CN113138324B - Insulator flashover early warning system and method based on harmonic resonance monitoring quantity - Google Patents
Insulator flashover early warning system and method based on harmonic resonance monitoring quantity Download PDFInfo
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Abstract
The invention discloses an insulator flashover early warning system based on harmonic resonance monitoring quantity, which comprises a line charging capacitor power online monitoring unit, a power transmission line harmonic frequency monitoring unit and an insulator flashover critical condition early warning unit, wherein the insulator flashover critical condition early warning unit respectively receives signals from the line charging capacitor power online monitoring unit and the power transmission line harmonic frequency monitoring unit. The online monitoring unit for the power of the line charging capacitor and the harmonic frequency monitoring unit of the power transmission line transmit calculated data and collected data to the early warning unit for the flashover critical condition of the insulator, the early warning unit for the flashover critical condition of the insulator analyzes the data, and when the harmonic source frequency in the data, the combined equivalent reactance of the power transmission line and the charging capacitance value meet the harmonic resonance condition, the early warning unit for the flashover critical condition of the insulator transmits early warning information to the monitoring center of the power line, so that the effective monitoring and early warning of the insulation flashover condition in the power grid system are realized.
Description
Technical Field
The invention relates to the technical field of power grid system safety monitoring, in particular to an insulator flashover early warning system and method based on harmonic resonance monitoring amount.
Background
The insulator is an insulating device connected between a charged body and the ground, and plays an important potential isolation role between the overhead transmission line and the ground potential. During the operation of the overhead transmission line, dust, salt and alkali, industrial smoke and dust and other particles in the air or bird droppings are accumulated on the outer surface of the insulator to form a dirt layer. With the rapid development of economy in China, serious environmental pollution is brought at the same time. Generally, insulators which run on line are mostly in an atmospheric environment, a layer of filth is gradually deposited on the surface of the insulators, when wet weather occurs, the filth attached to the surface of the insulators is dissolved in water by soluble substances under the wet condition, and then a layer of conductive film is formed on the insulating surface, so that the insulating level of the insulators is greatly reduced, leakage current flows along the surface of the insulators, and the size of the flowing current mainly depends on the degree of filth and the degree of dampness. When the dirt and the damp are serious, the local electric arc can gradually develop and finally penetrates through the two electrodes to form dirt flashover.
The composite insulator flashover has a large influence on an electric power system, frequent accidents are flashover accidents of the composite insulator of the power transmission and transformation equipment under normal operating voltage, the research on the cause and significance of 'unclear flashover' of the composite insulator is significant, the existing emerging insulator pollution flashover early warning method adopts a leakage current online monitoring mode, the early warning mode carries out real-time online monitoring on flashover current one by one according to the characterization quantity of insulator flashover, but the early warning effect of the mode is limited, and the sudden accidents are difficult to be responded in advance only by monitoring the leakage current.
For example, chinese patent CN106093718A, published 2016, 11, 9, a method for warning flashover of an insulator, includes the following steps: (1) acquiring a salinity value of air; (2) determining the salt spray grade according to the salinity value obtained in the step (1); (3) acquiring a salt density value and an ash density value of the surface of the insulator; (4) determining the pollution grade of the insulator according to the salt density value and the ash density value of the surface of the insulator obtained in the step (3); (5) determining a dirt-moisture grade according to the salt spray grade obtained in the step (2) and the dirt grade obtained in the step (4); (6) and when the dirt-moisture level exceeds a preset threshold value, an insulator flashover alarm is sent out. The invention provides a dirt and moisture grade classification method based on the surface dirt accumulation of an insulator and the salt fog degree of air, which is used for evaluating the influence of the surface dirt accumulation of the insulator and the salt fog of ocean on external insulation, and further determining the configuration condition of the external insulation and the use condition of anti-pollution flashover measures according to the dirt and moisture grade. But the method has the problems that the method is difficult to respond to sudden accidents in advance only by monitoring the leakage current, and the early warning effect is limited.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the technical problem of limited early warning effect exists in the online leakage current monitoring mode adopted by the existing insulator flashover early warning method. The insulator flashover early warning system and method based on the harmonic resonance monitoring amount are capable of effectively monitoring and early warning the insulation flashover.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: an insulator flashover early warning system based on harmonic resonance monitoring amount comprises a line charging capacitor power online monitoring unit, a power transmission line harmonic frequency monitoring unit and an insulator flashover critical condition early warning unit, wherein the line charging capacitor power online monitoring unit and the power transmission line harmonic frequency monitoring unit are connected with a power transmission line, and the insulator flashover critical condition early warning unit respectively receives signals from the line charging capacitor power online monitoring unit and the power transmission line harmonic frequency monitoring unit. An insulator flashover early warning system based on harmonic resonance monitoring quantity comprises a line charging capacitor power online monitoring unit, a power transmission line harmonic frequency monitoring unit and an insulator flashover critical condition early warning unit, wherein the charging capacitance value of a power transmission line is monitored and calculated through the line charging capacitor power online monitoring unit and the power transmission line harmonic frequency monitoring unit, the harmonic frequency in the power transmission line is measured and collected through the power transmission line harmonic frequency monitoring unit, the calculated data and the collected data are transmitted to the insulator flashover critical condition early warning unit through the line charging capacitor power online monitoring unit and the power transmission line harmonic frequency monitoring unit, the insulator flashover critical condition early warning unit analyzes the data, and when the harmonic source frequency, the combined equivalent reactance of the power transmission line and the charging capacitance value in the data meet the harmonic resonance condition, the insulator flashover critical condition early warning unit sends early warning information to the power line monitoring center, and effective monitoring and early warning of the insulation flashover condition in the power grid system are achieved.
Preferably, the line charging capacitor power online monitoring unit comprises reactive power acquisition transmitters respectively positioned at two sides of the power transmission line, a plurality of rain and snow environment monitoring sensors for detecting environmental conditions of different positions of the power transmission line and a power differential computer, and the reactive power acquisition transmitters transmit acquired data of the power transmission line to the power differential computer. The reactive power acquisition transmitter is respectively positioned at two sides of the power transmission line, namely the head end and the tail end of the power transmission line, input signals of the reactive power acquisition transmitter are from a bus voltage transformer PT and a current transformer CT of the line, and the rain and snow environment monitoring sensor is used for setting rain and snow correction parameters according to the environment condition of the power transmission line.
Preferably, the power difference computer transmits data to the insulator flashover critical condition early warning unit. And the power difference computer calculates the difference value between the reactive power value at the head end of the line and the reactive power value at the tail end of the line to obtain the charging capacitance value of the line and sends the data to the early warning unit.
Preferably, each rain and snow day environment monitoring sensor wirelessly transmits data to the insulator flashover critical condition early warning unit. The rain and snow day environment monitoring sensor is arranged on an iron tower of a line, and transmits data to the early warning unit through wireless communication signals.
Preferably, the power transmission line harmonic frequency monitoring unit comprises harmonic frequency detection instruments respectively positioned at the head end and the tail end of the power transmission line, and the harmonic frequency detection instruments transmit the acquired power transmission line information to the insulator flashover critical condition early warning unit. The harmonic frequency monitoring unit of the power transmission line consists of harmonic frequency detecting instruments arranged at the head end and the tail end of the line, and the obtained information is sent to the early warning unit by the communication machine terminal.
Preferably, the insulator flashover critical condition early warning unit comprises an embedded computer and a communication terminal, and the communication terminal transmits the received data from the rain and snow day environment monitoring sensor, the harmonic frequency detection instrument and the power difference computer to the embedded computer. The insulator flashover critical condition early warning unit consists of an embedded computer and a communication terminal, after harmonic frequency is analyzed, the internal reactance of a harmonic source and the reactance of a transformer are calculated, after line reactance values are combined, the line reactance values and the charging power change track of a power transmission line are analyzed, when the overvoltage condition of harmonic resonance preset according to a change curve is reached, an output signal of insulator flashover early warning alarm is carried out, and the early warning signal is transmitted to a power line monitoring center.
An insulator flashover early warning method based on harmonic resonance monitoring quantity utilizes the insulator flashover early warning system, and comprises the following steps:
s1: monitoring the magnitude and the process of the change of the charging capacitance value of the power transmission line;
s2: measuring and collecting harmonic frequency in the power transmission line;
s3: analyzing the harmonic source frequency, the combined equivalent reactance of the power transmission line and the charging capacitance value by an insulator flashover critical condition early warning unit;
s4: and when the harmonic source frequency, the combined equivalent reactance of the power transmission line and the charging capacitance value meet the harmonic resonance condition, the insulator flashover critical condition early warning unit sends early warning information to the power line monitoring center. The method comprises the steps of monitoring the change size and process of a charging capacitor C of a circuit, measuring and collecting the harmonic frequency in a power transmission line, analyzing and calculating the parameters according to a harmonic resonance relational expression by a pre-warning unit, and when the harmonic source frequency f, the combined equivalent reactance L of the power transmission line and the charging capacitor C of the circuit meet the harmonic resonance condition, providing an alarm signal which is likely to generate harmonic resonance to attract the attention of a circuit management department, and taking corresponding action to prevent tripping accidents caused by flashover of insulators.
Preferably, the harmonic resonance condition includes a harmonic resonance relation, and the harmonic resonance relation is:
wherein f is the frequency of a harmonic source, L is the combined equivalent reactance of each point on the transmission line, and C is the charging equivalent capacitance of the transmission line.
Preferably, the step S1 includes the following steps:
s11: acquiring reactive power of the head end and the tail end of the power transmission line;
s12: determining a rainy and snowy day correction parameter according to a rainy and snowy day environment monitoring sensor;
s13: calculating the magnitude of the charging capacitance values of the power transmission lines at different moments;
s14: drawing a change curve of the charging capacitance value of the power transmission line according to the change of the value of the charging capacitance value of the power transmission line;
s15: and transmitting the calculation data to an insulator flashover critical condition early warning unit. The reactive power transducer measures the reactive magnitude of the two sides of the line, the charging power is Q1-Q2, and the charging capacitance value of the line can be calculated after the charging power Q1-Q2 of the line is subjected to differential calculation by the power differential computer.
Preferably, the step S2 includes the following steps:
s21: measuring and collecting the 3 rd, 5 th, 7 th, 9 th, 11 th, 13 th and 15 th harmonics of the power transmission line by a harmonic frequency detection instrument;
s22: and transmitting the collected harmonic frequency data in the power transmission line to an insulator flashover critical condition early warning unit. And transmitting the collected harmonic frequency to an insulator flashover critical condition early warning unit according to the harmonic component monitored in the harmonic monitor.
The substantial effects of the invention are as follows: the invention comprises a line charging capacitance power online monitoring unit, a power transmission line harmonic frequency monitoring unit and an insulator flashover critical condition early warning unit, wherein the charging capacitance value of the power transmission line is monitored and calculated by the line charging capacitance power online monitoring unit and the power transmission line harmonic frequency monitoring unit, the harmonic frequency in the power transmission line is measured and collected by the power transmission line harmonic frequency monitoring unit, the line charging capacitance power online monitoring unit and the power transmission line harmonic frequency monitoring unit transmit the calculated data and the collected data to the insulator flashover critical condition early warning unit, the insulator flashover critical condition early warning unit analyzes the data, and when the harmonic source frequency in the data, the combined equivalent reactance of the power transmission line and the charging capacitance value meet the harmonic resonance condition, the insulator flashover critical condition early warning unit transmits early warning information to a power line monitoring center, the method realizes effective monitoring and early warning of the insulation flashover condition in the power grid system.
Drawings
FIG. 1 is a schematic view of the overall structure of the present embodiment;
FIG. 2 is a schematic structural diagram of the present embodiment;
FIG. 3 is a flowchart illustrating steps performed in the present embodiment;
fig. 4 is a schematic configuration diagram of an anti-flashover risk early warning system according to the embodiment;
fig. 5 is a schematic structural diagram of a harmonic source interference system according to this embodiment;
fig. 6 is a schematic diagram of an equivalent circuit of the harmonic source of the present embodiment.
Wherein: 1. the device comprises a line charging capacitor power online monitoring unit, a power transmission line harmonic frequency monitoring unit, a 3 insulator flashover critical condition early warning unit, a 4 reactive power acquisition transmitter, a 5 rain and snow day environment monitoring sensor, a 6 power difference computer and a 7 harmonic frequency detecting instrument.
Detailed Description
The following provides a more detailed description of the present invention, with reference to the accompanying drawings.
The utility model provides an insulator flashover early warning system based on harmonic resonance monitoring volume, as shown in figure 1, including circuit charging capacitance power on-line monitoring unit 1, transmission line harmonic frequency monitoring unit 2 and insulator flashover critical condition early warning unit 3, circuit charging capacitance power on-line monitoring unit 1 and transmission line harmonic frequency monitoring unit 2 all are connected with transmission line, circuit charging capacitance power on-line monitoring unit 1 is including the reactive power collection changer 4 that is located transmission line both sides respectively, a plurality of rainy and snowy day environmental monitoring sensor 5 and the power difference computer 6 that are used for detecting the different position environmental conditions of transmission line, as shown in figure 2, reactive power collection changer 4 transmits the transmission line data of gathering for power difference computer 6. The reactive power acquisition transmitter 4 is respectively positioned at two sides of the power transmission line, namely the head end and the tail end of the power transmission line, input signals of the reactive power acquisition transmitter 4 are from a bus voltage transformer PT and a current transformer CT of the line, and the rain and snow environment monitoring sensor 5 is used for setting rain and snow correction parameters according to the environment condition of the power transmission line. And each rain and snow day environment monitoring sensor 5 wirelessly transmits data to the insulator flashover critical condition early warning unit 3. The rain and snow environment monitoring sensor 5 is arranged on an iron tower of a line, and transmits data to the early warning unit through wireless communication signals. And the power difference computer 6 transmits the data to the insulator flashover critical condition early warning unit 3. And the power difference computer 6 calculates the difference value between the reactive power value at the head end of the line and the reactive power value at the tail end of the line to obtain the charging capacitance value of the line and sends the data to the early warning unit.
The harmonic frequency monitoring unit 2 of the power transmission line comprises harmonic frequency detecting instruments 7 respectively positioned at the head end and the tail end of the power transmission line, and the harmonic frequency detecting instruments 7 transmit the acquired power transmission line information to the insulator flashover critical condition early warning unit 3. The harmonic frequency monitoring unit 2 of the power transmission line is composed of harmonic frequency detecting instruments 7 arranged at the head end and the tail end of the line, and sends acquired information to the early warning unit through a communication machine terminal.
The insulator flashover critical condition early warning unit 3 receives signals from the line charging capacitor power online monitoring unit 1 and the power transmission line harmonic frequency monitoring unit 2 respectively, the insulator flashover critical condition early warning unit 3 comprises an embedded computer and a communication terminal, and the communication terminal transmits received data from the rain and snow day environment monitoring sensor 5, the harmonic frequency detection instrument 7 and the power difference computer 6 to the embedded computer. The insulator flashover critical condition early warning unit 3 consists of an embedded computer and a communication terminal, after harmonic frequency is analyzed, the internal reactance of a harmonic source and the reactance of a transformer are calculated, after line reactance values are combined, the line reactance values and the charging power change track of a power transmission line are analyzed, when the overvoltage condition of harmonic resonance preset according to a change curve is achieved, an output signal of insulator flashover early warning alarm is carried out, and the early warning signal is transmitted to a power line monitoring center.
An insulator flashover early warning method based on harmonic resonance monitoring quantity is implemented by using the insulator flashover early warning system as shown in figure 3, and comprises the following steps:
s1: monitoring the magnitude and the process of the change of the charging capacitance value of the power transmission line; step S1 includes the following steps:
s11: acquiring reactive power of the head end and the tail end of the power transmission line;
s12: determining a rainy and snowy day correction parameter according to the rainy and snowy day environment monitoring sensor 5;
s13: calculating the magnitude of the charging capacitance values of the power transmission lines at different moments;
s14: drawing a change curve of the charging capacitance value of the power transmission line according to the numerical change of the charging capacitance value of the power transmission line;
s15: and transmitting the calculation data to an insulator flashover critical condition early warning unit 3. The reactive power transducer measures the reactive values of the two sides of the line, the charging power is Q1-Q2, and the charging capacitance value of the line can be calculated after the charging power Q of the line is Q1-Q2 is subjected to differential calculation by the power differential computer 6.
S2: measuring and collecting harmonic frequency in the power transmission line; step S2 includes the following steps:
s21: measuring and collecting the 3 rd, 5 th, 7 th, 9 th, 11 th, 13 th and 15 th harmonics of the power transmission line by a harmonic frequency detection instrument 7;
s22: and transmitting the collected harmonic frequency data in the power transmission line to an insulator flashover critical condition early warning unit 3. The collected harmonic frequency is transmitted to the insulator flashover critical condition early warning unit 3 according to the monitored harmonic component in the harmonic monitor, and the monitored harmonic component can be several of 3 rd, 5 th, 7 th, 9 th, 11 th, 13 th and 15 th harmonics in the power transmission line.
S3: analyzing the harmonic source frequency, the combined equivalent reactance of the power transmission line and the charging capacitance value through an insulator flashover critical condition early warning unit 3;
s4: when the harmonic source frequency, the combined equivalent reactance of the power transmission line and the charging capacitance value meet the harmonic resonance condition, the insulator flashover critical condition early warning unit 3 sends early warning information to the power line monitoring center. The harmonic resonance condition includes a harmonic resonance relation, which is:
wherein f is the frequency of a harmonic source, L is the combined equivalent reactance of each point on the power transmission line, and C is the charging equivalent capacitance of the power transmission line. The method comprises the steps of monitoring the change size and process of a charging capacitor C of a circuit, measuring and collecting harmonic frequency in a power transmission line, analyzing and calculating the parameters according to a harmonic resonance relational expression by an early warning unit, and when the harmonic source frequency f, the combined equivalent reactance L of the power transmission line and the charging capacitor C of the circuit meet the harmonic resonance condition, arranging an alarm signal which is likely to generate harmonic resonance so as to attract attention of a circuit management department, and taking corresponding action to prevent tripping accidents caused by flashover of insulators.
The method aims at finding the fault cause of 'unknown cause flashover' of the insulator of the power transmission line, and is a technical problem which is deposited for many years. The invention analyzes and monitors from the perspective of a harmonic theory of a power system, has the condition that the theory is consistent with the actual occurrence phenomenon, and sets a user D as a 5-11-order higher harmonic source En which has the interference capability of generating 5-order and 7-order harmonics in operation, as shown in figure 4, B2 is a step-down transformer of a 10kV terminal user substation, the voltage is in the 110kV/10kV grade, the line from A to B point is 110kV, the design length L is 60km, as shown in a system element parameter diagram of figure 5, and the method can be known after being converted to figure 6 of an equivalent electrical diagram: the harmonic source En forms a harmonic voltage to the charging equivalent capacitance C of the transmission line through the voltage reduction transformer B2The circuit is closed, and the charging capacitance value of the power transmission line can be regarded as an equivalent variable capacitor C to replace the power transmission line due to corona generation and dielectric constant change caused by rain. In practice, because the frequency range of the user harmonic source has uncertainty, and because the charging capacitor C in the line is a variable value, the requirement is met
In the formula, the L.C impedance is the lowest value, and the series resonance phenomenon occurs. The current in the loop will be very large when series resonance occurs, while at some point U in the line 2 Voltage value of U 2 ＝I hd X C ×. will become very high i.e. characteristic of harmonic overvoltages. When a certain point of this high overvoltage acts on the closest insulator on the line, an insulator flashover occurs. Because harmonic resonance overvoltage is a random phenomenon, the effect of measuring the leakage current of the insulator is not great, and simultaneously, a harmonic source and a charging capacitance value are changed, so that it is difficult to determine which specific point on a line can generate resonance overvoltage in operation, namely, the phenomenon of insulator flashover, which is a real theoretical reason of the phenomenon of insulator 'unknown flashover'.
The method for carrying out system monitoring on the parameters comprises the following steps: firstly, monitoring the change size and process of a charging capacitor C of a circuit; measuring and collecting harmonic frequency in the power transmission line; the early warning unit analyzes and calculates the parameters according to a harmonic resonance relational expression, and when the harmonic source frequency f and the combined equivalent reactance, the capacitive reactance, namely the inductance L and the capacitor C of each point on the circuit meet the harmonic resonance condition, an alarm signal which is possible to generate harmonic resonance is arranged to draw the attention of a circuit management department, and corresponding action is taken to prevent the tripping accident caused by flashover of the insulator.
The longer the length of the transmission line, the lower the amplification frequency of the harmonics generated by the harmonic source, i.e. the lower the resonance frequency. This is because the resonance condition between the line distributed capacitance Cn and the system reactance is satisfied, and the larger the parallel distributed capacitance value is, the lower the harmonic source resonance frequency is, that is, the condition of the harmonic resonance relational expression is satisfied.
The calculation process for harmonic resonance is as follows:
assuming that the transmission line is a 110kV line, the length of the line is 60kM, the type of the conducting wire is LGJ-240mm2, and the capacitance value is 0.904 mu F/110kM, namely C 0 0.0082 mu F/1kM, and the line reactance value is n L The resistance value R of the line is 0.391 Ω/1kM, 0.132 Ω/kM. Total capacitance C on the line 1 0.0082 × 60 ═ 0.492 μ f, step-down transformer B 2 Model SFS7-20000KVA/110kV, rated capacity 20000KVA, impedance voltage% high → low, U d 17.5%, reactance value n B2 78.7 Ω. Setting the voltage value of harmonic as 4% of rated voltage, U h ＝110kV×0.04＝4.4kV。
When the line length is 60kM, the variation parameter k of the capacitance increase in rainy days is calculated to be 2.8,
C 1 ＝0.492×2.8＝1.378μf，
when the harmonic source is a 5 th harmonic, f 5 5X 50 to 250Hz, and when the amplitude of 5 times is 4% of the fundamental wave, U 5 times (twice) ＝0.04×110kV＝4.4KV。
The inductance of the B2 transformer is: x B2 78.7 Ω 2 pi fL, 50Hz L0.25H, internal impedance of the harmonic source 0.06H, and total inductance L 1 0.25+0.06H 0.31H, and 1.3776 μ F for total capacitance C0.492 × 2.8.
And when the harmonic source is 5 th harmonic:
series harmonic frequencies under this condition:
to find
Point voltage value
U B-1 ＝i 5 times (twice) ·Xc，
U B-1 33.3kA × 462.3 Ω is 15384KV, which is 140 times higher than the rated voltage 110KV, and such a high voltage value tends to immediately breakdown and discharge the insulator at the point. From the above calculation, it is understood that the resonant overvoltage due to the harmonic is one of the main and common causes of the insulator "unknown flashover", and as the line is on a clear day, the resonant frequency oscillates in the direction of higher order waves due to the decrease in the capacitance value C, and the oscillation starting condition is related to the frequency of the harmonic source.
When a harmonic source is set to be 7 harmonics, the capacitance is reduced when the weather is clear, and when the correction parameter k in rainy and snowy days is set to be 1.35 times, the charging capacitance C in the line is set 2 ＝0.442×1.35＝0.664
under the condition of fine weather, if harmonic interference exists in the electric load at the moment, namely, a harmonic source of 7 times exists, a resonance overvoltage situation of 7 times of harmonic waves can be generated, and the generated high voltage value is also a fault accident that insulation flashover can occur.
From the above, since the capacitor on the line is actually an equivalent variable capacitor C in the rainy weather condition, in this case, if the user has many times rich harmonic sources, the root isAccording to frequency and L, C
It is very likely that when a proper capacitance value exists, the inductor and the frequency of a harmonic source of a user can meet a harmonic resonance condition, so that resonance overvoltage is very easy to occur, and the fault of insulator flashover occurs, which is the true reason for 'unknown flashover' of a large number of insulators.
The embodiment comprises a line charging capacitor power online monitoring unit 1, a power transmission line harmonic frequency monitoring unit 2 and an insulator flashover critical condition early warning unit 3, wherein the charging capacitance value of the power transmission line is monitored and calculated by the line charging capacitor power online monitoring unit 1 and the power transmission line harmonic frequency monitoring unit 2, the harmonic frequency in the power transmission line is measured and collected by the power transmission line harmonic frequency monitoring unit 2, the line charging capacitor power online monitoring unit 1 and the power transmission line harmonic frequency monitoring unit 2 transmit the calculated data and the collected data to the insulator flashover critical condition early warning unit 3, the insulator flashover critical condition early warning unit 3 analyzes the data, and when the harmonic source frequency in the data, the combined equivalent reactance of the power transmission line and the charging capacitance value meet the harmonic resonance condition, the insulator flashover critical condition early warning unit 3 sends early warning information to a power line monitoring center, the method realizes effective monitoring and early warning of the insulation flashover condition in the power grid system.
The above examples only show several embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
Claims (9)
1. An insulator flashover early warning system based on harmonic resonance monitoring quantity is characterized by comprising a line charging capacitor power online monitoring unit (1), a power transmission line harmonic frequency monitoring unit (2) and an insulator flashover critical condition early warning unit (3), wherein the line charging capacitor power online monitoring unit (1) and the power transmission line harmonic frequency monitoring unit (2) are connected with a power transmission line, and the insulator flashover critical condition early warning unit (3) receives signals from the line charging capacitor power online monitoring unit (1) and the power transmission line harmonic frequency monitoring unit (2) respectively;
the line charging capacitor power online monitoring unit (1) comprises reactive power acquisition transmitters (4) respectively located on two sides of a power transmission line, a plurality of rain and snow environment monitoring sensors (5) used for detecting environmental conditions of different positions of the power transmission line and a power differential computer (6), wherein the reactive power acquisition transmitters (4) transmit acquired power transmission line data to the power differential computer (6).
2. The insulator flashover early warning system based on harmonic resonance monitoring amount according to claim 1, characterized in that the power difference computer (6) transmits data to the insulator flashover critical condition early warning unit (3).
3. The insulator flashover early warning system based on harmonic resonance monitoring amount according to claim 1, characterized in that each of the rain and snow day environment monitoring sensors (5) wirelessly transmits data to the insulator flashover critical condition early warning unit (3).
4. The insulator flashover early warning system based on the harmonic resonance monitoring amount according to claim 1, characterized in that the power transmission line harmonic frequency monitoring unit (2) comprises harmonic frequency detection instruments (7) respectively positioned at the head end and the tail end of the power transmission line, and the harmonic frequency detection instruments (7) transmit the acquired power transmission line information to the insulator flashover critical condition early warning unit (3).
5. The insulator flashover early warning system based on harmonic resonance monitoring amount according to claim 4, characterized in that the insulator flashover critical condition early warning unit (3) comprises an embedded computer and a communication terminal, and the communication terminal transmits received data from the rain and snow environment monitoring sensor (5), the harmonic frequency detection instrument (7) and the power difference computer (6) to the embedded computer.
6. An insulator flashover early warning method based on harmonic resonance monitoring quantity, which utilizes the insulator flashover early warning system based on harmonic resonance monitoring quantity as claimed in any one of claims 1-5, and is characterized by comprising the following steps:
s1: monitoring the magnitude and the process of the change of the charging capacitance value of the power transmission line;
s2: measuring and collecting harmonic frequency in the power transmission line;
s3: analyzing the harmonic source frequency, the combined equivalent reactance of the power transmission line and the charging capacitance value through an insulator flashover critical condition early warning unit (3);
s4: when the harmonic source frequency, the combined equivalent reactance of the power transmission line and the charging capacitance value meet the harmonic resonance condition, the insulator flashover critical condition early warning unit (3) sends early warning information to the power line monitoring center.
7. The insulator flashover early warning method based on the harmonic resonance monitoring quantity according to claim 6, wherein the harmonic resonance condition comprises a harmonic resonance relational expression which is as follows:
wherein f is the frequency of a harmonic source, L is the combined equivalent reactance of each point on the transmission line, and C is the charging equivalent capacitance of the transmission line.
8. The insulator flashover early warning method based on harmonic resonance monitoring amount according to claim 6, wherein the S1 comprises the following steps:
s11: acquiring reactive power of the head end and the tail end of the power transmission line;
s12: determining a rainy and snowy day correction parameter according to a rainy and snowy day environment monitoring sensor (5);
s13: calculating the magnitude of the charging capacitance values of the power transmission lines at different moments;
s14: drawing a change curve of the charging capacitance value of the power transmission line according to the numerical change of the charging capacitance value of the power transmission line;
s15: and transmitting the calculation data to an insulator flashover critical condition early warning unit (3).
9. The insulator flashover early warning method based on the harmonic resonance monitoring amount as claimed in claim 6, wherein the S2 comprises the following steps:
s21: measuring and collecting the 3 rd, 5 th, 7 th, 9 th, 11 th, 13 th and 15 th harmonics of the power transmission line by a harmonic frequency detection instrument (7);
s22: and transmitting the collected harmonic frequency data in the power transmission line to an insulator flashover critical condition early warning unit (3).
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| CN117368797B (en) * | 2023-11-17 | 2024-08-13 | 国网青海省电力公司海南供电公司 | Composite insulator flashover early warning method based on leakage current and power field analysis |
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| JPS5269366A (en) * | 1975-12-06 | 1977-06-09 | Fuji Electric Co Ltd | Flash over tester |
| JP3389063B2 (en) * | 1997-06-16 | 2003-03-24 | 古河電気工業株式会社 | Power cable deterioration diagnosis method |
| CN101929972A (en) * | 2010-07-08 | 2010-12-29 | 吕强 | Insulator contamination on-line monitoring system |
| CN102508036B (en) * | 2011-11-02 | 2014-07-16 | 浙江大学城市学院 | On-line remote monitoring method and device for pollution state of disk insulator |
| CN103675434A (en) * | 2013-12-12 | 2014-03-26 | 国家电网公司 | System and method for early warning insulator pollution flashover |
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