Power distribution network protection method, system and equipment of distributed power supply and medium

Abstract

The invention discloses a power distribution network protection method, system and device for a distributed power supply and a medium, and the method comprises the steps: obtaining current data and voltage data of a key node of a power distribution network, and setting a second harmonic content threshold value and a voltage threshold value coefficient; calculating a second harmonic ratio based on the current data, performing first judgment on the second harmonic ratio and the second harmonic content threshold value, and identifying excitation surge current according to a first judgment result; and performing second judgment on the voltage data and the voltage threshold based on the first judgment result, and correcting the second harmonic content threshold according to the second judgment result to realize protection of the power distribution network of the distributed power supply, so that the response to the fluctuation of the second harmonic content is more timely.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, in particular to a power distribution network protection method, system, device and medium of distributed power supply. BACKGROUND

[0002] At present, a large number of distribution transformers are installed on 10kV distribution network lines, and the switching of distribution transformers will cause the misoperation and refusal of protection devices, seriously affecting the safe and stable operation of the distribution network and greatly reducing the power supply reliability. The access of distributed new energy represented by wind power and photovoltaic power has changed the characteristics of one-way energy flow of the traditional distribution network, and the intermittency, volatility and uncertainty of power generation have brought great challenges to the protection and control of the distribution network. Therefore, with the increasing use of large-capacity transformers and distributed power supplies, correctly handling the misoperation and refusal caused by the inrush current and the load access of the distribution network is an effective measure to continuously improve the power supply reliability of the distribution network system.

[0003] The present application researches the characteristics of the inrush current in the distribution network and its influence on the protection of the distribution network by learning from the experience of the inrush current waveform recognition method of the transmission network main transformer, and forms a waveform recognition method suitable for the distribution network. By analyzing the structure, principle and voltage characteristics of different distributed power supplies, the interactive influence of the new energy control system and the inrush current when the distributed power supply is accessed, and the influence of the inverter system on the direct current magnetic bias of the distribution transformer, the recognition scheme of the inrush current when the new energy is accessed is completed. SUMMARY

[0004] In view of the above existing problems, the present application provides a power distribution network protection method, system, device and medium of distributed power supply.

[0005] The present application provides a power distribution network protection method, system, device and medium of distributed power supply to solve the misoperation and refusal of protection devices caused by the access of distributed power supply in the existing distribution network.

[0006] To solve the above technical problems, the present application provides the following technical scheme: In a first aspect, the present application provides a power distribution network protection method of distributed power supply, comprising: Obtaining current data and voltage data of a key node of the power distribution network, and setting a second harmonic content threshold and a voltage threshold coefficient; Based on the current data, the second harmonic ratio is calculated, the second harmonic ratio is compared with the second harmonic content threshold for first judgment, and the inrush current is identified according to the first judgment result; Based on the first judgment result, the voltage data and the voltage threshold are compared for second judgment, the second harmonic content threshold is modified according to the second judgment result, and the protection of the power distribution network of the distributed power supply is realized.

[0007] In a preferred embodiment of the distribution network protection method for distributed power sources according to the present invention, the first determination of the second harmonic ratio and the second harmonic content threshold includes: Calculate the fundamental amplitude and second harmonic amplitude based on the current data; The second harmonic ratio is obtained based on the mathematical relationship between the amplitude of the second harmonic and the amplitude of the fundamental wave. If the second harmonic ratio is greater than the second harmonic content threshold, it is judged as inrush current. If the second harmonic ratio is less than the second harmonic content threshold, it is judged as distributed current interference or short circuit fault, and a second judgment is made.

[0008] The beneficial effect of this preferred technical solution is that by judging the second harmonic ratio, it can effectively distinguish between inrush current and distributed power supply interference or short circuit fault, thereby improving the accuracy of protection.

[0009] As a preferred embodiment of the distribution network protection method for distributed power sources described in this invention, it further includes: Set boundary parameters to characterize the allowable deviation; When the second harmonic ratio is less than the second harmonic content threshold, the deviation of the second harmonic ratio is compared with the boundary parameters. If the deviation of the second harmonic ratio is less than or equal to the boundary parameter, then the sampling period is increased. If the deviation of the second harmonic ratio is always less than or equal to the boundary parameter during the additional sampling period, then a second judgment is made. Otherwise, it is considered that the second harmonic ratio is greater than the second harmonic content threshold, and it is re-judged as an inrush current.

[0010] The beneficial effects of this preferred technical solution are that by introducing boundary parameters and additional sampling, false judgments are reduced and protection reliability is improved.

[0011] In a preferred embodiment of the distribution network protection method for distributed power sources according to the present invention, the second determination of the voltage data and the voltage threshold includes: Obtain rated voltage data; If the voltage data is less than or equal to the product of the voltage threshold coefficient and the rated voltage data, it is judged as a short circuit fault; If the voltage data is greater than the product of the voltage threshold coefficient and the rated voltage data, it is determined to be a fluctuation in the second harmonic content caused by interference from distributed power sources.

[0012] The beneficial effect of this preferred technical solution is that it can accurately distinguish between short-circuit faults and distributed power source interference by judging voltage thresholds, thereby improving protection accuracy.

[0013] As a preferred embodiment of the distribution network protection method for distributed power sources described in this invention, it further includes: If the voltage data is less than or equal to the product of the voltage threshold coefficient and the rated voltage data, then an additional sampling period is added; During the additional sampling period, the voltage data is continuously assessed for abnormal states. If the voltage data continuously meets the criteria for short-circuit fault during the additional sampling period, it is judged as a short-circuit fault. Otherwise, the voltage data is considered to be within the normal range.

[0014] As a preferred embodiment of the distribution network protection method for distributed power sources according to the present invention, the correction of the second harmonic content threshold includes: When the second harmonic ratio is less than the second harmonic content threshold and the voltage data is greater than the product of the voltage threshold coefficient and the rated voltage data, the average of the second harmonic ratio and the second harmonic content threshold is taken to obtain the corrected second harmonic content threshold.

[0015] As a preferred embodiment of the distribution network protection method for distributed power sources described in this invention, it further includes: A time threshold is set for the corrected second harmonic content threshold; When the distribution network does not trigger the time threshold correction within the time interval, the second harmonic content threshold will be corrected to the initial second harmonic content threshold.

[0016] Secondly, the present invention provides a distribution network protection system for distributed power sources, comprising: The data acquisition module is used to acquire current and voltage data of key nodes in the distribution network, and to set the second harmonic content threshold and voltage threshold coefficient. The first judgment module is used to calculate the second harmonic ratio based on the current data, make a first judgment between the second harmonic ratio and the second harmonic content threshold, and identify the inrush current based on the first judgment result. The second judgment module is used to make a second judgment on the voltage data and the voltage threshold based on the first judgment result, and to correct the second harmonic content threshold according to the second judgment result, so as to realize the protection of the distribution network of distributed power sources.

[0017] Thirdly, the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, characterized in that the processor executes the computer program to implement the steps of the distributed power supply distribution network protection method.

[0018] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, characterized in that, when the computer program is executed by a processor, it implements the steps of the distribution network protection method for the distributed power source.

[0019] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention compares the second harmonic content with a second harmonic content threshold, and identifies inrush current based on the comparison result. The inrush current identified by this invention can prevent protection devices from malfunctioning or failing to operate. The identification of inrush current in this invention can improve the reliability of distribution network protection. This invention introduces a voltage dip judgment mechanism, which determines whether a short-circuit fault or distributed generation (DG) interference is caused by setting the rated system voltage value and a threshold coefficient. The voltage dip judgment mechanism in this invention can effectively distinguish between short-circuit faults and DG interference. This invention avoids misjudgments caused by the connection of DG by differentiating faults, and the voltage dip judgment mechanism ensures the stable operation of the distribution network. When the invention determines that it is DG interference, it corrects the second harmonic content threshold based on the second harmonic content being less than the second harmonic content threshold. This invention sets a time threshold, and when the system does not trigger threshold correction for a continuous period of time, the second harmonic content threshold is restored to its initial value. The present invention corrects the second harmonic content threshold to adapt to the intermittency and volatility of distributed power sources. The present invention can also prevent the threshold from deviating too much from the initial setting, thereby improving the adaptability and reliability of the system of the present invention. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall process logic of a distributed power supply network protection method provided in an embodiment of the present invention. Detailed Implementation

[0022] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0023] Example 1, referring to Figure 1As an embodiment of the present invention, a distribution network protection method for distributed power sources is provided, comprising: S100: Acquire current and voltage data of key nodes in the distribution network, and set the second harmonic content threshold and voltage threshold coefficient. In this embodiment of the invention, current transformers (CTs) and voltage transformers (VTs) are installed at key nodes of the distribution network, such as the DG (distributed generation) grid connection point, to achieve real-time sampling of current and voltage. The sampling frequency is not less than 2kHz (the grid frequency is 50Hz) to ensure the accuracy and completeness of the sampling. Set the initial second harmonic content threshold It can be between 15% and 20%.

[0024] It should be noted that a high sampling frequency ensures data accuracy, and combined with reasonable threshold settings, it accurately monitors the status of the power distribution network, effectively improving the reliability and response speed of protection devices and ensuring the stable operation of the power grid.

[0025] S200: Calculates the second harmonic ratio based on current data, makes a first judgment between the second harmonic ratio and the second harmonic content threshold, and identifies the inrush current based on the first judgment result; S300: Based on the first judgment result, the voltage data and voltage threshold are judged in the second judgment, and the second harmonic content threshold is corrected according to the second judgment result to realize the protection of the distribution network of distributed power sources.

[0026] In one optional embodiment, the second harmonic content threshold can be corrected by a weighted average correction method. When the threshold correction condition is met, the current second harmonic ratio and the current threshold are obtained. A new weighting factor and an old threshold weighting factor are preset. The current second harmonic ratio and the current threshold are weighted and summed to obtain the corrected second harmonic content threshold. In another optional embodiment, the second harmonic content threshold can also be corrected by the sliding window mean correction method. When the threshold correction condition is met, all second harmonic ratios that meet the condition at the current time and in the previous period are recorded to form a data set. The arithmetic mean of this data set is calculated, and the new second harmonic content threshold is updated to the mean. In this embodiment of the invention, the correction of the second harmonic content threshold includes: when the second harmonic ratio is less than the second harmonic content threshold and the voltage data is greater than the product of the voltage threshold coefficient and the rated voltage data, the second harmonic content threshold will be updated according to a preset correction strategy, that is, a new threshold will be calculated and assigned. To prevent the threshold from deviating too much from its initial design value after long-term adjustments, thus reducing protection performance, a recovery mechanism is implemented. That is, if the system does not trigger threshold adjustments again for a continuous period, the current threshold will be restored or gradually approached from the initial setting.

[0027] It should be noted that by dynamically adjusting the threshold, the system can adapt to changes in distributed power source interference, improve protection flexibility, and the recovery mechanism prevents the threshold from deviating excessively from the initial value, ensuring long-term stable and reliable protection performance and enhancing system adaptability and reliability.

[0028] In this embodiment of the invention, step S200 includes the following sub-steps A1-A4; In A1: Calculate the fundamental amplitude and second harmonic amplitude based on the current data; In A2: the second harmonic ratio is obtained based on the mathematical relationship between the second harmonic amplitude and the fundamental amplitude; In A3: If the second harmonic ratio is greater than the second harmonic content threshold, it is judged as inrush current. In A4: If the second harmonic ratio is less than the second harmonic content threshold, it is judged as distributed current interference or short circuit fault, and a second judgment is made.

[0029] In one optional embodiment, the second harmonic ratio can be calculated by separately calculating the energy of the fundamental component and the energy of the second harmonic component, taking the sum of squares or root mean square of the sampled values ​​of the fundamental current and the second harmonic current, and calculating the energy ratio parameter, i.e., the second harmonic ratio, based on the energy value and the ratio of the second harmonic energy to the fundamental energy. In another optional embodiment, the second harmonic ratio can also be calculated by extracting a current waveform signal of one cycle from the collected current data. Based on the fundamental frequency, amplitude, and phase of the current signal, a standard sine wave of the same frequency and phase is generated as a reference signal, and the difference between the measured current waveform and the standard sine reference waveform is calculated, i.e., the second harmonic ratio. In this embodiment of the invention, the second harmonic ratio is obtained based on the ratio of the second harmonic amplitude to the fundamental amplitude; Specifically, inrush current is identified based on the initial second harmonic content threshold, including: Calculate the fundamental amplitude and the second harmonic amplitude separately. The fundamental amplitude refers to the maximum value of the sinusoidal current, usually expressed as the square root of the effective value or average value, as follows: in, The fundamental amplitude, For instantaneous current, Angular frequency, For time, The initial phase angle; The amplitude of the second harmonic of a current refers to the amplitude of the component in the current waveform that has a frequency twice that of the fundamental frequency in a power system. For example, if the fundamental frequency is 50Hz and the second harmonic frequency is 100Hz, its amplitude reflects the proportion of this component in the current.

[0030] The second harmonic ratio, calculated based on the amplitude of the second harmonic and the amplitude of the fundamental frequency, is expressed as: in, The amplitude of the second harmonic. The fundamental amplitude, It is the second harmonic ratio.

[0031] like At that time, it was determined to be an inrush current; when When this occurs, it is determined to be a distributed power source interference or short circuit fault.

[0032] It should be noted that by accurately calculating the second harmonic ratio and combining it with high sampling frequency data, the system can effectively distinguish between inrush current and distributed power source interference or short-circuit faults, thereby improving the accuracy and reliability of distribution network protection, reducing the false judgment rate, and ensuring power supply stability.

[0033] In this embodiment of the invention, after completing steps A1-A4, step S200 also includes steps A5-A9; In A5: Set the boundary parameters that characterize the allowable deviation; In A6: When the second harmonic ratio is less than the second harmonic content threshold, the deviation of the second harmonic ratio is compared with the boundary parameter. In A7: If the deviation of the second harmonic ratio is less than or equal to the boundary parameter, then the sampling period is increased; In A8: If the deviation of the second harmonic ratio is always less than or equal to the boundary parameter during the additional sampling period, then a second judgment is made; In A9: Otherwise, it is considered that the second harmonic ratio is greater than the second harmonic content threshold, and it is re-judged as an inrush current.

[0034] In an optional embodiment, the deviation of the second harmonic ratio can be a relative deviation. The relative deviation is obtained by dividing the difference between the second harmonic content threshold and the second harmonic ratio by the second harmonic content threshold, and the relative deviation is then determined relative to the boundary parameter. In another optional embodiment, the deviation of the second harmonic ratio can also be determined by statistical fluctuation. If the second harmonic ratio is less than the second harmonic content threshold and enters the buffer criterion, additional sampling for N cycles is immediately started. In each sampling cycle, it is determined whether the absolute difference between the second harmonic ratio and the second harmonic content threshold is less than the boundary parameter. In this embodiment of the invention, the deviation of the second harmonic ratio is the absolute value of the difference between the second harmonic ratio and the second harmonic content threshold. Specifically, set buffer boundaries , can take 2%, when At that time, make a judgment and Size relationship; when At that time, additional sampling is performed for N periods. Within these N periods, Always less than or equal to If yes, execute the second judgment; otherwise, consider it as... .

[0035] It should be noted that by setting buffer boundaries and introducing an additional sampling mechanism, the present invention effectively distinguishes between transient harmonic fluctuations caused by electromagnetic interference and actual fault states, significantly reducing the risk of misjudgment and failure to operate in the protection system and improving power supply reliability.

[0036] It should also be noted that the sampling data in the distribution network is subject to electromagnetic interference, and there are errors between the sampling data and the actual data, which will cause data fluctuations. In addition, there are a lot of "transient harmonic mutations" in the distribution network, while the data tends to be steady during short-circuit faults. By setting a buffer boundary and judging the state of K value, misjudgments of various situations can be avoided.

[0037] In this embodiment of the invention, step S300 includes the following sub-steps B1-B3; In B1: Obtain the rated voltage data; In B2: If the voltage data is less than or equal to the product of the voltage threshold coefficient and the rated voltage data, it is judged as a short circuit fault; In B3: If the voltage data is greater than the product of the voltage threshold coefficient and the rated voltage data, it is judged to be a fluctuation in the second harmonic content caused by distributed power source interference.

[0038] In this embodiment of the invention, the second determination is based on the result of the first determination, when If the fault is determined to be distributed power interference or a short circuit fault, a second judgment is triggered to further distinguish between short circuit faults and distributed power interference.

[0039] Set the rated system voltage value Obtain the real-time system voltage value V; Short-circuit faults are identified based on voltage sag values, which are derived from real-time system voltage values ​​acquired via voltage transformers (VT). This value is related to the set rated system voltage value. Compare. Voltage sag is typically defined as ( This invention directly uses and The degree of fall is judged by comparison.

[0040] when When the fault is detected, it is determined to be a short circuit fault. when At that time, it was determined to be a fluctuation in the second harmonic content caused by interference from distributed power sources; It is the set threshold coefficient. .

[0041] It should be noted that by comparing the voltage drop value with the threshold coefficient, short-circuit faults and distributed power source interference can be accurately distinguished, avoiding misjudgment, improving the reliability and accuracy of the protection system, and effectively ensuring the safe and stable operation of the distribution network.

[0042] In this embodiment of the invention, after completing steps B1-B3, step S300 also includes steps B4-B7. In B4: If the voltage data is less than or equal to the product of the voltage threshold coefficient and the rated voltage data, then an additional sampling period is added; In B5: During the additional sampling period, the voltage data is continuously assessed for abnormal states; In B6: If the voltage data continuously meets the judgment condition for short circuit fault during the additional sampling period, it is judged as a short circuit fault; In B7: Otherwise, the voltage data is judged to be a normal fluctuation.

[0043] In one optional embodiment, the short-circuit fault determination condition can be based on voltage-current correlation characteristics. When the voltage data is less than or equal to the product of the voltage threshold coefficient and the rated voltage data, an additional sampling period is initiated, and the current data at that moment is simultaneously locked as a reference. During the additional sampling period, the voltage and current data are continuously monitored. If the voltage data remains below the threshold, and simultaneously, the ratio of the real-time current data to the reference current exceeds a preset current increment coefficient, and the voltage and current data simultaneously and continuously meet the above joint determination condition during the additional sampling period, then a short-circuit fault is ultimately determined. If either the voltage or current condition is not met during the additional sampling period, then the voltage drop is determined to be a normal fluctuation. In another optional embodiment, the short-circuit fault determination condition can also be based on voltage drop depth and recovery gradient. When the voltage data satisfies the condition that the voltage data is less than or equal to the product of the voltage threshold coefficient and the rated voltage data, an additional sampling period is initiated, and the initial voltage drop value is recorded. During the additional sampling period, the voltage data is continuously monitored. The determination condition is supplemented with two sub-conditions: the voltage data is always lower than a depth action threshold that is more stringent than the product of the voltage threshold coefficient and the rated voltage data; the voltage recovery gradient is calculated, and if this gradient is less than a preset recovery gradient threshold, and the voltage data continuously satisfies both the depth condition and the trend condition during the additional sampling period, then it is determined to be a short-circuit fault. If, during the additional sampling period, the voltage recovers to above the depth action threshold, or the recovery gradient exceeds the recovery gradient threshold, then it is determined to be a normal fluctuation caused by transient interference.

[0044] In this embodiment of the invention, the criteria for determining a short-circuit fault include setting an additional sampling period N, when... At that time, additional sampling is performed for N periods. Within these N periods, Always less than or equal to If the condition is positive, it is ultimately determined to be a short circuit fault; otherwise, it is determined to be a normal fluctuation.

[0045] It should be noted that adding a sampling period ensures the accuracy of short-circuit fault diagnosis, avoids misjudgment due to instantaneous voltage fluctuations, improves system reliability, and ensures stable operation of the distribution network.

[0046] In this embodiment of the invention, after completing steps B4-B7, step S300 further includes steps B8-B10. In B8: When the second harmonic ratio is less than the second harmonic content threshold and the voltage data is greater than the product of the voltage threshold coefficient and the rated voltage data, the average of the sum of the second harmonic ratio and the second harmonic content threshold is taken to obtain the corrected second harmonic content threshold. In B9: Set a time threshold for the corrected second harmonic content threshold; In B10: When the distribution network does not trigger the time threshold correction within the time interval, the second harmonic content threshold is corrected to the initial second harmonic content threshold.

[0047] In this embodiment of the invention, when ,and When, make corrections The value is represented as: For the new The value is the corrected second harmonic content threshold.

[0048] Second harmonic content threshold recovery; Set a time threshold When the distribution network is in time interval If the threshold correction is not triggered within the specified time, then... Revert to the initial value.

[0049] In one optional embodiment, the time threshold can be set using a dynamic adjustment method based on the system disturbance frequency. This involves continuously monitoring and recording the triggering of threshold correction conditions within a unit of time, with a preset base time, such as 600 seconds, and a frequency coefficient. The dynamic time threshold is calculated based on the current disturbance frequency and used as the waiting time to determine whether to restore the second harmonic content threshold to its initial value. Simultaneously, the threshold correction conditions are periodically reset, such as every 24 hours, and statistics are restarted to adapt to different operating phases of the system. In another optional embodiment, the time threshold can be set as a step-by-step recovery method based on the degree of threshold deviation. When the system meets the recovery condition (i.e., enters the waiting recovery timing state), the relative deviation between the current second harmonic content threshold and the initial value is calculated, a recovery step size is preset, such as 1% of the initial value, and a short recovery period T, such as 60 seconds, is used. After each recovery period T, the system automatically moves the current threshold one step closer to the initial value until it returns to the initial value or the recovery process is interrupted due to new disturbances during this period. In this embodiment of the invention, the time threshold The setting is based on the operating characteristics and historical data of the distribution network, and is usually set to 5-10 minutes (300-600 seconds) to ensure that the system recovers stability after a short period of fluctuation.

[0050] Time threshold The response time of the protection system is determined based on the typical interference cycle of distributed power sources in the distribution network and can be adjusted through simulation testing or field experience.

[0051] For example, in an embodiment, The initial time can be set to 600 seconds. If the system does not trigger the threshold correction within 600 seconds, that is, if the second harmonic ratio is not less than the second harmonic content threshold and the voltage data is greater than the product of the voltage threshold coefficient and the rated voltage data, the second harmonic content threshold will be automatically restored to the initial value.

[0052] It should be noted that the time threshold is set based on the operating characteristics of the distribution network and the interference cycle of distributed power sources to ensure that the system recovers stability after a brief fluctuation. The time threshold is adjusted through simulation testing or field experience. If the threshold correction is not triggered within 600 seconds, the second harmonic content threshold is automatically restored to its initial value. This mechanism effectively prevents the threshold from deviating excessively from the initial setting, avoids a decline in protection performance due to long-term corrections, significantly improves the long-term stability and reliability of the system, and ensures the accuracy and adaptability of the distribution network protection function.

[0053] The above is a schematic scheme of the distribution network protection method for distributed power sources according to this embodiment. It should be noted that the technical solution of this distributed power source distribution network protection system belongs to the same concept as the technical solution of the distributed power source distribution network protection method described above. Details not described in detail in the technical solution of the distributed power source distribution network protection system in this embodiment can be found in the description of the technical solution of the distributed power source distribution network protection method described above.

[0054] The distribution network protection system for distributed power sources in this embodiment includes: The data acquisition module is used to acquire current and voltage data of key nodes in the distribution network, and to set the second harmonic content threshold and voltage threshold coefficient. The first judgment module is used to calculate the second harmonic ratio based on the current data, make a first judgment between the second harmonic ratio and the second harmonic content threshold, and identify the inrush current based on the first judgment result. The second judgment module is used to make a second judgment on the voltage data and the voltage threshold based on the first judgment result, and to correct the second harmonic content threshold according to the second judgment result, so as to realize the protection of the distribution network of distributed power sources.

[0055] This embodiment also provides a computer device suitable for distribution network protection of distributed power sources, including: The system includes a memory and a processor. The memory stores computer-executable instructions, and the processor executes these instructions to implement the distributed power supply network protection method proposed in the above embodiments.

[0056] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the distributed power supply network protection method proposed in the above embodiments.

[0057] The storage medium proposed in this embodiment and the distribution network protection method for distributed power sources proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0058] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computing device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0059] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A distribution network protection method for distributed power sources, characterized in that, include: Acquire current and voltage data of key nodes in the distribution network, and set the second harmonic content threshold and voltage threshold coefficient; The second harmonic ratio is calculated based on the current data, and the second harmonic ratio is compared with the second harmonic content threshold for a first judgment. The inrush current is identified based on the first judgment result. Based on the first judgment result, the voltage data and the voltage threshold are judged in a second way, and the second harmonic content threshold is corrected according to the second judgment result to realize the protection of the distribution network of distributed power sources.

2. The distribution network protection method for distributed power sources as described in claim 1, characterized in that, The first determination of the second harmonic ratio and the second harmonic content threshold includes: Calculate the fundamental amplitude and second harmonic amplitude based on the current data; The second harmonic ratio is obtained based on the mathematical relationship between the amplitude of the second harmonic and the amplitude of the fundamental wave. If the second harmonic ratio is greater than the second harmonic content threshold, it is judged as inrush current. If the second harmonic ratio is less than the second harmonic content threshold, it is judged as distributed current interference or short circuit fault, and a second judgment is made.

3. The distribution network protection method for distributed power sources as described in claim 2, characterized in that, Also includes: Set boundary parameters that characterize the allowable deviation; When the second harmonic ratio is less than the second harmonic content threshold, the deviation of the second harmonic ratio is compared with the boundary parameters. If the deviation of the second harmonic ratio is less than or equal to the boundary parameter, then the sampling period is increased. If the deviation of the second harmonic ratio is always less than or equal to the boundary parameter during the additional sampling period, then a second judgment is made. Otherwise, it is considered that the second harmonic ratio is greater than the second harmonic content threshold, and it is re-judged as an inrush current.

4. The distribution network protection method for distributed power sources as described in claim 3, characterized in that, The second determination of the voltage data and the voltage threshold includes: Obtain rated voltage data; If the voltage data is less than or equal to the product of the voltage threshold coefficient and the rated voltage data, it is judged as a short circuit fault; If the voltage data is greater than the product of the voltage threshold coefficient and the rated voltage data, it is determined to be a fluctuation in the second harmonic content caused by interference from distributed power sources.

5. The distribution network protection method for distributed power sources as described in claim 4, characterized in that, Also includes: If the voltage data is less than or equal to the product of the voltage threshold coefficient and the rated voltage data, then an additional sampling period is added; During the additional sampling period, the voltage data is continuously assessed for abnormal states. If the voltage data continuously meets the criteria for short-circuit fault during the additional sampling period, it is judged as a short-circuit fault. Otherwise, the voltage data is considered to be within the normal range.

6. The distribution network protection method for distributed power sources as described in claim 5, characterized in that, Correcting the second harmonic content threshold includes: When the second harmonic ratio is less than the second harmonic content threshold and the voltage data is greater than the product of the voltage threshold coefficient and the rated voltage data, the average of the second harmonic ratio and the second harmonic content threshold is taken to obtain the corrected second harmonic content threshold.

7. The distribution network protection method for distributed power sources as described in claim 6, characterized in that, Also includes: A time threshold is set for the corrected second harmonic content threshold; When the distribution network does not trigger the time threshold correction within the time interval, the second harmonic content threshold will be corrected to the initial second harmonic content threshold.

8. A distribution network protection system for distributed power sources, employing the distribution network protection method for distributed power sources as described in any one of claims 1-7, characterized in that, include: The data acquisition module is used to acquire current and voltage data of key nodes in the distribution network, and to set the second harmonic content threshold and voltage threshold coefficient. The first judgment module is used to calculate the second harmonic ratio based on the current data, make a first judgment between the second harmonic ratio and the second harmonic content threshold, and identify the inrush current based on the first judgment result. The second judgment module is used to make a second judgment on the voltage data and the voltage threshold based on the first judgment result, and to correct the second harmonic content threshold according to the second judgment result, so as to realize the protection of the distribution network of distributed power sources.

9. A computer device, characterized in that, include: A memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the distribution network protection method for distributed power sources according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores a computer program, which, when executed by a processor, implements the steps of the distribution network protection method for distributed power sources according to any one of claims 1 to 7.

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