CN113608031B - Impact impedance monitoring method and device for substation lightning arrester - Google Patents
Impact impedance monitoring method and device for substation lightning arrester Download PDFInfo
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Abstract
The invention discloses a method and a device for monitoring impact impedance of a substation 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 electric field value of the high-altitude cloud layer; if lightning is generated, acquiring a current signal flowing through the lightning arrester and a voltage signal at two ends of the lightning arrester, and calculating an impulse impedance value according to the current signal and the voltage signal; 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 prestored 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 surge 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 impact impedance of a substation lightning arrester.
Background
The transformer substation is a hub of a power system, once lightning stroke damages equipment accidents, large-area power failure is caused, and the internal insulation of high-voltage electric equipment such as a transformer is not self-recovered, so that the equipment is very difficult to repair after being damaged by the lightning stroke, the power failure is caused for a long time, the equipment is damaged, the direct loss of power supply is caused, and the national economy and the life of people are seriously influenced. Therefore, the measurement of the impact impedance of the lightning arrester in the construction of the transformer substation is an indispensable link, and the measurement and analysis of the impact impedance of the lightning arrester equipment of the transformer substation can enable the protection of the transformer substation to be more reliable. Generally, the surge impedance is the ground impedance presented by the ground body under lightning current surge.
The impact impedance of the lightning arrester in the power station lightning protection device is an important parameter for the design of a transformer substation and ensuring the normal operation of the transformer substation, and is very necessary to accurately measure the impact impedance, and the following points are mainly shown: 1. and measuring the real grounding impedance of the grounding device, checking whether the grounding impedance of the new grounding grid meets the design requirement, and checking whether the grounding impedance of the old grounding grid changes. 2. And checking the calculated value to check the correctness of the calculation method, and providing basis for new calculation methods or software popularization and application. 3. The ground potential rise due to the power system ground fault current and the potential change throughout the phase are determined. 4. And determining the suitability of the lightning protection grounding device. 5. And obtaining design data necessary for lightning protection of the transformer substation, lightning protection of equipment and related personal safety.
With the development of power systems, the scale of the power grid is continuously expanded, various microcomputer monitoring devices are widely applied, and the impact impedance can be accurately measured, so that the real-time monitoring of the impact impedance of the grounding device is a current requirement. However, at present, impulse impedance can only be measured under a power frequency condition or when lightning comes, and real-time monitoring cannot be performed on impulse impedance of a lightning arrester, so that safety detection of a transformer substation is insufficient, and reliability of protection of the transformer substation is still to be improved.
Disclosure of Invention
Based on the above, the embodiment of the invention provides a method and a device for monitoring impulse impedance of a substation arrester, which can monitor the impulse impedance of the arrester when lightning current is temporarily used, and can monitor the impulse impedance of the arrester when no lightning is generated, thereby realizing real-time monitoring of the impulse impedance of the arrester and further improving the reliability of substation protection.
In order to achieve the above object, the present invention provides the following solutions:
a method for monitoring surge impedance of a substation arrester, comprising:
acquiring an electric field value of a high-altitude cloud layer;
judging whether lightning is generated around the lightning arrester according to the high-altitude cloud layer electric field value, and obtaining a first judgment result;
if the first judgment result is yes, acquiring a current signal flowing through the lightning arrester and a voltage signal at two ends of the lightning arrester, and calculating an impact impedance value according to the current signal and the voltage signal;
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, a source current value and a prestored 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 impact impedance of the substation lightning arrester further includes:
comparing the impact impedance value with a set safety value, and sending out an alarm signal when the impact impedance value exceeds the set safety value.
Optionally, the 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 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, a source current value and a prestored 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 first potential difference from a radius of the lightning arrester, a source current value and a pre-stored lightning current, and calculating the impulse impedance value based on the first potential difference, 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 from 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 impedance value by the first potential difference;
if the second judgment result is negative, replacing the source current value by the prestored 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 the impulse impedance value from the current signal and the voltage signal specifically includes:
and performing convolution transformation processing on the current signal and the voltage signal to obtain an impulse impedance value.
Optionally, the determining, by the high altitude cloud layer electric field value, whether lightning will occur 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 larger 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 impact impedance of the substation lightning arrester, which comprises the following components:
the system comprises an atmospheric electric field measurement module, a main control computer and an impact impedance measurement device;
the main control computer is positioned in the control room; the impact impedance measuring device is connected with the lightning arrester; the main control computer is respectively connected with the atmospheric electric field measurement module and the impact impedance measurement 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 impact impedance measuring device is used for:
detecting a current signal flowing through the lightning arrester and a voltage signal at two ends of the lightning arrester after receiving the lightning coming permission signal, and sending the current signal and the voltage signal to the main control computer;
when the locking signal is received, converting the locking signal into a real-time monitoring permission signal, and sending the real-time monitoring permission signal to the main control computer;
the main control computer is also used for:
calculating a surge impedance value from the current signal and the voltage signal when lightning will occur around the arrester;
when no lightning is generated around the lightning arrester, calculating the potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, a source current value and a prestored 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 transformer substation lightning arrester impact impedance monitoring device further includes: the indication lamp and the alarm device; the indicator light and the alarm device are positioned in the control room and connected with the main control computer;
the indicator light and the alarm device are used for:
and when the impact impedance value exceeds a set safety value, an alarm signal is sent out.
Optionally, the transformer substation lightning arrester impact impedance monitoring device further includes: an oscilloscope; the oscilloscope is positioned in the control room and connected with the main control computer;
the oscilloscope is used for:
the current signal and the voltage signal are stored.
Optionally, the master control computer is internally provided with a time domain finite difference simulation program and a convolution transformation processing program.
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 substation arrester, wherein the method comprises the steps of firstly judging whether lightning is generated around the arrester according to an electric field value of a high-altitude cloud layer; if lightning is generated, acquiring a current signal flowing through the lightning arrester and a voltage signal at two ends of the lightning arrester, and calculating an impulse impedance value according to the current signal and the voltage signal; if no lightning is generated, the potential difference between every two points on the lightning arrester is calculated according to the radius of the lightning arrester, the source current value and the pre-stored lightning current, and the impulse impedance value is calculated based on the potential difference between every two points on the lightning arrester. According to the invention, when lightning is generated, the surge impedance of the lightning arrester can be monitored, so that the surge impedance of the lightning arrester is monitored in real time, and the reliability of transformer substation protection is improved.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a flowchart of a method for monitoring impact impedance of a substation arrester according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of calculating an impact impedance value by using a finite difference method in a time domain according to an embodiment of the present invention;
fig. 3 is a block diagram of a transformer substation lightning arrester impact impedance monitoring device 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 substation arrester according to an embodiment of the present invention;
fig. 5 is a schematic circuit diagram of an impact impedance measurement device according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Fig. 1 is a flowchart of a method for monitoring impact impedance of a substation arrester according to an embodiment of the present invention. Referring to fig. 1, the method for monitoring impact impedance of a substation arrester according to the embodiment includes:
step 101: and obtaining the electric field value of the high-altitude cloud layer.
Step 102: and judging whether lightning is generated around the lightning arrester according to the electric field value of the high-altitude cloud layer, and obtaining 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 larger 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 a voltage signal at two ends of the lightning arrester, and calculating an impact impedance value according to the current signal and the voltage signal.
The impulse impedance value is calculated by the current signal and the voltage signal, specifically: and performing convolution transformation processing on the current signal and the voltage signal to obtain an impulse impedance value.
Step 104: 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 prestored lightning current to obtain a first potential difference, and calculating the impulse impedance value based on the first potential difference. The lightning current stored in advance is a current signal measured when lightning actually occurs before the current moment, and each current signal measured when lightning actually occurs is stored in the oscilloscope.
The method comprises the steps of calculating the potential difference between every two points on the lightning arrester by using a Time-domain finite difference (Time-DomainFinite Difference, FDTD) method according to the radius of the lightning arrester, a source current value and a prestored lightning current, obtaining 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 impact impedance value by using the time domain finite difference method is as follows:
1) From the radius R and the source current value I of the lightning arrester source Calculating attenuation coefficient of current flowing between every two points on the lightning arrester by using p i,j The attenuation coefficient of the lightning current flowing between the i-th point and the j-th point on the lightning arrester is shown.
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, wherein phi is adopted for any one first potential difference i,j Represent phi i,j Is the potential difference between the ith point and the jth point on the lightning arrester, phi i,j Is formed by corresponding p i,j Calculated.
3) Calculating the potential difference of the lightning arrester from all the first potential differences to obtain a second potential difference, wherein a specific calculation formula is as follows
ΔΦ represents the second potential difference, N represents the FDTD program dividing the arrester into N equal parts to obtain N+1 discrete data points, wherein i, j represents the label of the discrete data points on the arrester, wherein 1.ltoreq.i, j.ltoreq.N, i.noteq, Φ i+1,j+1 Indicating the potential difference between the i+1th point and the j+1th 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 yes, the voltage deformation is negligible, and the voltage, the current and the impact impedance value of each point are calculated according to the potential of each point.
If the second judgment result is negative, indicating that the voltage deformation is large, replacing the source current value with a prestored lightning current (current measured when actual lightning occurs) to update (modify) the attenuation coefficient until the second potential difference is smaller than the set potential value, and calculating the voltage, current and impact impedance value of each point according to each 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 each 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 current value of the source each time of iteration, the voltage deformation is guaranteed to be minimum, and the monitoring accuracy is improved.
After the impact impedance value is calculated in the steps 103 and 104, the impact impedance value can be compared with a set safety value, and when the impact impedance value exceeds the set safety value, an alarm signal is sent out.
The invention further provides a transformer substation lightning arrester impact impedance monitoring device, and fig. 3 is a structural block diagram of the transformer substation lightning arrester impact impedance monitoring device.
Referring to fig. 3, the apparatus includes:
the system comprises an atmospheric electric field measurement module, a main control computer and an impact impedance measurement device.
The main control computer is positioned in the control room; the impact impedance measuring device is connected with the lightning arrester through a cable; the main control computer is respectively connected with the atmospheric electric field measuring module and the impact impedance measuring device. The main control computer is internally provided with a time domain finite difference (FDTD) simulation program and a convolution transformation processing program.
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:
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 impact impedance measuring device is used for:
detecting a current signal flowing through the lightning arrester and a voltage signal at two ends of the lightning arrester after receiving the lightning coming permission signal, and sending the current signal and the voltage signal to the main control computer;
and when the locking signal is received, converting the locking signal into a real-time monitoring permission signal, and sending the real-time monitoring permission signal to the main control computer.
The main control computer is also used for:
calculating a surge impedance value from the current signal and the voltage signal when lightning will occur around the arrester;
when no lightning is generated around the lightning arrester, calculating the potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, a source current value and a prestored 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.
In one example, the substation arrester surge impedance monitoring device further includes: the indication lamp and the alarm device; the indicator light and the alarm device are positioned in the control room and connected with the main control computer; the indicator light and the alarm device are used for: and when the impact impedance value exceeds a set safety value, an alarm signal is sent out. The indicator lamp and the alarm module in the alarm device adopt audible and visual alarms so as to avoid being ignored.
In one example, the substation arrester surge impedance monitoring device further includes: an oscilloscope; the oscilloscope is positioned in the control room and connected with the main control computer; the oscilloscope is used for: the current signal and the voltage signal are stored. The lightning current stored in advance is a current signal stored in the oscilloscope.
In one example, the substation arrester surge impedance monitoring device further includes: the storage unit is positioned in the control room and connected with the main control computer; the storage unit is used for: storing the impact resistance value.
In one example, referring to fig. 4, the atmospheric electric field measurement module may be an atmospheric electric field meter. The atmospheric electric field instrument is used for detecting the atmospheric electric field intensity to obtain the electric field value of the high-altitude cloud layer, and the electric field is measured by utilizing the principle that a conductor generates induced charges in the electric field. And 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 impulse impedance measuring device is locked.
In one example, referring to fig. 4, the host computer is an industrial personal computer with Intel X86 as a platform, and a convolution transformation processing program of built-in impact impedance, an impact reactance judging program, and a Finite Difference Time (FDTD) simulation program are used. The main control computer receives a user instruction; the device is communicated with the impulse current generator, and controls the boosting, 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, an oscilloscope is the MAX70000 series, two channel synchronous measurement; the frequency is 100MHz; an external triggering mode can be adopted to start a storage process; 4000 points of data can be stored per channel; the data bit width of a single point is 8 bits; the waveform data acquired by the oscillograph can be read by an external computer through the communication port.
In one example, referring to FIG. 4, the impulse impedance measurement device, when measuring, collects a voltage response signal and transmits it to the data processing system. A schematic circuit diagram of the impact impedance measuring device is shown in fig. 5. R in FIG. 5 I The current sampling resistor is adopted; r is R 1 、R 2 All are voltage sampling resistors; c (C) 1 、C 2 Are all frequency compensation capacitors; r is R P 、R C The current electrode grounding resistor and the voltage electrode grounding resistor are respectively arranged; r is R D The surge impedance of the lightning arrester is the surge impedance to be measured. In the acquisition circuit, a current pole C and a voltage pole D are respectively connected with a grounding resistor R through the current pole C Grounding resistor R of voltage pole P Is connected to the top of the arrester. The bottom of the lightning arrester is connected in series with a current sampling resistor R I The current sampling signal is conveniently led out through the cable. Two parallel voltage sampling resistors R beside lightning arrester 1 、R 2 Frequency compensation capacitor C 1 、C 2 The voltage sampling signal is conveniently led out through the cable.
In one example, referring to fig. 4, the substation arrester impact impedance monitoring device further includes: a digital filter and a communication device.
One end of the digital filter is connected with the impact impedance measuring device, and the other end of the digital filter is connected with the main control computer through an oscilloscope. The reason for selecting the digital filter is as follows: since the rogowski coil is generally used for measuring a high frequency current or a large current, a measuring environment has a large electromagnetic interference, and special attention is required for measurement. Therefore, in order to reduce the influence of interference, a filter device for digital output is preferable.
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 control signals to the impact impedance measuring device through the communication equipment and receives signals of the atmospheric electric field instrument through the communication equipment.
The specific process of realizing real-time monitoring by adopting the impact impedance monitoring device of the substation lightning arrester of the embodiment is as follows:
step 1: and after the atmospheric electric field instrument monitors and collects the electric field value of the high-altitude cloud layer, the electric field value is sent to a main control computer of the control room.
Step 2: and (3) comparing the numerical 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 electric field value of the high-altitude cloud layer in the step 1 is larger than the set electric field value, the fact that lightning is generated around the lightning arrester means that the lightning is generated, 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 to start measuring work. 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 is indicated, and at the moment, the main control computer sends a locking signal to the impulse impedance measuring device and jumps to the step 5.
Step 3: after the impulse impedance measuring device receives the permission signal in the step 2, the impulse impedance measuring device connected to the lightning arrester can measure the current signal flowing through the lightning arrester and the voltage signal at two ends of the lightning arrester.
Step 4: the voltage signal and the current signal obtained in the step 3 are sent to an oscilloscope of a control room. And the operation program set in the main control computer carries out convolution conversion processing on the current signal and the voltage signal obtained in the step 3 so as to calculate and obtain the impact impedance value of the lightning arrester, and the step 12 is skipped.
Step 5: the main control computer sends the locking signal obtained in the step 2 to the impulse impedance measuring device, the locking signal is changed into a lightning incoming permission signal through the phase inverter, and then the lightning incoming permission signal is sent to FDTD simulation software in the main control computer.
Step 6: and 5, inputting the lightning coming permission signal obtained in the step into the FDTD simulation program, so that the FDTD simulation program set in the main control computer starts to run, and the data processing process is shown in figure 2.
Step 7: simulation program in FDTDThe radius R and the source current value I of the lightning arrester are input in advance source The attenuation coefficient p is obtained through program processing and calculation i,j 。
Step 8: the attenuation coefficient p obtained in step 7 i,j After being processed by FDTD simulation program, the potential difference phi of each point of the lightning arrester is obtained i,j 。
Step 9: the potential difference phi of each point of the lightning arrester obtained in the step 8 i,j Using the formulaThe processing results in a potential difference delta phi.
Step 10: and (3) judging the delta phi obtained in the step (9) by the FDTD simulation program, wherein if the delta phi is more than or equal to the set potential value, the voltage deformation is larger. Then the FDTD simulation program invokes the current signal I in the oscilloscope signal The source current value I input in step 7 in advance is calculated source Replaced by I signal And jumping back to the step 7, iterating until the condition is met, and then carrying out the subsequent step 12.
Step 11: the FDTD simulation program judges the delta phi obtained in the step 9, if delta phi is less than the set potential value, the voltage deformation is negligible, and the FDTD simulation program can directly pass through the potential difference phi of each point of the lightning arrester obtained in the step 8 i,j To calculate the voltage, current and surge impedance values of the lightning arrester at each point and to proceed to step 12.
Step 12: after the main control computer obtains the impact impedance through the processing, the impact impedance value is stored in the storage unit and is compared with the set safety value, and 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 the set safety range, a signal is sent to alarm equipment for alarm.
And step 5 to step 11 calculate the impulse impedance value by using a model method, and compared with the traditional mode of only multiplying the impulse coefficient, the method has more accurate measurement.
Step 5-step 11 make the device not only can be in the lightning coming the impulse impedance of real-time measurement, can also pass through simulation calculation real-time monitoring arrester operating mode.
Step 12 is provided with a storage unit, and the impact impedance of the lightning arrester can be recorded, so that statistics is convenient; and the replacement plan of the lightning arrester is convenient to adjust.
The iterative updating mechanism of the step 10 enables the device to update and iterate the calculation model in real time according to the lightning voltage and lightning current impulse impedance values measured in real conditions. The measurement result and the simulation result are mutually verified, so that the result is more accurate.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (8)
1. The method for monitoring the impact impedance of the substation lightning arrester is characterized by comprising the following steps of:
acquiring an electric field value of a high-altitude cloud layer;
judging whether lightning is generated around the lightning arrester according to the high-altitude cloud layer electric field value, and obtaining a first judgment result;
if the first judgment result is yes, acquiring a current signal flowing through the lightning arrester and a voltage signal at two ends of the lightning arrester, and calculating an impact impedance value according to the current signal and the voltage signal;
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, a source current value and a prestored 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;
calculating the potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, a source current value and a prestored lightning current to obtain a first potential difference, and calculating the impact impedance value based on the first potential difference, wherein the method specifically comprises the following steps:
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, a source current value and a prestored lightning current to obtain a first potential difference, and calculating the impulse impedance value based on the first potential difference, wherein the method specifically comprises the following steps of:
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 from 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 impedance value by the first potential difference;
if the second judgment result is negative, replacing the source current value by the prestored 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.
2. The method for monitoring surge impedance of a substation arrester of claim 1, further comprising:
comparing the impact impedance value with a set safety value, and sending out an alarm signal when the impact impedance value exceeds the set safety value.
3. 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 comprises the following steps:
and performing convolution transformation processing on the current signal and the voltage signal to obtain an impulse impedance value.
4. The method for monitoring impulse impedance of a substation arrester according to claim 1, wherein the determining whether lightning will occur around the arrester according to the electric field value of the high-altitude cloud layer specifically comprises:
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 larger than the set electric field value, determining that no lightning is generated around the lightning arrester.
5. A substation arrester surge impedance monitoring device, comprising:
the system comprises an atmospheric electric field measurement module, a main control computer and an impact impedance measurement device;
the main control computer is positioned in the control room; the impact impedance measuring device is connected with the lightning arrester; the main control computer is respectively connected with the atmospheric electric field measurement module and the impact impedance measurement 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 impact impedance measuring device is used for:
detecting a current signal flowing through the lightning arrester and a voltage signal at two ends of the lightning arrester after receiving the lightning coming permission signal, and sending the current signal and the voltage signal to the main control computer;
when the locking signal is received, converting the locking signal into a real-time monitoring permission signal, and sending the real-time monitoring permission signal to the main control computer;
the main control computer is also used for:
calculating a surge impedance value from the current signal and the voltage signal when lightning will occur around the arrester;
when no lightning is generated around the lightning arrester, calculating the potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, a source current value and a prestored 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;
calculating the potential difference between every two points on the lightning arrester according to the radius of the lightning arrester, a source current value and a prestored lightning current to obtain a first potential difference, and calculating the impact impedance value based on the first potential difference, wherein the method specifically comprises the following steps:
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, a source current value and a prestored lightning current to obtain a first potential difference, and calculating the impulse impedance value based on the first potential difference, wherein the method specifically comprises the following steps of:
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 from 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 impedance value by the first potential difference;
if the second judgment result is negative, replacing the source current value by the prestored 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.
6. The surge impedance monitoring device of the substation arrester of claim 5, further comprising: the indication lamp and the alarm device; the indicator light and the alarm device are positioned in the control room and connected with the main control computer;
the indicator light and the alarm device are used for:
and when the impact impedance value exceeds a set safety value, an alarm signal is sent out.
7. The surge impedance monitoring device of the substation arrester of claim 5, further comprising: an oscilloscope; the oscilloscope is positioned in the control room and connected with the main control computer;
the oscilloscope is used for:
the current signal and the voltage signal are stored.
8. The surge impedance monitoring device for the substation arrester according to claim 5, wherein the main control computer is internally provided with a time domain finite difference simulation program and a convolution transformation processing program.
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