New energy station sending line pilot protection method and system based on hamming distance

Abstract

The application belongs to the technical field of new energy sending-out line protection, and provides a new energy station sending-out line pilot protection method and system based on Hamming distance. The new energy station sending-out line pilot protection method comprises obtaining current sampling values of the station side and the system side of the sending-out line after protection starting; data preprocessing is performed on the current sampling values of the station side and the system side of the sending-out line, and a first numerical sequence and a second numerical sequence containing 0 and 1 are obtained respectively; the Hamming distance is calculated according to the ratio of the different sampling point numbers between the first numerical sequence and the second numerical sequence to the sampling point number of the sampling window length; the fault type is judged according to the size of the Hamming distance, and whether to issue a trip command to the protection devices of the station side and the system side of the sending-out line is judged in combination with the comparison result of the Hamming distance and the setting value of the Hamming distance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of new energy sending-out line protection, and particularly relates to a new energy station sending-out line pilot protection method and system based on Hamming distance. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] In recent years, wind power, photovoltaic power stations and other new energy stations have developed rapidly. For the establishment of large-scale new energy stations, 35kV lines are often used for collection, and 35 / 220kV step-up is used for centralized grid connection. For high-proportion power electronic systems connected with new energy, protection refusal during fault may cause large-scale disconnection of multiple new energy stations, resulting in serious economic and safety problems. In order to ensure the safety of high-proportion new energy grid connection, the power grid relay protection needs to be reliable and fast to remove faults, so it is of great significance to study the protection of new energy station sending-out line.

[0004] Due to the need for power electronic connection of new energy stations, in order to avoid overcurrent, the fault characteristics of new energy power sources are affected by control strategies during fault, and the short-circuit current presents the characteristics of limited amplitude, controlled phase angle and existence of non-power frequency quantities, which is quite different from the fault characteristics of synchronous machines. For traditional protection, the protection principle is mainly aimed at power frequency quantities. For new energy fault characteristics containing non-power frequency quantities, the action performance of traditional protection decreases, and even there is a risk of refusal. SUMMARY

[0005] In order to solve the technical problems in the background art, the present application provides a new energy station sending-out line pilot protection method and system based on Hamming distance, which is constructed according to the fault characteristics of new energy power sources and is suitable for new energy sending-out line protection.

[0006] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0007] The first aspect of the present application provides a new energy station sending-out line pilot protection method based on Hamming distance.

[0008] A new energy station sending-out line pilot protection method based on Hamming distance, comprising:

[0009] Obtaining the current sampling values of the station side and the system side of the sending-out line after protection starting;

[0010] Data preprocessing is performed on the current sampling values of the station side and the system side of the sending-out line to obtain a first numerical sequence and a second numerical sequence containing 0 and 1, respectively;

[0011] The Hamming distance is calculated based on the ratio of the number of different sampling points between the first and second numerical sequences to the number of sampling points in the sampling window.

[0012] The fault type is determined based on the magnitude of the Hamming distance. Then, by comparing the Hamming distance with the set value of the Hamming distance, it is determined whether to issue a trip command to the protection devices on the station side and system side of the sending line.

[0013] As one implementation method, in the process of determining the fault type based on the magnitude of the Hamming distance:

[0014] When the Hamming distance is 0, it is determined to be an out-of-area fault;

[0015] When the Hamming distance is greater than 0, it is determined to be an intra-zone fault.

[0016] As one implementation method, when a fault is determined to be within the zone and the Hamming distance is greater than the set value of the Hamming distance, a trip command is issued to the protection devices on the station side and the system side of the sending line, respectively.

[0017] As one implementation, the Hamming distance is set to the product of the phase angle error caused by CT transmission and distributed capacitance and the margin coefficient that retains the set margin.

[0018] As one implementation method, the process of preprocessing the current sampling values ​​on the station side and system side of the transmitting line includes:

[0019] For either the station side or the system side of the transmitting line, first take the negative value of the current on the opposite side, then calculate the average value of the current sampling value. When the current signal sampling value is greater than or equal to the average value, the corresponding current signal sampling value is set to 1; when the current signal sampling value is less than the average value, the corresponding current signal sampling value is set to 0.

[0020] A second aspect of the present invention provides a longitudinal protection system for power transmission lines of new energy power plants based on Hamming distance.

[0021] A longitudinal protection system for power transmission lines from new energy power plants based on Hamming distance, comprising:

[0022] The current sampling value acquisition module is used to acquire the current sampling values ​​after the protection on the station side and system side of the transmission line is started.

[0023] The data preprocessing module is used to preprocess the current sampling values ​​of the station side and system side of the transmission line to obtain a first numerical sequence and a second numerical sequence containing 0 and 1 respectively.

[0024] The Hamming distance calculation module is used to calculate the Hamming distance based on the ratio of the number of different sampling points between the first and second numerical sequences to the number of sampling points of the sampling window length.

[0025] The trip command issuing module is used to determine the fault type based on the size of the Hamming distance, and then, by comparing the Hamming distance with the set value of the Hamming distance, to determine whether to issue a trip command to the protection devices on the station side and system side of the sending line.

[0026] As one implementation method, in the trip command issuing module, during the process of determining the fault type based on the magnitude of the Hamming distance:

[0027] When the Hamming distance is 0, it is determined to be an out-of-area fault;

[0028] When the Hamming distance is greater than 0, it is determined to be an intra-zone fault.

[0029] As one implementation method, in the trip command issuing module, when a fault is determined to be within the zone and the Hamming distance is greater than the set value of the Hamming distance, a trip command is issued to the protection devices on the station side and the system side of the sending line, respectively.

[0030] As one implementation, the Hamming distance is set to the product of the phase angle error caused by CT transmission and distributed capacitance and the margin coefficient that retains the set margin.

[0031] As one implementation method, the process of preprocessing the current sampling values ​​on the station side and system side of the transmitting line includes:

[0032] For either the station side or the system side of the transmitting line, first take the negative value of the current on the opposite side, then calculate the average value of the current sampling value. When the current signal sampling value is greater than or equal to the average value, the corresponding current signal sampling value is set to 1; when the current signal sampling value is less than the average value, the corresponding current signal sampling value is set to 0.

[0033] A third aspect of the present invention provides a computer-readable storage medium.

[0034] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the longitudinal protection method for the transmission lines of new energy power plants based on Hamming distance as described above.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] This invention does not rely on power frequency fault characteristics and has good operating performance; it can withstand high-impedance faults, ensuring the reliability of the new protection principle; the protection operates within 10ms, exhibiting good speed.

[0037] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0038] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0039] Figure 1 This is a schematic diagram illustrating the novel protection principle of Hamming distance proposed in this invention;

[0040] Figure 2 A schematic diagram showing the location and topology of the fault in the power transmission line of a new energy power station;

[0041] Figure 3 This is a schematic diagram of the protective device's operating logic.

[0042] Figure 4 This is a schematic diagram of a single-phase fault protection system.

[0043] Figure 5 This is a schematic diagram of a two-phase interphase fault protection system.

[0044] Figure 6 This is a schematic diagram of a two-phase ground fault protection system.

[0045] Figure 7 This is a schematic diagram of a three-phase fault protection system. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0047] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0048] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0049] according to Figure 1 This paper provides a longitudinal protection method for power transmission lines of new energy power plants based on Hamming distance, which includes:

[0050] Step 1: Obtain the current sampling values ​​after the protection is activated on the substation side and system side of the transmitting line;

[0051] Step 2: Perform data preprocessing on the current sampling values ​​of the station side and system side of the transmission line to obtain a first numerical sequence and a second numerical sequence containing 0 and 1 respectively.

[0052] Specifically, the process of preprocessing the current sampling values ​​on the station side and system side of the transmitting line includes:

[0053] For either the station side or the system side of the transmitting line, first take the negative value of the current on the opposite side, then calculate the average value of the current sampling value. When the current signal sampling value is greater than or equal to the average value, the corresponding current signal sampling value is set to 1; when the current signal sampling value is less than the average value, the corresponding current signal sampling value is set to 0.

[0054] Step 3: Calculate the Hamming distance based on the ratio of the number of different sampling points between the first and second numerical sequences to the number of sampling points in the sampling window.

[0055] φ = A, B, C

[0056] Where, d φ For the improved Hamming distance of three phases A, B, and C, H φ N represents the number of different sampling points in the sequence after preprocessing the currents on both sides; N is the number of sampling points for a sampling window.

[0057] Step 4: Determine the fault type based on the size of the Hamming distance, and then, based on the comparison between the Hamming distance and its setting value, determine whether to issue a trip command to the protection devices on the station side and system side of the sending line.

[0058] In step 4, during the process of determining the fault type based on the magnitude of the Hamming distance:

[0059] When the Hamming distance is 0, it is determined to be an out-of-area fault;

[0060] When the Hamming distance is greater than 0, it is determined to be an intra-zone fault.

[0061] The Hamming distance between the current sampling values ​​on both sides differs significantly between faults within and outside the fault zone.

[0062] 1) When there is a fault outside the zone, considering the setting of the positive direction of the current and the negative processing of the sampled current value on the opposite side during preprocessing, the numerical sequences on both sides are the same, and the Hamming distance is 0.

[0063] 2) When there is a fault in the zone, the current waveforms on both sides are significantly different, resulting in a significant difference in the numerical sequences on both sides, with the Hamming distance being greater than 0.

[0064] Specifically, when a fault is determined to be within the zone and the Hamming distance is greater than the set value of the Hamming distance, tripping commands are issued to the protection devices on the station side and system side of the sending line, respectively.

[0065] The Hamming distance setting is the product of the phase angle error caused by CT transmission and distributed capacitance and the margin coefficient that retains the set margin.

[0066] d set =K arg ·K var

[0067] In the formula, K arg To account for the phase angle error caused by CT transmission and distributed capacitance, K var A margin factor to retain a certain margin.

[0068] Based on the selection of the coefficients mentioned above, K caused by the phase angle error arg The value is set to 0.05, and with a margin of 1.5, the final value is set to 0.1.

[0069] After the protection is activated, if an external fault occurs and the protection setting criteria are not met, the protection device will not issue a trip command. If an internal fault occurs, if the protection setting criteria are met for any one of the three phases A, B, and C, the protection device will issue a single-phase trip command. If the protection setting criteria are met for any two or all three phases, the protection device will issue a three-phase trip command.

[0070] Figure 2 The diagram shows the location and topology of a fault in the transmission line of a new energy power plant. The new energy power plants in the diagram include three types: doubly fed wind farms, permanent magnet wind farms, and photovoltaic power plants. Figure 2 The total capacity of the new energy power station shown is 100MW. For the three types of power stations, the generator terminal voltage is 0.69kV, the transformer ratio is 35kV / 0.69kV, using Dyn connection, with a short-circuit impedance of 8.42%; the main transformer ratio is 220kV / 35kV, using YNd connection, with a short-circuit impedance of 7.28%. The positive and negative sequence impedances per kilometer of transmission line are both 0.028+j0.147Ω, the unit zero-sequence impedance is 0.144+j0.746Ω, and the transmission line length is 20km. Based on... Figure 2 The electromagnetic transient model of a centralized grid-connected power transmission system of a wind farm was built in a real-time digital simulator (RTDS) using the topology and the parameters mentioned above to verify the protection algorithm proposed in this invention.

[0071] Five fault locations are set, including two external faults and three internal faults. External faults are set outside the system side and outside the station side, respectively. Internal faults are set at the line midpoint, system side, and near the station side, respectively. To ensure that the proposed new protection principle can operate correctly under various fault types, the fault types set include single-phase faults, two-phase faults, two-phase ground faults, and three-phase faults.

[0072] Figure 3 This is a schematic diagram of the protection device's operating logic. It uses the sudden change in current as the starting criterion. When a fault occurs, the protection criterion of the protection device is activated. When a fault occurs within the zone, depending on whether it is a single-phase fault, a two-phase fault, or a three-phase fault, the corresponding phase improved Hamming distance is greater than the setting value, and the protection device issues the corresponding trip command. When a fault occurs outside the zone, the three-phase improved Hamming distances are all less than the setting value, and the protection device resets.

[0073] Figure 4 , Figure 5 , Figure 6 , Figure 7 These are the protection operation performances of the new protection principles proposed for different types of faults within the zone, among which... Figure 4 For the operating performance under single-phase fault, Figure 5 For the operating performance under two-phase inter-phase fault, Figure 6 For the operating performance under two-phase ground fault, Figure 7 The diagram illustrates the operating performance under three-phase faults. Solid lines represent the setting values, dashed lines represent the improved Hamming distance for phase A, dotted lines represent the improved Hamming distance for phase B, and dashed-dot lines represent the improved Hamming distance for phase C. By comparing the operating performance of the new protection principle under different types of faults, the proposed protection can correctly identify faults within 10ms, demonstrating excellent operating performance.

[0074] To further verify the effectiveness of the novel protection principle proposed in this invention, simulation verification was conducted. Table 1 shows the Hamming distance values ​​under different fault locations and fault types during metallic faults. The calculated values ​​in the table are the improved Hamming distances obtained after taking the sampling window length 10 ms after the fault occurs. Table 2 presents the operational performance of the proposed novel protection principle under single-phase and two-phase-to-ground faults with different transition resistances. The calculated values ​​in the table are the Hamming distances obtained after taking the sampling window length 10 ms after the fault occurs. Table 3 shows the operational performance of the proposed protection under different levels of noise for different types of faults.

[0075] Table 1. Hamming distance values ​​for different fault locations and fault types during metallic faults.

[0076]

[0077]

[0078] Table 2. Operating performance of the proposed new protection principle under single-phase and two-phase ground faults with different transition resistances.

[0079]

[0080] Table 3. Protection action performance under different noise levels and for different types of faults.

[0081]

[0082]

[0083] Experimental results show that the proposed new protection principle has good operating performance, and can correctly determine the fault inside and outside the zone under different types and fault locations within 10ms; the new protection principle can withstand high resistance faults, and can operate correctly with a transition resistance of 100Ω in both single-phase grounding and two-phase grounding cases; the proposed new protection principle can withstand a certain degree of noise, and the protection still has reliability and can correctly identify the faulty phase and non-faulty phase.

[0084] Given the analytical basis and conditions of this method, the application of the method described in this invention is not affected by the operating conditions of the wind farm grid-connected system (such as capacity, operating mode, etc.) and the inverter control strategy, and can avoid the risk of decreased sensitivity or even failure to operate correctly of existing phasor differential protection.

[0085] In one or more embodiments, a longitudinal protection system for power transmission lines from new energy power plants based on Hamming distance is also provided, comprising:

[0086] The current sampling value acquisition module is used to acquire the current sampling values ​​after the protection on the station side and system side of the transmission line is started.

[0087] The data preprocessing module is used to preprocess the current sampling values ​​of the station side and system side of the transmission line to obtain a first numerical sequence and a second numerical sequence containing 0 and 1 respectively.

[0088] The Hamming distance calculation module is used to calculate the Hamming distance based on the ratio of the number of different sampling points between the first and second numerical sequences to the number of sampling points of the sampling window length.

[0089] The trip command issuing module is used to determine the fault type based on the size of the Hamming distance, and then, by comparing the Hamming distance with the set value of the Hamming distance, to determine whether to issue a trip command to the protection devices on the station side and system side of the sending line.

[0090] In the trip command issuance module, during the process of determining the fault type based on the Hamming distance:

[0091] When the Hamming distance is 0, it is determined to be an out-of-area fault;

[0092] When the Hamming distance is greater than 0, it is determined to be an intra-zone fault.

[0093] In the trip command issuance module, when a fault is determined to be within the zone and the Hamming distance is greater than the set value of the Hamming distance, a trip command is issued to the protection devices on the station side and the system side of the sending line, respectively.

[0094] Specifically, the Hamming distance setting is the product of the phase angle error caused by CT transmission and distributed capacitance and the margin coefficient that retains the set margin.

[0095] In the specific implementation process, the data preprocessing of the current sampling values ​​on the station side and system side of the transmitting line includes:

[0096] For either the station side or the system side of the transmitting line, first take the negative value of the current on the opposite side, then calculate the average value of the current sampling value. When the current signal sampling value is greater than or equal to the average value, the corresponding current signal sampling value is set to 1; when the current signal sampling value is less than the average value, the corresponding current signal sampling value is set to 0.

[0097] One or more embodiments provide a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps in the longitudinal protection method for the transmission lines of new energy power stations based on Hamming distance as described above.

[0098] One or more embodiments provide an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps in the longitudinal protection method for the transmission lines of new energy power plants based on Hamming distance as described above.

[0099] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0100] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A longitudinal protection method for power transmission lines of new energy power plants based on Hamming distance, characterized in that, include: Obtain the current sampling values ​​after the protection on the station side and system side of the transmission line is activated; The current sampling values ​​on the station side and system side of the transmission line are preprocessed to obtain a first numerical sequence and a second numerical sequence containing 0 and 1, respectively. The Hamming distance is calculated based on the ratio of the number of different sampling points between the first and second numerical sequences to the number of sampling points in the sampling window. The fault type is determined based on the magnitude of the Hamming distance. Then, by comparing the Hamming distance with the set value of the Hamming distance, it is determined whether to issue a trip command to the protection devices on the station side and system side of the sending line.

2. The longitudinal protection method for new energy power station transmission lines based on Hamming distance as described in claim 1, characterized in that, In the process of determining the fault type based on the magnitude of the Hamming distance: When the Hamming distance is 0, it is determined to be an out-of-area fault; When the Hamming distance is greater than 0, it is determined to be an intra-zone fault.

3. The longitudinal protection method for new energy power station transmission lines based on Hamming distance as described in claim 2, characterized in that, When a fault is determined to be within the zone and the Hamming distance is greater than the set value of the Hamming distance, tripping commands are issued to the protection devices on the station side and system side of the sending line, respectively.

4. The longitudinal protection method for new energy power station transmission lines based on Hamming distance as described in claim 1, characterized in that, The Hamming distance setting is the product of the phase angle error caused by CT transmission and distributed capacitance and the margin coefficient that retains the set margin.

5. The longitudinal protection method for power transmission lines of new energy power plants based on Hamming distance as described in claim 1, characterized in that, The process of preprocessing the current sampling values ​​on the station side and system side of the transmission line includes: For either the station side or the system side of the transmitting line, first take the negative value of the current on the opposite side, then calculate the average value of the current sampling value. When the current signal sampling value is greater than or equal to the average value, the corresponding current signal sampling value is set to 1; when the current signal sampling value is less than the average value, the corresponding current signal sampling value is set to 0.

6. A longitudinal protection system for power transmission lines of new energy power plants based on Hamming distance, characterized in that, include: The current sampling value acquisition module is used to acquire the current sampling values ​​after the protection on the station side and system side of the transmission line is started. The data preprocessing module is used to preprocess the current sampling values ​​of the station side and system side of the transmission line to obtain a first numerical sequence and a second numerical sequence containing 0 and 1 respectively. The Hamming distance calculation module is used to calculate the Hamming distance based on the ratio of the number of different sampling points between the first and second numerical sequences to the number of sampling points of the sampling window length. The trip command issuing module is used to determine the fault type based on the size of the Hamming distance, and then, by comparing the Hamming distance with the set value of the Hamming distance, to determine whether to issue a trip command to the protection devices on the station side and system side of the sending line.

7. The longitudinal protection system for new energy power station transmission lines based on Hamming distance as described in claim 6, characterized in that, In the trip command issuance module, during the process of determining the fault type based on the Hamming distance: When the Hamming distance is 0, it is determined to be an out-of-area fault; When the Hamming distance is greater than 0, it is determined to be an intra-zone fault.

8. The longitudinal protection system for new energy power station transmission lines based on Hamming distance as described in claim 7, characterized in that, In the trip command issuance module, when a fault is determined to be within the zone and the Hamming distance is greater than the set value of the Hamming distance, a trip command is issued to the protection devices on the station side and the system side of the sending line, respectively.

9. The longitudinal protection system for new energy power station transmission lines based on Hamming distance as described in claim 6, characterized in that, The Hamming distance setting is the product of the phase angle error caused by CT transmission and distributed capacitance and the margin coefficient that retains the set margin. or The process of preprocessing the current sampling values ​​on the station side and system side of the transmission line includes: For either the station side or the system side of the transmitting line, first take the negative value of the current on the opposite side, then calculate the average value of the current sampling value. When the current signal sampling value is greater than or equal to the average value, the corresponding current signal sampling value is set to 1; when the current signal sampling value is less than the average value, the corresponding current signal sampling value is set to 0.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the longitudinal protection method for the transmission lines of new energy power stations based on Hamming distance as described in any one of claims 1-5.

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