Exciter machine resonance overvoltage fault analysis system, method, storage medium and electronic device

Abstract

The present application relates to a kind of excitation machine resonance overvoltage fault analysis system, method, storage medium and electronic equipment, comprising: excitation current acquisition unit, for acquiring the excitation current of excitation loop;Excitation current analysis unit is used to analyze excitation current, obtain the harmonic component of excitation current;Simulation unit is used to simulate analysis to excitation system, to obtain preset harmonic;Fault analysis unit is used to compare according to harmonic component and preset harmonic, and according to the result of comparison, excitation machine fault is analyzed.The present application is analyzed by excitation current, and it is compared with reference to preset harmonic to determine whether excitation machine occurs resonance, so that it can be analyzed according to the result of comparison whether excitation machine occurs fault and fault reason, avoid excitation system due to resonance overvoltage and damage equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of the excitation system of the unit, more particularly to an excitation machine resonance overvoltage fault analysis system, method, storage medium and electronic device. BACKGROUND

[0002] Under normal working conditions, the excitation power comes from the excitation transformer at the generator end, which is transmitted to the stator magnetic pole of the excitation machine after being rectified by the AVR three-phase thyristor rectifier bridge. The rotor of the excitation machine cuts the stator magnetic field, thereby generating an alternating current. The alternating current is rectified by the rotating rectifier (rotating diode) and supplied to the generator rotor coil winding to establish the generator magnetic field.

[0003] To solve the problem that the system strong excitation is affected after the short circuit of the power grid, a 220V DC auxiliary strong excitation power supply is arranged in the excitation system. When the controllable silicon rectifier circuit cannot meet the strong excitation when the generator end voltage drops to 70% under accident working conditions, the auxiliary strong excitation power supply is automatically put into operation to meet the requirements of the generator strong excitation.

[0004] The DC system insulation monitor uses a balanced bridge resistor to measure the busbar insulation, and the balanced bridge is connected to the positive and negative poles of the busbar.

[0005] In a certain A nuclear power plant in a certain month of a certain year, during the operation of the No. 3 unit, the main control triggered multiple alarms of the DC system, and then the unit tripped. Subsequently, the electrical personnel found that the DC system insulation monitor was burned out after on-site inspection. After the excitation machine magnetic pole was pulled out, it was found that the felt between the magnetic pole coil and the iron core was broken down and carbonized, causing a single ground.

[0006] The actual on-site inspection found that the excitation machine equipment and the DC system equipment had been burned out. Therefore, it is necessary to invent an excitation machine fault analysis system to analyze the mechanism of the above-mentioned excitation system fault.

[0007] In view of the above-mentioned fault problem, the existing excitation system is prone to resonance high voltage in the auxiliary strong excitation circuit composed of the excitation machine magnetic pole, the excitation rectifier and the battery when the excitation machine magnetic pole winding ground fault occurs, which causes the equipment to be broken down and shut down.

[0008] The existing excitation system only points out that the resonance overvoltage of the auxiliary strong circuit breaks down the equipment, but cannot analyze and verify the mechanism of the resonance overvoltage. SUMMARY

[0009] The technical problem to be solved by the present application is to provide an excitation machine fault analysis system, method, storage medium and electronic device in view of the defects of the prior art.

[0010] The technical solution adopted by the present application to solve the technical problem is: an excitation machine fault analysis system is constructed, which comprises:

[0011] The excitation current collection unit is configured to collect an excitation current of an excitation loop.

[0012] The excitation current analysis unit is configured to analyze the excitation current and obtain a harmonic component of the excitation current.

[0013] The simulation unit is configured to perform simulation analysis on the excitation system to obtain a preset harmonic.

[0014] The fault analysis unit is configured to compare the harmonic component with the preset harmonic, and analyze the excitation machine fault according to a comparison result.

[0015] In the excitation machine fault analysis system, the simulation unit comprises:

[0016] The modeling parameter collection module is configured to collect modeling parameters of the excitation loop.

[0017] The modeling module is configured to establish an excitation simulation model according to the modeling parameters.

[0018] In the excitation machine fault analysis system, the simulation unit further comprises:

[0019] The ground fault analysis module is configured to simulate normal operation and various ground fault states of the excitation system based on the excitation simulation model, to obtain harmonic characteristic frequencies and resonance voltage values of the excitation current corresponding to the normal operation and various fault states of the excitation system.

[0020] In the excitation machine fault analysis system, the simulation unit further comprises:

[0021] The resonance analysis module is configured to perform resonance overvoltage fault analysis on the excitation system to obtain the preset harmonic.

[0022] The application further provides an excitation machine fault analysis method, comprising the following steps:

[0023] Performing simulation analysis on the excitation system to obtain a preset harmonic.

[0024] Collecting an excitation current of an excitation loop.

[0025] Analyzing the excitation current and obtaining a harmonic component of the excitation current.

[0026] Comparing the harmonic component with a preset harmonic, and analyzing the excitation machine fault according to a comparison result.

[0027] In the excitation machine fault analysis method, the method further comprises:

[0028] Collect modeling parameters of the excitation loop;

[0029] Establish an excitation simulation model according to the modeling parameters.

[0030] In the exciter fault analysis method, the method further comprises: simulating normal operation and various grounding fault states of the excitation system based on the excitation simulation model to obtain harmonic characteristic frequencies and resonance voltage values of the excitation current corresponding to the normal operation and various fault states of the excitation system.

[0031] In the exciter fault analysis method, the method further comprises:

[0032] Performing resonance overvoltage fault analysis on the excitation system to obtain the preset harmonic.

[0033] The application further provides a storage medium having a computer program stored thereon, and the computer program is executed by a processor to implement the steps of the method.

[0034] The application further provides an electronic device, comprising at least one processor, and a memory in communication connection with the at least one processor.

[0035] The memory stores instructions executable by the at least one processor, and the instructions are configured to execute the above method.

[0036] The exciter fault analysis system, method, storage medium and electronic device of the application have the following beneficial effects: the exciter fault analysis system comprises an excitation current collection unit for collecting excitation current of an excitation loop, an excitation current analysis unit for analyzing the excitation current to obtain harmonic components of the excitation current, a simulation unit for performing simulation analysis on the excitation system to obtain a preset harmonic, and a fault analysis unit for comparing the harmonic components with the preset harmonic and analyzing exciter faults according to the comparison result. The application analyzes the excitation current and compares the result with the preset harmonic to determine whether the exciter resonates, so that the exciter faults and fault causes can be analyzed according to the comparison result, and the excitation system is prevented from damaging the equipment due to resonance overvoltage. BRIEF DESCRIPTION OF DRAWINGS

[0037] The application will be further described below with reference to the drawings and embodiments, and the drawings are as follows:

[0038] Figure 1 FIG. 1 is a structural schematic diagram of an exciter fault analysis system provided by an embodiment of the application;

[0039] Figure 2 FIG. 2 is a principle diagram of an excitation system of a generator provided by an embodiment of the application;

[0040] Figure 3 is a schematic diagram of a three-phase thyristor bridge provided by an embodiment of the application;

[0041] Figure 4 is a schematic diagram of a DC side voltage of a three-phase thyristor bridge provided by an embodiment of the application;

[0042] Figure 5 is a Fourier decomposition schematic diagram of a DC side voltage of a three-phase thyristor bridge provided by an embodiment of the application;

[0043] Figure 6 is an equivalent circuit diagram of a resonance circuit of a three-phase thyristor bridge provided by an embodiment of the application;

[0044] Figure 7 is a simplified equivalent circuit diagram of a resonance circuit of a three-phase thyristor bridge provided by an embodiment of the application;

[0045] Figure 8 is a further simplified equivalent circuit diagram of a resonance circuit of a three-phase thyristor bridge provided by an embodiment of the application;

[0046] Figure 9 is a schematic diagram of an exciter excitation current provided by an embodiment of the application;

[0047] Figure 10 is a schematic diagram of a DC negative bus voltage to ground provided by an embodiment of the application;

[0048] Figure 11 is a schematic diagram of a positive pole of an excitation winding to ground provided by an embodiment of the application;

[0049] Figure 12 is a schematic diagram of a negative pole of an excitation winding to ground provided by an embodiment of the application;

[0050] Figure 13 is a schematic diagram of an exciter excitation current in a resonance condition provided by an embodiment of the application;

[0051] Figure 14 is a schematic diagram of a positive pole of an excitation winding to ground in a resonance condition provided by an embodiment of the application;

[0052] Figure 15 is a schematic diagram of a negative pole of an excitation winding to ground in a resonance condition provided by an embodiment of the application;

[0053] Figure 16 is a simplified circuit schematic diagram of an excitation system after an auxiliary strong excitation circuit is cancelled;

[0054] Figure 17 is a schematic diagram of an exciter excitation current after an auxiliary strong excitation circuit is cancelled;

[0055] Figure 18 is the enlarged schematic diagram of the exciter current of the exciter at t=6~8s after the auxiliary strong excitation circuit is cancelled;

[0056] Figure 19 is the schematic diagram of the positive pole-to-ground voltage of the excitation winding after the auxiliary strong excitation circuit is cancelled;

[0057] Figure 20 is the schematic diagram of the negative pole-to-ground voltage of the excitation winding after the auxiliary strong excitation circuit is cancelled;

[0058] Figure 21 is the flowchart of the exciter fault analysis method provided by the embodiment of the present application;

[0059] Figure 22 is the flowchart of the simulation analysis provided by the embodiment of the present application. DETAILED DESCRIPTION

[0060] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described in detail with reference to the drawings.

[0061] The present application, without affecting the stable operation of the unit and without changing the structure of the unit, establishes a large nuclear power unit excitation system simulation platform based on MATLAB / Simulink software, can systematically and comprehensively reflect the electromagnetic transient performance of the internal faults of the generator and its excitation system, reproduce the change rule of the electrical quantity during the excitation system equipment fault, demonstrates the mechanism of the common-mode resonance overvoltage caused by the common ground of the excitation system main loop and the DC system common ground induced loop, and based on the mechanism, analyzes the fault of the exciter, so as to accurately and reliably analyze the fault cause of the exciter and avoid the damage of the equipment due to the resonance overvoltage of the excitation system.

[0062] Specifically, referring to Figure 1 , the structure schematic diagram of an optional embodiment of the exciter fault analysis system provided by the present application is shown.

[0063] As shown in Figure 1 , the exciter fault analysis system comprises:

[0064] The excitation current acquisition unit 101 is configured to acquire the excitation current of the excitation circuit.

[0065] Optionally, in the embodiment of the present application, the excitation circuit comprises: a generator, an excitation transformer, an automatic voltage regulator (AVR), a silicon controlled rectifier bridge and an exciter pole winding. That is, as shown in Figure 2 . Wherein, the acquisition of the excitation current can be realized by any existing way.

[0066] The excitation current analysis unit 102 is configured to analyze the excitation current and obtain the harmonic component of the excitation current.

[0067] Optionally, in the embodiment of the present application, the harmonic components include but are not limited to a direct current component (0 Hz), a 6th harmonic component (300 Hz), a 12th harmonic component (600 Hz), etc.

[0068] The simulation unit 100 is configured to perform simulation analysis on the excitation system to obtain preset harmonics.

[0069] The fault analysis unit 103 is configured to compare the harmonic components with the preset harmonics, and analyze the exciter fault according to the comparison result.

[0070] Optionally, in the embodiment of the present application, the simulation unit 100 includes a modeling parameter acquisition module configured to acquire modeling parameters of the excitation circuit, and a modeling module configured to establish an excitation simulation model according to the modeling parameters.

[0071] Optionally, the modeling parameters include excitation circuit information, auxiliary circuit information, and DC insulation detector information. The excitation circuit information includes but is not limited to a rotor type of the generator, a pole number of the generator, a transient state of the generator, a sub-transient state of the generator, a steady-state reactance of the generator, a short-circuit characteristic curve of the generator, a no-load characteristic curve of the generator, an excitation current of the excitation circuit, an inductance of the exciter, a capacitance, etc. The auxiliary circuit information includes but is not limited to a voltage, a current, and a capacity of the battery pack, etc. The DC insulation detector information includes a resistance value of a balancing resistor.

[0072] Optionally, in the embodiment of the present application, the simulation unit 100 further includes a ground fault analysis module configured to simulate normal operation and various ground fault states of the excitation system based on the excitation simulation model, to obtain harmonic characteristic frequencies and resonance voltage values of the excitation current corresponding to the normal operation and the various fault states of the excitation system.

[0073] Optionally, in the embodiment of the present application, the simulation unit 100 further includes a resonance analysis module configured to perform resonance overvoltage fault analysis on the excitation system to obtain the preset harmonics.

[0074] Reference Figure 21 is a flowchart of an optional embodiment of the exciter fault analysis method provided by the present application.

[0075] As Figure 21 shown, the exciter fault analysis method includes the following steps:

[0076] Step S21, performing simulation analysis on the excitation system to obtain preset harmonics.

[0077] Optionally, in the embodiment of the present application, as Figure 22 shown, the simulation analysis on the excitation system to obtain the preset harmonics includes:

[0078] Step S211, collect modeling parameters of the excitation loop.

[0079] Step S212, establish an excitation simulation model according to the modeling parameters.

[0080] Step S213, simulate normal operation and various grounding fault states of the excitation system based on the excitation simulation model to obtain harmonic characteristic frequencies and resonance voltage values of the excitation current under normal operation and various fault states of the excitation system.

[0081] Optionally, in the embodiment of the present application, the harmonic characteristic frequencies include a direct current component (0 Hz), a 6th harmonic (300 Hz), and a 12th harmonic (600 Hz). The corresponding resonance voltage values are 88 V, 130 V, and 57 V, respectively.

[0082] Step S214, perform resonance overvoltage fault analysis on the excitation system to obtain a preset harmonic. Specifically, in this step, the resonance overvoltage fault analysis is performed on the excitation system according to the harmonic characteristic frequencies and resonance voltage values obtained in step S213 to obtain a preset harmonic.

[0083] Step S22, obtain the excitation current of the excitation loop.

[0084] Step S23, analyze the excitation current to obtain a harmonic component of the excitation current.

[0085] Step S24, compare the harmonic component with a preset harmonic, and analyze the excitation machine fault according to the comparison result.

[0086] Optionally, in the embodiment of the present application, the preset harmonic is 300 Hz. Specifically, after obtaining the harmonic component, the obtained harmonic component is compared with the preset harmonic. If the harmonic component is equal to the preset harmonic, it indicates that the excitation loop enters a resonance state. At this time, the positive pole-to-ground voltage of the excitation winding of the excitation machine or the negative pole-to-ground voltage of the excitation winding of the excitation machine is synchronously obtained. If the positive pole-to-ground voltage of the excitation winding of the excitation machine or the negative pole-to-ground voltage of the excitation winding of the excitation machine reaches 1000 V, an excitation winding grounding fault alarm is output. If the positive pole-to-ground voltage of the excitation winding of the excitation machine or the negative pole-to-ground voltage of the excitation winding of the excitation machine reaches 1500 V, an excitation winding grounding fault alarm is output, and the auxiliary auxiliary overexcitation circuit is controlled to be disconnected.

[0087] Specifically, two conditions must be met for a resonant overvoltage situation to occur: first, there must be a resonant source with sufficient energy; second, a resonant circuit must exist. Since the exciter stator circuit is designed as an ungrounded system, and the DC system is also ungrounded, unstable grounding points may occur in the circuit, potentially leading to multiple grounding inductions and abnormal currents. Different RC circuits connected in series and parallel may form a resonant circuit at a specific frequency. Therefore, this invention uses frequency derivation (which may include actual capacitance measurement) and the setting of fault points at different locations to model and simulate the auxiliary excitation circuit (i.e., the auxiliary circuit) in simulation unit 100 to verify the overvoltage problem.

[0088] like Figure 2 As shown ( Figure 2 In this diagram, LAB represents a DC system and AVR represents an automatic voltage regulator. Analysis confirms that only DC components exist in the positive and negative buses, battery, charger, and excitation winding of the system, which will not cause resonance. The generator inputs three-phase AC power into the thyristor rectifier bridge: the rectified power is then output to the load side (the excitation winding of the exciter). The DC side voltage of the thyristor rectifier bridge contains abundant harmonic components, which can provide an AC source for resonance. Based on this principle, the simulation unit 100 of this invention performs resonance simulation analysis. The connection diagram of the three-phase thyristor rectifier bridge is shown below. Figure 3 As shown in the figure. In the excitation simulation model, it can be assumed that an unstable grounding point may occur at the midpoint of the excitation winding of the exciter. Therefore, the excitation winding is equivalently decomposed into two identical RL series parts, and a grounding fault point is set in the middle through a switch.

[0089] Specifically, the DC side of a three-phase thyristor rectifier bridge can be equivalent to a low-frequency resonant power supply containing sufficiently high energy. During normal operation, the DC side voltage of the three-phase full-bridge thyristor rectifier bridge is as follows: Figure 4 As shown. From Figure 4 As can be seen, the DC voltage of the three-phase full-bridge thyristor rectifier bridge is a DC component (88V) superimposed with an AC component that fluctuates over one period. Fourier analysis of this DC voltage yields... Figure 5 A breakdown diagram. (From...) Figure 5 It can be seen that the DC component (0Hz) of this voltage is approximately 88V, the 6th harmonic (300Hz) is approximately 130V, and the 12th harmonic (600Hz) is approximately 57V. Among these, the amplitude of the higher harmonic voltages gradually decreases, and the energy also gradually decays. Even if resonance occurs, it will not generate excessively high voltages that could endanger the safety of the equipment. Figure 5 It can be seen that the 6th and 12th harmonic voltages have relatively high amplitudes and sufficient energy, possessing the ability to induce circuit resonance and cause overvoltage. Based on this simulation analysis result, this invention further conducts simulation analysis on the resonant circuit.

[0090] Specifically, if a grounding point (or unstable grounding point) appears in the middle of the exciter field winding, multiple resonance loops will appear in the system, as shown in the system diagram in FIG. 1. Figure 2 As shown in the system diagram in FIG. 1, at this time, the following four grounding points can appear in the system: 1) one high-resistance grounding point of the insulation monitor; 2) two grounding points of the cable-to-ground capacitance; and 1) one grounding point of the exciter field winding.

[0091] The four grounding points can form four loops, as shown in FIG. 2, which are as follows. Figure 6

[0092] Loop 1: positive pole of the DC side of the three-phase thyristor rectifier bridge → exciter inductance Lm1 → grounding point of the exciter field winding → grounding point of the insulation monitor → R- → DC negative bus → DC interval switch → L1 (equivalent inductance of the cable between the interval switch and the switch GEX205JA) → GEX205JA (switch) → negative pole of the DC side of the three-phase thyristor rectifier bridge.

[0093] Loop 2: positive pole of the DC side of the three-phase thyristor rectifier bridge → exciter inductance Lm1 → grounding point of the exciter field winding → grounding point of the insulation monitor → R+ → DC positive bus → positive pole of the battery → negative pole of the battery → DC interval switch → L1 → GEX205JA → negative pole of the DC side of the three-phase thyristor rectifier bridge.

[0094] Loop 3: positive pole of the DC side of the three-phase thyristor rectifier bridge → exciter inductance Lm1 → grounding point of the exciter field winding → C5 → GEX205JA → negative pole of the DC side of the three-phase thyristor rectifier bridge.

[0095] Loop 4: positive pole of the DC side of the three-phase thyristor rectifier bridge → exciter inductance Lm1 → grounding point of the exciter field winding → C4 → DC positive bus → positive pole of the battery → negative pole of the battery → DC interval switch → L1 → GEX205JA → negative pole of the DC side of the three-phase thyristor rectifier bridge.

[0096] In the above four resonance loops, resonance loops 1 and 2 pass through the large resistors R+ and R- of the insulation monitor, so the resonance energy of the two loops is easily absorbed and attenuated by the large resistors, and even if resonance occurs, it will not cause an overvoltage situation. Therefore, the simulation unit 100 of the present application further simplifies the simulation model to obtain the simplified diagram shown in FIG. 3. Figure 7

[0097] Figure 7 ​​In the formula, Rm is the total resistance of the exciter field winding, the actual Rm is 1.15267 Ω; Lm is the total inductance of the exciter field winding, the actual Lm is 0.5 H; Zg is the equivalent impedance of the excitation winding to ground; C4 and C5 are the equivalent capacitances of the system positive to ground and negative to ground respectively as viewed from the AVR rectifier bridge side; C is the equivalent capacitance of the system to ground as viewed from the DC side of the AVR rectifier bridge (i.e. the battery pack + DC system bus + auxiliary strong excitation cable + DC insulation monitor + AVR power bridge DC bus + the capacitance of the exciter to ground + the capacitance of the exciter grounding fault point + the capacitance of the connecting cable between the AVR power rectifier bridge DC bus and the exciter to ground), that is, C=C4+C5; a is a proportional coefficient (used to distinguish the position of the excitation winding grounding point), the value range is 0~1.

[0098] When resonance occurs, the equivalent ground capacitance is C, and the equivalent circuit diagram can be further simplified as Figure 8 , wherein C=1 / (Zg+(1 / C5) / / (1 / C4)). Zg represents the impedance of the excitation winding grounding point, which is very complex, and in practice it is considered to be directly grounded, that is, Zg=0.

[0099] By calculating the equivalent impedance Zin as viewed from the three-phase thyristor rectifier bridge, the equivalent ground capacitance value at resonance can be obtained. The calculation process is as follows:

[0100]

[0101] If the influence of Rm is ignored, the equivalent impedance is:

[0102]

[0103] The following table is the equivalent input impedance Zin and the equivalent ground capacitance value C when the ground fault occurs at different positions at the resonance frequencies of 300 Hz and 600 Hz.

[0104]

[0105] From the above table, it can be seen that when the excitation winding of the exciter is grounded, the fault equivalent ground capacitance is the capacitance value shown in the table, and the circuit will resonate in series at different resonance frequencies.

[0106] From the ground capacitance formula in the above table, it can be seen that when a=1 / 2, the equivalent capacitance C reaches the minimum value. At this time, it can be deduced that when a=1 / 2, C is 2.25 uF.

[0107] Further, in order to obtain a preset harmonic, the simulation unit 100 further performs simulation analysis.

[0108] ​​Assuming the DC system is normal and the exciter is grounded, simulation analysis can yield the following waveform at the 300Hz resonant frequency (ground fault occurs at 6.5s): Figure 9 As shown.

[0109] Depend on Figure 9 It can be seen that during normal operation, the excitation current of the exciter is approximately 76A. After a ground fault occurs, the excitation current begins to oscillate, but its DC component remains essentially unchanged at approximately 76A. Simultaneously, it can be monitored that during normal operation, the DC negative bus voltage to ground is approximately -115V (e.g., ...). Figure 10 As shown in the figure, if the exciter does not experience a ground fault, there is no overvoltage in the system. When a ground fault occurs in the exciter, the DC negative bus voltage to ground begins to oscillate, and the peak value of the oscillation approaches 4000V (as shown in the figure). Figure 11 As shown), such a high voltage can burn out the insulation monitoring instrument's ground balance resistor. Similarly, it can be observed that when a ground fault occurs in the exciter, the voltage between the positive terminal of the excitation winding and ground also begins to oscillate, with the peak value approaching 4000V (as shown). Figure 12 (As shown).

[0110] Furthermore, in this embodiment of the invention, the resonance condition can be further simulated and analyzed, that is, the operating condition where the exciter is not grounded and the DC system experiences a grounding fault can be analyzed.

[0111] As mentioned above, when the system resonates at 300Hz, the overvoltage amplitude is high enough to damage insulation testers and other related equipment. Therefore, it is only necessary to simulate and analyze whether there is overvoltage under the condition that the exciter is not grounded and the LAB system is grounded at 300Hz.

[0112] like Figure 13 As shown, during normal operation, after a ground fault occurs in the DC system for 6.5 seconds, the exciter excitation current is approximately 76A. During normal operation, and after a ground fault occurs at the positive terminal of the DC system battery bank (or the DC system positive bus) for 6.5 seconds, the potential of the exciter excitation winding positive terminal to ground changes from 180V to 80V (e.g., ...). Figure 14 As shown), the negative electrode's potential to ground changes from -115V to -230V (as shown). Figure 15 (As shown in the figure). Therefore, it can be determined that a ground fault in a DC system will not lead to overvoltage.

[0113] The simulation analysis can determine that when the excitation system has a ground fault, series resonance occurs, and the resonance component of the excitation current at 300Hz causes overvoltage. Therefore, the preset harmonic can be obtained through the simulation analysis. Therefore, in the embodiment of the application, the excitation current of the excitation circuit is monitored in real time, and the harmonic component of the excitation current is obtained by analyzing the excitation current, and the harmonic component is compared with the preset harmonic component. If the harmonic component reaches the preset harmonic component, it is judged that the excitation machine has a ground fault or the DC system has a ground fault. At this time, the positive pole-to-ground voltage of the excitation winding of the excitation machine or the negative pole-to-ground voltage of the excitation winding of the excitation machine is synchronously obtained. If the positive pole-to-ground voltage of the excitation winding of the excitation machine or the negative pole-to-ground voltage of the excitation winding of the excitation machine reaches 1000V, an excitation winding ground fault alarm is output. If the positive pole-to-ground voltage of the excitation winding of the excitation machine or the negative pole-to-ground voltage of the excitation winding of the excitation machine reaches 1500V, an excitation winding ground fault alarm is output, and the auxiliary forced excitation circuit is controlled to be disconnected.

[0114] Further, in the embodiment of the application, the excitation machine system fault and the fault cause can be accurately and quickly determined through the simulation analysis. Based on this, the application also provides a corresponding improvement method. The specific improvement method can include: exiting the auxiliary forced excitation circuit and / or strengthening the insulation treatment of the excitation machine magnetic pole.

[0115] Specifically, exiting the auxiliary forced excitation circuit means disconnecting the auxiliary circuit (specifically, disconnecting the DC switch (LAB312JA) and the interval switch (GEX205JA) in the auxiliary circuit). Figure 2 The circuit diagram after the auxiliary circuit is disconnected is shown in Figure 16 When the excitation machine has a ground fault, the excitation voltage or the excitation current of the excitation machine will have a small fluctuation phenomenon because the resonance condition is destroyed, but there is no resonance overvoltage phenomenon.

[0116] It should be noted that after the auxiliary forced excitation circuit is exited, the automatic voltage regulator and the three-phase silicon controlled rectifier bridge DC side excitation system have a ground capacitance: C6=system loop equivalent ground capacitance (2.25 uF)-DC system ground capacitance (1.1uF)=1.15uF.

[0117] Simulation analysis is performed after the auxiliary forced excitation circuit is disconnected. When it is at a frequency of 300Hz (the excitation machine has a ground fault at 6.5s), the simulation waveform is shown in Figure 17 The excitation current amplification diagram of the excitation machine at time t=6~8s is shown in Figure 18 Figure 17 Figure 18 ​​It can be seen that after the auxiliary strong excitation circuit is disconnected, the excitation current of the exciter is about 76A when the exciter is normally operated, and although there is a small fluctuation, no oscillation phenomenon occurs when the excitation winding of the exciter is grounded for 6.5s.

[0118] As shown in Figure 19 and Figure 20 After the exciter is normally operated and the excitation winding of the exciter is grounded for 6.5s, the positive and negative ground voltage of the excitation winding of the exciter has a small change, but no large amplitude overvoltage phenomenon occurs. Therefore, when it is detected that it is in a resonant state, if it is detected that the excitation winding is grounded, the auxiliary strong excitation circuit can be disconnected, so as to avoid overvoltage damage to the equipment.

[0119] In the embodiment of the application, in order to improve the insulation level of the magnetic pole of the exciter and enhance the anti-breakdown capability of the magnetic pole, the insulation strength at the position of the magnetic pole coil pad can be strengthened to improve the ability of the magnetic pole coil to withstand the ground voltage. For example, the contact part of the magnetic pole coil and the pad can be reinforced by an insulating material.

[0120] Preferably, in the embodiment of the application, the pad can be integrally wrapped with a 0.14mm epoxy cotton glass powder mica tape.

[0121] In the embodiment of the application, after the contact part of the magnetic pole coil and the pad is reinforced, from the process and the effect after assembly, during the manufacturing process of the test magnetic pole, the mica tape wrapping pad is easy to operate, and the appearance of the mica tape molding area is neat and the size is good after wrapping. Therefore, the process of the scheme meets the product manufacturing requirements. From the electrical performance, it can be known from the analysis of the accessory test data that after the surface of the magnetic pole coil is treated according to the reinforcement scheme, the related requirements of the brushless exciter magnetic pole electrical test can be met, and the overall insulation performance is significantly enhanced. The specific comparison is as follows:

[0122]

[0123] From the above comparison, it can be known that the insulation reinforcement method of the embodiment of the application is good in operability and process, and solves the problem of relatively weak insulation at the pad of the magnetic pole, improves the overall insulation performance of the magnetic pole of the exciter, and reduces the probability of insulation breakdown core grounding fault under subsequent various working conditions.

[0124] The application analyzes the mechanism of the excitation system fault, establishes a large nuclear power unit excitation system simulation platform based on MATLAB / Simulink software without affecting the stable operation of the unit and changing the structure of the unit, can systematically and comprehensively reflect the electromagnetic transient performance of the internal fault of the generator and the excitation system thereof, reproduce the change law of the electrical quantity during the equipment fault of the excitation system, and demonstrate the mechanism of the common-mode resonance overvoltage caused by the common ground of the main loop of the excitation system and the DC system.

[0125] Further, the present application also provides a storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the method disclosed by the embodiments of the present application.

[0126] Further, the present application also provides an electronic device, comprising at least one processor, and a memory connected with the at least one processor;

[0127] The memory stores instructions executable by the at least one processor, and the instructions are configured to execute the method disclosed by the embodiments of the present application.

[0128] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts of each embodiment can be referred to each other. For the device disclosed by the embodiments, since it corresponds to the method disclosed by the embodiments, the description is relatively simple, and the related parts can be referred to the method part.

[0129] The skilled person can further realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized by electronic hardware, computer software or combination of the two. In order to clearly show the interchangeability of hardware and software, the components and steps of each example have been described in general in the above description. Whether the functions are realized by hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0130] The steps of the method or algorithm described in combination with the embodiments disclosed herein can be directly implemented by hardware, software module executed by a processor, or combination of the two. The software module can be placed in random access memory (RAM), memory, read only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, register, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0131] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it accordingly, and cannot limit the protection scope of the present application. Any equivalent changes and modifications made within the scope of the claims of the present application shall be included in the scope of the claims of the present application.

Claims

1. A field machine resonance overvoltage fault analysis system, characterized by, include: An excitation current acquisition unit is used to acquire the excitation current of the excitation circuit, wherein the excitation circuit includes: a generator, an excitation transformer, an automatic voltage regulator, a thyristor rectifier bridge, and an exciter pole winding; The excitation current analysis unit is used to analyze the excitation current and obtain the harmonic components of the excitation current. The simulation unit is used to perform simulation analysis on the excitation system to obtain the preset harmonics; The simulation unit includes: The modeling parameter acquisition module is used to acquire the modeling parameters of the excitation circuit; The modeling module is used to establish an excitation simulation model based on the modeling parameters; The ground fault analysis module is used to simulate the normal operation of the excitation system and various ground fault states based on the excitation simulation model, so as to obtain the harmonic characteristic frequency and resonant voltage value of the excitation current corresponding to the normal operation and various fault states of the excitation system. The resonance analysis module is used to perform resonance overvoltage fault analysis on the excitation system based on the harmonic characteristic frequency and resonance voltage value, so as to obtain the preset harmonic; The fault analysis unit is used to compare the harmonic components with the preset harmonics and analyze the exciter faults based on the comparison results.

2. The field machine resonant overvoltage fault analysis system of claim 1, wherein, The modeling parameters include: excitation circuit information, auxiliary circuit information, and DC insulation tester information.

3. A method of field machine resonance overvoltage fault analysis, characterized by, Includes the following steps: The excitation system is simulated and analyzed to obtain the preset harmonics; Obtain the excitation current of the excitation circuit, wherein the excitation circuit includes: a generator, an excitation transformer, an automatic voltage regulator, a thyristor rectifier bridge, and an exciter pole winding; The excitation current is analyzed to obtain its harmonic components; The harmonic components are compared with preset harmonics, and the exciter faults are analyzed based on the comparison results. The simulation analysis of the excitation system to obtain the preset harmonics includes: Collect the modeling parameters of the excitation circuit; An excitation simulation model is established based on the modeling parameters; Based on the excitation simulation model, the normal operation of the excitation system and various grounding fault states are simulated to obtain the harmonic characteristic frequency and resonant voltage value of the excitation current corresponding to the normal operation and various fault states of the excitation system. Based on the harmonic characteristic frequency and resonant voltage value, the excitation system is subjected to resonant overvoltage fault analysis to obtain the preset harmonic.

4. The field machine resonant overvoltage fault analysis method according to claim 3, characterized by, The modeling parameters include: excitation circuit information, auxiliary circuit information, and DC insulation tester information.

5. A storage medium having stored thereon a computer program, characterized in that When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 3-4.

6. An electronic device, comprising: It includes at least one processor; and a memory communicatively connected to said at least one processor; The memory stores instructions executable by the at least one processor, the instructions being configured to perform the method described in any one of claims 3-4.

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