Island detection method and device, photovoltaic inverter and storage medium
By collecting and processing electrical signal data from distributed generation systems, and combining disturbance signal injection and eigenvalue comparison, the problem of misjudgment in island detection is solved, thereby improving the accuracy and reliability of detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-12
- Publication Date
- 2026-04-03
AI Technical Summary
Existing island detection methods are susceptible to electromagnetic interference from the power grid and cross-interference, resulting in a high false positive rate.
Multiple electrical signal data of the distributed generation system at the common coupling point are collected within a preset time period. The electrical signal feature values are obtained through feature extraction. Combined with the injection of disturbance signals, the voltage or current feature values are compared with preset thresholds to determine whether the system is in an islanded state.
It effectively reduces the false alarm rate of island detection, ensuring the accuracy and reliability of detection, and is suitable for low-voltage, medium-voltage and high-voltage power grids.
Smart Images
Figure CN121784451A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power system testing technology, and in particular to an islanding detection method, device, photovoltaic inverter, and storage medium. Background Technology
[0002] The islanding effect refers to a situation where, when a main power grid containing distributed generation systems experiences a power outage due to a power failure, equipment maintenance, or a natural disaster, and the distributed generation system fails to detect the outage and quickly disconnect from the power grid, the system will continue to supply power to local loads, ultimately forming a self-sufficient power island uncontrolled by the power grid. The serious consequences of the islanding effect are mainly reflected in many aspects, including power quality, system equipment, and personnel safety.
[0003] Current islanding detection methods collect amplitude and frequency data of electrical signals at common coupling points. When any amplitude or frequency exceeds a preset normal threshold, an island is identified. However, the inventors have discovered that electromagnetic interference exists in power grid lines, and the coordinated operation of multiple power sources can easily generate cross-interference, leading to sudden changes in electrical signal data. Therefore, this current method is prone to misjudging islanding due to power grid disturbances, resulting in a high false alarm rate. Summary of the Invention
[0004] This invention provides an islanding detection method, device, photovoltaic inverter, and storage medium to solve the problem of high false positive rate in traditional islanding detection.
[0005] In a first aspect, embodiments of the present invention provide an islanding detection method, which is applied to a distributed generation system; the method includes: Collect multiple electrical signal data of the distributed generation system at the common coupling point within a preset time period; the preset time period includes multiple acquisition cycles; Feature extraction is performed on multiple electrical signal data to obtain electrical signal feature values; Based on the characteristic values of the electrical signal, determine whether the distributed generation system is in an islanded state.
[0006] In one possible implementation, the islanding detection method is an active islanding detection method. Before collecting multiple electrical signal data of the distributed generation system at the common coupling point within a preset time period, the method further includes: Injecting disturbance signals into distributed generation systems; Accordingly, multiple electrical signal data of the distributed generation system at the common coupling point are collected within a preset time period, including: Within a preset time period after the injection of the disturbance signal, multiple electrical signal data of the distributed generation system at the common coupling point are collected within the preset time period.
[0007] In one possible implementation, the electrical signal data includes the voltage amplitude; the electrical signal feature values include amplitude feature values. Feature extraction is performed on multiple electrical signal data to obtain the electrical signal feature values, including: Determine the absolute values of the amplitudes of multiple voltages; The voltage amplitude characteristic value is obtained by averaging the absolute values of the amplitudes of multiple voltages.
[0008] In one possible implementation, determining whether a distributed generation system is in an islanded state based on electrical signal characteristic values includes: Compare the voltage amplitude characteristic value with the preset voltage amplitude value; If the voltage amplitude characteristic value is greater than the preset voltage amplitude, the distributed generation system is determined to be in an islanded state.
[0009] In one possible implementation, the preset voltage amplitude is determined based on the maximum current of the inverter in the distributed generation system.
[0010] In one possible implementation, the disturbance signal is a disturbance signal of a preset frequency; the acquisition period is the reciprocal of the preset frequency.
[0011] In one possible implementation, the island detection method is a passive island detection method. The electrical signal data includes the instantaneous value of the current; the electrical signal feature values include the effective feature values of the current. Feature extraction is performed on multiple electrical signal data to obtain the electrical signal feature values, including: Calculate the effective current value for each acquisition cycle; The effective current characteristic value is obtained by averaging the effective current values corresponding to each acquisition cycle.
[0012] In one possible implementation, determining whether a distributed generation system is in an islanded state based on electrical signal characteristic values includes: The effective characteristic value of the current is compared with the preset effective value of the current; If the effective current characteristic value is greater than the preset effective current value, the distributed generation system is determined to be in an islanded state.
[0013] Secondly, embodiments of the present invention provide an islanding detection device, which is applied to a distributed generation system; the device includes: The acquisition module is used to acquire multiple electrical signal data of the distributed generation system at the common coupling point within a preset time period; the preset time period includes multiple acquisition cycles; The processing module is used to extract features from multiple electrical signal data to obtain electrical signal feature values; The determination module is used to determine whether the distributed generation system is in an islanded state based on the characteristic values of the electrical signal.
[0014] Thirdly, embodiments of the present invention provide a photovoltaic inverter, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the method described in the first aspect or any possible implementation of the first aspect.
[0015] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the method described in the first aspect or any possible implementation thereof.
[0016] To address the shortcomings of traditional methods, this invention collects multiple electrical signal data from a distributed generation system at a common coupling point over multiple acquisition cycles within a preset time period. This periodic acquisition method ensures a sufficiently long sampling time and guarantees the integrity and validity of the collected electrical signal data. Furthermore, considering that islanding and other factors cause continuous parameter shifts, periodic data acquisition ensures that the obtained data matches the temporal continuity of fault evolution, avoiding missed detections. Then, stability features are extracted from the multiple electrical signal data within the preset time period to highlight the target signal and suppress interference, making the obtained electrical signal feature values more closely match the detection requirements. In this case, even if interference within the power grid causes a sudden change in a single electrical parameter, the method provided in this embodiment can prevent misjudgments. Attached Figure Description
[0017] Figure 1 This is a flowchart illustrating the implementation of the island detection method provided in this embodiment of the invention. Figure 2 This is a schematic diagram of the island detection device provided in an embodiment of the present invention. Detailed Implementation
[0018] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0019] Figure 1 This is a flowchart illustrating the implementation of the island detection method provided in an embodiment of the present invention. Figure 1 As shown, this method is applied to a distributed generation system; the method includes: Step 110: Collect multiple electrical signal data of the distributed generation system at the common coupling point within a preset time period; wherein, the preset time period includes multiple acquisition cycles.
[0020] To ensure the integrity of the collected disturbance responses and avoid feature omissions caused by single-period data fragments, and to prevent missed detections due to single disturbances being canceled out by the power grid, this embodiment collects data from multiple electrical signal data at the common coupling point of the distributed generation system according to the acquisition cycle.
[0021] For example, if the power grid reference frequency is 50Hz, the acquisition period can be 20ms to match the signal period, ensuring that fixed sampling points are acquired within the acquisition period, such as 10 to 20 points per period, to fully capture peak values and zero crossings.
[0022] Step 120: Extract features from multiple electrical signal data to obtain electrical signal feature values.
[0023] The traditional method determines islanding when any amplitude or frequency exceeds a preset normal threshold. For example, if the traditional method collects a set of electrical signal data, and the amplitude of the fifth data point in this set exceeds the preset normal threshold, then the distributed generation system is determined to be in an islanded state.
[0024] However, due to interference in the power grid, especially in medium-voltage power grids, electromagnetic interference in the lines is stronger, and the cooperation of multiple power sources can easily generate cross-interference, resulting in higher interference on individual voltage data than in low-voltage power grids. If traditional methods are used for islanding detection, the misjudgment rate is high.
[0025] To address the shortcomings of traditional methods, this invention extracts features from multiple electrical signal data and comprehensively considers these multiple electrical signal data to obtain electrical signal feature values. These electrical signal feature values can offset random interference and reduce the false positive rate of island detection.
[0026] Step 130: Determine whether the distributed generation system is in an islanded state based on the electrical signal characteristic values.
[0027] Optionally, a threshold comparison method can be used to determine whether the distributed generation system is in an islanded state. That is, if the characteristic value of the electrical signal is greater than the corresponding threshold, the distributed generation system is determined to be in an islanded state.
[0028] In summary, to ensure the integrity and reliability of the collected disturbance response data, this embodiment of the invention collects multiple electrical signal data from the distributed generation system at a common coupling point within multiple collection cycles over a preset time period. To ensure that the obtained electrical signal feature values can offset random interference and reduce the false positive rate of islanding detection, this embodiment obtains electrical signal feature values by extracting features from multiple electrical signal data. Finally, a threshold comparison is used to determine whether the distributed generation system is in an islanded state. Through the above steps, even if interference within the power grid causes a sudden change in a single electrical parameter, the method provided in this embodiment can prevent false positives.
[0029] The above-mentioned steps are illustrated below through some optional embodiments: The island detection method provided in this embodiment of the invention can be either active or passive island detection. The specific implementation of the active island detection method provided in this embodiment is described below: Under active detection, before collecting multiple electrical signal data of the distributed generation system at the common coupling point within a preset time period, it is necessary to inject a disturbance signal into the distributed generation system.
[0030] Correspondingly, the collected multiple electrical signal data are the multiple electrical signal data of the distributed generation system at the common coupling point within a preset time after the injection of the disturbance signal.
[0031] In this embodiment, in order to inject disturbance signals into the distributed generation system, the AC output side of the inverter in the distributed generation system or the common coupling point between the distributed generation system and the power grid can be selected as the injection node.
[0032] Choosing different injection nodes has different advantages. For example, choosing the AC output side of the inverter as the injection node results in low transmission loss of the injected disturbance signal and requires no additional hardware support. Choosing the common coupling point as the injection node results in the injected disturbance signal being closer to the grid side, with a smaller detection blind zone. However, under this condition, additional withstand voltage equipment is required, leading to higher costs and greater complexity. Based on the comparison of the advantages and disadvantages of these two types of injection nodes, this embodiment selects the AC output side of the inverter in the distributed generation system as the injection node.
[0033] When injecting a disturbance signal, a voltage of a preset frequency can be selected as the disturbance signal. For example, the disturbance signal can be a voltage of 5Hz.
[0034] In other words, a 5Hz voltage can be selected as the disturbance signal and injected into the AC output of the inverter in the distributed generation system to achieve the purpose of injecting a disturbance signal into the distributed generation system.
[0035] Accordingly, in order to ensure that each acquisition cycle accurately matches the signal cycle and achieve distortion-free sampling and complete feature capture of the signal, the acquisition cycle can be the reciprocal of a preset frequency.
[0036] For example, if the injected disturbance signal is a 5Hz voltage, then the electrical signal data can be acquired every 50ms with a 200ms acquisition cycle, for a total of 1000ms. That is, electrical signal data from 20 points can be acquired.
[0037] In an optional embodiment, the electrical signal data includes the voltage amplitude; the electrical signal feature values include amplitude feature values; step 120, which involves feature extraction from multiple electrical signal data to obtain electrical signal feature values, may include: Determine the absolute values of the amplitudes of multiple voltages.
[0038] The voltage amplitude characteristic value is obtained by averaging the absolute values of the amplitudes of multiple voltages.
[0039] In this embodiment, the voltage amplitude can be used as the criterion. Accordingly, the electrical signal characteristic value is the voltage amplitude characteristic value determined based on the voltage amplitude. To mitigate instantaneous voltage fluctuations, clearly present continuous offsets, and accurately capture the average amplitude change caused by disturbances, the voltage amplitude characteristic value can be calculated in the following way: Since the voltage data collected at the common coupling point is itself a sinusoidal waveform, and the injected disturbance signal is also a sinusoidal waveform, the disturbance response signal, that is, within a preset time after the disturbance signal is injected, the multiple voltage data at the common coupling point of the distributed generation system exhibits periodicity, including both positive and negative half-waves. Correspondingly, the amplitudes of the multiple voltages include both positive and negative amplitudes.
[0040] If the amplitudes of each voltage are processed directly, some amplitudes may cancel each other out, resulting in the cancellation of effective signals and loss of original features. Therefore, to avoid this situation and to eliminate interference from positive and negative signs and to extract stable features, this embodiment takes the average of the absolute values of all voltage amplitudes to obtain the voltage amplitude feature values.
[0041] Besides obtaining the voltage amplitude characteristic value by averaging, other processing methods can also be used to obtain the voltage amplitude characteristic value.
[0042] In an optional embodiment, step 120, which involves feature extraction from multiple electrical signal data to obtain electrical signal feature values, may include: Remove the maximum and minimum positive amplitude values from multiple voltage positive amplitude values.
[0043] Remove the maximum and minimum negative amplitude values from multiple voltage negative amplitude values.
[0044] The voltage amplitude characteristic value is obtained by averaging the absolute values of the remaining voltage amplitudes.
[0045] In an optional embodiment, step 120, which involves feature extraction from multiple electrical signal data to obtain electrical signal feature values, may include: Remove the amplitudes of multiple voltages that are not within the historical voltage amplitude range.
[0046] The absolute values of the amplitudes of the removed voltages are averaged to obtain the characteristic values of the voltage amplitude.
[0047] In an optional embodiment, step 120, which involves feature extraction from multiple electrical signal data to obtain electrical signal feature values, may include: The peak value of each acquisition cycle is extracted from the amplitude of multiple voltages; the peak value of each acquisition cycle includes positive peak value and negative peak value.
[0048] The voltage amplitude characteristic value is obtained by averaging the absolute values of the peak values of multiple voltages.
[0049] This is because it has a stronger ability to resist extreme interference. In this embodiment, the voltage amplitude characteristic value is obtained through the peak value, which can further improve the accuracy.
[0050] This embodiment comprehensively considers the electrical signal data in each acquisition cycle within a preset time period to prevent misjudgment caused by a single value, thus ensuring the accuracy of the obtained electrical signal feature values used to characterize the current state of the distributed generation system.
[0051] Accordingly, in active islanding detection, where the electrical signal characteristic value is the voltage amplitude characteristic value, step 130, which determines whether the distributed generation system is in an islanded state based on the voltage characteristic value, may include: The amplitude characteristic value is compared with the preset voltage amplitude.
[0052] If the amplitude characteristic value is greater than the preset voltage amplitude, the distributed generation system is determined to be in an islanded state.
[0053] When the voltage characteristic value is equal to the amplitude characteristic value, the amplitude characteristic value is compared with a preset voltage amplitude value. If the amplitude characteristic value is greater than the preset voltage amplitude value, the distributed generation system is determined to be in an islanded state. If the amplitude characteristic value is less than or equal to the preset voltage amplitude value, the distributed generation system is determined not to be in an islanded state.
[0054] Because the voltage rating reference, fluctuation characteristics and power balance logic are different under different grid voltages, the preset voltage amplitude determined by experience or historical values in traditional methods is inaccurate, which will also lead to low accuracy of islanding detection.
[0055] Considering that in distributed generation systems, the inverter's maximum current corresponds to the system's maximum output power, determining the upper limit of voltage amplitude deviation during islanding, i.e., power imbalance is most significant and voltage deviation is greatest at maximum current. Therefore, the preset voltage amplitude can be determined based on the inverter's maximum current in the distributed generation system. In this way, the determined preset voltage amplitude can cover all operating conditions, avoiding both overly broad thresholds leading to missed detections at low currents and overly strict thresholds causing false detections at high currents. This ensures the preset value adapts to extreme system conditions, balancing detection sensitivity and interference resistance.
[0056] In active islanding detection, in addition to using the voltage amplitude as the basis for judging whether an islanding state exists, other data can also be used.
[0057] In an optional embodiment, the electrical signal data may include the frequency of the voltage; the electrical signal feature values include voltage frequency feature values; step 120, which involves feature extraction from multiple electrical signal data to obtain electrical signal feature values, may include: Calculate the difference between the voltage frequency and the reference voltage frequency within each sampling period within the preset time period to obtain the voltage frequency difference corresponding to each sampling period.
[0058] The voltage frequency characteristic value is obtained by averaging the voltage frequency difference corresponding to each acquisition cycle.
[0059] Optionally, the frequency of the voltage can also be used as a criterion. Accordingly, the characteristic value of the electrical signal is the voltage frequency characteristic value determined based on the frequency of the voltage.
[0060] The voltage frequency characteristic value can be calculated in the following way: For the voltage data of each acquisition cycle, the instantaneous frequency is calculated by the zero-crossing detection method or the Fourier transform method, and the difference is obtained by comparing it with the reference frequency, such as 50Hz, to obtain the voltage frequency difference of a single cycle.
[0061] The voltage frequency difference of all acquisition cycles is arithmetically averaged to obtain the voltage frequency characteristic value, which is used to compare with a preset threshold to determine islands.
[0062] Accordingly, when the characteristic value of the electrical signal is the voltage frequency characteristic value, step 130, which determines whether the distributed generation system is in an islanded state based on the electrical signal characteristic value, may include: The voltage frequency characteristic value is compared with the preset voltage frequency difference value.
[0063] If the voltage frequency characteristic value is greater than the preset voltage frequency difference, the distributed generation system is determined to be in an islanded state.
[0064] Similar to the case where the electrical signal characteristic value is the voltage amplitude characteristic value, when the electrical signal characteristic value is the voltage frequency characteristic value, if the voltage frequency characteristic value is greater than a preset voltage frequency difference, the distributed generation system is determined to be in an islanded state. If the voltage frequency characteristic value is less than or equal to the preset voltage frequency difference, the distributed generation system is determined not to be in an islanded state.
[0065] In summary, this embodiment of the invention collects multiple voltage data points at the common coupling point of a distributed generation system within multiple acquisition cycles over a preset time period after the injection of a disturbance signal, ensuring the validity of the collected data. Then, the multiple electrical signal data are processed accordingly, such as by averaging, to highlight the target signal and suppress interference, making the obtained voltage characteristic values more closely match the detection requirements. In this case, even if interference within the medium-voltage power grid causes a sudden change in a single electrical parameter, the method provided in this embodiment can prevent misjudgment.
[0066] The above embodiments describe the specific implementation of active island detection. The following embodiments illustrate the passive island detection method. For details not fully explained in the passive island detection method, please refer to the description in the active detection method. The following describes the specific implementation of the passive island detection method provided in this embodiment: In an optional embodiment, if the island detection method is a passive detection method, the electrical signal data includes the instantaneous value of the current; the electrical signal feature values include the effective feature values of the current. In step 120, feature extraction is performed on multiple electrical signal data to obtain the electrical signal feature values, including: Calculate the effective current value for each acquisition cycle.
[0067] The effective current characteristic value is obtained by averaging the effective current values corresponding to each acquisition cycle.
[0068] Similarly, to prevent the instantaneous values of the collected current from being canceled out during the calculation process, this embodiment of the invention obtains the effective characteristic value of the current based on the effective value of the current. The calculation of the effective value of the current is completely independent of whether the current value is positive or negative, and this value ensures that no data is missed or eliminated.
[0069] Then, to mitigate fluctuations caused by the power grid itself and prevent misjudgments, the effective current value is averaged to obtain the effective current characteristic value. Of course, besides averaging, other methods can also be used to obtain the effective current characteristic value; for details, please refer to the relevant embodiments for obtaining voltage amplitude characteristic values in active islanding detection.
[0070] When the characteristic value of the electrical signal is the effective characteristic value of the current, step 130, which determines whether the distributed generation system is in an islanded state based on the characteristic value of the electrical signal, may include: The effective characteristic value of the current is compared with the preset effective value of the current.
[0071] If the effective current characteristic value is greater than the preset effective current value, the distributed generation system is determined to be in an islanded state.
[0072] In this embodiment, the determination of whether the distributed generation system is in an islanded state is also performed using a threshold comparison method. If the effective current characteristic value is greater than the preset effective current value, the distributed generation system is determined to be in an islanded state; if the effective current characteristic value is not greater than the preset effective current value, the distributed generation system is determined not to be in an islanded state.
[0073] Considering that the inverter's maximum output current is directly anchored to the maximum output power boundary of the distributed generation system, and there is no grid power buffer in islanded mode, if the load power suddenly drops, the inverter will limit its output current, and the effective value of the current will be lower than the normal range; if the load power suddenly increases, the effective value of the current will exceed the rated value, approaching or exceeding the reasonable threshold directly corresponding to the maximum output current. Therefore, the preset effective value of the current can also be determined based on the inverter's maximum output current. This method can accurately cover extreme power imbalance scenarios in islanded mode, avoid the threshold from being out of sync with the actual output capacity of the system, and eliminate the interference of normal load fluctuations when connected to the grid.
[0074] In addition to the electrical signal data listed in the relevant embodiments, judgments can also be made using phase, rate of change of frequency, total harmonic distortion, characteristic harmonic amplitude, active power, reactive power, etc. The judgment methods can be found in the relevant embodiments.
[0075] In summary, the method provided by this invention can improve the accuracy of islanding detection and can be applied to low-voltage, medium-voltage, and high-voltage power grids, especially medium-voltage power grids. Furthermore, to ensure the integrity and reliability of the collected disturbance response data, the collected electrical signal data consists of multiple electrical signal data from the distributed generation system at the common coupling point within multiple acquisition cycles over a preset time period. To ensure that the electrical signal feature values can offset random interference and reduce the false alarm rate of islanding detection, this embodiment obtains the electrical signal feature values by taking the stability characteristics of multiple electrical signal data. Moreover, considering that the thresholds traditionally used for comparison are set based on power grid parameters and historical values, the fact that thresholds are not universally applicable across different voltages is overlooked. For example, if the comparison thresholds for 400V and 800V power grids are determined using the same method, this threshold can effectively detect islanding under a 400V power grid, but may not be accurate under 800V. This is because traditional comparison threshold settings ignore the nature of islanding. In islanding, the grid is disconnected, and the distributed generation system and the local load directly form a closed energy loop, resulting in power imbalance. That is, the output power of the distributed generation system is not equal to the power of the local load, which will directly cause the current to exceed the normal range of the inverter's maximum output current constraint. Therefore, the comparison threshold in this embodiment is determined based on the inverter's maximum output current, which can avoid misjudgment caused by inaccurate threshold settings.
[0076] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.
[0077] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.
[0078] Figure 2 A schematic diagram of the island detection device provided in an embodiment of the present invention is shown. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below: like Figure 2 As shown, the islanding detection device 2 is applied to a distributed generation system; the islanding detection device 2 includes: The acquisition module 21 is used to acquire multiple electrical signal data of the distributed generation system at the common coupling point within a preset time period; wherein the preset time period includes multiple acquisition cycles; Processing module 22 is used to extract features from multiple electrical signal data to obtain electrical signal feature values; The determination module 23 is used to determine whether the distributed generation system is in an islanded state based on the characteristic values of the electrical signal.
[0079] In one possible implementation, if the islanding detection method is an active detection method, the islanding detection device 2 further includes an injection module 24, which is used to inject disturbance signals into the distributed generation system. Correspondingly, the acquisition module 21 is specifically used for: Within a preset time period after the injection of the disturbance signal, multiple electrical signal data of the distributed generation system at the common coupling point are collected within the preset time period.
[0080] In one possible implementation, the electrical signal data includes the voltage amplitude; the electrical signal characteristic values include amplitude characteristic values; and the processing module 22 is specifically used for: Determine the absolute values of the amplitudes of multiple voltages; The voltage amplitude characteristic value is obtained by averaging the absolute values of the amplitudes of multiple voltages.
[0081] In one possible implementation, the determination module 23 is specifically used for: Compare the voltage amplitude characteristic value with the preset voltage amplitude value; If the voltage amplitude characteristic value is greater than the preset voltage amplitude, the distributed generation system is determined to be in an islanded state.
[0082] In one possible implementation, the preset voltage amplitude is determined based on the maximum current of the inverter in the distributed generation system; the disturbance signal is a disturbance signal of a preset frequency; and the acquisition period is the reciprocal of the preset frequency.
[0083] In one possible implementation, if the island detection method is a passive detection method, the electrical signal data includes the instantaneous value of the current; the electrical signal characteristic values include the effective characteristic values of the current; the processing module 22 is specifically used for: Calculate the effective current value for each acquisition cycle; The effective current characteristic value is obtained by averaging the effective current values corresponding to each acquisition cycle.
[0084] In one possible implementation, the determination module 23 is specifically used for: The effective characteristic value of the current is compared with the preset effective value of the current; If the effective current characteristic value is greater than the preset effective current value, the distributed generation system is determined to be in an islanded state.
[0085] This invention also provides a photovoltaic inverter, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the method described in the above method embodiments.
[0086] This invention also provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the method described in the first aspect or any possible implementation thereof.
[0087] Computer-executable instructions include computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. Computer-readable storage media can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.
[0088] In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not detailed or described in a particular embodiment can be referred to in the relevant descriptions of other embodiments. Unless otherwise specified or in conflict with logic, the terminology and / or descriptions between different embodiments are consistent and can be referenced interchangeably. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.
[0089] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.
Claims
1. An island detection method, characterized in that, Applied to distributed generation systems; the method includes: Collect multiple electrical signal data of the distributed generation system at the common coupling point within a preset time period; wherein, the preset time period includes multiple acquisition cycles; Feature extraction is performed on the multiple electrical signal data to obtain electrical signal feature values; Based on the electrical signal characteristic values, determine whether the distributed generation system is in an islanded state.
2. The island detection method according to claim 1, characterized in that, The islanding detection method is an active islanding detection method. Before collecting multiple electrical signal data of the distributed generation system at a common coupling point within the preset acquisition time period, the method further includes: Injecting a disturbance signal into the distributed generation system; Accordingly, the acquisition of multiple electrical signal data of the distributed generation system at the common coupling point within a preset time period includes: Within a preset time period after the disturbance signal is injected, multiple electrical signal data of the distributed generation system at the common coupling point are collected within the preset time period.
3. The island detection method according to claim 2, characterized in that, The electrical signal data includes the voltage amplitude; The electrical signal feature values include voltage amplitude feature values. The step of extracting features from the plurality of electrical signal data to obtain the electrical signal feature values includes: Determine the absolute values of the amplitudes of multiple voltages; The voltage amplitude characteristic value is obtained by averaging the absolute values of the amplitudes of multiple voltages.
4. The island detection method according to claim 3, characterized in that, The step of determining whether the distributed generation system is in an islanded state based on the electrical signal characteristic value includes: The voltage amplitude characteristic value is compared with the preset voltage amplitude value; If the voltage amplitude characteristic value is greater than the preset voltage amplitude value, the distributed generation system is determined to be in an islanded state.
5. The island detection method according to claim 4, characterized in that, The preset voltage amplitude is determined based on the maximum current of the inverter in the distributed generation system; the disturbance signal is a disturbance signal of a preset frequency; and the acquisition period is the reciprocal of the preset frequency.
6. The island detection method according to claim 1, characterized in that, The islanding detection method is a passive islanding detection method, and the electrical signal data includes the instantaneous value of the current; The electrical signal feature values include effective current feature values; the feature extraction from the plurality of electrical signal data to obtain electrical signal feature values includes: Calculate the effective current value for each acquisition cycle; The effective current characteristic value is obtained by averaging the effective current values corresponding to each acquisition cycle.
7. The island detection method according to claim 6, characterized in that, The step of determining whether the distributed generation system is in an islanded state based on the electrical signal characteristic value includes: The effective characteristic value of the current is compared with the preset effective value of the current; If the effective current characteristic value is greater than the preset effective current value, the distributed generation system is determined to be in an islanded state.
8. An island detection device, characterized in that, The device, applied to a distributed generation system, includes: The acquisition module is used to acquire multiple electrical signal data of the distributed generation system at a common coupling point within a preset time period; wherein, the preset time period includes multiple acquisition cycles; The processing module is used to extract features from the multiple electrical signal data to obtain electrical signal feature values; The determination module is used to determine whether the distributed generation system is in an islanded state based on the characteristic values of the electrical signal.
9. A photovoltaic inverter, characterized in that, It includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the method as described in any one of claims 1 to 7.
10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions that, when executed by a processor, implement the method as described in any one of claims 1 to 7.