System for testing grid-side short circuit of current-controllable converter powered by direct-current source

Abstract

The utility model discloses a grid-side short-circuit test system of a current-controllable converter powered by a direct-current source. In the current-controllable converter machine-grid side short circuit test system powered by the direct current source, the machine side of a tested converter is connected to a second three-phase reactor to simulate a motor, the grid side of the tested converter is connected to the second three-phase reactor to simulate a power grid, and the tested converter adopts an open-loop wave-generating current loading mode. The current under the test condition is loaded under the control of the upper computer, and then the short circuit test is carried out, so that short circuit fault simulation can be realized in the operation loading process of the current transformer, more comprehensive performance test can be carried out on the current transformer, and the protection capability of the current transformer when the short circuit occurs in the operation period can be truly reflected; moreover, the grid side of the tested converter is not directly connected to the motor and the power grid, so that the influence of the short circuit of the converter on the motor and the power grid can be eliminated, and the protection capability of the converter during the short circuit in the operation period can be truly reflected under the condition that the motor is not damaged and the power grid is not influenced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the short circuit test technical field of inverter, especially to a current controllable inverter machine network side short circuit test system of direct current source power supply. BACKGROUND

[0002] The short circuit test of wind power converter is mainly applied to the related field of inverter short circuit test technology in new energy industry, and for this kind of limit test working condition of inverter, it has been a kind of test mode with higher cost and greater risk in test means all the time, and there is great limitation, that is, it cannot simulate the short circuit working condition of real scene, and the main reason is that: 1, the laboratory motor resource is limited, and the generator is expensive; 2, the inverter is still in the short circuit test stage, and its protection ability is still uncertain; 3, the protection ability of short circuit test inverter in the test stage is uncertain, and then the risk of motor damage caused by testing under the condition of connecting generator to simulate actual short circuit situation is too great.

[0003] Based on the above consideration, the short circuit test of inverter is carried out in the open loop wave emission condition at present, and the machine side interphase short circuit and the machine side phase to ground short circuit, this kind of test method can reflect the protection ability of inverter short circuit to a certain extent, but there is still great difference between the test mode and the real inverter short circuit, and the inverter is in the stage of not loading when short circuit, therefore, the limit working condition of inverter is not enough, and it is difficult to simulate the real situation.

[0004] In summary, the existing inverter short circuit test method has the problem of not being able to truly reflect the protection ability of inverter when short circuit occurs during operation, and when the inverter machine network side short circuit test is carried out, there is also the problem of damaging the motor and affecting the power grid. SUMMARY

[0005] The technical problem to be solved by the utility model lies in providing a kind of current controllable inverter machine network side short circuit test system of direct current source power supply, which can truly reflect the protection ability of inverter when short circuit occurs during operation without damaging the motor and affecting the power grid.

[0006] To solve the above technical problem, the utility model adopts the technical scheme as follows:

[0007] A DC power supply current controllable converter machine network side short circuit test system, comprising: a measured converter, comprising a machine side power module and a network side power module, the machine side power module and the network side power module are connected through a DC bus; a DC power supply device, the input end of which is connected with the power grid, and the output end of which is connected with the DC bus of the measured converter; an electric stress acquisition module, which is connected with the machine side power module and the network side power module respectively, and is used for acquiring the electric stress of the machine side power module and the network side power module; a network side short circuit test device, which is connected to the network side of the measured converter, and is used for simulating the power grid, the network side short circuit test device comprises a first three-phase reactor, a first inter-phase circuit breaker and a first phase-ground circuit breaker, the first three-phase reactor is connected with the network side power module in three phases, the first inter-phase circuit breaker is connected between two phases of the connecting circuit between the network side power module and the first three-phase reactor, one end of the first phase-ground circuit breaker is connected with one phase of the connecting circuit between the network side power module and the first three-phase reactor, and the other end of the first phase-ground circuit breaker is grounded; a machine side short circuit test device, which is connected to the machine side of the measured converter, and is used for simulating the motor, the machine side short circuit test device comprises a second three-phase reactor, a second inter-phase circuit breaker and a second phase-ground circuit breaker, the second three-phase reactor is connected with the machine side power module in three phases, the second inter-phase circuit breaker is connected between two phases of the connecting circuit between the machine side power module and the second three-phase reactor, one end of the second phase-ground circuit breaker is connected with one phase of the connecting circuit between the machine side power module and the second three-phase reactor, and the other end of the second phase-ground circuit breaker is grounded; and a host computer, which is connected with the measured converter, the first inter-phase circuit breaker, the first phase-ground circuit breaker, the second inter-phase circuit breaker and the second phase-ground circuit breaker respectively.

[0008] Preferably, the DC power supply current controllable converter machine network side short circuit test system comprises an IO relay module, and the host computer is connected with the first inter-phase circuit breaker, the first phase-ground circuit breaker, the second inter-phase circuit breaker and the second phase-ground circuit breaker through the IO relay module.

[0009] Preferably, the DC power supply device comprises a power module, which converts the alternating current input from the power grid into direct current to supply power to the DC bus of the measured converter.

[0010] Preferably, the DC power supply device further comprises a first contactor and a first soft start circuit, the input end of the power module is connected with the power grid through the first contactor, one end of the first soft start circuit is connected with the output end of the power module, and the other end of the first soft start circuit is connected with the network side input end of the first contactor.

[0011] Preferably, the DC power supply device further comprises a safety fuse, which is connected in series between the power module and the power grid.

[0012] Preferably, the measured converter further comprises a machine-side inductor and a grid-side inductor, the grid-side inductor being connected between the grid-side power module and the grid-side short-circuit testing device, and the machine-side inductor being connected between the machine-side power module and the machine-side short-circuit testing device.

[0013] Preferably, a fuse is further connected in series between the grid-side power module and the grid-side short-circuit testing device.

[0014] Preferably, the measured converter further comprises a second contactor and a second soft-start circuit, the grid-side inductor is connected to the grid-side short-circuit testing device through the second contactor, one end of the second soft-start circuit is connected to a DC bus of the measured converter, and the other end of the second soft-start circuit is connected to a grid-side input end of the second contactor.

[0015] Preferably, a capacitor is connected between any two phases of the grid-side power module, and a resistor and a capacitor are connected in series between any two phases of the machine-side power module.

[0016] Preferably, the grid voltage is used to supply power to the upper computer and the IO relay module after being transformed by a 220V power supply transformer.

[0017] The current-controllable converter machine-grid side short-circuit testing system powered by the DC source can simulate a motor by connecting the machine side of the measured converter to the second three-phase reactor and simulate a power grid by connecting the grid side of the measured converter to the second three-phase reactor. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a circuit diagram of the current-controllable converter machine-grid side short-circuit testing system powered by the DC source in an embodiment of the utility model.

[0019] Marked as follows:

[0020] 1-direct current power supply device, 2-measured converter, 3-grid side short circuit test device, 4-machine side short circuit test device, 5-electric stress collection module, 6-upper computer, 7-IO relay module, 8-power grid, 9-220V power supply transformer, 11-power module, 21-grid side power module, 22-machine side power module, L1-grid side inductor, L2-machine side inductor, L3-first three-phase reactor, L4-second three-phase reactor, S1-first phase-to-phase circuit breaker, S2-first phase-to-ground circuit breaker, S3-second phase-to-phase circuit breaker, S4-second phase-to-ground circuit breaker, Q1-first contactor, Q2-second contactor, Q3-third contactor, Q4-fourth contactor, Q5-fifth contactor. DETAILED DESCRIPTION

[0021] In order to enable those ordinary skilled in the art to more clearly understand the purpose, technical scheme and advantages of the utility model, the utility model will be further described below in combination with the drawings and examples.

[0022] As Figure 1 shown, in an embodiment of the utility model, the direct current source power supply current controllable converter grid side and machine side short circuit test system includes a direct current power supply device 1, a measured converter 2, a grid side short circuit test device 3, a machine side short circuit test device 4, an electric stress collection module 5 and an upper computer 6.

[0023] The measured converter 20 comprises a machine-side power module 22 and a network-side power module 21 which are connected through a DC bus; the input end of the DC power supply device 1 is connected with the power grid 8, and the output end is connected with the DC bus of the measured converter 2; the electric stress collection module 5 is connected with the machine-side power module 22 and the network-side power module 21 respectively, and is used for collecting the electric stress of the machine-side power module 22 and the network-side power module 21; the network-side short-circuit test device 3 is connected to the network side of the measured converter 2, and is used for simulating the power grid 8; the network-side short-circuit test device 3 comprises a first three-phase reactor L3, a first inter-phase circuit breaker S1 and a first phase-to-ground circuit breaker S2; the first three-phase reactor L3 is connected with the network-side power module 21 in three phases; the first inter-phase circuit breaker S1 is connected between two phases of the connecting circuit between the network-side power module 21 and the first three-phase reactor L3; one end of the first phase-to-ground circuit breaker S2 is connected with one phase of the connecting circuit between the network-side power module 21 and the first three-phase reactor L3; and the other end of the first phase-to-ground circuit breaker S2 is grounded; the machine-side short-circuit test device 4 is connected to the machine side of the measured converter 2, and is used for simulating the motor; the machine-side short-circuit test device 4 comprises a second three-phase reactor L4, a second inter-phase circuit breaker S3 and a second phase-to-ground circuit breaker S4; the second three-phase reactor L4 is connected with the machine-side power module 22 in three phases; the second inter-phase circuit breaker S3 is connected between two phases of the connecting circuit between the machine-side power module 22 and the second three-phase reactor L4; one end of the second phase-to-ground circuit breaker S4 is connected with one phase of the connecting circuit between the machine-side power module 22 and the second three-phase reactor L4; and the other end of the second phase-to-ground circuit breaker S4 is grounded; and the upper computer 6 is connected with the measured converter 2, the first inter-phase circuit breaker S1, the first phase-to-ground circuit breaker S2, the second inter-phase circuit breaker S3 and the second phase-to-ground circuit breaker S4 respectively.

[0024] The upper computer 6 of the utility model as a total control, the whole converter machine network side short-circuit test process is: first DC power supply device 1 starts machine, for the DC bus power supply of measured converter 2, the upper computer 6 controls measured converter 2 and gradually loads current to the current value under test working condition, then after measured converter 2 runs stably, the upper computer 6 controls measured converter machine side and / or network side and carries out phase-to-phase short-circuit or phase-to-ground short-circuit, simultaneously, the upper computer 6 detects the converter response situation under measured converter machine side and / or network side short-circuit through electric stress collection module 5.

[0025] When controlling a short circuit on the generator side of the converter under test, the host computer 6 first selects between phases or between phases and ground according to the user-defined instructions, and then outputs corresponding instructions to control the corresponding circuit breaker (second phase-to-phase circuit breaker S3 or second phase-to-ground circuit breaker S4) in the generator side short circuit test device 4 to close, thereby controlling the generator side short circuit or between phases and ground of the converter under test to simulate the generator side short circuit test; when controlling a short circuit on the grid side of the converter under test, the host computer 6 first selects between phases or between phases and ground according to the user-defined instructions, and then outputs corresponding instructions to control the corresponding circuit breaker (first phase-to-phase circuit breaker S1 or first phase-to-ground circuit breaker S2) in the grid side short circuit test device 3 to close, thereby controlling the grid side short circuit or between phases and ground of the converter under test to simulate the grid side short circuit test.

[0026] The DC-powered, current-controllable converter short-circuit test system provided in this embodiment simulates a motor by connecting the tested converter 2 to the second and third-phase reactors on the machine side and the power grid by connecting it to the second and third-phase reactors on the grid side. The tested converter 2 uses an open-loop current loading method, and under the control of the host computer 6, the current is gradually loaded to the current value under the test conditions before the short-circuit test is performed. This allows for the simulation of short-circuit faults during the converter's operation and loading process, enabling a more comprehensive performance test of the converter and thus accurately reflecting the converter's protection capability during short circuits. Furthermore, since the tested converter 2 is not directly connected to the motor and the power grid on the machine side, the impact of the converter's short circuit on the motor and the power grid can be eliminated. Therefore, the system accurately reflects the converter's protection capability during short circuits without damaging the motor or affecting the power grid.

[0027] In some embodiments of this utility model, the DC-powered current-controllable converter grid-side short-circuit test system further includes an IO relay module 7. The host computer 6 is connected to the first phase-to-phase circuit breaker S1, the first phase-to-ground circuit breaker S2, the second phase-to-phase circuit breaker S3, and the second phase-to-ground circuit breaker S3 via the IO relay module 7. The voltage of the power grid 8 is transformed by the 220V power supply transformer 9 and then used to power the host computer 6 and the IO relay module 7.

[0028] Since short-circuit testing of converters is an extreme condition test, the testing process is extremely dangerous. In this embodiment, the host computer 6 first sends a short-circuit command, and then the corresponding circuit breaker is closed through the IO relay module 7 to achieve short-circuit control of the grid side of the converter under test 2. The isolation control through the IO relay module 7 provides higher safety and ensures the safety of operators under extreme test conditions.

[0029] See you again Figure 1In a preferred embodiment of the present invention, the DC power supply device 1 includes a power module 11, which is composed of multiple power semiconductor switching devices for converting AC power input from the power grid into DC power to supply power to the DC bus of the converter under test 2.

[0030] The DC power supply device 1 further includes a first contactor Q and a first soft start circuit. The input terminal of the power module 11 is connected to the power grid 8 through the first contactor Q1. One end of the first soft start circuit is connected to the output terminal of the power module 11, and the other end of the first soft start circuit is connected to the grid-side input terminal of the first contactor Q1. The DC power supply device 1 also includes a fuse, which is connected in series between the power module 11 and the power grid 8.

[0031] See you again Figure 1 In a preferred embodiment of this utility model, the converter under test 2 further includes a machine-side inductor L2 and a grid-side inductor L1. The grid-side inductor L1 is connected between the grid-side power module 21 and the grid-side short-circuit test device 3, and the machine-side inductor L2 is connected between the machine-side power module 22 and the machine-side short-circuit test device 4. A fuse is also connected in series between the grid-side power module 21 and the grid-side short-circuit test device 3.

[0032] The converter under test 2 also includes a second contactor Q2 and a second soft-start circuit. The grid-side inductor L1 is connected to the grid-side short-circuit test device 3 through the second contactor Q2. One end of the second soft-start circuit is connected to the DC bus of the converter under test 2, and the other end is connected to the grid-side input terminal of the second contactor Q2. A capacitor is connected between any two phases on the grid side of the grid-side power module 21, and a resistor and a capacitor are connected in series between any two phases on the machine side of the machine-side power module 22.

[0033] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Those skilled in the art can make various equivalent changes and improvements based on the above embodiments. All equivalent changes or modifications made within the scope of the claims should fall within the protection scope of the present utility model.

Claims

1. A short-circuit test system for the grid side of a current-controllable converter powered by a DC source, characterized in that, include: A converter under test includes a generator-side power module and a grid-side power module, which are connected via a DC bus. A DC power supply device, whose input terminal is connected to the power grid and whose output terminal is connected to the DC bus of the converter under test; An electrical stress acquisition module is connected to the machine-side power module and the grid-side power module respectively, and is used to acquire the electrical stress of the machine-side power module and the grid-side power module. A grid-side short-circuit test device is connected to the grid side of the converter under test to simulate the power grid. The grid-side short-circuit test device includes a first three-phase reactor, a first phase-to-phase circuit breaker, and a first phase-to-ground circuit breaker. The first three-phase reactor is connected to the grid-side power module in three phases. The first phase-to-phase circuit breaker is connected between two phases of the connection circuit between the grid-side power module and the first three-phase reactor. One end of the first phase-to-ground circuit breaker is connected to one phase of the connection circuit between the grid-side power module and the first three-phase reactor, and the other end of the first phase-to-ground circuit breaker is grounded. A machine-side short-circuit test device is connected to the machine side of the converter under test to simulate a motor. The machine-side short-circuit test device includes a second three-phase reactor, a second phase-to-phase circuit breaker, and a second phase-to-ground circuit breaker. The second three-phase reactor is connected to the three phases of the machine-side power module. The second phase-to-phase circuit breaker is connected between two phases of the connection circuit between the machine-side power module and the second three-phase reactor. One end of the second phase-to-ground circuit breaker is connected to one phase of the connection circuit between the machine-side power module and the second three-phase reactor, and the other end of the second phase-to-ground circuit breaker is grounded. A host computer is connected to the converter under test, the first phase-to-phase circuit breaker, the first phase-to-ground circuit breaker, the second phase-to-phase circuit breaker, and the second phase-to-ground circuit breaker.

2. The DC-powered, current-controllable converter grid-side short-circuit test system as described in claim 1, characterized in that, The system includes an I / O relay module, through which the host computer is connected to the first phase-to-phase circuit breaker, the first phase-to-ground circuit breaker, the second phase-to-phase circuit breaker, and the second phase-to-ground circuit breaker, respectively.

3. The DC-powered, current-controllable converter grid-side short-circuit test system as described in claim 2, characterized in that, The DC power supply device includes a power module that converts AC power input from the power grid into DC power to supply power to the DC bus of the converter under test.

4. The DC-powered, current-controllable converter grid-side short-circuit test system as described in claim 3, characterized in that, The DC power supply device further includes a first contactor and a first soft start circuit. The input terminal of the power module is connected to the power grid through the first contactor. One end of the first soft start circuit is connected to the output terminal of the power module, and the other end of the first soft start circuit is connected to the grid-side input terminal of the first contactor.

5. The DC-powered, current-controllable converter grid-side short-circuit test system as described in claim 4, characterized in that, The DC power supply device also includes a fuse, which is connected in series between the power module and the power grid.

6. The DC-powered, current-controllable converter grid-side short-circuit test system as described in claim 2, characterized in that, The converter under test also includes a machine-side inductor and a grid-side inductor. The grid-side inductor is connected between the grid-side power module and the grid-side short-circuit test device, and the machine-side inductor is connected between the machine-side power module and the machine-side short-circuit test device.

7. The DC-powered, current-controllable converter grid-side short-circuit test system as described in claim 6, characterized in that, A fuse is also connected in series between the grid-side power module and the grid-side short-circuit test device.

8. The DC-powered current-controllable converter grid-side short-circuit test system as described in claim 6, characterized in that, The converter under test also includes a second contactor and a second soft start circuit. The grid-side inductor is connected to the grid-side short-circuit test device through the second contactor. One end of the second soft start circuit is connected to the DC bus of the converter under test, and the other end of the second soft start circuit is connected to the grid-side input terminal of the second contactor.

9. The DC-powered, current-controllable converter grid-side short-circuit test system as described in claim 8, characterized in that, A capacitor is connected between any two phases on the grid side of the power module, and a resistor and a capacitor are connected in series between any two phases on the machine side of the power module.

10. The DC-powered current-controllable converter grid-side short-circuit test system as described in any one of claims 2-9, characterized in that, The mains voltage is transformed by a 220V power supply transformer and then used to power the host computer and the IO relay module.

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