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

Abstract

The present invention discloses a distribution network single-phase grounding fault identification method and system based on sudden change of electric energy information. The method uses the real-time electric energy information of the distribution network as basic data to construct an electric energy information matrix of the distribution network for single-phase grounding fault identification. The data can be directly obtained from the inherent acquisition device in the distribution network without the need to install other monitoring equipment, thereby eliminating the need to separately add basic line selection data acquisition equipment. The reliability of single-phase grounding fault identification will not be reduced due to the addition or failure of basic line selection data acquisition equipment. At the same time, the characteristic quantity of single-phase grounding fault is calculated and determined based on the electric energy information matrix of this scheme. The method is applicable to distribution networks of various structures, can better realize the integration of distribution systems and the complementary advantages, fully explore the distributed and multi-measurement point information of the existing monitoring and metering devices of the distribution network, and improve the accuracy of single-phase fault line selection.

Description

Technical Field

[0001] The present invention relates to the technical field of power system fault identification, and in particular to a single-phase grounding fault identification method and system based on multi-dimensional electric energy information fusion. Background Art

[0002] Distribution networks occupy a crucial position in the power system, serving as the end point of each link and providing direct access to users. They ensure stable power supply while also ensuring high-quality electricity for residents. However, due to the low voltage levels and lack of effective means for optimizing operation, distribution networks generally consume high power, presenting a significant potential bottleneck in the economic operation of the power system. According to fault analysis by power system operators, single-phase grounding is the most common fault in my country's urban and rural distribution networks, accounting for over 80% of electrical short-circuit faults, due to external factors such as birds, lightning, and wind. Distribution networks are widely distributed and operate in complex environments, resulting in a high probability of failure. Low-current grounding via arc suppression coils is widely used in distribution networks in China, continental Europe, Japan, and other countries. Ground fault detection and line selection protection in low-current grounded distribution networks are global challenges in the field of power system relay protection. The main difficulties include: 1) The boundaries of single-phase ground faults are complex and highly random, making them difficult to describe with a single unified model; 2) The steady-state component of the fault is small, making it difficult to construct passive detection and line selection criteria based on signal characteristics, making it difficult to reliably distinguish between transient faults, intermittent faults, and permanent faults, and resulting in blind protection outputs; 3) Due to the constraints of distribution network power supply reliability and power quality issues, the frequency and intensity of disturbances applied in active detection are severely limited, making it difficult to ensure sensitive detection of high-resistance faults and reliable protection selectivity.

[0003] Existing line selection methods for single-phase grounding faults are primarily categorized into three main categories: steady-state information-based fault line selection methods, transient information-based fault line selection methods, and multi-criteria fusion line selection methods based on line selection algorithms. Steady-state information-based fault line selection methods primarily include the zero-sequence current group amplitude and phase ratio method, the zero-sequence current amplitude method, the negative-sequence current method, the fifth harmonic method, the zero-sequence admittance method, and the residual increment method. Transient information-based fault line selection methods primarily include wavelet transform-based methods, the energy method, and the Hilbert-Huang transform-based method. Multi-criteria fusion line selection methods based on line selection algorithms primarily include neural network selection methods, DS evidence theory selection methods, and fuzzy theory selection methods. Different line selection equipment products have been developed and released based on different line selection methods. As power grids expand in size and complexity, devices that previously solved the problem of low-current grounding line selection are no longer applicable.

[0004] Based on the existing many single-phase grounding fault line selection methods, the main problems are: the existing single-phase grounding fault line selection methods are not fully compatible with distribution networks with various structures. Depending on the different distribution network structures, multiple fault line selection methods are used in a distribution network system. The failure to unify the fault line selection methods increases the manpower and material resources investment in the distribution network system, and the reliability of the fault line selection system cannot be guaranteed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the existing single-phase grounding fault line selection method cannot be fully matched and applied to distribution networks with various structures. According to the different distribution network structures, multiple fault line selection methods are used in one distribution network system. The fault line selection methods cannot be unified, which increases the manpower and material investment of 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 grounding fault identification method based on multi-dimensional information fusion of electric energy, and to construct an electric energy information matrix of the distribution network for single-phase grounding fault identification based on real-time electric energy information of the distribution network as basic data. There is no need to install other monitoring equipment, and the problem of reliability reduction caused by the increase of equipment will not be solved. At the same time, the electric energy information matrix of the present scheme is used to calculate and determine the characteristic quantity of the single-phase grounding fault, which is applicable to distribution networks with various structures and can better realize the integration of distribution systems and complementary advantages. The present invention also provides a single-phase grounding fault identification system based on multi-dimensional information fusion of electric energy to provide an equipment basis for the implementation of the method.

[0006] The present invention is achieved through the following technical solutions:

[0007] This solution provides a single-phase grounding fault identification method based on multi-dimensional power information fusion, including:

[0008] Step 1: Obtain real-time power information of the distribution network and construct the power information matrix of the distribution network;

[0009] Step 2: Based on the power information matrix, monitor whether the power at the distribution network bus end has a sudden change. When the power at the distribution network bus end has a sudden change, calculate the single-phase grounding fault characteristic quantity to determine whether it is a branch line single-phase grounding fault or a bus single-phase grounding fault;

[0010] Step 3: Compare the phase current amplitudes of the fault branch line or fault bus to select the single-phase grounding fault line.

[0011] Working principle of this scheme: The existing single-phase grounding fault line selection method cannot be fully matched and applied to distribution networks with various structures. Depending on the different distribution network structures, a distribution network system may use multiple fault line selection methods. The inability to unify the fault line selection methods increases the manpower and material resources investment in the distribution network system, and the reliability of the fault line selection system cannot be guaranteed; at the same time, since the traditional fault line selection method is not based on the common quantity monitored in the distribution network, such as the zero-sequence current group amplitude and phase ratio method and the zero-sequence current amplitude method, it is necessary to measure the zero-sequence current of each line in the distribution network, and there is a large inaccuracy in the measurement process. When the current of a phase in the line is affected and offset, although the measured zero-sequence current is correct, it will be impossible to accurately determine which single phase has failed when making the selection. The purpose of the present invention is to provide a single-phase grounding fault identification method and system based on the fusion of multi-dimensional electric energy information, which is suitable for single-phase grounding fault line selection in 10kV neutral-grounded and neutral-ungrounded distribution networks; the electric energy information matrix of the distribution network is constructed based on the real-time electric energy information of the distribution network to identify single-phase grounding faults. The representation of electric energy information is mainly current and voltage, and these two quantities are quantities that need to be monitored in real time in the distribution network; the current power consumption information collection system in the distribution network collects a large amount of data on the distribution network lines and users, and electric energy metering devices are also installed on the lines and user sides; when a single-phase grounding fault occurs, the voltage, current and electric energy signal performance on the electric energy metering device are Different, 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 directly obtained from the inherent acquisition device in the distribution network, without the need to install other monitoring equipment, eliminating the need to separately add basic line selection data acquisition equipment, and will not cause the reliability of single-phase grounding fault identification to decrease due to the increase or failure of basic line selection data acquisition equipment. At the same time, the single-phase grounding fault characteristic quantity is calculated and determined based on the electric energy information matrix of this scheme, which is suitable for distribution networks of various structures, can better realize the integration of distribution systems and complementary advantages, fully explore the distributed, multi-measurement point information of existing monitoring and metering devices in the distribution network, and improve the accuracy of single-phase fault line selection.

[0012] A further optimization solution is that the real-time power information of the distribution network includes: bus terminal voltage, bus current, voltage at the head end of each branch line, current at the head end of each branch line, voltage at the load end of each branch line, and current at the load end of each branch line.

[0013] 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;

[0014] The bus characteristic matrix N 总 Contains bus terminal voltage U 总 and bus current I 总 , N 总 =[I 总 U总 ];

[0015] The branch line characteristic matrix N 支 Contains the voltage U at the head end of each branch line n1 , the first end current I n1 , load terminal voltage U n2 and the load bus current I n2 ,

[0016] The power information matrix P of the distribution network system includes: bus power P 总 , branch line head end power P n1 and branch load power P n2 ,

[0017] A further optimization scheme is that step 2 includes the following sub-steps:

[0018] S21. Calculate the power fluctuation coefficient of each line;

[0019] S22. Extract the maximum value K of the power fluctuation coefficient of each branch within one cycle. i max , determine the maximum power jump coefficient K i max Is it greater than the preset coefficient threshold? If so, it is determined that the branch i is a single-phase grounding fault line; if the power jump coefficient K of all branches max If both are less than or equal to the preset coefficient threshold, it is determined to be a bus single-phase grounding fault.

[0020] A further optimization solution is that the line power fluctuation coefficient is calculated by the following formula:

[0021]

[0022] A further optimization solution is that the preset coefficient threshold is obtained based on simulation of a double-circuit distribution network system.

[0023] A further optimization solution is to preset the coefficient threshold to 20 for the neutral point grounded system and the neutral point ungrounded system of the double-circuit distribution network.

[0024] A further optimized solution is that step three specifically includes the following sub-steps:

[0025] S31: Obtain the three-phase current of the fault bus or fault branch within one cycle;

[0026] S32: Determine that the phase with the largest amplitude among the three-phase currents is the fault phase.

[0027] A further optimization solution is to further include step 4: outputting the fault bus line selection result or the fault branch line selection result.

[0028] The power fluctuation 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 the line and phase of the single-phase grounding fault line.

[0029] This solution also provides a single-phase grounding fault identification system based on multi-dimensional electric energy information fusion, which is applied to the above method and includes: an acquisition and analysis module, a single-phase grounding fault characteristic quantity calculation and analysis module, and a line selection module;

[0030] The acquisition and analysis module is used to obtain real-time power information of the distribution network and construct the power information matrix of the distribution network;

[0031] The single-phase grounding fault characteristic quantity calculation and analysis is based on the power information matrix monitoring whether the power of the distribution network bus end has a sudden change. When the power of the distribution network bus end has a sudden change, the single-phase grounding fault characteristic quantity calculation is performed to determine whether it is a branch line single-phase grounding fault or a bus single-phase grounding fault;

[0032] The line selection module is used to compare the phase current amplitudes of the fault branch line or the fault bus to realize single-phase grounding fault line selection.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] The single-phase grounding fault identification method and system based on multi-dimensional electric energy information fusion provided by the present invention uses the real-time electric energy information of the distribution network as basic data to construct an electric energy information matrix of the distribution network for single-phase grounding fault identification. The information can be directly obtained from the inherent collection device in the distribution network without the need to install other monitoring equipment, eliminating the need to separately add basic line selection data collection equipment. The reliability of single-phase grounding fault identification will not be reduced due to the addition or failure of basic line selection data collection equipment. At the same time, the single-phase grounding fault characteristic quantity is calculated and determined based on the electric energy information matrix of this scheme. It is suitable for distribution networks of various structures, can better realize the integration of distribution systems and complementary advantages, fully explore the distributed and multi-measurement point information of the existing monitoring and metering devices in the distribution network, and improve the accuracy of single-phase fault line selection. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings:

[0036] Figure 1 The figure is a flow chart of a single-phase grounding fault identification method based on multi-dimensional electric energy information fusion;

[0037] Figure 2 is a schematic diagram of the bus current waveform;

[0038] Figure 3 Schematic diagram of the current waveform at the head end of branch line 1;

[0039] Figure 4 Schematic diagram of the load-end current waveform of branch line 1;

[0040] Figure 5 Schematic diagram of the current waveform at the head end of branch line 2;

[0041] Figure 6 Schematic diagram of the load-end current waveform of branch line 2;

[0042] Figure 7 is a schematic diagram of the bus voltage waveform;

[0043] Figure 8 Schematic diagram of voltage waveform at the head end of branch line 1;

[0044] Figure 9 Schematic diagram of voltage waveform at the load end of branch line 1;

[0045] Figure 10 Schematic diagram of voltage waveform at the head end of branch line 2;

[0046] Figure 11 Schematic diagram of voltage waveform at the load end of branch line 2;

[0047] Figure 12 Schematic diagram of bus power waveform;

[0048] Figure 13 This is a schematic diagram of the power waveform at the head end of branch line 1;

[0049] Figure 14 Schematic diagram of power waveform at the load end of branch line 1;

[0050] Figure 15 This is a schematic diagram of the power waveform at the head end of branch line 2;

[0051] Figure 16 Schematic diagram of the power waveform at the load end of branch line 2. DETAILED DESCRIPTION

[0052] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0053] Example 1

[0054] This embodiment provides a single-phase grounding fault identification method based on multi-dimensional power information fusion, such as Figure 1 As shown, the steps include:

[0055] Step 1: Obtain real-time power information of the distribution network and construct the power information matrix of the distribution network;

[0056] Step 2: Based on the power information matrix, monitor whether the power at the distribution network bus end has a sudden change. When the power at the distribution network bus end has a sudden change, calculate the single-phase grounding fault characteristic quantity to determine whether it is a branch line single-phase grounding fault or a bus single-phase grounding fault;

[0057] Step 3: Compare the phase current amplitudes of the fault branch line or fault bus to select the single-phase grounding fault line.

[0058] The real-time electric energy information obtained from the distribution network includes: bus terminal voltage, bus current, voltage at the head end of each branch line, current at the head end of each branch line, voltage at the load end of each branch line, and current at the load end of each branch line.

[0059] The electric energy information matrix includes: a bus characteristic matrix, a branch characteristic matrix and a distribution network system power information matrix;

[0060] The bus characteristic matrix N 总 Contains bus terminal voltage U 总 and bus current I 总 , N 总 =[I 总 U 总 ](1);

[0061] The branch line characteristic matrix N 支 Contains the voltage U at the head end of each branch line n1 , the first end current I n1 , load terminal voltage U n2 and the load bus current I n2 ,

[0062] The power information matrix P of the distribution network system includes: bus power P 总 , branch line head end power P n1 and branch load power P n2 ,

[0063] Step 2 includes the following sub-steps:

[0064] S21. Calculate the power fluctuation coefficient of each line;

[0065] S22. Extract the maximum value K of the power fluctuation coefficient of each branch within one cycle. imax , determine the maximum power jump coefficient K i max Is it greater than the preset coefficient threshold? If so, it is determined that the branch i is a single-phase grounding fault line; if the power jump coefficient K of all branches max If both are less than or equal to the preset coefficient threshold, it is determined to be a bus single-phase grounding fault.

[0066] The line power fluctuation coefficient is calculated by the following formula:

[0067]

[0068] K i max =[k i1 k i2 L k in ] max (5).

[0069] The preset coefficient threshold is obtained based on simulation of a double-circuit distribution network system.

[0070] For double-circuit distribution networks with grounded neutral points and ungrounded neutral points, the preset coefficient threshold is 20.

[0071] The step three specifically includes the following sub-steps:

[0072] S31: Obtain the three-phase current of the fault bus or fault branch within one cycle;

[0073] S32: Determine the phase with the largest amplitude among the three-phase currents as the fault phase; 故障 =[I A I B I C ] max (6)

[0074] The method further includes step 4: outputting a fault bus line selection result or a fault branch line selection result.

[0075] This solution calculates the power fluctuation coefficients of different lines and detects the amplitude of the fault phase current to complete the line and phase selection function for single-phase grounding faults. By analyzing the changes in power information at multiple nodes, the power fluctuation coefficient of each node is calculated to determine the single-phase grounding fault line. The amplitudes of the three-phase currents of the fault line are further compared to determine the single-phase grounding fault phase, ultimately achieving the identification of the single-phase grounding fault. This patent has the advantages of high reliability, low cost, a high signal-to-noise ratio of the line selection characteristic quantity, and strong anti-interference ability. It further improves the accuracy of line and phase selection for single-phase grounding faults and ensures the safe and stable operation of the distribution network.

[0076] Example 2

[0077] This embodiment provides a single-phase grounding fault identification system based on multi-dimensional electric energy information fusion, which is applied to the method described in the previous embodiment and includes: an acquisition and analysis module, a single-phase grounding fault characteristic quantity calculation and analysis module, and a line selection module;

[0078] The acquisition and analysis module is used to obtain real-time power information of the distribution network and construct the power information matrix of the distribution network;

[0079] The single-phase grounding fault characteristic quantity calculation and analysis is based on the power information matrix monitoring whether the power of the distribution network bus end has a sudden change. When the power of the distribution network bus end has a sudden change, the single-phase grounding fault characteristic quantity calculation is performed to determine whether it is a branch line single-phase grounding fault or a bus single-phase grounding fault;

[0080] The line selection module is used to compare the phase current amplitudes of the fault branch line or the fault bus to realize single-phase grounding fault line selection.

[0081] Example 3

[0082] This embodiment is based on the method or system of the above embodiment to identify a single-phase grounding fault in a double-circuit distribution network system. The voltage and current monitoring information on the bus, branch line 1 and branch line 2 of the 10kV double-circuit distribution network in the distribution network system is as follows: Figure 2-11 As shown, the power information of the bus, branch 1 and branch 2 is calculated as follows Figure 12-16 shown.

[0083] At 0.1s, the bus characteristic matrix N 总1 As shown in formula (7), at 0.115s, the bus characteristic matrix N 总2 , as shown in formula (8).

[0084] N 总1 =[(-1.833,-3.696,5.340) (4337,-8279,3942)] (7)

[0085] N 总2 =[(-58.66,2.412,3.580) (-5886,690.8,8204)] (8)

[0086] According to calculations, the bus power at 0.1s is 43690W, and at 0.115s is 376300W. The bus power increases by about 9 times, and the bus power undergoes a sudden change.

[0087] Construct the branch line characteristic matrix N at 0.115s 支 , as shown in formula (9).

[0088]

[0089] According to the branch characteristic matrix N 支 The power information matrix P is calculated as shown in formula (10), and the power jump coefficient k of each line is calculated by combining formula (4): n As shown in formulas (11) and (12), combined with formula (5), the maximum value of the power jump coefficient of each line is k1, and k1 is greater than 20. Therefore, the result obtained according to the data is that a single-phase grounding fault occurs in branch 1.

[0090]

[0091]

[0092]

[0093] Formula (6) is used to compare the three-phase current amplitudes of branch 1, as shown in Formula 13. According to the result, it can be seen that the phase where the single-phase grounding fault occurs in the fault line is phase A, and the final output result is: a single-phase grounding fault occurs in phase A of branch 1.

[0094] I 故障 =[63.93 3.295 3.565] max =63.93 (13)

[0095] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A single-phase grounding fault identification method based on multi-dimensional electric energy information fusion is characterized by: include: Step 1: Obtain real-time power information of the distribution network and construct the power information matrix of the distribution network; The real-time power information of the distribution network includes: bus terminal voltage, bus current, voltage at the head end of each branch line, current at the head end of each branch line, voltage at the load end of each branch line, and current at the load end of each branch line; 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 总 Contains bus terminal voltage U 总 and bus current I 总 , N 总 =[I 总 U 总 ]; The branch line characteristic matrix N 支 Contains the voltage U at the head end of each branch line n1 , the first end current I n1 , load terminal voltage U n2 and the load current I n2 , The power information matrix P of the distribution network system includes: bus power P 总 , power P at the head end of the branch line n1 And the branch load power P n2 , Step 2: Based on the power information matrix, monitor whether the power at the distribution network bus end has a sudden change. When the power at the distribution network bus end has a sudden change, calculate the single-phase grounding fault characteristic quantity to determine whether it is a branch line single-phase grounding fault or a bus single-phase grounding fault. Step 2 includes the following sub-steps: S21. Calculate the power fluctuation coefficient of each line. The power fluctuation coefficient of each line is calculated by the following formula: S22. Extract the maximum value K of the power fluctuation coefficient of each branch within one cycle. i max , determine the maximum power jump coefficient K i max Is it greater than the preset coefficient threshold? If so, it is determined that the branch i is a single-phase grounding fault line; if the power jump coefficient K of all branches max If both are less than or equal to the preset coefficient threshold, it is determined to be a bus single-phase grounding fault; Step 3: Compare the phase current amplitudes of the fault branch line or the fault bus to select the single-phase grounding fault line; Step 3 specifically includes the following sub-steps: S31: Obtain the three-phase current of the fault bus or fault branch within one cycle; S32: Determine that the phase with the largest amplitude among the three-phase currents is the fault phase.

2. The single-phase grounding fault identification method based on electric energy multi-dimensional information fusion according to claim 1 is characterized in that: The preset coefficient threshold is obtained based on simulation of a double-circuit distribution network system.

3. The single-phase grounding fault identification method based on electric energy multi-dimensional information fusion according to claim 1 is characterized in that: For double-circuit distribution networks with grounded neutral points and ungrounded neutral points, the preset coefficient threshold is 20.

4. The single-phase grounding fault identification method based on electric energy multi-dimensional information fusion according to claim 1 is characterized in that: The method further includes step 4: outputting a fault bus line selection result or a fault branch line selection result.

5. A single-phase ground fault identification system based on multi-dimensional electric energy information fusion, applied to the method according to any one of claims 1 to 4, characterized in that: include: Acquisition and analysis module, single-phase grounding fault characteristic quantity calculation and analysis module and line selection module; The acquisition and analysis module is used to obtain real-time power information of the distribution network and construct the power information matrix of the distribution network; The single-phase grounding fault characteristic quantity calculation and analysis is based on the power information matrix monitoring whether the power of the distribution network bus end has a sudden change. When the power of the distribution network bus end has a sudden change, the single-phase grounding fault characteristic quantity calculation is performed to determine whether it is a branch line single-phase grounding fault or a bus single-phase grounding fault; The line selection module is used to compare the phase current amplitudes of the fault branch line or the fault bus to realize single-phase grounding fault line selection.

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