阅读说明：本技术 供电装置 (Power supply device ) 是由 廖姗姗 何东升 刘顺桂 钟士朝 范竞敏 欧志平 唐拥林 于 2020-12-28 设计创作，主要内容包括：本申请涉及一种供电装置。所述装置包括：变频电源、电容器单元、控制单元和测量单元,变频电源的输出端与电容器单元的输入端连接,电容器单元的输出端与待测变压器的输入端连接,测量单元的输入端与待测变压器连接,主控单元分别与电容器单元和测量单元连接,测量单元,获取待测变压器的运行参数,主控单元,根据运行参数控制电容器单元对变频电源的输出电压进行升压操作。采用本供电装置具有体积小、易携带至待测变压器应用现场、成本低的优点。(The present application relates to a power supply device. The device comprises: the output end of the variable frequency power supply is connected with the input end of the capacitor unit, the output end of the capacitor unit is connected with the input end of the transformer to be tested, the input end of the measuring unit is connected with the transformer to be tested, the main control unit is respectively connected with the capacitor unit and the measuring unit, the measuring unit acquires the operating parameters of the transformer to be tested, and the main control unit controls the capacitor unit to perform boosting operation on the output voltage of the variable frequency power supply according to the operating parameters. The power supply device has the advantages of small volume, easy carrying to the application field of the transformer to be tested and low cost.)

1. A power supply apparatus, characterized in that the apparatus comprises: the device comprises a variable frequency power supply, a capacitor unit, a main control unit and a measuring unit; the output end of the variable frequency power supply is connected with the input end of the capacitor unit, and the output end of the capacitor unit is connected with the input end of the transformer to be tested; the input end of the measuring unit is connected with the transformer to be measured, and the main control unit is respectively connected with the capacitor unit and the measuring unit;

the measuring unit is used for acquiring the operating parameters of the transformer to be measured;

and the main control unit is used for controlling the capacitor unit to carry out boosting operation on the output voltage of the variable frequency power supply according to the operation parameters.

2. The apparatus of claim 1, wherein the capacitor unit comprises three capacitor sub-units, the capacitor sub-units comprising a series capacitance bank comprising at least one first capacitance path;

the input end of the series capacitor bank is connected with one phase line output end of the variable frequency power supply, and the output end of the series capacitor bank is connected with the input end of the transformer to be tested.

3. The apparatus of claim 2, wherein the series capacitor bank comprises a plurality of first capacitor paths connected in parallel, the first capacitor paths comprising at least one switch and at least one capacitor, and two ends of the switch are respectively connected to two ends of the corresponding capacitor.

4. The device according to any one of claims 2 or 3, wherein the main control unit is configured to control the series capacitor bank to perform a boosting operation on the output voltage of the variable frequency power supply according to the operation parameter.

5. The apparatus according to claim 4, wherein the main control unit is configured to determine a target capacitor in the series capacitor bank according to the operation parameter, and control an open/close state of each switch in the series capacitor bank according to the target capacitor, so as to implement a boost operation on the output voltage of the variable frequency power supply through the target capacitor.

6. The apparatus of claim 5, wherein the operating parameter comprises an output voltage of the transformer under test;

and the main control unit is used for determining the target capacitor according to the voltage difference between the output voltage of the transformer to be tested and the output voltage of the variable frequency power supply.

7. The apparatus of claim 2, wherein the capacitor sub-unit further comprises a parallel capacitance bank comprising at least one second capacitive path;

the input end of the parallel capacitor bank is respectively connected with the output end of the variable frequency power supply and the input end of the series capacitor bank, and the output end of the parallel capacitor bank is grounded.

8. The apparatus of claim 7, wherein the parallel capacitor bank comprises a plurality of second capacitor paths connected in parallel, the second capacitor paths comprising a switch and at least one capacitor, the switch is connected to the output terminal of the variable frequency power supply and one end of the at least one capacitor, respectively, and the other end of the at least one capacitor is grounded.

9. The device of claim 7, wherein the main control unit is further configured to control the parallel capacitor bank to perform reactive compensation according to the operation parameter.

10. The apparatus of claim 9, wherein the operating parameter comprises an internal resistance of the transformer under test;

and the main control unit is used for controlling the parallel capacitor bank to perform reactive compensation according to the internal resistance of the transformer to be tested.

Technical Field

The application relates to the technical field of power transformer testing, in particular to a power supply device.

Background

With rapid development of national economy and pace acceleration of power grid construction, the scale of the power grid is continuously enlarged, the short-circuit capacity is increasingly improved, and higher requirements are provided for safe and reliable operation of the power transformer. The power transformer has the advantages that the quality of equipment insulation is gradually reduced and the structure is gradually damaged in the high-temperature operation process due to the long-term action of factors such as an electric field, temperature, mechanical force, the surrounding environment and the like, so that the temperature rise test needs to be carried out on the transformer, and the temperature rise test is used as an index of the safety and reliability of the power transformer.

In the conventional technology, a power transformer needs to be transported to a third-party testing mechanism or a fixed place for testing, and a power supply device in a laboratory or the fixed place is used for supplying power to the power transformer for temperature rise testing.

However, the power supply device and the test system used for the temperature rise test at present have the problems of large volume, heavy mass, difficulty in moving and the like.

Disclosure of Invention

Therefore, in order to solve the above technical problems, a power supply device which is small in size, convenient to carry and applicable to testing in a power transformer application field is needed.

A power supply apparatus, the apparatus comprising:

the device comprises a variable frequency power supply, a capacitor unit, a main control unit and a measuring unit; the output end of the variable frequency power supply is connected with the input end of the capacitor unit, and the output end of the capacitor unit is connected with the input end of the transformer to be tested; the input end of the measuring unit is connected with the transformer to be measured, and the main control unit is respectively connected with the capacitor unit and the measuring unit;

the measuring unit is used for acquiring the operating parameters of the transformer to be measured;

and the main control unit is used for controlling the capacitor unit to carry out boosting operation on the output voltage of the variable-frequency power supply according to the operation parameters.

In one embodiment, the capacitor unit comprises three capacitor sub-units, the capacitor sub-units comprising a series capacitance bank comprising at least one first capacitance path;

the input end of the series capacitor bank is connected with one phase line output end of the variable frequency power supply, and the output end of the series capacitor bank is connected with the input end of the transformer to be tested.

In one embodiment, the series capacitor bank comprises a plurality of first capacitor paths connected in parallel, each first capacitor path comprises at least one switch and at least one capacitor, and two ends of each switch are respectively connected with two ends of the corresponding capacitor.

In one embodiment, the main control unit is used for controlling the series capacitor bank to perform boosting operation on the output voltage of the variable frequency power supply according to the operation parameters.

In one embodiment, the main control unit is configured to determine a target capacitor in the series capacitor bank according to the operation parameter, and control an open/close state of each switch in the series capacitor bank according to the target capacitor, so as to implement a voltage boosting operation on the output voltage of the variable frequency power supply through the target capacitor.

In one embodiment, the operating parameter includes an output voltage of the transformer under test;

and the main control unit is used for determining the target capacitor according to the voltage difference between the output voltage of the transformer to be tested and the output voltage of the variable frequency power supply.

In one embodiment, the capacitor subunit further comprises a parallel capacitance bank comprising at least one second capacitance path;

the input end of the parallel capacitor bank is respectively connected with the output end of the variable frequency power supply and the input end of the series capacitor bank, and the output end of the parallel capacitor bank is grounded.

In one embodiment, the parallel capacitor bank comprises a plurality of second capacitor paths connected in parallel, each second capacitor path comprises a switch and at least one capacitor, the switches are respectively connected with the output end of the variable frequency power supply and one end of the at least one capacitor, and the other end of the at least one capacitor is grounded.

In one embodiment, the main control unit is further configured to control the parallel capacitor bank to perform reactive compensation according to the operation parameter.

In one embodiment, the operating parameter comprises the internal resistance of the transformer to be tested;

and the main control unit is used for controlling the parallel capacitor bank to perform reactive compensation according to the internal resistance of the transformer to be detected.

The above power supply device includes: the output end of the variable frequency power supply is connected with the input end of the capacitor unit, the output end of the capacitor unit is connected with the input end of the transformer to be tested, the input end of the measuring unit is connected with the transformer to be tested, the main control unit is respectively connected with the capacitor unit and the measuring unit, the measuring unit acquires the operating parameters of the transformer to be tested, and the main control unit controls the capacitor unit to perform boosting operation on the output voltage of the variable frequency power supply according to the operating parameters. Because variable frequency power supply compares in the power supply that carries out the temperature rise test in laboratory or fixed place, small, portable, simultaneously, through main control unit control and variable frequency power supply connection capacitor unit and can realize the operation of stepping up, for carrying out the temperature rise test and providing the test power supply, need not to choose for use the higher switch tube of cost to regulate and control, consequently, adopt this power supply unit have small, easily carry to the transformer application site that awaits measuring, advantage with low costs.

Drawings

FIG. 1 is a block diagram of a power supply apparatus according to an embodiment;

FIG. 2 is a block diagram of a power supply device in one embodiment;

FIG. 3 is a block diagram of a power supply device in one embodiment;

FIG. 4 is a block diagram of a power supply device in one embodiment;

FIG. 5 is a block diagram of a power supply device in one embodiment;

fig. 6 is a block diagram showing the configuration of a power supply device in one embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

The numbering of the components as such, for example "first", "second", etc., in this application is used solely to distinguish between the objects depicted and not to imply any order or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings). In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present application and for simplicity in description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be considered as limiting the present application.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

The quality of the transformer is gradually reduced and the structure of the transformer is gradually damaged in the high-temperature operation process due to factors such as an electric field, temperature, mechanical force, surrounding environment and the like. Therefore, before the transformer is put into use formally and after the transformer is used for a certain time, temperature rise tests are required to be carried out on the transformer to detect whether the transformer can be used normally or not. In the prior art, when the transformer is subjected to the temperature rise test, the transformer needs to be transported to a third-party laboratory for testing, but when the transformer is transported to the laboratory for the temperature rise test, the problems of long transportation time, low efficiency, limitation of warehouse capacity, construction time node control and incapability of disassembling after the transformer is too large in size and mounted exist, and the temperature rise test of all transformers cannot be performed. The main reason that the temperature rise tests of the transformer are carried out in a third-party laboratory in the prior art is that the requirement on the capacity of the power supply device is high during the temperature rise tests, and the capacity of the power supply device determines the size of the power supply device, so that the power supply device for carrying out the temperature rise tests has the problems of overlarge size, heavy weight, difficulty in carrying and incapability of carrying out tests on the application site of the transformer. Based on this, the following embodiments of the present application provide a relay device that can solve the above technical problems. The following specifically describes examples of the present application.

Fig. 1 is a block diagram of a power supply device according to an embodiment of the present application. The power supply device includes: the device comprises a variable frequency power supply 11, a capacitor unit 12, a main control unit 13 and a measuring unit 14; the output end of the variable frequency power supply 11 is connected with the input end of the capacitor unit 12, and the output end of the capacitor unit 12 is connected with the input end of the transformer 15 to be tested; the input end of the measuring unit 14 is connected with a transformer 15 to be measured, and the main control unit 13 is respectively connected with the capacitor unit 12 and the measuring unit 14;

the measuring unit 14 is used for acquiring the operation parameters of the transformer to be measured;

and the main control unit 13 is used for controlling the capacitor unit to perform voltage boosting operation on the output voltage of the variable-frequency power supply according to the operation parameters.

In the embodiment of the present application, an input end of a variable frequency power supply is connected to a mains supply provided by a power grid, wherein the mains supply may be a 380V alternating current signal, and the variable frequency power supply outputs a sine wave signal to an input end of the capacitor unit through AC → DC → AC conversion of the received 380V alternating current signal of the mains supply, wherein an output frequency and an output voltage are adjustable within a certain range. Alternatively, the variable frequency power supply may be a linear amplification type variable frequency power supply, or may be an SPWM switching type variable frequency power supply, which is not limited herein.

The input end of the capacitor unit is connected with the output end of the variable frequency power supply, the output end of the capacitor unit is connected with the input end of the transformer to be tested, the capacitor unit is used for increasing the voltage value of alternating current input by the variable frequency power supply, and optionally, the capacitor unit can also provide reactive compensation, so that the power compensation factor is infinitely close to 1. Alternatively, the capacitor unit may include 3 capacitor subunits, wherein the variable frequency power supply is a three-phase output terminal, and therefore, three capacitor subunits are required to be respectively connected with the three-phase output terminal of the variable frequency power supply. The capacitor subunit can be formed by connecting a plurality of series capacitor groups in parallel; the capacitor unit may further include a plurality of series capacitor banks and a plurality of parallel capacitor banks, which is not limited herein. Alternatively, the capacitor may be a ceramic Capacitor (CT), a polyester Capacitor (CL), a monolithic capacitor (CC), an electrolytic Capacitor (CD), a mica Capacitor (CY), a tantalum Capacitor (CA), etc., which is not limited herein.

The input end of the measuring unit is connected with the output end of the transformer to be measured, the output end of the measuring unit is connected with the main control unit, and the measuring unit is used for collecting the operating parameters of the transformer to be measured and transmitting the operating parameters of the transformer to be measured to the main control unit. The measuring unit may include a voltage sensor, a current sensor, a resistance sensor, a temperature sensor, and the like, which are not limited herein, and the operating parameter of the transformer to be measured may be a voltage signal, a current signal, a power value, an internal resistance, a temperature, and the like, which are not limited herein.

The input end of the main control unit is connected with the output end of the measuring unit, the output end of the main control unit is connected with the capacitor unit, and the capacitor unit is used for analyzing and calculating the operation parameters of the transformer to be measured, which are acquired by the measuring unit, to obtain a voltage value to be increased, and providing a corresponding voltage value according to the voltage value. Optionally, the main control Unit may be implemented by a Micro Control Unit (MCU) chip, a dsp (digital Signal processing) chip, a Field Programmable Gate Array (FPGA) chip, or the like, which is not limited in the embodiment of the present application.

In this embodiment, the power supply device includes: the output end of the variable frequency power supply is connected with the input end of the capacitor unit, the output end of the capacitor unit is connected with the input end of the transformer to be tested, the input end of the measuring unit is connected with the transformer to be tested, the main control unit is respectively connected with the capacitor unit and the measuring unit, the measuring unit acquires the operating parameters of the transformer to be tested, and the main control unit controls the capacitor unit to perform boosting operation on the output voltage of the variable frequency power supply according to the operating parameters. Because variable frequency power supply compares in the power supply who carries out the temperature rise test in laboratory or fixed place, power density is high, small, portable, simultaneously, through main control unit control and variable frequency power supply connection capacitor unit and can realize the operation of stepping up, for carrying out the temperature rise test and providing the test power supply, need not to choose for use the higher switch tube of cost for carrying out, consequently, adopt this power supply unit have small, easily carry to the transformer application site that awaits measuring, advantage with low costs.

The foregoing embodiment describes a power supply device, which includes a plurality of units, where a capacitor unit is a core unit of the power supply device, and the capacitor unit may boost an output voltage of a variable frequency power supply and provide power compensation for a transformer to be tested, and now further describes a capacitor unit according to an embodiment, in an embodiment, as shown in fig. 2, a capacitor unit 12 includes three capacitor sub-units 21, the capacitor sub-units 21 include a series capacitor group 211, and the series capacitor group 211 includes at least one first capacitor path 2111; the input end of the series capacitor bank 211 is connected with one phase line output end of the variable frequency power supply 11, and the output end of the series capacitor bank 211 is connected with the input end of the transformer 15 to be tested.

In the embodiment of the present application, the capacitor unit includes three capacitor subunits, wherein an input terminal of each capacitor subunit is connected to the three-phase line of the output terminal of the variable frequency power supply, and an output terminal of each capacitor subunit is connected to the input terminal of the transformer to be tested. Each capacitor subunit includes a series capacitor group, the series capacitor group may include one first capacitor path or a plurality of first capacitor paths, and the plurality of capacitor paths may be connected in parallel. The first capacitor path refers to a path composed of a plurality of switches and capacitors, where each switch is connected in parallel to two ends of one capacitor, or one switch is connected in parallel to two ends of a circuit composed of a plurality of capacitors in series, which is not limited herein. Wherein, a plurality of first capacitance paths can be included in the series capacitance group.

Optionally, when the power supply device operates to supply power to the transformer to be tested, if the switch in the capacitor unit is opened, the capacitor is charged, and when the switch is closed, the capacitor is discharged, so as to increase the voltage value output by the variable frequency power supply.

In this embodiment, the capacitor unit includes three capacitor subunits, each capacitor subunit includes a series capacitor bank, the series capacitor bank includes at least one first capacitor path, an input end of the series capacitor bank is connected to one phase line output end of the variable frequency power supply, and an output end of the series capacitor bank is connected to an input end of the transformer to be tested. Because when the capacitor is connected in series in the circuit, the capacitor can realize the charge-discharge function, the capacitor is charged when the switch in the capacitor unit is switched off, when the switch is switched on, the circuit can be discharged, so that the voltage is boosted, the output voltage of the variable frequency power supply is boosted by simply connecting the capacitor in series, the power supply which is large in size, high in cost and low in capacity is not needed for supplying power to the transformer to be tested, and the size of the power supply device is reduced.

The above embodiments describe the series capacitor bank in the capacitor unit, and first further describe the first capacitor path in the series capacitor bank. In one embodiment, as shown in fig. 3, the series capacitor bank 31 includes a plurality of first capacitor paths 311 connected in parallel, each capacitor path includes at least one switch and at least one capacitor, and two ends of the switch are respectively connected to two ends of the corresponding capacitor.

In this embodiment, the series capacitor bank includes a plurality of first capacitor paths connected in parallel, each first capacitor path includes at least one switch and at least one capacitor, and two ends of each switch are respectively connected to two ends of the corresponding capacitor. The first capacitor path includes at least one switch and at least one capacitor, the first capacitor path may include a switch a and a capacitor C, two ends of the switch a respectively correspond to two ends of the capacitor C, or the first capacitor path may include: the circuit comprises a switch B and three capacitors E, F, G, wherein the capacitor E, the capacitor F and the capacitor G are sequentially connected in series, one end of the switch B is connected with the input end of the capacitor E, and the other end of the switch B is connected with the output end of the capacitor G; the two switches 1 and 2 may also correspond to four capacitors a, b, c, and d, where the capacitors a, b, c, and d are sequentially connected in series, two ends of the switch 1 are connected to two ends of the capacitor a, one end of the switch 2 is connected to the input end of the capacitor b, and the other end of the switch 2 is connected to the output end of the capacitor d, which is not limited herein.

In this embodiment, the series capacitor bank includes a plurality of first capacitor paths connected in parallel, each capacitor path includes at least one switch and at least one capacitor, and two ends of each switch are respectively connected to two ends of the corresponding capacitor. Because the series capacitor group formed by the first capacitor access in parallel connection can store electric quantity with different capacities through capacitors with different quantities, the possibility of boosting the output voltage of the variable frequency power supply is provided, and a certain voltage value can be provided under different conditions, so that the test condition of constant power can be maintained when the temperature rise test is carried out on the transformer to be tested.

The above embodiments describe a capacitor unit of a power supply device, and when the capacitor unit is used to boost an output voltage of a variable frequency power supply, a main control unit is required to control an internal switch of the capacitor unit to open and close.

In the embodiment of the present application, the operation parameters refer to output voltage, output current, and the like of the transformer to be tested when the transformer to be tested is subjected to a temperature rise test. The input end of the main control unit is connected with the output end of the measuring unit, the measuring unit transmits the output voltage to the main control unit after collecting the output voltage of the transformer to be measured, the main control unit analyzes and calculates to obtain a voltage value needing boosting, and the switch in the first capacitor access capable of providing the required voltage value in the capacitor unit is controlled to be switched on and off according to the voltage value needing boosting, so that the capacitor is charged and discharged, and corresponding voltage is provided for boosting. For example, if the voltage received by the main control unit at the time of the transformer to be tested is 500V and the voltage needs to be increased to 600V, the switch in the first capacitance path providing 100V voltage may be closed in the capacitor unit, so that the capacitance in the first capacitance path is charged and discharged, thereby increasing the voltage outputting 100V and maintaining the input voltage of the transformer to be tested at 600V.

In this embodiment, the main control unit controls the series capacitor bank to perform the boosting operation on the output voltage of the variable frequency power supply according to the operation parameters, and after the main control unit performs analysis and calculation according to the operation parameters, the voltage value required to be boosted can be obtained, and the switch inside the series capacitor bank is controlled, and the capacitor full of charge is discharged by using the charge-discharge principle of the capacitor, so that the purpose of boosting the output voltage of the variable frequency power supply is achieved, the input voltage of the transformer to be tested can be always maintained at a constant voltage, and the national standard GB/T1094.2-2013 part 2 of the power transformer is satisfied: the constant voltage state required by the temperature rise of the liquid immersed transformer improves the accuracy of the temperature rise test.

In an embodiment, the main control unit is configured to determine a target capacitor in the series capacitor group according to an operation parameter, and control an open/close state of each switch in the series capacitor group according to the target capacitor, so as to implement a boosting operation on an output voltage of the variable frequency power supply through the target capacitor.

In the embodiment of the present application, the target capacitor is a capacitor that needs to be charged and discharged to boost the output voltage of the variable frequency power supply. The capacitors in the series capacitor bank can be consistent in capacity or inconsistent in capacity, so that the capacitors with different capacities or the capacitors with the same capacity need to be determined to be combined, different voltages can be provided, and meanwhile, the output of the variable frequency power supply can be regulated and controlled, so that the output voltage of the variable frequency power supply can be increased to the voltage required by the transformer to be tested. For example, the series capacitor bank may include 6 capacitors with the same capacity, which are respectively a capacitor q, a capacitor w, a capacitor e, a capacitor r, a capacitor t, and a capacitor y, where the 6 capacitors are sequentially connected in series, and two ends of each capacitor are connected in parallel to a switch, which is a switch z, a switch x, a switch c, a switch V, a switch b, and a switch n, in sequence, and each capacitor may provide a voltage of 50V during charging and discharging, and if the main control unit determines that the voltage value to be increased is 200V according to the output voltage of the transformer to be tested in the operation parameters, it is only necessary to control the switch z, the switch x, the switch c, and the switch V to be closed, or control the switch c, the switch V, the switch b, and the switch n to be closed, or control any 4 switches among the 6 switches to be closed, which is not limited herein. Through the operation, the voltage of 200V except the variable frequency power supply can be received for the transformer to be tested, namely, the voltage output by the variable frequency power supply is increased by 200V.

In this embodiment, the main control unit determines a target capacitor in the series capacitor bank according to the operation parameter, and controls the on/off state of each switch in the series capacitor bank according to the target capacitor, so as to implement the step-up operation on the output voltage of the variable frequency power supply through the target capacitor. Because the target capacitor can be controlled according to the real-time operation parameters through the main control unit, the output voltage of the variable frequency power supply is boosted, so that the stable output voltage can be always maintained when the transformer to be tested performs a temperature rise test, and the accuracy of the test is ensured.

The foregoing embodiment describes the control of the on/off state of each switch in the series capacitor bank by the main control unit, and when controlling the on/off state of each switch in the series capacitor bank, it is first necessary to determine a target capacitor corresponding to the switch, and how to determine the target capacitor is described with an embodiment in which the operating parameter includes an output voltage of the transformer to be tested;

and the main control unit is used for determining the target capacitor according to the voltage difference between the output voltage of the transformer to be tested and the output voltage of the variable frequency power supply.

In the embodiment of the present application, the operation parameter is an output voltage of the transformer to be tested. The main control unit performs subtraction according to the output voltage of the transformer to be tested and the output voltage of the variable frequency power supply to obtain a voltage value required to be increased, for example, the output voltage of the variable frequency power supply is 600V, if the output voltage of the transformer to be tested is 550V at the moment, the output voltage of the variable frequency power supply and the required voltage difference of the transformer to be tested, namely, the voltage difference of 50V, at the moment, if the series capacitor bank comprises two capacitors, the capacitor m can provide 30V voltage, the capacitor n can provide 50V voltage, a switch corresponding to the capacitor n is selected to be closed, and it is determined that the target capacitor is the capacitor n.

In this embodiment, the main control unit determines the target capacitance according to the voltage difference between the output voltage of the transformer to be tested and the output voltage of the variable frequency power supply, so that the voltage of the transformer to be tested can be ensured to be kept constant all the time in the test process, and the accuracy of the temperature rise test is improved.

The above embodiments have explained the series capacitance group of the power supply device, and in one embodiment, as shown in fig. 4, the capacitor sub-unit further includes a parallel capacitance group 41, and the parallel capacitance group 41 includes at least one second capacitance path 411;

the input end of the parallel capacitor bank 41 is connected to the output end of the variable frequency power supply 11 and the input end of the series capacitor bank 42, respectively, and the output end of the parallel capacitor bank 41 is grounded.

In this embodiment, the capacitor subunit further includes a parallel capacitance group, where the parallel capacitance group includes at least one second capacitance path, where the parallel capacitance group may include one second capacitance path or a plurality of second capacitance paths, and the plurality of second capacitances are connected in parallel, which is not limited herein. The input end of the parallel capacitor bank is respectively connected with the output end of the variable frequency power supply and the input end of the series capacitor bank, and the output end of the parallel capacitor bank is grounded. Optionally, the input end of the parallel capacitor bank may be further connected to the output end of the series capacitor bank and the input end of the transformer to be tested, and the output end of the parallel capacitor bank is grounded.

In this embodiment, the capacitor subunit further includes a parallel capacitor bank, where the parallel capacitor bank includes at least one second capacitor path, an input end of the parallel capacitor bank is connected to an output end of the variable frequency power supply and an input end of the series capacitor bank, respectively, and an output end of the parallel capacitor bank is grounded. Because the capacitor subunit also comprises the parallel capacitor group, the inductive impedance of the transformer to be tested can be neutralized by providing capacitive impedance, reactive compensation is carried out, the power compensation factor is close to 1, and the electric energy loss is reduced.

Based on the above embodiment, as shown in fig. 5, the parallel capacitor bank includes a plurality of second capacitor paths 51 connected in parallel, each second capacitor path includes a switch and at least one capacitor, the switches are respectively connected to the output terminal of the variable frequency power supply and one end of the at least one capacitor, and the other end of the at least one capacitor is grounded.

In this embodiment, the second capacitance path includes a switch and at least one capacitor, the switch is respectively connected to the output terminal of the variable frequency power supply and one end of the at least one capacitor, and the other end of the at least one capacitor is grounded; the second capacitor path may also include a switch and 2 capacitors, a capacitor H and a capacitor J, one end of the switch is connected to the output end of the variable frequency power supply, the other end of the switch is connected to one end of the capacitor H, the other end of the capacitor H is connected to one end of the capacitor J, and the other end of the capacitor J is grounded, which is not limited herein.

In one embodiment, the parallel capacitor bank comprises a plurality of second capacitor paths connected in parallel, each second capacitor path comprises a switch and at least one capacitor, the switches are respectively connected with the output end of the variable frequency power supply and one end of the at least one capacitor, and the other end of the at least one capacitor is grounded. Different reactive compensation is carried out to different degrees according to the internal resistance condition of the transformer to be tested by connecting different second capacitor paths in parallel, so that the energy loss is reduced.

In one embodiment, the main control unit is further configured to control the parallel capacitor bank to perform reactive compensation according to the operation parameter.

In the embodiment of the application, the operation parameter may be an internal resistance of the transformer to be tested, and the main control unit performs reactive compensation according to the internal resistance of the transformer to be tested as the operation parameter. The measuring unit collects the internal resistance value of the transformer to be measured, the internal resistance value is transmitted to the main control unit, the main control unit carries out analysis and calculation to obtain the capacitance number in the parallel capacitor bank required by reactive compensation, and a second capacitor access in the parallel capacitor bank is closed, so that the reactive compensation is realized. In an example, the internal resistance value of the transformer to be measured, which is acquired by the measurement unit, is 20 ohms, and at this time, the internal resistance value is inductive impedance, and the main control unit is required to control the conduction of the second capacitor paths in the parallel capacitor bank, so as to provide 20-ohm capacitive impedance, and if one second capacitor path can provide 10-ohm capacitive impedance, two second capacitor paths need to be selectively conducted, so that the implementation is achieved.

In this embodiment, the main control unit may also control the parallel capacitor bank to perform reactive compensation according to the operating parameters, where the power compensation factor is as close to 1 as possible, so as to reduce energy loss and improve the accuracy of the test.

To facilitate understanding of the skilled person, the transformer testing apparatus is now described with an embodiment, as shown in fig. 6, the power supply apparatus includes: a variable frequency power supply 61, a capacitor unit 62, a main control unit 63 and a measurement unit 64; the output end of the variable frequency power supply 61 is connected with the input end of the capacitor unit 62, and the output end of the capacitor unit 62 is connected with the input end of the transformer 65 to be tested; wherein capacitor unit 62 comprises three capacitor sub-units, a capacitor sub-unit comprising a series capacitance bank comprising at least one first capacitive path; the input end of the series capacitor bank is connected to one phase line output end of the variable frequency power supply 61, and the output end of the series capacitor bank is connected to the input end of the transformer to be measured 65. The series capacitor bank comprises a plurality of first capacitor paths connected in parallel, each first capacitor path comprises at least one switch and at least one capacitor, and two ends of each switch are respectively connected with two ends of the corresponding capacitor. The capacitor subunit further comprises a parallel capacitance bank comprising at least one second capacitive path; the input end of the parallel capacitor bank is respectively connected with the output end of the variable frequency power supply and the input end of the series capacitor bank, and the output end of the parallel capacitor bank is grounded. The parallel capacitor group comprises a plurality of second capacitor paths which are connected in parallel, each second capacitor path comprises a switch and at least one capacitor, the switches are respectively connected with the output end of the variable frequency power supply and one end of the at least one capacitor, and the other end of the at least one capacitor is grounded. The input end of the measuring unit 63 is connected with a transformer 65 to be measured, and the main control unit 64 is respectively connected with the capacitor unit 62 and the measuring unit 63;

the measuring unit 63 is used for acquiring the operation parameters of the transformer to be measured;

the main control unit 64 is used for controlling the capacitor unit to carry out boosting operation on the output voltage of the variable-frequency power supply according to the operation parameters; and the parallel capacitor bank is controlled to perform reactive compensation according to the operation parameters.

The components, connection relationships, and use processes of the parts in this embodiment may refer to the detailed description in the foregoing embodiments, and are not repeated herein.

In this embodiment, the power supply device includes: the output end of the variable frequency power supply is connected with the input end of the capacitor unit, the output end of the capacitor unit is connected with the input end of the transformer to be tested, the input end of the measuring unit is connected with the transformer to be tested, the main control unit is respectively connected with the capacitor unit and the measuring unit, the measuring unit acquires the operating parameters of the transformer to be tested, and the main control unit controls the capacitor unit to perform boosting operation on the output voltage of the variable frequency power supply according to the operating parameters. Because variable frequency power supply compares in the power supply that carries out the temperature rise test in laboratory or fixed place, small, portable, simultaneously, through main control unit control and variable frequency power supply connection capacitor unit and can realize the operation of stepping up, for carrying out the temperature rise test and providing test power supply, need not to choose for use the higher high withstand voltage value switch tube of cost to step up, consequently, adopt this power supply unit have small, easily carry to the transformer that awaits measuring and use on-the-spot, advantage with low costs.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.