Method for selecting and calculating main elements of capacity-regulating and voltage-regulating switch of transformer

Abstract

The invention discloses a method for selecting and calculating main elements of a capacity-regulating and voltage-regulating switch of a transformer, which relates to the technical field of transformers and comprises a method for selecting and calculating rated voltage and current of high and low voltage main contacts, transition contacts, high transition resistors and low transition resistors of a capacity-regulating switch of a permanent magnetic mechanism. Selecting and calculating rated voltage and current of a permanent magnetic mechanism voltage regulating switch gear selection contact, a switching main contact, a switching transition contact and a transition resistor; the invention discloses a transition resistance wire diameter or wire type selection method. According to the method, the optimization design of the capacity-regulating and voltage-regulating switch of the transformer is facilitated, and the voltage-regulating transition process is divided into other gears to N gears and from N gears to other gears through an analytical calculation method comprising a high-voltage side star-delta conversion type capacity-regulating switch and a high-voltage side series-parallel connection type capacity-regulating switch; not only is important guidance provided for design and application of the capacitance and voltage regulating switch, but also gear-by-gear voltage regulating and cross-gear voltage regulating processes are considered.

Description

Technical Field

[0001] The invention relates to the technical field of transformers, and in particular to a calculation method for selecting main components of a transformer capacity and voltage regulating switch. Background Art

[0002] With the rapid development of power systems, the capacity and voltage regulation functions of transformers play a vital role in ensuring the stable operation of power grids. Traditional transformer capacity and voltage regulation switches mainly rely on mechanical operating mechanisms. After years of development, the relevant technologies have met market demand to a certain extent, but there are still many shortcomings. The capacity-regulating transformer can be switched to large and small capacities. When the transformer is under light load, it switches to a small capacity to save energy. Therefore, 10kV distribution system capacity-regulating transformers have also begun to be gradually used in power grids in recent years, but there is currently no typical component selection and calculation method for 10kV capacity-regulating switches.

[0003] In addition, on-load voltage-changing transformers have been used in power systems with voltage levels of 35kV and above for many years. The on-load voltage-changing switches are mostly driven by motors and consist of a gear selection switch and a switching switch. Each time the voltage is adjusted, one gear is raised or lowered. The voltage between the transformer stages is a constant value. The buck-boost circuit is fixed, and there is a fixed analysis method, which can facilitate the selection and calculation of component parameters. In recent years, permanent magnet mechanisms have gradually become a research hotspot in the field of transformer capacity-changing and voltage-changing switches due to their simple structure, reliable operation, and fast response speed. However, in the design process of permanent magnet mechanism capacity-changing and voltage-changing switches, how to reasonably select the rated voltage, current, and transition resistance wire diameter or line type of the main components is still a problem that needs to be solved urgently.

[0004] In recent years, due to the rapid development of permanent magnet mechanisms, many permanent magnet mechanism-driven on-load tap-changers have been applied to 10kV distribution systems. Since the step-up and step-down circuits of permanent magnet mechanism tap-changers are significantly different from those of conventional motor-driven on-load tap-changers, there is no typical component selection and calculation method. Summary of the invention

[0005] In view of the above-mentioned problems, the present invention is proposed.

[0006] Therefore, the technical problem solved by the present invention is: the prior art lacks an effective calculation method for selecting the main components of the transformer capacity regulating and voltage regulating switch, as well as how to calculate and select the voltage and current of the main components of each capacity regulating and voltage regulating switch of the permanent magnet mechanism, and how to select the transition resistance wire diameter or line type.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for selecting and calculating the main components of a transformer capacity regulating and voltage regulating switch, including a method for selecting and calculating the rated voltage and current of high and low voltage main contacts, transition contacts and high and low transition resistors of a permanent magnet mechanism capacity regulating switch; a method for selecting and calculating the rated voltage and current of a gear selection contact, a switching main contact, a switching transition contact and a transition resistor of a permanent magnet mechanism voltage regulating switch; and a method for selecting the wire diameter or line type of a transition resistor.

[0008] As a preferred scheme of the calculation method for selecting the main components of the transformer capacity regulating and voltage regulating switch described in the present invention, the method for selecting the rated voltage and current of the high and low voltage main contacts, transition contacts and high and low transition resistances of the permanent magnet mechanism capacity regulating switch includes establishing circuit diagrams before capacity regulation, during capacity regulation and after capacity regulation to a small capacity when the transformer is large in capacity, assuming that the rated current of the transformer at a large capacity flows through the transformer before capacity regulation in the circuit diagram, the critical conversion current flows through the transformer during capacity regulation, and the rated current of the transformer at a small capacity flows through the transformer after capacity regulation, calculating the voltage and current of each main component of the capacity regulating switch in the circuit, and selecting the standard voltage and current above the maximum value as the rated value; the calculation method should calculate the two extreme cases of load power factor of 1 or 0 respectively.

[0009] As a preferred scheme of the calculation method for selecting the main components of the transformer capacity regulating and voltage regulating switch described in the present invention, the calculation method for selecting the rated voltage and current of the gear selection contact, switching main contact, switching transition contact and transition resistor of the permanent magnet mechanism voltage regulating switch includes establishing circuit diagrams when all gears of the transformer are in steady state, when all gears are incorporated into the transition circuit, and when all gears are disconnected from the main circuit, assuming that the rated current flows through the transformer in the circuit diagram, calculating the voltage and current of each main component of the capacity regulating switch in the circuit, and selecting the standard voltage and current above the maximum absolute value of each as the rated value.

[0010] As a preferred scheme for the calculation method for selecting the main components of the transformer capacity-adjusting and voltage-adjusting switch described in the present invention, the capacity-adjusting switch includes a high-voltage side star-delta conversion type and a high-voltage side series-parallel conversion type; the circuit diagram established in the capacity adjustment of the high-voltage side star-delta conversion type includes three states: the transition contact is closed and the main capacity-adjusting contact connects the high-voltage winding of the transformer in delta to the low-voltage winding in parallel, the transition contact is closed and the main capacity-adjusting contacts are all disconnected, and the transition contact is closed and the main capacity-adjusting contact connects the high-voltage winding of the transformer in star to the low-voltage winding in series; the circuit diagram established in the capacity adjustment of the high-voltage side series-parallel conversion type includes three states: the transition contact is closed and the main capacity-adjusting contact is respectively connected in parallel with the high and low voltage windings of the transformer, the transition contact is closed and the main capacity-adjusting contacts are all disconnected, and the transition contact is closed and the main capacity-adjusting contact is respectively connected in series with the high and low voltage windings of the transformer.

[0011] As a preferred scheme for the calculation method for selecting the main components of the transformer capacity regulating and voltage regulating switch described in the present invention, the method for selecting the wire diameter or line type of the transition resistor includes that the transition resistors of the capacity regulating switch and the voltage regulating switch are made of nickel-chromium alloy Ni80Cr20 or iron-chromium-aluminum alloy Cr25Al5 or carbon fiber; when the transition resistor is made of alloy, its wire diameter is selected according to the working current density of 60 to 90A / mm2; when carbon fiber is used, the model is selected according to the working current being 15 to 20 times the long-term passable current.

[0012] As a preferred solution of the calculation method for selecting the main components of the transformer capacity and voltage regulating switch of the present invention, the critical switching current includes calculating the critical switching current by using the rated voltage, rated large capacity, rated small capacity, no-load loss and load loss of the transformer at large capacity and small capacity of the transformer, which is expressed as:

[0013]

[0014] Among them, I LJ represents the critical switching current, U represents the rated voltage of the transformer, S ND Indicates the rated maximum capacity of the capacity-adjusting transformer, S NX Indicates the rated minimum capacity of the capacity-regulating transformer, P 0D Indicates the no-load loss of the transformer when it is large in capacity, P 0X Indicates the no-load loss of the transformer when the capacity is small, P KD Load loss when transformer is large capacity, P KX Load loss when the transformer is small capacity.

[0015] As a preferred solution of the calculation method for selecting the main components of the transformer capacity regulating and voltage regulating switch of the present invention, the critical switching current also includes another calculation method, which uses the rated voltage, rated large capacity, rated small capacity, no-load loss and load loss of the transformer at large capacity and small capacity, and the no-load current and short-circuit impedance of the transformer at large capacity and small capacity to calculate the critical switching current, which is expressed as:

[0016]

[0017] Among them, I 0D % indicates the no-load current when the transformer is large capacity, I 0X % indicates the no-load current of the transformer when the capacity is small, U KD % indicates the short-circuit impedance of the transformer when it is large in capacity, U KX % represents the short-circuit impedance of the transformer when the capacity is small.

[0018] Another object of the present invention is to provide a main component selection and calculation system for a transformer capacity-adjusting and voltage-regulating switch, which can calculate the voltage and current of the main components of each capacity-adjusting and voltage-regulating switch of the permanent magnet mechanism, and select the standard voltage and current above the absolute maximum value of each as the rated value, thereby solving the problem that the current prior art lacks an effective selection and calculation method for the main components of the capacity-adjusting and voltage-regulating switch.

[0019] As a preferred solution of the main component selection calculation system of the transformer capacity regulating and voltage regulating switch described in the present invention, it includes: a capacity regulating calculation module, a voltage regulating calculation module, and a selection module; the capacity regulating calculation module is used for the rated voltage and current selection calculation method of the high and low voltage main contacts, transition contacts and high and low transition resistances of the permanent magnetic mechanism capacity regulating switch; the voltage regulating calculation module is used for the rated voltage and current selection calculation method of the gear selection contact, switching main contact, switching transition contact and transition resistance of the permanent magnetic mechanism voltage regulating switch; the selection module is used for the selection method of the transition resistance wire diameter or line type.

[0020] A computer device includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of a calculation method for selecting main components of a transformer capacity and voltage regulating switch.

[0021] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a calculation method for selecting main components of a transformer capacity-regulating and voltage-regulating switch.

[0022] Beneficial effects of the present invention: The calculation method for selecting the main components of the transformer capacity-adjusting and voltage-regulating switch provided by the present invention establishes a circuit diagram for the main components of the permanent magnet mechanism capacity-adjusting and voltage-regulating switch, and calculates the voltage and current of the main components of each capacity-adjusting and voltage-regulating switch, selecting the standard voltage and current above the maximum value as the rated value, which not only provides an effective calculation method for the component selection of the transformer capacity-adjusting and voltage-regulating switch, but also facilitates the optimization design of the transformer capacity-adjusting and voltage-regulating switch; by including the analysis and calculation method of the high-voltage side star-delta conversion type and the high-voltage side series-parallel type capacity-adjusting switch, not only the application scope of the selection method becomes wider, but also provides important guidance for the design and application of the capacity-adjusting and voltage-regulating switch; by dividing the voltage regulation transition process into any other gear to N gear and from N gear to any other gear, not only the gear-by-gear voltage regulation and cross-gear voltage regulation process are taken into account, but also the applicability of the voltage regulating switch is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 An overall flow chart of a calculation method for selecting main components of a transformer capacity and voltage regulating switch provided in the first embodiment of the present invention.

[0025] Figure 2 A high-voltage star-delta conversion type capacity regulating transformer circuit diagram for a calculation method for selecting main components of a transformer capacity regulating and voltage regulating switch provided in the second embodiment of the present invention.

[0026] Figure 3 A high-voltage series-parallel conversion type capacity regulating transformer circuit diagram for a calculation method for selecting main components of a transformer capacity regulating and voltage regulating switch provided in the second embodiment of the present invention.

[0027] Figure 4 A circuit diagram related to voltage regulation level 1 for a method for selecting the main components of a transformer capacity regulating and voltage regulating switch provided in the second embodiment of the present invention.

[0028] Figure 5 A circuit diagram related to voltage regulation 2-speed for selecting the main components of a transformer capacity regulating and voltage regulating switch provided in the second embodiment of the present invention.

[0029] Figure 6 A circuit diagram related to voltage regulation 3 gears for selecting the main components of a transformer capacity regulating and voltage regulating switch provided in the second embodiment of the present invention.

[0030] Figure 7 A circuit diagram related to a four-speed voltage regulation method for selecting the main components of a transformer capacity regulating and voltage regulating switch provided in the second embodiment of the present invention.

[0031] Figure 8 A circuit diagram related to a five-speed voltage regulation method for selecting the main components of a transformer capacity regulating and voltage regulating switch provided in the second embodiment of the present invention.

[0032] Fig. 9 An overall flow chart of a main component selection calculation system for a transformer capacity and voltage regulating switch provided in the third embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0034] Example 1, reference Figure 1 , which is an embodiment of the present invention, provides a method for calculating the selection of main components of a transformer capacity regulating and voltage regulating switch, including:

[0035] S1: Calculation method for selecting rated voltage and current of high and low voltage main contacts, transition contacts and high and low transition resistances of permanent magnet mechanism capacity regulating switch.

[0036] Furthermore, the calculation method for selecting the rated voltage and current of the high and low voltage main contacts, transition contacts and high and low transition resistances of the permanent magnet mechanism capacity regulating switch includes establishing circuit diagrams before capacity regulation when the transformer is large, during capacity regulation and after capacity regulation to small capacity respectively, assuming that the rated current of large capacity flows through the transformer before capacity regulation in the circuit diagram, the critical conversion current flows through the transformer during capacity regulation, and the rated current of small capacity flows through the transformer after capacity regulation, calculating the voltage and current of each main component of the capacity regulating switch in the circuit, and selecting the standard voltage and current above the maximum value as the rated value.

[0037] It should be noted that the calculation method should calculate the two extreme cases of load power factor being 1 or 0 respectively.

[0038] It should also be noted that the capacity regulating switch includes a high-voltage side star-delta conversion type and a high-voltage side series-parallel conversion type;

[0039] The circuit diagram established in the capacity regulation of the star-delta conversion type on the high-voltage side includes three states: the transition contact is closed and the main regulating capacity contact connects the high-voltage winding of the transformer in delta to the low-voltage winding in parallel, the transition contact is closed and the main regulating capacity contacts are all disconnected, and the transition contact is closed and the main regulating capacity contact connects the high-voltage winding of the transformer in star to the low-voltage winding in series; the circuit diagram established in the capacity regulation of the series-parallel conversion type on the high-voltage side includes three states: the transition contact is closed and the main regulating capacity contact is respectively connected in parallel with the high and low voltage windings of the transformer, the transition contact is closed and the main regulating capacity contacts are all disconnected, and the transition contact is closed and the main regulating capacity contact is respectively connected in series with the high and low voltage windings of the transformer.

[0040] It should also be noted that the critical switching current includes the calculation of the critical switching current using the transformer rated voltage, rated large capacity, rated small capacity, transformer no-load loss and load loss at large capacity and small capacity, expressed as:

[0041]

[0042] Among them, ILJ represents the critical switching current, U represents the rated voltage of the transformer, S ND Indicates the rated maximum capacity of the capacity-adjusting transformer, S NX Indicates the rated minimum capacity of the capacity-regulating transformer, P 0D Indicates the no-load loss of the transformer when it is large in capacity, P 0X Indicates the no-load loss of the transformer when the capacity is small, P KD Load loss when transformer is large capacity, P KX Load loss when the transformer is small capacity.

[0043] It should also be noted that the critical switching current also includes another calculation method, which uses the transformer rated voltage, rated large capacity, rated small capacity, transformer no-load loss and load loss at large capacity and small capacity, transformer no-load current and short-circuit impedance at large capacity and small capacity to calculate the critical switching current, expressed as:

[0044]

[0045] Among them, I 0D % indicates the no-load current when the transformer is large capacity, I 0X % indicates the no-load current of the transformer when the capacity is small, U KD % indicates the short-circuit impedance of the transformer when it is large in capacity, U KX % represents the short-circuit impedance of the transformer when the capacity is small.

[0046] S2: Calculation method for selecting the rated voltage and current of the gear selection contacts, switching main contacts, switching transition contacts and transition resistors of the permanent magnet mechanism voltage regulating switch.

[0047] Furthermore, the calculation method for selecting the rated voltage and current of the permanent magnet mechanism voltage regulating switch gear selection contacts, switching main contacts, switching transition contacts and transition resistors includes establishing circuit diagrams when all gears of the transformer are in steady state, when all gears are incorporated into the transition circuit, and when all gears are disconnected from the main circuit, assuming that the rated current flows through the transformer in the circuit diagram, calculating the voltage and current of each main component of the capacity regulating switch in the circuit, and selecting the standard voltage and current above their respective absolute maximum values ​​as the rated values.

[0048] S3: Method for selecting transition resistor wire diameter or wire type.

[0049] Furthermore, the method for selecting the wire diameter or line type of the transition resistor includes using nickel-chromium alloy Ni80Cr20 or iron-chromium-aluminum alloy Cr25Al5 or carbon fiber material for the transition resistor of the capacitance regulating switch and the voltage regulating switch.

[0050] It should be noted that when the transition resistor is made of alloy, its wire diameter is selected according to the working current density of 60 to 90A / mm2.

[0051] It should also be noted that when using carbon fiber, the model is selected based on the working current being 15-20 times the long-term current that can pass through.

[0052] Example 2, reference Figure 2-Figure 8 , which is an embodiment of the present invention, provides a calculation method for selecting the main components of a transformer capacity and voltage regulating switch. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0053] First of all, the capacity regulating switch and voltage regulating switch of the capacity regulating and voltage regulating transformer are not allowed to operate at the same time. Although the capacity regulating and voltage regulating switch may be designed as an integrated structure, its capacity regulating circuit and voltage regulating circuit can be analyzed separately. Therefore, the following analysis process will analyze the capacity regulating circuit and voltage regulating circuit separately.

[0054] At present, the main types of capacity regulating transformers are star-delta connection conversion of high-voltage coils, series-parallel conversion of part of the low-voltage coil windings, and series-parallel connection of high and low voltage coil windings. The three-phase circuit of the three-phase capacity regulating transformer is the same. Both types of capacity regulating transformers are analyzed using the A-phase circuit diagram.

[0055] Figure 2 The A-phase circuit diagram of the three-phase capacity-adjusting transformer with high-voltage coil star-delta connection conversion and low-voltage coil partial winding series-parallel conversion. The tail of the high-voltage coil AX can be connected in delta or star, that is, through the capacity-adjusting switch contact 103 or 104, "Y" is connected for star connection, and "D" is connected for 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-adjusting transition circuit is composed of the transition contact 101 connected in series with the high-voltage transition resistor 102, and the low-voltage capacity-adjusting transition circuit is composed of the transition contact 201 connected in series with the low-voltage transition resistor 202. The principle of the transformer is: when the capacity is large, the high-voltage winding of the transformer is connected in corners, and the series-parallel parts of the low-voltage windings are connected in parallel to form a Dyn11 connection; when the capacity is small, the high-voltage winding of the transformer is connected in star, and the series-parallel parts of the low-voltage windings are connected in series to form a Yyn0 connection. When the main contact of the capacity adjustment changes from a large capacity state to a small capacity state, or from a small capacity to a large capacity, the transition circuit is connected to the circuit in advance and exits the circuit after the main contact is adjusted, thereby maintaining the power supply continuity during the transformer capacity adjustment process. The transition resistor limits the internal circulating current of the transformer during this process.

[0056] When the transformer capacity changes from large to small, the high-voltage coil changes from delta connection to star connection. According to circuit knowledge, the voltage ratio of the high-voltage coil terminal when the capacity is large to that when the capacity is small is The ratio of the turns of the series-parallel part ax1 and ax2 to the turns of ax3 on the low-voltage side When the turns of the series-parallel parts ax1 and ax2 are connected in parallel, the turns ratio of the entire low-voltage coil is compared with that of the series parts. Therefore, the output voltage on the low-voltage side of the transformer remains unchanged after the capacity is adjusted to a small value. Since the voltage of the transformer coil per turn becomes lower after the capacity is adjusted to a small value, the transformer core loss is reduced, thereby reducing the transformer no-load loss and achieving energy saving when the transformer is lightly loaded or no-loaded.

[0057] When calculating the parameters of the main components of the capacity-adjusting switch, circuit diagrams are established before capacity adjustment when the transformer is large in capacity, during capacity adjustment, and after capacity adjustment to a small capacity. Figure 2 (a) is the circuit diagram before the transformer is adjusted when the capacity is large. The transition contacts 101 and 201 are disconnected, the transformer high-voltage winding AX is connected in delta through 103, and the low-voltage side windings ax1 and ax2 are connected in parallel through 203 and 205. (b), (c), and (d) are the circuit diagrams of the transformer during capacity adjustment. (b) is the circuit when the transition contacts 101 and 201 are closed and the main capacity adjustment contact 103 connects the transformer high-voltage winding AX in delta, and the low-voltage side 203 and 205 connect the transformer low-voltage windings ax1 and ax2 in parallel. (c) is the circuit when the transition contacts 101 and 201 are closed and the main capacity adjustment contacts 103, 104, 203, 204, and 205 are all disconnected. (d) is the circuit when the transition contacts 101 and 201 are closed, the main capacity adjustment contact 104 connects the transformer winding AX in star, and the low-voltage side windings ax1 and ax2 are connected in series through 204. (e) is the circuit diagram after the transformer is adjusted from large capacity to small capacity. The transition contacts 101 and 201 are disconnected, the transformer high-voltage winding AX is connected in a corner through 103, and the low-voltage side windings ax1 and ax2 are connected in series through 204.

[0058] According to the above analysis, this capacity adjustment method is Dyn11 when the capacity is large, and Yyn0 when the capacity is small. Assume that the rated current of the transformer before the capacity adjustment in the circuit diagram is large, and the rated current of the high-voltage side of the transformer is I N1 , then because the high-voltage coil is angle-connected when the transformer has a large capacity, the actual current flowing through the high-voltage coil is The rated current of the low voltage side is I N2 , the low voltage side is star connected, and the current flowing through the low voltage coil is also I N2 The load capacity and life of the capacity-adjusting transformer are measured under the critical conversion current. Therefore, when calculating, it is assumed that the critical conversion current I flows through the transformer in the capacity adjustment. LJ , also because the high-voltage coil is angle-connected when the transformer has a large capacity, the actual critical current flowing through the high-voltage coil is The actual critical current flowing through the high-voltage coil when the capacity is small is I LJ , the low voltage side is star connected, and the current flowing through the low voltage coil is kI LJ In addition, because the capacity ratio of this type of capacity-adjusting transformer is about 3:1, the rated current of the small capacity flowing through the transformer after capacity adjustment is about 1 / 3 of that of the large capacity, that is, the rated current on the high-voltage side is The actual current flowing through the high voltage coil is also The rated current flowing through the low voltage coil is Assume that the rated voltage of the high voltage side of the transformer is U N1 , the rated voltage of the low voltage side is U N2 , when the high voltage coil is corner connected, the terminal voltage is U N1 When the high voltage coil is connected in star connection, the terminal voltage is The coils on the low voltage side are all star-connected, so the terminal voltages are In addition, suppose the transition resistance value of the high-voltage side of the capacitor-adjusting switch is R, and the transition resistance value of the low-voltage side is r. Calculate the voltage and current of the main components of each capacitor-adjusting switch in the above (a)-(e) circuits. The results are shown in Table 1. Select the standard voltage and current above the absolute maximum value in Table 1 as the rated value. For example, if the calculated maximum absolute value of the current is 9.5A, the current value that is greater than 9.5A and is the standard current is 10A, and the rated current of the switch is selected as 10A.

[0059] Figure 3 The A-phase circuit diagram of the three-phase capacity-adjusting transformer of the high-low voltage coil series-parallel conversion type is shown in FIG. 1 , wherein the high voltage coil of the transformer is composed of windings AX1 and AX2, which can be connected in parallel through the capacity-adjusting switch contacts 303 and 305, and in series through 304; the low voltage coil is composed of windings ax1 and ax2, which can be connected in parallel through contacts 403 and 405, and in series through 404; the high voltage capacity-adjusting transition circuit is composed of a transition contact 301 in series with a high voltage transition resistor 302, and the low voltage capacity-adjusting transition circuit is composed of a transition contact 401 in series with a low voltage transition resistor 402. The principle of the transformer is: when the capacity is large, the high-voltage and low-voltage coil windings of the transformer are connected in parallel to form a Dyn11 connection, that is, the three-phase high-voltage coil is 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 a Dyn11 connection. When the main contact of the capacity adjustment changes from a large capacity state to a small capacity state, or from a small capacity to a large capacity, the transition circuit is connected to the circuit in advance and exits the circuit after the main contact is adjusted, thereby maintaining the power supply continuity during the transformer capacity adjustment process. The transition resistor limits the internal circulating current of the transformer during this process.

[0060] The transformer is connected in Dyn11 mode when it is large or small. The number of turns of the high and low voltage coils of the transformer becomes twice that of the large capacity after the large capacity is changed to the small capacity. The output voltage of the low voltage side remains unchanged. Since the voltage of the transformer coil per turn becomes lower than that of the large capacity after the small capacity is adjusted, The transformer core loss is reduced, thereby reducing the transformer no-load loss and achieving energy saving when the transformer is lightly loaded or no-loaded.

[0061] When calculating the parameters of the main components of the capacity adjustment switch, the circuit diagrams are established before the capacity adjustment when the transformer is large, during the capacity adjustment, and after the capacity adjustment to a small capacity. Figure 3(a) is the circuit diagram before the transformer is adjusted when the capacity is large. The transition contacts 301 and 302 are disconnected. The high-voltage windings AX1 and AX2 of the transformer are connected in parallel through 303 and 305. The low-voltage windings ax1 and ax2 are connected in parallel through 403 and 405. (b), (c), and (d) are the circuit diagrams of the transformer during capacity adjustment. (b) is the circuit diagram when the transition contacts 301 and 401 are closed and the main capacity adjustment contacts 303 and 305 connect the high-voltage windings AX1 and AX2 of the transformer in parallel. The low-voltage side 403 and 405 connect the low-voltage windings ax1 and ax2 of the transformer in parallel. (c) (d) is the circuit when the transition contacts 301 and 401 are closed and the main capacity-adjusting contacts 303, 304, 305, 403, 404, and 405 are all disconnected. (e) is the circuit diagram when the transformer is adjusted from large capacity to small capacity, the transition contacts 301 and 401 are disconnected, the transformer high-voltage winding AX is connected in series through 304, and the low-voltage side windings ax1 and ax2 are connected in series through 404.

[0062] From the above analysis, this type of capacity adjustment is Dyn11 connection when the capacity is large and small. Assume that the rated current of the transformer before the capacity adjustment in the circuit diagram flows through the large capacity, and assume that the rated current of the transformer high voltage side is I N1 , then because the high-voltage coil is angle-connected when the transformer has a large capacity, the actual current flowing through the high-voltage coil is Assume the rated current on the low voltage side is I N2 The low voltage side is star-connected and the current flowing through the low voltage coil is also I N2 ; Similarly, in the calculation, it is assumed that the critical conversion current I flows through the transformer in the capacity adjustment LJ , because the transformer high-voltage coil is angle-connected, the actual critical current flowing through the high-voltage coil is The low voltage side is star-connected, and the current flowing through the low voltage coil is kI LJ In addition, because the capacity ratio of this type of capacity-adjusting transformer is about 4:1, the rated current of the small capacity flowing through the transformer after capacity adjustment is about the rated current of the large capacity. That is, the rated current on the high voltage side is The actual current flowing through the high voltage coil is also The rated current flowing through the low voltage coil is Assume that the rated voltage of the high voltage side of the transformer is U N1 , the rated voltage of the low voltage side is U N2 , then the voltage at the corner terminal of the high voltage coil is U N1 , the low voltage side coil is star connected, so the terminal voltage is In addition, assuming that the transition resistance value of the high-voltage side of the capacitor-adjusting switch is R, and the transition resistance value of the low-voltage side is r, calculate the voltage and current of the main components of each capacitor-adjusting switch in the above (a)-(e) circuits. The results are shown in Table 2. Similarly, the standard voltage and current above the absolute maximum value in Table 2 are selected as the rated values.

[0063] Although the above process is calculated from the analysis of adjusting the transformer from large capacity to small capacity, the adjustment process from small capacity to large capacity is just the reverse process of the above process, and the conclusions of Table 1 and Table 2 are also applicable.

[0064] Traditional on-load voltage regulators need to change gear by gear from low gear to high gear or from high gear to low gear. For example, if you need to change from 5 gear to 1 gear, you must first change to 4, 3, and 2 gears before changing to 1 gear. Therefore, each time the voltage is adjusted, a gear is raised or lowered. The voltage between the transformer stages is a constant value, and its buck-boost circuit is fixed. There are fixed analysis methods, such as Appendix B of GB 10230.1, which can facilitate the selection and calculation of component parameters. Because the buck-boost circuit of the permanent magnet mechanism voltage regulator is significantly different from that of the on-load voltage regulator driven by a conventional motor, there is no typical component selection and calculation method.

[0065] The contacts of the permanent magnet mechanism voltage regulating selection switch can support the change from one arbitrary state to another arbitrary state, such as directly changing from 5th gear to 1st gear. Therefore, the voltage-boosting circuit of the permanent magnet mechanism voltage regulating switch is obviously different from the on-load voltage regulating switch driven by a conventional motor. The analysis and calculation method of this patent is as follows:

[0066] The three-phase circuits of the voltage regulator are the same, so only the A-phase circuit is analyzed below. Figure 4-Figure 8 As shown in the figure, a typical permanent magnet type voltage regulating switch is composed of voltage regulating selection switch contacts 501, 502, 503 driven by independent electromagnets and vacuum switching switch contacts 504 and 505, of which 504 is used for switching on and off the transformer main circuit, 505 is used for switching on and off the voltage regulating transition circuit, and 506 is a transition resistor. Figure 4-Figure 8 The transition circuit switch 505 is connected to the circuit in advance when the voltage regulation gear is changed and exits the circuit after the voltage regulation, thereby maintaining the power supply continuity during the transformer voltage regulation process, and the transition resistor 506 limits the internal circulation of the transformer during this process.

[0067] When calculating the parameters of the main components of the voltage regulating switch, the transformer is in a steady state with all gears. Figure 4-Figure 8 (a), and when all gears are incorporated into the transition circuit Figure 4-Figure 8 (b), and when all gears are disconnected from the main circuit Figure 4-Figure 8(c) respectively establish the circuit diagram. Assume that the transformer in the circuit diagram flows through the rated current IN, the voltage between adjacent voltage taps of the transformer is U, and the transition resistance is R. Calculate the above Figure 4-Figure 8 The voltage and current of each main component of the voltage regulating switch in the circuit (a)-(c) are calculated without further explanation. The results are shown in Table 3. The standard voltage and current above the absolute maximum value in Table 3 are also selected as the rated values.

[0068] Table 1 Main component parameters of high voltage star-angle conversion type capacity regulating switch

[0069]

[0070]

[0071] Table 2 Main component parameters of high voltage series-parallel conversion type capacity regulating switch

[0072]

[0073]

[0074] Table 3 Parameters of main components of voltage regulator switch

[0075]

[0076]

[0077] Embodiment 3, an embodiment of the present invention, provides a calculation method for selecting the main components of a transformer capacity-adjusting and voltage-adjusting switch, in order to verify the beneficial effects of the present invention.

[0078] The calculation method of the critical switching current in the calculation method provided by the present invention should calculate the two extreme cases where the load power factor is 1 or 0 respectively. The reason is that the transition resistance is approximately pure resistance, so the power factor is 1, and the load power factor carried by the transformer is uncertain. Therefore, the calculation results are actually vector addition and subtraction, which leads to the calculation results in Tables 1-3 are not the superposition of numerical values.

[0079] As shown in Table 3 When the load power factor is 1, I N and The vectors are in the same direction, and the absolute value of this item is the smallest; when the power factor is 0, I N and The vector directions differ by 90°. From vector calculation, we can know that this value has the largest absolute value. Under other power factor conditions, this value is between the above two conditions.

[0080] When calculating the parameters of the capacitance switch, the critical switching current I is used. LJ , assuming the transformer rated voltage U, rated large capacity and small capacity SND , S NX , no-load loss P at large and small capacity 0D , P 0X , load loss P for large and small capacity KD and P KX , critical switching current I LJ When the corresponding critical capacity is S LJ , because the transformer is under critical current, in small capacity and large capacity, the total loss of the transformer is equal, and the formula can be expressed as:

[0081]

[0082] The solution is expressed as:

[0083]

[0084] Also because:

[0085]

[0086] The critical switching current is obtained as:

[0087]

[0088] Another method is to multiply the transformer reactive power by the reactive economic equivalent of 0.1 as a kind of active power loss. Therefore, in addition to the no-load loss and load loss of the transformer, the reactive power is related to the no-load current and short-circuit impedance of the transformer. Assume that the no-load current I of the transformer is large and small. 0D % and I 0D %, short circuit impedance U KD % and U KX %, and the formula is:

[0089]

[0090] The critical switching current is obtained as:

[0091]

[0092] Example 4, reference Fig. 9 , which is an embodiment of the present invention, provides a main component selection calculation system for a transformer capacity regulating and voltage regulating switch, including a capacity regulating calculation module, a voltage regulating calculation module, and a selection module.

[0093] Among them, the capacity adjustment calculation module is used for the rated voltage and current selection calculation method of the high and low voltage main contacts, transition contacts and high and low transition resistances of the permanent magnet mechanism capacity adjustment switch; the voltage adjustment calculation module is used for the rated voltage and current selection calculation method of the gear selection contacts, switching main contacts, switching transition contacts and transition resistance of the permanent magnet mechanism voltage adjustment switch; the selection module is used for the selection method of the transition resistance wire diameter or line type.

[0094] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. 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, etc. Various media that can store program codes.

[0095] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0096] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0097] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc. It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limited. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

[0098] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention 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 invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for calculating the selection of the main components of a transformer capacity and voltage regulating switch, characterized in that: include: Calculation method for selecting rated voltage and current of high and low voltage main contacts, transition contacts and high and low transition resistances of permanent magnet mechanism capacity regulating switches; Calculation method for selecting the rated voltage and current of the position selection contact, switching main contact, switching transition contact and transition resistor of the permanent magnet mechanism voltage regulating switch; Method for selecting transition resistor wire diameter or wire type.

2. The method for calculating the selection of the main components of the transformer capacity and voltage regulating switch according to claim 1, characterized in that: The method for selecting and calculating the rated voltage and current of the high and low voltage main contacts, transition contacts and high and low transition resistances of the permanent magnet mechanism capacity-adjusting switch comprises establishing circuit diagrams before capacity adjustment, during capacity adjustment and after capacity adjustment to a small capacity when the transformer is large in capacity, assuming that the rated current of the transformer at a large capacity flows through the transformer before capacity adjustment, the critical conversion current flows through the transformer during capacity adjustment, and the rated current of the transformer at a small capacity flows through the transformer after capacity adjustment in the circuit diagram, calculating the voltage and current of each main component of the capacity-adjusting switch in the above circuit, and selecting the standard voltage and current above the maximum value as the rated value; The calculation method should calculate the two extreme cases of load power factor being 1 or 0 respectively.

3. The method for calculating the selection of the main components of the transformer capacity and voltage regulating switch according to claim 2, characterized in that: The rated voltage and current selection calculation method of the permanent magnet mechanism voltage regulating switch gear selection contact, switching main contact, switching transition contact and transition resistor includes establishing circuit diagrams when all gears of the transformer are in steady state, when all gears are incorporated into the transition circuit, and when all gears are disconnected from the main circuit, assuming that the rated current flows through the transformer in the circuit diagram, calculating the voltage and current of each main component of the capacity regulating switch in the above circuit, and selecting the standard voltage and current above the maximum absolute value of each as the rated value.

4. The method for calculating the selection of the main components of the transformer capacity and voltage regulating switch according to claim 3 is characterized in that: The capacity regulating switch includes a high-voltage side star-delta conversion type and a high-voltage side series-parallel conversion type; The circuit diagram of the high-voltage side star-delta conversion type in the capacity regulation includes three states: the transition contact is closed and the main capacity regulation contact connects the transformer high-voltage winding in delta to the low-voltage winding in parallel; the transition contact is closed and the main capacity regulation contact is all disconnected; the transition contact is closed and the main capacity regulation contact connects the transformer high-voltage winding in star to the low-voltage winding in series; The circuit diagram established in the capacity regulation of the high-voltage side series-parallel conversion type includes three states: the transition contact is closed and the main capacity regulation contacts are respectively connected in parallel with the high and low voltage windings of the transformer; the transition contact is closed and the main capacity regulation contacts are all disconnected; the transition contact is closed and the main capacity regulation contacts are respectively connected in series with the high and low voltage windings of the transformer.

5. The method for calculating the selection of the main components of the transformer capacity and voltage regulating switch according to claim 4, characterized in that: The method for selecting the wire diameter or line type of the transition resistor includes that the transition resistors of the capacitance regulating switch and the voltage regulating switch are made of nickel-chromium alloy Ni80Cr20 or iron-chromium-aluminum alloy Cr25Al5 or carbon fiber; When alloy is used for transition resistor, the wire diameter shall be selected according to the working current density of 60~90A / mm2; When using carbon fiber, the model is selected based on the working current being 15-20 times the long-term current that can pass through.

6. The method for calculating the selection of the main components of the transformer capacity and voltage regulating switch according to claim 5, characterized in that: The critical switching current includes calculating the critical switching current using the rated voltage, rated large capacity, rated small capacity, no-load loss and load loss of the transformer at large capacity and small capacity of the transformer, and is expressed as: Among them, I LJ represents the critical switching current, U represents the rated voltage of the transformer, S ND Indicates the rated maximum capacity of the capacity-regulating transformer, S NX Indicates the rated minimum capacity of the capacity-regulating transformer, P 0D Indicates the no-load loss of the transformer when it is large in capacity, P 0X Indicates the no-load loss of the transformer when the capacity is small, P KD Load loss when transformer is large capacity, P KX Load loss when the transformer is small capacity.

7. The method for calculating the selection of the main components of the transformer capacity and voltage regulating switch according to claim 6, characterized in that: The critical switching current also includes another calculation method, using the rated voltage of the transformer, the rated large capacity, the rated small capacity, the no-load loss and load loss of the transformer at large capacity and small capacity, the no-load current and short-circuit impedance of the transformer at large capacity and small capacity, to calculate the critical switching current, expressed as: Among them, I 0D % indicates the no-load current when the transformer is large capacity, I 0X % indicates the no-load current of the transformer when the capacity is small, U KD % indicates the short-circuit impedance of the transformer when it is large in capacity, U KX % represents the short-circuit impedance of the transformer when the capacity is small.

8. A system using the method for selecting and calculating the main components of a transformer capacity regulating and voltage regulating switch according to any one of claims 1 to 7, characterized in that: Including capacity adjustment calculation module, voltage adjustment calculation module, and selection module; The capacity adjustment calculation module is used for the rated voltage and current selection calculation method of the high and low voltage main contacts, transition contacts and high and low transition resistances of the permanent magnet mechanism capacity adjustment switch; The voltage regulation calculation module is used for the rated voltage and current selection calculation method of the permanent magnet mechanism voltage regulation switch gear selection contact, switching main contact, switching transition contact and transition resistance; The selection module is used for selecting the wire diameter or wire type of the transition resistor.

9. 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 calculation method for selecting the main components of the transformer capacity regulating and voltage regulating switch according to any one of claims 1 to 7 are implemented.

10. 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 calculation method for selecting the main components of the transformer capacity regulating and voltage regulating switch according to any one of claims 1 to 7 are implemented.

Images