CN109799426B - Line instantaneous fault positioning method - Google Patents
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Abstract
The invention belongs to the technical field of power distribution network line protection, and particularly relates to a line instantaneous fault positioning method. According to the invention, instantaneous high-frequency signals generated by different types of faults are subjected to difference processing, so that each fault type has a uniform comparison domain comparison factor, and the fault judgment and fault positioning can be carried out more simply and efficiently. Based on the method, the invention effectively judges the position of the fault point by utilizing the energy parameter when the high-frequency transient signal occurs, does not need to carry out multi-point measurement in the monitoring process, has less measurement parameters and simple realization method, can effectively judge the position information of the fault occurrence by utilizing various existing detection devices, can realize simple and efficient automatic fault positioning and judgment by combining various positioning analysis methods, and has the characteristics of low cost and high reliability.
Description
Technical Field
The invention belongs to the technical field of power distribution network line protection, and particularly relates to a line instantaneous fault positioning method.
Background
When a power distribution fault occurs on a circuit, high-frequency transient signals can be generated on the circuit, the transient signals are transmitted along the circuit with a power transmission network and are transmitted among the circuits, generally, when the transient signals are transmitted to buses, the transient signals can be shielded and reduced through a capacitor assembly at the end part of each bus, so that the intensity of the transient signals is rapidly weakened, and therefore when detection values of the buses on two sides approach to a fault node along a power transmission line, the intensity change of the transient signals is obvious, and based on the phenomenon, a fault positioning and judging method based on the vertical detection comparison of the transient signal buses is developed.
Although the principle of the method is simple and convenient to implement, the method is low in precision and cannot accurately acquire the position information of the fault point, and particularly when other electric equipment or electric equipment is contained in a line, the method is possibly misjudged due to the interference of a load signal on an instantaneous fault signal, so that the fault judgment and positioning effects on the complex power distribution network are poor.
Disclosure of Invention
The invention aims to provide a line instantaneous fault positioning method which can enable each fault category to have a uniform comparison domain comparison factor by carrying out difference processing on instantaneous high-frequency signals generated by faults of different categories so as to conveniently and simply and efficiently carry out fault judgment and fault positioning.
In order to achieve the purpose, the invention adopts the following technical scheme.
The line instantaneous fault positioning method specifically comprises the following steps:
1. for two branch lines L connected between the buses and connected with the same bus1、L2Respectively detecting instantaneous current I at the junction of branch line and bus1、I2And its corresponding high-frequency component I1h、I2h；
2. Calculating the high frequency component I1h、I2hCorresponding energy P1h、P2h(ii) a Wherein
3. For branch energy P1h、P2hCalculating an energy comparison factor thereof
Wherein gamma is a comparison factor, and the phase angle theta when the fault used in the process of calculating the energy corresponding to the high-frequency component occurs is calculatedf；
4. When P is present1h＞P2hAnd | P1h-P2h|＞100max{|P1h|、|P2hIf the fault point is located on branch line L1When P is1h＜P2hAnd | P1h-P2hIf L is large, the fault point is located on the branch line L2The above step (1);
when P is present1h＞P2hAnd | P1h-P2h|＜0.1max{|P1h|、|P2hIf the fault point is located on the branch line L of the bus1On one side and not on branch line L1The above step (1);
when P is present1h、P2hAlternating in magnitude and | P1h-P2h|＜0.1max{|P1h|、|P2hIf the fault point is located on the bus or other straight line connected with the bus.
Based on the method, the invention effectively judges the position of the fault point by utilizing the energy parameter when the high-frequency transient signal occurs, does not need to carry out multi-point measurement in the monitoring process, has less measurement parameters and simple realization method, can effectively judge the position information of the fault occurrence by utilizing various existing detection devices, can realize simple and efficient automatic fault positioning and judgment by combining various positioning analysis methods, and has the characteristics of low cost and high reliability.
In the line instantaneous fault locating method, the phase angle theta when the fault occurs is determinedfComprises the following steps:
1. dividing phase voltage and phase current into V-shaped light velocity based on module component principle0The propagating mode component A, the mode component B and the velocity V at a speed lower than the speed of light1＝V0X, (0 < x < 1) the propagating modal component C;
2. measuring the time T when the modulus component A and C reach the detection point for the first timeA、TCTime of occurrence of failure To(ii) a The time T corresponding to the time when the voltage changes from negative to positive zero in the fault occurrence periodk；
3. Calculating the phase angle at the time of the fault
Wherein f isuIs the line current phase change frequency.
Based on the steps, the acquisition and analysis processes of the parameters can be simplified, and meanwhile, the method is combined with the existing detection scheme, so that the efficiency of analysis and processing is improved, and a technical basis is provided for the automatic, efficient and convenient realization.
A further addition to the above line instantaneous fault location method also includes, on either side, the distance L from the fault point to the detection point being (T ═ T)c-To)·V1. Based on the above, the specific position of the fault point can be further determined, and the effect of fault location is improved.
Comparing factors for the line instantaneous fault positioning method
Wherein a, b, c and d are constant coefficientsThe experiment is obtained by calculation, and for a circuit of 50-500 kV, a is 0.035, b is-0.022, c is 0.826 and d is-0.005. Based on actual test, the distance error in detection by adopting the parameters is less than 100m, and the fault point can be effectively determined by combining the modes of field inspection and the like, so that the actual requirement of fault positioning can be met, and redundant parameter calculation and analysis are not required.
Drawings
Fig. 1 is a schematic diagram of a fault analysis principle of a common power transmission line.
1 2Description of the drawings: l, LFor two branch lines
Detailed Description
The invention is described in detail below with reference to specific embodiments.
When a power distribution network fault occurs, instantaneous high-frequency signals can be generated along with the fault occurrence, the instantaneous high-frequency fault signals can generate instantaneous signals with completely different characteristics under different phase points and power grid data, and the instantaneous high-frequency signals are different for different types of faults.
The invention is used as the energy factor of the instantaneous high-frequency fault signal as the comparison factor, and eliminates the influence of the phase and the power grid data on the instantaneous signal when the fault is generated based on the judgment of the energy factor;
the line instantaneous fault positioning method specifically comprises the following steps:
1. for two branch lines L connected between the buses and connected with the same bus1、L2Respectively detecting instantaneous current I at the junction of branch line and bus1、I2Corresponding high frequency component I1h、I2h；
2. Calculating the high frequency component I1h、I2hCorresponding energy P1h、P2h(ii) a Wherein
As shown in figure 1, when the analysis is carried out by taking a conventional power transmission line as a reference, the fault phase angle at the moment of the fault of the line can influence the branch line energy P1h、P2hTherefore, the energy parameters are firstly reduced, and criterion analysis is carried out according to the reduced energy comparison factors. The method comprises the following steps:
3. for branch energy P1h、P2hCalculating an energy comparison factor thereof
Wherein gamma is a comparison factor, and the phase angle theta when the fault used in the process of calculating the energy corresponding to the high-frequency component occurs is calculatedf；
In the line instantaneous fault locating method, the phase angle theta when the fault occurs is determinedfComprises the following steps:
dividing phase voltage and phase current into V-shaped light velocity based on module component principle0The propagating mode component A, the mode component B and the velocity V at a speed lower than the speed of light1＝V0X, (0 < x < 1) the propagating modal component C; measuring the time T when the modulus component A and C reach the detection point for the first timeA、TCTime of occurrence of failure To(ii) a The time T corresponding to the time when the voltage changes from negative to positive zero in the fault occurrence periodk(ii) a Calculating the phase angle at the time of the fault
fuIs the line current phase change frequency;
for the existing transmission line with known structure and transmission parameters, the comparison factor gamma is a statistical parameter, the numerical precision of the comparison factor corresponds to the actual positioning precision, and
the constant coefficients a, b, c and d are obtained by experimental reduction, and for a circuit of 50-500 kV, on the premise of meeting the positioning accuracy, the actual calculation requirements are considered, and a is 0.035, b is-0.022, c is 0.826 and d is-0.005.
Analyzing the line as branch line L1When the fault occurs, the total energy value of the high-frequency component close to the fault side is far larger than that of the high-frequency component far away from the fault side, namely P, due to the bypass effect of the bus on the ground distributed equivalent capacitor1h＞P2hAnd the absolute value of the difference is large, when the fault occurs in the branch line L1One side but not at branch line L1Upper, then P1h＞P2hAnd the absolute value of the difference is small; the energy values when the faults of different node positions in the power transmission line occur are counted to obtain that:
when the power line branch line L1Internal failures, resulting in the energy data table shown in table 1:
TABLE 1 Branch line L1Energy at fault | P1h-P2h| detection data value
As can be seen from Table 1, in the branch line L1When the fault occurs, the fault characteristic quantity is far greater than 6 multiplied by 104；
When a transmission line bus fails, an energy data table as shown in table 2 is obtained:
TABLE 2 energy | P at bus Fault1h-P2h| detection data value
As can be seen from the above table, the failure characteristic quantity satisfies 1 × 104＜|P1h-P2h|＜3×104And by the principle, the data result of the fault characteristic quantity when other nodes have faults can be obtained in the same way.
4. When P is present1h＞P2hAnd | P1h-P2h|＞100max{|P1h|、|P2h|}，The point of failure is located on the branch line L1When P is1h＜P2hAnd | P1h-P2hIf L is large, the fault point is located on the branch line L2The above step (1);
when P is present1h＞P2hAnd | P1h-P2h|＜0.1max{|P1h|、|P2hIf the fault point is located on the branch line L of the bus1On one side and not on branch line L1The above step (1);
when P is present1h、P2hAlternating in magnitude and | P1h-P2h|＜0.1max{|P1h|、|P2hIf the fault point is located on the bus or other straight line connected with the bus.
Wherein f isuIn order to change the phase frequency of the line current, the line instantaneous fault location method further comprises the step of determining the distance L between a fault point and a detection point on any side (T)c-To)·V1。
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.
Claims (3)
1. A line instantaneous fault positioning method is characterized by comprising the following steps:
for two branch lines L connected between buses and connected with the same bus1、L2Respectively detecting instantaneous current I at the junction of branch line and bus1、I2And its corresponding high-frequency component I1h、I2h；
② calculating high-frequency component I1h、I2hCorresponding energy P1h、P2h(ii) a Wherein
③ branch energy P1h、P2hCalculating an energy comparison factor thereof
Wherein gamma is a comparison factor, and the phase angle when the fault used in the process of calculating the energy corresponding to the high-frequency component occurs is thetaf；
Wherein the phase angle theta at the occurrence of a fault is determinedfComprises the following steps:
dividing phase voltage and phase current into V-shaped light velocity based on module component principle0The propagating mode component A, the mode component B and the velocity V at a speed lower than the speed of light1＝V0X, (0 < x < 1) the propagating modal component C; measuring the time T when the modulus component A and C reach the detection point for the first timeA、TCTime of occurrence of failure To(ii) a The time T corresponding to the time when the voltage changes from negative to positive zero in the fault occurrence periodk(ii) a Calculating the phase angle at the time of the fault
fuIs the line current phase change frequency;
wherein
Wherein a is 0.035, b is-0.022, c is 0.826, d is-0.005;
when P1h＞P2hAnd | P1h-P2h|＞100max{|P1h|、|P2hIf the fault point is located on branch line L1When P is1h＜P2hAnd | P1h-P2h|＞100max{|P1h|、|P2hIf the fault point is located on branch line L2The above step (1);
when P is present1h＞P2hAnd | P1h-P2h|＜0.1max{|P1h|、|P2hIf the fault point is located on the branch line L of the bus1On one side and not on branch line L1The above step (1);
when P is present1h、P2hAlternating in magnitude and | P1h-P2h|＜0.1max{|P1h|、|P2hIf the fault point is located on the bus or other straight line connected with the bus.
2. A line instantaneous fault location method according to claim 1, characterized in that the phase angle θ when the fault occurs is determinedfComprises the following steps:
(1) dividing phase voltage and phase current into V-shaped light velocity based on module component principle0The propagating mode component A, the mode component B and the velocity V at a speed lower than the speed of light1＝V0X, (0 < x < 1) the propagating modal component C;
(2) measuring the time T when the modulus component A and C reach the detection point for the first timeA、TCTime of occurrence of failure To(ii) a The time T corresponding to the time when the voltage changes from negative to positive zero in the fault occurrence periodk；
(3) Calculating the phase angle at the time of the fault
Wherein f isuIs the line current phase change frequency.
3. A method as claimed in claim 1, wherein, at any side, the distance L (T) from the fault point to the detection point is equal to (T)c-To)·V1。
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