Direct-current transformer high-voltage side fault identification and ride-through method and system

Abstract

The invention relates to the technical field of direct-current transformer high-voltage side fault identification and ride-through, and discloses a direct-current transformer high-voltage side fault identification and ride-through method and system, and the method comprises the steps: obtaining a first parameter of a high-voltage side of a target direct-current boosting transformer; acquiring a first fault feature according to the first parameter; the first fault feature is used for identifying a direct-current boosting transformer high-voltage side fault type; and presetting a fault ride-through strategy, and if the first fault feature of any fault type is obtained, starting the fault ride-through strategy. According to the invention, reliable identification and fault ride-through of the DC fault of the collection system can be realized by using the local measurement information of the DC transformer, the method is not influenced by photovoltaic output, the accuracy and efficiency of fault identification are improved, a new idea and method are provided for fault diagnosis of the DC boosting transformer, and the fault diagnosis efficiency of the DC boosting transformer is improved through a control and protection cooperation mode. The accuracy and efficiency of fault recognition are improved, and a new thought and method are provided for fault diagnosis of the direct-current boosting transformer.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage side fault identification and ride-through of a DC transformer, and in particular to a method and system for high-voltage side fault identification and ride-through of a DC transformer. Background Art

[0002] With the development and maturity of power electronics and DC transmission technologies, the use of DC boost-gathering and transmission systems in photovoltaic power plants has become a growing trend. DC-gathering systems offer greater stability, eliminate the need for reactive power compensation, and offer greater transmission capacity and lower losses at the same voltage level. DC boost-gathering technology for photovoltaic power plants is expected to be an effective solution to the current stability issues and overall inefficiency of photovoltaic power plants.

[0003] Photovoltaic power stations use a DC boost and collection transmission system. The DC voltage converter is an important device for system connection. The detection of high and low voltage side faults of the DC voltage converter, protection fault location and fault ride-through technology are important factors restricting the application of the DC boost and collection system.

[0004] Among the possible faults that may occur on the high-voltage side of a DC boost converter, line break faults are typically permanent and do not require a ride-through strategy. Single-pole ground faults are primarily caused by insulation failure, which can be caused by overvoltage breakdown or external forces damaging the cable insulation. Summary of the Invention

[0005] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0006] In view of the above existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides a method and system for identifying and riding through high-voltage side faults of a DC transformer, which can solve the problems mentioned in the background technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: In a first aspect, the present invention provides a method for identifying and riding through a high-voltage side fault of a DC transformer, comprising: Obtaining a first parameter of a high-voltage side of a target DC step-up transformer; The first parameter includes at least one of the following: positive and negative voltages and currents on the high-voltage side of the DC step-up transformer; Obtaining a first fault feature according to the first parameter; The first fault feature is used to identify the fault type on the high-voltage side of the DC step-up transformer; The first fault feature identifies the fault type on the high voltage side of the DC step-up transformer through a fault feature judgment standard; The fault type of the high-voltage side of the DC step-up transformer includes at least one of the following: A DC bus disconnect fault occurs on the high-voltage side of the DC transformer, a single-pole grounding fault occurs on the high-voltage side of the DC transformer, or a bipolar short circuit fault occurs on the high-voltage side of the DC transformer; A fault ride-through strategy is preset, and if the first fault feature of any fault type is obtained, the fault ride-through strategy is activated.

[0009] As a preferred solution of the method for identifying and riding through a high-voltage side fault of a DC transformer according to the present invention, obtaining the first fault feature according to the first parameter includes: Establishing a fault characteristic judgment standard based on the first parameter; Extracting a first fault feature that meets a fault feature judgment criterion; The first fault feature includes at least one of the following: a voltage fault feature and a current fault feature when the corresponding fault occurs.

[0010] As a preferred solution of the method for identifying and riding through a high-voltage side fault of a DC transformer according to the present invention, the fault characteristic judgment criteria include at least one of the following: The first criterion for judging a DC bus disconnection fault on the high-voltage side of the DC transformer; The second judgment criterion for a single-pole grounding fault on the high-voltage side of a DC transformer; and a third criterion for determining a bipolar short circuit fault on the high voltage side of a DC transformer.

[0011] As a preferred solution of the method for identifying and riding through a high-voltage side fault of a DC transformer described in the present invention, the preset fault riding through strategy includes performing fault riding through a state judgment operation of the DC transformer by design.

[0012] As a preferred solution of the method for identifying and riding through a high-voltage side fault of a DC transformer according to the present invention, the startup fault ride-through strategy includes: If the fault ride-through strategy is activated, the MPPT is switched to the output-side DC voltage control mode, and the DC converter is switched from the low-voltage side DC voltage control mode to the open-loop rated frequency control mode; Determine whether overcurrent lockout occurs in the DC / DC converter during this process.

[0013] As a preferred solution of the method for identifying and riding through a high-voltage side fault of a DC transformer according to the present invention, the startup fault ride-through strategy further includes: If overcurrent lockout occurs, wait until the DC voltage on the high-voltage side returns to the rated value before judging it as a transient fault; Switch the MPPT to the maximum power point tracking control mode and the DC step-up transformer to the fixed low-voltage side DC voltage control mode. If the DC voltage recovers, it is determined to be a temporary fault. The DC transformer is switched to the fixed low-voltage side DC voltage control mode, and the DC transformer is unlocked again. The system automatically resumes normal operation. If the DC voltage on the high-voltage side cannot be restored after the set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

[0014] As a preferred solution of the method for identifying and riding through a high-voltage side fault of a DC transformer according to the present invention, the startup fault ride-through strategy further includes: If overcurrent blocking does not occur, wait until the DC voltage on the high-voltage side returns to the rated value, then it is judged as a transient fault; Switch the MPPT to the maximum power point tracking control mode, switch the DC step-up transformer to the low-voltage side DC voltage control mode, and the system resumes normal operation; If the DC voltage on the high-voltage side cannot be restored after the set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

[0015] In a second aspect, the present invention provides a DC transformer high-voltage side fault identification and ride-through system, comprising: A data acquisition module, configured to acquire a first parameter of a high-voltage side of a target DC step-up transformer; The first parameter includes at least one of the following: positive and negative voltages and currents on the high-voltage side of the DC step-up transformer; A feature acquisition module, configured to acquire a first fault feature according to the first parameter; The first fault feature is used to identify the fault type on the high-voltage side of the DC step-up transformer; The strategy startup module is used to preset a fault ride-through strategy and start the fault ride-through strategy if the first fault feature of any fault type is obtained.

[0016] In a third aspect, the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-described method when executing the computer program.

[0017] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the method described above when the computer program is executed by a processor.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention proposes a method and system for identifying and crossing faults on the high-voltage side of a DC transformer, by obtaining a first parameter on the high-voltage side of a target DC step-up transformer; obtaining a first fault feature based on the first parameter; and presetting a fault crossing strategy. If the first fault feature of any fault type is obtained, the fault crossing strategy is activated. By utilizing the local measurement information of the DC transformer, reliable identification and fault crossing of the DC fault of the aggregation system can be achieved, and it is not affected by the photovoltaic output, which improves the accuracy and efficiency of fault identification and provides a new idea and method for fault diagnosis of DC step-up transformers. By using the collaborative control and protection method, the accuracy and efficiency of fault identification are improved, which provides a new idea and method for fault diagnosis of DC step-up transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0020] Figure 1 A flow chart of a method for identifying and riding a high-voltage side fault of a DC transformer provided by one embodiment of the present invention.

[0021] Figure 2 A DC / DC converter topology diagram of a full-bridge module + high-frequency transformer + single-phase uncontrolled rectifier bridge, providing a method for identifying and riding a DC transformer high-voltage side fault, according to one embodiment of the present invention.

[0022] Figure 3 A topology diagram of a DC boost converter grid-connected system for a DC transformer high-voltage side fault identification and ride-through method provided in accordance with an embodiment of the present invention.

[0023] Figure 4 A series-parallel topology diagram of a DC step-up transformer for a method for identifying and riding a DC transformer high-voltage side fault, provided by one embodiment of the present invention.

[0024] Figure 5 A detailed strategy flow chart of a method for identifying and riding through a high-voltage side fault of a DC transformer provided by one embodiment of the present invention.

[0025] Figure 6 An internal structural diagram of a computer device for a method for identifying and riding through a high-voltage side fault of a DC transformer provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0026] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0027] Example 1, reference Figure 1-Figure 4 , which is the first embodiment of the present invention, provides a method and system for identifying and riding through a high-voltage side fault of a DC transformer, including: There are some problems in the existing related technologies, such as inaccurate fault detection on the high-voltage side of the DC boost converter and immature fault ride-through technology, which leads to poor system stability and affects the overall operating efficiency of the photovoltaic power station.

[0028] This application provides a method that can effectively solve the above-mentioned problems. Next, we will describe in detail how to implement the DC transformer high-voltage side fault identification and ride-through method in combination with multiple embodiments. Figure 1 A method flow chart of a method and system for identifying and riding through a high-voltage side fault of a DC transformer is shown, including: S101, obtaining a first parameter of a high-voltage side of a target DC step-up transformer; In an optional embodiment, the target DC step-up transformer is as follows: Figure 2 Figure 2 shows the low-voltage side (left half): The low-voltage side consists of a full-bridge module containing four switching devices (typically MOSFETs or IGBTs). These switches are configured so that the switches on the two diagonals operate in complementary fashion. That is, when one diagonal pair of switches is on, the other pair is off. The full-bridge module converts the DC input voltage to AC voltage by controlling the on and off states of the switching devices.

[0029] High-frequency transformer: Located between the full-bridge module and the rectifier bridge, the high-frequency transformer provides isolation and voltage conversion. It converts the AC voltage generated on the low-voltage side to the voltage level required on the high-voltage side. The transformer's design allows for voltage conversion while maintaining electrical isolation, which is crucial for certain applications, such as power adapters and electric vehicle chargers.

[0030] High-voltage side (right): The high-voltage side includes a single-phase, uncontrolled rectifier bridge composed of four diodes. This bridge rectifier converts the AC voltage output from the transformer back to DC. The capacitor after the rectifier bridge acts as a filter, smoothing the output voltage and reducing ripple.

[0031] Output: The output terminal has two current sensing points (IDP and IDN) and two voltage sensing points (UDP and UDN) for monitoring the circuit's operating status. IDP and IDN measure the positive and negative output currents, respectively, while UDP and UDN measure the positive and negative output voltages.

[0032] In an optional embodiment, the first parameter on the high-voltage side of the target DC step-up transformer is used to obtain a first fault characteristic. Therefore, the selection of the first parameter on the high-voltage side of the target DC step-up transformer determines the subsequent method for obtaining the first fault characteristic and the accuracy of the fault ride-through strategy. To accurately obtain the first fault characteristic, it is necessary to ensure that the selected first parameter fully reflects the fault condition on the high-voltage side of the DC step-up transformer.

[0033] In an optional embodiment, when selecting the first parameter, in addition to considering the positive and negative voltages and currents on the high-voltage side of the DC step-up transformer, other relevant parameters, such as temperature and frequency, may be added as needed to further improve the accuracy of fault identification. These parameters can be monitored and collected in real time by sensors installed on the high-voltage side of the DC step-up transformer.

[0034] In an optional embodiment, after obtaining the first parameters, fault signature extraction is performed based on these parameters. Fault signature extraction is a key step in the fault identification and ride-through method, and its accuracy directly impacts the subsequent formulation and implementation of the fault ride-through strategy. Therefore, when extracting fault signatures, it is necessary to establish scientific and reasonable fault signature judgment criteria to ensure accurate identification of the fault type on the high-voltage side of the DC step-up transformer.

[0035] It should be noted that fault characteristic judgment criteria can include criteria for different fault types, such as DC bus disconnection, single-pole grounding faults, and bipolar short-circuit faults. These criteria can be developed based on factors such as the DC step-up transformer's structural characteristics, operating principles, and historical fault data. When developing these criteria, it is necessary to fully consider the parameter variation patterns under various fault conditions to ensure their accuracy and reliability.

[0036] In an embodiment of the present application, the first parameter includes at least one of the following: positive and negative voltages and currents on the high-voltage side of the DC step-up transformer, so the subsequent extraction of the first fault feature will be mainly based on these parameters. By real-time monitoring and analysis of the changes in the positive and negative voltages and currents on the high-voltage side of the DC step-up transformer, potential fault signs can be discovered in a timely manner. For example, when abnormal fluctuations or sudden changes in voltage or current are detected, it may mean that there is a risk of fault on the high-voltage side of the DC step-up transformer.

[0037] In an optional embodiment, the system further analyzes the degree of match between these abnormal parameters and pre-defined fault signature criteria to determine the specific fault type. Once the fault type is determined, the system immediately initiates a pre-defined fault ride-through strategy to minimize the impact of the fault on system stability and the overall operational efficiency of the PV plant.

[0038] It should be noted that obtaining the first parameters of the high-voltage side of the target DC step-up transformer provides basic data support for subsequent fault feature extraction and fault type identification. As a direct reflection of the operating status of the DC step-up transformer's high-voltage side, the accuracy and completeness of these first parameters are crucial to the success of fault identification and ride-through methods. By accurately acquiring these parameters, the system can more accurately determine whether a fault exists on the high-voltage side of the DC step-up transformer and the specific type of fault, allowing for the timely implementation of effective fault ride-through strategies to ensure system stability and the overall operational efficiency of the PV power plant. Furthermore, these first parameters can provide important reference for system fault warnings and preventive maintenance, further improving system reliability and safety.

[0039] S102, obtaining a first fault feature according to a first parameter; In the embodiment of the present application, the first fault feature is used to identify the fault type on the high-voltage side of the DC step-up transformer. The fault type on the high-voltage side of the DC step-up transformer includes at least one of the following: A DC bus disconnect fault occurs on the high-voltage side of the DC transformer, a single-pole grounding fault occurs on the high-voltage side of the DC transformer, and a bipolar short circuit fault occurs on the high-voltage side of the DC transformer.

[0040] In an optional embodiment, the first fault characteristic may include, but is not limited to, abnormal voltage fluctuations, sudden current changes, and abnormal voltage-current phase relationships. These fault characteristics are typically associated with specific fault types on the high-voltage side of the DC step-up transformer, such as a DC busbar disconnection fault, a single-pole grounding fault, or a double-pole short circuit fault. By real-time monitoring and analysis of the first parameter, the system can identify these fault characteristics and thereby determine whether a fault exists on the high-voltage side of the DC step-up transformer and the specific type of fault.

[0041] In an optional embodiment, in order to accurately obtain the first fault feature, the system needs to establish fault feature judgment criteria based on the first parameter. These judgment criteria can be formulated based on factors such as the structural characteristics, working principle, and historical fault data of the DC step-up transformer.

[0042] In an optional embodiment, during the formulation process, the system needs to fully consider the parameter variation patterns under various fault conditions to ensure the accuracy and reliability of the judgment criteria. Once the fault feature judgment criteria are established, the system can analyze and compare the first parameters monitored in real time according to these criteria to extract the first fault features that meet the judgment criteria.

[0043] In an optional embodiment, to improve the accuracy and efficiency of fault identification, the system can also employ a variety of data processing and analysis technologies, such as signal processing, pattern recognition, and machine learning. These technologies can help the system identify fault characteristics more quickly and accurately, thereby promptly initiating a preset fault ride-through strategy and reducing the impact of the fault on system stability and the overall operating efficiency of the PV power plant.

[0044] In the embodiment of the present application, obtaining the first fault feature according to the first parameter includes: Establishing a fault characteristic judgment standard based on the first parameter; Extracting a first fault feature that meets a fault feature judgment criterion; The first fault feature includes at least one of the following: a voltage fault feature and a current fault feature when the corresponding fault occurs.

[0045] In the embodiment of the present application, the fault characteristic judgment criteria include: The fault characteristic judgment criteria include at least one of the following: a first judgment criterion for a DC bus disconnection fault occurring on the high voltage side of the DC transformer; The second judgment criterion for a single-pole grounding fault on the high-voltage side of a DC transformer; and a third criterion for determining a bipolar short circuit fault on the high voltage side of a DC transformer.

[0046] In an optional embodiment, the first judgment criterion, the second judgment criterion, and the third judgment criterion can be formulated based on factors such as the structural characteristics, working principle, and historical fault data of the DC step-up transformer, and can be verified and continuously optimized through experiments to ensure their accuracy and reliability. For example, for a DC bus disconnection fault, the first judgment criterion can be set to be determined as a DC bus disconnection fault when it is detected that the DC voltage on the high-voltage side drops sharply and the current is almost zero. For a single-pole grounding fault, the second judgment criterion can be set to be determined as a single-pole grounding fault when it is detected that the voltage of one pole on the high-voltage side drops significantly, while the voltage of the other pole remains unchanged or increases slightly, and the current is unbalanced. For a bipolar short circuit fault, the third judgment criterion can be set to be determined as a bipolar short circuit fault when it is detected that the voltages of the positive and negative poles on the high-voltage side drop sharply at the same time and the current increases significantly.

[0047] In an optional embodiment, when developing fault signature judgment criteria, it is also necessary to consider the mutual influence and interference between different fault types. For example, in some cases, one fault type may cause the characteristics of another fault type to appear, or multiple fault types may occur simultaneously, making the identification and judgment of fault characteristics more complex. Therefore, when developing fault signature judgment criteria, it is necessary to fully consider these special circumstances and take appropriate measures to distinguish and identify them.

[0048] In an optional embodiment, to improve the accuracy and efficiency of fault identification, the system can also utilize various data processing and analysis technologies, such as signal processing, pattern recognition, and machine learning. These technologies can help the system identify fault characteristics more quickly and accurately, thereby promptly initiating preset fault ride-through strategies and reducing the impact of faults on system stability and the overall operational efficiency of the PV power plant. For example, machine learning algorithms can be used to train and learn from historical fault data to establish a mapping model between fault characteristics and fault types. This allows the system to quickly and accurately identify fault types and implement corresponding fault ride-through strategies when new fault characteristics are detected in real time.

[0049] Specifically, the voltage and current signals at the high-voltage side of the DC transformer are collected in real time. 、 、 、 , identify the high-voltage side fault of the DC transformer based on the voltage and current fault characteristics: If criterion (1) is met, a DC busbar disconnection fault occurs on the high-voltage side of the DC transformer, which is the first judgment criterion in this application.

[0050] (1) in, It is the fixed value of the pole bus current, which is generally set to 0.05pu in engineering. It is the set value of the DC bus current change rate, which is generally set to 0.2pu / 0.1ms in engineering. is the time variable.

[0051] If criterion (2) is met, a single-pole grounding fault occurs on the high-voltage side of the DC transformer, which is the second criterion in this application.

[0052] (2) in, It is the unbalanced voltage setting value of the positive and negative DC bus, which is generally set to 0.5pu in engineering. It is the extremely low DC bus voltage setting value, which is generally set to 0.3pu in engineering.

[0053] If criterion (3) is met, a bipolar short circuit fault occurs on the high voltage side of the DC transformer, which is the third criterion in this application.

[0054] (3) in, It is the fixed value of the pole bus voltage, which is generally set to 0.3pu in engineering. It is the set value of the DC bus current change rate, which is generally set to 0.2pu / 0.1ms in engineering.

[0055] It should be noted that when the above formula is satisfied, the first fault feature of the corresponding fault is extracted, and the fault type is determined based on the extracted first fault feature. If the result is a DC bus disconnect fault, a ride-through strategy for the DC bus disconnect fault is initiated; if the result is a single-pole ground fault, a ride-through strategy for single-pole ground faults is initiated; if the result is a double-pole short circuit fault, a ride-through strategy for double-pole short circuit faults is initiated. These ride-through strategies may include, but are not limited to, adjusting system parameters, switching to backup power sources, and isolating the faulty area to minimize the impact of the fault on system stability and the overall operating efficiency of the PV power station.

[0056] In an optional embodiment, the formulation of the fault ride-through strategy needs to take into account factors such as the structural characteristics, working principle, and fault type of the DC step-up transformer. For example, for a DC bus line break fault, the ride-through strategy may include measures such as quickly disconnecting the fault line and starting the backup DC bus to ensure continuous power supply to the system. For a single-pole grounding fault, the ride-through strategy may include adjusting system parameters, such as changing the grounding resistance value, to balance the voltage and current of the positive and negative poles to prevent further expansion of the fault. For a bipolar short circuit fault, the ride-through strategy may include immediately cutting off the power supply to the fault area and isolating the faulty equipment to protect other normally operating equipment from being affected.

[0057] In an optional embodiment, to improve the efficiency and accuracy of fault ride-through, the system can also employ advanced control algorithms and intelligent decision-making technologies. For example, intelligent control algorithms such as fuzzy control and neural networks can be used to optimize and control the fault ride-through process, achieving faster and more accurate fault ride-through. Furthermore, technologies such as big data analysis and cloud computing can be used to mine and analyze historical fault data to identify patterns and trends in fault occurrence, providing a scientific basis for formulating fault ride-through strategies.

[0058] In an optional embodiment, a series of preventative maintenance measures can be implemented to improve system reliability and safety. For example, regular inspections and maintenance of the DC step-up transformer can be performed to promptly identify and address potential faults. Furthermore, a fault early warning mechanism can be established to monitor and analyze the system's operating status in real time, promptly identifying abnormal parameters and signs of faults. This allows preventive measures to be taken before a fault occurs, preventing it from occurring and escalating.

[0059] It should be noted that obtaining the first fault signature based on the first parameter provides critical information for subsequent fault type identification and ride-through strategy development. By accurately extracting and analyzing the first fault signature, the system can more quickly identify the fault type on the high-voltage side of the DC step-up transformer, enabling timely activation of the appropriate fault ride-through strategy and minimizing the fault's impact on the system. This rapid and accurate fault identification and ride-through capability is crucial for ensuring system stability and the overall operational efficiency of the PV power plant. Furthermore, obtaining the first fault signature facilitates fault early warning and preventive maintenance, further improving system reliability and safety.

[0060] S103: Preset a fault ride-through strategy. If a first fault feature of any fault type is obtained, start the fault ride-through strategy.

[0061] In an embodiment of the present application, the preset fault ride-through strategy includes performing fault ride-through on the state judgment operation of the DC transformer by design.

[0062] In an optional embodiment, the fault ride-through strategy may include, but is not limited to, adjusting system parameters, switching to backup power supplies, isolating the fault area, restarting the DC transformer, and other measures. The formulation of these strategies needs to be comprehensively considered based on factors such as the structural characteristics, working principle, and fault type of the DC step-up transformer. For example, for a DC bus line break fault, the ride-through strategy may include quickly disconnecting the fault line, starting the backup DC bus, and adjusting system parameters to ensure continuous power supply to the system. For a single-pole grounding fault, the ride-through strategy may include adjusting the grounding resistance value, balancing the voltage and current of the positive and negative poles, preventing the fault from further expanding, and monitoring the system status to determine whether further measures are needed.

[0063] In an optional embodiment, for a bipolar short-circuit fault, the ride-through strategy may include immediately shutting off power to the faulted area, isolating the faulty equipment, activating backup protection devices to protect other normally operating equipment, and quickly restoring system operation. When developing a fault ride-through strategy, it is necessary to fully consider the system's response and recovery capabilities under various fault scenarios to ensure its effectiveness and reliability.

[0064] In an optional embodiment, to improve the efficiency and accuracy of fault ride-through, advanced control algorithms and intelligent decision-making technologies, such as fuzzy control and neural networks, can be used to optimize and control the fault ride-through process. At the same time, big data analysis and cloud computing can be used to mine and analyze historical fault data to discover patterns and trends in fault occurrence, providing a scientific basis for the formulation of fault ride-through strategies and a direction for continuous optimization.

[0065] In the embodiment of the present application, starting the fault ride-through strategy includes: If the first fault feature of any fault type is obtained, the fault ride-through strategy is activated; Switch the MPPT to the output side DC voltage control mode, and switch the DC converter from the low-voltage side DC voltage control mode to the open-loop rated frequency control mode; Determine whether overcurrent lockout occurs in the DC / DC converter during this process.

[0066] In the embodiment of the present application, starting the fault ride-through strategy further includes: If overcurrent lockout occurs, wait until the DC voltage on the high-voltage side returns to the rated value before judging it as a transient fault; Switch the MPPT to the maximum power point tracking control mode and the DC step-up transformer to the fixed low-voltage side DC voltage control mode. If the DC voltage recovers, it is determined to be a temporary fault. The DC transformer is switched to the fixed low-voltage side DC voltage control mode, and the DC transformer is unlocked again. The system automatically resumes normal operation. If the DC voltage on the high-voltage side cannot be restored after the set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

[0067] In the embodiment of the present application, starting the fault ride-through strategy further includes: If overcurrent blocking does not occur, wait until the DC voltage on the high-voltage side returns to the rated value, then it is judged as a transient fault; Switch the MPPT to the maximum power point tracking control mode, switch the DC step-up transformer to the low-voltage side DC voltage control mode, and the system resumes normal operation; If the DC voltage on the high-voltage side cannot be restored after the set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

[0068] like Figure 3As shown in the figure, the photovoltaic array is the source of DC power in the system. It consists of multiple photovoltaic panels that convert sunlight into electricity. The MPPT controller ensures that the photovoltaic array always operates at its maximum power point under varying light and temperature conditions. This maximizes the energy output of the photovoltaic array. The MPPT controller typically adjusts the operating voltage and current of the photovoltaic array to achieve optimal power output. The DC boost converter boosts the lower voltage output of the photovoltaic array to a higher voltage level for subsequent inverter operation and grid connection. This converter increases the voltage while maintaining or increasing the current to meet grid connection requirements. The grid-connected inverter converts the boosted DC power into AC power and injects it into the grid. The inverter must meet grid standards such as frequency, voltage, and phase to ensure safe grid connection. The grid is the final destination for the power output of the grid-connected inverter. The grid is typically a three-phase AC system, and the AC power output of the inverter must be synchronized with the grid for stable grid connection.

[0069] like Figure 4 The figure shows a topology diagram of several parallel DC step-up transformers. This topology diagram shows the design of increasing the voltage level and transmission capacity of the DC system by connecting multiple DC step-up transformers in parallel. Each DC step-up transformer has independent input and output ports, and they are electrically isolated from each other to ensure stable operation. Figure 4 In the diagram, it can be clearly seen that the high-voltage and low-voltage sides of each DC step-up transformer are connected to the rest of the system via wires, forming an efficient energy transmission path. Furthermore, this topology diagram illustrates the layout considerations for practical applications of fault identification and ride-through methods, ensuring that when a fault occurs, the system can quickly identify and implement ride-through measures to maintain stable operation of the DC system.

[0070] In summary, the present invention proposes a method for identifying and crossing faults on the high-voltage side of a DC transformer, obtaining a first parameter on the high-voltage side of a target DC step-up transformer; the first parameter includes at least one of the following: positive and negative voltages and currents on the high-voltage side of the DC step-up transformer; obtaining a first fault feature based on the first parameter; the first fault feature is used to identify the type of fault on the high-voltage side of the DC step-up transformer; a preset fault crossing strategy, if the first fault feature of any fault type is obtained, the fault crossing strategy is activated. By utilizing the local measurement information of the DC transformer, reliable identification and fault crossing of the DC fault of the aggregation system can be achieved, and it is not affected by the photovoltaic output, which improves the accuracy and efficiency of fault identification, and provides a new idea and method for fault diagnosis of the DC step-up transformer. By using the collaborative control and protection method, the accuracy and efficiency of fault identification are improved, and a new idea and method for fault diagnosis of the DC step-up transformer is provided.

[0071] Example 2, in a preferred embodiment, provides a detailed specific implementable operation steps, such as Figure 5 As shown, the voltage and current signals at the high-voltage side of the DC transformer are collected in real time. 、 、 、 , identify the high-voltage side fault of the DC transformer based on the voltage and current fault characteristics: If criterion (1) is met, a DC busbar disconnection fault occurs on the high-voltage side of the DC transformer, which is the first judgment criterion in this application.

[0072] (1) in, It is the fixed value of the pole bus current, which is generally set to 0.05pu in engineering. It is the set value of the DC bus current change rate, which is generally set to 0.2pu / 0.1ms in engineering.

[0073] If criterion (2) is met, a single-pole grounding fault occurs on the high-voltage side of the DC transformer, which is the second criterion in this application.

[0074] (2) in, It is the unbalanced voltage setting value of the positive and negative DC bus, which is generally set to 0.5pu in engineering. It is the extremely low DC bus voltage setting value, which is generally set to 0.3pu in engineering.

[0075] If criterion (3) is met, a bipolar short circuit fault occurs on the high voltage side of the DC transformer, which is the third criterion in this application.

[0076] (3) in, It is the fixed value of the pole bus voltage, which is generally set to 0.3pu in engineering. It is the set value of the DC bus current change rate, which is generally set to 0.2pu / 0.1ms in engineering.

[0077] Furthermore, after identifying a fault on the DC high-voltage side, the fault ride-through strategy is initiated; the MPPT is switched to the output-side DC voltage control mode, and the DC converter is switched from the low-voltage side DC voltage control mode to the open-loop rated frequency control mode; and it is determined whether the DC / DC converter has an overcurrent lockout during this process; If an overcurrent lockout occurs, wait until the high-voltage side DC voltage returns to rated value, then it is judged as a transient fault, the MPPT is switched to maximum power point tracking control mode, the DC step-up transformer is switched to low-voltage side DC voltage control mode, and the system is unlocked again to resume normal operation. If the high-voltage side DC voltage cannot be restored after the set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

[0078] If overcurrent lockout does not occur, wait until the high-voltage side DC voltage returns to rated value, then it is judged as a transient fault, the MPPT is switched to maximum power point tracking control mode, the DC step-up transformer is switched to low-voltage side DC voltage control mode, and the system resumes normal operation; if the high-voltage side DC voltage cannot be restored after the set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

[0079] It should be noted that by analyzing the fault characteristics of the high-voltage side of the DC transformer and reliably detecting the system fault condition based on the fault characteristics of the high-voltage side of the DC transformer, the fault ride-through strategy is then activated, switching the DC converter from the low-voltage side DC voltage control mode to the open-loop rated frequency control mode, waiting for the high-voltage side DC voltage to recover. After a set time, the DC voltage recovery is determined to determine whether it is a transient fault. The DC transformer is then switched to the low-voltage side DC voltage control mode, the DC transformer is unlocked again, and the system automatically resumes normal operation. This method is applicable to photovoltaic DC boost collection systems. Through the coordinated control and protection, it improves the accuracy and efficiency of fault identification and provides new ideas and methods for DC boost transformer fault diagnosis.

[0080] Example 3: This embodiment also provides a DC transformer high-voltage side fault identification and ride-through system, including: A data acquisition module, configured to acquire a first parameter of a high-voltage side of a target DC step-up transformer; The first parameter includes at least one of the following: positive and negative voltages and currents on the high-voltage side of the DC step-up transformer; A feature acquisition module, configured to acquire a first fault feature according to a first parameter; The first fault feature is used to identify the fault type on the high-voltage side of the DC step-up transformer; The strategy startup module is used to preset a fault ride-through strategy and start the fault ride-through strategy if the first fault feature of any fault type is obtained.

[0081] The above-mentioned unit modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the corresponding operations of the above-mentioned modules.

[0082] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as shown in FIG. Figure 6 As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner. The wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a method for identifying and traversing a high-voltage side fault of a DC transformer is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device can be a touch layer covering the display screen, or a key, trackball or touchpad provided on the computer device housing, or an external keyboard, touchpad or mouse.

[0083] This embodiment further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the following steps are implemented: Obtaining a first parameter of a high-voltage side of a target DC step-up transformer; The first parameter includes at least one of the following: positive and negative voltages and currents on the high-voltage side of the DC step-up transformer; Obtaining a first fault feature according to the first parameter; The first fault feature is used to identify the fault type on the high-voltage side of the DC step-up transformer; A fault ride-through strategy is preset, and if the first fault feature of any fault type is obtained, the fault ride-through strategy is activated.

[0084] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0085] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of a fully hardware embodiment, a fully software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present application may be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0086] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0087] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0088] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0089] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0090] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A method for identifying and riding through a high-voltage side fault of a DC transformer, characterized in that: include: Obtaining a first parameter of a high-voltage side of a target DC step-up transformer; The first parameter includes at least one of the following: positive and negative voltages and currents on the high-voltage side of the DC step-up transformer; Obtaining a first fault feature according to the first parameter; The first fault feature is used to identify the fault type on the high-voltage side of the DC step-up transformer; The first fault feature identifies the fault type on the high voltage side of the DC step-up transformer through a fault feature judgment standard; The fault type of the high-voltage side of the DC step-up transformer includes at least one of the following: A DC bus disconnect fault occurs on the high-voltage side of the DC transformer, a single-pole grounding fault occurs on the high-voltage side of the DC transformer, or a bipolar short circuit fault occurs on the high-voltage side of the DC transformer; A fault ride-through strategy is preset, and if the first fault feature of any fault type is obtained, the fault ride-through strategy is activated.

2. A method for identifying and riding through a high-voltage side fault of a DC transformer according to claim 1, characterized in that: Acquiring the first fault feature according to the first parameter includes: Establishing a fault characteristic judgment standard based on the first parameter; Extracting a first fault feature that meets a fault feature judgment criterion; The first fault feature includes at least one of the following: a voltage fault feature and a current fault feature when the corresponding fault occurs.

3. A method for identifying and riding through a high-voltage side fault of a DC transformer according to claim 2, characterized in that: The fault characteristic judgment criteria include at least one of the following: The first criterion for judging a DC bus disconnection fault on the high-voltage side of the DC transformer; The second judgment criterion for a single-pole grounding fault on the high-voltage side of a DC transformer; and a third criterion for determining a bipolar short circuit fault on the high voltage side of a DC transformer.

4. A method for identifying and riding through a high-voltage side fault of a DC transformer according to claim 3, characterized in that: The preset fault ride-through strategy includes designing a state judgment operation of the DC transformer to perform fault ride-through.

5. A method for identifying and riding through a high-voltage side fault of a DC transformer according to claim 4, characterized in that: The startup fault ride-through strategy includes: If the fault ride-through strategy is activated, the MPPT is switched to the output-side DC voltage control mode, and the DC converter is switched from the low-voltage side DC voltage control mode to the open-loop rated frequency control mode; Determine whether overcurrent lockout occurs in the DC / DC converter during this process.

6. A method for identifying and riding through a high-voltage side fault of a DC transformer according to claim 5, characterized in that: The startup fault ride-through strategy further includes: If overcurrent lockout occurs, wait until the DC voltage on the high-voltage side returns to the rated value before judging it as a transient fault; Switch the MPPT to the maximum power point tracking control mode and the DC step-up transformer to the fixed low-voltage side DC voltage control mode. If the DC voltage recovers, it is determined to be a temporary fault. The DC transformer is switched to the fixed low-voltage side DC voltage control mode, and the DC transformer is unlocked again. The system automatically resumes normal operation. If the DC voltage on the high-voltage side cannot be restored after the set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

7. A method for identifying and riding through a high-voltage side fault of a DC transformer according to claim 6, characterized in that: The startup fault ride-through strategy further includes: If overcurrent blocking does not occur, wait until the DC voltage on the high-voltage side returns to the rated value, then it is judged as a transient fault; Switch the MPPT to the maximum power point tracking control mode, switch the DC step-up transformer to the low-voltage side DC voltage control mode, and the system resumes normal operation; If the DC voltage on the high-voltage side cannot be restored after the set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

8. A DC transformer high-voltage side fault identification and ride-through system, using a DC transformer high-voltage side fault identification and ride-through method according to any one of claims 1 to 7, characterized in that: include: A data acquisition module, configured to acquire a first parameter of a high-voltage side of a target DC step-up transformer; The first parameter includes at least one of the following: positive and negative voltages and currents on the high-voltage side of the DC step-up transformer; A feature acquisition module, configured to acquire a first fault feature according to the first parameter; The first fault feature is used to identify the fault type on the high-voltage side of the DC step-up transformer; The strategy startup module is used to preset a fault ride-through strategy and start the fault ride-through strategy if the first fault feature of any fault type is obtained.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of a method for identifying and riding through a high-voltage side fault of a DC transformer according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a method for identifying and riding through a high-voltage side fault of a DC transformer according to any one of claims 1 to 7 are implemented.

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