WO2023206897A1

WO2023206897A1 - Method and system for identifying single-phase grounding fault on the basis of multi-dimensional electric-energy information fusion

Info

Publication number: WO2023206897A1
Application number: PCT/CN2022/116292
Authority: WO
Inventors: 汪佳; 周一飞; 刘刚; 严平; 程志炯; 黄嘉鹏; 张杰夫; 李金嵩; 叶子阳; 蔡君懿
Original assignee: 国网四川省电力公司营销服务中心
Priority date: 2022-04-26
Filing date: 2022-08-31
Publication date: 2023-11-02
Also published as: CN114755532A

Abstract

A method and system for identifying a single-phase grounding fault of a power distribution network on the basis of electric-energy information mutation. An electric-energy information matrix of a power distribution network is constructed by taking real-time electric-energy information of the power distribution network as basic data, so as to identify a single-phase grounding fault. The electric-energy information matrix can be directly acquired from an inherent collection apparatus of the power distribution network, without the need to mount other monitoring devices, thereby omitting an additional line-selection basic data collection device, which is individually provided, and preventing the problem of the reliability of identifying a single-phase grounding fault being reduced due to a line-selection basic data collection device being added or being faulty. Moreover, the characteristic quantity of a single-phase grounding fault is calculated and determined according to the electric-energy information matrix; the method and system are suitable for power distribution networks of various structures; the fusion and mutual advantages of marketing and power distribution systems can be better realized; distributed and multi-measurement-point information of existing monitoring and metering apparatuses of a power distribution network are fully explored; and the accuracy of single-phase fault line selection is improved.

Description

Single-phase ground fault identification method and system based on multi-dimensional information fusion of electric energy

Technical field

The present invention relates to the technical field of power system fault identification, and specifically relates to a single-phase ground fault identification method and system based on multi-dimensional information fusion of electric energy.

Background technique

The distribution network occupies an important position in the power system. As the end of each link, it directly contacts users; on the one hand, it ensures the provision of stable electric energy and at the same time ensures that residents can use high-quality electric energy. Due to the low voltage level of the distribution network, there is a lack of An effective means to optimize operation, the power consumption is generally high, and it is a potential user for the economic operation of the power system. According to the analysis of faults by the power system operation department, due to the influence of external factors (such as birds, lightning, wind, etc.), the highest proportion of faults in my country's urban and rural distribution network systems is single-phase grounding, accounting for more than 80% of electrical short-circuit faults. The distribution network has a wide distribution range, complex operating environment, and a high probability of fault occurrence. The distribution network in China, continental Europe, Japan and other countries widely adopts the small current grounding method through arc suppression coils. Ground fault detection and line selection protection in small current grounded distribution networks are global problems in the field of power system relay protection. The main difficulties include: 1) Single-phase ground fault boundaries are complex and highly random, making it difficult to describe with a single unified model; 2 ) The steady-state component of the fault is small, it is difficult to construct passive detection and line selection criteria based on signal characteristics, it is difficult to reliably distinguish transient faults, intermittent faults and permanent faults, and the protection outlet is blind; 3) It is affected by the reliability of the power supply of the distribution network and Constrained by power quality issues, the frequency and intensity of disturbances in active detection are severely limited, making it difficult to ensure the selectivity of sensitive detection and reliable protection of high-resistance faults.

For single-phase ground fault line selection, existing line selection methods are mainly divided into three categories: fault line selection methods based on steady-state information, fault line selection methods based on transient information, and multi-criteria fusion selection methods based on line selection algorithms. Line method; among them, fault line selection methods based on steady-state information mainly include: zero-sequence current group ratio amplitude ratio method, zero-sequence current amplitude method, negative sequence current method, fifth harmonic method, zero-sequence admittance method, Residual incremental method; fault line selection methods based on transient information mainly include: wavelet transform-based methods, energy methods, and Hilbert-huang transform-based methods; multi-criteria fusion line selection methods based on line selection algorithms mainly include: neural Network line selection method, D-S evidence theory line selection method, fuzzy theory line selection method. Different line selection equipment products have been developed and launched based on different line selection methods; with the expansion of the scale of the power grid, the complexity of the power grid is getting higher and higher, and the devices that could solve the problem of small current grounding line selection in the past are no longer applicable.

Based on the many existing single-phase ground fault line selection methods, the main problems are: the existing single-phase ground fault line selection methods cannot be fully matched and applicable to distribution networks with various structures. Depending on the structure of the distribution network, one A variety of fault line selection methods are used in the distribution network system. The fault line selection methods cannot be unified, which increases the investment of manpower and material resources in the distribution network system, and the reliability of the fault line selection system cannot be guaranteed.

Contents of the invention

The technical problem to be solved by this invention is that the existing single-phase ground fault line selection method cannot be fully matched and applicable to distribution networks with various structures. According to the different structures of the distribution network, multiple faults are used in one distribution network system. Line selection methods and fault line selection methods cannot be unified, which increases the investment of manpower and material resources in the distribution network system, and the reliability of the fault line selection system cannot be guaranteed; the purpose of the present invention is to provide a single-phase ground fault identification method based on multi-dimensional information fusion of electric energy , based on the real-time power information of the distribution network, the power information matrix of the distribution network is constructed to identify single-phase ground faults. There is no need to install other monitoring equipment, and there will be no problem of reduced reliability due to the increase in equipment. At the same time, according to this solution The electric energy information matrix calculates and determines single-phase ground fault characteristic quantities, is suitable for distribution networks with various structures, and can better realize the integration and complementation of advantages of the distribution system; the present invention also provides single-phase ground fault based on multi-dimensional information fusion of electric energy. The identification system provides the equipment basis for the implementation of the method.

The present invention is realized through the following technical solutions:

This solution provides a single-phase ground fault identification method based on multi-dimensional information fusion of electric energy, including:

Step 1: Obtain real-time power information of the distribution network and construct the power information matrix of the distribution network;

Step 2: Based on the power information matrix, monitor whether the power at the bus end of the distribution network mutates. When the power at the bus end of the distribution network mutates, calculate the single-phase ground fault characteristic quantity to determine whether it is a branch line single-phase ground fault or a bus single-phase ground fault. ;

Step 3: Compare the phase current amplitudes of the faulty branch line or fault bus to achieve single-phase ground fault line selection.

Working principle of this scheme: The existing single-phase ground fault line selection method cannot be fully matched and applicable to distribution networks with various structures. Depending on the structure of the distribution network, a distribution network system may use multiple fault line selection methods. The fault line selection method cannot be unified, which increases the investment of manpower and material resources in the distribution network system, and the reliability of the fault line selection system cannot be guaranteed; at the same time, because the traditional fault line selection method is based on the quantity that has been monitored in the distribution network. Common quantities, such as the zero-sequence current group ratio amplitude ratio method and the zero-sequence current amplitude method, which need to measure the zero-sequence current of each line in the distribution network, have great inaccuracies in the measurement process. When a certain phase current in the line is affected and offset, although the measured zero sequence current is correct, when making options, it will be difficult to accurately determine which single phase has failed. The purpose of this invention is to provide a single-phase ground fault identification method and system based on multi-dimensional information fusion of electric energy, which is suitable for single-phase ground fault line selection of 10kV neutral point grounded and neutral point ungrounded distribution networks; with real-time analysis of distribution network The electric energy information is used as the basic data to construct the electric energy information matrix of the distribution network to identify single-phase ground faults. The representation of electric energy information is mainly current and voltage, and these two quantities need to be monitored in real time in the distribution network. At present, the distribution network The electricity consumption information collection system in China collects a large amount of data on distribution network lines and users, and electric energy metering devices are also installed on the lines and user sides; when a single-phase ground fault occurs, the voltage, current and power on the electric energy metering device Energy signals behave differently. A large amount of electric energy information data can be easily extracted from the acquisition system. Therefore, at the basic data level, it can be obtained directly from the inherent acquisition device in the distribution network. There is no need to install other monitoring equipment, and there is no need to add separate line selections. Basic data acquisition equipment will not cause the problem of reduced reliability of single-phase ground fault identification due to the increase or failure of basic data acquisition equipment for line selection. At the same time, single-phase ground fault characteristic quantities are calculated and determined based on the power information matrix of this solution, which is suitable for Distribution networks with multiple structures can better realize the integration and complementation of advantages of the distribution network, fully explore the distributed and multi-measurement point information of existing monitoring and metering devices in the distribution network, and improve the accuracy of single-phase fault line selection.

A further optimization solution is that the real-time power information of the distribution network includes: bus terminal voltage, bus current, each branch line head end voltage, each branch line head end current, each branch line load end voltage and each branch line load end current.

A further optimization solution is that the electric energy information matrix includes: a bus characteristic matrix, a branch characteristic matrix and a distribution network system power information matrix;

The bus characteristic matrix N _total includes bus terminal voltage U _{total and} bus current I _total , N _total = [I _total U _total ];

The N _branches of the branch line characteristic matrix include the head-end voltage U _n1 , the head-end current I _n1 , the load-side voltage U _n2 and the load-side bus current I _n2 of each branch.

The distribution network system power information matrix P includes: bus power P _total , branch line head end power P _n1 and branch line load end power P _n2 ,

The further optimization plan is that step 2 includes the following sub-steps:

S21. Calculate the power jitter coefficient of each line;

S22. Within one cycle, extract the maximum value K ⁱ _max among the power bounce coefficients of each branch line, and determine whether the maximum power bounce coefficient K ⁱ _max is greater than the preset coefficient threshold; if so, determine the single-phase ground fault line of branch line i; if If the power bounce coefficient K _max of all branches is less than or equal to the preset coefficient threshold, it is determined to be a bus single-phase ground fault.

A further optimization solution is that the line power bounce coefficient is calculated by the following formula:

A further optimization solution is that the preset coefficient threshold is obtained based on simulation of a double-circuit distribution network system.

A further optimization plan is that for the neutral point grounded system and the neutral point ungrounded system of the double-circuit distribution network, the preset coefficient threshold is 20.

A further optimization solution is that step three specifically includes the following sub-steps:

S31: Obtain the three-phase current of the fault bus or fault branch in one cycle;

S32: Determine the phase with the largest amplitude among the three-phase currents as the fault phase.

The further optimization plan also includes step four: outputting the faulty bus line selection result or the faulty branch line selection result.

The power bounce coefficient and fault phase current amplitude in this scheme have the advantages of high signal-to-noise ratio and strong anti-interference ability, and can accurately select lines and phases for single-phase ground fault lines.

This solution also provides a single-phase ground fault identification system based on multi-dimensional information fusion of electric energy, applied to the above method, including: acquisition analysis module, single-phase ground fault characteristic quantity calculation and analysis module and line selection module;

The collection and analysis module is used to obtain real-time electric energy information of the distribution network and construct an electric energy information matrix of the distribution network;

The calculation and analysis of the single-phase ground fault characteristic quantity is based on the power information matrix to monitor whether the power at the bus end of the distribution network mutates. When the power at the bus end of the distribution network mutates, the single-phase ground fault characteristic quantity is calculated to determine whether the branch line is single-phase grounded. Fault or bus single-phase ground fault;

The line selection module is used to compare phase current amplitudes of faulty branches or fault buses to achieve single-phase ground fault line selection.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The single-phase ground fault identification method and system based on the multi-dimensional information fusion of electric energy provided by the present invention uses the real-time electric energy information of the distribution network as the basic data to construct the electric energy information matrix of the distribution network for single-phase ground fault identification, which can be directly obtained from the distribution network. Obtained from the inherent acquisition device in the network, there is no need to install other monitoring equipment, and there is no need to add separate basic data collection equipment for line selection. The reliability of single-phase ground fault identification will not be reduced due to the increase or failure of basic data collection equipment for line selection. problem, and at the same time, the single-phase ground fault characteristic quantity is calculated and determined based on the power information matrix of this solution. It is suitable for distribution networks with various structures. It can better realize the integration and complementation of advantages of the distribution network, and fully explore the existing monitoring systems of the distribution network. , distributed and multi-measurement point information of metering devices to improve the accuracy of line selection for single-phase faults.

Description of drawings

In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention. Therefore, it should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without exerting creative efforts. In the attached picture:

Figure 1 is a schematic flow chart of the single-phase ground fault identification method based on multi-dimensional information fusion of electric energy;

Figure 2 is a schematic diagram of the current waveform of the bus;

Figure 3 is a schematic diagram of the current waveform at the head end of branch line 1;

Figure 4 is a schematic diagram of the load end current waveform of branch line 1;

Figure 5 is a schematic diagram of the current waveform at the head end of branch line 2;

Figure 6 is a schematic diagram of the load end current waveform of branch line 2;

Figure 7 is a schematic diagram of the voltage waveform of the bus;

Figure 8 is a schematic diagram of the voltage waveform at the head end of branch line 1;

Figure 9 is a schematic diagram of the load end voltage waveform of branch line 1;

Figure 10 is a schematic diagram of the voltage waveform at the head end of branch line 2;

Figure 11 is a schematic diagram of the load end voltage waveform of branch line 2;

Figure 12 is a schematic diagram of the power waveform of the bus;

Figure 13 is a schematic diagram of the power waveform at the head end of branch line 1;

Figure 14 is a schematic diagram of the load end power waveform of branch line 1;

Figure 15 is a schematic diagram of the power waveform at the head end of branch line 2;

Figure 16 is a schematic diagram of the load end power waveform of branch line 2.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the examples and drawings. The schematic embodiments of the present invention and their descriptions are only used to explain the present invention and do not as a limitation of the invention.

Example 1

This embodiment provides a single-phase ground fault identification method based on multi-dimensional information fusion of electric energy, as shown in Figure 1, including the steps:

The real-time power information obtained from the distribution network includes: bus terminal voltage, bus current, head-end voltage of each branch line, head-end current of each branch line, load-end voltage of each branch line, and load-end current of each branch line.

The electric energy information matrix includes: bus characteristic matrix, branch characteristic matrix and distribution network system power information matrix;

The bus characteristic matrix N _total includes bus terminal voltage U _{total and} bus current I _total , N _total = [I _total U _total ] (1);

Step two includes the following sub-steps:

S21. Calculate the power jitter coefficient of each line;

The line power bounce coefficient is calculated by the following formula:

K ⁱ _max =[k _i1 k _i2 L k _in ] _max (5).

The preset coefficient threshold is obtained based on simulation of a double-circuit distribution network system.

For the neutral point grounded system and the neutral point ungrounded system of the double-circuit distribution network, the preset coefficient threshold is 20.

The third step specifically includes the following sub-steps:

S32: Determine the phase with the largest amplitude among the three-phase current as the fault phase; I _fault = [I _A I _B I _C ] _max (6)

It also includes step four: outputting the faulty bus line selection result or the faulty branch line selection result.

Based on the calculation of the power bounce coefficient of different lines and the detection of fault phase current amplitude, this solution completes the line and phase selection function for single-phase ground faults. By analyzing the changes in multi-node power information, the power bounce coefficient of each node is calculated, and the single-phase grounding fault is determined. Phase-to-ground fault line; further compare the amplitudes of the three-phase currents of the fault line to determine the single-phase to ground fault phase, and finally realize the identification of single-phase to ground fault. This patent has the advantages of high reliability, low cost, large signal-to-noise ratio of line selection characteristics, and strong anti-interference ability. It further improves the accuracy of line and phase selection for single-phase ground faults and ensures the safe and stable operation of the distribution network.

Example 2

This embodiment provides a single-phase ground fault identification system based on multi-dimensional information fusion of electric energy, applied to the method described in the previous embodiment, including: a collection analysis module, a single-phase ground fault characteristic quantity calculation and analysis module, and a line selection module;

Example 3

This embodiment uses the method or system of the above embodiment to identify single-phase ground faults in a certain double-circuit distribution network system. In the distribution network system, the bus, branch line 1 and branch line 2 of the 10kV double-circuit distribution network are The voltage and current monitoring information are shown in Figure 2-11. The calculated power information of the bus, branch line 1 and branch line 2 is shown in Figures 12 to 16.

At 0.1s, the bus characteristic matrix N _{is always 1} , as shown in equation (7). At 0.115s, the bus characteristic matrix N _{is always 2} , as shown in equation (8).

N _{total 1} =[(-1.833,-3.696,5.340)(4337,-8279,3942)] (7)

N _{total 2} =[(-58.66,2.412,3.580)(-5886,690.8,8204)] (8)

According to calculations, the bus power at 0.1s is 43690W, and at 0.115s the bus power is 376300W. The bus power increases by about 9 times, and the bus power changes suddenly.

Construct branch line characteristic matrix N _branches at 0.115s time, as shown in Equation (9).

The power information _matrix P is calculated according to the branch line characteristic matrix N, as shown in equation (10). Combined with equation (4), the power jump coefficient k _n of each line is calculated as shown in equations (11) and (12). Combined with equation (4) 5) The maximum value of the power bounce coefficient of each line is calculated to be k ₁ , and k ₁ is greater than 20, so the result based on the data is that a single-phase ground fault occurred in branch 1.

Use formula (6) to compare the three-phase current amplitudes of branch 1, as shown in formula 13. According to the results, it can be seen that the single-phase ground fault in the fault line is phase A, and the final output result is: branch 1 has A. Single phase to ground fault.

I _failure = [63.93 3.295 3.565] _max = 63.93 (13)

The above-described specific embodiments further describe the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above-mentioned are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

The single-phase ground fault identification method based on multi-dimensional information fusion of electric energy is characterized by:

Step 1: Obtain real-time power information of the distribution network and construct the power information matrix of the distribution network;

Step 2: Based on the power information matrix, monitor whether the power at the bus end of the distribution network mutates. When the power at the bus end of the distribution network mutates, calculate the single-phase ground fault characteristic quantity to determine whether it is a branch line single-phase ground fault or a bus single-phase ground fault. ;

Step 3: Compare the phase current amplitudes of the faulty branch line or fault bus to achieve single-phase ground fault line selection.
The single-phase ground fault identification method based on multi-dimensional information fusion of electric energy according to claim 1, characterized in that:

The real-time power information obtained from the distribution network includes: bus terminal voltage, bus current, head-end voltage of each branch line, head-end current of each branch line, load-end voltage of each branch line, and load-end current of each branch line.
The single-phase ground fault identification method based on multi-dimensional information fusion of electric energy according to claim 2, characterized in that the electric energy information matrix includes: a bus characteristic matrix, a branch characteristic matrix and a distribution network system power information matrix;

The bus characteristic matrix N total includes bus terminal voltage U total and bus current I total , N total = [I total U total ];

The N branches of the branch line characteristic matrix include the head-end voltage U n1 , head-end current I n1 , load-end voltage U n2 and load-end current I n2 of each branch line,

The distribution network system power information matrix P includes: bus power P total , branch line head end power P n1 and branch line load end power P n2 ,
The single-phase ground fault identification method based on multi-dimensional information fusion of electric energy according to claim 3, characterized in that step two includes the following sub-steps:

S21. Calculate the power jitter coefficient of each line;

S22. Within one cycle, extract the maximum value K i max among the power bounce coefficients of each branch line, and determine whether the maximum power bounce coefficient K i max is greater than the preset coefficient threshold; if so, determine the single-phase ground fault line of branch line i; if If the power bounce coefficient K max of all branches is less than or equal to the preset coefficient threshold, it is determined to be a bus single-phase ground fault.
The single-phase ground fault identification method based on multi-dimensional information fusion of electric energy according to claim 4, characterized in that the line power bounce coefficient is calculated by the following formula:
The single-phase ground fault identification method based on multi-dimensional information fusion of electric energy according to claim 4, characterized in that the preset coefficient threshold is obtained based on simulation of a double-circuit distribution network system.
The single-phase ground fault identification method based on multi-dimensional information fusion of electric energy according to claim 1, characterized in that, for the neutral point grounded system and the neutral point ungrounded system of the double-circuit distribution network, the preset coefficient threshold is 20.
The single-phase ground fault identification method based on multi-dimensional information fusion of electric energy according to claim 1, characterized in that said step three specifically includes the following sub-steps:

S31: Obtain the three-phase current of the fault bus or fault branch in one cycle;

S32: It is determined that the phase with the largest amplitude among the three-phase current is the fault phase.
The single-phase ground fault identification method based on multi-dimensional information fusion of electric energy according to claim 1, further comprising step 4: outputting the fault bus line selection result or the fault branch line selection result.
The single-phase ground fault identification system based on multi-dimensional information fusion of electric energy is applied to the method described in any one of claims 1 to 9, which is characterized in that it includes: an acquisition analysis module, a single-phase ground fault characteristic quantity calculation and analysis module and a line selection module. module;

The collection and analysis module is used to obtain real-time electric energy information of the distribution network and construct an electric energy information matrix of the distribution network;

The calculation and analysis of the single-phase ground fault characteristic quantity is based on the power information matrix to monitor whether the power at the bus end of the distribution network mutates. When the power at the bus end of the distribution network mutates, the single-phase ground fault characteristic quantity is calculated to determine whether the branch line is single-phase grounded. Fault or bus single-phase ground fault;

The line selection module is used to compare phase current amplitudes of faulty branch lines or fault buses to achieve single-phase ground fault line selection.