CN114217173A - Single-phase fault line selection and location method, device and equipment for small current grounded distribution network - Google Patents
Single-phase fault line selection and location method, device and equipment for small current grounded distribution network Download PDFInfo
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Abstract
The invention relates to a method, a device and equipment for selecting and positioning single-phase faults of a small-current grounding power distribution network, wherein the method is characterized in that the method collects the electric quantity data of lines through measuring equipment and is not limited by sampling frequency, so that the method for selecting and positioning the single-phase faults of the small-current grounding power distribution network has a wide application range; the electric quantity data collected by each measuring device is analyzed through a zero sequence characteristic calculation formula to obtain a plurality of zero sequence characteristic quantities of the measuring device, the maximum zero sequence characteristic quantity is selected from the zero sequence characteristic quantities for comparative analysis to obtain comparative setting values of two adjacent measuring terminals, and the comparative setting values are compared with a preset setting threshold value to obtain a fault line, so that the fault location of the method is not influenced by transition resistance, the accurately located fault line is still obtained under the condition of weak fault, and the reliability is higher; the method solves the problems that the traditional line selection and positioning method is adopted for positioning the power distribution network line fault, and the positioning method has large positioning error and low reliability.
Description
Technical Field
The invention relates to the technical field of power distribution networks, in particular to a method, a device and equipment for selecting and positioning single-phase faults of a low-current grounding power distribution network.
Background
The distribution network is the tail end of a power grid and is directly connected with users, the voltage level is low, the line density is high, the operation environment is complex, the maintenance is difficult, the factors causing faults are many, and the faults are frequent. Once the distribution network fails, the protection selectivity is poor, and the isolation range is large; the method is influenced by the network topology, short circuit and many branches of the distribution network, the fault positioning precision is poor, the power failure time is long, and the power supply reliability is seriously influenced. For example: if the number of faults of the public feeder line of the Guangdong power grid is 37524, the average power failure time (medium voltage) of a fault client is 5.92 hours, the faults of the distribution network occur frequently, the fault location is inaccurate, and the equipment safety, the external personnel safety and the power supply reliability to the user are seriously influenced.
Aiming at the problems of line selection and positioning of single-phase earth faults of a power distribution network, particularly for a low-current earthing system of the power distribution network such as a mode that neutral points adopted by a medium-low voltage power distribution network in a large quantity are earthed through arc suppression coils, fault characteristics related to zero sequence current are eliminated under the action of the arc suppression coils, so that fault identification and positioning based on steady-state fault characteristics are more difficult, and the fault can be removed only within a long time for protection, so that the steady-state characteristics of the low-current earthing system of the power distribution network are not obvious, and the fault transient process is closely related to fault characteristics such as line topology, line capacitance distribution and fault point positions.
Therefore, in the existing research, transient information is usually adopted to locate a fault section, and the traditional line selection and location methods include a zero-sequence current method, a medium resistance method, a zero-sequence power direction method, an injection method, an impedance method, a traveling wave method and the like. The traditional line selection and positioning methods have defects which can not meet the requirements, and the defects are as follows: the small current grounding system of the traditional power distribution network usually adopts a traveling wave method to carry out fault line selection and fault location, and the location method can adapt to various fault conditions theoretically, but even under the sampling frequency of up to 1MHz, the traveling wave propagation distance between adjacent sampling points is still up to 300m, so that a larger location error is caused, and the requirement of the method on the sampling frequency is extremely high. And the traditional traveling wave method is divided into a single-ended traveling wave method and a double-ended traveling wave method, wherein the single-ended traveling wave method needs to accurately identify a second reflected traveling wave head and is difficult to identify when a topological structure of a line is complex and weak faults occur, the double-ended method needs to arrange power distribution automatic terminals with traveling wave acquisition functions at two ends of each section of the line, when distribution network branch lines are more and the structure is complex, the terminal arrangement is difficult to consider both effects and cost, the benefit is low, and the method is difficult to be applied to distribution network application scenes with sensitive cost. On the other hand, the algorithm in the traditional line selection and positioning method is greatly influenced by transition resistance, when weak faults such as single-phase grounding, high-resistance grounding and the like occur, the fault characteristics are not obvious enough, and the reliability of fault line selection and positioning is low.
Disclosure of Invention
The embodiment of the invention provides a method, a device and equipment for selecting and positioning a single-phase fault of a low-current grounding power distribution network, which are used for solving the technical problems of large positioning error and low reliability of the conventional method for selecting and positioning the fault of a power distribution network line.
In order to achieve the above object, the embodiments of the present invention provide the following technical solutions:
a single-phase fault line selection and positioning method for a low-current grounding power distribution network is applied to a low-current grounding system of the power distribution network, a plurality of main lines are arranged on the power distribution network, a plurality of branch lines are arranged on each main line, measuring equipment is arranged at two ends of each main line and each branch line, and if the single-phase grounding fault occurs in the low-current grounding system of the power distribution network, the single-phase fault line selection and positioning method for the low-current grounding power distribution network comprises the following steps:
acquiring electrical quantity data of each main line at n moments by each measuring device within set time;
calculating each electric quantity data by adopting a zero sequence characteristic calculation formula to obtain n zero sequence characteristic quantities corresponding to each measuring device;
acquiring a zero-sequence characteristic quantity with the largest numerical value from the n zero-sequence characteristic quantities of each measuring device as the largest zero-sequence characteristic quantity of the measuring device, and comparing the largest zero-sequence characteristic quantities of two adjacent measuring devices to obtain K comparison setting values;
analyzing each comparison setting value, and if the comparison setting value is larger than a preset setting threshold value, determining that the fault line is a main line between two measuring devices corresponding to the comparison setting value;
wherein, the zero sequence characteristic calculation formula is as follows:
wherein P (T) is zero sequence characteristic quantity of measuring equipment at time T, T0For the power frequency period, i (T) is the zero sequence current collected by the measuring equipment at the moment T, u (T) is the zero sequence voltage collected by the measuring equipment at the moment T, and u (T + T)0) Is T + T0Zero sequence voltage i (T + T) collected by the time measurement equipments) Is T + TsZero sequence current, T, collected by a time measurement devicesAcquiring the quantity of electrical quantity data for the measuring equipment, namely n, K is the quantity of line sections of the main line, i (j) is the zero sequence current acquired by the measuring equipment at the jth moment, and j belongs to n.
Preferably, if the fault line is a main line between the two measuring devices corresponding to the comparison setting value, the method for selecting and positioning the single-phase fault of the low-current grounding distribution network comprises the following steps:
collecting branch electrical quantity data of each branch line at m moments through each measuring device;
calculating each branch electric quantity data by adopting a zero sequence characteristic calculation formula to obtain m branch zero sequence characteristic quantities corresponding to each measuring device;
acquiring zero-sequence characteristic quantity with the largest numerical value from m branch zero-sequence characteristic quantities of each measuring device as the largest branch zero-sequence characteristic quantity of the measuring device, and comparing the largest branch zero-sequence characteristic quantities of two adjacent measuring devices to obtain g branch comparison setting values;
analyzing each branch comparison setting value;
if the branch comparison setting value is larger than a preset setting threshold value, the fault line is a branch line between two measuring devices corresponding to the branch comparison setting value;
wherein m is 3.5TsAnd g is the number of line segments of the branch line.
Preferably, the method for selecting and positioning the single-phase fault of the low-current grounding power distribution network comprises the following steps: and if all the branch comparison setting values are smaller than a preset setting threshold value, the fault line is a main line corresponding to the branch line.
Preferably, the method for selecting and positioning the single-phase fault of the low-current grounding power distribution network comprises the following steps: comparing and analyzing the maximum zero sequence characteristic quantity of two adjacent measuring devices through a comparison and analysis formula, wherein the comparison and analysis formula is as follows:
Ka,b＝max[Pa]/max[Pb]；
in the formula, max [ Pa]Maximum zero sequence characteristic quantity, max [ P ], for the a-th measuring deviceb]For the maximum zero sequence characteristic quantity, K, of the b-th measuring devicea，bAnd a and b are natural numbers which are greater than 0 and are used for comparison setting values between the a measuring device and the b measuring device.
Preferably, the electrical quantity data comprises at least a zero sequence current and a zero sequence voltage.
The invention also provides a single-phase fault line selection and positioning device for the low-current grounding power distribution network, which is applied to a low-current grounding system of the power distribution network, wherein a plurality of main lines are arranged on the power distribution network, a plurality of branch lines are arranged on each main line, measuring equipment is arranged at two ends of each main line and each branch line, and if the single-phase grounding fault occurs in the low-current grounding system of the power distribution network, the single-phase fault line selection and positioning device for the low-current grounding power distribution network comprises: the device comprises a data acquisition module, a calculation module, a comparison module and a positioning output module;
the data acquisition module is used for acquiring the electrical quantity data of each main line at n moments through each measuring device within set time;
the calculation module is configured to calculate each electrical quantity data by using a zero sequence characteristic calculation formula to obtain n zero sequence characteristic quantities corresponding to the measurement devices;
the comparison module is configured to obtain a zero-sequence characteristic quantity with a largest numerical value from the n zero-sequence characteristic quantities of each measurement device, and compare the largest zero-sequence characteristic quantities of two adjacent measurement devices to obtain K comparison setting values;
the positioning output module is used for analyzing each comparison setting value, and if the comparison setting value is larger than a preset setting threshold value, the fault line is a main line between two measuring devices corresponding to the comparison setting value;
wherein, the zero sequence characteristic calculation formula is as follows:
wherein P (T) is zero sequence characteristic quantity of measuring equipment at time T, T0For the power frequency period, i (T) is the zero sequence current collected by the measuring equipment at the moment T, u (T) is the zero sequence voltage collected by the measuring equipment at the moment T, and u (T + T)0) Is T + T0Zero sequence voltage i (T + T) collected by the time measurement equipments) Is T + TsZero sequence current, T, collected by a time measurement devicesAcquiring the quantity of electrical quantity data for the measuring equipment, namely n, K is the quantity of line sections of the main line, i (j) is the zero sequence current acquired by the measuring equipment at the jth moment, and j belongs to n.
Preferably, the positioning output module comprises a branch acquisition sub-module, a branch calculation sub-module, a branch comparison sub-module and a branch output sub-module;
the branch acquisition submodule is used for acquiring branch electrical quantity data of each branch line at m moments through each measuring device;
the branch calculation submodule is used for calculating each branch electric quantity data by adopting a zero-sequence characteristic calculation formula to obtain m branch zero-sequence characteristic quantities corresponding to each measuring device;
the branch comparison submodule is used for obtaining a zero-sequence characteristic quantity with a maximum value from m branch zero-sequence characteristic quantities of each measuring device as a maximum branch zero-sequence characteristic quantity of the measuring device, and comparing the maximum branch zero-sequence characteristic quantities of two adjacent measuring devices to obtain g branch comparison setting values;
the branch output submodule is used for analyzing each branch comparison setting value; if the branch comparison setting value is larger than a preset setting threshold value, the fault line is a branch line between two measuring devices corresponding to the branch comparison setting value;
wherein m is 3.5TsAnd g is the number of line segments of the branch line.
Preferably, the branch output sub-module is further configured to determine that the faulty line is a main line corresponding to the branch line if all the branch comparison setting values are smaller than a preset setting threshold value.
Preferably, the comparison module is further configured to compare and analyze the maximum zero sequence characteristic quantity of two adjacent metrology devices by using a comparison and analysis formula, where the comparison and analysis formula is:
Ka,b＝max[Pa]/max[Pb]；
in the formula, max [ Pa]Maximum zero sequence characteristic quantity, max [ P ], for the a-th measuring deviceb]For the maximum zero sequence characteristic quantity, K, of the b-th measuring devicea，bAnd a and b are natural numbers which are greater than 0 and are used for comparison setting values between the a measuring device and the b measuring device.
The invention also provides a single-phase fault line selection and positioning device of the low-current grounding power distribution network, which comprises a processor and a memory;
the memory is used for storing program codes and transmitting the program codes to the processor;
the processor is used for executing the single-phase fault line selection and positioning method of the low-current grounding power distribution network according to the instructions in the program codes.
According to the technical scheme, the embodiment of the invention has the following advantages: the method, the device and the equipment for selecting and positioning the single-phase fault of the small-current grounding power distribution network comprise the following steps: acquiring electrical quantity data of each main line at n moments by each measuring device within set time; calculating each electric quantity data by adopting a zero sequence characteristic calculation formula to obtain n zero sequence characteristic quantities corresponding to each measuring device; acquiring a zero-sequence characteristic quantity with the largest numerical value from the n zero-sequence characteristic quantities of each measuring device as the largest zero-sequence characteristic quantity of the measuring device, and comparing the largest zero-sequence characteristic quantities of two adjacent measuring devices to obtain K comparison setting values; and analyzing each comparison setting value, and if the comparison setting value is greater than a preset setting threshold value, the fault line is a main line between two measuring devices corresponding to the comparison setting value. The single-phase earth fault line selection and positioning method is characterized in that the single-phase earth fault line selection and positioning method is free from the limitation of sampling frequency by acquiring the electric quantity data of the line through the measuring equipment, so that the single-phase earth fault line selection and positioning method of the small-current earth distribution network is wide in application range; analyzing the electric quantity data acquired by each measuring device through a zero sequence characteristic calculation formula to obtain a plurality of zero sequence characteristic quantities of the measuring device, selecting the maximum zero sequence characteristic quantity from the zero sequence characteristic quantities for comparative analysis to obtain comparative setting values of two adjacent measuring terminals, and comparing the comparative setting values with a preset setting threshold value to obtain a fault line, so that the fault location of the method for selecting and locating the single-phase fault line of the small-current grounding power distribution network is not influenced by transition resistance, the accurately located fault line is still obtained under the condition of weak fault, and the reliability is higher; the method solves the technical problems that the traditional line selection and positioning method is adopted in the existing power distribution network line fault positioning, the positioning error is large, and the reliability is low.
Drawings
In order to more clearly illustrate the embodiments of the present invention 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 that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 is a flowchart illustrating steps of a method for selecting and positioning a single-phase fault of a low-current grounded power distribution network according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a power distribution network installation measuring device in the small-current grounding power distribution network single-phase fault line selection and positioning method according to the embodiment of the invention;
fig. 3 is a block diagram of a single-phase fault line selection and positioning device for a low-current grounding distribution network according to an embodiment of the invention.
Detailed Description
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below are only a part of the embodiments of the present invention, 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 invention.
The embodiment of the application provides a method, a device and equipment for selecting and positioning a single-phase fault of a low-current grounding power distribution network, which are applied to a low-current grounding system of the power distribution network and used for solving the technical problems that the positioning error is large and the reliability is low in the conventional method for positioning the line fault of the power distribution network.
The first embodiment is as follows:
fig. 1 is a flowchart illustrating steps of a method for selecting and positioning a single-phase fault of a low-current grounded power distribution network according to an embodiment of the present invention, and fig. 2 is a schematic structural diagram illustrating a power distribution network installation measurement device in the method for selecting and positioning a single-phase fault of a low-current grounded power distribution network according to an embodiment of the present invention.
As shown in fig. 2, an embodiment of the present invention provides a single-phase fault line selection and positioning method for a low-current grounding power distribution network, which is applied to a low-current grounding system of a power distribution network, wherein a plurality of main lines are arranged on the power distribution network, a plurality of branch lines are arranged on each main line, and measuring devices 10 are installed at two ends of each main line and each branch line.
It should be noted that the measuring equipment mainly collects data of electrical quantities on the main line and the branch line. In the present embodiment, the electrical quantity data includes at least voltage, current, power, and the like. The measuring equipment can be a situation perception control terminal and can also be a sensor. According to the method for selecting and positioning the single-phase fault of the small-current grounding power distribution network, the situation perception control terminal or the sensor of the power distribution network is arranged on the main line and the important branch line of the power distribution network, the sensors are arranged on other branch line lines, the conditions that the number of the branch lines of the power distribution network is large and the structure is complex are effectively met, and the accurate positioning of the single-phase fault of the small-current grounding power distribution network is realized.
As shown in fig. 1, if a single-phase earth fault occurs in a low-current earth system of a power distribution network, the method for selecting and positioning the single-phase fault of the low-current earth power distribution network comprises the following steps:
s1, collecting electrical quantity data of each main line at n moments through each measuring device within set time.
It should be noted that the electric quantity data at each time is collected by the throughput device mainly within a set time. In this embodiment, if the set time is 70ms, t is the time from0Starting to collect the electric quantity data, and then collecting the electric quantity data once every other power frequency period, so that t is the period from t0And acquiring n electrical quantity data within 70 ms. In the method for selecting and positioning the single-phase fault of the small-current grounding power distribution network, two electric quantity data of zero-sequence current and zero-sequence voltage are mainly acquired by a measuring device.
In the embodiment of the invention, the single-phase fault line selection and positioning method for the small-current grounding power distribution network is characterized in that the electric quantity data of the line is acquired by the measuring equipment, the requirement on the sampling frequency acquired by the measuring equipment is not high, and the single-phase fault line selection and positioning method for the small-current grounding power distribution network is wide in application range and is not limited by the sampling frequency.
And S2, calculating each electric quantity data by adopting a zero sequence characteristic calculation formula to obtain n zero sequence characteristic quantities corresponding to each measuring device.
In step S2, the zero sequence characteristic quantities at n times corresponding to the measurement devices are calculated by using a zero sequence characteristic calculation formula according to the electrical quantity data acquired in step S1. The method for selecting and positioning the single-phase fault of the small-current grounding power distribution network is obtained by calculating the zero-sequence characteristic quantity of each measuring device only through self zero-sequence voltage and zero-sequence current, and the requirement on time synchronization of sampling data of the measuring devices at two ends of a line is reduced.
In the embodiment of the invention, the zero sequence characteristic calculation formula is as follows:
wherein P (T) is zero sequence characteristic quantity of measuring equipment at time T, T0For the power frequency period, i (T) is the zero sequence current collected by the measuring equipment at the moment T, u (T) is the zero sequence voltage collected by the measuring equipment at the moment T, and u (T + T)0) Is T + T0Zero sequence voltage i (T + T) collected by the time measurement equipments) Is T + TsZero sequence current, T, collected by a time measurement devicesAnd acquiring the quantity of the electric quantity data for the measuring equipment, namely n, i (j) is zero sequence current acquired by the measuring equipment at the jth moment, and j belongs to n.
S3, acquiring the zero sequence characteristic quantity with the largest numerical value from the n zero sequence characteristic quantities of each measuring device as the largest zero sequence characteristic quantity of the measuring device, and comparing the largest zero sequence characteristic quantities of two adjacent measuring devices to obtain K comparison setting values.
It should be noted that, the maximum zero sequence characteristic quantity of all zero sequence characteristic quantities in each measurement terminal is mainly selected to provide data for comparison and analysis of two adjacent measurement devices, and K is the number of line sections of the main line.
And S4, analyzing each comparison setting value, and if the comparison setting value is larger than a preset setting threshold value, determining that the fault line is a main line between two measuring devices corresponding to the comparison setting value.
It should be noted that, mainly according to the K comparison setting values obtained in step S3, each comparison setting value is compared with a preset setting threshold value, and only if the comparison setting value is greater than the preset setting threshold value, it is indicated that the faulty line is on the main line between the two measurement devices corresponding to the comparison setting value, so as to achieve positioning of the faulty line. In this embodiment, the preset setting threshold may be set according to a requirement, and is not limited herein.
The invention provides a single-phase fault line selection and positioning method for a low-current grounding power distribution network, which comprises the following steps: acquiring electrical quantity data of each main line at n moments by each measuring device within set time; calculating each electric quantity data by adopting a zero sequence characteristic calculation formula to obtain n zero sequence characteristic quantities corresponding to each measuring device; acquiring a zero-sequence characteristic quantity with the largest numerical value from the n zero-sequence characteristic quantities of each measuring device as the largest zero-sequence characteristic quantity of the measuring device, and comparing the largest zero-sequence characteristic quantities of two adjacent measuring devices to obtain K comparison setting values; and analyzing each comparison setting value, and if the comparison setting value is greater than a preset setting threshold value, the fault line is a main line between two measuring devices corresponding to the comparison setting value. The single-phase earth fault line selection and positioning method is characterized in that the single-phase earth fault line selection and positioning method is free from the limitation of sampling frequency by acquiring the electric quantity data of the line through the measuring equipment, so that the single-phase earth fault line selection and positioning method of the small-current earth distribution network is wide in application range; analyzing the electric quantity data acquired by each measuring device through a zero sequence characteristic calculation formula to obtain a plurality of zero sequence characteristic quantities of the measuring device, selecting the maximum zero sequence characteristic quantity from the zero sequence characteristic quantities for comparative analysis to obtain comparative setting values of two adjacent measuring terminals, and comparing the comparative setting values with a preset setting threshold value to obtain a fault line, so that the fault location of the method for selecting and locating the single-phase fault line of the small-current grounding power distribution network is not influenced by transition resistance, the accurately located fault line is still obtained under the condition of weak fault, and the reliability is higher; the method solves the technical problems that the traditional line selection and positioning method is adopted in the existing power distribution network line fault positioning, the positioning error is large, and the reliability is low.
The method for selecting and positioning the single-phase fault of the low-current grounding power distribution network also transmits the obtained fault line to a master station of the power distribution network, the master station directly receives the fault positioning result, and the data volume of the fault positioning result transmitted by the method for selecting and positioning the single-phase fault of the low-current grounding power distribution network is small and the communication requirement is low.
It should be noted that the obtained fault line may be transmitted to the master station of the power distribution network by 4G, 5G, or optical fiber, and the master station may synthesize the network topology according to the calculation result of the characteristic quantity of each measurement terminal, and perform fault line selection and location in a centralized manner. The zero sequence characteristic quantity calculation method is not influenced by the limitation of sampling frequency and transition resistance, so that the application range of the single-phase fault line selection and positioning method of the small-current grounding power distribution network is wide; in the method, each terminal characteristic quantity is obtained only through self zero sequence voltage and zero sequence current calculation, so that the requirement on time synchronization of terminals at two ends of a line is reduced; in the method, each terminal only needs to transmit the calculation result of the characteristic quantity to the master station, so that the transmission data volume is small and the communication requirement is low; the deployment mode provided by the method can effectively deal with the conditions of more distribution network branch lines and complex structure, and has better economy.
In an embodiment of the present invention, if the fault line is a main line between two measurement devices corresponding to the comparison setting value, the method for selecting and positioning a single-phase fault of the low-current grounded power distribution network includes:
collecting branch electrical quantity data of each branch line at m moments through each measuring device;
calculating the electrical quantity data of each branch by adopting a zero sequence characteristic calculation formula to obtain m branch zero sequence characteristic quantities corresponding to each measuring device;
acquiring zero-sequence characteristic quantity with the largest numerical value from m branch zero-sequence characteristic quantities of each measuring device as the largest branch zero-sequence characteristic quantity of the measuring device, and comparing the largest branch zero-sequence characteristic quantities of two adjacent measuring devices to obtain g branch comparison setting values;
analyzing the comparison setting value of each branch;
if the branch comparison setting value is larger than the preset setting threshold value, the fault line is a branch line between two measuring devices corresponding to the branch comparison setting value;
wherein m is 3.5TsAnd g is the number of line segments of the branch line.
In the embodiment of the invention, the method for selecting and positioning the single-phase fault of the low-current grounding power distribution network comprises the following steps: and if the comparison setting values of all the branches are smaller than the preset setting threshold value, the fault line is the main line corresponding to the branch line.
When it is determined in step S4 which main line is the faulty line, it is determined whether the fault is on which branch line or main line of the main line by the same method as the main line fault location method.
In one embodiment of the invention, the method for selecting and positioning the single-phase fault of the low-current grounding power distribution network comprises the following steps: the maximum zero sequence characteristic quantity of two adjacent measurement devices is compared and analyzed through a comparison and analysis formula, wherein the comparison and analysis formula is as follows:
Ka,b＝max[Pa]/max[Pb]；
in the formula, max [ Pa]Maximum zero sequence characteristic quantity, max [ P ], for the a-th measuring deviceb]For the maximum zero sequence characteristic quantity, K, of the b-th measuring devicea，bAnd a and b are natural numbers which are greater than 0 and are used for comparison setting values between the a measuring device and the b measuring device. Wherein a is not equal to b.
It should be noted that the calculation process of comparing the setting values is mainly obtained by comparing the maximum zero sequence characteristic quantities of two adjacent measurement devices through a comparative analysis formula.
Example two:
fig. 3 is a block diagram of a single-phase fault line selection and positioning device for a low-current grounding distribution network according to an embodiment of the invention.
As shown in fig. 3, an embodiment of the present invention further provides a single-phase fault line selection and positioning device for a low-current grounding power distribution network, which is applied to a low-current grounding system of a power distribution network, wherein a plurality of main lines are arranged on the power distribution network, a plurality of branch lines are arranged on each main line, measuring devices are installed at two ends of each main line and each branch line, and if a single-phase grounding fault occurs in the low-current grounding system of the power distribution network, the single-phase fault line selection and positioning device for the low-current grounding power distribution network includes: the system comprises a data acquisition module 10, a calculation module 20, a comparison module 30 and a positioning output module 40;
the data acquisition module 10 is configured to acquire electrical quantity data of each main line at n times through each measurement device within a set time;
the calculating module 20 is configured to calculate each electrical quantity data by using a zero sequence characteristic calculating formula to obtain n zero sequence characteristic quantities corresponding to each measuring device;
the comparison module 30 is configured to obtain a zero-sequence characteristic quantity with a largest numerical value from the n zero-sequence characteristic quantities of each measurement device, and compare the largest zero-sequence characteristic quantities of two adjacent measurement devices to obtain K comparison setting values;
the positioning output module 40 is used for analyzing each comparison setting value, and if the comparison setting value is greater than a preset setting threshold value, the fault line is a main line between two measuring devices corresponding to the comparison setting value;
wherein, the zero sequence characteristic calculation formula is as follows:
wherein P (T) is zero sequence characteristic quantity of measuring equipment at time T, T0For the power frequency period, i (T) is the zero sequence current collected by the measuring equipment at the moment T, u (T) is the zero sequence voltage collected by the measuring equipment at the moment T, and u (T + T)0) Is T + T0Zero sequence voltage i (T + T) collected by the time measurement equipments) Is T + TsZero sequence current, T, collected by a time measurement devicesAcquiring the quantity of electric quantity data for measuring equipment, namely n, i (j) is zero-sequence current acquired by the measuring equipment at the jth moment, and j belongs to n;
wherein K is the number of line sections of the main line.
In the embodiment of the present invention, the positioning output module 40 includes a branch acquisition sub-module, a branch calculation sub-module, a branch comparison sub-module and a branch output sub-module;
the branch acquisition submodule is used for acquiring branch electrical quantity data of each branch line at m moments through each measuring device;
the branch calculation submodule is used for calculating each branch electric quantity data by adopting a zero-sequence characteristic calculation formula to obtain m branch zero-sequence characteristic quantities corresponding to each measuring device;
the branch comparison submodule is used for acquiring zero-sequence characteristic quantity with the largest numerical value from m branch zero-sequence characteristic quantities of each measuring device as the largest branch zero-sequence characteristic quantity of the measuring device, and comparing the largest branch zero-sequence characteristic quantities of two adjacent measuring devices to obtain g branch comparison setting values;
the branch output submodule is used for analyzing the comparison setting value of each branch; if the branch comparison setting value is larger than the preset setting threshold value, the fault line is a branch line between two measuring devices corresponding to the branch comparison setting value;
wherein m is 3.5TsAnd g is the number of line segments of the branch line.
In the embodiment of the present invention, the branch output sub-module is further configured to compare, by all branches, that the setting value is smaller than the preset setting threshold value, and determine that the faulty line is the main line corresponding to the branch line.
In the embodiment of the present invention, the comparing module is further configured to compare and analyze the maximum zero sequence characteristic quantity of the two adjacent measurement devices through a comparison and analysis formula, where the comparison and analysis formula is:
Ka,b＝max[Pa]/max[Pb]；
in the formula, max [ Pa]Maximum zero sequence characteristic quantity, max [ P ], for the a-th measuring deviceb]For the maximum zero sequence characteristic quantity, K, of the b-th measuring devicea，bA and b are natural numbers larger than 0 for comparison setting value between the a measurement device and the b measurement device。
It should be noted that the modules in the second embodiment correspond to the steps in the first embodiment, and the steps in the first embodiment have been described in detail in the first embodiment, and the contents of the modules in the second embodiment are not described in detail in this second embodiment.
Example three:
the embodiment of the invention provides a single-phase fault line selection and positioning device for a low-current grounding power distribution network, which comprises a processor and a memory, wherein the processor is used for processing a fault signal;
a memory for storing the program code and transmitting the program code to the processor;
and the processor is used for executing the single-phase fault line selection and positioning method of the low-current grounding power distribution network according to instructions in the program codes.
It should be noted that, the processor is configured to execute the steps in the embodiment of the method for selecting and positioning a single-phase fault of a low-current grounded power distribution network according to the instructions in the program code. Alternatively, the processor, when executing the computer program, implements the functions of each module/unit in each system/apparatus embodiment described above.
Illustratively, a computer program may be partitioned into one or more modules/units, which are stored in a memory and executed by a processor to accomplish the present application. One or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution of a computer program in a terminal device.
The terminal device may be a desktop computer, a notebook, a palm computer, a cloud server, or other computing devices. The terminal device may include, but is not limited to, a processor, a memory. Those skilled in the art will appreciate that the terminal device is not limited and may include more or fewer components than those shown, or some components may be combined, or different components, e.g., the terminal device may also include input output devices, network access devices, buses, etc.
The Processor may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The storage may be an internal storage unit of the terminal device, such as a hard disk or a memory of the terminal device. The memory may also be an external storage device of the terminal device, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like provided on the terminal device. Further, the memory may also include both an internal storage unit of the terminal device and an external storage device. The memory is used for storing computer programs and other programs and data required by the terminal device. The memory may also be used to temporarily store data that has been output or is to be output.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
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