CN113466628A - Small current ground fault distance measurement method for power distribution network resonance grounding system - Google Patents
Small current ground fault distance measurement method for power distribution network resonance grounding system Download PDFInfo
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Abstract
A small current grounding fault distance measuring method for a power distribution network resonance grounding system. The technical field of power distribution network fault detection is related, and specifically relates to a power distribution network resonance grounding system low current grounding fault distance measuring method. The method comprises the following steps: s1: distributing a plurality of power distribution terminals on a power distribution network line, and acquiring real-time power frequency zero-sequence voltage information of a fault line and section information of a fault point when a small current ground fault occurs in a resonant grounding system; s2: dividing a fault line into a fault point upstream section, a fault point downstream main section and a fault point downstream branch section according to the section information of the fault point; the invention has unique research view and a new method for the positioning method of the small current grounding fault and also has important academic reference value.
Description
Technical Field
The invention relates to the technical field of power distribution network fault detection, in particular to a small current grounding fault distance measuring method for a power distribution network resonance grounding system.
Background
With the rapid development of economy and the continuous improvement of the living standard of people, the demand of the quality of electric energy is rapidly increased. Therefore, the safety and reliability of the operation of the power distribution network become important research targets, and the low-current ground fault plays an important role in factors affecting the healthy operation of the power distribution network. When the resonance grounding system has a low-current grounding fault, the fault current of the grounding point is small due to the compensation effect of the arc suppression coil. In the conventional power distribution network operation specifications, the live operation is allowed for 1-2 hours, but the zero sequence current which lasts for a long time is harmful to the power distribution network, and the mode of manually patrolling the line to find a fault point needs a long time. In recent years, power grid enterprises gradually modify relevant specifications aiming at rapidly isolating and removing faults. At present, the fault isolation method is mainly implemented by judging a section where a fault is located; the entire section is then isolated. The method and the device ensure the rapidity of fault removal and the safety of system operation, and simultaneously sacrifice the reliability of power supply. If the position of a fault point can be found quickly, the fault can be repaired within a time range with less harm, and power supply can be uninterrupted, so that the operation safety of the power distribution network can be ensured, and the reliability of power supply can also be ensured. The power distribution network fault location technology can judge the position of a fault point, and is a key for improving the fault point searching speed and improving the power supply reliability.
The existing power distribution network fault location technology can be divided into a fault section location technology and a fault distance measurement technology.
The fault section positioning technology is used for judging a section where a fault is located through related technical means so as to rapidly remove the fault. However, the specific fault point position in the technology needs to be searched by manual line patrol, the manual line patrol is a key factor influencing the further improvement of the fault searching and repairing speed, the labor intensity is high, the reliability is low, and the judgment period is long.
The fault location technology judges the distance of the fault point through related technical means to obtain the position of the relatively accurate fault point. Obviously, the fault location technology has more outstanding superiority in positioning accuracy, but the superiority of the technology is often in direct proportion to the development difficulty, so that the current fault section positioning technology is mature, and the fault location technology is in a development stage. Receive distribution network topological structure complicacy, circuit parameter inhomogeneous, factor influences such as operation mode variety, fault location technology development is comparatively difficult, and there is the problem that economic nature and range finding precision are difficult to compromise in current distribution network fault location technology: the method with high fault location precision usually needs to add new equipment, and has larger investment; the method with less investment is not high in distance measurement precision.
At present, the main fault location methods include a traveling wave method and an impedance method.
The traveling wave method is divided into a single-end method and a double-end method, both of which require a high-precision distance measuring device, wherein the double-end method has high requirements on the device, the traveling wave method measures the distance by using the transmission property of fault transient traveling waves, is not influenced by factors such as a system operation mode, transition resistance and the like, has high distance measuring precision, but has a complex distribution line structure and numerous branches, and is difficult to solve the problems of identification of fault wave heads and wave impedance change of a mixed line. Meanwhile, the distance of the power distribution network line is short, multiple sets of traveling wave detection equipment are needed, and the economic cost is high, so that the traveling wave method is difficult to be applied to the power distribution network.
The impedance method is also divided into a single-end method and a double-end method, the impedance method utilizes voltage and current information after a fault to calculate the impedance of a fault loop, and fault location is carried out according to the proportional relation between the line length and the impedance, the principle is simple and reliable, the stability is good, but the impedance method is easily influenced by factors such as fault transition resistance, incomplete line symmetry and the like, the error of a calculation result is large, and the effect is not ideal in practical application.
The power distribution terminal in the automatic system of the existing power distribution network can detect real-time fault data of a line and upload the data to the main station platform, if potential of the data can be fully mined, the data are applied to a fault location technology, the location accuracy is improved as much as possible, the fault location requirement can be met on the basis that new equipment is not added, the economical efficiency is guaranteed, and the application value is achieved.
Disclosure of Invention
The invention provides a power distribution network resonance grounding system small current grounding fault distance measuring method which aims at the problems and obtains voltage information of a corresponding position of a fault line through reasonably distributing power distribution terminal equipment of a power distribution network automation system, and judges the position of the fault point according to the distribution rule of power frequency zero sequence voltage of the fault line when the resonance grounding system has a small current grounding fault.
The technical scheme of the invention is as follows:
a small current grounding fault distance measuring method of a power distribution network resonance grounding system,
the method comprises the following steps:
s1: distributing a plurality of power distribution terminals on a power distribution network line, and acquiring real-time power frequency zero-sequence voltage information of a fault line and section information of a fault point when a small current ground fault occurs in a resonant grounding system;
s2: dividing a fault line into a fault point upstream section, a fault point downstream main section and a fault point downstream branch section according to the section information of the fault point;
s3: respectively fitting power frequency zero-sequence voltage information of the power distribution terminal into a power frequency zero-sequence voltage distribution curve of an upstream section of a fault point and a power frequency zero-sequence voltage distribution curve of a downstream trunk section of the fault point by using a curve fitting method, and solving a curve intersection point to determine the position of the fault point on a trunk line;
s4: if the distance between the fault position determined in the step S3 and the branch point does not exceed E, the flow proceeds to a step S5;
if the distance between the fault position determined in the step S3 and the branch point is larger than E, finishing ranging;
s5: and respectively fitting the power frequency zero-sequence voltage information of the power distribution terminal into a power frequency zero-sequence voltage distribution curve of an upstream section of the fault point and a power frequency zero-sequence voltage distribution curve of a downstream branch section of the fault point by using a curve fitting method, and solving a curve intersection point to determine the position of the fault point on the branch line.
In step S1, the layout method of the power distribution terminal includes:
main line layout: extending outwards by a bus, and arranging a power distribution terminal every time when the bus passes through a distance of at most P;
branch line layout: extending outwardly at a branch point, one distribution terminal is provided for each distance of up to Q.
In the trunk line layout, the distribution terminal is provided directly on the trunk line or on the branch line at a distance of at most Q from the branch point.
The processing of the distribution terminal on the branch line in step S3:
if a branched power distribution terminal is arranged between the bus and the fault point, the branched line is ignored;
if a branch power distribution terminal exists between the fault point and the load, the distance between the scoring fulcrum and the bus is m, and the distance between the branch power distribution terminal and the branching point is n, the branch power distribution terminal is planned to be positioned on a main section which is m + n away from the bus.
The fitting method of the power frequency zero sequence voltage distribution curve of the fault point upstream section, the power frequency zero sequence voltage distribution curve of the fault point downstream main section and the power frequency zero sequence voltage distribution curve of the fault point downstream branch section comprises the following steps:
taking the distance x from a fault point to a bus as an abscissa, and taking the power frequency zero sequence voltage amplitude U at the position of x0(x) Is a longitudinal directionAnd (3) establishing a distribution curve of power frequency zero sequence voltage by coordinates as follows:
U0(x)＝ax2+bx+c (I)
wherein a, b and c are respectively a quadratic coefficient, a primary coefficient and a constant.
When fitting the curve, each power distribution terminal is used as a detection point to provide the required power frequency zero sequence voltage information, wherein,
the number of detection points of the upstream section of the fault point is more than or equal to 2, and the number of detection points of the downstream main section of the fault point is more than or equal to 1;
if the section where the fault point is located is provided with branches, the number of detection points of the branch section at the downstream of the fault point is more than or equal to 1.
When the number of detection points is 1, let a be 0 and U0(x) Fitting as a constant function, i.e.
U0(x)＝c (2)。
When the number of detection points is 2, let a be 0, U0(x) Fitting as a linear function, i.e.
U0(x)＝bx+c (3)；
Let the detection point data be (x)1,U0(x1)),(x2,U0(x2) Substituting formula (3) to obtain
When the number of detection points is 3, U0(x) Fitting into a quadratic function, and setting the detection point data as (x)1,U0(x1))、(x2,U0(x2))、(x3,U0(x3) Substituting the formula (1),
order to
Then
When the number of detection points is more than 3, U0(x) Fitting into a quadratic function, and setting the detection point data as
(xi,U0(xi) I is 1,2,., n (n is not less than 4), and the mean square error formula of a, b and c is obtained according to the formula (1)
Using the minimum mean square error as the constraint condition, the solving formula of a, b and c is
According to the method for positioning the small-current ground fault of the resonance grounding system by using the power frequency zero sequence voltage distribution function, the power distribution terminals of the power distribution network automation system are reasonably distributed, so that when the system has the small-current ground fault, the position of the fault on a main line can be judged firstly, then the position of the fault on a branch line can be judged, and accurate fault position information can be finally obtained. The invention has important application value: on one hand, a power frequency zero sequence voltage information fitting curve in fault is utilized, and a fault positioning method which is simple in principle and effective is provided under the condition that fault information obtained by the existing fault detection device (power distribution terminal) is limited; on the other hand, the information potential of the existing power distribution terminal is fully exploited, the high cost for purchasing new equipment is avoided, and the method has important economic benefits. In addition, the invention has unique and novel research view and important academic reference value for the small current grounding fault positioning method.
On the other hand, in the traveling wave method in the prior art, the transmission and reflection of the traveling wave can be influenced by the complex line structures of the power distribution network, such as joints, branches, mixed connection and the like, so that the measurement is greatly influenced by the line structures. In contrast, the power frequency zero sequence voltage distribution curve is based on a (simulated) straight line and is less influenced by the line structure, so that the power frequency zero sequence voltage distribution curve has higher positioning reliability. The invention can of course also be used in combination with existing fault location methods to meet the positioning requirements of higher accuracy.
Drawings
Figure 1 is a flow chart of the operation of the present invention,
figure 2 is a circuit diagram of the equivalent distribution parameter of the small current grounding fault of the resonant grounding system in the invention,
figure 3 is a schematic diagram of the distribution of zero sequence current of the fault line of the resonant grounded system in the invention,
figure 4 is a schematic diagram of the zero sequence voltage distribution of the fault line of the resonant grounded system in the invention,
figure 5 is a schematic diagram of a simulation model of a 10kV resonant grounded system,
figure 6 is a simulation model fault line topology,
figure 7 is a main line power frequency zero sequence voltage distribution diagram of a resonant grounding system fault,
fig. 8 is a distribution diagram of the branch line power frequency zero sequence voltage of the resonant grounded system fault.
Detailed Description
The invention is further described below with reference to fig. 1-8.
The invention discloses a small current ground fault location method of a power distribution network resonance grounding system, which is used for fault location of a fault line, wherein a power distribution terminal is arranged on the fault line and used for providing real-time power frequency zero sequence voltage information and identifying a fault section, and the position of the power distribution terminal is a detection point.
The theoretical basis of the invention is the distribution rule of power frequency zero sequence voltage when the small current ground fault occurs in the resonance grounding system, the distribution parameter model shown in figure 2 is adopted for analyzing the resonance grounding system, when the system normally operates, the ground capacitance current exists between each position of the circuit and the ground, and if the voltage loss does not exist in the circuit and the circuit parameters are uniform, the ground capacitance current of unit length is consistent, and is set as IC. In order to prevent the over-large ground current during fault from causing other harm, the resonance grounding system compensates the capacitance current of fault grounding by grounding a neutral point on a bus side through an arc suppression coil, so that the compensation is realizedThe residual current is small, and the compensation mode is usually 8% -10% of overcompensation. When a small current ground fault occurs in the system, the circuit, the ground distributed capacitor and the arc suppression coil form a loop through a ground point, and the ground capacitor current and the arc suppression coil ground current at each part of the circuit are superposed and then flow into the system through a fault point to form zero sequence current. With the fault line as the analysis object, it can be known from the above analysis that the zero sequence current from the fault point to the bus is formed by overlapping two components, component 1 is the capacitance current to ground in the upstream direction of the fault point, component 2 is the grounding current of the arc suppression coil, and the two components are opposite in direction in the vector coordinate system, so the overlapped result is a subtraction relation, and from the fault point to the bus component 1, the component 2 is gradually reduced, and the zero sequence current after the overlap is gradually increased as can be known from the analysis of fig. 2. The zero sequence current from the fault point to the end of the fault line is reduced uniformly and only includes the capacitive current to ground between the fault point and the end of the fault line. The zero sequence current distribution of the fault line is shown in fig. 3.
Under the action of zero sequence impedance and zero sequence current of the line, zero sequence voltage drop can be generated when the zero sequence current propagates along the line. Setting the total length of the fault line as l, the distance between the fault point and the bus as X, the unit impedance of the line as X, and the total earth capacitance current of the sound line as IC∑The grounding current of the arc suppression coil is ILpThe zero sequence voltages of the bus, the fault point and the tail end of the fault line are respectively U1、U0、U2. According to the zero sequence current distribution, the line impedance and the line length, the zero sequence voltage distribution of the fault line can be deduced. Wherein the zero sequence voltage drop from the bus to the fault point is:
the zero-sequence voltage drop from the end of the fault line to the fault point is:
the following conclusions can be drawn by the analytical formula:
(1) the zero sequence voltage of the fault line is in an ascending trend from the bus to the fault point: when the ratio of the capacitance-to-ground current from a fault point to a bus section in a fault line to the total capacitance-to-ground current of the system is higher, the capacitance-to-ground current approximately rises in a quadratic function manner; when the capacitance-to-ground current ratio of the section is low, the section rises approximately in a linear function.
(2) The zero sequence voltage of the fault line is in an ascending trend from a fault point to the tail end of the line: when the capacitance current to ground from a fault point to the tail end section of the line in the fault line is large, the capacitance current rises in a quadratic function; when the capacitance current to the ground of the section is small, the section shows an unobvious linear change and can be approximately regarded as constant. The zero sequence voltage distribution of the fault line is shown in fig. 4.
The distance measuring method comprises the following steps:
s1: distributing a plurality of power distribution terminals on a power distribution network line, and acquiring real-time power frequency zero-sequence voltage information of a fault line and section information of a fault point when a small current ground fault occurs in a resonant grounding system;
s2: dividing a fault line into a fault point upstream section, a fault point downstream main section and a fault point downstream branch section according to the section information of the fault point; the fault line is an outgoing line where a fault with the bus as a starting point is located, and the fault section is a section between distribution terminal equipment on two sides of the fault point. The power distribution network automation system can acquire real-time voltage and current information of a fault through power distribution terminal equipment after the fault occurs, and the method needs the power frequency zero sequence voltage amplitude of the small current ground fault of the fault line, so that only the zero sequence voltage information of the fault needs to be selected. And determining the starting time of the fault, and selecting the zero sequence voltage amplitude of each detection point under the steady-state power frequency condition after the fault occurs to serve as a data basis of the method. After a power distribution terminal detects that a fault occurs, zero sequence voltage information of 3-5 cycles before the fault of a fault line to 7-10 cycles after the fault is uploaded to a power distribution automation main station platform, and after the fault reaches a steady-state stage, power frequency zero sequence voltage amplitude information of each detection point is selected, but different methods can be adopted when the power frequency zero sequence voltage information is selected due to different actual conditions: if the zero sequence voltage of the fault line in the cycle after the fault reaches a steady state, the amplitude of the zero sequence voltage can be directly selected as the power frequency zero sequence voltage amplitude; if the fault in the cycle after the fault does not reach the steady state, the power frequency zero sequence voltage amplitude of the fault can be selected by adopting a filtering method.
S3: respectively fitting power frequency zero-sequence voltage information of the power distribution terminal into a power frequency zero-sequence voltage distribution curve of an upstream section of a fault point and a power frequency zero-sequence voltage distribution curve of a downstream trunk section of the fault point by using a curve fitting method, and solving a curve intersection point to determine the position of the fault point on a trunk line; the step is used for judging the position of a fault point on a trunk line and neglecting an upstream branch line; ignoring the downstream branch line, or planning the detection point of the downstream branch to be positioned on the downstream main line;
s4: if the distance between the determined fault position and the branch point does not exceed E, that is, the measured fault point is near the branch point, the fault point may be located on the branch line, and the process proceeds to step S5 to determine the position of the fault point on the branch line;
if the distance between the fault position determined by the step S3 and the branch point is larger than E, the measured fault point is indicated to be eliminated from being positioned on the branch line, and the distance measurement is finished; a person skilled in the art can set E within the range of 80-200 m according to the actual line condition;
s5: and respectively fitting the power frequency zero-sequence voltage information of the power distribution terminal into a power frequency zero-sequence voltage distribution curve of an upstream section of the fault point and a power frequency zero-sequence voltage distribution curve of a downstream branch section of the fault point by using a curve fitting method, and solving a curve intersection point to determine the position of the fault point on the branch line.
In step S1, the layout method of the power distribution terminal includes:
main line layout: extending outwards by a bus, and arranging a power distribution terminal every time when the bus passes through a distance of at most P; the person skilled in the art can set P to be within 4Km according to the actual line condition;
branch line layout: extending outward at a branch point, and arranging a power distribution terminal every time when a distance of at most Q is passed; those skilled in the art can set Q to be within 2.5Km according to the actual line situation.
In the trunk line layout, the distribution terminal is provided directly on the trunk line or on the branch line at a distance of at most Q from the branch point.
Processing of the distribution terminal on the branch line in step S3:
if a branched power distribution terminal is arranged between the bus and the fault point, the branched line is ignored;
if a branch power distribution terminal exists between the fault point and the load, the distance between the scoring fulcrum and the bus is m, and the distance between the branch power distribution terminal and the branching point is n, the branch power distribution terminal is planned to be positioned on a main section which is m + n away from the bus.
The fitting method of the power frequency zero sequence voltage distribution curve of the fault point upstream section, the power frequency zero sequence voltage distribution curve of the fault point downstream main section and the power frequency zero sequence voltage distribution curve of the fault point downstream branch section comprises the following steps:
taking the distance x from a fault point to a bus as an abscissa, and taking the power frequency zero sequence voltage amplitude U at the position of x0(x) For the ordinate, the distribution curve of the power frequency zero sequence voltage is established as follows:
U0(x)＝ax2+bx+c (I)
wherein a, b and c are respectively a quadratic coefficient, a primary coefficient and a constant.
When fitting the curve, each power distribution terminal is used as a detection point to provide the required power frequency zero sequence voltage information, wherein,
the number of detection points in the upstream section of the fault point is more than or equal to 2, if the number of the detection points is 1, only one constant function can be fitted according to the data of the detection points, the error of the distance measurement result obtained by calculation is extremely large, and the application of the distance measurement result is excluded from practical application; the number of detection points of a main section at the downstream of a fault point is more than or equal to 1;
if the section where the fault point is located is provided with branches, the number of detection points of the branch section at the downstream of the fault point is more than or equal to 1.
When the number of detection points is 1, let a be 0 and U0(x) Fitting as a constant function, i.e.
U0(x)＝c (2)。
When the number of detection points is 2, let a be 0, U0(x) Fitting as a linear function, i.e.
U0(x)＝bx+c (3)；
Let the detection point data be (x)1,U0(x1)),(x2,U0(x2) Substituting formula (3) to obtain
When the number of detection points is 3, U0(x) Fitting into a quadratic function, and setting the detection point data as (x)1,U0(x1))、(x2,U0(x2))、(x3,U0(x3) Substituting the formula (1),
order to
Then
When the number of detection points is more than 3, U0(x) Fitting into a quadratic function, and setting the detection point data as (x)i,U0(xi) I, · 1., 2n, (n, ≧ n), the mean square error formula of a, b, c is obtained according to formula (1) as
Using the minimum mean square error as the constraint condition, the solving formula of a, b and c is
The step can eliminate the interference of abnormal detection point data, so that the fitted power frequency zero sequence voltage distribution curve can fully show the trend characteristics of the fitted power frequency zero sequence voltage distribution curve, and the accurate judgment of the fault point is ensured.
Example (b):
the using steps of the method are described in detail in combination with a simulation model.
A10 kV single-end radial and neutral point arc suppression coil grounding system simulation model is established by using an MATLAB software tool, 5 outgoing lines are totally arranged on a bus side of the system and comprise 2 cables and 3 overhead lines, the lengths of the cables are respectively 4km and 5km, the lengths of the overhead lines are respectively 9km, 11km and 14km, 110kV of the bus side adopting a Y-delta connection method is changed into 10kV, and loads are respectively connected with three-phase balanced loads of 0.5MW +0.08MVar, as shown in figure 5.
Branch lines are respectively added at the positions of 2km, 6km and 10km from the 14km overhead line to the bus, the lengths of the branch lines are respectively 2.5km, 2.5km and 2.5km, and the branch lines are respectively connected with a three-phase balanced load of 0.3MW +0.06 MVar.
Taking the resonant grounding system as an example to perform fault location:
in 14km overhead lines, a single-phase earth fault is arranged at a branch line 1.5km away from a branch point at a distance of 6km from a bus, the fault phase is A phase, the fault initial phase angle is 90 degrees, and the fault earth resistance is 10 omega.
Layout of power distribution terminals: arranging distribution terminals (hereinafter referred to as detection points 1#, 2#, 3#, 4#, and 5 #) at positions of 0km, 4km, 8km, 12km, and 14km away from a bus of a main line of a fault line and 5 km; the tail end of each branch line is provided with a power distribution terminal (detection points b1#, b2#, and b3# are shortened from small to large according to the distance from the bus). The faulty line topology is shown in fig. 6.
TABLE 1 Power frequency zero sequence voltage amplitude of each detection point of fault line main line
TABLE 2 Power frequency zero sequence voltage amplitude of each detection point of fault line branch line
After the fault occurs, the zero sequence voltage reaches a stable state in 85ms, when the resonance grounding system has a small-current grounding fault, real-time power frequency zero sequence voltage information of a fault circuit is obtained by using terminal equipment of a power distribution network automation system, the stable power frequency zero sequence current amplitude of each detection point is obtained, and the data of each detection point is shown in tables 1 and 2.
The known fault point is located between detection points 2# and 3# of the main trunk line, and the fault line is divided into a fault point upstream section (comprising detection points 1# and 2#), a fault point downstream trunk section (comprising detection points 3#, 4#, and 5 #) and a fault point downstream branch section (comprising detection point b2#) according to the section of the fault point.
Fitting the power frequency zero sequence voltage information of a limited number of detection points into a curve reflecting the whole power frequency zero sequence voltage distribution condition of the fault line by using a curve fitting method, and firstly taking the electrical distance from a bus as an abscissa x and a power frequency zero sequence voltage amplitude value U0(x) Establishing a two-dimensional coordinate system reflecting the power frequency zero sequence voltage distribution conditions of the upstream and downstream of the fault point for the ordinate, and fitting the data of the detection points in the table 1 into a linear function curve by using the data of the 1# and 2# detection points, wherein the linear function curve is obtained by using the data of the 1# and 2# detection points
Then the power frequency zero sequence voltage distribution curve of the upstream section of the fault point is:
U0(x)＝1.425x+8439.1
fitting the downstream section of the fault point to a quadratic function curve by using the data of the 3#, 4#, and 5# detection points, wherein
Then
Then the power frequency zero sequence voltage distribution curve of the downstream main section of the fault point is:
U0(x)＝-0.0083x2+0.3167x+8446.1
the two fitted power frequency zero sequence voltage distribution curves are shown as a solid line in figure 7, the upper and lower distribution curves are combined to calculate the curve intersection point,
the two curves are solved to obtain a unique intersection point in the first quadrant, as shown by a dotted line in fig. 7, the coordinate of the intersection point is (6.04km,8447.7V), the abscissa of the intersection point is about 6.04km, and the calculated fault point is located on the trunk line 6.04km away from the bus.
A branch is provided at a position 6km away from a bus line of a trunk line, a position determined in the judgment of the fault of the trunk line is 0.04km < 0.1km away from the branch point, and the fault judgment of the branch line should be further performed because the fault point is likely to be located on the branch line because the distance measurement result is very close to the branch line in consideration of the error.
The same as the main line fault judgment, the power frequency zero sequence voltage distribution curve of the upstream section of the fault point is fitted into a linear function curve by using the 1# and 2# detection point information: u shape0(x)＝1.425x+8439.1。
Fitting a power frequency zero sequence voltage distribution curve of a downstream section of the fault point into a constant function by using b2# detection point information: u shape0(x)＝8449.7。
The two fitted power frequency zero sequence voltage distribution curves are shown as a solid line in figure 8, the upper and lower distribution curves are combined to calculate the curve intersection point,
the two curves are solved to obtain a unique intersection point in the first quadrant, as shown by the dotted line in fig. 8, the coordinate of the intersection point is (7.44km,8449.7V), the abscissa of the intersection point is about 7.44km, i.e. the calculated fault point is located 1.44km (7.44km-6km) extending outward from the branch line at a distance of 6km from the bus.
The difference between the final ranging result and the actually set fault point position is only 0.06km, the error is small, and the accuracy requirement of actual application can be met. (note: x takes two digits after decimal point in the solving process, thus resulting in U in reverse checking calculation0(x) Deviation of (2) is a normal phenomenon
The disclosure of the present application also includes the following points:
(1) the embodiments disclosed in the present application are only examples, and the technical solutions implemented by other equivalent technical means belong to the scope of protection of the present application;
(2) the technical features disclosed in the present application may be combined with each other to obtain new embodiments, without conflict;
the above embodiments are only examples disclosed in the present application, but the scope of the present disclosure is not limited thereto, and those skilled in the art should, in light of the present disclosure, modify and change some of the technical features of the present disclosure within the scope of the present application.
Claims (10)
1. A small current grounding fault distance measuring method of a power distribution network resonance grounding system is characterized in that,
the method comprises the following steps:
s1: distributing a plurality of power distribution terminals on a power distribution network line, and acquiring real-time power frequency zero-sequence voltage information of a fault line and section information of a fault point when a small current ground fault occurs in a resonant grounding system;
s2: dividing a fault line into a fault point upstream section, a fault point downstream main section and a fault point downstream branch section according to the section information of the fault point;
s3: respectively fitting power frequency zero-sequence voltage information of the power distribution terminal into a power frequency zero-sequence voltage distribution curve of an upstream section of a fault point and a power frequency zero-sequence voltage distribution curve of a downstream trunk section of the fault point by using a curve fitting method, and solving a curve intersection point to determine the position of the fault point on a trunk line;
s4: if the distance between the fault position determined in the step S3 and the branch point does not exceed E, the flow proceeds to a step S5;
if the distance between the fault position determined in the step S3 and the branch point is larger than E, finishing ranging;
s5: and respectively fitting the power frequency zero-sequence voltage information of the power distribution terminal into a power frequency zero-sequence voltage distribution curve of an upstream section of the fault point and a power frequency zero-sequence voltage distribution curve of a downstream branch section of the fault point by using a curve fitting method, and solving a curve intersection point to determine the position of the fault point on the branch line.
2. The method for ranging the small-current ground fault of the resonance grounding system of the power distribution network according to claim 1, wherein in the step S1, the distribution terminals are arranged according to a method comprising:
main line layout: extending outwards by a bus, and arranging a power distribution terminal every time when the bus passes through a distance of at most P;
branch line layout: extending outwardly at a branch point, one distribution terminal is provided for each distance of up to Q.
3. The power distribution network resonance grounding system small current grounding fault distance measuring method according to claim 2, characterized in that in the main line layout, the power distribution terminal is directly arranged on the main line or arranged on the branch line with the distance of at most Q from the branch point.
4. The method for ranging the small current ground fault of the resonance grounding system of the power distribution network according to claim 1, wherein the processing of the power distribution terminal on the branch line in the step S3 is as follows:
if a branched power distribution terminal is arranged between the bus and the fault point, the branched line is ignored;
if a branch power distribution terminal exists between the fault point and the load, the distance between the scoring fulcrum and the bus is m, and the distance between the branch power distribution terminal and the branching point is n, the branch power distribution terminal is planned to be positioned on a main section which is m + n away from the bus.
5. The small-current ground fault distance measuring method for the power distribution network resonance ground system according to claim 1, wherein the fitting method of the power frequency zero sequence voltage distribution curve of the section at the upstream of the fault point, the power frequency zero sequence voltage distribution curve of the main section at the downstream of the fault point and the power frequency zero sequence voltage distribution curve of the branch section at the downstream of the fault point comprises the following steps:
taking the distance x from a fault point to a bus as an abscissa, and taking the power frequency zero sequence voltage amplitude U at the position of x0(x) For the ordinate, the distribution curve of the power frequency zero sequence voltage is established as follows:
U0(x)＝ax2+bx+c (1)
wherein a, b and c are respectively a quadratic coefficient, a primary coefficient and a constant.
6. The small-current ground fault location method for the power distribution network resonance grounding system as claimed in claim 5, wherein when fitting the curve, each power distribution terminal is used as a detection point to provide the required power frequency zero sequence voltage information, wherein,
the number of detection points of the upstream section of the fault point is more than or equal to 2, and the number of detection points of the downstream main section of the fault point is more than or equal to 1;
if the section where the fault point is located is provided with branches, the number of detection points of the branch section at the downstream of the fault point is more than or equal to 1.
7. The small-current ground fault location method for the power distribution network resonant grounding system according to claim 6, wherein when the number of the detection points is 1, let a-b-0 and U-00(x) Fitting as a constant function, i.e.
U0(x)＝c (2)。
8. The small-current ground fault location method for the power distribution network resonant grounding system according to claim 6, wherein when the number of the detection points is 2, let a be 0, U0(x) Fitting as a linear function, i.e.
U0(x)＝bx+c (3)；
Let the detection point data be (x)1,U0(x1)),(x2,U0(x2) Substituting formula (3) to obtain
9. The small-current ground fault distance measurement method for power distribution network resonance grounding system according to claim 6, wherein when the number of detection points is 3, U is measured0(x) Fitting into a quadratic function, and setting the detection point data as (x)1,U0(x1))、(x2,U0(x2))、(x3,U0(x3) Substituting the formula (1),
order to
Then
10. The small-current ground fault distance measurement method for resonance grounding system of power distribution network according to claim 6, wherein when the number of detection points is greater than 3, U is measured0(x) Fitting into a quadratic function, and setting the detection point data as
According to the formula (1), the mean square error formula of a, b and c is obtained as
Using the minimum mean square error as the constraint condition, the solving formula of a, b and c is
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114384376A (en) * | 2022-03-23 | 2022-04-22 | 浙江浙能能源服务有限公司 | Fault classification positioning method for direct-current power distribution network |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102043113A (en) * | 2009-10-22 | 2011-05-04 | 上海思南电力通信有限公司 | Method for locating single phase ground fault locating system |
| CN103792465A (en) * | 2013-12-24 | 2014-05-14 | 中国矿业大学 | Power distribution network one-phase grounding fault location method based on zero sequence voltage |
| WO2014089899A1 (en) * | 2012-12-10 | 2014-06-19 | 国家电网公司 | Distribution network phase-to-earth fault location method and location device based on transient signal wavelet transformation |
| CN107884682A (en) * | 2017-11-23 | 2018-04-06 | 国网山东省电力公司枣庄供电公司 | Electrical power distribution network fault location method based on trouble point Yu monitoring point distance |
| CN110703036A (en) * | 2019-10-09 | 2020-01-17 | 江苏方天电力技术有限公司 | Clustering-based high-resistance grounding fault positioning method for resonant grounding system |
-
2021
- 2021-07-09 CN CN202110779416.8A patent/CN113466628A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102043113A (en) * | 2009-10-22 | 2011-05-04 | 上海思南电力通信有限公司 | Method for locating single phase ground fault locating system |
| WO2014089899A1 (en) * | 2012-12-10 | 2014-06-19 | 国家电网公司 | Distribution network phase-to-earth fault location method and location device based on transient signal wavelet transformation |
| CN103792465A (en) * | 2013-12-24 | 2014-05-14 | 中国矿业大学 | Power distribution network one-phase grounding fault location method based on zero sequence voltage |
| CN107884682A (en) * | 2017-11-23 | 2018-04-06 | 国网山东省电力公司枣庄供电公司 | Electrical power distribution network fault location method based on trouble point Yu monitoring point distance |
| CN110703036A (en) * | 2019-10-09 | 2020-01-17 | 江苏方天电力技术有限公司 | Clustering-based high-resistance grounding fault positioning method for resonant grounding system |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114384376A (en) * | 2022-03-23 | 2022-04-22 | 浙江浙能能源服务有限公司 | Fault classification positioning method for direct-current power distribution network |
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