CN109596948B - Distribution line insulation state evaluation method - Google Patents
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- CN109596948B CN109596948B CN201811508614.5A CN201811508614A CN109596948B CN 109596948 B CN109596948 B CN 109596948B CN 201811508614 A CN201811508614 A CN 201811508614A CN 109596948 B CN109596948 B CN 109596948B
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
- G01R31/1272—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
Abstract
The application discloses a distribution line insulation state evaluation method, which comprises the steps of firstly, establishing a distribution line insulation state evaluation model according to in-area, out-area and unset fault information and distribution line operation conditions; secondly, when an insulation fault occurs, determining the value of the distribution line insulation state evaluation index according to the recording data of each monitoring point; and finally, according to the value of the distribution line insulation state evaluation index, evaluating the insulation state of each section of the distribution line by using a distribution line insulation state evaluation model. Through the method and the device, the accuracy and the reliability of the distribution line insulation state evaluation can be improved, the alarm signal can be timely given when the insulation state is reduced to a certain degree, the insulation state of the distribution line can be timely known, a basis is provided for line state maintenance, and the reliability of the distribution line is further improved.
Description
Technical Field
The application relates to the technical field of power transmission and distribution, in particular to a distribution line insulation state evaluation method.
Background
In the technical field of power transmission and distribution, the distribution network is large in quantity and wide in range, the fault rate caused by low insulation level is high, and especially when a low-current single-phase earth fault occurs, the fault is very difficult to find due to the fact that a low-current fault signal is weak. Therefore, it is a very important problem to establish an insulation state evaluation system of the distribution line and evaluate the insulation state of the distribution line, so as to eliminate potential risks in time.
At present, an insulation state monitoring method utilizing transient signals is characterized in that transient grounding information of a low-current line selection device in a transformer substation is collected, only one insulation weak point exists in a current line is set, then, the insulation degradation degree of the insulation weak point is evaluated according to the transient grounding information, and the insulation degradation degree of the insulation weak point is used as the insulation state of the whole line.
However, in the existing insulation state evaluation method for the distribution line, because fault location information is lacked, the insulation state of the whole line is judged only according to the fault information at the bus of the substation, and the influence of transient ground faults, short-circuit faults and other reasons outside the current section on insulation weak points in the current section and the weight among various influence factors are not considered, the insulation state evaluation result of the distribution line is not accurate enough, and the reliability of the evaluation result is not high enough.
Disclosure of Invention
The application provides a distribution line insulation state evaluation method, which aims to solve the problems that in the prior art, the insulation state evaluation result of a distribution line is not accurate enough, and the reliability of the evaluation result is not high enough.
In order to solve the technical problem, the embodiment of the application discloses the following technical scheme:
a distribution line insulation state evaluation method, the method comprising:
establishing a distribution line insulation state evaluation model according to the fault information of the inside, outside and not-positioned areas and the operation condition of the distribution line;
when an insulation fault occurs, determining the value of the distribution line insulation state evaluation index according to the recording data of each monitoring point;
and according to the value of the distribution line insulation state evaluation index, evaluating the insulation state of each section of the distribution line by using a distribution line insulation state evaluation model.
Optionally, the establishing a distribution line insulation state evaluation model according to the in-zone, out-zone, and unset fault information and the distribution line operating condition includes:
selecting an insulation state evaluation index of the distribution line according to the fault information of the inside, outside and not-positioned areas and the operation condition of the distribution line;
evaluating the weight of the distribution line insulation state evaluation index by using an analytic hierarchy process;
and establishing a distribution line insulation state evaluation model according to the distribution line insulation state evaluation indexes and the weights thereof.
Optionally, the distribution line insulation state evaluation index includes: the method comprises the following steps of (1) evaluating indexes of intra-area fault information, evaluation indexes of extra-area fault information, evaluation indexes of unset fault information and evaluation indexes of line running states;
the intra-area fault information evaluation index includes: this instantaneous earth fault zero sequence voltage effective value U0kDuration time TD of the current transient earth faultkThe time interval T of the last earth fault in the current instantaneous earth fault distance zonekAnd counting the accumulated number N of instantaneous earth faults in the area in timek；
The evaluation indexes of the out-of-area fault information comprise: accumulated duration TD of external grounding fault in statistical timeGCounting the accumulated overvoltage times N of the external earth faults in timeOVGAnd counting the accumulated times N of the short-circuit faults at the downstream of the section in the timeSG；
The evaluation index of the non-positioned fault information comprises the following steps: counting the number N of times of undetermined instantaneous earth fault accumulation within timenp；
The line running state evaluation index comprises: time T for laying or erecting lineks。
Optionally, when the insulation fault occurs, determining a value of an insulation state evaluation index of the distribution line according to the recording data of each monitoring point, including:
when an insulation fault occurs, acquiring wave recording data uploaded by each monitoring point through a master station;
judging whether the wave recording data is fault data or not;
if yes, analyzing the fault data to determine a fault type and a fault location, wherein the fault type comprises: transient ground faults, permanent ground faults, and short circuit faults;
and obtaining the value of the distribution line insulation state evaluation index of each section according to the fault type and the fault location.
Optionally, the method for determining whether the recording data is fault data includes:
when any phase current energy or zero sequence current energy is larger than a threshold value W, judging the wave recording data as fault data;
otherwise, judging the wave recording data as the flexible data.
Optionally, the method for obtaining a value of an evaluation index of an insulation state of a distribution line in each section according to a fault type and a fault location includes:
when the fault type is an instantaneous ground fault, if the fault location is in the area, obtaining the values of the in-area fault information evaluation index and the line running state evaluation index, if the fault location is outside the area, obtaining the values of the out-area fault information evaluation index and the line running state evaluation index, and if the fault cannot be positioned or the positioning is unsuccessful, obtaining the values of the non-positioned fault information evaluation index and the line running state evaluation index;
when the fault type is a permanent earth fault, if the fault location is in the area, setting the values of the in-area fault information evaluation index and the out-area fault information evaluation index to zero, and if the fault location is out of the area, acquiring the values of the out-area fault information evaluation index and the line running state evaluation index;
and when the fault type is a short-circuit fault, if the fault location is in the area, setting the values of the in-area fault information evaluation index and the out-area fault information evaluation index to zero, and if the fault location is out of the area, acquiring the values of the out-area fault information evaluation index and the line running state evaluation index.
Optionally, the method for evaluating the insulation state of each section of the distribution line by using the distribution line insulation state evaluation model according to the value of the distribution line insulation state evaluation index includes:
calculating the insulation degradation degree of each section of the distribution line by using a distribution line insulation state evaluation model according to the value of the distribution line insulation state evaluation index;
obtaining the insulation state evaluation result of each section of the distribution line according to the insulation degradation degree of each section of the distribution line, wherein the evaluation result is divided into the following parts according to the severity degree in sequence: a severe state, an abnormal state, an attentive state, and a normal state.
Alternatively, the method for obtaining the insulation state evaluation result of each section of the distribution line according to the insulation deterioration degree of each section of the distribution line comprises the following steps:
when the insulation deterioration degree is [0,0.2], the evaluation result of the distribution line insulation state is a normal state;
when the degree of insulation deterioration is (0.2, 0.5), the evaluation result of the insulation state of the distribution line is an attentive state;
when the degree of insulation deterioration is (0.5, 0.8), the evaluation result of the distribution line insulation state is an abnormal state;
when the degree of insulation deterioration is (0.8, 1), the evaluation result of the insulation state of the distribution line is a serious state.
The technical scheme provided by the embodiment of the application can have the following beneficial effects:
the application provides a distribution line insulation state evaluation method, which comprises the steps of firstly, establishing a distribution line insulation state evaluation model according to in-area, out-area and unset fault information and distribution line operation conditions; secondly, when an insulation fault occurs, determining the value of the insulation state evaluation index of the distribution line according to the recording data of each monitoring point; and finally, according to the value of the distribution line insulation state evaluation index, evaluating the insulation state of each section of the distribution line by using a distribution line insulation state evaluation model. The distribution line insulation state evaluation model established by the method is based on the in-region, out-region, unset fault information and the distribution line running condition, therefore, the influence of factors such as the in-region, out-region and distribution line running condition on the insulation degradation degree of the insulation weak point in the region can be comprehensively considered, the evaluation region is more refined through subsection evaluation, and the insulation state of the distribution line can be evaluated more accurately. In addition, the weight of each evaluation index is determined by using an analytic hierarchy process, and the accuracy and reliability of the distribution line insulation state evaluation can be further improved.
According to the method and the device, the evaluation results including the serious state, the abnormal state, the attention state and the normal state are obtained after the distribution line insulation state is evaluated, the evaluation results can be refined, and different evaluation results correspond to different insulation degradation degrees. The method for classifying the evaluation results according to the severity of insulation degradation facilitates users to know the insulation state of the power distribution network at the current operation stage in time and give alarm signals in time when the insulation state is reduced to a certain degree, so that the users can take measures in advance to eliminate hidden troubles of faults, and further avoid the occurrence of permanent faults and faults such as sudden power failure and the like caused by the permanent faults. On the other hand, through the insulating state evaluation result that this application obtained, can in time learn distribution lines's insulating state to for circuit condition overhauls provide the basis, and then improve distribution lines's reliability. In addition, the severity of the low-current ground fault is influenced by the line insulation state, and the evaluation result of the distribution line insulation state is an important parameter for judging whether the low-current ground fault needs to be tripped or not, so that the fault range is prevented from being expanded, and therefore the method and the device can provide a basis for self-adaptive tripping protection of the low-current ground fault.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application.
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of a distribution line insulation state evaluation method according to an embodiment of the present application.
Detailed Description
In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, 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 application.
For a better understanding of the present application, embodiments of the present application are explained in detail below with reference to the accompanying drawings.
Referring to fig. 1, fig. 1 is a schematic flow chart of a distribution line insulation state evaluation method according to an embodiment of the present application. As shown in fig. 1, the method for evaluating the insulation state of the distribution line in this embodiment mainly includes the following steps:
s1: and establishing a distribution line insulation state evaluation model according to the fault information of the inside, outside and not-positioned areas and the operation condition of the distribution line.
Specifically, step S1 includes the steps of:
s11: and selecting an insulation state evaluation index of the distribution line according to the fault information of the inside, outside and un-positioned areas and the operation condition of the distribution line.
Distribution lines insulation state evaluation index in this embodiment mainly includes: the intra-area fault information evaluation index, the extra-area fault information evaluation index, the unset fault information evaluation index, and the line operating state evaluation index are respectively represented by U1, U2, U3, and U4.
The intra-area fault information evaluation index U1 includes: this instantaneous earth fault zero sequence voltage effective value U0kDuration time TD of the current transient earth faultkThe time interval T of the last earth fault in the current instantaneous earth fault distance zonekAnd counting the accumulated number N of instantaneous earth faults in the area in timekThe value of each index is u11、u12、u13And u14To indicate that: u shape1＝{u11,u12,u13,u14}. Of these in-zone failure information evaluation indexes, U0kCan reflect the size of the fault point to the ground resistance to a certain extent, U0kThe larger the insulation deterioration, the smaller the ground impedance indicating a fault point in the section; TDkThe longer the arc is, the longer the arc burning time of the fault point in the section is, the larger the insulation damage degree caused by the arc is, and the larger the reduction degree of the line insulation level is; t iskThe smaller the size, the frequency of the insulation ground fault in the section tends to rise, and the speed of insulation degradation is accelerated; n is a radical ofkThe larger the number of times of occurrence of insulation failure in the section in a short time, the more the insulation deterioration progresses toward permanent breakdown in a short time. When the insulation fault is evaluated in the area, the information of the insulation fault in the area can be more comprehensively acquired by selecting the zero sequence voltage effective value of the instantaneous ground fault, the duration of the instantaneous ground fault, the time interval of the instantaneous ground fault from the last ground fault in the area and the accumulated number of the instantaneous ground faults in the area in the statistical time, so that the accuracy of the insulation state grade evaluation is improved.
The evaluation index U2 of the out-of-range fault information includes: accumulated duration TD of external grounding fault in statistical timeGCounting the accumulated overvoltage times N of the external earth faults in timeOVGAnd counting the accumulated times N of the short-circuit faults at the downstream of the section in the timeSGThe value of each index is u21、u22And u23To indicate that: u shape2＝{u21,u22,u23}. Among these out-of-range fault information evaluation indexes, TDGThe greater the degree of insulation indicating a weak point of insulation in a zone, subject to an instantaneous earth fault outside the zoneThe greater the impact; n is a radical ofOVGThe larger the insulation, the more the overvoltage affects the degree of insulation indicating a weak point of insulation in the zone; n is a radical ofSGThe greater the degree of insulation indicating a weak point of insulation within a zone, the greater the impact of a short circuit fault. By counting the accumulated duration of the external grounding faults in the time, the accumulated overvoltage times of the external grounding faults in the time and the accumulated times of the downstream short-circuit faults of the sections in the time, the influence of the external fault information on the insulation degree of the insulating weak points in the area can be comprehensively collected, and therefore the accuracy and the reliability of the insulation state grade evaluation are improved.
The non-localized fault information evaluation index U3 includes: counting the number N of times of undetermined instantaneous earth fault accumulation in timenpThe value of the index is u31To indicate that: u shape3＝{u31}. In this embodiment, the recorded wave data is acquired by a fault indicator, NnpThe larger the insulation degradation, the greater the insulation degradation indicating the point of insulation weakness in the adjacent section downstream of the fault indicator to which the recorded data corresponds.
The line operating state evaluation index U4 includes: time T for laying or erecting lineksThe value of the index is u41To indicate that: u shape4＝{u41}。
Typically, the failure rate of a distribution line is plotted against time as a "bathtub", i.e.: at the initial stage of the distribution line, due to the quality problems of line accessory products and lines or the problems of erection, laying and installation, the lines are easy to have operation faults; the line body and the accessories operate stably in the middle operating period; the conditions of line insulation, line electrical aging, line thermal aging and the like are aggravated in the later operation period, so that the line fault rate is obviously increased. The method for evaluating the insulation state of the distribution line in the embodiment is suitable for the distribution line which passes the initial operation stage and meets TksThe greater the degree of insulation deterioration, and therefore, the degree of insulation deterioration of the distribution line can be effectively reflected by the time the line has been laid or erected.
After the distribution line insulation state evaluation index is determined, step S12 is executed: and evaluating the weight of the distribution line insulation state evaluation index by using an analytic hierarchy process.
In this embodiment, an analytic hierarchy process is used, and the weight for determining the evaluation index of the insulation state of the distribution line is as follows:
| index (I) | Weight of | Index (I) | Weight of | Index (I) | Weight of |
| U1 | 0.62 | u11 | 0.26 | u21 | 0.12 |
| U2 | 0.23 | u12 | 0.45 | u22 | 0.65 |
| U3 | 0.11 | u13 | 0.09 | u23 | 0.23 |
| U4 | 0.04 | u14 | 0.20 |
TABLE 1 distribution line insulation status each index weight
It should be noted that, according to the characteristics of different areas or different distribution lines, the weight of the insulation state evaluation index of the distribution line in the present application has different values, and the weight of the insulation state evaluation index of the distribution line provided in this embodiment is only an optimal way.
After the distribution line insulation state evaluation index and the weight thereof are determined, step S13 is executed: and establishing a distribution line insulation state evaluation model according to the distribution line insulation state evaluation indexes and the weights thereof.
According to the distribution line insulation state evaluation index and the weight thereof, the distribution line insulation state evaluation model is as follows: u is 0.62U1+0.23U2+0.11U3+0.04U4And U is1＝0.26u11+0.45u12+0.09u13+0.20u14，U2＝0.12u21+0.65u22+0.23u23Therefore, the distribution line insulation state evaluation model is as follows:
U＝0.1621u11+0.279u12+0.0558u13+0.124u14+0.0276u21+0.1495u22+0.0529u23+0.11u31+0.04u41。
since the distribution line insulation state evaluation indexes of different areas or different distribution lines have different weights, the distribution line insulation state evaluation models obtained according to the distribution line insulation state evaluation indexes and the weights thereof are different, and the distribution line insulation state evaluation model provided by the embodiment is only a preferable mode.
S2: and when the insulation fault occurs, determining the value of the distribution line insulation state evaluation index according to the recording data of each monitoring point.
Specifically, step S2 includes the following process:
s21: and when the insulation fault occurs, the main station acquires the wave recording data uploaded by each monitoring point.
S22: and judging whether the wave recording data is fault data.
Specifically, the method for judging whether the recording data is fault data includes:
s221: and when the energy of any phase current or the energy of the zero sequence current is greater than a threshold value W, judging the wave recording data as fault data.
Namely: when the current energy of a human phase is greater than a threshold value W, the wave recording data is judged to be fault data, and when the current energy of the zero sequence is greater than the threshold value W, the wave recording data is also judged to be fault data.
Otherwise, step S222 is executed: and when the energy of any phase current and the energy of the zero sequence current are less than or equal to the threshold value W, judging the wave recording data as the disturbance data.
Namely: and when the energy of any phase current is less than or equal to the threshold value W and the energy of the zero sequence current is less than or equal to the threshold value W, judging the wave recording data as the disturbance data.
In step S221 and step S222, the current energy is calculated by the following formula:
in the calculation formula of the current energy, i0And (T) represents zero sequence current in the recording data, wherein T is a period, and the period T in the embodiment is 0.02 s. As a preferred embodiment of this embodiment, W may take 1A2·s。
According to step S22, if the recording data is failure data, execute step S23: and analyzing the fault data to determine the fault type and the fault location. Wherein the fault types include: transient ground faults, permanent ground faults, and short circuit faults. And if the wave recording data are disturbance data, returning to the step S21, and continuously acquiring the wave recording data uploaded by each monitoring point through the main station.
After the failure type and the failure location are determined, step S24 is performed: and obtaining the value of the distribution line insulation state evaluation index of each section according to the fault type and the fault location.
Specifically, step S24 includes the following processes:
s241: when the fault type is instantaneous ground fault, obtaining the value of the distribution line insulation state evaluation index of each section according to the fault location:
if the fault location is in the area, obtaining the values of the evaluation index of the fault information in the area and the evaluation index of the line running state; if the fault location is outside the area, acquiring the values of an outside fault information evaluation index and a line running state evaluation index; and if the fault cannot be positioned or the positioning is unsuccessful, obtaining the values of the non-positioned fault information evaluation index and the line running state evaluation index.
S242: when the fault type is a permanent earth fault, obtaining the value of the distribution line insulation state evaluation index of each section according to the fault location:
and if the fault location is in the area, setting the values of the in-area fault information evaluation index and the out-area fault information evaluation index to zero. When the fault type is a permanent earth fault and the fault location is within the zone, it is determined that the point of weakness of the insulation is broken down, at which point the index information within and outside the zone is reset.
And if the fault location is outside the area, acquiring the values of the evaluation indexes of the outside fault information and the evaluation indexes of the line running state.
Namely: the fault is located in the area, and the fault information u in the area is updated11、u12、u13、u14And the line running state index value u31(ii) a The fault is located outside the zone and,updating out-of-area fault information u21、u22And the line running state index value u31(ii) a Failure in positioning or failure in positioning, updating the un-positioned failure information u31And line operating condition index u31。
In addition, because the signal intensity of the permanent ground fault is higher, the device can be positioned when working normally, and even if the positioning is unsuccessful, manual reporting can be carried out after manual inspection and positioning. Therefore, the method in the application is not adopted to obtain the value of the distribution line insulation state evaluation index for the permanent ground fault.
S243: when the fault type is a short-circuit fault, obtaining the value of the distribution line insulation state evaluation index of each section according to the fault location:
and if the fault location is in the area, setting the values of the in-area fault information evaluation index and the out-area fault information evaluation index to zero. And when the fault type is a short-circuit fault and the fault location is in the area, judging that the insulation weak point breaks down, and resetting index information in the area and outside the area.
And if the fault location is outside the area, acquiring the values of the evaluation indexes of the outside fault information and the evaluation indexes of the line running state.
S3: and according to the value of the distribution line insulation state evaluation index, evaluating the insulation state of each section of the distribution line by using a distribution line insulation state evaluation model.
Specifically, step S3 includes the following processes:
s31: and calculating the insulation degradation degree of each section of the distribution line by using the distribution line insulation state evaluation model according to the value of the distribution line insulation state evaluation index.
According to the value of the obtained distribution line insulation state evaluation index, a model U is 0.1621U11+0.279u12+0.0558u13+0.124u14+0.0276u21+0.1495u22+0.0529u23+0.11u31+0.04u41And calculating the insulation degradation degree of each section of the distribution line.
S32: and obtaining the insulation state evaluation result of each section of the distribution line according to the insulation degradation degree of each section of the distribution line. Wherein, the evaluation results are divided into the following according to the severity degree in turn: a severe state, an abnormal state, an attentive state, and a normal state.
Specifically, when the degree of insulation deterioration is [0,0.2], the evaluation result of the insulation state of the distribution line is a normal state; the evaluation result of the insulation state of the distribution line is an attentive state when the degree of insulation degradation is (0.2, 0.5), an abnormal state when the degree of insulation degradation is (0.5, 0.8), and a severe state when the degree of insulation degradation is (0.8, 1).
To sum up, in this embodiment, the influence of factors such as the operating conditions of the in-zone, the out-zone and the distribution lines on the insulation degradation degree of the insulation weak point in the zone is integrated, the insulation state of the distribution lines is evaluated by the subsections, the weights of the evaluation indexes are determined by using the analytic hierarchy process, and the insulation state of the distribution lines can be evaluated more accurately. Compared with the currently common insulation online monitoring method for measuring the partial discharge amount, the dielectric loss angle of the insulation layer and the like, the method provided by the application utilizes the instantaneous fault information and the historical fault data to evaluate the insulation state, not only can reduce the planned power failure time, but also can reduce the damage of a high-voltage preventive test to cables and equipment. Compared with a traditional insulation monitoring method only using instantaneous grounding information, the method provided by the application comprehensively considers the influence of grounding faults and short-circuit faults on insulation weak links, combines a section positioning result, and is more refined in evaluation area and higher in result reliability.
The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (5)
1. A distribution line insulation state evaluation method is characterized by comprising the following steps:
establishing a distribution line insulation state evaluation model according to the fault information of the inside, outside and not-positioned areas and the operation condition of the distribution line;
when an insulation fault occurs, determining the value of the distribution line insulation state evaluation index according to the recording data of each monitoring point;
according to the value of the distribution line insulation state evaluation index, the insulation state of each section of the distribution line is evaluated by using a distribution line insulation state evaluation model; the method comprises the following steps of establishing a distribution line insulation state evaluation model according to the in-area, out-of-area and unset fault information and the distribution line operation condition, wherein the method comprises the following steps:
selecting an insulation state evaluation index of the distribution line according to the fault information of the inside, outside and not-positioned areas and the operation condition of the distribution line;
evaluating the weight of the distribution line insulation state evaluation index by using an analytic hierarchy process;
establishing a distribution line insulation state evaluation model according to the distribution line insulation state evaluation indexes and the weights thereof;
when an insulation fault occurs, the value of the distribution line insulation state evaluation index is determined according to the recording data of each monitoring point, and the method comprises the following steps:
when an insulation fault occurs, acquiring wave recording data uploaded by each monitoring point through a master station;
judging whether the wave recording data is fault data or not;
if yes, analyzing the fault data to determine a fault type and a fault location, wherein the fault type comprises: transient ground faults, permanent ground faults, and short circuit faults;
obtaining values of distribution line insulation state evaluation indexes of each section according to the fault type and the fault location;
according to the value of the distribution line insulation state evaluation index, the method for evaluating the insulation state of each section of the distribution line by using a distribution line insulation state evaluation model comprises the following steps:
calculating the insulation degradation degree of each section of the distribution line by using a distribution line insulation state evaluation model according to the value of the distribution line insulation state evaluation index;
obtaining the insulation state evaluation result of each section of the distribution line according to the insulation degradation degree of each section of the distribution line, wherein the evaluation result is divided into the following parts according to the severity degree in sequence: a severe state, an abnormal state, an attentive state, and a normal state.
2. The distribution line insulation state evaluation method according to claim 1, wherein the distribution line insulation state evaluation index includes: the method comprises the following steps of (1) evaluating indexes of intra-area fault information, evaluation indexes of extra-area fault information, evaluation indexes of unset fault information and evaluation indexes of line running states;
the intra-area fault information evaluation index includes: this instantaneous earth fault zero sequence voltage effective value U0kDuration time TD of the current transient earth faultkThe time interval T of the last earth fault in the current instantaneous earth fault distance zonekAnd counting the accumulated number N of instantaneous earth faults in the area in timek；
The evaluation indexes of the out-of-area fault information comprise: accumulated duration TD of external grounding fault in statistical timeGCounting the accumulated overvoltage times N of the external earth faults in timeOVGAnd counting the accumulated times N of the short-circuit faults at the downstream of the section in the timeSG；
The evaluation index of the non-positioned fault information comprises the following steps: counting the number N of times of undetermined instantaneous earth fault accumulation within timenp；
The line running state evaluation index comprises: time T for laying or erecting lineks。
3. The distribution line insulation state evaluation method according to claim 1, wherein the method for judging whether the recording data is fault data comprises the following steps:
when any phase current energy or zero sequence current energy is larger than a threshold value W, judging the wave recording data as fault data;
otherwise, judging the wave recording data as the flexible data.
4. The distribution line insulation state evaluation method according to claim 1, wherein the method for obtaining the value of the distribution line insulation state evaluation index of each section according to the fault type and the fault location comprises:
when the fault type is an instantaneous ground fault, if the fault location is in the area, obtaining the values of the in-area fault information evaluation index and the line running state evaluation index, if the fault location is outside the area, obtaining the values of the out-area fault information evaluation index and the line running state evaluation index, and if the fault cannot be positioned or the positioning is unsuccessful, obtaining the values of the non-positioned fault information evaluation index and the line running state evaluation index;
when the fault type is a permanent earth fault, if the fault location is in the area, setting the values of the in-area fault information evaluation index and the out-area fault information evaluation index to zero, and if the fault location is out of the area, acquiring the values of the out-area fault information evaluation index and the line running state evaluation index;
and when the fault type is a short-circuit fault, if the fault location is in the area, setting the values of the in-area fault information evaluation index and the out-area fault information evaluation index to zero, and if the fault location is out of the area, acquiring the values of the out-area fault information evaluation index and the line running state evaluation index.
5. The method of claim 1, wherein the method of obtaining the insulation state evaluation results of the sections of the distribution line based on the degree of insulation degradation of the sections of the distribution line comprises:
when the insulation deterioration degree is [0,0.2], the evaluation result of the distribution line insulation state is a normal state;
when the degree of insulation deterioration is (0.2, 0.5), the evaluation result of the insulation state of the distribution line is an attentive state;
when the degree of insulation deterioration is (0.5, 0.8), the evaluation result of the distribution line insulation state is an abnormal state;
when the degree of insulation deterioration is (0.8, 1), the evaluation result of the insulation state of the distribution line is a serious state.
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