A method and system for recognizing and crossing high-voltage side fault of direct-current transformer

Abstract

The present application relates to the technical field of DC transformer high-voltage side fault identification and crossing, and discloses a DC transformer high-voltage side fault identification and crossing method and system, the method comprising: obtaining a first parameter of a target DC booster transformer high-voltage side; obtaining a first fault feature according to the first parameter; the first fault feature is used for identifying the fault type of the DC booster transformer high-voltage side; a preset fault crossing strategy is started if the first fault feature of any fault type is obtained. The present application can realize reliable identification and fault crossing of the DC fault of the collection system by using the local measurement information of the DC transformer, is not affected by the photovoltaic output, improves the accuracy and efficiency of fault identification, provides a new idea and method for fault diagnosis of the DC booster transformer, and improves the accuracy and efficiency of fault identification through the collaborative mode of control and protection, which provides a new idea and method for fault diagnosis of the DC booster transformer.

Description

Technical Field

[0001] This invention relates to the field of fault identification and ride-through technology on the high-voltage side of DC transformers, and particularly to a method and system for fault identification and ride-through on the high-voltage side of DC transformers. Background Technology

[0002] With the development and maturation of power electronics and DC transmission technologies, the adoption of DC boost-collection and transmission systems in photovoltaic power plants has become a growing trend. DC collection systems offer higher stability, require no reactive power compensation, and have greater transmission capacity and lower losses at the same voltage level. DC boost-collection technology for photovoltaic power plants holds promise as an effective way to solve the current stability problems and overall low efficiency of photovoltaic power plants.

[0003] Photovoltaic power plants use DC boost collection and transmission systems. DC voltage converters are important equipment for system connection. The detection, protection, fault location, and fault ride-through technologies of high and low voltage side faults of DC voltage converters are important factors restricting the application of DC boost collection systems.

[0004] Among the faults that may occur on the high-voltage side of a DC-DC boost converter, open-circuit faults are usually permanent and do not require consideration of ride-through strategies. Single-pole grounding faults are mainly caused by insulation failure, which may be caused by overvoltage breakdown or external force damaging the cable insulation layer. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

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

[0007] Therefore, the present invention provides a method and system for fault identification and ride-through on the high-voltage side of a DC transformer, which can solve the problems mentioned in the background art.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0009] In a first aspect, the present invention provides a method for fault identification and ride-through on the high-voltage side of a DC transformer, comprising:

[0010] Obtain the first parameters of the high-voltage side of the target DC step-up transformer;

[0011] The first parameter includes at least one of the following: the positive and negative voltages and current on the high-voltage side of the DC step-up transformer;

[0012] The first fault characteristic is obtained based on the first parameter;

[0013] The first fault feature is used to identify the fault type on the high-voltage side of the DC step-up transformer;

[0014] The first fault characteristic identifies the fault type on the high-voltage side of the DC step-up transformer using fault characteristic judgment criteria;

[0015] The fault types on the high-voltage side of the DC step-up transformer include at least one of the following:

[0016] A DC bus disconnection 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 double-pole short-circuit fault occurs on the high-voltage side of the DC transformer.

[0017] A default fault traversal strategy is set up. If the first fault characteristic of any fault type is obtained, the fault traversal strategy is activated.

[0018] As a preferred embodiment of the DC transformer high-voltage side fault identification and ride-through method described in this invention, the step of obtaining the first fault feature based on the first parameter includes:

[0019] Establish a fault characteristic judgment standard based on the first parameter;

[0020] Extract the first fault feature that meets the fault feature judgment criteria;

[0021] The first fault feature includes at least one of the following: voltage fault features and current fault features corresponding to the occurrence of the fault.

[0022] As a preferred embodiment of the DC transformer high-voltage side fault identification and ride-through method described in this invention, the fault characteristic judgment criteria include at least one of the following:

[0023] The first criterion for judging a DC bus disconnection fault on the high-voltage side of a DC transformer;

[0024] A second criterion for judging the occurrence of a single-pole grounding fault on the high-voltage side of a DC transformer;

[0025] And a third criterion for judging bipolar short-circuit faults on the high-voltage side of DC transformers.

[0026] As a preferred embodiment of the DC transformer high-voltage side fault identification and ride-through method described in this invention, the preset fault ride-through strategy includes fault ride-through by designing the state judgment operation of the DC transformer.

[0027] As a preferred embodiment of the DC transformer high-voltage side fault identification and ride-through method described in this invention, the fault ride-through initiation strategy includes:

[0028] If the fault ride-through strategy is activated, the MPPT will be switched to the output-side DC voltage control mode, and the DC converter will be switched from the low-voltage-side DC voltage control mode to the open-loop rated frequency control mode.

[0029] Determine whether the DC / DC converter experiences overcurrent blocking during this process.

[0030] As a preferred embodiment of the fault identification and ride-through method for the high-voltage side of a DC transformer according to the present invention, the fault ride-through initiation strategy further includes:

[0031] If an overcurrent blockage occurs, the fault is considered transient once the DC voltage on the high-voltage side returns to its rated value.

[0032] Switch the MPPT to maximum power point tracking control mode, switch the DC step-up transformer to constant low voltage side DC voltage control mode. If the DC voltage recovers, it is determined to be a temporary fault. Switch the DC transformer to constant low voltage side DC voltage control mode, unlock the DC transformer again, and the system will automatically resume normal operation.

[0033] If the DC voltage on the high-voltage side cannot be restored after a set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

[0034] As a preferred embodiment of the fault identification and ride-through method for the high-voltage side of a DC transformer according to the present invention, the fault ride-through initiation strategy further includes:

[0035] If no overcurrent blocking occurs, the fault is judged to be transient once the DC voltage on the high-voltage side returns to its rated value.

[0036] Switch the MPPT to maximum power point tracking control mode and switch the DC step-up transformer to low-voltage side DC voltage control mode. The system will then return to normal operation.

[0037] If the DC voltage on the high-voltage side cannot be restored after a set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

[0038] Secondly, the present invention provides a fault identification and ride-through system for the high-voltage side of a DC transformer, comprising:

[0039] The data acquisition module is used to acquire the first parameters of the high-voltage side of the target DC step-up transformer;

[0040] The first parameter includes at least one of the following: the positive and negative voltages and current on the high-voltage side of the DC step-up transformer;

[0041] The feature acquisition module is used to acquire the first fault feature based on the first parameter;

[0042] The first fault feature is used to identify the fault type on the high-voltage side of the DC step-up transformer;

[0043] The strategy initiation module is used to preset the fault traversal strategy. If the first fault characteristic of any fault type is obtained, the fault traversal strategy is activated.

[0044] Thirdly, the present invention provides a computer device including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described above.

[0045] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described above.

[0046] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention proposes a method and system for fault identification and fault ride-through on the high-voltage side of a DC transformer. It obtains first parameters of the high-voltage side of the target DC step-up transformer; acquires first fault characteristics based on the first parameters; and presets a fault ride-through strategy. If the first fault characteristics of any fault type are acquired, the fault ride-through strategy is activated. By utilizing local measurement information of the DC transformer, reliable identification and fault ride-through of DC faults in the collection system can be achieved, unaffected by photovoltaic output, thus improving the accuracy and efficiency of fault identification and providing a new approach and method for fault diagnosis of DC step-up transformers. Through a control-protection coordination approach, the accuracy and efficiency of fault identification are improved, providing a new approach and method for fault diagnosis of DC step-up transformers. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a flowchart of a method for identifying and traversing faults on the high-voltage side of a DC transformer, provided as an embodiment of the present invention.

[0049] Figure 2 This is a DC / DC converter topology diagram of a full-bridge module + high-frequency transformer + single-phase uncontrolled rectifier bridge, which is provided as an embodiment of the present invention for a method for identifying and traversing faults on the high-voltage side of a DC transformer.

[0050] Figure 3The topology of a DC step-up converter grid-connected system is provided for a DC transformer high-voltage side fault identification and ride-through method according to an embodiment of the present invention.

[0051] Figure 4 This is a DC step-up transformer series-parallel topology diagram for a DC transformer high-voltage side fault identification and ride-through method provided in one embodiment of the present invention.

[0052] Figure 5 This is a detailed strategy flowchart of a DC transformer high-voltage side fault identification and ride-through method provided in one embodiment of the present invention.

[0053] Figure 6 This is an internal structural diagram of a computer device for a DC transformer high-voltage side fault identification and ride-through method provided in one embodiment of the present invention. Detailed Implementation

[0054] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0055] Example 1, referring to Figures 1-4 This is the first embodiment of the present invention, which provides a method and system for fault identification and ride-through on the high-voltage side of a DC transformer, including:

[0056] Existing technologies have some problems, such as inaccurate fault detection on the high-voltage side of DC boost converters and immature fault ride-through technology, which lead to poor system stability and affect the overall operating efficiency of photovoltaic power plants.

[0057] This application provides a method that can effectively solve the problems mentioned above. The following will describe in detail how to implement the DC transformer high-voltage side fault identification and ride-through method with multiple embodiments.

[0058] Figure 1 A flowchart illustrating a method and system for fault identification and ride-through on the high-voltage side of a DC transformer is shown, including:

[0059] S101, Obtain the first parameter of the high-voltage side of the target DC step-up transformer;

[0060] In an optional embodiment, the target DC step-up transformer is as follows: Figure 2As shown, 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 switching devices are configured such that the switches on two diagonals operate complementaryly; that is, when one pair of diagonal switches is on, the other pair is off. The function of the full-bridge module is to convert the DC input voltage to AC voltage by controlling the on and off states of the switching devices.

[0061] High-frequency transformer: Located between the full-bridge module and the rectifier bridge, the high-frequency transformer is used for voltage isolation and transformation. It converts the AC voltage generated on the low-voltage side to the required voltage level on the high-voltage side. The transformer's design allows for voltage transformation while maintaining electrical isolation, which is crucial for certain applications such as power adapters, electric vehicle chargers, etc.

[0062] High-voltage side (right half): The high-voltage side contains a single-phase uncontrolled rectifier bridge, composed of four diodes. The function of this rectifier bridge is to convert the AC voltage output from the transformer back to DC voltage. The capacitor after the rectifier bridge acts as a filter, smoothing the output voltage and reducing ripple.

[0063] Output terminals: The output terminals have two current sensing points (IDP and IDN) and two voltage sensing points (UDP and UDN) to monitor 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.

[0064] In one optional embodiment, the first parameter on the high-voltage side of the target DC-DC step-up transformer is used to obtain the first fault characteristic. Therefore, the selection of the first parameter on the high-voltage side of the target DC-DC step-up transformer determines the subsequent method of obtaining the first fault characteristic and the accuracy of the fault ride-through strategy. In order to accurately obtain the first fault characteristic, it is necessary to ensure that the selected first parameter can comprehensively reflect the fault situation on the high-voltage side of the DC-DC step-up transformer.

[0065] 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-DC step-up transformer, other relevant parameters, such as temperature and frequency, can 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-DC step-up transformer.

[0066] In an optional embodiment, after obtaining the first parameters, fault feature extraction needs to be performed based on these parameters. Fault feature extraction is one of the key steps in the fault identification and ride-through method, and its accuracy directly affects the formulation and execution of subsequent fault ride-through strategies. Therefore, when extracting fault features, it is necessary to establish scientific and reasonable fault feature judgment criteria to ensure that the fault type on the high-voltage side of the DC step-up transformer can be accurately identified.

[0067] It should be noted that fault characteristic judgment criteria can include those for different fault types such as DC bus open circuit faults, single-pole grounding faults, and double-pole short circuit faults. 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. When formulating judgment criteria, it is necessary to fully consider the parameter variation patterns under various fault conditions to ensure the accuracy and reliability of the judgment criteria.

[0068] In this embodiment, the first parameter includes at least one of the following: the positive and negative voltages and current on the high-voltage side of the DC-DC step-up transformer. Therefore, the subsequent extraction of the first fault characteristics will be mainly based on these parameters. By real-time monitoring and analysis of changes in the positive and negative voltages and current on the high-voltage side of the DC-DC step-up transformer, potential fault signs can be detected 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 fault risk on the high-voltage side of the DC-DC step-up transformer.

[0069] In an optional embodiment, the system will further analyze the degree of matching between these abnormal parameters and preset fault characteristic judgment criteria to determine the specific fault type. Once the fault type is determined, the system will immediately activate a preset fault ride-through strategy to minimize the impact of the fault on system stability and the overall operating efficiency of the photovoltaic power plant.

[0070] It should be noted that obtaining the first parameters of the high-voltage side of the target DC-DC step-up transformer provides fundamental data support for subsequent fault feature extraction and fault type identification. These first parameters, as a direct reflection of the operating status of the high-voltage side of the DC-DC step-up transformer, are crucial to the success of fault identification and fault ride-through methods due to their accuracy and completeness. By accurately acquiring these parameters, the system can more accurately determine whether a fault exists on the high-voltage side of the DC-DC step-up transformer and the specific type of fault, thereby enabling timely and effective fault ride-through strategies to ensure system stability and the overall operating efficiency of the photovoltaic power station. Furthermore, these first parameters can also provide important references for system fault early warning and preventative maintenance, further improving system reliability and safety.

[0071] S102, Obtain the first fault characteristic based on the first parameter;

[0072] In this embodiment of the application, the first fault feature is used to identify the fault type on the high-voltage side of the DC-DC step-up transformer, and the fault type on the high-voltage side of the DC-DC step-up transformer includes at least one of the following:

[0073] The faults include: DC bus disconnection on the high-voltage side of the DC transformer, single-pole grounding fault on the high-voltage side of the DC transformer, and double-pole short-circuit fault on the high-voltage side of the DC transformer.

[0074] 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 DC bus disconnection faults, single-pole grounding faults, or double-pole short-circuit faults. By real-time monitoring and analysis of the first parameter, the system can identify these fault characteristics, thereby determining whether a fault exists on the high-voltage side of the DC step-up transformer and the specific type of fault.

[0075] In an optional embodiment, in order to accurately obtain the first fault characteristic, the system needs to establish fault characteristic 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.

[0076] In an optional embodiment, during the development 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 characteristic judgment criteria are established, the system can analyze and compare the first parameters monitored in real time according to these criteria, thereby extracting the first fault characteristics that meet the judgment criteria.

[0077] In an optional embodiment, to improve the accuracy and efficiency of fault identification, the system can also employ various data processing and analysis techniques, such as signal processing, pattern recognition, and machine learning. These techniques can help the system identify fault characteristics more quickly and accurately, thereby promptly activating preset fault ride-through strategies and reducing the impact of faults on system stability and the overall operating efficiency of the photovoltaic power plant.

[0078] In this embodiment of the application, obtaining the first fault characteristic based on the first parameter includes:

[0079] Establish a fault characteristic judgment standard based on the first parameter;

[0080] Extract the first fault feature that meets the fault feature judgment criteria;

[0081] The first fault characteristic includes at least one of the following: voltage fault characteristics and current fault characteristics corresponding to the occurrence of the fault.

[0082] In this embodiment of the application, the fault characteristic judgment criteria include:

[0083] The fault characteristic judgment criteria include at least one of the following: the first judgment criterion for a DC bus disconnection fault occurring on the high-voltage side of a DC transformer;

[0084] A second criterion for judging the occurrence of a single-pole grounding fault on the high-voltage side of a DC transformer;

[0085] And a third criterion for judging bipolar short-circuit faults on the high-voltage side of DC transformers.

[0086] In an optional embodiment, the first, second, and third 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, and verified through experiments and continuously optimized to ensure their accuracy and reliability. For example, for a DC bus open-circuit fault, the first judgment criterion can be set to determine a DC bus open-circuit fault when a sharp drop in the DC voltage on the high-voltage side is detected and the current is almost zero. For a single-pole grounding fault, the second judgment criterion can be set to determine a single-pole grounding fault when a significant decrease in the voltage of one pole on the high-voltage side is detected, while the voltage of the other pole remains unchanged or slightly increases, and an imbalance in the current is detected. For a bipolar short-circuit fault, the third judgment criterion can be set to determine a bipolar short-circuit fault when a sharp drop in the voltage of both the positive and negative poles on the high-voltage side is detected simultaneously, and the current increases significantly.

[0087] In an optional embodiment, when formulating fault characteristic 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 formulating fault characteristic judgment criteria, these special cases need to be fully considered, and corresponding measures should be taken for differentiation and identification.

[0088] In an optional embodiment, to improve the accuracy and efficiency of fault identification, the system can also employ various data processing and analysis techniques, such as signal processing, pattern recognition, and machine learning. These techniques can help the system identify fault characteristics more quickly and accurately, thereby promptly activating preset fault ride-through strategies and reducing the impact of faults on system stability and the overall operating efficiency of the photovoltaic 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, so that when new fault characteristics are detected in real time, the fault type can be quickly and accurately identified and corresponding fault ride-through strategies can be adopted.

[0089] Specifically, the voltage and current signals at the high-voltage side of the DC transformer are acquired in real time. , , , Fault identification on the high-voltage side of a DC transformer is performed based on voltage and current fault characteristics.

[0090] If criterion (1) is met, a DC bus disconnection fault occurs on the high-voltage side of the DC transformer, which is the first criterion in this application.

[0091] (1)

[0092] in, The current setting for the pole bus is typically set to 0.05 pu in engineering practice. The setpoint for the rate of change of DC bus current is typically set to 0.2 pu / 0.1 ms in engineering practice. It is a time variable.

[0093] 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.

[0094] (2)

[0095] in, This is the setpoint for the unbalanced voltage between the positive and negative DC buses, typically set to 0.5 pu in engineering practice. The low voltage setting for the DC bus is typically set to 0.3 pu in engineering applications.

[0096] 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.

[0097] (3)

[0098] in, The setpoint for the pole bus voltage is typically set to 0.3 pu in engineering practice. The setpoint for the rate of change of DC bus current is generally set to 0.2 pu / 0.1 ms in engineering.

[0099] It should be noted that once 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 determination result is a DC bus open circuit fault, a ride-through strategy for DC bus open circuit faults is activated; if the determination result is a single-pole grounding fault, a ride-through strategy for single-pole grounding faults is activated; if the determination result is a bipolar short circuit fault, a ride-through strategy for bipolar short circuit faults is activated. These ride-through strategies may include, but are not limited to, adjusting system parameters, switching to backup power, and isolating the fault area, in order to minimize the impact of the fault on system stability and the overall operating efficiency of the photovoltaic power plant.

[0100] In one optional embodiment, the fault ride-through strategy needs to consider factors such as the structural characteristics, operating principle, and fault type of the DC step-up transformer. For example, for a DC bus open circuit fault, the ride-through strategy might include quickly disconnecting the faulty line and activating the backup DC bus to ensure continuous power supply to the system. For a single-pole ground fault, the ride-through strategy might include adjusting system parameters, such as changing the grounding resistance value, to balance the voltage and current of the positive and negative poles and prevent further fault escalation. For a double-pole short-circuit fault, the ride-through strategy might include immediately disconnecting the power supply to the faulty area and isolating the faulty equipment to protect other normally operating equipment from being affected.

[0101] 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 techniques. 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. Simultaneously, big data analytics and cloud computing technologies can be used to mine and analyze historical fault data to discover patterns and trends in fault occurrence, providing a scientific basis for formulating fault ride-through strategies.

[0102] In an optional embodiment, a series of preventative maintenance measures can be implemented to improve system reliability and safety. For example, the DC step-up transformer can be inspected and maintained regularly to promptly identify and address potential faults. Simultaneously, 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 fault signs, enabling preventative measures to be taken before a fault occurs, thus avoiding its occurrence and escalation.

[0103] It should be noted that obtaining the first fault characteristics based on the first parameter provides crucial information for subsequent fault type identification and fault ride-through strategy formulation. Through accurate extraction and analysis of the first fault characteristics, the system can more quickly identify the fault type on the high-voltage side of the DC step-up transformer, thereby promptly initiating corresponding fault ride-through strategies and reducing the impact of the fault on the system. This rapid and accurate fault identification and ride-through capability is of great significance for ensuring system stability and the overall operating efficiency of the photovoltaic power plant. Furthermore, obtaining the first fault characteristics also helps the system perform fault early warning and preventative maintenance, further improving the system's reliability and safety.

[0104] S103, Preset fault traversal strategy: If the first fault characteristic of any fault type is obtained, the fault traversal strategy is activated.

[0105] In this embodiment, the preset fault ride-through strategy includes fault ride-through by designing the state judgment operation of the DC transformer.

[0106] In an optional embodiment, fault ride-through strategies may include, but are not limited to, adjusting system parameters, switching to backup power, isolating the faulty area, and restarting the DC transformer. The formulation of these strategies requires comprehensive consideration of factors such as the structural characteristics, operating principle, and fault type of the DC step-up transformer. For example, for a DC bus open circuit fault, the ride-through strategy might include quickly disconnecting the faulty line, activating the backup DC bus, and adjusting system parameters to ensure continuous power supply. For a single-pole ground fault, the ride-through strategy might include adjusting the grounding resistance value, balancing the voltage and current of the positive and negative poles to prevent further fault escalation, and monitoring the system status to determine if further measures are needed.

[0107] In an optional embodiment, for a bipolar short-circuit fault, the fault-crossing strategy may include immediately cutting off power to the faulty area, isolating the faulty equipment, activating backup protection equipment to protect other normally operating equipment from being affected, and restoring the system to normal operation as quickly as possible. When developing a fault-crossing strategy, it is necessary to fully consider the system's response and recovery capabilities under various fault conditions to ensure the effectiveness and reliability of the strategy.

[0108] 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 employed to optimize and control the fault ride-through process. Simultaneously, big data analytics and cloud computing technologies can be used to mine and analyze historical fault data to discover patterns and trends in fault occurrence, providing a scientific basis and direction for continuous optimization in the formulation of fault ride-through strategies.

[0109] In this embodiment of the application, initiating the fault-crossing strategy includes:

[0110] Once the first fault characteristic of any fault type is obtained, the fault traversal strategy is activated.

[0111] 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.

[0112] Determine whether the DC / DC converter experiences overcurrent blocking during this process.

[0113] In this embodiment of the application, initiating the fault-crossing strategy further includes:

[0114] If an overcurrent blockage occurs, the fault is considered transient once the DC voltage on the high-voltage side returns to its rated value.

[0115] Switch the MPPT to maximum power point tracking control mode, switch the DC step-up transformer to constant low voltage side DC voltage control mode. If the DC voltage recovers, it is determined to be a temporary fault. Switch the DC transformer to constant low voltage side DC voltage control mode, unlock the DC transformer again, and the system will automatically resume normal operation.

[0116] If the DC voltage on the high-voltage side cannot be restored after a set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

[0117] In this embodiment of the application, initiating the fault-crossing strategy further includes:

[0118] If no overcurrent blocking occurs, the fault is judged to be transient once the DC voltage on the high-voltage side returns to its rated value.

[0119] Switch the MPPT to maximum power point tracking control mode and switch the DC step-up transformer to low-voltage side DC voltage control mode. The system will then return to normal operation.

[0120] If the DC voltage on the high-voltage side cannot be restored after a set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

[0121] like Figure 3 As shown, the photovoltaic (PV) array is the source of DC power in the system. It consists of multiple photovoltaic panels that convert light energy into electrical energy. The MPPT controller ensures that the PV array always operates at its maximum power point under different light and temperature conditions. This maximizes the energy output of the PV array. The MPPT controller typically adjusts the operating voltage and current of the PV array to achieve optimal power output. The DC-DC boost converter boosts the lower voltage output from the PV array to a higher voltage level to facilitate subsequent inversion and grid connection operations. This converter can increase 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 needs to meet the grid's standard requirements, such as frequency, voltage, and phase, to ensure safe grid connection. The grid is the final point of contact for the power output from the grid-connected inverter. The grid is typically a three-phase AC system, and the AC power output from the inverter needs to be synchronized with the grid for stable grid connection.

[0122] like Figure 4 The diagram shows a topology of several parallel DC step-up transformers. This topology illustrates a design in a DC system where multiple DC step-up transformers are connected in parallel to increase the system's voltage level and transmission capacity. Each DC step-up transformer has independent input and output ports, and they are electrically isolated from each other to ensure stable operation. Figure 4In the diagram, it can be clearly seen that the high-voltage and low-voltage sides of each DC step-up transformer are connected to other parts of the system via conductors, forming an efficient energy transfer path. Furthermore, the topology diagram also illustrates the layout considerations for fault identification and ride-through methods in practical applications, ensuring that the system can quickly identify and implement ride-through measures in the event of a fault, maintaining the stable operation of the DC system.

[0123] In summary, this invention proposes a method for fault identification and fault ride-through on the high-voltage side of a DC transformer. The method obtains first parameters of the high-voltage side of the target DC step-up transformer. These first parameters include at least one of the following: positive and negative voltages and current on the high-voltage side of the DC step-up transformer. First fault characteristics are obtained based on these first parameters. These first fault characteristics are used to identify the fault type on the high-voltage side of the DC step-up transformer. A fault ride-through strategy is preset; if the first fault characteristics of any fault type are obtained, the fault ride-through strategy is activated. By utilizing local measurement information of the DC transformer, reliable identification and fault ride-through of DC faults in the collection system can be achieved, unaffected by photovoltaic output, thus improving the accuracy and efficiency of fault identification and providing a new approach and method for fault diagnosis of DC step-up transformers. Through a control-protection coordination approach, the accuracy and efficiency of fault identification are improved, providing a new approach and method for fault diagnosis of DC step-up transformers.

[0124] Example 2, in a preferred embodiment, provides detailed and specific implementable operational steps, such as... Figure 5 As shown, the voltage and current signals at the high-voltage side of the DC transformer are acquired in real time. , , , Fault identification on the high-voltage side of a DC transformer is performed based on voltage and current fault characteristics.

[0125] If criterion (1) is met, a DC bus disconnection fault occurs on the high-voltage side of the DC transformer, which is the first criterion in this application.

[0126] (1)

[0127] in, The current setting for the pole bus is typically set to 0.05 pu in engineering practice. The setpoint for the rate of change of DC bus current is generally set to 0.2 pu / 0.1 ms in engineering.

[0128] 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.

[0129] (2)

[0130] in, This is the setpoint for the unbalanced voltage between the positive and negative DC buses, typically set to 0.5 pu in engineering practice. The low voltage setting for the DC bus is typically set to 0.3 pu in engineering applications.

[0131] 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.

[0132] (3)

[0133] in, The setpoint for the pole bus voltage is typically set to 0.3 pu in engineering practice. The setpoint for the rate of change of DC bus current is generally set to 0.2 pu / 0.1 ms in engineering.

[0134] Furthermore, after a fault is detected on the DC high-voltage side, 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; it is determined whether the DC / DC converter experiences overcurrent blocking during this process.

[0135] If an overcurrent lockout occurs, wait for the high-voltage side DC voltage to return to its rated value. If so, it is considered 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, unlock the circuit, and the system will return to normal operation. If the high-voltage side DC voltage cannot be restored after the set time, it is considered a permanent fault. The DC / DC converter will be locked out, and the switches on both sides will be tripped immediately.

[0136] If no overcurrent blocking occurs, wait for the high-voltage side DC voltage to return to its rated value. If so, it is considered a transient fault. Switch the MPPT to the maximum power point tracking control mode and switch the DC step-up transformer to the low-voltage side DC voltage control mode. The system will then return to normal operation. If the high-voltage side DC voltage cannot be restored after the set time, it is considered a permanent fault. The DC / DC converter will be blocked, and both switches will be tripped immediately.

[0137] It should be noted that by analyzing the fault characteristics of the high-voltage side of the DC transformer and reliably detecting system fault conditions based on these characteristics, a fault ride-through strategy is initiated. This switches the DC converter from low-voltage side DC voltage control mode to open-loop rated frequency control mode, waiting for the high-voltage side DC voltage to recover. After a set time, based on the DC voltage recovery status, it is determined whether the fault is transient. The DC transformer then switches back to low-voltage side DC voltage control mode, the DC transformer is unlocked, and the system automatically resumes normal operation. This method is applicable to photovoltaic DC step-up collection systems. Through control and protection coordination, it improves the accuracy and efficiency of fault identification, providing a new approach and method for fault diagnosis of DC step-up transformers.

[0138] Example 3, this example also provides a DC transformer high-voltage side fault identification and ride-through system, including:

[0139] The data acquisition module is used to acquire the first parameters of the high-voltage side of the target DC step-up transformer;

[0140] The first parameter includes at least one of the following: the positive and negative voltage and current on the high-voltage side of the DC step-up transformer;

[0141] The feature acquisition module is used to acquire the first fault feature based on the first parameter;

[0142] The first fault characteristic is used to identify the fault type on the high-voltage side of the DC step-up transformer;

[0143] The strategy initiation module is used to preset the fault traversal strategy. If the first fault characteristic of any fault type is obtained, the fault traversal strategy is activated.

[0144] The above-mentioned unit modules can be embedded in the processor of the computer device in hardware form or independent of it, or they can be stored in the memory of the computer device in software form, so that the processor can call and execute the corresponding operations of the above modules.

[0145] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as follows. Figure 6As shown, the computer device includes a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. When executed by the processor, the computer program implements a method for identifying and traversing faults on the high-voltage side of a DC transformer. The display screen can be an LCD screen or an e-ink display screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0146] This embodiment also provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, it performs the following steps:

[0147] Obtain the first parameters of the high-voltage side of the target DC step-up transformer;

[0148] The first parameter includes at least one of the following: the positive and negative voltage and current on the high-voltage side of the DC step-up transformer;

[0149] The first fault characteristic is obtained based on the first parameter;

[0150] The first fault characteristic is used to identify the fault type on the high-voltage side of the DC step-up transformer;

[0151] A default fault traversal strategy is set up. If the first fault characteristic of any fault type is obtained, the fault traversal strategy is activated.

[0152] 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 it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

[0153] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can 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 this application can be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0154] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0155] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0156] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0157] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0158] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for fault identification and ride-through on the high-voltage side of a DC transformer, characterized in that, include: Obtain the first parameters of the high-voltage side of the target DC step-up transformer; The first parameter includes at least one of the following: the positive and negative voltages and current on the high-voltage side of the DC step-up transformer; The first fault characteristic is obtained based on 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 characteristic identifies the fault type on the high-voltage side of the DC step-up transformer using fault characteristic judgment criteria; The fault types on the high-voltage side of the DC step-up transformer include at least one of the following: A DC bus disconnection 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 double-pole short-circuit fault occurs on the high-voltage side of the DC transformer. A default fault traversal strategy is set up. If the first fault characteristic of any fault type is obtained, the fault traversal strategy is activated. The preset fault ride-through strategy includes fault ride-through by designing a state judgment operation of the DC transformer. The fault-crossing initiation strategy includes: If the fault ride-through strategy is activated, the MPPT will be switched to the output-side DC voltage control mode, and the DC converter will be switched from the low-voltage-side DC voltage control mode to the open-loop rated frequency control mode. Determine whether the DC / DC converter experiences overcurrent blocking during this process; the fault ride-through startup strategy also includes: If an overcurrent blockage occurs, the fault is considered transient once the DC voltage on the high-voltage side returns to its rated value. Switch the MPPT to maximum power point tracking control mode, switch the DC step-up transformer to constant low voltage side DC voltage control mode. If the DC voltage recovers, it is determined to be a temporary fault. Switch the DC transformer to constant low voltage side DC voltage control mode, unlock the DC transformer again, and the system will automatically resume normal operation. If the DC voltage on the high-voltage side cannot be restored after a set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped. The fault-crossing initiation strategy also includes: If no overcurrent blocking occurs, the fault is judged to be transient once the DC voltage on the high-voltage side returns to its rated value. Switch the MPPT to maximum power point tracking control mode and switch the DC step-up transformer to low-voltage side DC voltage control mode. The system will then return to normal operation. If the DC voltage on the high-voltage side cannot be restored after a set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

2. The method for fault identification and ride-through on the high-voltage side of a DC transformer as described in claim 1, characterized in that, The step of obtaining the first fault characteristic based on the first parameter includes: Establish a fault characteristic judgment standard based on the first parameter; Extract the first fault feature that meets the fault feature judgment criteria; The first fault feature includes at least one of the following: voltage fault features and current fault features corresponding to the occurrence of the fault.

3. The method for fault identification and ride-through on the high-voltage side of a DC transformer as described in 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 a DC transformer; A second criterion for judging the occurrence of a single-pole grounding fault on the high-voltage side of a DC transformer; And a third criterion for judging bipolar short-circuit faults on the high-voltage side of DC transformers.

4. A DC transformer high-voltage side fault identification and ride-through system, employing the DC transformer high-voltage side fault identification and ride-through method as described in any one of claims 1 to 3, characterized in that, include: The data acquisition module is used to acquire the first parameters of the high-voltage side of the target DC step-up transformer; The first parameter includes at least one of the following: the positive and negative voltages and current on the high-voltage side of the DC step-up transformer; The feature acquisition module is used to acquire the first fault feature based on 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 initiation module is used to preset the fault traversal strategy. If the first fault characteristic of any fault type is obtained, the fault traversal strategy is initiated. The preset fault ride-through strategy includes fault ride-through by designing a state judgment operation of the DC transformer. The fault-crossing initiation strategy includes: If the fault ride-through strategy is activated, the MPPT will be switched to the output-side DC voltage control mode, and the DC converter will be switched from the low-voltage-side DC voltage control mode to the open-loop rated frequency control mode. Determine whether the DC / DC converter experiences overcurrent blocking during this process; the fault ride-through startup strategy also includes: If an overcurrent blockage occurs, the fault is considered transient once the DC voltage on the high-voltage side returns to its rated value. Switch the MPPT to maximum power point tracking control mode, switch the DC step-up transformer to constant low voltage side DC voltage control mode. If the DC voltage recovers, it is determined to be a temporary fault. Switch the DC transformer to constant low voltage side DC voltage control mode, unlock the DC transformer again, and the system will automatically resume normal operation. If the DC voltage on the high-voltage side cannot be restored after a set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped. The fault-crossing initiation strategy also includes: If no overcurrent blocking occurs, the fault is judged to be transient once the DC voltage on the high-voltage side returns to its rated value. Switch the MPPT to maximum power point tracking control mode and switch the DC step-up transformer to low-voltage side DC voltage control mode. The system will then return to normal operation. If the DC voltage on the high-voltage side cannot be restored after a set time, it is judged as a permanent fault, the DC / DC converter is locked, and the switches on both sides are immediately tripped.

5. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the DC transformer high-voltage side fault identification and ride-through method according to any one of claims 1 to 3.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the DC transformer high-voltage side fault identification and ride-through method according to any one of claims 1 to 3.

Images