Overload protection methods, three-phase inverters and storage media

Abstract

This application relates to the field of power generation technology and provides an overload protection method, a three-phase inverter, and a computer-readable storage medium. The method includes: continuously acquiring the apparent power of each phase of the three-phase inverter during operation; comparing the maximum value of the apparent power of each phase with a preset threshold; incrementing a timing value corresponding to the preset threshold if the maximum value is greater than or equal to the preset threshold; decrementing the timing value if the maximum value is less than the preset threshold and the timing value corresponding to the preset threshold is greater than 0; and controlling all relays in the three-phase inverter to disconnect when the timing value reaches a corresponding preset protection duration, thereby stopping the three-phase inverter from operation. This method solves the problem of no single-phase overload protection in grid-connected and bypass conditions of three-phase energy storage inverters.

Description

Technical Field

[0001] This application belongs to the field of power generation technology, and in particular relates to an overload protection method, a three-phase inverter, and a computer-readable storage medium. Background Technology

[0003] In related technologies, three-phase energy storage inverters only detect overall three-phase overload (such as total three-phase power exceeding 1.5 times the rated power) under grid-connected and bypass conditions. If the apparent power of a single phase exceeds 1.5 times the rated power but the total three-phase power does not exceed the limit, the existing solution cannot trigger overload protection, which will directly lead to the relay burning out due to overload. Summary of the Invention

[0004] In view of this, this application provides an overload protection method, a three-phase inverter, and a computer-readable storage medium, which can solve the problem of no single-phase overload protection in the grid-connected and bypass conditions of a three-phase energy storage inverter.

[0005] In a first aspect, this application provides an overload protection method applied to a three-phase inverter, the three-phase inverter including an R-phase, an S-phase, and a T-phase, the method comprising: During the operation of the three-phase inverter, the apparent power of each phase of the three-phase inverter is continuously acquired; The maximum value of the apparent power of each phase is compared with a preset threshold. If the maximum value is greater than or equal to the preset threshold, the timing value corresponding to the preset threshold will be incremented. If the maximum value is less than the preset threshold, and the timing value corresponding to the preset threshold is greater than 0, then the timing value is decremented. When the timing value reaches the corresponding preset protection duration, all relays in the three-phase inverter are disconnected to stop the three-phase inverter from working.

[0006] Secondly, this application provides a three-phase inverter, including a memory and a processor. The memory stores a computer program, and the processor is used to call and run the computer program from the memory, so that the three-phase inverter performs the method provided in the first aspect above.

[0007] Thirdly, this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method provided in the first aspect.

[0008] Fourthly, this application provides a computer program product that, when running on a three-phase inverter, causes the three-phase inverter to perform the method provided in the first aspect above.

[0009] In the overload protection method provided in the first aspect above, during the operation of the three-phase inverter, the apparent power of each phase of the three-phase inverter is continuously acquired; the maximum value of the apparent power of each phase is compared with a preset threshold; if the maximum value is greater than or equal to the preset threshold, the timing value corresponding to the preset threshold is incremented; if the maximum value is less than the preset threshold, and the timing value corresponding to the preset threshold is greater than 0, the timing value is decremented; when the timing value reaches the corresponding preset protection duration, all relays in the three-phase inverter are controlled to disconnect, so that the three-phase inverter stops working. Thus, this solution, by selecting the maximum value of the apparent power of each phase of the three phases as the overload judgment benchmark, can realize the detection of overload conditions of any one phase of the three phases. Combined with the protection execution action of relay shutdown, it effectively solves the industry pain point of no single-phase overload protection in the grid-connected and bypass conditions of existing three-phase energy storage inverters, and avoids the risk of relay burnout due to single-phase overload not triggering the overall three-phase protection. Meanwhile, based on the comparison between the maximum apparent power of each phase and the preset threshold, this solution adopts a dynamic accumulation / decrease adjustment mechanism of timing values, which can effectively avoid the problems of protection false triggering and protection logic failure when the load power fluctuates frequently near the preset threshold.

[0010] It is understood that the beneficial effects of the second to fourth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a flowchart illustrating the overload protection method provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a three-phase inverter provided in the embodiments of this application. Detailed Implementation

[0013] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0014] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0015] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0016] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0017] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0018] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0019] First, the technical terms mentioned in the embodiments of this application will be explained.

[0020] A three-phase inverter is a power converter primarily used to convert direct current (DC) power into alternating current (AC) power. Its operating principle is based on power electronics technology and control principles; through effective circuit design and adjustment, it achieves the DC-to-AC conversion.

[0021] Grid connection: Grid connection refers to connecting the power generated by the three-phase inverter to the mains power grid, enabling both to jointly supply power to the load or feed power back to the grid. During grid connection, the three-phase inverter needs to ensure that its output voltage, frequency, and phase match the mains power grid.

[0022] Bypass: This is a core operating condition of the system and an important working mode on par with grid-connected, off-grid, and generator power supply. Simply put, the bypass mode means that the power grid directly supplies power to the load at the EPS port through the inverter's bypass circuit. The inverter's own DC / AC conversion module does not participate in power output and is in a "standby / bypass" state.

[0023] In actual operation, three-phase energy storage inverters only have dedicated off-grid overload protection logic under off-grid conditions, which can effectively detect and protect against single-phase overloads. However, under the two core operating conditions of grid connection and bypass, existing technologies do not have corresponding single-phase overload protection mechanisms; they only have overall overload protection logic based on the total three-phase power. When the system is in grid connection or bypass mode, if a single-phase apparent power exceeds 1.5 times the rated power due to severe three-phase load imbalance, but the total three-phase power still does not reach the preset three-phase overall overload protection threshold, the existing protection scheme cannot identify this type of single-phase overload fault and cannot trigger any protection action. This causes the relays responsible for the power supply path to be subjected to the large current impact of the single-phase overload for a long time, which can easily lead to overheating and burnout of the relays, causing system power supply failures or even equipment damage.

[0024] Figure 1 A flowchart of an overload protection method provided in an embodiment of this application is shown. This overload protection method is applied to a three-phase inverter, and is described in detail below: Step 101: During the operation of the three-phase inverter, continuously acquire the apparent power of each phase of the three-phase inverter.

[0025] Step 102: Compare the maximum value of the apparent power of each phase with a preset threshold.

[0026] Step 103: If the maximum value is greater than or equal to the preset threshold, the timing value corresponding to the preset threshold is incremented.

[0027] Step 104: If the maximum value is less than the preset threshold, and the timing value corresponding to the preset threshold is greater than 0, then the timing value is decremented.

[0028] Step 105: When the timing value reaches the corresponding preset protection duration, control all relays in the three-phase inverter to disconnect, so that the three-phase inverter stops working.

[0029] Apparent power refers to the independent apparent power of each of the R, S, and T phases continuously collected at the EPS port of the three-phase energy storage inverter. It is a core electrical parameter characterizing the actual load power of each phase of the three-phase inverter. Its collection results directly reflect the actual power consumption status of each phase load, providing data basis for overload judgment. Preset threshold refers to the apparent power protection threshold preset according to the rated power of the three-phase energy storage inverter and the overload protection requirements of different degrees. Timing value refers to the real-time timing parameter corresponding to the preset threshold, used to determine the duration of the single-phase overload state under the corresponding preset threshold. Its value is dynamically adjusted as the overload state continues or is relieved, and the timing values ​​corresponding to different preset thresholds do not interfere with each other and change independently.

[0030] The preset protection duration refers to the overload protection trigger time threshold that matches the preset threshold, representing the longest allowable duration for overload-triggered protection action. Relays refer to all core switching components in the power supply path of a three-phase energy storage inverter, specifically including off-grid relays, grid-connected relays, and generator relays. All are connected to the EPS port and are key components controlling the on / off state of the inverter's power supply path. Disconnecting all relays completely cuts off the inverter's power output path, achieving safe isolation of the equipment after an overload.

[0031] During the operation of the three-phase inverter under any working conditions such as grid connection, bypass, or off-grid, the apparent power of the three phases R, S, and T at the inverter's EPS port is continuously collected in real time to ensure that the acquired power data can accurately and synchronously reflect the dynamic changes of the load in each phase.

[0032] The collected three-phase independent apparent power values ​​are compared, and the maximum value is selected as the benchmark value for this overload judgment. This judgment method can detect overload conditions in any one of the three phases, solving the technical defect of traditional three-phase total power judgment that cannot identify single-phase unbalanced overloads, and ensuring that as long as any one of the three phases is overloaded, it can be accurately detected.

[0033] For example, firstly, the apparent power of each phase of the EPS port is sampled to obtain EpsLoadPowerAvg[R], EpsLoadPowerAvg[S], and EpsLoadPowerAvg[T]. Then, the maximum value among the above three-phase apparent power (EpsLoadPowerAvg[R], EpsLoadPowerAvg[S], and EpsLoadPowerAvg[T]) is taken as MAXEpsLoadPowerAvg.

[0034] The maximum value of the power of each phase is compared with a preset threshold. If the maximum value is greater than or equal to the preset threshold, it means that the system is in a single-phase overload state corresponding to the threshold. At this time, the timing value corresponding to the threshold is continuously increased, and the duration of the overload is recorded. If the maximum value is less than a certain preset threshold, it means that the overload state corresponding to the threshold has been released. At this time, if the timing value corresponding to the threshold is greater than 0, it is continuously decreased (and no longer changes after decreasing to 0) to avoid the accumulation of timing values ​​caused by instantaneous overload and prevent false triggering of protection.

[0035] The timing value corresponding to the preset threshold is monitored in real time. When the corresponding timing value increases to its matching preset protection duration, it indicates that the system is in a continuous overload state corresponding to the preset threshold. If operation continues, core components such as relays will burn out due to overload. At this time, a protection command is immediately triggered to control all relays in the three-phase inverter—off-grid, grid-connected, and generator—to disconnect simultaneously, completely cutting off all power supply paths to the inverter and stopping the three-phase inverter from working. This avoids further damage to the equipment caused by overload current and achieves reliable protection against single-phase overload.

[0036] Compared to directly triggering overload protection based solely on power thresholds, this application employs a design that accumulates timing values ​​corresponding to preset thresholds until a preset protection duration is reached before triggering overload protection. This effectively avoids false triggering of protection caused by instantaneous load fluctuations during the actual operation of three-phase energy storage inverters, significantly improving system stability and power supply continuity. In photovoltaic energy storage scenarios, the load connected to the inverter often experiences short-term apparent power exceeding the threshold due to motor starting, equipment start-up and shutdown, etc. Such instantaneous overloads are not true continuous faults. If only the power threshold is used as the trigger condition, it will lead to frequent protection activation and repeated relay switching, affecting not only the normal power supply to the load but also damaging core components such as relays. However, the timing triggering mechanism of this application only accumulates timing for overload states that continuously exceed the preset threshold. Instantaneous overloads will not trigger protection because the timing value has not reached the preset protection duration, accurately distinguishing between instantaneous load fluctuations and true continuous overload faults. The core of this application's design, which sets the timing value to gradually decrease to 0 rather than directly resetting it, is to solve the technical problem that overload protection cannot be triggered normally when the load fluctuates near the preset threshold. Specifically, when the load power fluctuates continuously around a preset threshold, it may briefly exceed the threshold and then briefly fall below it for a period shorter than the corresponding preset protection duration. If the timing value is directly reset to zero at this time, even if the average power of the load has consistently met the protection requirements, the timing value will be reset every time the power briefly drops, preventing the timing value from effectively accumulating to the corresponding preset protection duration. Consequently, overload protection will never be triggered, and the system will lose its ability to protect against such actual continuous overload conditions. However, by using a timing decrement method, when the load power is below the preset threshold, the timing value is gradually decremented and remains unchanged after reaching zero. This effectively preserves the accumulated timing information of the overload state, avoiding the problem of the timing value being directly reset to zero due to brief load drops, thus preventing it from accumulating to the preset protection duration. This ensures that even if the load fluctuates around the threshold, as long as its average power meets the protection requirements, the timing value can still gradually accumulate to the corresponding preset protection duration and trigger overload protection normally.

[0037] In some embodiments, the preset threshold includes a first preset threshold, a second preset threshold, and a third preset threshold, wherein the first preset threshold is less than the second preset threshold, and the second preset threshold is less than the third preset threshold; The preset protection duration includes a first preset protection duration, a second preset protection duration, and a third preset protection duration, wherein the first preset protection duration is longer than the second preset protection duration, and the second preset protection duration is longer than the third preset protection duration; The timing values ​​include a first timing value, a second timing value, and a third timing value; The first preset threshold, the first timing value, and the first preset protection duration correspond to each other; The second preset threshold, the second timing value, and the second preset protection duration correspond to each other; The third preset threshold, the third timing value, and the third preset protection duration correspond to each other.

[0038] In this embodiment, the preset threshold, timing value, and preset protection duration are all divided into three corresponding levels: the first level, the second level, and the third level, with parameters within each level corresponding one-to-one. The preset thresholds are categorized from low to high overload severity as a first preset threshold, a second preset threshold, and a third preset threshold, satisfying the relationship that the first preset threshold < the second preset threshold < the third preset threshold. In this scheme, these three preset thresholds specifically correspond to 1.2 times, 1.3 times, and 1.5 times the rated power of the three-phase inverter, respectively. This progressively increasing threshold setting accurately distinguishes between light, medium, and heavy single-phase overload conditions. For example, if the rated power of the three-phase inverter is 10kW, then the first preset threshold is 1.2 times the rated power (12kW), the second preset threshold is 1.3 times the rated power (13kW), and the third preset threshold is 1.5 times the rated power (15kW).

[0039] The timing value serves as the overload duration recording parameter corresponding to each preset threshold. It is synchronously divided into a first timing value, a second timing value, and a third timing value. The first timing value is only matched and linked with the first preset threshold, the second timing value is only matched and linked with the second preset threshold, and the third timing value is only matched and linked with the third preset threshold. The three are independent timing parameters with an initial value of 0. Their incrementing and decrementing adjustment process is only affected by the overload judgment result of the corresponding preset threshold and will not interfere with the timing logic of another level due to the change of the timing value of one level.

[0040] The preset protection duration serves as the trigger time threshold for each level of overload protection. It is divided into three preset protection durations: Time1 (first preset protection duration), Time2 (second preset protection duration), and Time3 (third preset protection duration). The three durations satisfy the relationship that the first preset protection duration > the second preset protection duration > the third preset protection duration. The gradient decreasing duration setting is matched with the gradient increasing power threshold, so that the higher the overload level, the faster the protection triggers.

[0041] In some embodiments, comparing the maximum value of the apparent power of each phase with a preset threshold includes: comparing the maximum value with the first preset threshold, the second preset threshold, and the third preset threshold, respectively; Wherein, if the maximum value is greater than or equal to the first preset threshold, the first timing value is incremented; if the maximum value is less than the first preset threshold, and the first timing value is greater than 0, the first timing value is decremented. If the maximum value is greater than or equal to the second preset threshold, the second timing value is incremented; if the maximum value is less than the second preset threshold, and the second timing value is greater than 0, the second timing value is decremented. If the maximum value is greater than or equal to the third preset threshold, the third timing value is incremented; if the maximum value is less than the third preset threshold, and the third timing value is greater than 0, the third timing value is decremented. When the timing value reaches the corresponding preset protection duration, controlling all relays in the three-phase inverter to disconnect includes: When the first timing value reaches the first preset protection duration, control all relays in the three-phase inverter to disconnect; When the second timing value reaches the second preset protection duration, control all relays in the three-phase inverter to disconnect; When the third timing value reaches the third preset protection duration, all relays in the three-phase inverter are disconnected.

[0042] Understandably, the first preset threshold, first timing value, and first preset protection duration constitute the first protection level, specifically for detecting and protecting against light overload conditions; the second preset threshold, second timing value, and second preset protection duration constitute the second protection level, specifically for detecting and protecting against medium overload conditions; and the third preset threshold, third timing value, and third preset protection duration constitute the third protection level, specifically for detecting and protecting against heavy overload conditions. A longer protection trigger duration is matched for light overload conditions to avoid false triggering of protection due to slight and brief load fluctuations, ensuring the stability of system operation. A shortest protection trigger duration is matched for heavy overload conditions, enabling fault identification and protection actions in a very short time, preventing core components such as relays from burning out due to prolonged exposure to heavy overload current. Simultaneously, the independent parameter design of each level ensures that the three-phase inverter can simultaneously monitor light, medium, and heavy overload states during operation, and any protection level can independently execute timing and protection actions when the trigger conditions are met.

[0043] The first, second, and third timing values ​​are independently determined based on their respective first, second, and third preset protection durations. The determination process at each level is independent of any order or interdependence. Once any timing value accumulates to its corresponding preset protection duration, an overload protection action is triggered independently, directly controlling all relays in the three-phase inverter to simultaneously disconnect, causing the three-phase inverter to stop operating. In other words, when the first timing value corresponding to a minor overload reaches the first preset protection duration, protection can be triggered independently; when the second timing value corresponding to a moderate overload reaches the second preset protection duration, protection can be triggered independently; and when the third timing value corresponding to a severe overload reaches the third preset protection duration, protection can be triggered preferentially without being affected by other levels. Furthermore, because the preset protection duration for severe overloads is shorter, a faster fault response can be achieved.

[0044] For example, if the rated power of a three-phase inverter is 10kW, then the first preset threshold is 1.2 times the rated power (12kW), the second preset threshold is 1.3 times the rated power (13kW), and the third preset threshold is 1.5 times the rated power (15kW). The corresponding first preset protection duration is 3s, the second preset protection duration is 2s, and the third preset protection duration is 1s. The initial values ​​of the first, second, and third timing values ​​are all 0, and each timing value is adjusted independently based on the overload judgment result of the corresponding preset threshold. When the maximum value of the three-phase apparent power continuously exceeds the third preset threshold, the third timing value will first reach the third preset protection duration, triggering the disconnection of all relays in the three-phase inverter. If a software error occurs, causing the relays not to actually disconnect, since the three levels of protection operate independently, the second timing value will reach the second preset protection duration over time, triggering the disconnection of all relays in the three-phase inverter, ensuring timely relay shutdown in case of single-phase overload.

[0045] In some embodiments, the method further includes: When the timing value reaches the corresponding preset protection duration, a set error signal is sent to the communication bus of the parallel system to disconnect all relays of all three-phase inverters in the parallel system, wherein the load of each three-phase inverter in the parallel system is balanced.

[0046] In this embodiment, each three-phase inverter in the parallel system independently performs the same overload protection judgment operation as a single unit. This involves continuously collecting the apparent power of each phase, selecting the maximum value, comparing this maximum value with first, second, and third preset thresholds, and adjusting the first, second, and third timing values ​​accordingly based on the comparison results. When any timing value of any three-phase inverter in the parallel system reaches its corresponding preset protection duration, the synchronous protection process of the parallel system will be initiated. The three-phase inverter that triggered the protection will immediately send a set error signal to the communication bus of the parallel system.

[0047] The set error signal is transmitted on the communication bus of the parallel system in the form of a fast event. When the host of the parallel system detects the set error signal, it will immediately send a unified bus system error flag to the parallel bus to ensure that all three-phase inverters in the parallel system can receive the flag synchronously. After receiving the bus system error flag, all inverters will simultaneously shut down all their own relays to realize the synchronous execution of protection actions of all devices in the parallel system.

[0048] In a parallel system, the load ports of each three-phase inverter are interconnected. Under normal operating conditions, the overall load of the system is shared equally by all the three-phase inverters in the parallel system. When a single three-phase inverter triggers its overload protection, it doesn't mean that only that device is overloaded; rather, the entire parallel system is close to being overloaded. The individual inverter simply completes its timer accumulation and triggers its protection first. If only the relay of the single inverter that triggered the protection is turned off, the load it originally carried will be transferred to the remaining three-phase inverters in the parallel system. This causes a sudden increase in the load pressure on the remaining three-phase inverters, further exacerbating the overload. This not only fails to achieve the desired overload protection but also expands the fault range, causing damage to more equipment. Therefore, only by using the synchronous communication mechanism of the parallel bus to simultaneously turn off the relays of all three-phase inverters can the power output path of the parallel system be completely cut off, avoiding secondary overloads caused by load transfer and truly achieving overall overload protection for the parallel system.

[0049] In some embodiments, the method further includes: After the three-phase inverter stops working, in response to the restart command, the three-phase inverter is restarted according to the new three-phase load configuration information.

[0050] When a three-phase inverter triggers overload protection after any timing value reaches the corresponding preset protection duration, disconnecting all relays and stopping operation, system recovery cannot be completed directly. The user must first adjust and optimize the three-phase load configuration before responding to the restart command and restarting the inverter according to the new three-phase load configuration information. The reason for requiring a restart based on the new three-phase load configuration is that the inverter's overload protection trigger essentially indicates a continuous single-phase overload in the system. The root cause of this fault is an imbalance in the current three-phase load configuration, or a single-phase load exceeding the equipment's rated load capacity. By requiring the user to specifically adjust the three-phase load configuration before performing the restart, it ensures that the three-phase load connected to the inverter after restarting meets the equipment's rated load requirements, avoiding repeated triggering of protection actions and guaranteeing stable and safe operation of the inverter after restarting.

[0051] In some embodiments, the method further includes: If the maximum value is less than the preset threshold, and the timing value is equal to 0, then the timing value remains unchanged.

[0052] In this embodiment of the application, when the maximum power of each phase is less than the corresponding preset threshold, it indicates that the system has released the overload state corresponding to the threshold. If the corresponding timing value is 0, it means that the system has not generated an overload timing accumulation at this level before, and there is no overload duration record at this level. In this case, there is no need to perform any operation on the timing value, and it is sufficient to keep its 0 value unchanged.

[0053] Optionally, continuously acquiring the apparent power of each phase of the three-phase inverter includes: The apparent power of each phase of the three-phase inverter is continuously sampled at the emergency power EPS port.

[0054] The emergency power supply (EPS) port is the common convergence node for all power supply paths of the three-phase inverter, including off-grid, grid-connected, and generator power supplies. It is also the core connection port between the inverter and the load. The apparent power data of this port can accurately reflect the actual load power status of each phase of the inverter. Using this as a sampling point ensures that the collected power parameters are highly consistent with the actual operating conditions from the data source, avoiding overload judgment distortion caused by sampling point deviation. At the same time, continuous sampling of the apparent power of each phase of the three-phase inverter can synchronously capture the dynamic changes of the apparent power of each phase and promptly identify overload trends in any phase.

[0055] In some embodiments, controlling all relays in the three-phase inverter to disconnect includes controlling the off-grid relay, grid-connected relay, and generator relay in the three-phase inverter to disconnect.

[0056] In this embodiment, after the overload protection is triggered, all off-grid relays, grid-connected relays, and generator relays that synchronously control the three-phase inverter are disconnected. This cuts off the power supply path for all operating conditions of the three-phase inverter, achieving complete electrical isolation between the inverter and the load, grid, and generator. This fundamentally eliminates the continuous impact of overload current on the equipment, preventing relays, inverter core modules, and other components from burning out or being permanently damaged due to prolonged overload current. The off-grid relay, grid-connected relay, and generator relay correspond to the power on / off control of the three-phase inverter under off-grid, grid-connected / bypass, and generator-powered operating conditions, respectively.

[0057] As can be seen from the above, in this application, by selecting the maximum apparent power of each of the three phases as the overload judgment benchmark, the overload condition of any one of the three phases can be detected. Combined with the protection action of relay shutdown, this effectively solves the industry pain point of the lack of single-phase overload protection in the grid-connected and bypass conditions of three-phase energy storage inverters in existing technologies, and avoids the risk of relay burnout due to single-phase overload failing to trigger the overall three-phase protection. Furthermore, based on the comparison results of the maximum apparent power of each phase with the preset threshold, this solution adopts a dynamic accumulation / decrease adjustment mechanism of the timing value, which can effectively avoid the problems of protection false triggering and protection logic failure when the load power fluctuates frequently around the preset threshold.

[0058] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0059] Figure 2 This is a schematic diagram of a three-phase inverter provided in one embodiment of this application. Figure 2 As shown, the three-phase inverter 2 in this embodiment includes: at least one processor 20 ( Figure 2 (Only one is shown in the diagram), memory 21, and computer program 22 stored in the memory 21 and executable on at least one processor 20. When the processor 20 executes the computer program 22, it causes the three-phase inverter to perform the overload protection method described above.

[0060] The aforementioned three-phase inverter 2 may include, but is not limited to, a processor 20 and a memory 21. Those skilled in the art will understand that... Figure 2 This is merely an example of a three-phase inverter 2 and does not constitute a limitation on the three-phase inverter 2. It may include more or fewer components than shown in the figure, or combine certain components, or different components, such as input / output devices, network access devices, etc.

[0061] The processor 20 may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0062] In some embodiments, the aforementioned memory 21 may be an internal storage unit of the three-phase inverter 2, such as a hard disk or memory of the three-phase inverter 2. In other embodiments, the aforementioned memory 21 may be an external storage device of the three-phase inverter 2, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the three-phase inverter 2. Furthermore, the aforementioned memory 21 may include both internal storage units and external storage devices of the three-phase inverter 2. The aforementioned memory 21 is used to store operating systems, application programs, bootloaders, data, and other programs, such as the program code of the aforementioned computer programs. The aforementioned memory 21 may also be used to temporarily store data that has been output or will be output.

[0063] It should be noted that the information interaction and execution process between the above-mentioned devices / units are based on the same concept as the method embodiments of this application. For details on their specific functions and technical effects, please refer to the method embodiments section, and they will not be repeated here.

[0064] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the above device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0065] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in the various method embodiments described above.

[0066] This application provides a computer program product that, when run on a three-phase inverter, causes the three-phase inverter to execute the steps described in the various method embodiments above.

[0067] If the integrated units described above are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a three-phase inverter, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electrical carrier signals or telecommunication signals.

[0068] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0069] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0070] In the embodiments provided in this application, it should be understood that the disclosed apparatus / network devices and methods can be implemented in other ways. For example, the apparatus / network device embodiments described above are merely illustrative. For instance, the division of modules or units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0071] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0072] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An overload protection method, characterized in that, Applied to a three-phase inverter, the three-phase inverter comprising an R-phase, an S-phase, and a T-phase, the method includes: During the operation of the three-phase inverter, the apparent power of each phase of the three-phase inverter is continuously acquired; The maximum value of the apparent power of each phase is compared with a preset threshold. If the maximum value is greater than or equal to the preset threshold, the timing value corresponding to the preset threshold will be incremented. If the maximum value is less than the preset threshold, and the timing value corresponding to the preset threshold is greater than 0, then the timing value is decremented. When the timing value reaches the corresponding preset protection duration, all relays in the three-phase inverter are disconnected to stop the three-phase inverter from working.

2. The method as described in claim 1, characterized in that, The preset threshold includes a first preset threshold, a second preset threshold, and a third preset threshold, wherein the first preset threshold is less than the second preset threshold, and the second preset threshold is less than the third preset threshold; The preset protection duration includes a first preset protection duration, a second preset protection duration, and a third preset protection duration, wherein the first preset protection duration is longer than the second preset protection duration, and the second preset protection duration is longer than the third preset protection duration; The timing values ​​include a first timing value, a second timing value, and a third timing value; The first preset threshold, the first timing value, and the first preset protection duration correspond to each other; The second preset threshold, the second timing value, and the second preset protection duration correspond to each other; The third preset threshold, the third timing value, and the third preset protection duration correspond to each other.

3. The method as described in claim 2, characterized in that, The step of comparing the maximum value of the apparent power of each phase with a preset threshold includes: comparing the maximum value with the first preset threshold, the second preset threshold and the third preset threshold respectively; Wherein, if the maximum value is greater than or equal to the first preset threshold, the first timing value is incremented; if the maximum value is less than the first preset threshold, and the first timing value is greater than 0, the first timing value is decremented. If the maximum value is greater than or equal to the second preset threshold, the second timing value is incremented; if the maximum value is less than the second preset threshold, and the second timing value is greater than 0, the second timing value is decremented. If the maximum value is greater than or equal to the third preset threshold, the third timing value is incremented; if the maximum value is less than the third preset threshold, and the third timing value is greater than 0, the third timing value is decremented. When the timing value reaches the corresponding preset protection duration, controlling all relays in the three-phase inverter to disconnect includes: When the first timing value reaches the first preset protection duration, control all relays in the three-phase inverter to disconnect; When the second timing value reaches the second preset protection duration, control all relays in the three-phase inverter to disconnect; When the third timing value reaches the third preset protection duration, all relays in the three-phase inverter are disconnected.

4. The method as described in claim 1, characterized in that, The method further includes: When the timing value reaches the corresponding preset protection duration, a set error signal is sent to the communication bus of the parallel system to disconnect all relays of all three-phase inverters in the parallel system, wherein the load of each three-phase inverter in the parallel system is balanced.

5. The method as described in claim 1, characterized in that, The method further includes: After the three-phase inverter stops working, in response to the restart command, the three-phase inverter is restarted according to the new three-phase load configuration information.

6. The method as described in claim 1, characterized in that, The method further includes: If the maximum value is less than the preset threshold, and the timing value is equal to 0, then the timing value remains unchanged.

7. The method as described in claim 1, characterized in that, The continuous acquisition of the apparent power of each phase of the three-phase inverter includes: The apparent power of each phase of the three-phase inverter is continuously sampled at the emergency power EPS port.

8. The method as described in claim 1, characterized in that, The control of disconnecting all relays in the three-phase inverter includes: controlling the disconnection of the off-grid relay, the grid-connected relay, and the generator relay in the three-phase inverter.

9. A three-phase inverter, characterized in that, The device includes a memory and a processor, wherein the memory stores a computer program, and the processor is configured to call and run the computer program from the memory, causing the three-phase inverter to perform the method as described in any one of claims 1-8.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 8.

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