Online state diagnosis method and system of transformer permanent magnet mechanism load-dependent capacity regulating switch

Abstract

The present application relates to the technical field of transformer, in particular to an on-line state diagnosis method and system of load capacity regulating switch of transformer permanent magnet mechanism. Stroke switches are installed at large and small capacity positions of the capacity regulating switch, a Hall current sensor is installed at an operating coil power supply circuit, and voltage and current transformers are installed at the input and output lines of the transformer; the switch hysteresis state is judged by detecting the stroke switch state and the operating coil current curve; the vacuum degree reduction degree is evaluated by analyzing the length of the operating coil current change curve of the vacuum tube; the coil burning state is diagnosed by monitoring the maximum value change of the operating coil power supply circuit current; the energy storage capacitor capacity loss is evaluated by detecting the length increase of the current change curve; and the burning degree is judged according to the transition resistance value calculated by the total loss, no-load loss and current according to the transformer type. The present application comprehensively diagnoses the key components of the capacity regulating switch on-line, improves the equipment reliability, realizes predictive maintenance, reduces the maintenance cost and power failure risk, and provides strong support for the intelligent management of power grid.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformers, in particular to an online state diagnosis method and system for a load-dependent capacity regulating switch of a transformer permanent magnet mechanism. BACKGROUND

[0002] In urban commercial areas, development zones, industrial zones with large diurnal load variation amplitude, and rural areas with large seasonal load variation amplitude, distribution transformers will have the phenomenon of "big horse pulling small cart" during periods with less load, resulting in a large amount of power loss. A capacity regulating transformer can be switched to operate in large or small capacity, and when the transformer has less load, it is switched to small capacity to save power. The key component of the capacity regulating transformer is its matching load-dependent capacity regulating switch. The performance of the load-dependent capacity regulating switch directly determines whether the capacity regulating transformer can normally regulate the capacity, so the performance of the load-dependent capacity regulating switch needs to be detected.

[0003] Currently, the performance of the load-dependent capacity regulating switch is detected before the switch is installed into the transformer or after the switch is installed into the transformer but before it is put into operation. The main detection instrument is a mechanical property tester, and the main detection method is to detect the consistency of the three-phase break in the switching process and the resistance value of the transition resistor under the condition that the main loop of the switch does not carry high voltage. Once the capacity regulating transformer is installed into the power system, no performance state monitoring is performed, but the load-dependent capacity regulating switch of the transformer may still have states such as sticking, reduced vacuum degree of the vacuum tube, burned operating coil, reduced capacity of the energy storage capacitor, and burned transition resistor. Only when the capacity regulating transformer fails, the switch is removed and tested under the condition of no electricity to determine the fault point. This will inevitably cause the capacity regulating transformer to suddenly exit operation and cause unplanned power outage accidents.

[0004] Therefore, the current performance detection method of the load-dependent capacity regulating switch of the transformer cannot detect the performance of the load-dependent capacity regulating switch in operation, and cannot accurately manage the capacity regulating transformer. A method and system for online performance diagnosis of the load-dependent capacity regulating switch of the transformer are needed to discover possible problems of the load-dependent capacity regulating switch of the transformer in operation as soon as possible. SUMMARY

[0005] In view of the problems in the prior art, the present application is proposed.

[0006] Therefore, the problem to be solved by the present application is how to solve the problem that the current performance detection method of the load-dependent capacity regulating switch of the transformer cannot detect the performance of the load-dependent capacity regulating switch in operation, and cannot accurately manage the capacity regulating transformer. A method and system for online performance diagnosis of the load-dependent capacity regulating switch of the transformer are needed to discover possible problems of the load-dependent capacity regulating switch of the transformer in operation as soon as possible.

[0007] To solve the above technical problems, the present application provides the following technical solutions:

[0008] In a first aspect, the embodiments of the present application provide an on-line state diagnosis method for a load-dependent capacity regulating switch of a transformer permanent magnet mechanism, which comprises,

[0009] A travel switch is installed at a large capacity position of the load-dependent capacity regulating switch to detect the state of the travel switch; the operating coil power supply loop current and the high voltage side current are detected;

[0010] The on-line state diagnosis comprises a load-dependent capacity regulating switch action sticking state, an operating coil burning state, an energy storage capacitor capacity loss state, and a transition resistance burning state.

[0011] The load-dependent capacity regulating switch action sticking state judgment comprises:

[0012] The state of the travel switch at the large capacity position after the capacity regulating command is issued is detected by a controller to determine whether the inherent action time is exceeded.

[0013] The position of a sudden change point of the operating coil power supply loop current is detected to determine the travel position of the switch sticking point; when the operating loop current is normal but the inherent action time is exceeded, it is determined that the travel switch is damaged.

[0014] The operating coil burning state judgment comprises:

[0015] The change of the maximum current in the operating coil power supply loop current change curve is detected; when the maximum current exceeds a preset threshold, it is determined that the operating coil is short-circuited and burned.

[0016] The energy storage capacitor capacity loss state judgment comprises:

[0017] The length of the operating coil power supply loop current change curve is detected; when the current change curve is lengthened in the switch opening and closing process, it is determined that the energy storage capacitor capacity starts to be lost.

[0018] When the length of the current change curve approaches the length of the current change curve corresponding to the minimum drivable operating coil energy storage capacitor, it is determined that the energy storage capacitor failure value is reached.

[0019] The transition resistance burning state judgment comprises:

[0020] For a high voltage coil star-angle conversion type capacity regulating transformer, a low voltage coil direct resistance is additionally converted to the high voltage side, the ratio of the high voltage coil direct resistance to the low voltage coil direct resistance is k, and R is calculated by the following formula:

[0021]

[0022] wherein R is the total resistance value of the high-low voltage transition resistance after the high voltage side, P0 is the no-load loss, P G is the total transition state loss, k is the ratio of the high-low voltage coil direct resistance, and I is the high voltage side current. total loss of the transformer in a large capacity state;

[0023] For the high-voltage coil series-parallel conversion type capacity regulating transformer, R is calculated by the following formula:

[0024]

[0025] The transition resistance damage degree is directly related to the R value, the difference degree of R from the normal value can determine the transition resistance burnout degree, and the controller stores and uploads information through 4G / 5G in real time processing and diagnosing data.

[0026] As a preferred scheme of the online state diagnosis method of the transformer permanent magnet mechanism on-load capacity regulating switch, wherein: the operating coil power supply loop is provided with a Hall current sensor, and a voltage current transformer is installed on the high-voltage side of the transformer.

[0027] As a preferred scheme of the online state diagnosis method of the transformer permanent magnet mechanism on-load capacity regulating switch, wherein: when the on-load capacity regulating switch includes a vacuum tube, the online state diagnosis further includes a vacuum degree reduction state of the vacuum tube.

[0028] As a preferred scheme of the online state diagnosis method of the transformer permanent magnet mechanism on-load capacity regulating switch, wherein: the judgment of the vacuum degree reduction state of the vacuum tube includes: detecting the length of the current change curve of the operating coil power supply loop of the vacuum tube;

[0029] When the length of the current change curve of the operating coil power supply loop of the vacuum tube is longer when closing and shorter when opening, it is judged that the vacuum degree of the vacuum tube is reduced;

[0030] By comparing the length of the current change curve of the operating coil power supply loop of the vacuum tube in the normal state and the completely air leakage state, the air leakage degree of the vacuum tube is determined.

[0031] In the second aspect, the embodiments of the present application provide an online state diagnosis system of a transformer permanent magnet mechanism on-load capacity regulating switch, which includes a construction module, a travel switch is deployed, the state of the travel switch and the operating coil current curve are detected, and it is judged whether the inherent action time is exceeded;

[0032] A comparison module analyzes the length of the current change curve of the operating coil of the vacuum tube, compares the normal state and the air leakage state, and detects the maximum value change of the operating coil power supply loop current;

[0033] A judgment module monitors the length increase of the current change curve of the operating coil power supply loop, calculates the transition resistance value according to the transformer type, the total loss, the no-load loss and the current, and judges the burnout degree;

[0034] An output module, the controller processes the diagnostic data in real time, stores and uploads information through 4G / 5G.

[0035] In a third aspect, an embodiment of the present application provides a computer device, comprising a memory and a processor, and the memory stores a computer program, wherein the computer program instructions are executed by the processor to implement the steps of the online state diagnosis method of the transformer permanent magnet mechanism load regulating switch.

[0036] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, which stores a computer program, wherein the computer program instructions are executed by the processor to implement the steps of the online state diagnosis method of the transformer permanent magnet mechanism load regulating switch.

[0037] The present application has the advantages that: the present application can realize online diagnosis of the action stuck state of the load regulating switch of the permanent magnet mechanism, the vacuum degree reduction state of the vacuum tube, the operation coil burning loss state, the energy storage capacitor capacity loss state, and the transition resistance burning loss state, and other key information.

[0038] The present application can realize the state data storage and uploading function of the load regulating switch, thereby assisting the transformer management personnel to plan power outage replacement or maintenance of the load regulating transformer in advance. DETAILED DESCRIPTION

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0040] Figure 1 Flowchart of the online state diagnosis method of the transformer permanent magnet mechanism load regulating switch;

[0041] Figure 2 Computer device diagram of the online state diagnosis method of the transformer permanent magnet mechanism load regulating switch;

[0042] Figure 3 Current curve schematic diagram of the operation coil power supply circuit when the switch is stuck in the online state diagnosis method of the transformer permanent magnet mechanism load regulating switch;

[0043] Figure 4 Current curve schematic diagram of the operation coil power supply circuit when the vacuum degree of the vacuum switch is reduced in the online state diagnosis method of the transformer permanent magnet mechanism load regulating switch;

[0044] Figure 5The current curve schematic diagram of the power supply loop when the operating coil of the on-line state diagnosis method of the transformer permanent magnet mechanism load regulating capacity switch is burned;

[0045] Figure 6 The current curve schematic diagram of the power supply loop when the energy storage capacitor capacity of the on-line state diagnosis method of the transformer permanent magnet mechanism load regulating capacity switch is reduced;

[0046] Figure 7 The principle diagram of the high voltage coil star-angle conversion type capacity regulating transformer of the on-line state diagnosis method of the transformer permanent magnet mechanism load regulating capacity switch;

[0047] Figure 8 The principle diagram of the high voltage coil series-parallel conversion type capacity regulating transformer of the on-line state diagnosis method of the transformer permanent magnet mechanism load regulating capacity switch. DETAILED DESCRIPTION

[0048] In order to make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0049] In the following description, a lot of specific details are set forth in order to facilitate a full understanding of the present application, but the present application can also be implemented in other ways different from the description, and those skilled in the art can make similar generalizations without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0050] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is separate or selectively excluded from other embodiments.

[0051] Embodiment 1

[0052] Reference Figures 1-2 For the first embodiment of the present application, the embodiment provides an on-line state diagnosis method of a transformer permanent magnet mechanism load regulating capacity switch, comprising,

[0053] S100: deploying a travel switch and detecting the travel switch state and the operating coil current curve, judging whether the switch is stuck and the stuck position;

[0054] S200: analyzing the length of the vacuum tube operating coil current change curve, comparing the normal and the air leakage state, detecting the maximum value change of the operating coil power supply loop current;

[0055] S300: Monitor the length of the operating coil power supply circuit current change curve, according to the transformer type, the transition resistance value is calculated by total loss, no-load loss and current, and the burning loss degree is judged;

[0056] S400: The controller processes the diagnosis data in real time, stores and uploads the information through 4G / 5G.

[0057] The stroke switch is installed at the size capacity position of the capacity regulating switch, the Hall current sensor is installed at the operating coil power supply circuit, and the voltage and current transformer is installed at the transformer input and output line side. The online state diagnosis mainly includes the on-load capacity regulating switch action sticking state, the vacuum tube vacuum degree reduction state, the operating coil burning state, the energy storage capacitor capacity loss state, and the transition resistance burning state.

[0058] The on-load capacity regulating switch action sticking state can be determined by the following steps:

[0059] The controller of the on-load capacity regulating switch detects whether the stroke switch at the large capacity position and the small capacity position of the capacity regulating switch exceeds the inherent action time range after sending the capacity regulating command, and whether the sticking occurs.

[0060] The position of the current mutation point of the operating coil power supply circuit of the capacity regulating switch can be used to determine the sticking point of the switch. When the operating circuit current is normal, it can be determined that the stroke switch is damaged.

[0061] The vacuum tube vacuum degree reduction state can be determined by the following steps:

[0062] The length of the current change curve of the operating coil power supply circuit of the vacuum tube switch in the capacity regulating switch is detected. If the length of the current change curve is longer when the vacuum tube is closed and shorter when the vacuum tube is opened, it is determined that the vacuum degree of the vacuum tube is reduced.

[0063] By comparing the length of the current change curve when the vacuum tube is normal and when the vacuum tube is completely leaked, the degree of leakage of the vacuum tube can be determined.

[0064] The operating coil burning state can be determined by the following steps:

[0065] The size of the maximum current in the current change curve of each operating coil power supply circuit of the capacity regulating switch is detected to determine whether the operating coil is in a short-circuit burning state.

[0066] The energy storage capacitor capacity loss state can be determined by the following steps:

[0067] The length of the current change curve of each operating coil power supply circuit of the capacity regulating switch is detected. If the length of the current change curve is longer during the opening and closing of the switch, it indicates that the capacity of the capacitor is starting to lose.

[0068] When the length of the change curve is similar to the length of the current change curve corresponding to the minimum driveable operating coil storage capacitor, the capacitor failure value is reached.

[0069] The transition resistance burnout state can be achieved by the following steps:

[0070] If the no-load loss of the transformer in a large capacity state is P0, the total loss is P D， The total loss of the transition resistance in series with the high and low voltage coils in the transformer capacity adjustment process is P G， The high voltage side current is I, and the total resistance value of the low voltage transition resistance converted to the high voltage side is R.

[0071] For a high voltage coil star-angle conversion type capacity adjustment transformer, another low voltage coil direct resistance is converted to the high voltage side, and the ratio of the high voltage coil to the low voltage coil direct resistance is k, then R is calculated by the following formula:

[0072]

[0073] For a high voltage coil series-parallel conversion type capacity adjustment transformer, R is calculated by the following formula:

[0074]

[0075] The transition resistance damage degree is directly related to the value of R, and the difference between R and the normal value can determine the transition resistance burnout degree.

[0076] Further, the embodiment also provides an online state diagnosis system of a transformer permanent magnet mechanism on-load capacity regulation switch, comprising,

[0077] The construction module deploys the travel switch and detects the travel switch state and the operating coil current curve, and judges whether the inherent action time is exceeded;

[0078] The comparison module analyzes the length of the vacuum tube operating coil current change curve, compares the normal and air leakage states, and detects the maximum value change of the operating coil power supply loop current.

[0079] The judgment module monitors the length increase of the operating coil power supply loop current change curve, calculates the transition resistance value according to the transformer type, the total loss, the no-load loss and the current, and judges the burnout degree.

[0080] The output module controls the controller to process the diagnosis data in real time, stores and uploads the information through 4G / 5G.

[0081] The embodiment also provides a computer device suitable for the online state diagnosis method of the load regulation switch of the transformer permanent magnet mechanism, including a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions to realize the online state diagnosis method of the load regulation switch of the transformer permanent magnet mechanism proposed in the above embodiment.

[0082] The computer device can be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operating system and the computer program in the non-volatile storage medium to run. The communication interface of the computer device is used to communicate with external terminals in a wired or wireless manner. The wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device can be a touch layer overlaid on the display screen, or a key, trackball or touchpad arranged on the shell of the computer device, or an external keyboard, touchpad or mouse, etc.

[0083] The embodiment also provides a storage medium having a computer program stored thereon, and the program is executed by a processor to realize the online state diagnosis method of the load regulation switch of the transformer permanent magnet mechanism proposed in the above embodiment.

[0084] In summary, by installing a travel switch at the large capacity position of the capacity regulation switch and combining with the detection of the operating coil current curve, real-time monitoring of the switch hysteresis state is realized. This method not only can determine whether hysteresis occurs, but also can accurately locate the hysteresis point position, which helps to discover and solve potential problems in time, and improves the reliability and safety of the system.

[0085] By analyzing the length of the vacuum tube operating coil current change curve and comparing the normal and leakage states, accurate diagnosis of the vacuum degree reduction state of the vacuum tube is realized. This non-intrusive detection method avoids the cumbersome process of traditional disassembly inspection, greatly improves the diagnosis efficiency, and reduces the maintenance cost.

[0086] By monitoring the maximum value change of the operating coil power supply loop current, early warning of the operating coil burnout state is realized. This method can discover problems in time before the coil is seriously damaged, effectively prevents equipment failure caused by coil burnout, and prolongs the service life of the equipment.

[0087] The dynamic monitoring of the capacity loss state of the energy storage capacitor is realized by detecting the length increase of the operating coil power supply loop current change curve. This method can accurately evaluate the remaining life of the capacitor, provide a scientific basis for equipment maintenance, and avoid sudden failures caused by capacitor failure.

[0088] According to the type of transformer, the transition resistance value is calculated by using total loss, no-load loss and current, and the quantitative evaluation of the transition resistance burnout degree is realized. This mathematical model-based diagnosis method improves the accuracy of diagnosis and provides a reliable basis for equipment management decision-making.

[0089] Through real-time processing of diagnostic data by the controller and uploading information through 4G / 5G, remote real-time monitoring and data analysis are realized. This intelligent diagnostic system greatly improves the efficiency of equipment management, realizes predictive maintenance, and reduces operation and maintenance costs.

[0090] In summary, the online state diagnosis method and system provided by the application realize comprehensive diagnosis of the key components of the transformer permanent magnet mechanism on-load capacity regulating switch through multi-dimensional real-time monitoring and intelligent analysis. This innovative diagnostic method not only improves the reliability and safety of the equipment, but also realizes predictive maintenance, greatly reduces maintenance costs and power outage risks. At the same time, the remote monitoring function of the system provides strong support for intelligent management of the power grid, which is of great significance to improve the operation efficiency and reliability of the entire power system.

[0091] Example 2

[0092] Reference Figure 2 - Figure 8 For the second embodiment of the application, the embodiment provides an online state diagnosis method for a transformer permanent magnet mechanism on-load capacity regulating switch. In order to verify the beneficial effects of the application, economic benefit calculation and simulation experiments are used for scientific demonstration.

[0093] The methods for diagnosing the stuck state of the on-load capacity regulating switch, the reduced vacuum state of the vacuum tube, the burned-out state of the operating coil, the capacity loss state of the energy storage capacitor, and the burned-out state of the transition resistance are described in detail below.

[0094] The transformer on-load capacity regulating switch can adjust the transformer to a large capacity or a small capacity state, and the corresponding capacity regulating switch has a large capacity position and a small capacity position,

[0095] When the capacity regulating switch is adjusted from the large capacity position to the small capacity position or from the small capacity position to the large capacity position, the normally open travel switches installed in the large capacity position and the small capacity position of the capacity regulating switch will be in the split state.

[0096] Therefore, the controller of the on-load tap changer determines whether the tap changer is stuck by detecting whether the travel switch of the large and small capacity position of the tap changer exceeds the inherent action time range after sending the tap command.

[0097] The characteristic of the permanent magnet mechanism is that the operating coil presents the characteristics of large in-state and in-closed state inductance and minimum in middle position inductance. Therefore, the normal current curve of the operating coil during the operation process is Figure 3 、 Figure 6 、 Figure 7 、 Figure 8 The middle solid line part presents the characteristics of first large and then small.

[0098] The controller determines the position of the stuck point of the tap changer by detecting the current of the operating coil supply circuit of the tap changer and distinguishing the position of the current curve mutation point. Figure 3 For example, the mutation point occurs at 16 ms after the coil is powered. According to the current curve during normal operation, the corresponding travel of the travel switch is measured in the no-power state during the production of the switch. The controller can determine the travel position of the stuck point of the switch according to the corresponding relationship data. If the operating circuit current is normal compared with the normal operating current, it can be determined that the travel switch is damaged.

[0099] When the vacuum tube is used in the tap changer, the self-closing force of the vacuum tube will decrease when the vacuum degree of the vacuum tube decreases. This will make the opening speed of the corresponding vacuum tube faster and the closing speed slower than normal, so that the length of the current change curve of the operating coil supply circuit of the vacuum tube switch of the tap changer will change. By detecting the length of the current change curve of the operating coil supply circuit of the vacuum tube switch of the tap changer, if the length of the current change curve of the vacuum tube closing speed becomes longer due to the slow speed, such as Figure 2 , and the length of the current change curve of the vacuum tube opening speed becomes shorter, such as Figure 2 , it is determined that the vacuum degree of the vacuum tube is reduced. By comparing the length of the current change curve of the vacuum tube opening and closing under the two conditions of normal vacuum tube and completely leaked vacuum tube, the degree of leakage of the vacuum tube can be determined.

[0100] When the operating coil of the tap changer is burned, most of the time, the insulation is damaged to cause inter-turn short circuit, a small number of inter-turn short circuits develop into a large number of inter-turn short circuits, until the coil is completely burned out or the current is too large to burn out the relay in the controller for supplying power to the coil. When the coil is inter-turn short-circuited, the resistance and reactance value of the coil will decrease accordingly, and the current flowing through the coil will increase, such as Figure 3 . Therefore, by detecting the maximum value of the current change curve of the operating coil supply circuit of the tap changer, it can be determined whether the operating coil is in the state of short circuit and burnout.

[0101] As the energy storage capacitor within a capacitive switch controller ages, its capacitance gradually decreases. This decrease in capacitance slows the switch's opening and closing speeds, resulting in longer opening and closing times, until the switch stops operating. Therefore, by monitoring the length of the current curve supplying each operating coil in the capacitive switch, if the current curve lengthens both during opening and closing, it indicates capacitor loss. When the curve length approaches the current curve length corresponding to the minimum drivable operating coil energy storage capacitor, the capacitor reaches failure, requiring replacement of the capacitor or the entire controller.

[0102] The three-phase symmetry of the three-phase capacity regulating transformer is only taken as an example. Figure 7 This is the A-phase principle diagram of the high-voltage coil star-delta conversion type capacity-regulating transformer, in which the tail of the high-voltage coil AX can be connected in delta or star, that is, connecting "Y" through the capacity-regulating switch contact 103 or 104 is star connection, and connecting "D" is delta connection; the low-voltage coil ax is composed of ax1, ax2 and ax3, ax1 and ax2 can be connected in parallel through contacts 203 and 205, and in series through 204; the high-voltage capacity-regulating transition circuit is composed of transition contact 101 in series with high-voltage transition resistor 102, and the low-voltage capacity-regulating transition circuit is composed of transition contact 201 in series with low-voltage transition resistor 202. The principle of this capacity-regulating transformer is: when the capacity is large, the high-voltage winding of the transformer is delta-connected, and the series-parallel parts of the low-voltage winding are connected in parallel to form Dyn 11 Connection method: When the capacity is low, the transformer's high-voltage winding is connected in star connection, and the low-voltage windings are connected in series (Yyn0). When the main contacts change from high capacity to low capacity, or vice versa, the transition circuit is connected in advance and removed after the main contacts have adjusted their capacity. This maintains power supply continuity during the transformer's capacity adjustment process, and the transition resistor limits the transformer's internal circulating current during this process.

[0103] When a transformer is switched from a large capacity to a small capacity, the high-voltage coil changes from delta connection to star connection. Circuit knowledge indicates that the voltage ratio between the high-voltage coil terminals at large and small capacity is 3:1. The turns ratio of the series-parallel sections ax1 and ax2 to ax3 on the low-voltage side is (3-1): (2-3). When the series-parallel sections ax1 and ax2 are connected in parallel, compared to when they are connected in series, the overall low-voltage coil turns ratio is 1:3. Therefore, the transformer's low-voltage output voltage remains unchanged after switching to a small capacity. Since the transformer coil's single-turn voltage decreases after switching to a small capacity, the transformer's core losses are reduced, thereby reducing the transformer's no-load losses and achieving energy savings when the transformer is lightly loaded or no-loaded.

[0104] Figure 7 (a) is the state of large capacity of the capacity regulating transformer. In the figure, 103, 104, 203, 204, and 205 are all in small capacity state. Figure 7The middle (b) state, in which the transition circuit 101, 201 is closed, and 103, 104, 203, 204, 205 are all disconnected. Because the action time of the capacity regulating switch is short, it is assumed that the load current before and after capacity regulation and during capacity regulation is not changed when converted to the high-voltage side I, and the transformer terminal voltage is also not changed. Compared with (a) and (b), because the transition resistance is small, the influence on the transformer coil terminal voltage is ignored. At this time, the number of turns of the high-voltage and low-voltage coils connected in the circuit in (a) and (b) is not changed, and according to the knowledge of the transformer, the no-load loss P0 of the transformer does not change under the condition that the number of turns of the coil and the form of the connected circuit are not changed. In (a), the transformer is in a large capacity state, that is, the no-load loss of the transformer is P0 when the transformer is in a large capacity state, Figure 7 (b) The no-load loss of the transformer in the transition state is also P0. Let the direct resistance of the high-voltage coil of the transformer be proportional to the direct resistance of the low-voltage coil multiplied by the square of the transformer ratio when converted to the high-voltage side, and the proportion is k:1. Then the load loss of the transformer, that is, the loss ratio of the high-voltage and low-voltage coils, is also k:1. Let Figure 7 The total loss of the transformer in (a) is P D Then Figure 7 The low-voltage coil loss in (a) is:

[0105]

[0106] The turn ratio of the low-voltage coils ax1, ax2 and ax3 is (3-1): (3-1): (2-3) according to the above principle analysis. Because the diameter of each turn of the coils ax1 and ax2 is usually half of that of ax3, the direct resistance ratio, that is, the loss ratio when the same current flows through, is also 2*(3-1):2* (3-1): (2-3). According to Figure 7 (a) and Figure 7 (b) can be known that the total resistance ratio of the low-voltage coils in the two states is 1:3, and the coil part connected in the circuit flows through the current I Figure 7 (b) state only increases the loss as follows:

[0107]

[0108] Let the total resistance of the high-voltage transition resistance 102 and the low-voltage side transition resistance 202 converted to the high-voltage side in series be R, then Figure 8 The total loss of the transformer in (b) is P G， Then according to the above analysis, the following active power balance equation can be listed:

[0109] + × + (1)

[0110] From equation (1), we can get (2)

[0111] Figure 8 This is the A-phase circuit diagram of a three-phase capacitance-regulating transformer with high-voltage coil series-parallel conversion. The high-voltage coil of the transformer consists of windings AX1 and AX2, which can be connected in parallel through capacitance-regulating switch contacts 303 and 305, and in series through 304; the low-voltage coil consists of windings ax1 and ax2, which can be connected in parallel through contacts 403 and 405, and in series through 404; the high-voltage capacitance-regulating transition circuit consists of transition contact 301 in series with high-voltage transition resistor 302, and the low-voltage capacitance-regulating transition circuit consists of transition contact 401 in series with low-voltage transition resistor 402. The principle of this capacitance-regulating transformer is: when the capacity is large, the high-voltage and low-voltage coil windings of the transformer are connected in parallel to form Dyn 11 The connection method is that the three phases of the high voltage coil are delta-connected and the low voltage coil is star-connected. When the capacity is small, the high voltage and low voltage coil windings of the transformer are connected in series to form the same Dyn 11 Connection method. The transition circuit is connected to the circuit in advance when the capacity adjustment main contacts change from a high capacity state to a low capacity state, or from a small capacity to a high capacity state, and is removed from the circuit after the main contacts have adjusted their capacity, thereby maintaining power supply continuity during the transformer capacity adjustment process. The transition resistor limits the internal circulating current of the transformer during this process.

[0112] The transformer is Dyn when it is large or small capacity. 11 The connection method is simple, and because the number of turns of the transformer's high and low voltage coils is doubled when the capacity is reduced from large to small, the output voltage on the low voltage side remains unchanged. Since the voltage per turn of the transformer coil is reduced to half of that when the capacity is reduced, the transformer core loss is reduced, thereby reducing the transformer's no-load loss and achieving energy saving when the transformer is lightly loaded or no-loaded.

[0113] Figure 8 (a) is the state of large capacity of the capacity regulating transformer. In the figure, 303, 304, 403, 404 and 405 are all in small capacity when they are shifted. Figure 8 In state (b), in this state, transition circuits 301 and 401 are closed, and 303, 304, 403, 404, and 405 are all disconnected. Because the action time of the capacity adjustment switch is short, it is assumed that the load current converted to the high-voltage side I before, after, and during the capacity adjustment remains unchanged, and the transformer terminal voltage remains unchanged. Comparing (a) and (b), due to the small transition resistance, the impact on the transformer coil terminal voltage is negligible. At this time, the number of turns of the high and low voltage coils connected to the circuit in Figures (a) and (b) remains unchanged. According to transformer knowledge, the no-load loss P0 of the transformer remains unchanged when the number of coil turns and the form of the connected circuit remain unchanged. Figure (a) shows the large-capacity state of the transformer, that is, when the large-capacity no-load loss of the transformer is P0, Figure 8(b) the transformer transition state under no-load loss is also P0. Since the diameter of each turn of the coils ax1, ax2 and AX1, AX2 is usually equal, Figure 8 (a) and Figure 5 (b) it is known that the total resistance ratio of the coils in the two states is 1:2, and when the current I is unchanged Figure 8 (b) the state is 2 times the coil loss of the state (a), assuming that the total resistance value of the high-voltage transition resistance 302 and the low-voltage side transition resistance 402 converted to the high-voltage side and connected in series is R, Figure 7 (b) the total loss of the transformer is P G， Therefore, according to the above analysis, the following active power balance equation can be listed:

[0114] × + ×R (3)

[0115] From equation (3), we can get (4)

[0116] The damage degree of the transition resistance is directly related to the value of R. The difference between R and the normal value can determine the degree of transition resistance burnout. Although there are approximate assumptions in the calculation process of equations (1) to (4), and the resistance will be different with the temperature value, the normal value of the transition resistance is modified to the rated temperature rise of the transformer, and the measured value after the capacity adjustment under the critical conversion current condition, and the transition resistance burnout alarm threshold is set to 1.3-1.5 times of the normal value, which can avoid judgment errors.

[0117] In the above diagnosis method, the travel switch on-off signals of the large and small capacity positions of the capacity regulating switch are needed, so the travel switches need to be installed at the large and small capacity positions of the capacity regulating switch; the current of each operating coil supply circuit of the capacity regulating switch needs to be monitored, so the Hall current sensor needs to be installed in the above circuit; the real-time active power of the incoming and outgoing lines of the capacity regulating transformer needs to be monitored, and the difference is the total loss of the transformer, so the voltage and current transformers need to be installed at the incoming and outgoing lines of the capacity regulating transformer; and the controller of the permanent magnet mechanism on-load capacity regulating switch is needed for switch control, and the controller should also have one or several of the above online state diagnosis methods, and have the function of storing and uploading diagnosis information through 4G or 5G. Therefore, an online state diagnosis system for a transformer on-load capacity regulating switch includes one or several of the above online state diagnosis methods; includes travel switches installed at the large and small capacity positions of the capacity regulating switch, Hall current sensors installed at each operating coil supply circuit of the capacity regulating switch, and voltage and current transformers installed at the incoming and outgoing lines of the capacity regulating transformer; includes a controller that can realize capacity regulating switch control, online state diagnosis and storage, and upload diagnosis information through 4G or 5G.

[0118] Figure 8 and ​

[0119] A.X: two ends of transformer high voltage coil AX; a, x: two ends of transformer low voltage coil ax; X1-X7 are transformer high voltage coil taps; AX: high voltage coil; AX1, AX2: windings contained in high voltage coil; ax1, ax2, ax3: windings contained in low voltage coil; 101: star-delta conversion type capacity regulating switch high voltage transition contact; 102: star-delta conversion type capacity regulating switch high voltage transition resistance; 103: star-delta conversion type capacity regulating switch high voltage delta connection main contact; 104: star-delta conversion type capacity regulating switch high voltage star connection main contact; 201: star-delta conversion type capacity regulating switch low voltage transition contact; 202: star-delta conversion type capacity regulating switch low voltage transition resistance; 203: star-delta conversion type capacity regulating switch low voltage parallel main contact 1; 204: star-delta conversion type capacity regulating switch low voltage series main contact; 205: star-delta conversion type capacity regulating switch low voltage parallel main contact 2; 301: series-parallel conversion type capacity regulating switch high voltage transition contact; 302: series-parallel conversion type capacity regulating switch high voltage transition resistance; 303: series-parallel conversion type capacity regulating switch high voltage parallel main contact 1; 304: series-parallel conversion type capacity regulating switch high voltage series main contact; 305: series-parallel conversion type capacity regulating switch high voltage parallel main contact 2; 401: series-parallel conversion type capacity regulating switch low voltage transition contact; 402: series-parallel conversion type capacity regulating switch low voltage transition resistance; 403: series-parallel conversion type capacity regulating switch low voltage parallel main contact 1; 404: series-parallel conversion type capacity regulating switch low voltage series main contact; 405: series-parallel conversion type capacity regulating switch low voltage parallel main contact 2.

[0120] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and all modifications or replacements should be covered in the scope of the claims of the present application.​

Claims

1. A method for online status diagnosis of a transformer permanent magnet mechanism on-load capacity switching device, characterized by: include, Install a limit switch at the large and small capacity positions of the on-load capacity-changing switch to detect the limit switch status, the operating coil power supply circuit current, and the high-voltage side current; Online status diagnosis includes the stuck state of on-load capacity regulating switch, the burnout state of operating coil, the loss state of energy storage capacitor capacity, and the burnout state of transition resistor; The determination of the stuck state of the on-load capacity regulating switch includes: The controller detects the status of the travel switches at the large and small capacity positions after the capacity adjustment command is issued to determine whether the inherent action time has been exceeded; Detect the position of the sudden change point of the current in the power supply circuit of the operating coil and determine the travel position of the switch stagnation point; when the current in the operating circuit is normal but exceeds the inherent action time, it is judged that the travel switch is damaged; The determination of the burnout state of the operating coil includes: Detect the change of the maximum current in the current change curve of the operating coil power supply circuit; when the maximum current exceeds the preset threshold, it is determined that the operating coil is short-circuited and burned; The determination of the energy storage capacitor capacity loss state includes: Detect the length of the current change curve of the operating coil power supply circuit; when the current change curve becomes longer in both the opening and closing processes of the switch, it is determined that the energy storage capacitor capacity has begun to lose capacity; When the length of the current change curve approaches the length of the current change curve corresponding to the minimum drivable operating coil energy storage capacitor, it is determined that the energy storage capacitor failure value has been reached; The judgment of the burnout state of the transition resistor includes: For the high-voltage coil star-delta conversion type capacity regulating transformer, suppose the direct resistance ratio of the low-voltage coil to the low-voltage coil after the low-voltage coil is converted to the high-voltage side is k, then R is calculated using the following formula: Among them, R is the total resistance of the high-voltage and low-voltage transition resistors after the high-voltage side, P0 is the no-load loss, P G is the total loss in the transition state, k is the direct resistance ratio of the high and low voltage coils, and I is the current on the high voltage side; is the total loss of the transformer in the large capacity state; For high-voltage coil series-parallel conversion type capacity regulating transformer, R is calculated using the following formula: The degree of damage to the transition resistor is directly related to the R value. The degree of difference between R and the normal value can determine the degree of burnout of the transition resistor. The controller processes diagnostic data in real time and stores the information via 4G / 5G.

2. The online state diagnosis method of the on-load capacity-changing switch of the permanent magnet mechanism of the transformer according to claim 1, characterized in that: A Hall current sensor is installed in the operating coil power supply circuit, and a voltage and current transformer is installed on the high voltage side of the transformer.

3. The online state diagnosis method of the on-load capacity-changing switch of the permanent magnet mechanism of the transformer according to claim 1 is characterized in that: When the on-load capacity-changing switch includes a vacuum tube, the online status diagnosis also includes a vacuum degree reduction state of the vacuum tube.

4. The online state diagnosis method of the on-load capacity-changing switch of the permanent magnet mechanism of the transformer according to claim 3 is characterized in that: The determination of the vacuum degree reduction state of the vacuum tube includes: detecting the length of the current change curve of the power supply circuit of the vacuum tube operating coil; When the current change curve of the power supply circuit of the vacuum tube operating coil becomes longer when the switch is closed and becomes shorter when the switch is opened, it is judged that the vacuum degree of the vacuum tube is reduced; The degree of vacuum tube leakage can be determined by comparing the length of the current change curve of the vacuum tube operating coil power supply circuit in the normal state and the complete leakage state.

5. An online state diagnosis system for a transformer permanent magnet mechanism on-load capacity-adjusting switch, based on the online state diagnosis method for a transformer permanent magnet mechanism on-load capacity-adjusting switch according to any one of claims 1 to 4, characterized in that: Also includes, Build a module, deploy a travel switch, and detect the travel switch status and operating coil current curve to determine whether the inherent operating time has been exceeded; The comparison module analyzes the length of the current change curve of the vacuum tube operating coil, compares the normal and leaking states, and detects the maximum current change in the operating coil power supply circuit; The judgment module monitors the increase in the length of the current change curve of the operating coil power supply circuit, calculates the transition resistance value based on the total loss, no-load loss and current according to the transformer type, and determines the degree of burnout; The output module and controller process diagnostic data in real time, store and upload the information via 4G / 5G.

6. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the online status diagnosis method of the on-load capacity-changing switch of the permanent magnet mechanism of the transformer are implemented as described in any one of claims 1 to 4.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the online status diagnosis method of the on-load capacity-changing switch of the permanent magnet mechanism of the transformer are implemented as described in any one of claims 1 to 4.

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