Fault feature detection method for photovoltaic flexible direct current transmission system

Abstract

The invention provides a photovoltaic flexible direct current sending-out system fault feature detection method, which comprises the following steps: in a photovoltaic flexible direct current sending-out system, collecting a sending end alternating current voltage amplitude, sending end alternating current active power, a direct current voltage amplitude, direct current power, a receiving end alternating current voltage amplitude and receiving end alternating current active power; according to the sending-end alternating-current voltage amplitude, the sending-end alternating-current active power, the direct-current voltage amplitude and the direct-current power, sending-end alternating-current fault detection is carried out on the photovoltaic flexible direct-current sending-out system; according to the receiving-end alternating-current voltage amplitude, the receiving-end alternating-current active power and the direct-current voltage amplitude, receiving-end alternating-current fault detection is carried out on the photovoltaic flexible direct-current sending-out system; and according to the DC voltage amplitude and the DC power, DC line fault detection is carried out on the photovoltaic flexible DC sending-out system. According to the method, the change of each key electrical quantity of the system can be comprehensively monitored, and different types of faults can be accurately identified.

Description

Technical Field

[0001] This application relates to the technical field of flexible DC power transmission, and particularly to a method for detecting fault characteristics of a photovoltaic system transmitted through a flexible DC system. Background Art

[0002] Flexible DC power transmission technology has become an important solution for long-distance transmission of new energy due to its advantages such as rapid power adjustment, suppression of new energy power fluctuations, and long-distance transmission. However, when a large-scale photovoltaic system is transmitted through a flexible DC system, system faults will not only affect the effective consumption of photovoltaic power, but may also seriously threaten the safety and stable operation of the power system in severe cases. Therefore, it is of great significance to study the fault ride-through characteristics of a large-scale photovoltaic system transmitted through a flexible DC system and improve its fault ride-through ability.

[0003] The fault types of DC systems mainly include sending-end AC faults, DC line faults, and receiving-end AC faults. Due to the interaction and coupling between the sending and receiving ends of the DC system, any fault will cause changes in the dynamic characteristics of the system. Fault points at different positions will result in both similarities and differences in system responses, so the control measures taken are also different. Accurately identifying the fault point is the key to formulating an effective fault ride-through control strategy. However, existing fault ride-through technologies usually rely on a single electrical quantity to judge fault characteristics, and this method has the risk of inaccurate fault characteristic identification, which affects the improvement of fault ride-through ability and the guarantee of system stability. Summary of the Invention

[0004] The purpose of this application aims to at least solve one of the above technical defects, especially the technical defect of the risk of inaccurate fault characteristic identification in the prior art.

[0005] In a first aspect, this application provides a method for detecting fault characteristics of a photovoltaic system transmitted through a flexible DC system, and the method includes:

[0006] In a photovoltaic system transmitted through a flexible DC system, collect the sending-end AC voltage amplitude, sending-end AC active power, DC voltage amplitude, DC power, receiving-end AC voltage amplitude, and receiving-end AC active power;

[0007] According to the sending-end AC voltage amplitude, sending-end AC active power, DC voltage amplitude, and DC power, perform sending-end AC fault detection on the photovoltaic system transmitted through the flexible DC system;

[0008] According to the receiving-end AC voltage amplitude, receiving-end AC active power, and DC voltage amplitude, perform receiving-end AC fault detection on the photovoltaic system transmitted through the flexible DC system;

[0009] According to the DC voltage amplitude and DC power, perform DC line fault detection on the photovoltaic system transmitted through the flexible DC system.

[0010] In one embodiment, the steps of performing a sending - end AC fault detection on a photovoltaic flexible DC transmission system according to the sending - end AC voltage amplitude, the sending - end AC active power, and the DC voltage amplitude include:

[0011] If the sending - end AC voltage amplitude is less than a first preset threshold, the sending - end AC active power is less than a second preset threshold, and the DC voltage amplitude is less than a third preset threshold, it is determined that there is a sending - end AC fault in the photovoltaic flexible DC transmission system;

[0012] Wherein, in the photovoltaic flexible DC transmission system, the first preset threshold is a first preset multiple of the sending - end AC voltage rated value, the second preset threshold is a second preset multiple of the previous - moment sending - end AC active power value, and the third preset threshold is a third preset multiple of the DC voltage rated value.

[0013] In one embodiment, the steps of performing a sending - end AC fault detection on a photovoltaic flexible DC transmission system according to the sending - end AC voltage amplitude, the sending - end AC active power, the DC voltage amplitude, and the DC power include:

[0014] If the receiving - end AC voltage amplitude is less than a fourth preset threshold, the receiving - end AC active power is less than a fifth preset threshold, the DC voltage amplitude is greater than a sixth preset threshold, and the DC power is greater than a seventh preset threshold, it is determined that there is a receiving - end AC fault in the photovoltaic flexible DC transmission system;

[0015] Wherein, in the photovoltaic flexible DC transmission system, the fourth preset threshold is a fourth preset multiple of the receiving - end AC voltage rated value, the fifth preset threshold is a fifth preset multiple of the previous - moment receiving - end AC active power value, the sixth preset threshold is a sixth preset multiple of the DC voltage rated value, and the seventh preset threshold is a seventh preset multiple of the previous - moment DC power.

[0016] In one embodiment, the steps of performing a DC line fault detection on a photovoltaic flexible DC transmission system according to the DC voltage amplitude and the DC power include:

[0017] If the DC voltage amplitude is greater than an eighth preset threshold and the DC power is less than a ninth preset threshold, it is determined that there is a DC line fault in the photovoltaic flexible DC transmission system;

[0018] Wherein, in the photovoltaic flexible DC transmission system, the eighth preset threshold is an eighth preset multiple of the DC voltage rated value, and the ninth preset threshold is a ninth preset multiple of the previous - moment DC power value.

[0019] In a second aspect, the present application provides a fault feature detection device for a photovoltaic flexible DC transmission system. The device includes:

[0020] A data acquisition module, which is used to collect the sending - end AC voltage amplitude, sending - end AC active power, DC voltage amplitude, DC power, receiving - end AC voltage amplitude, and receiving - end AC active power in a photovoltaic flexible DC transmission system;

[0021] A sending - end AC fault detection module, which is used to detect the sending - end AC fault of the photovoltaic flexible DC transmission system according to the sending - end AC voltage amplitude, sending - end AC active power, DC voltage amplitude, and DC power;

[0022] A receiving - end AC fault detection module, which is used to detect the receiving - end AC fault of the photovoltaic flexible DC transmission system according to the receiving - end AC voltage amplitude, receiving - end AC active power, and DC voltage amplitude;

[0023] A DC line fault detection module, which is used to detect the DC line fault of the photovoltaic flexible DC transmission system according to the DC voltage amplitude and DC power.

[0024] In one embodiment, the sending - end AC fault detection module includes:

[0025] A sending - end AC fault detection unit, which is used to determine that there is a sending - end AC fault in the photovoltaic flexible DC transmission system if the sending - end AC voltage amplitude is less than a first preset threshold, the sending - end AC active power is less than a second preset threshold, and the DC voltage amplitude is less than a third preset threshold;

[0026] Wherein, in the photovoltaic flexible DC transmission system, the first preset threshold is a first preset multiple of the sending - end AC voltage rated value, the second preset threshold is a second preset multiple of the previous moment's sending - end AC active power value, and the third preset threshold is a third preset multiple of the DC voltage rated value.

[0027] In one embodiment, the receiving - end AC fault detection module includes:

[0028] A receiving - end AC fault detection unit, which is used to determine that there is a receiving - end AC fault in the photovoltaic flexible DC transmission system if the receiving - end AC voltage amplitude is less than a fourth preset threshold, the receiving - end AC active power is less than a fifth preset threshold, the DC voltage amplitude is greater than a sixth preset threshold, and the DC power is greater than a seventh preset threshold;

[0029] Wherein, in the photovoltaic flexible DC transmission system, the fourth preset threshold is a fourth preset multiple of the receiving - end AC voltage rated value, the fifth preset threshold is a fifth preset multiple of the previous moment's receiving - end AC active power value, the sixth preset threshold is a sixth preset multiple of the DC voltage rated value, and the seventh preset threshold is a seventh preset multiple of the previous moment's DC power.

[0030] In one embodiment, the DC line fault detection module includes:

[0031] A DC line fault detection unit is used to determine that there is a DC line fault in the flexible DC transmission system for PV power generation if the DC voltage amplitude is greater than the eighth preset threshold and the DC power is less than the ninth preset threshold.

[0032] Wherein, in the flexible DC transmission system for PV power generation, the eighth preset threshold is the eighth preset multiple of the rated DC voltage, and the ninth preset threshold is the ninth preset multiple of the previous moment's DC power value.

[0033] In a third aspect, the present application provides a storage medium: computer-readable instructions are stored in the storage medium, and when the computer-readable instructions are executed by one or more processors, the one or more processors are caused to execute the steps of any one of the above-mentioned embodiments of the fault feature detection method for the flexible DC transmission system for PV power generation.

[0034] In a fourth aspect, the present application provides a computer device, including: one or more processors, and a memory;

[0035] Computer-readable instructions are stored in the memory, and when the computer-readable instructions are executed by one or more processors, the steps of any one of the above-mentioned embodiments of the fault feature detection method for the flexible DC transmission system for PV power generation are executed.

[0036] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0037] The fault feature detection method for the flexible DC transmission system for PV power generation provided by the present application collects multiple electrical quantities at the sending end and the receiving end, such as AC voltage amplitude, AC active power, DC voltage amplitude, DC power, etc., and respectively detects the sending-end AC fault, the receiving-end AC fault, and the DC line fault. This method simultaneously collects multiple electrical quantities such as the sending-end AC voltage amplitude, the sending-end AC active power, the DC voltage amplitude, the DC power, the receiving-end AC voltage amplitude, and the receiving-end AC active power, and these data respectively correspond to different operating states of the system. By considering multiple variables simultaneously, the dynamic changes of the system can be more comprehensively reflected, avoiding misjudgment caused by some interference factors for a single electrical quantity. In addition, the fault types are further divided into the sending-end AC fault, the receiving-end AC fault, and the DC line fault, and independent detections are performed according to different electrical quantities. This can ensure that each fault type can obtain accurate diagnosis, improve the accuracy of fault detection, and avoid misclassification caused by the cross-influence of faults in traditional methods. In this way, the accuracy and stability of fault feature recognition are improved, thereby enhancing the fault ride-through ability of the flexible DC transmission system for PV power generation and ensuring the effective consumption of new energy and the safe operation of the power system. Description of the Drawings

[0038] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 Schematic flow chart of the fault feature detection method for the photovoltaic flexible DC transmission system provided by the embodiment of the present application;

[0040] Figure 2 Example diagram of the fault feature detection method for the photovoltaic flexible DC transmission system provided by the embodiment of the present application;

[0041] Figure 3 Schematic structural diagram of the fault feature detection device for the photovoltaic flexible DC transmission system provided by the embodiment of the present application;

[0042] Figure 4 Internal structural diagram of the computer device provided by the embodiment of the present application. Detailed implementation manners

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0044] The present application provides a fault feature detection method for a photovoltaic flexible DC transmission system. The following embodiments are described by taking the application of this method to a computer device as an example. It can be understood that the computer device can be various devices with data processing functions, and can be, but not limited to, a single server, a server cluster, a personal laptop, a desktop computer, etc. As Figure 1 shown, the method may include the following steps:

[0045] S101: In the photovoltaic flexible DC transmission system, collect the sending-end AC voltage amplitude, sending-end AC active power, DC voltage amplitude, DC power, receiving-end AC voltage amplitude, and receiving-end AC active power.

[0046] Among them, the amplitude of the sending - end AC voltage refers to the instantaneous maximum value of the sending - end AC voltage of the PV flexible DC transmission system, which is used to reflect the magnitude and variation of the sending - end voltage waveform. The sending - end AC active power refers to the active power transmitted in the sending - end AC line of the PV flexible DC transmission system, indicating the ability of the sending - end to convert electrical energy into useful work. The DC voltage amplitude refers to the instantaneous maximum value of the DC transmission line voltage in the PV flexible DC transmission system, reflecting the voltage level and stability of the DC transmission line. The DC power refers to the effective output power of electrical energy in the DC transmission line of the PV flexible DC transmission system. The receiving - end AC voltage amplitude refers to the instantaneous maximum value of the receiving - end AC voltage of the PV flexible DC transmission system, which is used to reflect the fluctuation characteristics of the receiving - end voltage. The receiving - end AC active power refers to the active power transmitted in the receiving - end AC line of the PV flexible DC transmission system, indicating the effective electrical energy obtained by the receiving - end from the transmission line.

[0047] In this step, in the PV flexible DC transmission system, the task of collecting these electrical quantities can be completed by hardware devices such as voltage transformers, current transformers, and power meters. The computer device obtains real - time electrical data from the sensors at the sending - end and the receiving - end through a dedicated signal acquisition module. Specifically, the voltage and current signals can be converted into digital signals through analog - to - digital conversion (ADC) technology at regular intervals for subsequent processing and analysis. After being collected, these signals are transmitted to the central data processing unit through a high - speed communication network such as industrial Ethernet and optical fiber transmission.

[0048] It can be understood that in the PV flexible DC transmission system, collecting multiple electrical quantities at the sending - end and the receiving - end and performing real - time processing on them can comprehensively monitor the operation status of the system and promptly detect problems. By collecting voltage amplitude and power data, the stability of power transmission, the change of load, and the effectiveness of DC transmission can be accurately reflected.

[0049] S102: Detect the sending - end AC fault of the PV flexible DC transmission system according to the amplitude of the sending - end AC voltage, the sending - end AC active power, the DC voltage amplitude, and the DC power.

[0050] In this step, after data collection, the signal can be pre - processed, for example, applying a filter to remove noise and high - frequency interference to ensure the accuracy of the signal. Next, a fault detection algorithm can be executed according to the changes in the amplitude of the sending - end AC voltage and the sending - end AC active power.

[0051] For example, when the amplitude of the sending - end AC voltage fluctuates too high or too low, or the sending - end AC active power deviates from the normal range, it can be judged that faults such as voltage instability, load overload, or power abnormality may have occurred at the sending end. At the same time, by analyzing the DC voltage amplitude and DC power, it is also possible to check for abnormalities in the DC power output, thereby identifying possible fault sources. Finally, a fault diagnosis report is output according to the detection results.

[0052] It can be understood that by performing sending - end AC fault detection on the sending - end AC voltage amplitude, sending - end AC active power, DC voltage amplitude, and DC power, the operating state of the PV - based flexible DC transmission system can be comprehensively monitored, and the possible fault characteristics at the sending end can be accurately identified.

[0053] S103: Perform receiving - end AC fault detection on the PV - based flexible DC transmission system according to the receiving - end AC voltage amplitude, receiving - end AC active power, and DC voltage amplitude.

[0054] In this step, the collected data can be filtered, denoised, and normalized to eliminate measurement errors and interference signals. Based on the pre - processed data, algorithms can be used to dynamically monitor the changing trends of the receiving - end AC voltage amplitude and active power, and at the same time, combined with the change of the DC voltage amplitude, the operating state of the system can be analyzed. Specific methods include threshold detection, signal spectrum analysis, or fault mode recognition using machine - learning models. By comprehensively analyzing the above - mentioned characteristic data, it is judged whether there are voltage offsets, power outages, or other abnormal phenomena at the receiving end. If an abnormal signal beyond the preset threshold range is detected, it is determined that an AC fault may have occurred at the receiving end.

[0055] It can be understood that receiving - end AC fault detection can comprehensively capture the operating state of the receiving end by collecting the receiving - end AC voltage amplitude, AC active power, and DC voltage amplitude, and use multi - dimensional data characteristics to achieve accurate fault identification and rapid judgment. Furthermore, it can real - time detect abnormal problems in the receiving - end power grid, locate potential fault points, and prevent the expansion of faults. At the same time, combined with the dynamic analysis of the DC voltage, the impact of the fault on the entire transmission system can be evaluated, further improving the reliability of fault detection.

[0056] S104: Perform DC line fault detection on the PV - based flexible DC transmission system according to the DC voltage amplitude and DC power.

[0057] In this step, the collected data can be filtered, denoised, and outlier processed to ensure the accuracy and stability of data input. For example, for the instantaneous interference in the DC voltage signal, a low-pass filtering method is used to remove the noise. Then, the dynamic change trends of the DC voltage and power can be analyzed using algorithms. By setting the threshold values within the normal operating range, the voltage fluctuations or power deviations can be monitored. For example, if the voltage drops below a specific threshold and is accompanied by a sudden drop in power, it may indicate a short circuit in the line. Based on the results of the feature analysis, the fault type and location can be determined. For example, an expert system or a machine learning model can be combined to perform pattern matching on the fault data to identify specific line abnormalities such as short circuits, ground faults, or broken wires.

[0058] It can be understood that the DC power transmission system is usually responsible for high-capacity and long-distance power transmission, and its faults may lead to a decline in system stability or even a large-scale power outage. Based on this, it is necessary to detect faults in the DC line. By collecting and analyzing the real-time DC voltage amplitude and DC power, faults in the DC transmission line can be quickly detected, the abnormal area can be located, and the fault type can be identified.

[0059] In the above embodiment, by collecting multiple electrical quantities at the sending end and the receiving end, such as AC voltage amplitude, AC active power, DC voltage amplitude, DC power, etc., and detecting the sending-end AC fault, receiving-end AC fault, and DC line fault respectively. This method simultaneously collects multiple electrical quantities such as the sending-end AC voltage amplitude, sending-end AC active power, DC voltage amplitude, DC power, receiving-end AC voltage amplitude, and receiving-end AC active power. These data respectively correspond to different operating states of the system. By considering multiple variables simultaneously, the dynamic changes of the system can be more comprehensively reflected, avoiding misjudgment caused by some interference factors for a single electrical quantity. In addition, the fault types are further divided into sending-end AC faults, receiving-end AC faults, and DC line faults, and independent detections are performed according to different electrical quantities. This can ensure that each fault type can obtain accurate diagnosis, improve the accuracy of fault detection, and avoid misclassification caused by the cross-influence of faults in traditional methods. In this way, the accuracy and stability of fault feature recognition are improved, thereby enhancing the fault ride-through ability of the PV system with flexible DC output, ensuring the effective consumption of new energy, and the safe operation of the power system.

[0060] In one embodiment, the steps of detecting the sending-end AC fault of the PV system with flexible DC output according to the sending-end AC voltage amplitude, sending-end AC active power, and DC voltage amplitude include:

[0061] If the sending-end AC voltage amplitude is less than the first preset threshold, the sending-end AC active power is less than the second preset threshold, and the DC voltage amplitude is less than the third preset threshold, it is determined that there is a sending-end AC fault in the PV system with flexible DC output;

[0062] Among them, in the photovoltaic flexible DC transmission system, the first preset threshold is the first preset multiple of the rated value of the sending-end AC voltage, the second preset threshold is the second preset multiple of the sending-end AC active power value at the previous moment, and the third preset threshold is the third preset multiple of the rated value of the DC voltage. It can be understood that the thresholds are set according to experience, taking into account the normal deviation and fluctuation range of the power system.

[0063] Among them, the first preset threshold is the reference standard for the amplitude of the sending-end AC voltage, used to judge whether the voltage of the sending-end power grid is normal, and this threshold is the first preset multiple of the rated value of the sending-end AC voltage. The second preset threshold is the reference standard for the sending-end AC active power, used to judge whether the power of the sending-end power grid is within the normal range, and this threshold is the second preset multiple of the sending-end AC active power value at the previous moment. The third preset threshold is the reference standard for the amplitude of the DC voltage, used to judge whether the voltage of the DC transmission line is normal, and this threshold is the third preset multiple of the rated value of the DC voltage.

[0064] Specifically, first, according to the preset parameters, three thresholds can be determined: the first preset threshold is the first preset multiple of the rated value of the sending-end AC voltage, the second preset threshold is the second preset multiple of the sending-end AC active power value at the previous moment, and the third preset threshold is the third preset multiple of the rated value of the DC voltage. Then, these thresholds are stored and updated in real time for dynamic comparison. Next, the collected real-time data is compared with the set thresholds. If the amplitude of the sending-end AC voltage is less than the first preset threshold, the sending-end AC active power is less than the second preset threshold, and the amplitude of the DC voltage is less than the third preset threshold, it is determined that there is a sending-end AC fault.

[0065] In an example, assume that the rated value of the sending-end AC voltage of the photovoltaic flexible DC transmission system is 220V, the sending-end AC active power value at the previous moment is 50kW, and the rated value of the DC voltage is 500V; at this time, the first preset threshold is 0.9 times the rated value of the sending-end AC voltage, that is, 198V; the second preset threshold is 0.9 times the sending-end AC active power value at the previous moment, that is, 45kW; the third preset threshold is 0.95 times the rated value of the DC voltage, that is, 475V. Assume that the currently collected data is: the amplitude of the sending-end AC voltage is 185V, the sending-end AC active power is 40kW, and the amplitude of the DC voltage is 460V. Since the currently measured amplitude of the sending-end AC voltage 185V is less than the first preset threshold 198V, the sending-end AC active power 40kW is less than the second preset threshold 45kW, and the amplitude of the DC voltage 460V is less than the third preset threshold 475V, it can be judged that there is a sending-end AC fault.

[0066] In this embodiment, by monitoring the amplitude of the sending - end AC voltage, the sending - end AC active power, and the DC voltage amplitude in real - time and comparing them with the threshold values, it is possible to quickly determine whether there is a sending - end AC fault. Through this method, faults can be detected in a timely manner and their expansion can be prevented, thus effectively ensuring the safe and stable operation of the system and avoiding major damages.

[0067] In one embodiment, the steps of performing sending - end AC fault detection on a photovoltaic flexible DC transmission system according to the amplitude of the sending - end AC voltage, the sending - end AC active power, the DC voltage amplitude, and the DC power include:

[0068] If the amplitude of the receiving - end AC voltage is less than the fourth preset threshold, the receiving - end AC active power is less than the fifth preset threshold, the DC voltage amplitude is greater than the sixth preset threshold, and the DC power is greater than the seventh preset threshold, it is determined that there is a receiving - end AC fault in the photovoltaic flexible DC transmission system;

[0069] Among them, in the photovoltaic flexible DC transmission system, the fourth preset threshold is the third preset multiple of the rated value of the receiving - end AC voltage, the fifth preset threshold is the value of the receiving - end AC active power at the previous moment, the sixth preset threshold is the fourth preset multiple of the rated value of the DC voltage, and the seventh preset threshold is the fifth preset multiple of the DC power at the previous moment.

[0070] Among them, the fourth preset threshold is a standard value for judging whether the amplitude of the receiving - end AC voltage is normal, and is set as a certain preset multiple of the rated value of the receiving - end AC voltage. The fifth preset threshold is a standard value for judging whether the receiving - end AC active power is normal, and is set as a certain multiple of the value of the receiving - end AC active power at the previous moment. The sixth preset threshold is a standard value for judging whether the DC voltage amplitude is normal, and is usually set as a certain preset multiple of the rated value of the DC voltage. The seventh preset threshold is a standard value for judging whether the DC power is normal, and is usually set as a certain multiple of the value of the DC power at the previous moment. It can be understood that the threshold values are set according to experience, taking into account the normal deviation and fluctuation range of the power system.

[0071] Specifically, the amplitude of the receiving - end AC voltage, the receiving - end active power, the DC voltage amplitude, and the DC power value are respectively compared with their corresponding threshold values, that is, it is judged whether the amplitude of the receiving - end AC voltage is less than the fourth preset threshold, whether the receiving - end AC active power is less than the fifth preset threshold, whether the DC voltage amplitude is greater than the sixth preset threshold, and whether the DC power is greater than the seventh preset threshold. After all conditions have completed the threshold comparison, by synthesizing this information, it is judged whether each index simultaneously meets the preset fault conditions. If the receiving - end AC voltage and the receiving - end AC active power are lower than the corresponding threshold values, while the DC voltage and the DC power are respectively greater than the corresponding threshold values, then the occurrence of the receiving - end AC fault will be confirmed.

[0072] In one example, assume that the rated value of the receiving-end AC voltage of the flexible DC transmission system for photovoltaic power is 220V, the receiving-end AC active power value at the previous moment is 50kW, the rated value of the DC voltage is 500V, and the DC power at the previous moment is 45kW; at this time, the fourth preset threshold is 0.9 times the rated value of the receiving-end AC voltage, that is, 198V; the fifth preset threshold is 0.9 times the receiving-end AC active power value at the previous moment, that is, 45kW; the sixth preset threshold is 1.05 times the rated value of the DC voltage, that is, 525V; the seventh preset threshold is 1.05 times the DC power at the previous moment, that is, 47.25kW. Assume that the currently collected data is: the receiving-end AC voltage amplitude is 190V, the receiving-end AC active power is 40kW, the DC voltage amplitude is 530V, and the DC power is 48kW. Since the currently measured receiving-end AC voltage amplitude of 190V is less than the fourth preset threshold of 198V, the receiving-end AC active power of 40kW is less than the fifth preset threshold of 45kW, the DC voltage amplitude of 530V is greater than the sixth preset threshold of 475V, and the DC power of 48kW is greater than the seventh preset threshold of 47.25kW, it can be determined that there is a receiving-end AC fault.

[0073] In this embodiment, by comparing the real-time data with the preset thresholds, it is possible to quickly determine whether there is a receiving-end AC fault in the system. If the receiving-end AC voltage amplitude, the receiving-end AC active power, the DC voltage amplitude, or the DC power does not meet the preset normal operating standards (i.e., is less than or greater than the preset thresholds), it will be automatically confirmed that there is a receiving-end AC fault.

[0074] In one embodiment, the steps for detecting DC line faults in a flexible DC transmission system for photovoltaic power according to the DC voltage amplitude and the DC power include:

[0075] If the DC voltage amplitude is greater than the eighth preset threshold and the DC power is less than the ninth preset threshold, it is determined that there is a DC line fault in the flexible DC transmission system for photovoltaic power;

[0076] Among them, in the flexible DC transmission system for photovoltaic power, the eighth preset threshold is the sixth preset multiple of the rated value of the DC voltage, and the ninth preset threshold is the seventh preset multiple of the DC power at the previous moment.

[0077] Among them, the eighth preset threshold is set according to the sixth multiple of the rated value of the DC voltage and serves as a standard value for judging whether the DC voltage is normal. The ninth preset threshold is the seventh multiple of the DC power value at the previous moment and is used to judge whether the DC power is within the expected range. It can be understood that the thresholds are set based on experience, taking into account the normal deviation and fluctuation range of the power system.

[0078] Specifically, compare the obtained DC voltage amplitude with the eighth preset threshold. If the real-time voltage exceeds this threshold, it indicates that the voltage is too high and there may be voltage anomalies. At the same time, obtain the real-time data of the DC power and compare it with the ninth preset threshold. If the power is lower than this value, it may indicate that there is power loss or other abnormal phenomena in the system. Once both of these conditions are confirmed, that is, the DC voltage amplitude exceeds the eighth preset threshold and the DC power is less than the ninth preset threshold, immediately determine that there is a DC line fault in the flexible DC transmission system for PV power through judgment operations.

[0079] In an example, assume that the rated DC voltage of the flexible DC transmission system for PV power is 500V and the previous DC power value is 50kW; at this time, the eighth preset threshold is 1.05 times the rated DC voltage, that is, 525V; the ninth preset threshold is 0.95 times the previous DC power value, that is, 47.5kW. Assume that the currently collected data is: DC voltage amplitude 530V, DC power 45kW. Since the DC voltage amplitude 530 is greater than the eighth preset threshold 525V and the DC power 45kW is less than the ninth preset threshold 47.5kW, it can be judged that there is a receiving-end AC fault.

[0080] In this embodiment, by obtaining and comparing the data of the DC voltage and DC power in real time, the DC line in the flexible DC transmission system for PV power can be accurately monitored. When the DC voltage amplitude exceeds the eighth preset threshold and the DC power is lower than the ninth preset threshold, the DC line fault can be quickly judged. Without real-time threshold comparison and judgment, it may lead to the failure to detect faults in time, thereby affecting the safety and stability of the entire system. Through this dynamic monitoring based on threshold setting, the flexible DC transmission system for PV power can protect itself more efficiently, reduce the fault risk, and ensure long-term stable operation.

[0081] To facilitate the understanding of the solution of this application, specific examples are provided below for illustration.

[0082] As Figure 2As shown in the figure, the present invention proposes a method for detecting fault characteristics of a flexible DC transmission system for photovoltaic power. The AC voltage amplitude Uac1 at the sending end of the DC system, the AC active power Pac1 at the sending end, the DC voltage amplitude Udc, the DC power Pdc, the AC voltage amplitude Uac2 at the receiving end, and the AC active power Pac2 at the receiving end are collected respectively. Fault characteristics are judged based on the above electrical quantities. If the AC voltage amplitude Uac1 and the AC active power Pac1 at the sending end and the DC voltage amplitude Udc are less than a preset threshold, it is judged as an AC fault at the sending end; if the AC voltage amplitude Uac2 and the AC active power Pac2 at the receiving end are less than a preset threshold, and the DC voltage amplitude Udc and the DC power Pdc are greater than a preset threshold, it is judged as an AC fault at the receiving end; if the DC voltage amplitude Udc is greater than a preset threshold and the DC power Pdc is less than a preset threshold, it is judged as a DC line fault.

[0083] The detailed steps are as follows:

[0084] (1) Collect the AC voltage amplitude Uac1 at the sending end of the DC system, the AC active power Pac1 at the sending end, the DC voltage amplitude Udc, the DC power Pdc, the AC voltage amplitude Uac2 at the receiving end, and the AC active power Pac2 at the receiving end;

[0085] (2) Judge the fault characteristics according to the electrical quantities collected in step (1). If the AC voltage amplitude Uac1 and the AC active power Pac1 at the sending end and the DC voltage amplitude Udc are less than a preset threshold, it is judged as an AC fault at the sending end. Among them, the preset threshold of the AC voltage amplitude Uac1 at the sending end is 0.9VN1, VN1 is the rated value of the AC voltage at the sending end, the preset threshold of the AC active power Pac1 at the sending end is 0.9Pac10, Pac10 is the active power value at the previous moment, and the preset threshold of the DC voltage amplitude Udc is 0.95VdcN, VdcN is the rated value of the DC voltage;

[0086] (3) Judge the fault characteristics according to the electrical quantities collected in step (1). If the AC voltage amplitude Uac2 and the AC active power Pac2 at the receiving end are less than a preset threshold, and the DC voltage amplitude Udc and the DC power are greater than a preset threshold, it is judged as an AC fault at the receiving end. Among them, the preset threshold of the AC voltage amplitude Uac2 at the receiving end is 0.9VN2, VN2 is the rated value of the AC voltage at the receiving end, the preset threshold of the AC active power Pac2 at the receiving end is 0.9Pac20, Pac20 is the active power value at the previous moment, the preset threshold of the DC voltage amplitude Udc is 1.05VdcN, VdcN is the rated value of the DC voltage, and the preset threshold of the DC power Pdc is 1.05Pdc0, Pdc0 is the active power value at the previous moment;

[0087] (4)Judging the fault characteristics according to the electrical quantities collected in step (1). If the DC voltage amplitude Udc is greater than the preset threshold and the DC power Pdc is less than the preset threshold, it is judged as a DC line fault. The preset threshold of the DC voltage amplitude Udc is 1.05VdcN, where VdcN is the rated DC voltage, and the preset threshold of the DC power Pdc is 0.95Pdc0, where Pdc0 is the active power value at the previous moment.

[0088] The fault characteristic detection device for the photovoltaic flexible DC transmission system provided by the embodiments of the present application will be described below. The fault characteristic detection device for the photovoltaic flexible DC transmission system described below can be correspondingly referred to the fault characteristic detection method for the photovoltaic flexible DC transmission system described above. As Figure 3 shown, the present application provides a fault characteristic detection device for a photovoltaic flexible DC transmission system, and the device includes:

[0089] A data acquisition module 201, configured to collect the sending-end AC voltage amplitude, sending-end AC active power, DC voltage amplitude, DC power, receiving-end AC voltage amplitude, and receiving-end AC active power in the photovoltaic flexible DC transmission system;

[0090] A sending-end AC fault detection module 202, configured to perform sending-end AC fault detection on the photovoltaic flexible DC transmission system according to the sending-end AC voltage amplitude, sending-end AC active power, DC voltage amplitude, and DC power;

[0091] A receiving-end AC fault detection module 203, configured to perform receiving-end AC fault detection on the photovoltaic flexible DC transmission system according to the receiving-end AC voltage amplitude, receiving-end AC active power, and DC voltage amplitude;

[0092] A DC line fault detection module 204, configured to perform DC line fault detection on the photovoltaic flexible DC transmission system according to the DC voltage amplitude and DC power.

[0093] In one embodiment, the sending-end AC fault detection module 202 includes:

[0094] A sending-end AC fault detection unit, configured to determine that there is a sending-end AC fault in the photovoltaic flexible DC transmission system if the sending-end AC voltage amplitude is less than the first preset threshold, the sending-end AC active power is less than the second preset threshold, and the DC voltage amplitude is less than the third preset threshold;

[0095] Wherein, in the photovoltaic flexible DC transmission system, the first preset threshold is the first preset multiple of the sending-end AC voltage rated value, the second preset threshold is the sending-end AC active power value at the previous moment, and the third preset threshold is the second preset multiple of the DC voltage rated value.

[0096] In one embodiment, the receiving - end AC fault detection module 203 includes:

[0097] A receiving - end AC fault detection unit, configured to determine that there is a receiving - end AC fault in the PV - through - flexible - DC power transmission system if the amplitude of the receiving - end AC voltage is less than a fourth preset threshold, the receiving - end AC active power is less than a fifth preset threshold, the amplitude of the DC voltage is greater than a sixth preset threshold, and the DC power is greater than a seventh preset threshold;

[0098] Wherein, in the PV - through - flexible - DC power transmission system, the fourth preset threshold is a third preset multiple of the rated value of the receiving - end AC voltage, the fifth preset threshold is the value of the receiving - end AC active power at the previous moment, the sixth preset threshold is a fourth preset multiple of the rated value of the DC voltage, and the seventh preset threshold is a fifth preset multiple of the DC power at the previous moment.

[0099] In one embodiment, the DC line fault detection module 204 includes:

[0100] A DC line fault detection unit, configured to determine that there is a DC line fault in the PV - through - flexible - DC power transmission system if the amplitude of the DC voltage is greater than an eighth preset threshold and the DC power is less than a ninth preset threshold;

[0101] Wherein, in the PV - through - flexible - DC power transmission system, the eighth preset threshold is a sixth preset multiple of the rated value of the DC voltage, and the ninth preset threshold is a seventh preset multiple of the DC power at the previous moment.

[0102] In one embodiment, the present application further provides a storage medium, in which computer - readable instructions are stored. When the computer - readable instructions are executed by one or more processors, one or more processors are caused to execute the steps of the PV - through - flexible - DC power transmission system fault feature detection method as described in any one of the above embodiments.

[0103] In one embodiment, the present application further provides a computer device, in which computer - readable instructions are stored. When the computer - readable instructions are executed by one or more processors, one or more processors are caused to execute the steps of the PV - through - flexible - DC power transmission system fault feature detection method as described in any one of the above embodiments.

[0104] Schematically, as Figure 4 shown, Figure 4 is an internal structure schematic diagram of a computer device provided by an embodiment of the present application. The computer device 300 can be provided as a server. Referring to Figure 4, the computer device 300 includes a processing component 302, which further includes one or more processors, and memory resources represented by a memory 301 for storing instructions executable by the processing component 302, such as application programs. The application programs stored in the memory 301 may include one or more modules each corresponding to a set of instructions. In addition, the processing component 302 is configured to execute instructions to perform the photovoltaic flexible DC transmission system fault feature detection method of any of the above embodiments.

[0105] The computer device 300 may further include a power supply component 303 configured to perform power management of the computer device 300, a wired or wireless network interface 304 configured to connect the computer device 300 to a network, and an input / output (I / O) interface 305. The computer device 300 may operate based on an operating system stored in the memory 301, such as Windows Server TM, Mac OS XTM, Unix TM, Linux TM, Free BSDTM or the like.

[0106] Those skilled in the art can understand that Figure 4 the structure shown in

[0107] merely represents a block diagram of some structures related to the solution of this application, and does not constitute a limitation on the computer device to which the solution of this application is applied. A specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different component arrangement.

[0108] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0109] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting fault characteristics of a photovoltaic flexible direct current transmission system, characterized in that: The method comprises: In the photovoltaic flexible DC transmission system, the sending end AC voltage amplitude, sending end AC active power, DC voltage amplitude, DC power, receiving end AC voltage amplitude and receiving end AC active power are collected; Performing sending-end AC fault detection on the photovoltaic flexible DC transmission system according to the sending-end AC voltage amplitude, the sending-end AC active power, the DC voltage amplitude and the DC power; Performing receiving-end AC fault detection on the photovoltaic flexible DC transmission system according to the receiving-end AC voltage amplitude, the receiving-end AC active power and the DC voltage amplitude; According to the DC voltage amplitude and the DC power, a DC line fault detection is performed on the photovoltaic flexible DC transmission system.

2. The photovoltaic flexible direct current transmission system fault characteristic detection method according to claim 1 is characterized in that: The step of performing sending-end AC fault detection on the photovoltaic flexible DC transmission system according to the sending-end AC voltage amplitude, the sending-end AC active power and the DC voltage amplitude comprises: If the sending-end AC voltage amplitude is less than the first preset threshold, the sending-end AC active power is less than the second preset threshold, and the DC voltage amplitude is less than the third preset threshold, it is determined that the photovoltaic flexible DC transmission system has a sending-end AC fault; Among them, in the photovoltaic flexible direct current transmission system, the first preset threshold is a first preset multiple of the rated value of the AC voltage at the sending end, the second preset threshold is a second preset multiple of the AC active power value at the sending end at the previous moment, and the third preset threshold is a third preset multiple of the rated value of the DC voltage.

3. The photovoltaic flexible direct current transmission system fault characteristic detection method according to claim 1 is characterized in that: The step of performing sending-end AC fault detection on the photovoltaic flexible DC transmission system according to the sending-end AC voltage amplitude, the sending-end AC active power, the DC voltage amplitude and the DC power comprises: If the receiving-end AC voltage amplitude is less than the fourth preset threshold, the receiving-end AC active power is less than the fifth preset threshold, and the DC voltage amplitude is greater than the sixth preset threshold, and the DC power is greater than the seventh preset threshold, it is determined that the photovoltaic flexible DC transmission system has a receiving-end AC fault; Among them, in the photovoltaic flexible direct current transmission system, the fourth preset threshold is the fourth preset multiple of the receiving end AC voltage rating, the fifth preset threshold is the fifth preset multiple of the receiving end AC active power value at the previous moment, the sixth preset threshold is the sixth preset multiple of the DC voltage rating, and the seventh preset threshold is the seventh preset multiple of the DC power at the previous moment.

4. The photovoltaic flexible direct current transmission system fault characteristic detection method according to claim 1 is characterized in that: The step of performing DC line fault detection on the photovoltaic flexible DC transmission system according to the DC voltage amplitude and the DC power comprises: If the DC voltage amplitude is greater than an eighth preset threshold value, and the DC power is less than a ninth preset threshold value, it is determined that there is a DC line fault in the photovoltaic flexible DC transmission system; Among them, in the photovoltaic flexible DC transmission system, the eighth preset threshold is the eighth preset multiple of the DC voltage rated value, and the ninth preset threshold is the ninth preset multiple of the DC power value at the previous moment.

5. A photovoltaic flexible direct current transmission system fault characteristic detection device, characterized in that: The device comprises: The data acquisition module is used to collect the sending-end AC voltage amplitude, the sending-end AC active power, the DC voltage amplitude, the DC power, the receiving-end AC voltage amplitude and the receiving-end AC active power in the photovoltaic flexible DC transmission system; A sending-end AC fault detection module, used to perform sending-end AC fault detection on the photovoltaic flexible DC transmission system according to the sending-end AC voltage amplitude, the sending-end AC active power, the DC voltage amplitude and the DC power; A receiving-end AC fault detection module, used for performing receiving-end AC fault detection on the photovoltaic flexible DC transmission system according to the receiving-end AC voltage amplitude, the receiving-end AC active power and the DC voltage amplitude; A DC line fault detection module is used to perform DC line fault detection on the photovoltaic flexible DC transmission system according to the DC voltage amplitude and the DC power.

6. The photovoltaic flexible direct current transmission system fault characteristic detection device according to claim 1 is characterized in that: The sending-end AC fault detection module comprises: A sending-end AC fault detection unit, configured to determine that there is a sending-end AC fault in the photovoltaic flexible DC transmission system if the sending-end AC voltage amplitude is less than a first preset threshold, the sending-end AC active power is less than a second preset threshold, and the DC voltage amplitude is less than a third preset threshold; Among them, in the photovoltaic flexible direct current transmission system, the first preset threshold is a first preset multiple of the rated value of the AC voltage at the sending end, the second preset threshold is a second preset multiple of the AC active power value at the sending end at the previous moment, and the third preset threshold is a third preset multiple of the rated value of the DC voltage.

7. The photovoltaic flexible direct current transmission system fault characteristic detection device according to claim 1 is characterized in that: The receiving end AC fault detection module comprises: A receiving-end AC fault detection unit, configured to determine that there is a receiving-end AC fault in the photovoltaic flexible DC transmission system if the receiving-end AC voltage amplitude is less than a fourth preset threshold, the receiving-end AC active power is less than a fifth preset threshold, and the DC voltage amplitude is greater than a sixth preset threshold, and the DC power is greater than a seventh preset threshold; Among them, in the photovoltaic flexible direct current transmission system, the fourth preset threshold is the fourth preset multiple of the receiving end AC voltage rating, the fifth preset threshold is the fifth preset multiple of the receiving end AC active power value at the previous moment, the sixth preset threshold is the sixth preset multiple of the DC voltage rating, and the seventh preset threshold is the seventh preset multiple of the DC power at the previous moment.

8. The photovoltaic flexible direct current transmission system fault characteristic detection device according to claim 1 is characterized in that: The DC line fault detection module comprises: a DC line fault detection unit, configured to determine that a DC line fault exists in the photovoltaic flexible DC transmission system if the DC voltage amplitude is greater than an eighth preset threshold value and the DC power is less than a ninth preset threshold value; Among them, in the photovoltaic flexible DC transmission system, the eighth preset threshold is the eighth preset multiple of the DC voltage rated value, and the ninth preset threshold is the ninth preset multiple of the DC power value at the previous moment.

9. A storage medium, characterized in that: The storage medium stores computer-readable instructions, and when the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the photovoltaic flexible direct current transmission system fault characteristic detection method as described in any one of claims 1 to 4.

10. A computer device, characterized in that: include: one or more processors, and memory; The memory stores computer-readable instructions, and when the computer-readable instructions are executed by the one or more processors, the steps of the photovoltaic flexible direct current transmission system fault characteristic detection method as described in any one of claims 1 to 4 are performed.

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