arrester according to an embodiment of the present invention. Referring to fig. 1, the method for monitoring impulse impedance of a transformer substation lightning arrester of the present embodiment includes:
step 101: and acquiring the electric field value of the high-altitude cloud layer.
Step 102: and judging whether lightning is generated around the lightning arrester or not according to the high-altitude cloud layer electric field value to obtain a first judgment result. The method specifically comprises the following steps:
if the electric field value of the high-altitude cloud layer is larger than the set electric field value, determining that lightning is generated around the lightning arrester; and if the electric field value of the high-altitude cloud layer is not greater than the set electric field value, determining that no lightning is generated around the lightning arrester.
Step 103: and if the first judgment result is yes, acquiring a current signal flowing through the lightning arrester and voltage signals at two ends of the lightning arrester, and calculating an impulse impedance value according to the current signal and the voltage signals.
Wherein, calculating an impulse impedance value from the current signal and the voltage signal specifically comprises: and carrying out convolution transformation processing on the current signal and the voltage signal to obtain an impulse impedance value.
Step 104: and if the first judgment result is negative, calculating the potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, the source current value and the pre-stored lightning current to obtain a first potential difference, and calculating the impulse impedance value based on the first potential difference. The pre-stored lightning current is a current signal measured before the current moment and during actual occurrence of lightning, and the current signal measured during the actual occurrence of each lightning is stored in the oscilloscope.
The method comprises the steps of calculating the potential Difference between every two points on the lightning arrester by adopting a Time-domain finite Difference (FDTD) method according to the radius of the lightning arrester, a source current value and a pre-stored lightning current to obtain a first potential Difference, and calculating the impulse impedance value based on the first potential Difference. As shown in fig. 2, the specific process of calculating the impulse impedance value by using the time-domain finite difference method is as follows:
1) from the radius R and source current value I of the arrestersourceCalculating the attenuation coefficient of the current flowing between every two points on the lightning arrester, and adopting pi,jAnd the attenuation coefficient of lightning current flowing between the ith point and the jth point on the lightning arrester is represented.
2) Calculating the potential difference between every two points on the lightning arrester by the attenuation coefficient to obtain a plurality of first potential differences, and adopting phi for any one first potential differencei,jIs represented by phii,jIs the potential difference between the point i and the point j on the arresteri,jIs formed by the corresponding pi,jAnd (4) calculating.
3) Calculating the potential difference of the lightning arrester by all the first potential differences to obtain a second potential difference, wherein the specific calculation formula is
Delta phi represents a second potential difference, N represents an FDTD program to divide the lightning arrester into N equal parts to obtain N +1 lightning arrester partsScattered data points, wherein i and j represent the labels of the scattered data points on the lightning arrester, wherein i is more than or equal to 1, j is more than or equal to N, i is not equal to j, phii+1,j+1Which represents the potential difference between the i +1 th point and the j +1 th point on the arrester.
4) And judging whether the second potential difference is smaller than a set potential value or not to obtain a second judgment result.
If the second judgment result is that the voltage deformation can be ignored, calculating the voltage, the current and the impulse impedance value of each point according to the potential of each point.
If the second judgment result is negative, the voltage deformation is larger, the pre-stored lightning current (the current measured when the actual lightning occurs) is used for replacing the source current value to update (modify) the attenuation coefficient until the second potential difference is smaller than the set potential value, and then the voltage, the current and the impulse impedance value of each point are calculated according to the corresponding first potential difference when the second potential difference is smaller than the set potential value. Before the current moment, the current measured when lightning actually occurs every time is stored in the oscilloscope in advance, so that the current measured when lightning actually occurs at different historical moments is adopted to replace the source current value during each iteration, the minimum voltage deformation is ensured, and the monitoring accuracy is improved.
After the shock resistance value is calculated through steps 103 and 104, the shock resistance value can be compared with a set safety value, and when the shock resistance value exceeds the set safety value, an alarm signal is sent out.
The invention also provides a device for monitoring the impulse impedance of the transformer substation arrester, and fig. 3 is a structural block diagram of the device for monitoring the impulse impedance of the transformer substation arrester provided by the embodiment of the invention.
Referring to fig. 3, the apparatus comprises:
the device comprises an atmospheric electric field measuring module, a main control computer and an impact impedance measuring device.
The main control computer is positioned in the control room; the impulse impedance measuring device is connected with the lightning arrester through a cable; and the main control computer is respectively connected with the atmospheric electric field measuring module and the impact impedance measuring device. And a Finite Difference Time Domain (FDTD) simulation program and a convolution transformation processing program are arranged in the master control computer.
The atmospheric electric field measurement module is used for: and measuring the electric field value of the high-altitude cloud layer.
The main control computer is used for:
and judging whether lightning is generated around the lightning arrester according to the high-altitude cloud layer electric field value, if so, sending a lightning coming permission signal to the impulse impedance measuring device, and if not, sending a blocking signal to the impulse impedance measuring device.
The surge impedance measuring device is used for:
after receiving the lightning coming permission signal, detecting a current signal flowing through the lightning arrester and voltage signals at two ends of the lightning arrester, and sending the current signal and the voltage signals to the main control computer;
and after receiving the blocking signal, converting the blocking signal into a real-time monitoring allowing signal, and sending the real-time monitoring allowing signal to the main control computer.
The master control computer is further configured to:
calculating a surge impedance value from the current signal and the voltage signal when lightning is to be generated around the lightning arrester;
when no lightning is generated around the lightning arrester, calculating potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, a source current value and pre-stored lightning current to obtain first potential difference, and calculating the impulse impedance value based on the first potential difference; the lightning current is a current signal measured when lightning actually occurs.
In one example, the surge impedance monitoring device for a substation arrester further comprises: indicator lights and alarm devices; the indicator light and the alarm equipment are positioned in the control room and are connected with the main control computer; the indicator light and alarm device is used for: and when the impact resistance value exceeds a set safety value, sending out an alarm signal. The alarm modules in the indicator light and the alarm device adopt audible and visual alarms so as to avoid being ignored.
In one example, the surge impedance monitoring device for a substation arrester further comprises: an oscilloscope; the oscilloscope is positioned in the control room and is connected with the main control computer; the oscilloscope is used for: storing the current signal and the voltage signal. The pre-stored lightning current is the current signal stored in the oscilloscope.
In one example, the surge impedance monitoring device for a substation arrester further comprises: the storage unit is positioned in the control room and is connected with the main control computer; the storage unit is used for: storing the surge impedance value.
In one example, referring to fig. 4, the atmospheric electric field measurement module may be an atmospheric electric field meter. The atmosphere electric field meter is used for detecting the electric field intensity of an atmosphere layer to obtain the electric field value of a high-altitude cloud layer, and measures the electric field by utilizing the principle that a conductor generates induced charges in the electric field. The main control computer judges whether lightning occurs according to the high-altitude cloud layer electric field value detected by the atmospheric electric field instrument, and if the lightning occurs, the impact impedance measuring device is locked.
In one example, referring to fig. 4, the main control computer is an industrial control computer with an Intel X86 platform, a convolution transformation processing program with built-in impulse impedance, an impulse reactance judgment program, and a Finite Difference Time Domain (FDTD) simulation program. The main control computer receives a user instruction; communicating with a surge current generator, controlling boosting and charging and discharging; communicating with an oscilloscope, controlling a sampling mode, storing, reading and processing waveform data and the like.
In one example, referring to fig. 4, the oscilloscope is the MAX70000 series, two-channel synchronous measurement; the frequency is 100 MHz; the storage process can be started by adopting an external triggering mode; 4000 points of data can be stored in each channel; the data bit width of a single point is 8 bits; the waveform data collected by the oscilloscope can be read by the external computer which is controlled by the external computer through the communication port.
In one example, referring to FIG. 4, a surge impedance measurement device collects a voltage response signal and transmits it to a counter during measurementA data processing system. The schematic circuit diagram of the impulse impedance measuring device is shown in fig. 5. R in FIG. 5IIs a current sampling resistor; r1、R2All are voltage sampling resistors; c1、C2All are frequency compensation capacitors; rP、RCA current electrode grounding resistor and a voltage electrode grounding resistor respectively; rDIs the impulse impedance of the arrester, which is to be measured. In the acquisition circuit, a current electrode C and a voltage electrode D respectively pass through a current electrode grounding resistor RCEarth resistance R of voltage electrodePIs connected to the top of the arrester. A current sampling resistor R is connected in series at the bottom of the lightning arresterIAnd the current sampling signal is conveniently led out through the cable. Parallel connection of two voltage sampling resistors R beside lightning arrester1、R2And a frequency compensation capacitor C1、C2And voltage sampling signals are conveniently led out through the cable.
In one example, referring to fig. 4, the surge impedance monitoring device for a substation arrester further includes: digital filters and communication devices.
One end of the digital filter is connected with the impulse impedance measuring device, and the other end of the digital filter is connected with the main control computer through the oscilloscope. The reason for choosing a digital filter is as follows: since the rogowski coil is generally used for measuring a high-frequency current or a large current, the measurement environment has large electromagnetic interference, and special attention is required for measurement. Therefore, in order to reduce the influence of the disturbance, a filter device for digital output is preferably used.
The communication equipment is connected with the main control computer, and the main control computer controls the FDTD simulation program through the communication equipment, sends a control signal to the impact impedance measuring device through the communication equipment and receives a signal of the atmospheric electric field instrument through the communication equipment.
The specific process for realizing real-time monitoring by adopting the transformer substation lightning arrester impact impedance monitoring device of the embodiment is as follows:
step 1: after the atmospheric electric field instrument monitors and collects the high-altitude cloud layer electric field value, the value is sent to a main control computer of a control room.
Step 2: and (3) comparing the value acquired in the step (1) with a threshold value (set electric field value) set in the system by the main control computer. If the high-altitude cloud layer electric field value in the step 1 is larger than the set electric field value, the lightning is generated around the lightning arrester, at the moment, the main control computer sends a lightning coming permission signal to the impulse impedance measuring device, and the impulse impedance measuring device receives the lightning coming permission signal and starts measuring. If the electric field value of the high-altitude cloud layer in the step 1 is smaller than or equal to the set electric field value, the fact that no lightning is generated around the lightning arrester means that no lightning is generated, and at the moment, the main control computer sends a locking signal to the impulse impedance measuring device and jumps to the step 5.
And step 3: and (3) after the impulse impedance measuring device receives the allowable signal in the step (2), the impulse impedance measuring device connected to the lightning arrester can measure a current signal flowing through the lightning arrester and a voltage signal at two ends of the lightning arrester.
And 4, step 4: and (4) sending the voltage signal and the current signal obtained in the step (3) to an oscilloscope of a control room. And the set operation program in the main control computer performs convolution conversion processing on the current signal and the voltage signal obtained in the step 3 so as to calculate the impulse impedance value of the lightning arrester, and the step 12 is skipped.
And 5: and (3) the main control computer sends the blocking signal obtained in the step (2) to the impulse impedance measuring device, the blocking signal is changed into a lightning coming permission signal through the inverter, and then the lightning coming permission signal is sent to FDTD simulation software in the main control computer.
Step 6: inputting the lightning coming permission signal obtained in the step 5 into an FDTD simulation program, so that the FDTD simulation program set in the main control computer starts to operate, and the data processing process is as shown in FIG. 2.
And 7: the radius R and the source current value I of the lightning arrester are input in an FDTD simulation program in advancesourceCalculating the attenuation coefficient p by program processingi,j。
And 8: attenuation coefficient p obtained in step 7i,jAfter FDTD simulation program processing, the potential difference phi of each point of the lightning arrester is obtainedi,j。
And step 9: the potential difference phi of each point of the lightning arrester obtained in the step 8i,jBy the formula
The processing results in a potential difference Δ Φ.
Step 10: the FDTD simulation program judges Δ Φ obtained in step 9, and if Δ Φ is not less than the set potential value, it means that the voltage distortion is large. The FDTD simulation program calls the current signal I in the oscilloscopesignalThe source current value I input in advance in step 7sourceIs replaced by IsignalAnd jumps back to step 7 and iterates until the condition is met and then proceeds to the subsequent step 12.
Step 11: the FDTD simulation program judges the delta phi obtained in the step 9, if the delta phi is less than the set potential value, the voltage deformation can be ignored, and the FDTD simulation program can directly pass through the potential difference phi of each point of the lightning arrester obtained in the step 8i,jThe voltage, current and surge resistance values of the arrester are calculated at each point and step 12 is performed.
Step 12: and after obtaining the impact impedance through the processing, the main control computer stores the impact impedance value into the storage unit and compares the impact impedance value with a set safety value, and sends a signal alarm to the alarm equipment when the impact impedance value exceeds the set safety value or the difference value between the impact impedance value and the set safety value exceeds a set safety range.
In the steps 5 to 11, the impact resistance value is calculated by using a model method, and compared with the traditional method of only multiplying the impact coefficient, the measurement is more accurate.
And 5-11, the device can not only temporarily measure the impulse impedance when the lightning comes, but also monitor the working condition of the lightning arrester in real time through simulation calculation.
Step 12, a storage unit is arranged, so that the impulse impedance of the lightning arrester can be recorded, and statistics is facilitated; the replacement plan of the lightning arrester is convenient to adjust.
The iterative updating mechanism in the step 10 enables the device to update and iterate the calculation model in real time according to the lightning voltage and lightning current surge impedance values measured under the real condition. The measurement result and the simulation result are verified mutually, so that the result is more accurate.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (10)
1. A transformer substation lightning arrester impact impedance monitoring method is characterized by comprising the following steps:
acquiring an electric field value of a high-altitude cloud layer;
judging whether lightning is generated around the lightning arrester or not according to the high-altitude cloud layer electric field value to obtain a first judgment result;
if the first judgment result is yes, acquiring a current signal flowing through the lightning arrester and voltage signals at two ends of the lightning arrester, and calculating an impulse impedance value according to the current signal and the voltage signals;
if the first judgment result is negative, calculating the potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, the source current value and the pre-stored lightning current to obtain a first potential difference, and calculating the impulse impedance value based on the first potential difference; the lightning current is a current signal measured when lightning actually occurs.
2. The surge impedance monitoring method for the substation lightning arrester according to claim 1, characterized by further comprising:
and comparing the impact resistance value with a set safety value, and sending an alarm signal when the impact resistance value exceeds the set safety value.
3. The method for monitoring the impulse impedance of the substation lightning arrester according to claim 1, wherein the step of calculating the potential difference between each two points on the lightning arrester according to the radius of the lightning arrester, the source current value and the pre-stored lightning current to obtain a first potential difference, and calculating the impulse impedance value based on the first potential difference specifically comprises the steps of:
and calculating the potential difference between every two points on the lightning arrester by adopting a time domain finite difference method according to the radius of the lightning arrester, the source current value and the pre-stored lightning current to obtain a first potential difference, and calculating the impulse impedance value based on the first potential difference.
4. The method for monitoring the impulse impedance of the substation arrester according to claim 3, wherein the step of calculating the potential difference between each two points on the arrester by using a time-domain finite difference method according to the radius of the arrester, the source current value and the pre-stored lightning current to obtain a first potential difference, and calculating the impulse impedance value based on the first potential difference specifically comprises:
calculating the attenuation coefficient of the current flowing between every two points on the lightning arrester according to the radius of the lightning arrester and the source current value;
calculating the potential difference between every two points on the lightning arrester according to the attenuation coefficient to obtain a plurality of first potential differences;
calculating the potential difference of the lightning arrester according to all the first potential differences to obtain a second potential difference;
judging whether the second potential difference is smaller than a set potential value or not to obtain a second judgment result;
if the second judgment result is yes, calculating an impact resistance value according to the first potential difference;
and if the second judgment result is negative, replacing the source current value with a pre-stored lightning current to update the attenuation coefficient until the second potential difference is smaller than the set potential value, and calculating the impulse impedance value corresponding to the first potential difference when the second potential difference is smaller than the set potential value.
5. The method for monitoring the surge impedance of the substation arrester according to claim 1, wherein the step of calculating the surge impedance value from the current signal and the voltage signal specifically comprises:
and carrying out convolution transformation processing on the current signal and the voltage signal to obtain an impulse impedance value.
6. The method for monitoring the impulse impedance of the substation lightning arrester according to claim 1, wherein the step of judging whether lightning is generated around the lightning arrester according to the high-altitude cloud-layer electric field value specifically comprises the steps of:
if the electric field value of the high-altitude cloud layer is larger than the set electric field value, determining that lightning is generated around the lightning arrester;
and if the electric field value of the high-altitude cloud layer is not greater than the set electric field value, determining that no lightning is generated around the lightning arrester.
7. The utility model provides a transformer substation's arrester surge impedance monitoring devices which characterized in that includes:
the system comprises an atmospheric electric field measuring module, a main control computer and an impact impedance measuring device;
the main control computer is positioned in the control room; the impulse impedance measuring device is connected with the lightning arrester; the main control computer is respectively connected with the atmospheric electric field measuring module and the impact impedance measuring device;
the atmospheric electric field measurement module is used for: measuring the electric field value of the high-altitude cloud layer;
the main control computer is used for:
judging whether lightning is generated around the lightning arrester according to the high-altitude cloud layer electric field value, if so, sending a lightning coming permission signal to the impulse impedance measuring device, and if not, sending a blocking signal to the impulse impedance measuring device;
the surge impedance measuring device is used for:
after receiving the lightning coming permission signal, detecting a current signal flowing through the lightning arrester and voltage signals at two ends of the lightning arrester, and sending the current signal and the voltage signals to the main control computer;
converting the locking signal into a real-time monitoring allowing signal after receiving the locking signal, and sending the real-time monitoring allowing signal to the main control computer;
the master control computer is further configured to:
calculating a surge impedance value from the current signal and the voltage signal when lightning is to be generated around the lightning arrester;
when no lightning is generated around the lightning arrester, calculating potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, a source current value and pre-stored lightning current to obtain first potential difference, and calculating the impulse impedance value based on the first potential difference; the lightning current is a current signal measured when lightning actually occurs.
8. The surge impedance monitoring device for the substation lightning arrester according to claim 7, characterized by further comprising: indicator lights and alarm devices; the indicator light and the alarm equipment are positioned in the control room and are connected with the main control computer;
the indicator light and alarm device is used for:
and when the impact resistance value exceeds a set safety value, sending out an alarm signal.
9. The surge impedance monitoring device for the substation lightning arrester according to claim 7, characterized by further comprising: an oscilloscope; the oscilloscope is positioned in the control room and is connected with the main control computer;
the oscilloscope is used for:
storing the current signal and the voltage signal.
10. The surge impedance monitoring device for the substation arrester according to claim 7, wherein a finite difference time domain simulation program and a convolution transformation processing program are embedded in the master control computer.
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