阅读说明：本技术 一种用于直流断路器特性测试的恒流源装置 (Constant current source device for testing characteristics of direct current breaker ) 是由 袁俊国 张琳琳 李华 于 2020-12-03 设计创作，主要内容包括：本发明公开了一种用于直流断路器特性测试的恒流源装置,包括：直流发生器主回路,包括与交流电源连接的缓启单元、与缓启单元输出端连接的隔离变压器、与隔离变压器的输出端连接的整流器、与整流器的输出端连接的变换器、与变换器的输出端连接的滤波单元；输出电压控制单元,其输出端与直流断路器连接,其包括输出电压互感器、RC吸收单元、电压控制模块,其中,输出电压互感器与直流发生器主回路的输出端连接,RC吸收单元吸收回路剩余的能量,电压控制模块限制测试中直流断路器的触点电压。本发明无需设置引导波和阻抗预估,不仅可在宽范围内实现高精度直流恒流输出,毫秒级内达到稳态恒流设定值,而且对测试中的直流断路器也有很好的保护作用。(The invention discloses a constant current source device for testing the characteristics of a direct current breaker, which comprises: the direct current generator main loop comprises a slow start unit connected with an alternating current power supply, an isolation transformer connected with the output end of the slow start unit, a rectifier connected with the output end of the isolation transformer, a converter connected with the output end of the rectifier and a filtering unit connected with the output end of the converter; the output voltage control unit is connected with the direct current circuit breaker at the output end and comprises an output voltage transformer, an RC absorption unit and a voltage control module, wherein the output voltage transformer is connected with the output end of a main loop of the direct current generator, the RC absorption unit absorbs the residual energy of the loop, and the voltage control module limits the contact voltage of the direct current circuit breaker in the test. The invention does not need to set guide waves and impedance estimation, not only can realize high-precision direct current constant current output in a wide range and reach a steady-state constant current set value in millisecond level, but also has good protection effect on a direct current breaker in test.)

1. A constant current source device for testing the characteristics of a direct current breaker is characterized in that a steady-state constant current set value is achieved within a millisecond level, and the constant current source device comprises:

the direct current generator main loop comprises a slow start unit connected with an external alternating current power supply, an isolation transformer connected with the output end of the slow start unit, a rectifier connected with the output end of the isolation transformer, a converter connected with the output end of the rectifier and a filtering unit connected with the output end of the converter;

the output voltage control unit, its output is connected with the direct current circuit breaker who awaits measuring, output voltage control unit includes output voltage transformer, RC absorption unit, voltage control module, wherein, output voltage transformer's one end with the output of direct current generator major loop is connected, RC absorption unit is used for absorbing the remaining energy of return circuit, voltage control module is arranged in limiting the contact voltage of direct current circuit breaker in the characteristic test.

2. The constant current source device according to claim 1, further comprising a control unit, wherein a main control unit of the control unit is connected to the other end of the output voltage transformer of the output voltage control unit, the main control unit is further connected to the converter of the main circuit of the dc generator through a power conversion control interface unit, and the power conversion control interface unit is configured to adjust an output current of the converter.

3. The constant current source device according to claim 1, wherein the dc generator main circuit includes a plurality of group modules, each group module including a one-to-one converter and a filter unit, the plurality of group modules being arranged in parallel.

4. The constant current source device according to claim 2, wherein the main control unit performs PI regulation according to a preset current value, comprising: and calculating and outputting the PWM wave to control the parallel converter units in the plurality of group modules.

5. The constant current source device according to claim 2, wherein the control unit further comprises a measurement unit for sampling data of the output of the main circuit of the dc generator and/or the output voltage control unit, and a human-machine interface connected to the main control unit via the communication unit.

6. The constant current source device according to claim 2, wherein the main control unit comprises a DSP and an FPGA, and the main control unit is further connected to a slow start unit of the main loop of the dc generator.

7. The constant current source device according to claim 1, wherein the converter is a DC-DC conversion circuit.

8. The constant current source device according to claim 1, wherein the filter unit is an LC filter circuit.

9. The constant current source device according to claim 1, wherein the converter is a full bridge IGBT or MOSFET based DC-DC converter.

10. Use of a constant current source device according to any of claims 1-9 for testing the characteristics of a dc circuit breaker.

Technical Field

The invention relates to the field of constant current sources, in particular to a constant current source device for testing the characteristics of a direct current circuit breaker.

Background

The direct current circuit breaker is widely applied to the fields of electric power systems, rail transit and electric locomotives, new energy, ship electric power and the like, is an important electric product in relevant application fields, and needs to test the temperature rise, standard delay and instantaneous tripping characteristics of the circuit breaker in the research and development and production inspection processes of the direct current circuit breaker so as to ensure the product quality and reliability. Therefore, a large-current direct-current constant-current source device which has a large output range, fast dynamic response and a good protection effect on a direct-current circuit breaker in a test environment is needed.

At present, the existing large-current and wide-range direct current constant current source device is generally realized by a method of adding a voltage stabilizer and rectifying and filtering, small current guide waves are applied, the voltage and the current amplitude of an output end are sampled, the impedance of an output loop is estimated, after the estimated impedance is calculated, the output direct current voltage is adjusted through a closed-loop control system, and then the purpose of controlling the test current is achieved. Because the pilot wave needs to be preset, the output impedance needs to be calculated and calibrated for a long time, the detection efficiency is low, the impedance of different circuit breaker products has a certain range, the output voltage is low, and the sampling precision is not high, so that the requirement of high-precision output cannot be met.

Therefore, a direct current heavy current constant current device is needed, which solves the existing pilot wave and impedance estimation requirements, rapidly outputs a wide-range and high-precision test current, and has a direct current breaker test protection function.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a constant current source device for testing the characteristics of a direct current breaker, in particular to a high-precision direct current constant current source device which has wide requirements and can meet various characteristic test items, and a high-current direct current constant current device which has a protection function on the direct current breaker in the test, without using a guided wave and impedance pre-estimation mode, wherein the technical scheme is as follows:

the invention provides a constant current source device for testing the characteristics of a direct current breaker, which realizes that a steady-state constant current set value is reached within millisecond level, and comprises the following steps:

the direct current generator main loop comprises a slow start unit connected with an external alternating current power supply (such as a commercial power 220V/380V alternating current power supply), an isolation transformer connected with the output end of the slow start unit, a rectifier connected with the output end of the isolation transformer, a converter connected with the output end of the rectifier, and a filtering unit connected with the output end of the converter;

the output voltage control unit, its output is connected with the direct current circuit breaker who awaits measuring, output voltage control unit includes output voltage transformer, RC absorption unit, voltage control module, wherein, output voltage transformer's one end with the output of direct current generator major loop is connected, RC absorption unit is used for absorbing the remaining energy of return circuit, voltage control module is arranged in limiting the contact voltage of direct current circuit breaker in the characteristic test.

Further, the constant current source device provided by the invention further comprises a control unit, wherein a main control unit of the control unit is connected with the other end of the output voltage transformer of the output voltage control unit, the main control unit is also connected with a converter of the main circuit of the direct current generator through a power conversion control interface unit, and the power conversion control interface unit is used for adjusting the output current of the converter.

Further, the main circuit of the direct current generator comprises a plurality of group modules, each group module comprises a converter and a filter unit which are in one-to-one correspondence, and the group modules are arranged in parallel.

Further, the converter is a DC-DC conversion circuit, and the filter unit is an LC filter circuit.

Furthermore, the control unit also comprises a measuring unit and a human-computer interface, wherein the measuring unit is used for carrying out data sampling on the output and/or output voltage control unit of the main loop of the direct current generator, and the human-computer interface is connected with the main control unit through the communication unit.

Specifically, the main control unit comprises a DSP and an FPGA, and is further connected with a slow start unit of the main circuit of the direct current generator.

Preferably, the converter is a full-bridge DC-DC converter based on IGBTs or MOSFETs.

The invention has the following technical effects:

a. the constant current source device adopts direct closed-loop control of output current, does not need to set a guide wave and complicated impedance calculation, has high rise speed of test current, and successfully meets the requirement of second-level test quantity in practice;

b. on the basis of realizing the direct current breaker test performance, the safety of the direct current breaker in the test environment is guaranteed, and the working performance of the direct current breaker is not affected.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a constant current source device for testing characteristics of a dc circuit breaker according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of an output voltage control unit of the constant current source device provided by the embodiment of the present invention;

fig. 3 is a test waveform interface diagram of a dc circuit breaker to which the present constant current source device is applied according to an embodiment of the present invention.

Detailed Description

In order to make the technical solutions of the present invention better understood and more clearly understood by those skilled in the art, the technical solutions of the embodiments of the present invention will be described below in detail and completely with reference to the accompanying drawings. It should be noted that the implementations not shown or described in the drawings are in a form known to those of ordinary skill in the art. Additionally, while exemplifications of parameters including particular values may be provided herein, it is to be understood that the parameters need not be exactly equal to the respective values, but may be approximated to the respective values within acceptable error margins or design constraints. It is to be understood that the described embodiments are merely exemplary of a portion of the invention and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. In addition, the terms "comprises" and "comprising," and any variations thereof, in the description and claims of this invention, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In an embodiment of the present invention, a constant current source device for testing characteristics of a dc circuit breaker is provided to achieve a steady-state constant current set value within a millisecond range, as shown in fig. 1, the constant current source device includes a main loop of a dc generator, an output voltage control unit, and a control unit, and specifically includes the following components:

as shown in fig. 1, the main circuit of the dc generator includes a slow start unit, an isolation transformer, a rectifier, a converter, and a filtering unit, which are connected in sequence, that is, the slow start unit is connected to an external ac power supply, an output terminal of the slow start unit is connected to the isolation transformer, an output terminal of the isolation transformer is connected to the rectifier, an output terminal of the rectifier is connected to the converter, and an output terminal of the converter is connected to the filtering unit; specifically, the converter is a DC-DC conversion circuit, the converter is preferably an IGBT-based DC-DC full-bridge converter, and the filter unit is an LC filter circuit. It should be noted that the IGBTs in the converter may also be partially or fully replaced by other controllable switching devices, such as MOSFETs, transistors, etc.

As shown in fig. 2, an output end of the output voltage control unit is connected to the dc circuit breaker to be tested, the output voltage control unit includes an output voltage transformer, an RC absorbing unit, and a voltage control module, wherein one end of the output voltage transformer is connected to an output end of the main circuit of the dc generator, the RC absorbing unit is configured to absorb the remaining energy in the main circuit, and the voltage control module is configured to limit a contact voltage of the dc circuit breaker in the characteristic test.

As shown in fig. 1, the main control unit of the control unit is connected to the other end of the output voltage transformer of the output voltage control unit, and the main control unit is further connected to the converter of the dc generator main circuit through the power conversion control interface unit, specifically, the main control unit includes a DSP and an FPGA, and the main control unit is further connected to the slow start unit of the dc generator main circuit. The power conversion control interface unit is used for adjusting the output current of the converter; in an embodiment of the present invention, the control unit further includes a measurement unit and a human-machine interface, the measurement unit is configured to sample data of the output of the dc generator main loop and/or the output voltage control unit, and the human-machine interface is connected to the main control unit through the communication unit.

In one embodiment of the present invention, as shown in fig. 1, the main circuit of the dc generator includes a plurality of group modules, each group module includes a one-to-one converter and a filter unit, and the plurality of group modules are arranged in parallel. In this embodiment, the main control unit performs PI adjustment according to a preset current value, calculates an output PWM wave to control the converter units connected in parallel in the plurality of group modules, and adjusts the output current of the converter units connected in parallel in the plurality of groups. For the setting of the output current in a wide range, the present embodiment adopts a multi-stage filtering and sampling manner, so as to enhance the current output capability of the multi-module parallel converter unit and improve the accuracy of the output current. Because the direct current output control mode is adopted, the guide wave setting and the complex impedance calculation are not needed, the dynamic response of the output current is fast, and the millisecond-level reaching of the set value current can be realized in the whole output current range. The constant current source device of the embodiment is applied to the characteristic test of the direct current breaker, the corresponding test waveform is shown in fig. 3, wherein the first line is the current flowing through the direct current breaker, and the second line is the terminal voltage at two ends of the direct current breaker, as can be seen from fig. 3, the rising speed of the direct current test current is fast, the set value of 2000A (and below) can be reached within 4ms (1 ms for each unit on the abscissa), the highest precision of the output current is realized within 0.5%, and no guide wave and complex impedance calculation are needed to be set. In addition, as can be seen from experiments, the required time for the present example to output a steady-state constant current of 300A (and below) is about 1ms (within 2 ms); the constant current source device is used for outputting the steady-state constant current within the range of 2000A-4000A, and the required time is 6-7 ms, so that the constant current source device can achieve the steady-state constant current set value within a wide output current range in millisecond level, namely, the output of the steady-state constant current of 4000A or below within 10 ms.

As shown in fig. 2, one end of the output voltage control unit is connected in parallel with the output terminal, and the other end is connected with the main control unit, when the output current reaches the instantaneous trip current of the measured dc circuit breaker, the impedance of the contacts of the circuit breaker gradually rises in the trip process, and then the voltage at the two ends of the contacts rises, so that in the process of dropping the trip current, the accumulated energy in the circuit breaker can cause great damage to the contact surface of the contacts, especially a small circuit breaker. The constant current source device is used for testing the characteristics of the direct current circuit breaker, the voltages at two ends of the contacts of the circuit breaker in the characteristic testing process are detected, when the voltages reach a set value, the output voltage control unit is immediately triggered, the voltage of the contacts is limited to a lower value, the current flowing through the circuit breaker is reduced, the residual energy consumed by a return circuit is absorbed by using the RC, the contacts in the instantaneous tripping characteristic testing process are effectively protected, and the working characteristics of the circuit breaker after testing are not influenced.

The invention also claims to protect the application of the constant current source device in the characteristic test of the direct current circuit breaker, namely, the constant current source device is used as a power supply source for the characteristic test of the direct current circuit breaker, namely, a characteristic test system of the direct current circuit breaker is claimed, and the constant current source device is used as the power supply source of the test system to provide the constant current reaching the steady state within the second level.

In summary, through the above arrangement, the constant current source device for testing characteristics of the dc circuit breaker of the embodiment adopts direct closed-loop control of output current, so that it is not necessary to set pilot waves and estimate impedance, thereby improving the testing accuracy and efficiency, not only realizing high-accuracy dc constant current output in a wide range, satisfying the target of reaching a steady-state constant current set value in less than 4ms, but also having good protection effect on the dc circuit breaker in a testing environment.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.