Generator outlet side PT insulation state evaluation method and system

Abstract

The invention provides a generator outlet side PT insulation state evaluation method and system, and belongs to the field of electrical equipment state evaluation. The method comprises the following steps: simulating a normal operation state and a turn-to-turn short circuit state of the generator outlet side PT based on a simulation model of the generator outlet side PT; a primary side current monitoring device based on a generator outlet side PT monitors a primary side current of the generator outlet side PT in a running process in real time to obtain an actual PT primary side current; when the actual increase value of the primary side current of the PT reaches a preset value-added range, off-line detection is carried out on the PT on the outlet side of the generator; performing temperature monitoring on the PT at the outlet side of the generator; and based on the simulation result, the actual PT primary side current, the offline detection result and the temperature monitoring result, obtaining a generator outlet side PT insulation state determination result. And the purposes of discovering the PT insulation fault as early as possible and carrying out fault judgment and diagnosis by combining online monitoring and offline detection means for the PT are achieved.

Description

Technical Field

[0001] The present invention relates to the field of electrical equipment status assessment, and in particular to a generator outlet side PT insulation status assessment method, a generator outlet side PT insulation status assessment system, a machine-readable storage medium and an electronic device. Background Art

[0002] The PT on the generator outlet side is an electromagnetic voltage transformer, which converts the high voltage on the generator outlet side into a low voltage on the secondary side for measurement by measuring instruments to evaluate and monitor the operating status of the generator. It is not only beneficial to improve the economic benefits of the power plant, but also can effectively monitor abnormal conditions. It is one of the indispensable electrical equipment in the power plant. In recent years, power generation companies have experienced many non-stop events caused by short circuits between turns of the PT winding on the outlet side. Therefore, the insulation state of the PT on the generator outlet side is of great significance to the safe operation of the system. At present, for the slight short circuit between turns of the winding of the PT on the generator outlet side, the protection locking logic of the existing operating relay protection device is not perfect, and the equipment failure cannot be effectively identified in the early stage of the fault. It can only work when the fault occurs to the serious short circuit stage.

[0003] Therefore, how to timely detect the PT insulation fault on the generator outlet side and perform fault identification and diagnosis is a problem that needs to be solved urgently. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a method and system for evaluating the PT insulation status at the generator outlet side, so as to at least solve the above-mentioned problem of how to timely detect the PT insulation fault at the generator outlet side and perform fault identification and diagnosis.

[0005] In order to achieve the above object, the present invention provides a method for evaluating the insulation status of a PT at an outlet side of a generator, comprising:

[0006] Based on the simulation model of the PT at the generator outlet side, the normal operation state and the turn-to-turn short circuit state of the PT at the generator outlet side are simulated to obtain simulation results; wherein the simulation model of the PT at the generator outlet side is constructed based on the original data of the PT at the generator outlet side;

[0007] Based on the pre-built primary-side current monitoring device of the generator outlet side PT, the primary-side current of the generator outlet side PT during operation is monitored in real time to obtain the actual PT primary-side current;

[0008] When the increase value of the actual PT primary side current within the preset time period reaches the preset value-added range, the generator outlet side PT is tested offline to obtain the offline test result;

[0009] Monitor the temperature of the PT at the generator outlet side and obtain the temperature monitoring results;

[0010] Based on the simulation results, the actual PT primary side current, the offline detection results and the temperature monitoring results, the PT insulation state at the generator outlet side is determined, and the PT insulation state determination result at the generator outlet side is obtained.

[0011] Optionally, the establishment rules of the simulation model of the generator outlet side PT include:

[0012] Perform three-dimensional modeling based on the original data of the PT at the generator outlet side to obtain a 3D model corresponding to the PT at the generator outlet side;

[0013] Based on the 3D model corresponding to the PT on the generator outlet side, solver settings, excitation addition, solution domain addition, mesh generation, external circuit settings and solution settings are performed in sequence to obtain a simulation model of the PT on the generator outlet side;

[0014] The simulation model of the PT at the generator outlet side includes a PT model in normal operation and a PT model with turn-to-turn short-circuit defects.

[0015] Optionally, the above simulation results include a primary side simulation current and a simulation excitation characteristic curve when the generator outlet side PT is in normal operation;

[0016] After simulating the normal operating state of the PT at the generator outlet side, the method further includes:

[0017] The capacity calculation model of the voltage transformer is used to calculate the primary current value when the PT at the generator outlet is in no-load state;

[0018] Based on the primary side simulation current and the primary side current value when the generator outlet side PT is in no-load state, the correctness of the simulation model of the generator outlet side PT is verified to obtain the verification result;

[0019] The capacity calculation model is:

[0020]

[0021] I1 is the primary current of the voltage transformer, S N is the voltage transformer capacity, and U1 is the primary voltage of the voltage transformer.

[0022] Optionally, the simulation model of the PT on the generator outlet side includes a turn-to-turn short-circuit defect PT model, the turn-to-turn short-circuit defect PT model includes multiple turn-to-turn short-circuit defect PT sub-models, each turn-to-turn short-circuit defect PT sub-model is used to simulate the turn-to-turn short-circuit state of a defective PT with different short-circuit turns ratios, and the simulation results include a fitting curve of the relationship between the primary side current and the short-circuit turns ratio and a primary side current warning value when a preset turn-to-turn short circuit occurs in the generator outlet side PT;

[0023] Based on the simulation model of the PT at the generator outlet side, the turn-to-turn short circuit state of the PT at the generator outlet side is simulated, and the simulation results are obtained, including:

[0024] Based on each turn-to-turn short-circuit defect PT sub-model, the primary side current simulation value of the defective PT with different short-circuit turns ratios is simulated and calculated;

[0025] Based on the primary side current simulation value of the defective PT with each short-circuit turns ratio, the relationship data between the primary side current and the short-circuit turns ratio is determined, and a fitting curve between the primary side current and the short-circuit turns ratio is drawn;

[0026] Based on the primary side current simulation value of the defective PT with each short-circuit turns ratio, the primary side current warning value when a preset inter-turn short circuit occurs in the PT at the generator outlet side is determined.

[0027] Optionally, the above-mentioned offline detection results include a primary side excitation characteristic curve of the generator outlet side PT, a secondary side excitation characteristic curve and a partial discharge amount of the generator outlet side PT at rated voltage;

[0028] The above-mentioned offline detection of the PT at the generator outlet side obtains offline detection results, including:

[0029] Conduct an excitation characteristic test on the PT at the generator outlet side to obtain the primary side excitation characteristic curve and the secondary side excitation characteristic curve of the PT at the generator outlet side;

[0030] A pulse current partial discharge test is carried out on the PT at the generator outlet side to obtain the partial discharge amount of the PT at the generator outlet side under the rated voltage.

[0031] Optionally, the above simulation results include the primary side simulation current when the generator outlet side PT is in normal operation, the simulation excitation characteristic curve, the relationship fitting curve between the primary side current and the short-circuit turns ratio, and the primary side current warning value when a preset inter-turn short circuit occurs in the generator outlet side PT;

[0032] The above-mentioned method is based on the simulation results, the actual PT primary side current, the offline detection results and the temperature monitoring results to determine the insulation status of the generator outlet side PT, including:

[0033] The insulation status of the PT at the generator outlet is evaluated online based on the actual PT primary current, the simulated primary current of the PT at the generator outlet in normal operation, the fitting curve of the relationship between the primary current and the short-circuit turns ratio, the primary current warning value when the preset inter-turn short circuit occurs at the generator outlet PT, and the temperature monitoring results;

[0034] When the online evaluation result shows that the generator outlet side PT is an abnormal PT, the generator outlet side PT insulation state is determined based on the simulated excitation characteristic curve and the offline detection result.

[0035] Optionally, the above-mentioned online evaluation of the PT insulation status at the generator outlet side includes:

[0036] When the increase value of the actual PT primary side current within the preset time period does not reach the preset value-added range, the insulation state of the PT at the generator outlet side is judged to be a turn-to-turn short-circuit state according to the actual PT primary side current, the primary side simulation current of the PT at the generator outlet side in normal operation, the relationship fitting curve between the primary side current and the short-circuit turns ratio, and the primary side current warning value when the preset turn-to-turn short-circuit occurs at the PT at the generator outlet side;

[0037] If it is determined that the insulation state of the PT on the generator outlet side is not a turn-to-turn short-circuit state and the temperature monitoring result shows that the temperature of the PT on the generator outlet side is lower than the preset temperature threshold, the online evaluation result is determined to be that the PT on the generator outlet side is a normal PT; otherwise, the online evaluation result is determined to be that the PT on the generator outlet side is an abnormal PT.

[0038] Optionally, the above-mentioned offline detection result includes a primary side excitation characteristic curve of the PT at the generator outlet side and a partial discharge amount of the PT at the generator outlet side at rated voltage;

[0039] The above-mentioned method of determining the insulation status of the PT at the generator outlet side based on the simulated excitation characteristic curve and the offline detection result includes:

[0040] If the primary side excitation characteristic curve of the PT on the generator outlet side is inconsistent with the simulated excitation characteristic curve and / or the partial discharge of the PT on the generator outlet side at the rated voltage is greater than the preset partial discharge threshold, the insulation state of the PT on the generator outlet side is determined to be an abnormal PT insulation state.

[0041] A second aspect of the present invention provides a generator outlet side PT insulation status assessment system, comprising:

[0042] A simulation module is used to simulate the normal operation state and the turn-to-turn short circuit state of the PT at the generator outlet side based on the simulation model of the PT at the generator outlet side to obtain simulation results; wherein the simulation model of the PT at the generator outlet side is constructed based on the original data of the PT at the generator outlet side;

[0043] The primary side current monitoring module is used to monitor the primary side current of the generator outlet side PT in real time during operation based on the pre-built primary side current monitoring device of the generator outlet side PT to obtain the actual PT primary side current;

[0044] An offline detection module is used to perform offline detection on the generator outlet side PT when the increase value of the actual PT primary side current within a preset time period reaches a preset value-added range to obtain an offline detection result;

[0045] The temperature monitoring module is used to monitor the temperature of the PT at the generator outlet side and obtain the temperature monitoring results;

[0046] The determination module is used to determine the PT insulation state at the generator outlet side based on the simulation result, the actual PT primary side current, the offline detection result and the temperature monitoring result, and obtain the PT insulation state determination result at the generator outlet side.

[0047] In a third aspect of the present invention, a machine-readable storage medium is provided, on which instructions are stored. When the instructions are executed by a processor, the processor is configured to execute the above-mentioned method for evaluating the insulation status of the PT at the generator outlet side.

[0048] In a fourth aspect of the present invention, an electronic device is provided, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the generator outlet side PT insulation status assessment method is implemented.

[0049] Through the above technical scheme, a method and system for evaluating the insulation state of the PT at the generator outlet is provided. Based on the simulation model of the PT at the generator outlet, the normal operation state and the turn-to-turn short circuit state of the PT at the generator outlet are simulated respectively to obtain simulation results. A primary-side current monitoring device of the PT at the generator outlet is built, so that the primary-side current of the PT at the generator outlet during operation is monitored in real time through the primary-side current monitoring device of the PT at the generator outlet to obtain the actual PT primary-side current. When the increase value of the actual PT primary-side current within the preset time period reaches the preset value-added range, the PT at the generator outlet is offline detected to obtain the offline detection result, so that the insulation state of the PT in online operation is preliminarily evaluated and warned in time by real-time monitoring the change of the PT primary-side current, and the occurrence of faults is effectively prevented in advance. And the method and system comprehensively evaluate the insulation state of the PT based on the offline detection means when the PT is offline, which can effectively identify and diagnose the insulation fault of the PT. Then the temperature of the PT at the generator outlet is monitored to obtain the temperature monitoring result, and the insulation state of the PT at the generator outlet is judged in combination with the temperature monitoring result, which can further improve the reliability of the judgment result. Combined with the simulation results, the actual PT primary current, the offline detection results and the temperature monitoring results, the PT insulation state at the generator outlet is comprehensively determined to obtain the PT insulation state determination result at the generator outlet. The method and system comprehensively consider the PT operating environment at the generator outlet, monitor the PT state at the generator outlet in real time online and detect the PT insulation state offline, so as to evaluate the insulation state of the PT at the generator outlet by integrating online monitoring and offline detection when the actual PT is running, and realize the purpose of combining online monitoring and offline detection means for PT to detect PT insulation faults as early as possible and perform fault identification and diagnosis, which can improve the safety and reliability of unit operation.

[0050] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0052] Figure 1 It is a flow chart of a method for evaluating the insulation status of a PT at a generator outlet provided by an embodiment of the present invention;

[0053] Figure 2 It is an ANSYS Maxwell modeling flow chart provided by one embodiment of the present invention;

[0054] Figure 3It is a BH curve diagram of a B30G120 silicon steel sheet provided by an embodiment of the present invention;

[0055] Figure 4 is a schematic diagram of a normal PT three-dimensional model provided by one embodiment of the present invention;

[0056] Figure 5 is a schematic diagram of a normal PT external circuit model provided by an embodiment of the present invention;

[0057] Figure 6 is a schematic diagram of an abnormal PT three-dimensional model provided by an embodiment of the present invention;

[0058] Figure 7 It is a schematic diagram of an abnormal PT external circuit model provided by one embodiment of the present invention;

[0059] Figure 8 It is a schematic diagram of a fitting curve of the relationship between the short-circuit turns ratio and the primary-side current simulated by ANSYS, provided in one embodiment of the present invention;

[0060] Fig. 9 is a schematic diagram of a primary-side current monitoring device provided by an embodiment of the present invention;

[0061] Fig.10 It is a wiring diagram of a PT short circuit test simulation platform provided by one embodiment of the present invention;

[0062] Fig.11 It is a normal PT infrared temperature measurement spectrum provided by one embodiment of the present invention;

[0063] Fig.12 It is an abnormal PT infrared temperature measurement spectrum provided by one embodiment of the present invention;

[0064] Fig.13 It is a flow chart of an implementation method of a PT insulation status assessment method of an online monitoring and offline detection fusion algorithm provided by an embodiment of the present invention;

[0065] Fig.14 It is a block diagram of a generator outlet side PT insulation status evaluation system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0066] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0067] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0068] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0069] Example 1

[0070] Figure 1 FIG. 1 is a flow chart of a method for evaluating the insulation status of a PT at a generator outlet provided by an embodiment of the present invention. Figure 1 As shown, an embodiment of the present invention provides a method for evaluating the insulation status of a PT at a generator outlet, comprising:

[0071] S110: Based on the simulation model of the PT at the generator outlet side, the normal operation state and the turn-to-turn short circuit state of the PT at the generator outlet side are simulated to obtain simulation results; wherein the simulation model of the PT at the generator outlet side is constructed based on the original data of the PT at the generator outlet side;

[0072] Specifically, the normal operating state of the PT on the generator outlet side is simulated according to the simulation model of the PT on the generator outlet side, and characteristic quantities such as the amplitude, phase and core flux of the primary side current when the PT on the generator outlet side is operating normally are obtained, as well as the primary side simulation current and simulation excitation characteristic curve of the PT on the generator outlet side when it is in normal operating state.

[0073] In some implementations of the present embodiment, the simulation model of the above-mentioned generator outlet side PT includes a turn-to-turn short-circuit defect PT model, the turn-to-turn short-circuit defect PT model includes multiple turn-to-turn short-circuit defect PT sub-models, each turn-to-turn short-circuit defect PT sub-model is used to simulate the turn-to-turn short-circuit state of defective PTs with different short-circuit turn ratios, and the simulation results include a fitting curve of the relationship between the primary side current and the short-circuit turn ratio and a primary side current warning value when a preset turn-to-turn short circuit occurs in the generator outlet side PT; based on the simulation model of the generator outlet side PT, the turn-to-turn short circuit state of the generator outlet side PT is simulated to obtain simulation results, including: based on each turn-to-turn short-circuit defect PT sub-model, simulating and calculating the primary side current simulation value of the defective PT with different short-circuit turn ratios; based on the primary side current simulation value of the defective PT with each short-circuit turn ratio, determining the relationship data between the primary side current and the short-circuit turn ratio, and drawing the relationship fitting curve between the primary side current and the short-circuit turn ratio; based on the primary side current simulation value of the defective PT with each short-circuit turn ratio, determining the primary side current warning value when a preset turn-to-turn short circuit occurs in the generator outlet side PT.

[0074] Specifically, an equivalent circuit diagram of a turn-to-turn short circuit is designed for the PT at the generator outlet side, and the ratio of the short-circuit turns to the total turns is set to simulate defective PTs with different short-circuit turn ratios (it should be noted that the primary coil of the defective PT can be divided into three coils, the middle coil represents the short-circuit turns, and the turns of each coil will be confirmed by the short-circuit turn ratio calculation, so that the short-circuit situation between the coil turns can be simulated). Then, ANSYS Maxwell is used to model and simulate each turn-to-turn short circuit defective PT sub-model, and the relationship between the short-circuit turn ratio and the primary current when the turn-to-turn short circuit occurs is obtained, and the relationship fitting curve is drawn, and the primary current warning value when the PT has a 0.05% turn-to-turn short circuit is obtained. Exemplarily, the defective PTs with short-circuit turn ratios of 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% are simulated, and the primary current simulation values ​​of each defective PT are simulated and calculated to obtain the relationship between the primary current and the short-circuit turn ratio, and the relationship fitting curve is drawn.

[0075] S120: Based on the pre-built primary side current monitoring device of the generator outlet side PT, the primary side current of the generator outlet side PT during operation is monitored in real time to obtain the actual PT primary side current;

[0076] Specifically, a primary current monitoring device and wiring diagram of the PT on the generator outlet side are designed, so that the primary current of the PT on the generator outlet side during the specific operation process is monitored in real time through the primary current monitoring device of the PT on the generator outlet side. Since the primary current of the PT is at the milliampere level and the primary voltage is very high, a PT primary current monitoring device that can accurately monitor the primary current in real time is designed. The specific steps are as follows: A. Prepare a current transformer with N secondary turns, and pass the PT primary grounding wire through the current transformer with 1 turn. At this time, the primary current of the current transformer is I1 and the secondary current is I2; B. Connect a high-precision resistor with a resistance of R to the secondary side of the current transformer to convert the current signal I2 into a voltage signal U; C. Use the acquisition card device to collect the voltage signal U at both ends of the high-precision resistor and transmit it to the host; D. Monitor the voltage signal in real time in the host, and convert it into the primary current through the background import formula to calculate the value of the primary current. The calculation formula is as follows: E. Assemble the above components into an integrated device to obtain the PT primary current monitoring device. The schematic diagram of the primary current monitoring device is as follows: Fig. 9 As shown, Fig. 9 It is a principle diagram of a primary-side current monitoring device provided by an embodiment of the present invention. The primary-side current monitoring device is installed on the primary-side grounding wire of the PT.

[0077] S130: When the increase value of the actual PT primary side current within the preset time period reaches the preset value-added range, an offline detection is performed on the generator outlet side PT to obtain an offline detection result;

[0078] Specifically, when the actual PT primary current increases by five times or more, the PT at the generator outlet side is tested offline. This method monitors the changes in the PT primary current in real time, conducts preliminary evaluation and early warning of the PT insulation status in online operation, and effectively prevents the occurrence of faults in advance. Compared with the method of monitoring the secondary current, it is more sensitive. In actual operation, the insulation status of the PT at the generator outlet side is evaluated by integrating online monitoring and offline detection.

[0079] In some implementations of the present embodiment, the above-mentioned offline detection results include the primary-side excitation characteristic curve, the secondary-side excitation characteristic curve and the partial discharge amount of the PT on the generator outlet side at the rated voltage; the above-mentioned offline detection of the PT on the generator outlet side to obtain the offline detection results includes: performing an excitation characteristic test on the PT on the generator outlet side to obtain the primary-side excitation characteristic curve and the secondary-side excitation characteristic curve of the PT on the generator outlet side; performing a pulse current partial discharge test on the PT on the generator outlet side to obtain the partial discharge amount of the PT on the generator outlet side at the rated voltage.

[0080] Specifically, the PT detected as abnormal by the online monitoring means (the online monitoring means is the process of obtaining the actual PT primary-side current in S120) is powered off and prepared for offline detection; an excitation characteristic test is performed on the tested PT (i.e. the abnormal PT detected) to obtain the primary-side excitation characteristic curve and the secondary-side excitation characteristic curve of the PT on the generator outlet side; a pulse current partial discharge test is performed on the tested PT to obtain the partial discharge amount of the PT at the rated voltage.

[0081] S140: Monitor the temperature of the PT at the generator outlet side and obtain the temperature monitoring result;

[0082] Specifically, an infrared thermometer is used to monitor the temperature of the PT at the generator outlet side (the PT at the generator outlet side can be a normal PT or an abnormal PT), and the PT shell temperature is recorded after working at the rated voltage for five minutes. Temperature monitoring of the PT at the generator outlet side can be used as a double monitoring method for monitoring the PT insulation status, further improving the reliability of judging the insulation status of the PT at the generator outlet side.

[0083] S150: Based on the simulation results, the actual PT primary side current, the offline detection results and the temperature monitoring results, the PT insulation state at the generator outlet side is determined to obtain the PT insulation state determination result at the generator outlet side.

[0084] Specifically, the method simulates the normal operation state and the turn-to-turn short circuit state of the PT at the generator outlet side based on the simulation model of the PT at the generator outlet side, and obtains the simulation results. A primary-side current monitoring device of the PT at the generator outlet side is built, so that the primary-side current of the PT at the generator outlet side during operation is monitored in real time through the primary-side current monitoring device of the PT at the generator outlet side, and the actual PT primary-side current is obtained. When the increase value of the actual PT primary-side current within the preset time period reaches the preset value-added range, the PT at the generator outlet side is offline detected to obtain the offline detection result, so that the insulation state of the PT in online operation is preliminarily evaluated and warned in time by real-time monitoring of the change of the PT primary-side current, and the occurrence of faults is effectively prevented in advance. And the method comprehensively evaluates the insulation state of the PT based on the offline detection means when the PT is offline, and can effectively identify and diagnose the insulation fault of the PT. Then the temperature of the PT at the generator outlet side is monitored to obtain the temperature monitoring result, and the insulation state of the PT at the generator outlet side is judged in combination with the temperature monitoring result, which can further improve the reliability of the judgment result. Combined with the simulation results, the actual PT primary current, the offline detection results and the temperature monitoring results, the PT insulation state of the generator outlet side is comprehensively determined to obtain the PT insulation state determination result of the generator outlet side. This method comprehensively considers the PT operating environment on the generator outlet side, monitors the PT state on the generator outlet side in real time online and detects the PT insulation state offline, so as to comprehensively evaluate the insulation state of the PT on the generator outlet side by integrating online monitoring and offline detection when the actual PT is running, and realizes the purpose of combining online monitoring and offline detection means for PT to detect PT insulation faults as early as possible and perform fault identification and diagnosis, which can improve the safety and reliability of unit operation.

[0085] In some implementations of this embodiment, after evaluating the PT insulation status on the generator outlet side by combining online monitoring and offline detection fusion means, the method further includes: obtaining an evaluation report based on the determination result of the PT insulation status on the generator outlet side.

[0086] Please refer to Figure 2 , Figure 2 It is an ANSYS Maxwell modeling flow chart provided by an embodiment of the present invention. In some embodiments of this embodiment, the establishment rules of the simulation model of the PT on the outlet side of the generator include: performing three-dimensional modeling based on the original data of the PT on the outlet side of the generator to obtain a 3D model corresponding to the PT on the outlet side of the generator; based on the 3D model corresponding to the PT on the outlet side of the generator, performing solver setting, excitation addition, solution domain addition, meshing, external circuit setting and solution setting in sequence to obtain a simulation model of the PT on the outlet side of the generator; wherein the simulation model of the PT on the outlet side of the generator includes a PT model of a normal operating state and a PT model of a turn-to-turn short-circuit defect.

[0087] Specifically, according to the specific operating environment of the generator outlet side PT and the data provided by the manufacturer, the original data of the generator outlet side PT is obtained. The simulation model of the generator outlet side PT is established based on ANSYS Maxwell simulation software, and the simulation model in ANSYS Maxwell simulation software includes Maxwell 3D model and circuit external circuit model.

[0088] Among them, the original data of the PT on the generator outlet side includes the PT rated transformation ratio, the number of turns of the primary winding and the secondary winding, the primary rated voltage, the primary winding DC resistance and the secondary winding DC resistance, etc.

[0089] In some implementations of this embodiment, the above-mentioned simulation results include the primary side simulation current and the simulation excitation characteristic curve when the generator outlet side PT is in normal operating state; after simulating the normal operating state of the generator outlet side PT, the method further includes: using the capacity calculation model of the voltage transformer to calculate the primary side current value when the generator outlet side PT is in no-load state; based on the primary side simulation current and the primary side current value when the generator outlet side PT is in no-load state, the correctness of the simulation model of the generator outlet side PT is verified to obtain a verification result; wherein the capacity calculation model is: is the primary current of the voltage transformer, S N is the voltage transformer capacity, and U1 is the primary voltage of the voltage transformer.

[0090] Specifically, the primary current and excitation characteristic curve of the generator outlet side PT in normal operation are obtained based on ANSYS Maxwell simulation and recorded. The primary current value of the generator outlet side PT when it is no-load is calculated using the capacity of the voltage transformer, so as to compare the primary side simulation current with the primary side current value of the generator outlet side PT when it is no-load, and verify the correctness of the simulation model of the generator outlet side PT.

[0091] Among them, the simulated excitation characteristic curve of the generator outlet side PT in normal operation obtained by the PT simulation model has guiding significance for the evaluation standard of the excitation characteristic test in the offline detection means.

[0092] Please refer to Fig.13 , Fig.13It is a flow chart of the implementation of a PT insulation state assessment method of an online monitoring and offline detection fusion algorithm provided by an embodiment of the present invention. In some implementations of this embodiment, the above simulation results include the primary side simulation current of the generator outlet side PT in normal operation, the simulation excitation characteristic curve, the relationship fitting curve between the primary side current and the short-circuit turns ratio, and the primary side current warning value when a preset inter-turn short circuit occurs in the generator outlet side PT; the above determination of the generator outlet side PT insulation state based on the simulation results, the actual PT primary side current, the offline detection results and the temperature monitoring results includes:

[0093] The insulation status of the PT at the generator outlet is evaluated online based on the actual PT primary current, the simulated primary current of the PT at the generator outlet in normal operation, the fitting curve of the relationship between the primary current and the short-circuit turns ratio, the primary current warning value when the preset inter-turn short circuit occurs at the generator outlet PT, and the temperature monitoring results;

[0094] Specifically, the above-mentioned online evaluation of the insulation state of the PT at the generator outlet side includes: when the increase value of the actual PT primary side current within the preset time period does not reach the preset value-added range, according to the actual PT primary side current, the primary side simulation current of the generator outlet side PT in normal operation, the relationship fitting curve between the primary side current and the short-circuit turns ratio, and the primary side current warning value when the generator outlet side PT has a preset turn-to-turn short circuit, it is determined whether the insulation state of the generator outlet side PT belongs to the turn-to-turn short circuit state; if it is determined that the insulation state of the generator outlet side PT does not belong to the turn-to-turn short circuit state and the temperature monitoring result shows that the temperature of the generator outlet side PT is lower than the preset temperature threshold, then the online evaluation result is determined to be that the generator outlet side PT is a normal PT, otherwise it is determined to be that the generator outlet side PT is an abnormal PT. Thus, by comparing the actual PT primary side current monitored in real time with the primary side simulation current, combined with the relationship fitting curve and the primary side current warning value and the temperature monitoring result contained in the simulation result, the health state of the generator outlet side PT can be preliminarily evaluated online.

[0095] When the online evaluation result shows that the generator outlet side PT is an abnormal PT, the generator outlet side PT insulation state is determined based on the simulated excitation characteristic curve and the offline detection result.

[0096] In some implementations of this embodiment, the above-mentioned offline detection result includes the primary side excitation characteristic curve of the generator outlet side PT and the partial discharge amount of the generator outlet side PT at the rated voltage; the above-mentioned determination of the generator outlet side PT insulation state based on the simulated excitation characteristic curve and the offline detection result includes: if the primary side excitation characteristic curve of the generator outlet side PT is inconsistent with the simulated excitation characteristic curve and / or the partial discharge amount of the generator outlet side PT at the rated voltage is greater than the preset partial discharge amount threshold, then the generator outlet side PT insulation state is determined to be an abnormal PT insulation state. Thus, the excitation characteristic test and the partial discharge test are combined to determine whether the generator outlet side PT can continue to operate normally.

[0097] Exemplarily, the preset partial discharge threshold may be 50 pc.

[0098] Example 2

[0099] This embodiment discloses a PT insulation status assessment method that integrates an online monitoring and offline detection algorithm, which is described using the following embodiment.

[0100] A group of generator outlet side PTs of power plant A are selected, model JDZX0-20G, and the specific parameters of JDZX0-20G are shown in Table 1:

[0101] Table 1 Specific parameters of JDZX0-20G

[0102] Nameplate parameters Rating <![CDATA[Capacity S N / Frequency]]> 30VA / 50Hz Primary / secondary rated voltage 20KV / 100V Core size 300mm×205mm×60mm High and low voltage winding turns 23960 / 120 Transformation ratio 20 / 0.1 High and low voltage winding internal resistance / Ω 7000 / 0.317

[0103] (1) Based on the above parameters and the PT core BH curve provided by the manufacturer, the PT is modeled in the ANSYS electrical desktop software. The modeling includes a normal PT and a PT model with a turn-to-turn short circuit defect. The modeling flow chart is as follows: Figure 2 .

[0104] Due to the unique structure of the PT core, the primary coil and the secondary coil are wound on the iron column on the same side, and the core is made of a whole cold-rolled oriented silicon steel sheet, which has the advantages of good magnetic conductivity and low hysteresis loss. Therefore, the core material selected in the modeling is Baosteel B30G120 high-quality silicon steel sheet, and its BH curve is as follows Figure 3 The coil material is set to copper wire.

[0105] The function of PT is to convert high voltage into low voltage, so the number of turns of the primary side coil is much higher than that of the secondary side coil. In the modeling of this embodiment, the number of turns of the primary side is set to 23960 turns, and the number of turns of the secondary side is 120 turns.

[0106] The primary coil of the abnormal PT can be divided into three coils. The middle coil represents the short-circuited turns. The turns of each coil will be confirmed by the short-circuit turns ratio calculation. Based on this step, the short-circuit situation between coil turns is simulated.

[0107] The PT three-dimensional model and external circuit model constructed in this embodiment are as follows Figure 4 , Figure 5 , Figure 6 and Figure 7 shown.

[0108] (2) Based on ANSYS Maxwell simulation, the PT primary current and excitation characteristic curves are obtained and recorded. The primary current value at no-load is calculated using the capacity of the voltage transformer. The calculation formula is:

[0109] Where I1 is the primary current of the voltage transformer, S N is the voltage transformer capacity, and U1 is the primary voltage of the voltage transformer. By comparing the calculation results with the simulation results, the correctness of the simulation is preliminarily verified.

[0110] (3) Simulate the defective PTs with short-circuit turns ratios of 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%, and calculate the primary current simulation value of the defective PT to obtain the relationship between the primary current and the short-circuit turns ratio. Then draw a fitting curve. The curve drawn in this example is as follows: Figure 8 shown.

[0111] (4) Design a PT primary current monitoring device. Since the PT primary current is at the milliampere level and the primary voltage is very high, a method and device that can accurately monitor the primary current in real time is designed. The specific steps are as follows:

[0112] A. Prepare a current transformer with N secondary turns. Pass the PT primary ground wire through the current transformer with 1 turn. At this time, the primary current of the current transformer is I1 and the secondary current is I2.

[0113] B. Connect a high-precision resistor with a resistance of R to the secondary side of the current transformer to convert the current signal I2 into a voltage signal U;

[0114] C. Use the acquisition card device to collect the voltage signal U across the high-precision resistor and transmit it to the host;

[0115] D. Monitor the voltage signal in real time in the host, and convert it into the primary current by importing the formula in the background, and calculate the value of the primary current. The calculation formula is as follows: The above components are assembled into an integrated device to obtain a PT primary current monitoring device. The principle diagram of the monitoring device is shown in the figure. Fig. 9 , the monitoring device is installed on the primary grounding wire of the PT.

[0116] (5) Build a PT short-circuit test simulation platform, measure the primary current of the PT and test the excitation characteristics, and compare them with the simulation results in (2) to further verify the correctness of the simulation model. Fig.10 shown.

[0117] (6) Conduct a partial discharge test on the PT in a simulation test platform, measure the normal partial discharge of the PT, and record it. In this embodiment, the normal partial discharge of the PT does not exceed 50 pc.

[0118] (7) An infrared thermometer is used to monitor the temperature of the normal PT and the abnormal PT, and the PT shell temperature is recorded after working for five minutes at the rated voltage. In this embodiment, the abnormal PT shell temperature rises to more than 40 degrees Celsius. The infrared temperature measurement graph is as follows: Fig.11 and Fig.12 shown.

[0119] (8) In actual operation, an online monitoring and offline detection fusion evaluation method is adopted. The specific flow chart of this evaluation method is as follows: Fig.13 The basis for judging each characteristic quantity in the figure is: when the primary current increases by five times or more, it is judged as yes, otherwise it is no; when the temperature rises to more than 40 degrees, it is judged as abnormal, otherwise it is normal; the excitation characteristic test and the partial discharge test are compared with the normal values ​​in (5) and (6) to judge.

[0120] (9) Based on the above method and the fitting curve of the PT primary current and the short-circuit turns ratio, the turn-to-turn short-circuit turns ratio of the PT is evaluated, and combined with the excitation characteristic test and partial discharge test, it is determined whether the PT can continue to operate normally.

[0121] Example 3

[0122] Fig.14 1 is a block diagram of a generator outlet side PT insulation status evaluation system provided by an embodiment of the present invention. Fig.14 As shown, an embodiment of the present invention provides a generator outlet side PT insulation state assessment system, comprising:

[0123] A simulation module is used to simulate the normal operation state and the turn-to-turn short circuit state of the PT at the generator outlet side based on the simulation model of the PT at the generator outlet side to obtain simulation results; wherein the simulation model of the PT at the generator outlet side is constructed based on the original data of the PT at the generator outlet side;

[0124] The primary side current monitoring module is used to monitor the primary side current of the generator outlet side PT in real time during operation based on the pre-built primary side current monitoring device of the generator outlet side PT to obtain the actual PT primary side current;

[0125] An offline detection module is used to perform offline detection on the generator outlet side PT when the increase value of the actual PT primary side current within a preset time period reaches a preset value-added range to obtain an offline detection result;

[0126] The temperature monitoring module is used to monitor the temperature of the PT at the generator outlet side and obtain the temperature monitoring results;

[0127] The determination module is used to determine the PT insulation state at the generator outlet side based on the simulation result, the actual PT primary side current, the offline detection result and the temperature monitoring result, and obtain the PT insulation state determination result at the generator outlet side.

[0128] Specifically, the system simulates the normal operation state and the turn-to-turn short circuit state of the PT at the generator outlet side based on the simulation model of the PT at the generator outlet side, and obtains the simulation results. A primary-side current monitoring device of the PT at the generator outlet side is built, so that the primary-side current of the PT at the generator outlet side during operation is monitored in real time through the primary-side current monitoring device of the PT at the generator outlet side, and the actual PT primary-side current is obtained. When the increase value of the actual PT primary-side current within the preset time period reaches the preset value-added range, the PT at the generator outlet side is offline detected to obtain the offline detection result, so that the insulation state of the PT in online operation is preliminarily evaluated and warned in time by real-time monitoring of the change of the PT primary-side current, and the occurrence of faults is effectively prevented in advance. And the system comprehensively evaluates the insulation state of the PT based on the offline detection means when the PT is offline, and can effectively identify and diagnose the insulation fault of the PT. Then the temperature of the PT at the generator outlet side is monitored to obtain the temperature monitoring result, and the insulation state of the PT at the generator outlet side is judged in combination with the temperature monitoring result, which can further improve the reliability of the judgment result. Combined with the simulation results, the actual PT primary current, offline detection results and temperature monitoring results, the PT insulation state of the generator outlet side is comprehensively determined to obtain the PT insulation state determination result of the generator outlet side. The system comprehensively considers the PT operating environment on the generator outlet side, monitors the PT state on the generator outlet side in real time online and detects the PT insulation state offline, so as to evaluate the insulation state of the PT on the generator outlet side by integrating online monitoring and offline detection when the actual PT is running, and realizes the purpose of combining online monitoring and offline detection means for PT to detect PT insulation faults as early as possible and perform fault identification and diagnosis, which can improve the safety and reliability of unit operation.

[0129] The optional implementation modes of the embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical scheme of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0130] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0131] Those skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including several instructions for making a single-chip microcomputer, a chip or a processor (processor) execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0132] In addition, various implementation modes of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed by the embodiments of the present invention.

Claims

1. A method for evaluating the insulation status of a PT at a generator outlet, characterized in that: include: Based on the simulation model of the PT at the generator outlet side, the normal operation state and the turn-to-turn short circuit state of the PT at the generator outlet side are simulated to obtain simulation results; wherein the simulation model of the PT at the generator outlet side is constructed based on the original data of the PT at the generator outlet side; Based on the pre-built primary-side current monitoring device of the generator outlet side PT, the primary-side current of the generator outlet side PT during operation is monitored in real time to obtain the actual PT primary-side current; When the increase value of the actual PT primary side current within the preset time period reaches the preset value-added range, the generator outlet side PT is tested offline to obtain the offline test result; Monitor the temperature of the PT at the generator outlet side and obtain the temperature monitoring results; Based on the simulation results, the actual PT primary side current, the offline detection results and the temperature monitoring results, the PT insulation state at the generator outlet side is determined, and the PT insulation state determination result at the generator outlet side is obtained.

2. The method for evaluating the insulation status of the PT at the generator outlet side according to claim 1, characterized in that: The establishment rules of the simulation model of the generator outlet side PT include: Perform three-dimensional modeling based on the original data of the PT at the generator outlet side to obtain a 3D model corresponding to the PT at the generator outlet side; Based on the 3D model corresponding to the PT on the generator outlet side, solver settings, excitation addition, solution domain addition, mesh generation, external circuit settings and solution settings are performed in sequence to obtain a simulation model of the PT on the generator outlet side; The simulation model of the generator outlet side PT includes a normal operating PT model and a turn-to-turn short circuit defect PT model.

3. The method for evaluating the insulation status of the PT at the generator outlet side according to claim 1, characterized in that: The simulation results include the primary side simulation current and simulation excitation characteristic curve of the generator outlet side PT when the generator is in normal operation; After simulating the normal operating state of the PT at the generator outlet side, the method further includes: The capacity calculation model of the voltage transformer is used to calculate the primary current value when the PT at the generator outlet is in no-load state; The correctness of the simulation model of the generator outlet side PT is verified based on the primary side simulation current and the primary side current value when the generator outlet side PT is in no-load state, and the verification result is obtained; Wherein, the capacity calculation model is: I1 is the primary current of the voltage transformer, S N is the voltage transformer capacity, and U1 is the primary voltage of the voltage transformer.

4. The method for evaluating the PT insulation status at the generator outlet side according to claim 1, characterized in that: The simulation model of the generator outlet side PT includes a turn-to-turn short-circuit defect PT model, the turn-to-turn short-circuit defect PT model includes multiple turn-to-turn short-circuit defect PT sub-models, each turn-to-turn short-circuit defect PT sub-model is used to simulate the turn-to-turn short-circuit state of a defective PT with different short-circuit turns ratios, and the simulation result includes a fitting curve of the relationship between the primary side current and the short-circuit turns ratio and a primary side current warning value when a preset turn-to-turn short-circuit occurs in the generator outlet side PT; Based on the simulation model of the PT at the generator outlet side, the turn-to-turn short circuit state of the PT at the generator outlet side is simulated, and the simulation results are obtained, including: Based on each turn-to-turn short-circuit defect PT sub-model, the primary side current simulation value of the defective PT with different short-circuit turns ratios is simulated and calculated; Based on the primary side current simulation value of the defective PT with each short-circuit turns ratio, the relationship data between the primary side current and the short-circuit turns ratio is determined, and a fitting curve between the primary side current and the short-circuit turns ratio is drawn; Based on the primary side current simulation value of the defective PT with each short-circuit turns ratio, the primary side current warning value when a preset inter-turn short circuit occurs in the PT at the generator outlet side is determined.

5. The method for evaluating the insulation status of the PT at the generator outlet side according to claim 1, characterized in that: The offline detection result includes the primary side excitation characteristic curve of the generator outlet side PT, the secondary side excitation characteristic curve and the partial discharge amount of the generator outlet side PT at the rated voltage; The offline detection of the PT at the generator outlet side to obtain the offline detection result includes: Conduct an excitation characteristic test on the PT at the generator outlet side to obtain the primary side excitation characteristic curve and the secondary side excitation characteristic curve of the PT at the generator outlet side; A pulse current partial discharge test is carried out on the PT at the generator outlet side to obtain the partial discharge amount of the PT at the generator outlet side under the rated voltage.

6. The method for evaluating the PT insulation status at the generator outlet side according to claim 1, characterized in that: The simulation results include the primary side simulation current of the generator outlet side PT in normal operation, the simulation excitation characteristic curve, the relationship fitting curve between the primary side current and the short-circuit turns ratio, and the primary side current warning value when a preset inter-turn short circuit occurs in the generator outlet side PT; The step of determining the insulation state of the PT at the generator outlet side based on the simulation result, the actual PT primary side current, the offline detection result and the temperature monitoring result includes: The insulation status of the PT at the generator outlet is evaluated online based on the actual PT primary current, the simulated primary current of the PT at the generator outlet in normal operation, the fitting curve of the relationship between the primary current and the short-circuit turns ratio, the primary current warning value when the preset inter-turn short circuit occurs at the generator outlet PT, and the temperature monitoring results; When the online evaluation result shows that the generator outlet side PT is an abnormal PT, the generator outlet side PT insulation state is determined based on the simulated excitation characteristic curve and the offline detection result.

7. The method for evaluating the PT insulation status at the generator outlet side according to claim 6, characterized in that: The online evaluation of the PT insulation status at the generator outlet side includes: When the increase value of the actual PT primary current within the preset time period does not reach the preset value-added range, the insulation state of the PT at the generator outlet side is judged to be a turn-to-turn short-circuit state according to the actual PT primary current, the primary simulation current of the PT at the generator outlet side in normal operation, the relationship fitting curve between the primary current and the short-circuit turns ratio, and the primary current warning value when the PT at the generator outlet side has a preset turn-to-turn short-circuit; If it is determined that the insulation state of the PT on the generator outlet side is not a turn-to-turn short-circuit state and the temperature monitoring result shows that the temperature of the PT on the generator outlet side is lower than the preset temperature threshold, the online evaluation result is determined to be that the PT on the generator outlet side is a normal PT; otherwise, the online evaluation result is determined to be that the PT on the generator outlet side is an abnormal PT.

8. The method for evaluating the PT insulation status at the generator outlet side according to claim 6, characterized in that: The offline detection result includes the primary side excitation characteristic curve of the PT at the generator outlet side and the partial discharge amount of the PT at the generator outlet side at the rated voltage; The step of determining the PT insulation state at the generator outlet side based on the simulated excitation characteristic curve and the offline detection result includes: If the primary side excitation characteristic curve of the PT on the generator outlet side is inconsistent with the simulated excitation characteristic curve and / or the partial discharge of the PT on the generator outlet side at the rated voltage is greater than the preset partial discharge threshold, the insulation state of the PT on the generator outlet side is determined to be an abnormal PT insulation state.

9. A generator outlet side PT insulation status assessment system, characterized in that: include: A simulation module, used for simulating the normal operation state and the turn-to-turn short circuit state of the PT at the generator outlet side based on the simulation model of the PT at the generator outlet side, and obtaining simulation results; wherein the simulation model of the PT at the generator outlet side is constructed based on the original data of the PT at the generator outlet side; The primary side current monitoring module is used to monitor the primary side current of the generator outlet side PT in real time during operation based on the pre-built primary side current monitoring device of the generator outlet side PT to obtain the actual PT primary side current; An offline detection module is used to perform offline detection on the generator outlet side PT when the increase value of the actual PT primary side current within a preset time period reaches a preset value-added range to obtain an offline detection result; The temperature monitoring module is used to monitor the temperature of the PT at the generator outlet side and obtain the temperature monitoring results; The determination module is used to determine the PT insulation state at the generator outlet side based on the simulation result, the actual PT primary side current, the offline detection result and the temperature monitoring result, and obtain the PT insulation state determination result at the generator outlet side.

10. A machine-readable storage medium having instructions stored thereon, characterized in that: When the instruction is executed by a processor, the processor is configured to execute the method for evaluating the insulation status of a PT at the generator outlet side as claimed in any one of claims 1 to 8.

11. An electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method for evaluating the insulation status of the PT at the generator outlet side as described in any one of claims 1 to 8 is implemented.

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