Method for verifying coordination protection of direct-current power distribution system

Abstract

The invention discloses a method for verifying coordination protection of a direct-current power distribution system. The method for verifying the coordination protection of the direct-current power distribution system comprises the following steps: S1, connecting an external charging circuit: the external charging circuit comprises an alternating-current bus, the alternating-current bus is connected with a charging power supply main switch, the charging power supply main switch is connected with a voltage regulator, and the voltage regulator is connected to an inverter power supply screen of the direct-current power distribution system; s2, performing a branch short-circuit test; and S3, performing a DC bus short circuit test. The problems that in the prior art, energy consumption is large, and large damage risks are caused to equipment are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a method for verifying coordinated protection of a direct current distribution system. Background Art

[0002] like Figure 1 As shown in FIG. 1 , it is a schematic diagram of a DC power distribution system. When verifying the reliability of the coordinated protection of the DC power distribution system, an external DC power source, such as a generator set 1 or a battery power source 2, is often used as a power source, and then an external DC short-circuit switch is used to simulate various short-circuit test items. However, using a generator set or a battery power source as a power source for testing not only consumes a lot of energy, but also poses a risk of causing significant damage to the equipment. Summary of the invention

[0003] The purpose of the present invention is to provide a method for verifying coordinated protection of a DC power distribution system with low energy consumption and avoiding major damage to equipment in view of the deficiencies in the prior art.

[0004] To achieve the above object, the technical solution adopted by the method for verifying coordinated protection of a DC power distribution system of the present invention is:

[0005] A method for verifying coordinated protection of a DC power distribution system comprises the following steps:

[0006] S1. Connecting an external charging circuit: The external charging circuit includes an AC busbar, the AC busbar is connected to a charging power main switch, the charging power main switch is connected to a voltage regulator, and the voltage regulator is connected to an inverter power panel of a DC power distribution system;

[0007] S2, branch short circuit test:

[0008] S21, select any branch and connect a DC short-circuit switch between the fuse and the inverter of the branch;

[0009] S22. Precharge the DC bus: confirm that all branch switches on the DC power distribution system are in the closed state, confirm that the generator precharge switch and the connected DC short-circuit switch are in the open state, close the charging power supply main switch, and when the DC bus voltage meets the test conditions, disconnect the charging power supply main switch;

[0010] S23, close the connected DC short-circuit switch;

[0011] S24. Check whether the qualified basis of branch short-circuit test is met;

[0012] S25, repeat S21-S24, and complete the short-circuit test of the remaining branches one by one;

[0013] S3, DC bus short circuit test:

[0014] S31, connect a DC shorting switch at any point on the DC busbar on one side of the bus tie switch;

[0015] S32. Precharge the DC bus: confirm that all branch switches on the DC power distribution system are in the closed state, confirm that the generator precharge switch and the connected DC short-circuit switch are in the open state, close the charging power supply main switch, and when the DC bus voltage meets the test conditions, disconnect the charging power supply main switch;

[0016] S33, close the connected DC short-circuit switch;

[0017] S34. Check whether the qualification criteria for the DC bus short-circuit test are met;

[0018] S35. Repeat S31-S34 to complete the short-circuit test of the DC bus on the other side of the bus tie switch.

[0019] Preferably, the qualified basis of the branch short-circuit test is that the fuse on the short-circuit test branch is blown; the short-circuit current I flowing through the fuse on the non-short-circuit test branch 2 t does not exceed the pre-arcing current I of the branch fuse 2 t; The inverter on the short-circuit test branch is not damaged and can continue to be put into use after replacing the fuse on the short-circuit test branch.

[0020] Preferably, the qualification basis of the DC bus short-circuit test is that the bus tie switch automatically trips, the fuses on the branches connected to the DC bus on the non-short-circuit test side are intact, and the short-circuit current I flowing through the fuses on the branches connected to the DC bus on the non-short-circuit test side is 2 t does not exceed the pre-arcing current I of the branch fuse 2 t.

[0021] Preferably, the test condition is 800-1000V.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The DC bus is charged by an external charging circuit, and the electricity is stored in the capacitors in the inverters on each branch, replacing the generator set or battery power supply, which can not only reduce energy consumption, but also greatly reduce the destructive power to the equipment during the short-circuit test due to the limited storage capacity of the capacitor, making the short-circuit test safer and more reliable. In addition, the generator set or battery power supply does not participate in the short-circuit test, which can reduce the number of participants, shorten the short-circuit test cycle, and improve work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of a DC power distribution system;

[0025] Figure 2is a flow chart of a method for verifying coordinated protection of a DC power distribution system according to the present invention;

[0026] Figure 3 It is the working principle diagram of the external charging circuit;

[0027] Figure 4 This is the schematic diagram of the branch short circuit test;

[0028] Figure 5 This is the schematic diagram of the DC bus short-circuit test;

[0029] Figure 6 This is a screenshot of the oscilloscope waveform during the test;

[0030] Figure 7 It is the waveform diagram of short-circuit current and DC bus voltage;

[0031] Figure 8 is the fault branch current waveform and current I 2 t;

[0032] Fig. 9 is the fault-proximal branch current and the current I 2 t;

[0033] Fig.10 is the fault remote branch current and current I 2 t.

[0034] Among them, 1 is the generator set, 2 is the battery power supply, 3 is the AC bus, 4 is the charging power main switch, 5 is the voltage regulator, 6 is the inverter power panel, 7 is the 1# main propulsion motor panel, 8 is the DC bus, 9 is the fuse, 10 is the inverter, 11 is the DC short-circuit switch, and 12 is the bus tie switch. DETAILED DESCRIPTION

[0035] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0036] like Figure 2-10 As shown, a method for verifying coordinated protection of a DC power distribution system comprises the following steps:

[0037] S1. Connecting an external charging circuit: The external charging circuit includes an AC bus 3, the AC bus is connected to a charging power main switch 4, the charging power main switch is connected to a voltage regulator 5, and the voltage regulator is connected to an inverter power panel 6 of a DC power distribution system;

[0038] S2, branch short circuit test:

[0039] S21, select the left branch connecting the 1# main propulsion motor panel 7 and the DC bus 8, and connect the DC short-circuit switch 11 between the fuse 9 and the inverter 10 of the branch;

[0040] S22. Precharge the DC bus: confirm that all branch switches on the DC power distribution system are in the closed state, confirm that the generator precharge switch and the connected DC short-circuit switch are in the open state, close the charging power supply main switch, and measure the DC bus voltage. When it meets the test conditions, the experimental condition is 850V, disconnect the charging power supply main switch;

[0041] S23, close the connected DC short-circuit switch;

[0042] S24. Check whether the qualified basis of the branch short-circuit test is met. The qualified basis of the branch short-circuit test is: the fuse on the short-circuit test branch (fault branch) is blown; the short-circuit current I flowing through the fuse on the non-short-circuit test branch (non-fault branch) is 2 t does not exceed the pre-arcing current I of the branch fuse 2 t; The inverter on the short-circuit test branch is not damaged and can continue to be put into use after replacing the fuse on the short-circuit test branch;

[0043] S25, repeat S21-S24, and complete the short-circuit test of the remaining branches one by one;

[0044] S3, DC bus short circuit test:

[0045] S31, connect a DC shorting switch at point C on the DC busbar on the left side of the bus tie switch 12;

[0046] S32. Precharge the DC bus: confirm that all branch switches on the DC power distribution system are in the closed state, confirm that the generator precharge switch and the connected DC short-circuit switch are in the open state, close the charging power supply main switch, and measure the DC bus voltage. When it meets the test conditions, the experimental condition is 900V, disconnect the charging power supply main switch;

[0047] S33, close the connected DC short-circuit switch;

[0048] S34. Check whether the DC bus short-circuit test meets the qualification criteria. The qualification criteria for the DC bus short-circuit test are that the bus tie switch automatically trips, the fuses on the branches connected to the DC bus on the right side (non-short-circuit test side, also known as the non-fault side) are intact, and the short-circuit current I flowing through the fuses on the branches connected to the DC bus on the right side is 2 t does not exceed the pre-arcing current I of the branch fuse 2 t;

[0049] S35. Repeat S31-S34 to complete the short-circuit test of the DC bus on the right side of the bus tie switch.

[0050] The present invention charges the DC bus by using an external charging circuit on the basis of the existing DC power distribution system, and the electricity is stored in the capacitor in the frequency converter of each branch, replacing the generator set or battery power supply, which can reduce energy consumption. Since the storage capacity of the capacitor for electricity is limited, it can also greatly reduce the destructive force on the equipment during the short-circuit test, making the short-circuit test safer and more reliable. In addition, the generator set or battery power supply does not participate in the short-circuit test, which can reduce the number of test personnel, shorten the short-circuit test cycle, and improve work efficiency.

Claims

1. A method for verifying coordinated protection of a DC power distribution system, comprising the following steps: S1. Connecting an external charging circuit: The external charging circuit includes an AC busbar, the AC busbar is connected to a charging power main switch, the charging power main switch is connected to a voltage regulator, and the voltage regulator is connected to an inverter power panel of a DC power distribution system; S2, branch short circuit test: S21, select any branch and connect a DC short-circuit switch between the fuse and the inverter of the branch; S22. Precharge the DC bus: confirm that all branch switches on the DC power distribution system are in the closed state, confirm that the generator precharge switch and the connected DC short-circuit switch are in the open state, close the charging power supply main switch, and when the DC bus voltage meets the test conditions, disconnect the charging power supply main switch; S23, close the connected DC short-circuit switch; S24. Check whether the qualified basis of branch short-circuit test is met; S25, repeat S21-S24, and complete the short-circuit test of the remaining branches one by one; S3, DC bus short circuit test: S31, connect a DC shorting switch at any point on the DC busbar on one side of the bus tie switch; S32. Precharge the DC bus: confirm that all branch switches on the DC power distribution system are in the closed state, confirm that the generator precharge switch and the connected DC short-circuit switch are in the open state, close the charging power supply main switch, and when the DC bus voltage meets the test conditions, disconnect the charging power supply main switch; S33, close the connected DC short-circuit switch; S34. Check whether the qualification criteria for the DC bus short-circuit test are met; S35. Repeat S31-S34 to complete the short-circuit test of the DC bus on the other side of the bus tie switch.

2. The method for verifying coordinated protection of a DC power distribution system according to claim 1, characterized in that: The qualified basis for the branch short-circuit test is that the fuse on the short-circuit test branch is blown; the short-circuit current I flowing through the fuse on the non-short-circuit test branch 2 t does not exceed the pre-arcing current I of the branch fuse 2 t; The inverter on the short-circuit test branch is not damaged and can continue to be put into use after replacing the fuse on the short-circuit test branch.

3. The method for verifying coordinated protection of a DC power distribution system according to claim 1, characterized in that: The qualified basis of the DC bus short-circuit test is that the bus tie switch automatically trips, the fuses on the branches connected to the DC bus on the non-short-circuit test side are intact, and the short-circuit current I flowing through the fuses on the branches connected to the DC bus on the non-short-circuit test side is 2 t does not exceed the pre-arcing current I of the branch fuse 2 t.

4. The method for verifying coordinated protection of a DC power distribution system according to claim 1, characterized in that: The test conditions are 800-1000V.

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