Fault detection method, device, equipment and medium for uncontrolled rectifier bridge port side

Abstract

The present application discloses a fault detection method, apparatus, device, and medium for the port side of an uncontrolled rectifier bridge. The method includes: obtaining a line voltage measurement signal of the uncontrolled rectifier bridge to construct a six-pulse rectified voltage on its DC output side in a disconnected state; obtaining an estimated bus voltage on the output side of the uncontrolled rectifier bridge based on the voltage; extracting a first pulsating amplitude and a second pulsating amplitude of the estimated bus voltage and the measured bus voltage at 300 Hz, respectively, and extracting a third pulsating amplitude of the six-pulse rectified voltage at 100 Hz; determining whether the bus capacitor on the output side of the uncontrolled rectifier bridge is aging based on the first and second pulsating amplitudes; obtaining a DC component of the six-pulse rectified voltage, and determining whether the grid voltage on the input side of the uncontrolled rectifier bridge is unbalanced based on the DC component and the third pulsating amplitude. This method ensures the reliability of the grid voltage and bus capacitor fault detection results without increasing hardware detection costs.

Description

Technical Field

[0001] The present invention relates to the technical field of frequency converters, and in particular to a fault detection method, device, equipment and medium on the port side of an uncontrolled rectifier bridge. Background Art

[0002] In the field of industrial three-phase inverter drives, the uncontrolled bridge rectifier is the standard rectification solution. After rectifying the grid voltage, the uncontrolled bridge rectifier filters the DC voltage through the bus capacitors to provide the inverter. During uncontrolled bridge rectifier operation, severe grid voltage imbalance or aging of the DC bus capacitors can degrade the inverter's output response, seriously impacting its safe and stable operation. Therefore, in practical applications, real-time detection and handling of these two types of faults are necessary.

[0003] In the prior art, for the imbalance fault of the grid voltage, a common hardware detection method is to determine whether the grid voltage is unbalanced by comparing the effective value of the three-phase line voltage through a hardware comparator. However, this method not only increases the detection cost, but also makes the fault threshold difficult to adjust. Alternatively, the effective value of the three-phase line voltage is calculated by software to determine whether the grid voltage is unbalanced. However, this method cannot distinguish other loads (such as industrial frequency fans) connected in parallel on the input side of the uncontrolled rectifier bridge, which will lead to misjudgment of the detection result. For the aging fault of the bus capacitor, a common hardware detection method is to determine the aging fault of the bus capacitor by detecting the ripple current of the bus. However, this method requires an additional current sensor, which increases the detection cost of the bus capacitor. Alternatively, the bus voltage and current signals are estimated online by software to determine whether the bus capacitor has an aging fault. However, this method not only requires a complex online parameter estimation algorithm, but is also easily affected by the current measurement value.

[0004] Therefore, how to realize fault detection of grid voltage and bus capacitance without increasing hardware detection costs and ensure the reliability of fault detection results is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention aims to provide a method, device, equipment, and medium for detecting faults on the port side of an uncontrolled rectifier bridge, thereby ensuring the reliability of grid voltage and bus capacitance fault detection results without increasing hardware detection costs. The specific solution is as follows:

[0006] A method for detecting a fault on an uncontrolled rectifier bridge port side, comprising:

[0007] Acquire a line voltage measurement signal of an uncontrolled rectifier bridge, and construct a six-pulse rectified voltage of a DC output side of the uncontrolled rectifier bridge in an open circuit condition according to the line voltage measurement signal;

[0008] Obtaining an estimated bus voltage on the DC output side of the uncontrolled rectifier bridge according to the six-pulse rectified voltage;

[0009] extracting the pulsation amplitudes of the estimated bus voltage and the measured bus voltage at 300 Hz respectively to obtain a first pulsation amplitude and a second pulsation amplitude, and extracting the pulsation amplitude of the six-pulse rectified voltage at 100 Hz to obtain a third pulsation amplitude;

[0010] determining whether the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged according to the first pulsating amplitude and the second pulsating amplitude;

[0011] A DC component of the six-pulse rectified voltage is obtained, and it is determined whether an unbalanced fault occurs in the grid voltage at the input side of the uncontrolled rectifier bridge according to the DC component and the third pulsation amplitude.

[0012] Preferably, the process of obtaining the line voltage measurement signal of the uncontrolled rectifier bridge and constructing the six-pulse rectified voltage of the DC output side of the uncontrolled rectifier bridge in the circuit-breaking state according to the line voltage measurement signal includes:

[0013] Obtain the line voltage measurement signal u of the uncontrolled rectifier bridge RS 、u ST and u TR , and according to the first target model, the line voltage measurement signal u RS 、u ST and u TR Constructing the six-pulse rectified voltage at the DC output side of the uncontrolled rectifier bridge in a circuit-breaking condition;

[0014] The expression of the first target model is:

[0015] u rect =max(|u RS |,|u ST |,|u TR |);

[0016] Where u rect is the six-pulse rectified voltage, u RS is the voltage between the R phase and the S phase on the uncontrolled rectifier bridge, u ST is the voltage between the S phase and the T phase on the uncontrolled rectifier bridge, u TR is the voltage value between the T phase and the R phase on the uncontrolled rectifier bridge.

[0017] Preferably, the process of obtaining the estimated bus voltage on the DC output side of the uncontrolled rectifier bridge according to the six-pulse rectified voltage includes:

[0018] Obtaining the estimated bus voltage at the DC output side of the uncontrolled rectifier bridge according to the second target model and the six-pulse rectified voltage;

[0019] The expression of the second target model is:

[0020]

[0021] Where, is the estimated bus voltage at time t, u rect is the six-pulse rectified voltage, R dc and C dc are respectively the equivalent resistance and equivalent capacitance of the DC output side of the uncontrolled rectifier bridge.

[0022] Preferably, the process of respectively extracting the pulsation amplitudes of the estimated bus voltage and the measured bus voltage at 300 Hz to obtain the first pulsation amplitude and the second pulsation amplitude includes:

[0023] extracting a harmonic signal of the estimated bus voltage at 300 Hz using a second-order Butterworth filter to obtain a first harmonic signal, and performing an absolute value operation and a low-pass filter on the first harmonic signal to obtain the first pulsation amplitude;

[0024] The harmonic signal of the measured bus voltage at 300 Hz is extracted using the second-order Butterworth filter to obtain a second harmonic signal, and the second harmonic signal is subjected to absolute value operation and low-pass filtering to obtain the second pulsation amplitude.

[0025] Preferably, the process of determining whether the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged according to the first pulsating amplitude and the second pulsating amplitude includes:

[0026] If the first pulsating amplitude and the second pulsating amplitude meet a preset judgment condition, it is determined that the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged.

[0027] Preferably, the process of determining whether an unbalanced fault occurs in the grid voltage on the input side of the uncontrolled rectifier bridge according to the DC component and the third pulsation amplitude includes:

[0028] performing per-unit processing on the third pulsation amplitude with the DC component as a reference value to obtain a target value;

[0029] If the target value is greater than a preset threshold value, and the duration for which the target value is greater than the preset threshold value is greater than a preset duration, it is determined that an unbalanced fault occurs in the grid voltage on the input side of the uncontrolled rectifier bridge.

[0030] Correspondingly, the present invention also discloses a fault detection device on the port side of an uncontrolled rectifier bridge, comprising:

[0031] a voltage construction module, configured to obtain a line voltage measurement signal of an uncontrolled rectifier bridge and construct a six-pulse rectified voltage of a DC output side of the uncontrolled rectifier bridge in an open circuit condition according to the line voltage measurement signal;

[0032] a voltage estimation module, configured to obtain an estimated bus voltage on the DC output side of the uncontrolled rectifier bridge according to the six-pulse rectified voltage;

[0033] an amplitude extraction module, configured to extract the pulsation amplitudes of the estimated bus voltage and the measured bus voltage at 300 Hz, respectively, to obtain a first pulsation amplitude and a second pulsation amplitude, and to extract the pulsation amplitude of the six-pulse rectified voltage at 100 Hz, to obtain a third pulsation amplitude;

[0034] a first judgment module, configured to determine whether the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged according to the first pulsation amplitude and the second pulsation amplitude;

[0035] The second judgment module is used to obtain the DC component of the six-pulse rectified voltage, and determine whether an unbalanced fault occurs in the grid voltage on the input side of the uncontrolled rectifier bridge according to the DC component and the third pulsation amplitude.

[0036] Correspondingly, the present invention also discloses a fault detection device on the port side of an uncontrolled rectifier bridge, comprising:

[0037] Memory for storing computer programs;

[0038] The processor is configured to implement the steps of the aforementioned method for detecting a fault on the port side of an uncontrolled rectifier bridge when executing the computer program.

[0039] Correspondingly, the present invention also discloses a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the fault detection method on the port side of an uncontrolled rectifier bridge as disclosed above are implemented.

[0040] As can be seen, in the present invention, to detect faults in the grid voltage and bus capacitance at the port side of the uncontrolled rectifier bridge, the first step is to obtain a line voltage measurement signal of the uncontrolled rectifier bridge, and construct a six-pulse rectified voltage at the DC output side of the uncontrolled rectifier bridge in a disconnected state based on the line voltage measurement signal. Then, an estimated bus voltage at the DC output side of the uncontrolled rectifier bridge is obtained based on the six-pulse rectified voltage. The pulsation amplitudes of the estimated bus voltage and the measured bus voltage at 300 Hz are respectively extracted to obtain a first pulsation amplitude and a second pulsation amplitude. Furthermore, the pulsation amplitude of the six-pulse rectified voltage at 100 Hz is extracted to obtain a third pulsation amplitude. Subsequently, whether the bus capacitance at the DC output side of the uncontrolled rectifier bridge has aged is determined based on the first and second pulsation amplitudes. Finally, the DC component of the six-pulse rectified voltage is obtained, and whether an unbalanced grid voltage at the input side of the uncontrolled rectifier bridge has occurred is determined based on the DC component and the third pulsation amplitude. Compared to existing technologies, this method does not require additional hardware detection circuitry. It only requires simple signal measurement and computational transformations to determine whether the grid voltage and bus capacitance on the uncontrolled rectifier bridge port side are faulty, without being affected by other factors. This ensures the reliability of grid voltage and bus capacitance fault detection results without increasing hardware detection costs. Accordingly, the present invention provides a fault detection device, equipment, and medium for uncontrolled rectifier bridge ports, which also have the aforementioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0042] Figure 1 A flow chart of a method for detecting a fault on the port side of an uncontrolled rectifier bridge provided by an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of an uncontrolled rectifier bridge;

[0044] Figure 3 Schematic diagram for extracting the pulsation amplitude in the estimated bus voltage and the measured bus voltage;

[0045] Figure 4 A structural diagram of a fault detection device on the port side of an uncontrolled rectifier bridge provided by an embodiment of the present invention;

[0046] Figure 5 This is a structural diagram of a fault detection device on the port side of an uncontrolled rectifier bridge provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] See Figure 1 , Figure 1 A flow chart of a fault detection method for an uncontrolled rectifier bridge port side provided by an embodiment of the present invention, the method comprising:

[0049] Step S11: obtaining a line voltage measurement signal of the uncontrolled rectifier bridge, and constructing a six-pulse rectified voltage of the DC output side of the uncontrolled rectifier bridge in a circuit-breaking state according to the line voltage measurement signal;

[0050] Step S12: obtaining an estimated bus voltage on the DC output side of the uncontrolled rectifier bridge according to the six-pulse rectified voltage;

[0051] Step S13: extracting the pulsation amplitudes of the estimated bus voltage and the measured bus voltage at 300 Hz respectively to obtain a first pulsation amplitude and a second pulsation amplitude, and extracting the pulsation amplitude of the six-pulse rectified voltage at 100 Hz to obtain a third pulsation amplitude;

[0052] Step S14: determining whether the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged according to the first pulsation amplitude and the second pulsation amplitude;

[0053] Step S15: obtaining the DC component of the six-pulse rectified voltage, and determining whether an unbalanced fault occurs in the grid voltage at the input side of the uncontrolled rectifier bridge according to the DC component and the third pulsation amplitude.

[0054] In this embodiment, a fault detection method for the uncontrolled rectifier bridge port side is provided. This method is used to detect the grid voltage and bus capacitance on the uncontrolled rectifier bridge port side. This not only ensures the reliability of the grid voltage and bus capacitance fault detection results, but also does not increase the hardware detection cost.

[0055] This method first obtains a line voltage measurement signal from the uncontrolled rectifier bridge. Based on this signal, a six-pulse rectified voltage is constructed for the uncontrolled rectifier bridge's DC output in a disconnected state. Once the six-pulse rectified voltage is constructed, an estimated bus voltage can be derived from the six-pulse rectified voltage, as the six-pulse rectified voltage and the bus voltage on the uncontrolled rectifier bridge's DC output are related in a circuit model.

[0056] It's understandable that when the grid voltage on the input side of the uncontrolled rectifier bridge operates normally, the vector sum of the three-phase voltages on the input side of the uncontrolled rectifier bridge is zero. At this point, only a 300Hz ripple amplitude will exist in the six-pulse rectified voltage and bus voltage. Furthermore, if the bus capacitor on the DC output side of the uncontrolled rectifier bridge has not aged, the ripple amplitudes of the estimated and measured bus voltages at 300Hz will maintain a certain proportional relationship. Therefore, based on the ripple amplitudes of the estimated and measured bus voltages at 300Hz, it is possible to determine whether the bus capacitor on the DC output side of the uncontrolled rectifier bridge has aged.

[0057] Specifically, after obtaining the estimated bus voltage and the measured bus voltage, the pulsation amplitudes of the estimated bus voltage and the measured bus voltage at 300 Hz are extracted respectively to obtain the first pulsation amplitude and the second pulsation amplitude. Then, based on the first pulsation amplitude and the second pulsation amplitude, it is determined whether the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged.

[0058] If the grid voltage on the input side of the uncontrolled rectifier bridge experiences an unbalanced fault, the vector sum of the three-phase voltages on the input side of the uncontrolled rectifier bridge will no longer be zero. Consequently, in addition to the 300Hz pulsation amplitude corresponding to the six-pulse rectified voltage, the bus voltage will also experience a 100Hz pulsation amplitude caused by the unbalanced grid voltage. Therefore, in practical applications, to detect whether the grid voltage on the input side of the uncontrolled rectifier bridge has an unbalanced fault, it is necessary to extract the 100Hz pulsation amplitude of the six-pulse rectified voltage. In other words, it is necessary to extract the third 100Hz pulsation amplitude of the six-pulse rectified voltage.

[0059] After obtaining the third pulsation amplitude of the six-pulse rectified voltage at 100 Hz, by comparing the third pulsation amplitude of the six-pulse rectified voltage at 100 Hz with the DC component of the six-pulse rectified voltage, it can be determined whether an unbalanced fault occurs in the grid voltage on the input side of the uncontrolled rectifier bridge.

[0060] It can be imagined that since this method does not require additional hardware detection circuits, it only requires some simple measurement signals and calculation transformations to determine whether the grid voltage and bus capacitance on the uncontrolled rectifier bridge port side are faulty, and will not be interfered by other factors. Therefore, the reliability of the grid voltage and bus capacitance fault detection results can be guaranteed without increasing the hardware detection cost.

[0061] As can be seen, in this embodiment, to detect faults in the grid voltage and bus capacitance at the port side of the uncontrolled rectifier bridge, a line voltage measurement signal of the uncontrolled rectifier bridge is first obtained, and a six-pulse rectified voltage is constructed on the DC output side of the uncontrolled rectifier bridge under a disconnected condition based on the line voltage measurement signal. Then, an estimated bus voltage on the DC output side of the uncontrolled rectifier bridge is obtained based on the six-pulse rectified voltage. The pulsation amplitudes of the estimated bus voltage and the measured bus voltage at 300 Hz are respectively extracted to obtain a first pulsation amplitude and a second pulsation amplitude. The pulsation amplitude of the six-pulse rectified voltage at 100 Hz is also extracted to obtain a third pulsation amplitude. Subsequently, whether the bus capacitance on the DC output side of the uncontrolled rectifier bridge has aged is determined based on the first and second pulsation amplitudes. Finally, the DC component of the six-pulse rectified voltage is obtained, and whether an unbalanced grid voltage fault has occurred on the input side of the uncontrolled rectifier bridge is determined based on the DC component and the third pulsation amplitude. Compared with the existing technology, since this method does not require additional hardware detection circuits, it only requires some simple measurement signals and calculation transformations to determine whether the grid voltage and bus capacitance on the uncontrolled rectifier bridge port side are faulty, and will not be interfered by other factors. Therefore, the reliability of the grid voltage and bus capacitance fault detection results can be guaranteed without increasing the hardware detection cost.

[0062] Based on the above embodiment, this embodiment further illustrates and optimizes the technical solution. As a preferred implementation method, the above step of obtaining the line voltage measurement signal of the uncontrolled rectifier bridge and constructing the six-pulse rectified voltage of the DC output side of the uncontrolled rectifier bridge in the case of a circuit breaker according to the line voltage measurement signal includes:

[0063] Get the line voltage measurement signal u of the uncontrolled rectifier bridge RS 、u ST and u TR , and according to the first target model, the line voltage measurement signal u RS 、u ST and u TR Construct a six-pulse rectified voltage on the DC output side of the uncontrolled rectifier bridge in the case of a circuit breaker;

[0064] Among them, the expression of the first target model is:

[0065] u rect =max(|u RS |,|u ST |,|u TR |);

[0066] Where u rect is the six-pulse rectified voltage, u RS is the voltage between R phase and S phase on the uncontrolled rectifier bridge, u STis the voltage between phase S and phase T on the uncontrolled rectifier bridge, u TR It is the voltage value between T phase and R phase on the uncontrolled rectifier bridge.

[0067] See Figure 2 , Figure 2 When constructing the six-pulse rectified voltage on the DC output side of the uncontrolled rectifier bridge, the first step is to obtain the line voltage measurement signal u of the uncontrolled rectifier bridge. RS 、u ST and u TR , where u RS is the voltage between R phase and S phase on the uncontrolled rectifier bridge, u ST is the voltage between phase S and phase T on the uncontrolled rectifier bridge, u TR is the voltage value between phase T and phase R on the uncontrolled rectifier bridge; then, according to the first target model and the line voltage measurement signal u RS 、u ST and u TR To construct the six-pulse rectified voltage u of the DC output side of the uncontrolled rectifier bridge under the condition of circuit breaker rect .

[0068] As a preferred embodiment, the above step of obtaining the estimated bus voltage on the DC output side of the uncontrolled rectifier bridge according to the six-pulse rectified voltage includes:

[0069] Obtain an estimated bus voltage on the DC output side of the uncontrolled rectifier bridge according to the second target model and the six-pulse rectifier voltage;

[0070] Among them, the expression of the second target model is:

[0071]

[0072] Where, is the estimated bus voltage at time t, u rect is the six-pulse rectified voltage, R dc and C dc are the equivalent resistance and equivalent capacitance on the DC output side of the uncontrolled rectifier bridge respectively.

[0073] It is understandable that due to the influence of the tube voltage drop in the uncontrolled rectifier bridge and the parasitic resistance in the commutation circuit, there will be a certain deviation between the bus voltage on the DC output side of the uncontrolled rectifier bridge and the six-pulse rectified voltage. Therefore, in practical applications, the estimated bus voltage on the DC output side of the uncontrolled rectifier bridge can be equivalent to the low-pass filtering result of the six-pulse rectified voltage. Specifically, according to the second target model and the six-pulse rectified voltage u rect To obtain the estimated bus voltage u on the DC output side of the uncontrolled rectifier bridge dc .

[0074] Based on the above embodiment, this embodiment further illustrates and optimizes the technical solution. As a preferred implementation method, the above step of extracting the pulsation amplitudes of the estimated bus voltage and the measured bus voltage at 300 Hz to obtain the first pulsation amplitude and the second pulsation amplitude includes:

[0075] A second-order Butterworth filter is used to extract the estimated harmonic signal of the bus voltage at 300 Hz to obtain the first harmonic signal, and the absolute value operation and low-pass filtering are performed on the first harmonic signal to obtain the first pulsation amplitude;

[0076] The harmonic signal of the measured bus voltage at 300 Hz is extracted using a second-order Butterworth filter to obtain the second harmonic signal. The second harmonic signal is then subjected to absolute value calculation and low-pass filtering to obtain the second pulsation amplitude.

[0077] See Figure 3 , Figure 3 Schematic diagram for extracting the pulsation amplitude of the estimated bus voltage and the measured bus voltage. When extracting the pulsation amplitude of the estimated bus voltage at 300Hz, the cutoff frequency f of the second-order Butterworth filter can be first h Set it to 300Hz and set the cutoff frequency of the low-pass filter to f c Set to well below f h Thus, when extracting the estimated bus voltage pulsation amplitude at 300Hz, the second-order Butterworth filter can be used to extract the estimated bus voltage harmonic signal at 300Hz to obtain the first harmonic signal. Then, the absolute value function and low-pass filter are used to perform absolute value operation and low-pass filtering on the first harmonic signal to extract the estimated bus voltage pulsation amplitude U at 300Hz. recth6 .

[0078] When extracting the pulsation amplitude of the measured bus voltage at 300 Hz, the cutoff frequency f of the second-order Butterworth filter can be firstly set to h Set it to 300Hz and set the cutoff frequency of the low-pass filter to f c Set to well below f h In this way, when extracting the pulsation amplitude of the measured bus voltage at 300Hz, the second-order Butterworth filter can be used to extract the harmonic signal of the measured bus voltage at 300Hz to obtain the second harmonic signal. Then, the absolute value function and low-pass filter are used to perform absolute value operation and low-pass filtering on the second harmonic signal to extract the second pulsation amplitude U of the measured bus voltage at 300Hz. dch6 .

[0079] Similarly, when extracting the pulsation amplitude of the six-pulse rectifier voltage at 100Hz, the cutoff frequency f of the second-order Butterworth filter can be first h Set it to 100Hz and set the cutoff frequency of the low-pass filter to f c Set to well below f h In this way, when extracting the pulsation amplitude of the six-pulse rectified voltage at 100Hz, the second-order Butterworth filter can be used to extract the harmonic signal of the six-pulse rectified voltage at 100Hz to obtain the third harmonic signal. Then, the absolute value operation and low-pass filtering of the third harmonic signal can be performed on the third harmonic signal to extract the third pulsation amplitude U of the six-pulse rectified voltage at 100Hz. recth2 .

[0080] Based on the above embodiment, this embodiment further illustrates and optimizes the technical solution. As a preferred implementation method, the above step of determining whether the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged based on the first pulsation amplitude and the second pulsation amplitude includes:

[0081] If the first pulsation amplitude and the second pulsation amplitude meet the preset judgment condition, it is determined that the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged.

[0082] In practical applications, it is possible to determine whether the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aging by using a preset judgment condition. Specifically, the expression of the preset judgment condition is:

[0083]

[0084] Where U recth6 is the second pulsation amplitude, is the first pulsation amplitude.

[0085] That is, when the second pulsation amplitude U recth6 Greater than 2 times the first pulsation amplitude When the second pulsation amplitude U recth6 Less than or equal to 2 times the first pulsation amplitude This means that the bus capacitor on the DC output side of the uncontrolled rectifier bridge has not aged.

[0086] Obviously, when a mathematical model is used to determine whether the bus capacitor is aged, the aging determination result of the bus capacitor can be made more accurate and reliable.

[0087] Based on the above embodiment, this embodiment further illustrates and optimizes the technical solution. As a preferred implementation method, the above step of determining whether an unbalanced fault occurs in the grid voltage on the input side of the uncontrolled rectifier bridge based on the DC component and the third pulsating amplitude includes:

[0088] The third pulsation amplitude is normalized using the DC component as a reference value to obtain a target value;

[0089] If the target value is greater than the preset threshold, and the duration of the target value being greater than the preset threshold is greater than the preset duration, it is determined that an unbalanced fault occurs in the grid voltage on the input side of the uncontrolled rectifier bridge.

[0090] When determining whether an unbalanced grid voltage fault has occurred on the input side of the uncontrolled rectifier bridge, the third pulsation amplitude of the six-pulse rectifier voltage at 100 Hz can be first normalized using the DC component of the six-pulse rectifier voltage as a reference value to obtain a target value. If the target value is greater than a preset threshold and the duration of the target value exceeding the preset threshold is greater than the preset time, it indicates that an unbalanced grid voltage fault has occurred on the input side of the uncontrolled rectifier bridge. If the target value is less than the preset threshold, or if the target value is greater than the preset threshold but the duration of the target value exceeding the preset threshold is less than or equal to the preset time, it indicates that the grid voltage on the input side of the uncontrolled rectifier bridge is still balanced.

[0091] See Figure 4 , Figure 4 This is a structural diagram of a fault detection device for an uncontrolled rectifier bridge port provided by an embodiment of the present invention, the device comprising:

[0092] The voltage construction module 21 is used to obtain the line voltage measurement signal of the uncontrolled rectifier bridge and construct the six-pulse rectified voltage of the DC output side of the uncontrolled rectifier bridge in the circuit-breaking condition according to the line voltage measurement signal;

[0093] The voltage estimation module 22 is used to obtain the estimated bus voltage on the DC output side of the uncontrolled rectifier bridge according to the six-pulse rectified voltage;

[0094] an amplitude extraction module 23 for respectively extracting the pulsation amplitudes of the estimated bus voltage and the measured bus voltage at 300 Hz to obtain a first pulsation amplitude and a second pulsation amplitude, and extracting the pulsation amplitude of the six-pulse rectified voltage at 100 Hz to obtain a third pulsation amplitude;

[0095] A first judgment module 24 is used to determine whether the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged according to the first pulsation amplitude and the second pulsation amplitude;

[0096] The second judgment module 25 is used to obtain the DC component of the six-pulse rectified voltage and determine whether an unbalanced fault occurs in the grid voltage at the input side of the uncontrolled rectifier bridge according to the DC component and the third pulsation amplitude.

[0097] The embodiment of the present invention provides a device for detecting a fault on the port side of an uncontrolled rectifier bridge, which has the beneficial effects of the aforementioned method for detecting a fault on the port side of an uncontrolled rectifier bridge.

[0098] See Figure 5 , Figure 5 This is a structural diagram of a fault detection device on the port side of an uncontrolled rectifier bridge provided by an embodiment of the present invention, the device comprising:

[0099] Memory 31, for storing computer programs;

[0100] The processor 32 is configured to implement the steps of the aforementioned method for detecting a fault on the port side of an uncontrolled rectifier bridge when executing a computer program.

[0101] The embodiment of the present invention provides a device for detecting a fault on the port side of an uncontrolled rectifier bridge, which has the beneficial effects of the aforementioned method for detecting a fault on the port side of an uncontrolled rectifier bridge.

[0102] Correspondingly, an embodiment of the present invention further discloses a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the fault detection method on the port side of an uncontrolled rectifier bridge as disclosed above are implemented.

[0103] A computer-readable storage medium provided by an embodiment of the present invention has the beneficial effects of the aforementioned method for detecting faults on the port side of an uncontrolled rectifier bridge.

[0104] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0105] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0106] The above is a detailed introduction to the fault detection method, device, equipment and medium on the port side of an uncontrolled rectifier bridge provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for detecting a fault on the port side of an uncontrolled rectifier bridge, characterized in that: include: Acquire a line voltage measurement signal of an uncontrolled rectifier bridge, and construct a six-pulse rectified voltage of a DC output side of the uncontrolled rectifier bridge in an open circuit condition according to the line voltage measurement signal; Obtaining an estimated bus voltage on the DC output side of the uncontrolled rectifier bridge according to the six-pulse rectified voltage; extracting the pulsation amplitudes of the estimated bus voltage and the measured bus voltage at 300 Hz respectively to obtain a first pulsation amplitude and a second pulsation amplitude, and extracting the pulsation amplitude of the six-pulse rectified voltage at 100 Hz to obtain a third pulsation amplitude; determining whether the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged according to the first pulsating amplitude and the second pulsating amplitude; Obtaining a DC component of the six-pulse rectified voltage, and determining whether an unbalanced fault occurs in the grid voltage on the input side of the uncontrolled rectifier bridge according to the DC component and the third pulsation amplitude; The process of obtaining the line voltage measurement signal of the uncontrolled rectifier bridge and constructing the six-pulse rectified voltage of the DC output side of the uncontrolled rectifier bridge in the circuit-breaking state according to the line voltage measurement signal includes: Obtain the line voltage measurement signal u of the uncontrolled rectifier bridge RS 、u ST and u TR , and according to the first target model, the line voltage measurement signal u RS 、u ST and u TR Constructing the six-pulse rectified voltage at the DC output side of the uncontrolled rectifier bridge in a circuit-breaking condition; The expression of the first target model is: u rect =max(|u RS |,|u ST |,|u TR |); Where u rect is the six-pulse rectified voltage, u RS is the voltage between the R phase and the S phase on the uncontrolled rectifier bridge, u ST is the voltage between the S phase and the T phase on the uncontrolled rectifier bridge, u TR is the voltage value between the T phase and the R phase on the uncontrolled rectifier bridge; The process of obtaining the estimated bus voltage on the DC output side of the uncontrolled rectifier bridge according to the six-pulse rectified voltage includes: Obtaining the estimated bus voltage at the DC output side of the uncontrolled rectifier bridge according to the second target model and the six-pulse rectified voltage; The expression of the second target model is: Where, is the estimated bus voltage at time t, u rect is the six-pulse rectified voltage, R dc and C dc are respectively the equivalent resistance and equivalent capacitance of the DC output side of the uncontrolled rectifier bridge.

2. The fault detection method according to claim 1, characterized in that: The process of respectively extracting the pulsation amplitudes of the estimated bus voltage and the measured bus voltage at 300 Hz to obtain the first pulsation amplitude and the second pulsation amplitude includes: extracting a harmonic signal of the estimated bus voltage at 300 Hz using a second-order Butterworth filter to obtain a first harmonic signal, and performing an absolute value operation and a low-pass filter on the first harmonic signal to obtain the first pulsation amplitude; The harmonic signal of the measured bus voltage at 300 Hz is extracted using the second-order Butterworth filter to obtain a second harmonic signal, and the second harmonic signal is subjected to absolute value operation and low-pass filtering to obtain the second pulsation amplitude.

3. The fault detection method according to claim 1, characterized in that: The process of determining whether the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged according to the first pulsating amplitude and the second pulsating amplitude includes: If the first pulsating amplitude and the second pulsating amplitude meet a preset judgment condition, it is determined that the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged.

4. The fault detection method according to any one of claims 1 to 3, characterized in that: The process of determining whether an unbalanced fault occurs in the grid voltage at the input side of the uncontrolled rectifier bridge according to the DC component and the third pulsation amplitude includes: performing per-unit processing on the third pulsation amplitude with the DC component as a reference value to obtain a target value; If the target value is greater than a preset threshold value, and the duration for which the target value is greater than the preset threshold value is greater than a preset duration, it is determined that an unbalanced fault occurs in the grid voltage on the input side of the uncontrolled rectifier bridge.

5. A fault detection device for an uncontrolled rectifier bridge port, characterized in that: include: a voltage construction module, configured to obtain a line voltage measurement signal of an uncontrolled rectifier bridge and construct a six-pulse rectified voltage of a DC output side of the uncontrolled rectifier bridge in an open circuit condition according to the line voltage measurement signal; a voltage estimation module, configured to obtain an estimated bus voltage on the DC output side of the uncontrolled rectifier bridge according to the six-pulse rectified voltage; an amplitude extraction module, configured to extract the pulsation amplitudes of the estimated bus voltage and the measured bus voltage at 300 Hz, respectively, to obtain a first pulsation amplitude and a second pulsation amplitude, and to extract the pulsation amplitude of the six-pulse rectified voltage at 100 Hz, to obtain a third pulsation amplitude; a first judgment module, configured to determine whether the bus capacitor on the DC output side of the uncontrolled rectifier bridge is aged according to the first pulsation amplitude and the second pulsation amplitude; a second judgment module, configured to obtain a DC component of the six-pulse rectified voltage, and determine whether an unbalanced fault occurs in the grid voltage on the input side of the uncontrolled rectifier bridge according to the DC component and the third pulsation amplitude; The process of obtaining the line voltage measurement signal of the uncontrolled rectifier bridge and constructing the six-pulse rectified voltage of the DC output side of the uncontrolled rectifier bridge in the circuit-breaking state according to the line voltage measurement signal includes: Obtain the line voltage measurement signal u of the uncontrolled rectifier bridge RS 、u ST and u TR , and according to the first target model, the line voltage measurement signal u RS 、u ST and u TR Constructing the six-pulse rectified voltage at the DC output side of the uncontrolled rectifier bridge in a circuit-breaking condition; The expression of the first target model is: u rect =max(|u RS |,|u ST |,|u TR |); Where u rect is the six-pulse rectified voltage, u RS is the voltage between the R phase and the S phase on the uncontrolled rectifier bridge, u ST is the voltage between the S phase and the T phase on the uncontrolled rectifier bridge, u TR is the voltage value between the T phase and the R phase on the uncontrolled rectifier bridge; The process of obtaining the estimated bus voltage on the DC output side of the uncontrolled rectifier bridge according to the six-pulse rectified voltage includes: Obtaining the estimated bus voltage at the DC output side of the uncontrolled rectifier bridge according to the second target model and the six-pulse rectified voltage; The expression of the second target model is: Where, is the estimated bus voltage at time t, u rect is the six-pulse rectified voltage, R dc and C dc are respectively the equivalent resistance and equivalent capacitance of the DC output side of the uncontrolled rectifier bridge.

6. A fault detection device for an uncontrolled rectifier bridge port, characterized in that: include: memory for storing computer programs; A processor is configured to implement the steps of a method for detecting a fault on the port side of an uncontrolled rectifier bridge as claimed in any one of claims 1 to 4 when executing the computer program.

7. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for detecting a fault on the port side of an uncontrolled rectifier bridge are implemented as described in any one of claims 1 to 4.

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