Online fault judgment method for rotating rectifier diode of three-stage generator

Abstract

The invention belongs to the technical field of aviation power supply system control, and particularly relates to a three-stage generator rotating rectifier diode fault online judgment method. According to the method, in the power generation process of the three-stage generator, through extraction and amplitude calculation of an alternating current component in stator current of an exciter, whether an open circuit or short circuit fault occurs in a rotary rectifier diode of the three-stage generator is judged based on the amplitude.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aviation power system control, and particularly relates to a method for judging the fault of a rotating rectifier diode of a three-stage generator. BACKGROUND

[0002] The three-stage generator is widely used in the aircraft power system due to its mature technology, the fault extinguishing magnetism in the power generation process and the like, and the three-stage generator mainly comprises a permanent magnet machine, an exciter, a rotating rectifier and a main generator, the rotors of the permanent magnet machine, the exciter and the main generator are coaxially installed, and a principle structure diagram is shown in Figs. Figure 1 and 2 The rotating rectifier is composed of six identical diodes, and is installed on the rotor side to rectify the three-phase alternating current induced on the exciter rotor into direct current, and is usually referred to as a rotating rectifier diode. In the power generation process, the engine drives the three-stage generator to rotate, the permanent magnets on the permanent magnet rotor cut the permanent magnet electronic winding to generate three-phase alternating current, the three-phase alternating current is controlled by the generator controller, and the direct current with adjustable duty cycle is output as the excitation voltage of the exciter stator, the excitation voltage induces three-phase alternating current on the rotating exciter rotor and generates three-phase current, the three-phase current is rectified by the rotating rectifier to provide excitation current for the main generator, the excitation magnetic field is formed, and the rotating excitation magnetic field cuts the main generator stator winding to generate three-phase alternating current. The generator controller adjusts the excitation voltage in real time according to the size of the on-board load, so that the three-phase alternating current generated by the main generator remains stable.

[0003] The three-stage generator is installed in the engine compartment and connected with the engine through the accessory machine case, and the working environment is relatively harsh. The rotating rectifier diode is one of the few electronic devices in the three-stage generator, and its failure rate is usually higher than that of other parts of the generator in the high-temperature and strong-vibration environment. Meanwhile, since the rotating rectifier diode is installed on the rotor side, it is impossible to judge whether the state is good or not by directly measuring the characteristic signal thereof.

[0004] After the rotating rectifier diode fails, the exciter stator current fluctuates, and the power generation voltage pulsation increases. The method for judging whether the diode fails by the voltage pulsation has a high false alarm rate and a long judgment process, and the generator rotor winding is easily damaged when the diode short-circuit fault occurs.

[0005] In the existing public literature, researchers have proposed to realize it by detecting the harmonic content of the exciter stator current or estimating the exciter rotor current. Such a method has a relatively complex algorithm and a high requirement for the system hardware conditions, and the effect is poor in engineering application. In this paper, the working state of the diode is judged by the change of the alternating current signal amplitude in the exciter stator current, the algorithm is simple, and no additional hardware conditions are needed. SUMMARY

[0006] OBJECTIVE OF THE INVENTION Aiming at the online fault judgment problem of rotating rectifier diode of three-stage generator, based on the existing hardware conditions, through algorithm improvement design, the alternating current component of exciter stator current is extracted and the amplitude is calculated, whether the rotating rectifier diode appears open circuit or open circuit fault is judged online according to the amplitude change, and corresponding fault disposal measures can be made according to the current state of the aircraft, so as to avoid irreversible damage of on-board equipment caused by diode fault.

[0007] Technical scheme: A kind of rotating rectifier diode fault online judgment method of three-stage generator, in the process of three-stage generator power generation, the alternating current component in exciter stator current is extracted and the amplitude is calculated, whether the rotating rectifier diode of three-stage generator appears open circuit or short circuit fault is judged based on the amplitude.

[0008] Further, comprising: Step 1: set the open circuit fault current comparison threshold for judging diode fault , open circuit judgment time , short circuit fault current comparison threshold , short circuit judgment time ; Step 2: the three-stage motor is accelerated to a certain speed in the power generation speed range, which is recorded as ; Step 3: give power generation command, generator controller carries out closed loop voltage regulation, provides excitation voltage to exciter stator, at the same time, collects exciter stator current through internal conditioning circuit, which is recorded as ; Step 4: the excitation current is filtered and the alternating current component in the excitation current is extracted, which is recorded as ; Step 5: the alternating current component is taken absolute value, which is recorded as , and is calculated by equivalent mean value, which is recorded as ; Step 6: according to and , , , , determine whether the diode is faulty.

[0009] Further, in step 1, wherein is greater than .

[0010] Further, in step 4, a high-pass filter is used to filter the excitation current and extract the alternating current component in the excitation current, which is recorded as .

[0011] Further, the equivalent mean value calculation processing in step 5 is equivalent to the formula as follows:

[0012] wherein, , is the current time value, is the last time value, is the equivalent processing coefficient.

[0013] 6. The method of claim 5, wherein, is in the range of [0, 1].

[0014] Further, step 6 is specifically as follows: Step 6.1: if ≤ , it indicates that the diode is in normal state, and the state indication code is set to 0; Step 6.2: if < < , and the duration is greater than , it indicates that the diode has an open circuit fault, and the state indication code is set to 1; Step 6.3: if ≥ , and the duration is greater than , it indicates that the diode has a short circuit fault, and the state indication code is set to 2.

[0015] Further, in step 1, the open circuit fault current comparison threshold is 0.15A.

[0016] Further, in step 1, the open circuit judgment time is 100ms.

[0017] Further, in step 1, the short circuit fault current comparison threshold is 1A, and the short circuit judgment time is 10ms.

[0018] Beneficial effects: The application proposes a three-stage generator rotating rectifier diode fault online judgment method. Without increasing hardware resources, the extraction of the alternating current component of the exciter stator current and the equivalent amplitude calculation are realized through algorithm improvement, and whether the diode has a short circuit and open circuit fault is judged online according to the size of the equivalent amplitude, which effectively reduces the risk of secondary damage to on-board equipment caused by the system running with disease, and improves the safety of the system. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. The drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0020] Figure 1 Fig. 3 is a schematic diagram of a three-stage generator structure.

[0021] Figure 2 Fig. 4 is a schematic diagram of a power generation control principle.

[0022] Figure 3 Fig. 5 is a related waveform from normal to open circuit of a rotary rectifier diode (no load).

[0023] Figure 4 Fig. 6 is a related waveform from normal to open circuit of a rotary rectifier diode (full load).

[0024] Figure 5 Fig. 7 is a related waveform from normal to short circuit of a rotary rectifier diode (no load).

[0025] Figure 6 Fig. 8 is a related waveform from normal to short circuit of a rotary rectifier diode (full load). DETAILED DESCRIPTION

[0026] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will combine the drawings in the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0027] The features and illustrative embodiments of various aspects of the present application will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one of ordinary skill in the art that the present application can be practiced without some or all of these specific details. The description of the embodiments is merely provided to give a better understanding of the present application by showing examples of the present application. The present application is in no way limited to any specific settings and methods presented below, but covers any improvements, replacements and modifications of structures, methods and devices without departing from the spirit of the present application. In the drawings and the following description, well-known structures and technologies are not shown to avoid unnecessary obscuring of the present application.

[0028] In the description of the present application, it should be noted that the directions or positional relationships belonging to the indications of "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like are the directions or positional relationships described based on the drawings, which are only for the convenience of describing the present application and simplifying the description, and cannot be understood as a limitation on the present application. In addition, the ordinal numbers (for example, "first" and "second") are used to distinguish objects, and are not limited to the order, and cannot be understood as indicating or implying relative importance.

[0029] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms of "mounting", "connecting", "connecting" should be understood in a broad sense, which can be directly connected or indirectly connected through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0030] It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other, and each embodiment can be mutually referred to and quoted. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0031] The present application will be further described in detail below in combination with the embodiments and the drawings, but the embodiments of the present application are not limited thereto.

[0032] The present application relates to a kind of tertiary generator rotating rectifier diode fault online judgment method proposed in the present application, in the process of generating electricity in tertiary generator, by extracting and amplitude calculation to the alternating current component in the field current of exciter, based on the size of amplitude judges whether tertiary generator rotating rectifier diode appears open circuit or short circuit fault.

[0033] Embodiment 1: The present application will be further described in combination with embodiment 1 and the drawings, and the specific steps contained in embodiment 1 are as follows: Step 1: set the current comparison threshold for judging diode open circuit fault to 0.15A, the judgment time is 100ms, the current comparison threshold for judging short circuit fault is 1A, and the judgment time is 10ms; Step 2: set the motor running speed as =20000r / min; Step 3: give the power generation command, the generator controller carries out closed loop voltage regulation, provides excitation voltage to the exciter stator, and at the same time, collects the excitation current of the exciter stator (denoted as ) through internal conditioning circuit, at normal power generation operation 0.3s, one diode in rotating rectifier is changed from normal to open circuit fault; Step 4: The stator current of the exciter is filtered by using a 2-order high-pass filter with a cutoff frequency of 100 Hz to extract the AC component of the excitation current ; Step 5: The AC component is subjected to absolute value processing (denoted as ), and is subjected to equivalent mean value calculation processing (denoted as ). The formula is as follows:

[0034] Among them, , is the current time value, is the previous time value, = 0.98; Step 6: Compare with , according to the state set in step 4, the rotating rectifier diode works normally 0.3s ago, , the diode is open-circuit fault at 0.3s, , after 100ms, the diode state is updated from normal to open-circuit fault, and the state indication code changes from 0 to 1; Figure 3 and Figure 4 are the open-circuit fault recognition results of the diode under no-load and 120kVA load (rated load) conditions, respectively, which illustrate the effectiveness of the method.

[0035] Example 2: The application is further described in combination with Example 2 and the accompanying drawings. The specific steps included in Example 2 are as follows: Step 1: Set the current comparison threshold for judging the open-circuit fault of the diode as 0.15A and the judgment time as 100ms, and set the current comparison threshold for judging the short-circuit fault as 1A and the judgment time as 10ms; Step 2: Set the running speed of the motor as = 20000r / min; Step 3: Give a power generation command, and the generator controller performs closed-loop voltage regulation to provide excitation voltage to the exciter stator. Meanwhile, the exciter stator current (denoted as ) is collected through the internal conditioning circuit. At 0.3s of normal power generation operation, one diode in the rotating rectifier is changed from normal to short-circuit fault; Step 4: The stator current of the exciter is filtered by using a 2-order high-pass filter with a cutoff frequency of 100 Hz to extract the AC component of the excitation current ​​​; Step 5: absolute value processing (denoted as ) is performed on the alternating component, and is subjected to equivalent mean value calculation (denoted as ), and the formula used is as follows:

[0036] wherein, , is the current time value, is the previous time value, = 0.98; Step 6: comparison is made between and , , and according to the state set in Step 4, the rotating rectifier diode works normally 0.3s ago, , the diode is in short-circuit fault at 0.3s, , and after 10ms, the diode state is updated from normal to short-circuit fault, and the state indication code is changed from 0 to 2; Figure 5 and Figure 6 are respectively the diode short-circuit fault recognition results under no-load and 120kVA load (rated load) conditions, which illustrate the effectiveness of the method.

[0037] The above is merely a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which shall be encompassed in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.​​

Claims

1. A method for online fault diagnosis of rotating rectifier diodes in a three-stage generator, characterized in that, During the power generation process of a three-stage generator, the AC component in the exciter stator current is extracted and its amplitude is calculated. Based on the magnitude of the amplitude, it is determined whether the rotating rectifier diode of the three-stage generator has an open circuit or short circuit fault.

2. The method according to claim 1, characterized in that, include: Step 1: Set the open-circuit fault current comparison threshold for determining diode faults. Road opening judgment time Short-circuit fault current comparison threshold Short circuit detection time ; Step 2: Speed ​​up the three-pole motor to a speed within the generator speed range, denoted as . ; Step 3: Upon receiving the power generation command, the generator controller performs closed-loop voltage regulation to provide excitation voltage to the exciter stator. Simultaneously, it collects the exciter stator current through its internal conditioning circuit, denoted as... ; Step 4: Filter the exciter stator current and extract the AC component from the excitation current, denoted as... ; Step 5: Take the absolute value of the AC component, denoted as . Then Perform equivalent mean calculation, denoted as ; Step 6: According to as well as , , , To determine if the diode is faulty.

3. The method according to claim 2, characterized in that, In step 1, where, Greater than .

4. The method according to claim 3, characterized in that, Step 4: Use a high-pass filter to filter the exciter stator current and extract the AC component of the excitation current, denoted as . .

5. The method according to claim 4, characterized in that, Step 5 involves equivalent mean calculation, using the following formula: in, , This is the value at the current time. The value at the previous time step. This is the equivalent treatment coefficient.

6. The method according to claim 5, characterized in that, The range of is [0,1].

7. The method according to claim 6, characterized in that, Step 6, specifically: Step 6.1: If ≤ This indicates that the diode is in normal condition, and the status indicator code is set to 0; Step 6.2: If < < And the duration is greater than If the value is 1, it indicates that the diode has an open circuit fault, and the status indicator code is set to 1. Step 6.3: If ≥ And the duration is greater than If the value is 0, it indicates that the diode has a short circuit fault, and the status indicator code is set to 2.

8. The method according to claim 6, characterized in that, In step 1, the open-circuit fault current comparison threshold is... It is 0.15A.

9. The method according to claim 7, characterized in that, In step 1, the open-circuit judgment time It takes 100ms.

10. The method according to claim 9, characterized in that, In step 1, the short-circuit fault current comparison threshold is... 1A, short circuit judgment time It takes 10ms.

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