Fault detection method, device, system and equipment and storage medium

Abstract

The invention provides a fault detection method, device and system, equipment and a storage medium. For the three-phase power system, the bus voltage of the unit of the three-phase power system can be monitored, after the ripple frequency corresponding to the bus voltage is detected to be the fault frequency for the first time, the operation frequency of the unit of the three-phase power system can be controlled to be increased to the target frequency, and the fault type of the three-phase power system is determined according to the bus voltage after frequency increasing. According to the invention, no extra hardware sensor or protection module is needed, the cost and hardware complexity of a three-phase power system can be greatly reduced, fault points are reduced, and the reliability is improved; besides, the open-phase fault and the three-phase imbalance fault can be well and accurately distinguished through frequency raising verification, shutdown or protection leakage caused by misjudgment of an existing method is avoided, the unit operation efficiency is improved, and the power supply reliability and the operation safety of the high-power air conditioner equipment can be remarkably improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of three-phase power supply, and in particular to a fault detection method, device, system, equipment and storage medium. BACKGROUND

[0002] In a high-power air conditioning equipment, three-phase alternating current power supply is the core power source of the compressor and the fan, and the stability of the power supply directly determines the operation efficiency and service life of the equipment. However, in actual operation, the three-phase power supply system often produces two typical faults: open-phase fault and three-phase unbalanced fault due to power line faults, uneven load distribution or power grid fluctuations.

[0003] The open-phase fault refers to the complete loss of a phase voltage or current, which causes the motor to run under two-phase power supply conditions, thereby causing a sharp increase in current, a sudden drop in torque, and even causing the motor to burn out. The three-phase unbalanced fault is manifested as a difference in the amplitude and phase of the three-phase voltage or current, which leads to a decrease in motor efficiency, abnormal temperature rise and unstable operation.

[0004] In related technologies, the open-phase fault is usually judged by detecting whether the ripple frequency of the bus voltage is 100Hz. However, this method has a significant defect: when the power grid has a three-phase unbalanced fault, the ripple frequency of the bus voltage may also approach or reach 100Hz, which is easy to misjudge the three-phase unbalanced fault as an open-phase fault, thereby causing unnecessary shutdown, or failing to handle the three-phase unbalanced fault in time, leading to capacitor damage, which seriously threatens the safety and stability of the unit and its service life. SUMMARY

[0005] In view of this, in order to solve the technical problem that the open-phase fault and the three-phase unbalanced fault in the three-phase power supply system are easily misjudged in related technologies, the present disclosure provides a fault detection method, device, system, equipment and storage medium.

[0006] According to a first aspect of an embodiment of the present disclosure, a fault detection method of a three-phase power supply system is provided, and the fault detection method comprises: monitoring a bus voltage of a unit of the three-phase power supply system; after detecting for the first time that the ripple frequency corresponding to the bus voltage is a fault frequency, controlling the operation frequency of the unit of the three-phase power supply system to be increased to a target frequency; determining the fault type of the three-phase power supply system based on the bus voltage at the target frequency.

[0007] In an optional implementation, The determination of the fault type of the three-phase power supply system based on the bus voltage at the target frequency comprises: monitoring a rising edge signal of the bus voltage; If the rising edge signal is monitored for M consecutive times, a time difference between a corresponding time of the next rising edge signal and a corresponding time of the current rising edge signal is calculated; wherein M is a positive integer greater than or equal to 3 and less than or equal to 7; If it is determined that the time difference is in a first time range, the fault type is determined to be a three-phase unbalanced fault.

[0008] In an optional embodiment, After it is determined that the time difference is in the first time range, the condition for determining the fault type to be a three-phase unbalanced fault includes: determining that a phase difference change rate of at least two phase currents of the three-phase current of the three-phase power system is less than or equal to a first set change rate; and / or, determining that an attenuation rate of the bus voltage in a period corresponding to the fault frequency is in a first attenuation rate range.

[0009] In an optional embodiment, The fault detection method includes: If it is determined that the time difference is in a second time range, a single-phase loss waveform feature is determined; wherein a minimum value of the second time range is greater than a maximum value of the first time range; If it is determined that the single-phase loss waveform feature is detected for N times within a first time range, the fault type is determined to be a single-phase loss fault.

[0010] In an optional embodiment, After it is determined that the single-phase loss waveform feature occurs for N times within the first time range, the condition for determining the fault type to be a single-phase loss fault includes: determining that a phase difference change rate of any two phase currents of the three-phase current of the three-phase power system is greater than or equal to a second set change rate; and / or, determining that an attenuation rate of the bus voltage in a period corresponding to the fault frequency is in a second attenuation rate range.

[0011] In an optional embodiment, The fault detection method includes: If the fault type is determined to be a three-phase unbalanced fault, an operating frequency of a unit of the three-phase power system is restored to a reference frequency; Based on a peak-to-peak value of the bus voltage at the reference frequency and a set threshold, an operating frequency of a unit of the three-phase power system is controlled.

[0012] In an optional embodiment, The control of the operating frequency of the unit of the three-phase power system based on the peak-to-peak value of the bus voltage at the reference frequency and the set threshold includes: If the peak-to-peak value is less than or equal to the set threshold value, control the unit of the three-phase power system to maintain the current frequency operation.

[0013] In an optional embodiment, The control of the operating frequency of the unit of the three-phase power system based on the peak-to-peak value of the bus voltage at the reference frequency and the set threshold value comprises: If the peak-to-peak value is greater than the set threshold value, reduce the operating frequency of the unit of the three-phase power system at a set frequency reduction gradient until the peak-to-peak value is less than or equal to the set threshold value, or until the operating frequency of the unit of the three-phase power system is reduced to the minimum safe frequency.

[0014] In an optional embodiment, The control of the operating frequency of the unit of the three-phase power system based on the peak-to-peak value of the bus voltage at the reference frequency and the set threshold value comprises: After the operating frequency of the unit of the three-phase power system is reduced to the minimum safe frequency, if the peak-to-peak value is greater than the set threshold value, control the unit of the three-phase power system to shut down.

[0015] In an optional embodiment, The fault detection method comprises: If it is determined that the fault type is an open-phase fault, determine that after H times of the open-phase fault occurs within a second time length, control the unit of the three-phase power system to shut down; wherein H is a positive integer greater than or equal to 1800 and less than or equal to 2000.

[0016] In an optional embodiment, The target frequency is the maximum allowable operating frequency of the unit of the three-phase power system at the current ambient temperature.

[0017] According to a second aspect of the embodiments of the present disclosure, a fault detection device is provided, which is applied to a three-phase power system, and the fault detection device comprises: A monitoring module is configured to monitor a bus voltage of a unit of the three-phase power system. A control module is configured to, after detecting for the first time that a ripple frequency corresponding to the bus voltage is a fault frequency, control an operating frequency of the unit of the three-phase power system to increase to a target frequency. A determination module is configured to determine a fault type of the three-phase power system based on the bus voltage at the target frequency.

[0018] According to a third aspect of the embodiments of the present disclosure, a three-phase power system is provided, which is used to implement the fault detection method according to any one of the first aspect.

[0019] According to a fourth aspect of the embodiments of the present disclosure, an electronic device is provided, which comprises a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus; the memory is configured to store a computer program; and the processor is configured to execute the computer program to implement the fault detection method according to any one of the first aspect.

[0020] According to a fifth aspect of the embodiments of the present disclosure, a storage medium is provided, which stores a computer program, and the computer program is executed by a processor to implement the fault detection method according to any one of the first aspect.

[0021] The technical solution provided by the embodiments of the present disclosure can have the following beneficial effects: In the present disclosure, for a three-phase power system, the bus voltage of the unit of the three-phase power system can be monitored, and after it is first detected that the bus voltage corresponds to a fault frequency (for example, 100 Hz), the operating frequency of the unit of the three-phase power system can be controlled to increase to a target frequency (for example, the maximum allowable operating frequency of the unit of the three-phase power system under the current environmental temperature), and the fault type of the three-phase power system can be determined according to the bus voltage after the increase (i.e., the bus voltage under the target frequency). The present disclosure does not require additional hardware sensors or protection modules, can greatly reduce the cost and hardware complexity of the three-phase power system, reduce the fault points, and improve the reliability; in addition, the present disclosure can accurately distinguish between open-phase faults and three-phase unbalanced faults through "frequency increase verification", avoid shutdown or protection failure caused by misjudgment of the existing method, improve the operation efficiency of the unit, and can significantly improve the power supply reliability and operation safety of high-power air conditioning equipment.

[0022] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present disclosure and, together with the specification, serve to explain the principles of the present disclosure.

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0025] One or more embodiments are illustrated by way of example in the drawings and are described herein in connection with the embodiments presented. The embodiments described herein are not intended to be limited to the exemplary designs described herein, but are to serve as the basis for claimable subject matter, and a variety of embodiments are intended to be potentially covered herewith. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not restrictive.

[0026] Figure 1 is a flowchart of a fault detection method according to an example embodiment.

[0027] Figure 2 is a flowchart of a fault detection method according to another example embodiment.

[0028] Figure 3 is a flowchart of a fault detection method according to another example embodiment.

[0029] Figure 4 is a flowchart of a fault detection method according to another example embodiment.

[0030] Figure 5 is a schematic diagram of an open-phase fault according to an example embodiment.

[0031] Figure 6 is a schematic diagram of a three-phase unbalanced fault according to an example embodiment.

[0032] Figure 7 is a block diagram of a fault detection apparatus according to an example embodiment.

[0033] Figure 8 is a block diagram of an electronic device according to an example embodiment. DETAILED DESCRIPTION

[0034] In order to make the purposes, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0035] The following disclosure provides many different embodiments, or examples, for implementing different aspects, embodiments and / or configurations of the present application. For simplicity, the present disclosure focuses on the primary components of the present application with reference to a limited number of embodiments corresponding to the drawings. It should be understood, however, that the present application can include any number of additional or other components, whether such components are illustrated in the drawings or not. Furthermore, the disclosure of a specific number of embodiments or examples within the present application should not be construed as limiting the present application to those specific embodiments or examples. In fact, a specific number of embodiments or examples are not provided so as to not limit the present application and to allow a person of ordinary skill in the art to understand the scope of the present application.

[0036] For ease of description, spatial relative terms can be used herein to describe the relative position relationship or movement condition of one element or feature with respect to another element or feature as shown in the drawings, such as "inner", "outer", "inboard", "outboard", "under", "below", "on", "above", "front", "back", and the like. Such spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the drawings. For example, if the device in the drawings is turned over or reversed, or the orientation of the device is changed, the indicative directions will also change accordingly, for example: the element described as "under" or "below" another element or feature will be subsequently oriented as "above" or "above" another element or feature. Therefore, the example term "below" can include both the up and down positions. The device can be additionally oriented (rotated 90 degrees or in other directions) and the spatial relative relationship descriptors used herein are interpreted accordingly.

[0037] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concepts of the present application in a schematic manner, and only show the components related to the present application in the diagrams, not drawn according to the number, shape and size of the components in actual implementation. The actual implementation of each component can be a random change, and the component layout pattern can be more complex.

[0038] The embodiments of the present application will be described below with reference to the drawings and preferred embodiments, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure in the specification. The present application can also be implemented or applied by other different specific embodiments, and each detail in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be understood that the preferred embodiments are only for illustration of the present application, and are not intended to limit the protection scope of the present application.

[0039] In order to solve the technical problems of misjudgment of open-phase fault and three-phase unbalanced fault in three-phase electric system in the related art, the present disclosure provides a fault detection method, device, system, equipment and storage medium.

[0040] In the present disclosure, for a three-phase power system, the bus voltage of the unit of the three-phase power system can be monitored, and after the first time the ripple frequency corresponding to the bus voltage is detected as a fault frequency (for example, 100 Hz), the operating frequency of the unit of the three-phase power system can be controlled to increase to a target frequency (for example, the maximum allowable operating frequency of the unit of the three-phase power system at the current ambient temperature), and the fault type of the three-phase power system can be determined according to the bus voltage after the increase (i.e., the bus voltage at the target frequency). The present disclosure can greatly reduce the cost and hardware complexity of the three-phase power system without additional hardware sensors or protection modules, while reducing the fault points and improving the reliability. In addition, the present disclosure can accurately distinguish between open-phase faults and three-phase imbalance faults through "frequency increase verification", avoiding shutdown or missed protection caused by misjudgment of existing methods, improving the operation efficiency of the unit, and significantly improving the power supply reliability and operation safety of high-power air conditioning equipment.

[0041] In one example embodiment, referring to Figure 1 、 Figure 5 and Figure 6 , a fault detection method for a three-phase power system is provided. The three-phase power system can be a power supply system of an air conditioning equipment, or a power supply system of other equipment, which is not limited. In this embodiment, the fault detection method comprises: S110, monitoring the bus voltage of the unit of the three-phase power system; S120, after the first time the ripple frequency corresponding to the bus voltage is detected as a fault frequency, controlling the operating frequency of the unit of the three-phase power system to increase to a target frequency; S130, determining the fault type of the three-phase power system based on the bus voltage at the target frequency.

[0042] In step S110, it should be noted that in the three-phase power system, when the input three-phase power supply is normal, the ripple frequency of the bus voltage is generally a certain fixed frequency (for example, 300 Hz). The fixed frequency is related to the grid frequency of the three-phase power supply. When the input power supply is open-phase or three-phase imbalance and the unit is in low-medium frequency operation, three-phase imbalance and open-phase may exhibit the same characteristics, at this time the ripple frequency of the bus voltage is a fault frequency (for example, 100 Hz), and presents a monotone decreasing state, as shown in Figure 5 When the unit is overloaded, if it is three-phase imbalance, at this time a small wave head (a small wave peak of short-time voltage rise / fall) of the waveform will appear, as shown in Figure 6 .

[0043] Based on this, in this step, the bus voltage of the unit of the three-phase power system can be monitored in real time so as to determine whether the open-phase fault or the three-phase unbalance fault occurs. The monitoring of the bus voltage can be realized by a voltage transformer, for example, the electromagnetic voltage transformer is used to convert the high-voltage bus voltage into a low-voltage signal, and then the real-time sampling processing is performed by a data acquisition system. Of course, the monitoring of the bus voltage can also be realized by other manners, and no limitation is made herein.

[0044] In step S120, the fault frequency can be determined according to actual conditions. In general, for a 50Hz or 60Hz power grid, the fault frequency can be 100Hz, of course, it can also be near 100Hz, for example, the fault frequency can be greater than or equal to 95Hz and less than or equal to 105Hz, so as to reduce the judgment error and improve the reliability of the judgment. In addition, the target frequency is the maximum safe frequency of the unit under the current ambient temperature. This frequency can be calibrated in advance according to the unit model and the ambient temperature characteristics, so as to ensure that the unit is not overloaded after frequency rising. The target frequency is generally greater than or equal to 80Hz and less than or equal to 120Hz.

[0045] For example, after detecting that the ripple frequency corresponding to the bus voltage is 100Hz for the first time, it can be indicated that the three-phase power system can have the open-phase fault or the three-phase unbalance fault. In order to further determine the specific fault type, the running frequency of the unit of the three-phase power system can be controlled to rise to the maximum safe frequency of the unit under the current ambient temperature.

[0046] In step S130, it needs to be noted that when the unit is overloaded, if it is the three-phase unbalance fault, at this time, a small wave head (a small wave peak of short-time voltage rising / dropping) will appear in the waveform of the ripple frequency of the bus voltage, and the waveform of the ripple frequency of the open-phase fault will not appear the above small wave head. Therefore, on the premise that it has been determined that the three-phase power system can have the open-phase fault or the three-phase unbalance fault, the fault type of the three-phase power system can be more accurately determined based on the bus voltage after frequency rising.

[0047] In this embodiment, no additional hardware sensor or protection module is needed, which can greatly reduce the cost and hardware complexity of the three-phase power system, reduce the fault point, and improve the reliability. In addition, the present disclosure can accurately distinguish the open-phase fault and the three-phase unbalance fault through the "frequency rising verification", avoid the shutdown or protection omission caused by the misjudgment of the existing method, improve the unit operation efficiency, and can significantly improve the power supply reliability and operation safety of the large-power air conditioning equipment.

[0048] In one example embodiment, reference is made to Figure 2 , Figure 5 and Figure 6As shown, a fault detection method for a three-phase power system is provided. In this embodiment, determining the fault type of the three-phase power system based on the bus voltage at a target frequency may include: S210, Monitor the rising edge signal of the bus voltage; S220. If M consecutive rising edge signals are detected, calculate the time difference between the corresponding time of the next rising edge signal and the corresponding time of the current rising edge signal. S230. If the time difference is determined to be within the first time range, then the fault type is determined to be a three-phase imbalance fault. S240. If the time difference is determined to be within the second duration range, it is determined to be a single phase loss waveform characteristic. S250. If it is determined that the phase loss waveform feature is detected N times within the first time period, then the fault type is determined to be a phase loss fault.

[0049] In step S210, the rising edge signal refers to the moment when the voltage waveform jumps from a low level to a high level. It can be implemented by a voltage comparator circuit or the edge-triggered interrupt function of a microcontroller. The purpose is to accurately capture the key change points of the voltage ripple and provide a stable and reproducible reference for subsequent time analysis.

[0050] In step S220, monitoring the M consecutive rising edge signals refers to accumulating the count of consecutive rising edges using a counter. This can be implemented using a digital logic counter or a software counter, with the aim of eliminating transient interference from random noise and ensuring the reliability and anti-interference capability of the signal detection. M can be set according to the actual situation, and its specific value is not limited. For example, M can be a positive integer greater than or equal to 3 and less than or equal to 7.

[0051] The time difference refers to the time interval between adjacent rising edges, which can be measured using a timer or timestamp recording module to reflect the characteristics of the ripple period.

[0052] In some implementations, M can be 5. In this implementation, if five consecutive rising edge signals are detected, the time difference between the corresponding time of the next rising edge signal and the corresponding time of the current rising edge signal can be calculated, that is, the time difference between the corresponding time of the sixth rising edge signal and the corresponding time of the fifth rising edge signal can be calculated.

[0053] In step S230, the first duration range refers to the threshold interval of the time difference, which can be set based on the ripple period characteristics corresponding to the fault type. The purpose is to clearly distinguish this range from the typical time characteristics of a phase loss fault. For example, the first duration range can be 2ms-4ms. That is, if the time difference is determined to be greater than or equal to 2ms and less than or equal to 4ms, the fault type is determined to be a three-phase imbalance fault.

[0054] In addition, considering the complexity of the power grid environment, to avoid the influence of power grid harmonic interference or transient fluctuation on the sampling time, the three-phase unbalanced fault misjudgment is regarded as the open-phase fault, and the current phase difference dynamic compensation and the capacitance voltage decay rate compensation judgment mechanism are introduced. That is, after the fault type is determined based on the bus voltage at the target frequency, the current phase difference dynamic compensation and the capacitance voltage decay rate compensation judgment mechanism also need to be met to finally determine the fault type.

[0055] Wherein, after determining that the time difference is in the first time range, the condition for determining that the fault type is a three-phase unbalanced fault includes: determining that the phase difference change rate of at least two-phase currents of the three-phase current of the three-phase electric system is less than or equal to a first set change rate; and / or, determining that the decay rate of the bus voltage in the period corresponding to the fault frequency is in a first decay rate range.

[0056] Wherein, the phase difference change rate of at least two-phase currents of the three-phase current refers to the change rate of the phase difference between any two phases of the three-phase current with time, which can be realized by sampling the current signal in real time and calculating the phase difference differential, and its purpose is to capture the dynamic characteristics of the current phase to distinguish the fault mode; wherein, the first set change rate 30° / s can be understood as a judgment threshold of the phase difference change rate, which can be realized by software threshold comparison or hardware comparator circuit, and its purpose is to effectively identify the feature that the phase difference changes slowly in the three-phase unbalanced fault, and avoid misjudging the sharp fluctuation of the open-phase fault as the three-phase unbalanced fault; in actual application, the decay rate of the bus voltage in the period corresponding to the fault frequency refers to the decline rate of the bus voltage in the 100Hz period, which can be realized by measuring the time difference and voltage difference between the voltage peaks and calculating the slope, and its purpose is to reflect the fault essence difference by using the voltage decay characteristics; wherein, the first decay rate range 15V / ms-25V / ms can be understood as the allowed interval of the decay rate, which can be realized by range detection logic or digital filtering algorithm, and its purpose is to select the slow decay characteristics specific to the three-phase unbalanced fault and exclude the rapid decay interference of the open-phase fault.

[0057] When the time difference is in the first time range (2-4 ms), the system verifies the phase difference change rate of the three-phase current and the bus voltage decay rate: the three-phase unbalanced fault usually causes the current phase difference to change slowly (change rate ≤ 30° / s) and the bus voltage to decay gently (decay rate is 15-25 V / ms), while the open-phase fault causes the phase difference to fluctuate rapidly (change rate > 30° / s) and the voltage to decay sharply (decay rate > 25 V / ms). Through the joint determination of the double characteristics, the ambiguity of the single time difference index can be eliminated. The use of the "and / or" logic relationship enables the system to still verify independently based on the effective characteristics when part of the sensor signals are abnormal, ensuring the robustness of fault identification and adapting to the dynamic needs of different power grid conditions.

[0058] In some embodiments, when the time difference is 3 ms, the system acquires the three-phase current signals in real time, calculates the phase difference change rate of the a-phase and c-phase currents, and if the change rate is 25° / s and the decay rate of the bus voltage in the 100 Hz cycle is 20 V / ms, the first set change rate and the double verification of the first decay rate range confirm the three-phase unbalanced fault. If only the phase difference change rate meets the condition and the decay rate exceeds the range, a secondary verification mechanism is triggered to exclude interference.

[0059] Through the above scheme, the embodiment can effectively avoid misjudgment of three-phase unbalanced fault and open-phase fault, reduce the risk of equipment operation interruption caused by false shutdown, prevent damage to the capacitor element caused by abnormal fluctuations of the bus voltage, and significantly improve the accuracy of fault detection and the safety of system operation.

[0060] In step S240, the minimum value of the second time range is greater than the maximum value of the first time range. The selection of the range is based on the voltage ripple characteristics specific to the open-phase fault and the system response delay, and a digital filtering algorithm or a hardware comparator can be used to realize boundary determination. The purpose is to form strict mutual exclusion with the time difference range of the three-phase unbalanced fault, avoiding confusion of fault characteristics. The specific range of the second time range can be set according to actual needs, for example, the second time range can be 8-10 ms.

[0061] Among them, the determination of the primary open-phase characteristic refers to triggering a characteristic recording event when the time difference falls within the second time range, which can be realized based on a programmable logic array or a software state machine. The purpose is to accumulate fault characteristics to verify fault persistence.

[0062] For example, the second time range can be 8ms-10ms. If the time difference is greater than or equal to 8ms and less than or equal to 10ms, it is marked as a single-phase failure feature. The second time range (8ms-10ms) forms a clear boundary with the first time range (2ms-4ms) of the three-phase imbalance fault, thereby eliminating the ambiguous area of fault type discrimination.

[0063] In step S250, N is a set value, which can be set according to actual conditions, and the specific value is not limited. The first time length is also a set value, which can be set according to actual conditions, and the specific value is not limited.

[0064] For example, under the condition of a 50Hz power grid, the phase failure waveform period is generally about 10ms, and 3 consecutive phase failure waveform features can be detected within 40ms. Therefore, N can be set to 3, and the first time length can be set to 40ms. That is, the phase failure features are counted within a time window of 40ms, and when the cumulative number reaches 3, the phase failure is confirmed. This dual verification mechanism based on time range exclusion and feature accumulation effectively utilizes the period stability of the voltage ripple under phase failure, while avoiding false triggering caused by transient voltage fluctuations, and realizes accurate identification of fault types.

[0065] In addition, in this step, the condition for determining that the fault type is a phase failure after N times of the phase failure waveform feature appearing within the first time length can also include: determining that the phase difference change rate of any two-phase current of the three-phase current of the three-phase power system is greater than or equal to a second set change rate; and / or, determining that the attenuation rate of the bus voltage within the period corresponding to the fault frequency is within a second attenuation rate range.

[0066] In this embodiment, by further verifying the phase difference change rate of the three-phase current or the attenuation rate of the bus voltage after detecting N times of the phase failure feature within the first time length, accurate determination of the phase failure is realized. Since the phase failure causes the loss of one-phase current, the phase difference of the remaining two-phase current will change sharply, and its change rate is significantly higher than the slow change characteristic of the three-phase imbalance fault. Therefore, when the phase difference change rate of any two-phase current reaches or exceeds 90° / s, it can be confirmed as a phase failure. At the same time, the phase failure causes severe oscillation of the system, and the attenuation rate of the bus voltage is much faster than that of the three-phase imbalance fault. When the attenuation rate is greater than or equal to 25V / ms, it also indicates that there is a phase failure. The use of "and / or" logic design allows the system to confirm the phase failure when any condition is met, which not only improves the flexibility of detection, but also avoids the risk of false judgment of a single parameter, thereby reliably distinguishing the fault types under complex working conditions.

[0067] In some embodiments, a microcontroller is configured in a control unit of a three-phase power system, which acquires three-phase current signals through an isolated current sensor and obtains bus voltage signals through a resistive voltage dividing network. A capture module of the microcontroller is used to monitor the time difference of rising edge signals, and a calculation unit is used to analyze the phase difference change trend of any two phases and the attenuation characteristics of the bus voltage within a 100Hz cycle in real time. When 3 times of open-phase characteristics within 40ms are detected, the control unit further judges whether the phase difference change rate is greater than or equal to 90° / s or the bus voltage attenuation rate is greater than or equal to 25V / ms, and if any condition is met, an open-phase fault determination logic is triggered.

[0068] Through the above technical solution, the embodiment can effectively avoid misjudging three-phase imbalance faults as open-phase faults, reduce unplanned shutdown events caused by misjudgment, and at the same time ensure timely identification and processing of real open-phase faults, thereby improving the safety and stability of the three-phase power system operation and prolonging the service life of the unit.

[0069] In one exemplary embodiment, referring to Figure 3 and Figure 4 a fault detection method for a three-phase power system is provided. In the fault detection method of the embodiment, after the fault type is determined, subsequent control can be performed based on the fault type to better protect the safety of the three-phase power system.

[0070] The fault detection method can include: S310, if the fault type is determined to be a three-phase imbalance fault, the operating frequency of the unit of the three-phase power system is restored to a reference frequency; S320, based on the peak-to-peak value of the bus voltage at the reference frequency and a set threshold, the operating frequency of the unit of the three-phase power system is controlled.

[0071] In step S310, the reference frequency can refer to the standard frequency of the three-phase power system in a normal operating state, which can be implemented by using a power grid standard frequency (such as 50Hz or 60Hz), and the purpose is to provide a stable reference operating point and eliminate the interference introduced by the frequency increase operation in the fault detection process.

[0072] In this step, by immediately restoring the operating frequency to the reference frequency after determining the three-phase imbalance fault, the voltage fluctuation interference caused by the previous frequency increase operation is effectively eliminated, the system returns to the stable operating point, and a reliable reference condition is provided for subsequent voltage monitoring.

[0073] In step S320, the peak-to-peak value of the bus voltage can refer to the maximum amplitude of the bus voltage. The set threshold value can refer to a voltage limit value for judging the capacitor safety state, which is configured to be 80%-90% of the rated voltage of the capacitor, aiming to reserve a safety margin while ensuring normal operation of the system, strictly avoiding the critical risk of approaching the rated voltage, which can be set according to the model and voltage withstand parameter of the bus capacitor.

[0074] Wherein, if the peak-to-peak value is less than or equal to the set threshold value, the unit of the three-phase power system is controlled to maintain the current frequency operation. It should be noted that since the reference frequency represents the stable operation state after fault recovery, the bus voltage measurement is not disturbed by the fault frequency at this time, and can accurately reflect the actual voltage fluctuation level; by directly comparing the peak-to-peak value with the threshold value to perform the frequency maintenance operation, the system omits the redundant judgment link, ensures the running continuity when the voltage fluctuation amplitude is within the safe range, thereby avoiding the accumulation of mechanical stress of equipment and the risk of capacitor overvoltage caused by frequent frequency adjustment.

[0075] Wherein, if the peak-to-peak value is greater than the set threshold value, the operating frequency of the unit of the three-phase power system is reduced at a set frequency reduction gradient until the peak-to-peak value is less than or equal to the set threshold value, or until the operating frequency of the unit of the three-phase power system is reduced to the minimum safe frequency.

[0076] It should be noted that the set frequency reduction gradient refers to the rate of frequency reduction per unit time, which can be determined by a fixed step or an adaptive algorithm, aiming to control the smoothness of frequency adjustment and prevent secondary faults caused by frequency mutation. The set frequency reduction gradient can be greater than or equal to 5 Hz and less than or equal to 25 Hz. The minimum safe frequency can be pre-calibrated to ensure the basic function of the unit. For example, the minimum safe frequency can be greater than or equal to 20 Hz and less than or equal to 30 Hz.

[0077] When the peak-to-peak value of the bus voltage at the reference frequency exceeds the set threshold value, the system triggers the frequency reduction mechanism to gradually reduce the operating frequency of the unit at a preset frequency reduction gradient. This process continuously monitors the change of the peak-to-peak value, and if the peak-to-peak value falls within the set threshold value, the frequency reduction is terminated, and if the operating frequency is reduced to the minimum safe frequency and the peak-to-peak value still does not meet the standard, the standby protection is started. The design of this double termination condition enables the system to dynamically respond to voltage fluctuations: by controlling the frequency adjustment rate through the frequency reduction gradient, it avoids system instability caused by sudden drop and ensures that the overvoltage problem is handled in a timely manner; the peak-to-peak value monitoring serves as a real-time feedback basis to accurately identify voltage state changes; the minimum safe frequency serves as a hard boundary to prevent excessive reduction of frequency from causing operation failure. The coordination of each link forms a closed-loop control, making the frequency adjustment process have both response speed and stability.

[0078] The embodiment can implement a controllable dynamic frequency reduction strategy according to the real-time comparison result of the bus voltage peak-peak value and the set threshold. The strategy effectively avoids the risk of capacitor overvoltage damage caused by the continuous overhigh bus voltage, and prevents the problem of unstable system operation caused by the excessively large or excessively fast frequency adjustment amplitude, thereby significantly improving the safe operation capability of the three-phase electric system in the fault state.

[0079] wherein, after the operating frequency of the unit of the three-phase electric system is reduced to the lowest safe frequency, if the peak-peak value is greater than the set threshold, the unit of the three-phase electric system is controlled to shut down.

[0080] In the embodiment, a peak-peak value monitoring mechanism is introduced after the operating frequency is reduced to the lowest safe frequency, and a shutdown operation is immediately performed when it is detected that the peak-peak value exceeds the set threshold. When the operating frequency of the unit has been adjusted to the lower limit of the system operation, i.e., the lowest safe frequency, if the bus voltage peak-peak value is still greater than the set threshold, it indicates that the frequency reduction measure has failed to effectively suppress the voltage overload, at which time the system automatically triggers a shutdown instruction to completely cut off the power input, thereby avoiding the risk of the capacitor continuously bearing overvoltage. The mechanism ensures that only when the voltage state continues to deteriorate after the frequency reduction protection measure is implemented to the system operation limit, the forced protection is started, which avoids the false shutdown caused by temporary fluctuations, provides sufficient buffer space for fault handling, and realizes precise protection of the capacitor safety, thereby significantly improving the safety and reliability of the system and prolonging the service life of the equipment.

[0081] In addition, in the embodiment, the fault detection method can further include: S410, if it is determined that the fault type is an open-phase fault, it is determined that H times of open-phase faults occur within a second time length, and the unit of the three-phase electric system is controlled to shut down.

[0082] In this step, H refers to a number threshold of times of open-phase faults confirmed within the second time length, which can be implemented by an integer between 1800 and 2000, and the purpose is to ensure the persistence of the fault by setting a higher number threshold, thereby effectively filtering transient fluctuations of the power grid; wherein the second time length refers to a time window for counting the number of faults, which can be set to 90 seconds, and the purpose is to provide a sufficient time span to distinguish between transient abnormalities and real faults.

[0083] It should be noted that, under the condition of a 50Hz power grid, the open-phase waveform period is about 10ms, and 3 times of open-phase waveform characteristics detected continuously within 40ms are considered as an open-phase fault. In an ideal case, 2250 times of open-phase faults can be detected within 90 seconds, and therefore, the trigger condition is set to 1800-2000 times, which can reduce false positives and improve protection reliability.

[0084] In this embodiment, the number of occurrences of the open-phase fault is continuously monitored within a time window of 90 seconds after the fault confirmation process is started upon detection of the open-phase fault; based on the fault detection mechanism of claims 1-5, the system periodically confirms the open-phase feature and accumulates the number of fault confirmations within the time window; only when the number of faults reaches or exceeds 1800, the shutdown operation is triggered; this takes advantage of the characteristics that real open-phase faults will occur stably in continuous operation while transient disturbances will only cause temporary abnormalities, thus forming a double verification mechanism to avoid misjudgment caused by accidental open-phase features, avoid unnecessary shutdown operations triggered by temporary abnormalities, reduce equipment operation interruption, and improve the operation continuity and stability of the three-phase power system.

[0085] In one exemplary embodiment, referring to Figures 1 to 6 , a fault detection method for a three-phase power system is provided. In this embodiment, when the input three-phase power supply is normal in the three-phase power system, the ripple frequency of the bus voltage is generally 300 Hz. When the input power supply is open-phase or three-phase unbalanced and the unit is in low-frequency operation, three-phase unbalance and open-phase may exhibit the same characteristics, at which time the ripple frequency of the bus voltage is generally 100 Hz and presents a monotonic decreasing state, as shown in Figure 5 . When the unit is in heavy load operation, if it is three-phase unbalanced, it will cause a small wave head (short-time voltage lifting / descending wave peak) in the waveform of the bus voltage ripple frequency, as shown in Figure 6 . It should be noted that, Figure 5 and Figure 6 , ia represents the waveform of the current of phase a in the three-phase power, ib represents the waveform of the current of phase b in the three-phase power, and ic represents the waveform of the current of phase c in the three-phase power.

[0086] In order to accurately distinguish between the above open-phase fault and three-phase unbalanced fault, avoid misjudgment of protection shutdown or damage to the bus capacitor due to three-phase unbalanced not being processed in time, this embodiment proposes a fault detection method for detecting and distinguishing between open-phase fault and three-phase unbalanced fault.

[0087] In this embodiment, the bus voltage of the unit of the three-phase power system can be collected in real time, and the ripple frequency of the bus voltage is analyzed. If the ripple frequency is not 100 Hz, it is determined that the power grid is normal, that is, there is no three-phase imbalance fault and open-phase fault in the three-phase power system, and the unit can maintain the current frequency operation. If the ripple frequency of the bus voltage is detected for the first time as 100 Hz, it indicates that there is a risk of open-phase fault or three-phase imbalance fault, and the unit can be controlled to increase the frequency to the maximum operating frequency (denoted as target frequency) that can be maintained at the current ambient temperature (the frequency needs to be pre-calibrated according to the unit model and ambient temperature characteristics to ensure that the unit does not overload temporarily after frequency increase, and generally can be 80 Hz-120 Hz). After the operating frequency of the unit is increased to the target frequency, the ripple frequency and waveform of the bus voltage are detected again. If the ripple frequency remains 100 Hz, it indicates that there is no waveform abnormality, and it is determined that it is an open-phase fault (because the bus capacitor cannot be charged through the open-phase branch in the open-phase fault, the ripple frequency is stable at 100 Hz). After detecting the open-phase waveform for multiple times, the unit is immediately controlled to stop to avoid damage caused by overloading of the unit due to the open-phase. If the waveform of the ripple frequency of the bus voltage appears a small wave head, it is determined to be a three-phase imbalance. The frequency of the unit is restored to the reference frequency before the frequency increase, and the peak-to-peak value (i.e., the maximum amplitude) of the bus voltage after the restored frequency is detected and compared with a pre-set capacitor safety peak-to-peak threshold value (i.e., a set threshold value, which is set according to the model and voltage resistance parameters of the bus capacitor, and generally is set to 80%-90% of the rated voltage of the capacitor, for example, the threshold value of a 450 V capacitor can be set to 360 V-405 V).

[0088] If the peak-to-peak value is less than or equal to the set threshold value, it is determined that the bus capacitor can withstand the current load, and the unit can be controlled to maintain the current frequency for continuous operation.

[0089] If the peak-to-peak value is greater than the set threshold value, the unit is controlled to gradually decrease the frequency by a pre-set frequency decrease amplitude (i.e., a set frequency decrease gradient, which is in the range of 5 Hz-25 Hz, for example, 10 Hz can be used, and a moderate frequency decrease amplitude is selected to protect the bus capacitor and to meet the unit performance as much as possible), and the peak-to-peak value is detected again after the frequency decrease until the peak-to-peak value is less than or equal to the set threshold value. If the peak-to-peak value of the bus voltage is still greater than the set threshold value after the unit is decreased to the lowest safe frequency (pre-calibrated to ensure the basic function of the unit, generally 20 Hz-30 Hz, for example, 30 Hz, which can reduce the risk of equipment damage), it is determined that the bus capacitor cannot meet the current power grid condition (the capacitor performance is degraded or the three-phase imbalance degree exceeds the limit), and the unit is immediately controlled to stop to avoid damage caused by capacitor breakdown.

[0090] It should be noted that when the unit has an open-phase fault or a three-phase imbalance fault, the ripple amplitude of the bus voltage significantly increases, and the frequency decreases. The three-phase power system can realize real-time judgment of the fault state by collecting the bus voltage in real time and extracting the waveform characteristics thereof.

[0091] Wherein, when the fault type is judged after the machine set is controlled to increase to the target frequency, the system can continuously monitor the rising edge signal of the bus voltage, if 5 rising edges are continuously detected, it is determined that the waveform of the ripple frequency is in the rising state at this time, the time point of the rising edge is recorded as the reference time, the time of the next rising edge is detected, and the time difference t1 between the two rising edges is calculated.

[0092] Wherein, when t1 is in the range of 2ms-4ms (i.e. 2ms≤t1≤4ms), it indicates that the waveform of the bus voltage has a small wave head (because the lower phase of the three-phase imbalance can intermittently charge the bus capacitor, forming a small wave head), indicating that the three-phase imbalance fault occurs in the input power supply.

[0093] When t1 is in the range of 8ms-10ms (corresponding to the standard period of 50Hz / 60Hz power grid frequency), it is determined to be a phase loss waveform feature, the system records the number of times N of the phase loss waveform feature, and further counts whether 3 phase loss waveform features occur within 40ms (under the condition of 50Hz, the phase loss waveform period is about 10ms, and 3 consecutive phase loss waveform features can be detected within 40ms). If the condition is met, it is determined to be a phase loss fault (the cumulative number of phase loss faults is S). If 1800-2000 phase loss faults are accumulated within 90s, the phase loss protection mechanism is triggered, and the machine set is controlled to stop. For example, the power supply can be cut off or the emergency shutdown program can be started to prevent the motor from overheating or damage due to phase loss operation.

[0094] It should be noted that under the condition of 50Hz power grid, the phase loss waveform period is about 10ms, and 3 consecutive phase loss waveform features within 40ms are considered as a phase loss fault. Ideally, 2250 phase loss faults can be detected within 90 seconds, so the trigger condition is set to 1800-2000 times, which can reduce false positives and improve protection reliability.

[0095] In addition, in this embodiment, considering the complex power grid environment, to avoid the influence of power grid harmonic interference or instantaneous fluctuation on the sampling time, current phase difference dynamic compensation and capacitor voltage decay rate compensation judgment mechanism are introduced to avoid misjudgment of three-phase imbalance fault as phase loss fault. That is, after the fault type is determined based on the bus voltage under the target frequency, the current phase difference dynamic compensation and capacitor voltage decay rate compensation judgment mechanism must be met to finally determine the fault type.

[0096] Wherein, the current phase difference dynamic compensation mechanism is: The system calculates the phase difference change rate (Δθ / Δt) of the three-phase current in real time: (1) If the phase difference change rate Δθ of two-phase current is greater than or equal to 90° / s, it is determined that the fault type is a phase loss fault; (2) If the phase difference change rate Δθ of any two-phase current is less than or equal to 30° / s, it can be determined that it is a three-phase unbalanced fault.

[0097] In the capacitor voltage decay rate compensation mechanism: The decay slope (|dV / dt|) of the bus capacitor voltage in a 100Hz cycle is calculated: (1) If the decay slope |dV / dt| is greater than or equal to 25V / ms, it is determined to be an open-phase fault (only two-phase continuous current, steep slope). (2) If the decay slope |dV / dt| is greater than or equal to 15V / ms and less than or equal to 25V / ms, it can be determined that it is a three-phase unbalanced fault (three-phase intermittent current, gentle slope).

[0098] That is, for a three-phase unbalanced fault, in this embodiment, when t1 is in the 2ms-4ms time range, if it is also determined that the phase difference change rate Δθ of any two-phase current is less than or equal to 30° / s, it can be determined that the fault type is a three-phase unbalanced fault. When t1 is in the 2ms-4ms time range, if it is also determined that the decay slope |dV / dt| is greater than or equal to 15V / ms and less than or equal to 25V / ms, it can be determined that the fault type is a three-phase unbalanced fault. When t1 is in the 2ms-4ms time range, if it is also determined that the phase difference change rate Δθ of any two-phase current is less than or equal to 30° / s, and it is also determined that the decay slope |dV / dt| is greater than or equal to 15V / ms and less than or equal to 25V / ms, it can be determined that the fault type is a three-phase unbalanced fault. For the determination of an open-phase fault, reference can be made to the three-phase unbalanced fault described above, which will not be described here.

[0099] In this embodiment, no additional hardware sensors or protection modules are required, greatly reducing system cost and hardware complexity, while reducing fault points and improving reliability. Moreover, this embodiment accurately distinguishes between open-phase and three-phase imbalance through "frequency increase verification", avoiding downtime or missed protection caused by misjudgment of existing methods, and improving unit operation efficiency. In addition, this embodiment designs a peak-to-peak value grading protection for three-phase imbalance, avoids excessive voltage impact on the capacitor through frequency reduction control, and prolongs the service life of the capacitor. Furthermore, capacitor voltage impact protection and operation efficiency optimization are realized for three-phase imbalance scenarios, prolonging equipment life and reducing unnecessary downtime.

[0100] That is, the embodiment provides a detection and processing method capable of accurately distinguishing between input power open-phase and three-phase imbalance, effectively solving the misjudgment problem of traditional methods, and significantly improving the power supply reliability and operation safety of large-power air conditioning equipment.

[0101] In one exemplary embodiment, reference is made to Figure 7As shown, a fault detection device is provided, applied to a three-phase power system. This device is used to implement the fault detection method described above. For example, the device may include: Monitoring module 10 is used to monitor the bus voltage of the unit in a three-phase power system; Control module 20 is used to control the operating frequency of the three-phase power system unit to be increased to the target frequency after the ripple frequency corresponding to the bus voltage is detected as the fault frequency for the first time. The determination module 30 is used to determine the fault type of the three-phase power system based on the bus voltage at the target frequency.

[0102] In one exemplary embodiment, reference Figure 7 As shown, a fault detection device is provided, applied to a three-phase power system, for implementing the aforementioned fault detection method. In this embodiment, The monitoring module 10 can be used to monitor the rising edge signal of the bus voltage; The determination module 30 can be used to calculate the time difference between the corresponding time of the next rising edge signal and the corresponding time of the current rising edge signal if M consecutive rising edge signals are detected; where M is a positive integer greater than or equal to 3 and less than or equal to 7. The determination module 30 can also be used to determine the fault type as a three-phase imbalance fault if the time difference is determined to be within a first duration range.

[0103] In one exemplary embodiment, reference Figure 7 As shown, a fault detection device is provided, applied to a three-phase power system, which is used to implement the fault detection method described above. In this embodiment, the determining module 30 can be used for: If the time difference is determined to be within the second duration range, it is determined to be a single phase loss waveform characteristic; wherein, the minimum value of the second duration range is greater than the maximum value of the first duration range; If the phase loss waveform feature is detected N times within the first time period, then the fault type is determined to be a phase loss fault.

[0104] In one exemplary embodiment, reference Figure 7 As shown, a fault detection device is provided, applied to a three-phase power system, for implementing the aforementioned fault detection method. In this embodiment, the control module 20 can be used to: If the fault type is determined to be a three-phase imbalance fault, the operating frequency of the three-phase power system unit shall be restored to the reference frequency. The operating frequency of the three-phase power system is controlled based on the peak-to-peak value of the bus voltage at the reference frequency and a set threshold.

[0105] In one exemplary embodiment, reference Figure 7 As shown, a fault detection device is provided, applied to a three-phase power system, for implementing the aforementioned fault detection method. In this embodiment, the control module 20 can be used to: If the peak value is less than or equal to the set threshold, the generator set of the three-phase power system is controlled to maintain the current frequency operation.

[0106] In one exemplary embodiment, reference Figure 7 As shown, a fault detection device is provided, applied to a three-phase power system, for implementing the aforementioned fault detection method. In this embodiment, the control module 20 can be used to: If the peak-to-peak value is greater than the set threshold, the operating frequency of the three-phase power system unit is reduced by a set frequency reduction gradient until the peak-to-peak value is less than or equal to the set threshold, or until the operating frequency of the three-phase power system unit is reduced to the minimum safe frequency.

[0107] In one exemplary embodiment, reference Figure 7 As shown, a fault detection device is provided, applied to a three-phase power system, for implementing the aforementioned fault detection method. In this embodiment, the control module 20 can be used to: After the operating frequency of the three-phase power system unit is reduced to the minimum safe frequency, if the peak-to-peak value is greater than the set threshold, the three-phase power system unit is controlled to shut down.

[0108] In one exemplary embodiment, reference Figure 7 As shown, a fault detection device is provided, applied to a three-phase power system, for implementing the aforementioned fault detection method. In this embodiment, the control module 20 can be used to: If the fault type is determined to be a phase loss fault, then after H occurrences of the fault within the second time period, the unit of the three-phase power system is controlled to shut down; where H is a positive integer greater than or equal to 1800 and less than or equal to 2000.

[0109] In one exemplary embodiment, a three-phase electrical system is provided for implementing the fault detection method described above.

[0110] The bus voltage of the unit of the three-phase power system can be monitored. After detecting for the first time that the bus voltage corresponds to a fault frequency (for example, 100 Hz), the operating frequency of the unit of the three-phase power system can be controlled to increase to a target frequency (for example, the maximum allowable operating frequency of the unit of the three-phase power system at the current ambient temperature), and the fault type of the three-phase power system can be determined according to the bus voltage after the increase (that is, the bus voltage at the target frequency). The three-phase power system does not require additional hardware sensors or protection modules, which can greatly reduce the cost and hardware complexity of the three-phase power system, reduce the fault points, and improve the reliability. In addition, the three-phase power system can accurately distinguish between open-phase faults and three-phase unbalanced faults through "frequency increase verification", avoid shutdown or protection failure caused by misjudgment of the existing method, improve the operation efficiency of the unit, and significantly improve the power supply reliability and operation safety of high-power air conditioning equipment.

[0111] As shown in Figure 8 The electronic device provided by the embodiments of the present application can be applied to a three-phase power system and is used for fault detection of the three-phase power system. When the three-phase power system is used to supply power to an air conditioning device, the electronic device can be the air conditioning device or a computer device electrically connected to the air conditioning device, and the present application is not limited in this regard. The electronic device can include a processor 111, a communication interface 112, a memory 113, and a communication bus 114, wherein the processor 111, the communication interface 112, and the memory 113 can communicate with each other through the communication bus 114, The memory 113 is used to store a computer program. In an embodiment of the present application, the processor 111 is used to execute the program stored in the memory 113, and the fault detection method provided by any one of the preceding method embodiments is implemented. The embodiments of the present application also provide a computer readable storage medium having a computer program stored thereon. The computer program is executed by a processor to implement the steps of the fault detection method provided by any one of the preceding method embodiments.

[0112] Those skilled in the art should further appreciate that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be realized in electronic hardware, computer software, or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of the examples have been described in the above description in a general manner. Whether the functions are performed 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 the present application.

[0113] It should be noted that the terms "one embodiment", "an embodiment", "certain embodiments", "some embodiments", "one example", "an example", "certain examples", "some examples" and the like, mean at least one embodiment. The phrases "in one embodiment", "in an embodiment", "in certain embodiments", "in some embodiments", "in one example", "in an example", "in certain examples", "in some examples" and the like, do not necessarily refer to the same embodiment, although they can. Furthermore, the terms "a" or "an", as used herein, mean "one or more". The terms "plurality" or "a plurality" mean "two or more". The terms "another" and "an additional" mean "at least a second" or "at least a third". The term "additional" means "at least one more". The term "substantially" and its derivatives mean "largely but not necessarily wholly that which is specified, having tolerances that can be expected by persons of ordinary skill in the art, and that which is modified in operation according to the intended function to which the modifier "substantially" refers. The term "primarily" means "largely but not necessarily wholly that which is specified as the primary or main constituent or characteristic of something or someone by persons of ordinary skill in the relevant art(s). The term "comprising", used in the description and / or claims, means "including, but not limited to" and is not intended to (and does not) exclude other moieties, additives, components, integers or steps. Thus, the term "comprising" as used herein is synonymous with the term "including". Moreover, the term "comprising" is not intended to exclude "consisting" or "consisting essentially of". In some embodiments, the term "consisting essentially of" means that a process, method, article, or apparatus can include additional elements so long as such additional elements do not materially alter the basic and novel characteristics of the claimed process, method, article, or apparatus. In some embodiments, the term "consisting of" means an inclusion without additional elements, additives, components, integers or steps.

[0114] It should be noted that, in the present document, the terms "first", "second", "third", etc. and the like are used merely to distinguish one entity or action from another, without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0115] The above embodiments are only preferred examples of the present application, and the protection scope of the present application is not limited thereto. Any equivalent replacement or transformation of the present application made by those skilled in the art based on the present application is within the protection scope of the present application.

Claims

1. A fault detection method for a three-phase electrical system, characterized in that, The fault detection method includes: Monitor the bus voltage of the generator unit in a three-phase power system; After the first detection that the ripple frequency corresponding to the bus voltage is the fault frequency, the operating frequency of the three-phase power system unit is increased to the target frequency. The fault type of the three-phase power system is determined based on the bus voltage at the target frequency.

2. The fault detection method according to claim 1, characterized in that, Determining the fault type of the three-phase power system based on the bus voltage at the target frequency includes: Monitor the rising edge signal of the bus voltage; If M consecutive rising edge signals are detected, the time difference between the corresponding time of the next rising edge signal and the corresponding time of the current rising edge signal is calculated; where M is a positive integer greater than or equal to 3 and less than or equal to 7. If the time difference is determined to be within the first time range, then the fault type is determined to be a three-phase imbalance fault.

3. The fault detection method according to claim 2, characterized in that, After determining that the time difference is within the first duration range, the conditions for determining that the fault type is a three-phase imbalance fault include: It is determined that the rate of change of the phase difference between at least two phases of the three-phase current in the three-phase electrical system is less than or equal to a first predetermined rate of change; and / or, The attenuation rate of the bus voltage within the period corresponding to the fault frequency is determined to be within the first attenuation rate range.

4. The fault detection method according to claim 2, characterized in that, The fault detection method includes: If the time difference is determined to be within the second duration range, it is determined to be a single phase loss waveform characteristic; wherein, the minimum value of the second duration range is greater than the maximum value of the first duration range; If the phase loss waveform feature is detected N times within the first time period, then the fault type is determined to be a phase loss fault.

5. The fault detection method according to claim 4, characterized in that, After determining that the phase loss waveform feature occurs N times within a first time period, the conditions for determining the fault type as a phase loss fault include: It is determined that the rate of change of the phase difference between any two phases of the three-phase current in the three-phase electrical system is greater than or equal to a second preset rate of change; and / or, The attenuation rate of the bus voltage within the period corresponding to the fault frequency is determined to be within the second attenuation rate range.

6. The fault detection method according to any one of claims 1-5, characterized in that, The fault detection method includes: If the fault type is determined to be a three-phase imbalance fault, the operating frequency of the three-phase power system unit shall be restored to the reference frequency. The operating frequency of the three-phase power system is controlled based on the peak-to-peak value of the bus voltage at the reference frequency and a set threshold.

7. The fault detection method according to claim 6, characterized in that, The method of controlling the operating frequency of the three-phase power system units based on the peak-to-peak value of the bus voltage at the reference frequency and a set threshold includes: If the peak value is less than or equal to the set threshold, the generator set of the three-phase power system is controlled to maintain the current frequency operation.

8. The fault detection method according to claim 6, characterized in that, The method of controlling the operating frequency of the three-phase power system units based on the peak-to-peak value of the bus voltage at the reference frequency and a set threshold includes: If the peak-to-peak value is greater than the set threshold, the operating frequency of the three-phase power system unit is reduced by a set frequency reduction gradient until the peak-to-peak value is less than or equal to the set threshold, or until the operating frequency of the three-phase power system unit is reduced to the minimum safe frequency.

9. The fault detection method according to claim 8, characterized in that, The method of controlling the operating frequency of the three-phase power system units based on the peak-to-peak value of the bus voltage at the reference frequency and a set threshold includes: After the operating frequency of the three-phase power system unit is reduced to the minimum safe frequency, if the peak-to-peak value is greater than the set threshold, the three-phase power system unit is controlled to shut down.

10. The fault detection method according to any one of claims 1-5, characterized in that, The fault detection method includes: If the fault type is determined to be a phase loss fault, then after H phase loss faults occur within the second time period, the unit of the three-phase power system is controlled to shut down; where H is a positive integer greater than or equal to 1800 and less than or equal to 2000.

11. The fault detection method according to any one of claims 1-5, characterized in that, The target frequency is the maximum permissible operating frequency of the three-phase power system unit under the current ambient temperature.

12. A fault detection device, characterized in that, The fault detection device is applied to a three-phase power system, and the fault detection device includes: The monitoring module is used to monitor the bus voltage of the unit in a three-phase power system; The control module is used to control the operating frequency of the three-phase power system units to be increased to the target frequency after the ripple frequency corresponding to the bus voltage is detected as the fault frequency for the first time. The determination module is used to determine the fault type of the three-phase power system based on the bus voltage at the target frequency.

13. A three-phase electrical system, characterized in that, The three-phase electrical system is used to implement the fault detection method as described in any one of claims 1-11.

14. An electronic device, characterized in that, The electronic device includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; the memory is used to store computer programs; and the processor is used to implement the fault detection method according to any one of claims 1-11 when executing the computer program.

15. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the fault detection method according to any one of claims 1-11.

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