Medium-voltage DC source

Abstract

The medium-voltage direct-current source comprises a three-phase power supply, a voltage regulator, a phase-shifting transformer and a rectifying circuit which are connected in sequence, and the rectifying circuit comprises a first rectifying circuit and a second rectifying circuit which are connected in series or in parallel. The phase-shifting transformer comprises a primary winding connected with the voltage regulator by adopting a star connection method, a first secondary winding adopting the star connection method and a second secondary winding adopting the delta connection method; three terminals of the first secondary winding are respectively connected between two rectifier diodes in the three rectifier diode groups of the first rectifier circuit; and three terminals of the second secondary winding are respectively connected between two rectifier diodes in the three rectifier diode groups of the second rectifier circuit. According to the medium-voltage direct-current source provided by the invention, a relatively stable direct-current pulse wave power supply can be output after the mains supply takes electricity, voltage regulation, phase shift and rectification are carried out, the output voltage can be regulated through the voltage regulator, and pulse wave output is increased by changing a series-parallel connection combination connection method of the power supply.

Description

Technical Field

[0001] The invention relates to a DC system insulation monitoring device, in particular to a medium voltage DC source. Background Art

[0002] An Insulation Monitoring Device (IMD) is a device specifically used to monitor the insulation resistance of power grids to ground in power systems. Traditionally, the insulation resistance we monitor mainly involves low-voltage AC and DC power grids such as AC380V, DC24V, and DC200V. However, with the development of power systems and technological advances, we are beginning to face the challenges of medium-voltage DC4000V power grids. The insulation monitoring measurement of this medium-voltage DC power grid is not only more technically difficult, but also has greater safety risks. This patent involves a medium-voltage DC source device that uses a neutral point grounding method, which is significantly different from the test device for low-voltage AC and DC power grids.

[0003] To meet this new measurement requirement, we cannot simply rely on previous test devices because they do not meet the special requirements of medium-voltage DC grids. Therefore, it is urgent to develop a new medium-voltage DC source to meet the special needs of medium-voltage DC grid insulation monitoring. Summary of the invention

[0004] In view of the above-mentioned deficiencies of the current test device, the present invention provides a medium voltage DC source, which can output a relatively stable DC pulse power supply after voltage regulation, phase shifting and rectification after taking power from the mains. In addition, the output voltage can be adjusted by a voltage regulator, and the pulse output can be increased by changing the series-parallel combination connection method of the power supply.

[0005] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0006] A medium voltage direct current source comprises a three-phase power supply, a voltage regulator connected to the three-phase power supply, a phase-shifting transformer connected to the voltage regulator, and a rectifier circuit, wherein the rectifier circuit is connected to the phase-shifting transformer, the rectifier circuit comprises a first rectifier circuit and a second rectifier circuit, the voltage regulator is configured to boost the three-phase power supply, the phase-shifting transformer comprises a primary winding, a first secondary winding and a second secondary winding, the voltage regulator is connected to the primary winding of the phase-shifting transformer, the primary winding adopts a star connection, the first secondary winding adopts a star connection, and the second secondary adopts a delta connection; three terminals of the first secondary winding are respectively connected between two rectifier diodes in three groups of rectifier diodes in the first rectifier circuit; three terminals of the second secondary winding are respectively connected between two rectifier diodes in three groups of rectifier diodes in the second rectifier circuit, and the first rectifier circuit and the second rectifier circuit are connected in series or in parallel.

[0007] According to one aspect of the present invention, the DC source is configured as a plurality of DC sources, a first rectifier circuit and a second rectifier circuit in the same DC source are connected in parallel, and rectifier circuits between the plurality of DC sources are connected in series and / or in parallel to form a 24-pulse rectifier DC source.

[0008] According to one aspect of the present invention, the DC source is configured as a plurality of DC sources, a first rectifier circuit and a second rectifier circuit in the same DC source are connected in series, and rectifier circuits between the plurality of DC sources are connected in series and / or in parallel to form a 12-pulse rectifier DC source.

[0009] According to one aspect of the present invention, it also includes a second grounding circuit, the connection terminal of the second grounding circuit is arranged between the first rectifier circuit and the second rectifier circuit, the second grounding circuit includes a grounding switch S1, one end of the grounding switch S1 is connected to the first rectifier circuit and the second rectifier circuit, the other end of the grounding switch S1 is connected to a grounding resistor, and the other end of the grounding resistor is grounded.

[0010] According to one aspect of the present invention, the grounding resistor includes a resistor R1, a resistor R2 and a resistor R3 connected in series in sequence.

[0011] According to one aspect of the present invention, the rectifier circuit is installed in a rectifier cabinet, and the resistor R3 is connected to the rectifier cabinet housing and grounded.

[0012] According to one aspect of the present invention, it further includes a plurality of grounding resistors to be measured, wherein the grounding resistors to be measured are arranged between the grounding resistor and the output end of the first rectifier circuit or the output end of the second rectifier circuit, and the other end of the grounding resistors to be measured is grounded.

[0013] According to one aspect of the present invention, it also includes multiple voltmeters, the two ends of the grounding resistance to be measured are connected to the voltmeters, the voltmeters are used to detect the voltage value of the resistance to be measured, and the voltmeters are configured to measure the voltage value between positive and ground, negative and ground, and / or between positive and negative poles.

[0014] According to one aspect of the present invention, it further comprises a power-on control switch, which is arranged between the three-phase power supply and the voltage regulator and is used to control the on and off of the three-phase power supply.

[0015] According to one aspect of the present invention, the three-phase power supply is provided with a distribution cabinet, and a first grounding circuit is provided in the distribution cabinet. The first grounding circuit is connected to the three-phase power supply. The first grounding circuit includes a resistor R0, one end of the resistor R0 is connected to the three-phase power supply, and the other end of the resistor R0 is grounded.

[0016] Advantages of the implementation of the present invention: After being powered by the mains, a relatively stable DC pulse power supply can be output after voltage regulation, phase shifting and rectification, which can meet the test requirements of the DC system insulation monitoring device for the medium-voltage DC source with neutral point grounding. The output of the pulse is changed by changing the series-parallel connection mode of the first rectifier circuit and the second rectifier circuit in the same DC source. By setting up multiple DC sources and changing the series-parallel connection mode of the rectifier circuits between the multiple DC sources, the output of the pulse is increased, a stable DC source output is formed, and the quality requirements of the power supply are improved. A medium-voltage DC source provided by the present invention can output a relatively stable DC pulse power supply after voltage regulation, phase shifting and rectification after being powered by the mains. The output voltage can be adjusted by a voltage regulator, and the pulse output can be increased by changing the series-parallel combination connection method of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic diagram of the manufacturing principle of a medium voltage DC source according to the present invention;

[0019] Figure 2 A schematic diagram of a medium voltage DC source test principle according to the present invention;

[0020] Figure 3 A schematic diagram of a simulation of 12-pulse rectification formed by multiple DC sources in a medium voltage DC source according to the present invention;

[0021] Figure 4 The present invention provides a schematic diagram of a 24-pulse rectification simulation for multiple DC sources in a medium voltage DC source.

[0022] The numbers in the figure are: 1, power distribution cabinet; 11, first grounding circuit; 2, power-on control switch; 3, voltage regulator; 4, phase-shifting transformer; 41, primary winding; 42, first secondary winding; 43, second secondary winding; 5, rectifier cabinet; 51, first rectifier circuit; 52, second rectifier circuit; 53, second grounding circuit. 100, DC source; 101, DC source A; 102, DC source B; 103, DC source C; 104, DC source D; 105, DC source E; 106, DC source F. DETAILED DESCRIPTION

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] like Figure 1 and Figure 2 As shown, a medium-voltage DC source is mainly used to test and verify the insulation monitoring device of a medium-voltage DC system, which includes a three-phase power supply, and the three-phase power supply is provided with a distribution cabinet 1, and the distribution cabinet 1 is a mains power distribution cabinet, and the distribution cabinet 1 is connected to an AC380V three-phase power supply, and a first grounding circuit 11 is provided in the distribution cabinet 1, and the first grounding circuit 11 includes a resistor R0, one end of the resistor R0 is connected to one end of the three-phase power supply, and the other end of the resistor R0 is grounded; the other end of the three-phase power supply is connected to a voltage regulator 3, and the voltage regulator 3 is configured to boost the three-phase power supply, and the output voltage can be adjusted by adjusting the voltage regulator 3, and the other end of the voltage regulator 3 is connected to a phase-shifting transformer 4, and the phase-shifting transformer 4 includes a primary winding 41, a first secondary winding 42 and a second secondary winding 43, and the voltage regulator 3 is connected to the The primary winding 41 of the phase-shifting transformer 4 is connected, the primary winding 41 adopts a star connection, the first secondary winding 42 adopts a star connection, and the second secondary winding 43 adopts a delta connection; the other end of the phase-shifting transformer 4 is connected with a rectifier circuit, the rectifier circuit is arranged inside the rectifier cabinet 5, and the rectifier circuit includes a first rectifier circuit 51 and a second rectifier circuit 52, the three terminals of the first secondary winding are respectively connected between two rectifier diodes in the three rectifier diode groups of the first rectifier circuit 51; the three terminals of the second secondary winding 43 are respectively connected between two rectifier diodes in the three rectifier diode groups of the second rectifier circuit 52, the first rectifier circuit 51 and the second rectifier circuit 52 are connected in series or in parallel, and finally an adjustable medium voltage 12-pulse DC output is formed at the X1 and X2 terminals.

[0027] In practical applications, in order to ensure safety, a connection terminal of a second grounding circuit 53 is connected between the first rectifier circuit 51 and the second rectifier circuit 52. The second grounding circuit 53 includes a grounding switch S1. One end of the grounding switch S1 is connected to the first rectifier circuit 51 and the second rectifier circuit 52. The other end of the grounding switch S1 is connected to a grounding resistor. The grounding resistor includes a resistor R1, a resistor R2, and a resistor R3 connected in series in sequence. The other end of the grounding resistor is grounded, that is, the other end of the resistor R3 is grounded. In practical applications, the grounding circuit is set in the rectifier cabinet 5, and the resistor R3 is connected to the housing of the rectifier cabinet 5 and grounded.

[0028] In practical applications, a power-on control switch 2 is provided between the three-phase power supply and the voltage regulator 3 to control the on and off of the three-phase power supply.

[0029] In practical applications, the DC source further includes a plurality of grounding resistors to be measured, and the grounding resistors to be measured are arranged between the grounding resistor and the output end of the first rectifier circuit 51 or the output end of the second rectifier circuit 52. Figure 2 As shown, the grounding resistor to be measured includes a grounding resistor to be measured RX1 and a grounding resistor to be measured RX2, wherein the grounding resistor to be measured RX1 is arranged between the output end of the first rectifier circuit 51 and the grounding resistor R3, and the grounding resistor to be measured RX2 is arranged between the output end of the second rectifier circuit 52 and the grounding resistor R3, and the other end of the grounding resistor to be measured is grounded.

[0030] In practical applications, the DC source further includes a plurality of voltmeters, the two ends of the grounding resistance to be measured are connected to the voltmeters, and the voltmeters are configured to measure the voltage value between the positive electrode and the ground, the negative electrode and the ground, and / or the positive and negative electrodes. Figure 2 As shown, the voltmeter XMM1 is set at both ends of the grounding resistor RX1 to be tested, that is, the voltmeter is in the negative state to the ground, to detect the voltage of the grounding resistor RX1 to be tested, that is, the voltmeter XMM1 is used to measure the voltage value when it is negative to the ground; the voltmeter XMM2 is set at both ends of the grounding resistor RX2 to be tested, that is, the voltmeter is in the positive state to the ground, to detect the voltage of the grounding resistor RX2 to be tested, that is, the voltmeter XMM2 is used to measure the voltage value when it is positive to the ground; the voltmeter XMM3 is connected to the voltmeter XMM1 and the voltmeter XMM2 respectively, that is, it is set between the positive and negative poles of the power supply, to measure the voltage value between the positive and negative poles of the power supply. When the voltage regulator adjusts the output voltage, it can confirm whether the adjusted voltage meets the standard by observing the readings of each voltmeter.

[0031] After taking power from the mains, a relatively stable DC pulse power supply can be output after voltage regulation, phase shifting and rectification. The output voltage can be adjusted by the voltage regulator, and the pulse output can be increased by changing the series-parallel combination of the power supply. If the power quality requirements are higher, multiple groups of filter capacitors can be connected in parallel at the output end to form a stable output. The establishment of this test power supply can meet the test requirements of the DC system insulation monitoring device for the medium-voltage DC source with neutral point grounding.

[0032] The advantages of this embodiment are as follows: after taking power from the mains, a relatively stable DC pulse power supply can be output after voltage regulation, phase shifting and rectification, which can meet the testing requirements of the DC system insulation monitoring device for a medium-voltage DC voltage source with a neutral point grounding method.

[0033] Embodiment 2:

[0034] like Figures 1 to 3 As shown, a medium voltage DC source is mainly used to test and verify the insulation monitoring device of the medium voltage DC system. In this embodiment, the medium voltage of 4000V is taken as an example, but in other embodiments, it can be other values. It includes a three-phase power supply, and the three-phase power supply is provided with a distribution cabinet 1. The distribution cabinet 1 is a mains power distribution cabinet. The distribution cabinet 1 is connected to an AC380V three-phase power supply. A first grounding circuit 11 is provided in the distribution cabinet 1. The first grounding circuit 11 includes a resistor R0. One end of the resistor R0 is connected to one end of the three-phase power supply, and the other end of the resistor R0 is grounded; the other end of the three-phase power supply is connected to a voltage regulator 3, and the voltage regulator 3 is configured to boost the three-phase power supply, and the output voltage can be adjusted by adjusting the voltage regulator 3. The other end of the voltage regulator 3 is connected to a phase-shifting transformer 4, and the phase-shifting transformer 4 includes a primary winding 41, a first secondary winding 42 and a second secondary winding 43. The voltage regulator 3 and the primary winding 41 of the phase-shifting transformer 4 are connected. The first secondary winding 42 is connected in star connection, and the second secondary winding 43 is connected in delta connection; the other end of the phase-shifting transformer 4 is connected with a rectifier circuit, and the rectifier circuit is arranged inside the rectifier cabinet 5. The rectifier circuit includes a first rectifier circuit 51 and a second rectifier circuit 52. The three terminals of the first secondary winding are respectively connected between two rectifier diodes in the three rectifier diode groups of the first rectifier circuit 51; the three terminals of the second secondary winding 43 are respectively connected between two rectifier diodes in the three rectifier diode groups of the second rectifier circuit 52. The first rectifier circuit 51 and the second rectifier circuit 52 are connected in series, and finally an adjustable DC4000V 12-pulse DC output is formed at the X1 and X2 terminals.

[0035] In practical applications, in order to ensure safety, a connection terminal of a second grounding circuit 53 is connected between the first rectifier circuit 51 and the second rectifier circuit 52. The second grounding circuit 53 includes a grounding switch S1. One end of the grounding switch S1 is connected to the first rectifier circuit 51 and the second rectifier circuit 52. The other end of the grounding switch S1 is connected to a grounding resistor. The grounding resistor includes a resistor R1, a resistor R2, and a resistor R3 connected in series in sequence. The other end of the grounding resistor is grounded, that is, the other end of the resistor R3 is grounded. In practical applications, the grounding circuit is set in the rectifier cabinet 5, and the resistor R3 is connected to the housing of the rectifier cabinet 5 and grounded.

[0036] In practical applications, a power-on control switch 2 is provided between the three-phase power supply and the voltage regulator 3 to control the on and off of the three-phase power supply.

[0037] In practical applications, the DC source further includes a plurality of grounding resistors to be measured, and the grounding resistors to be measured are arranged between the grounding resistor and the output end of the first rectifier circuit 51 or the output end of the second rectifier circuit 52. Figure 2 As shown, the grounding resistor to be measured includes a grounding resistor to be measured RX1 and a grounding resistor to be measured RX2, wherein the grounding resistor to be measured RX1 is arranged between the output end of the first rectifier circuit 51 and the grounding resistor R3, and the grounding resistor to be measured RX2 is arranged between the output end of the second rectifier circuit 52 and the grounding resistor R3, and the other end of the grounding resistor to be measured is grounded.

[0038] In practical applications, the DC source further includes a plurality of voltmeters, the two ends of the grounding resistance to be measured are connected to the voltmeters, and the voltmeters are configured to measure the voltage value between the positive electrode and the ground, the negative electrode and the ground, and / or the positive and negative electrodes. Figure 2 As shown, the voltmeter XMM1 is set at both ends of the grounding resistor RX1 to be tested, that is, the voltmeter is in the negative state to the ground, to detect the voltage of the grounding resistor RX1 to be tested, that is, the voltmeter XMM1 is used to measure the voltage value when it is negative to the ground; the voltmeter XMM2 is set at both ends of the grounding resistor RX2 to be tested, that is, the voltmeter is in the positive state to the ground, to detect the voltage of the grounding resistor RX2 to be tested, that is, the voltmeter XMM2 is used to measure the voltage value when it is positive to the ground; the voltmeter XMM3 is connected to the voltmeter XMM1 and the voltmeter XMM2 respectively, that is, it is set between the positive and negative poles of the power supply, to measure the voltage value between the positive and negative poles of the power supply. When the voltage regulator adjusts the output voltage, it can confirm whether the adjusted voltage meets the standard by observing the readings of each voltmeter.

[0039] In practical applications, according to the demand for power quality, multiple groups of filter capacitors can be connected in parallel at the output end of the rectifier cabinet to form a stable output.

[0040] In practical applications, the DC source is configured as multiple, the first rectifier circuit and the second rectifier circuit in the same DC source are connected in series, and the rectifier circuits between the multiple DC sources are connected in series and / or in parallel to form a DC4000V12 pulse rectifier DC source. Figure 3 As shown, two rectifier cabinets are used to form a DC4000V 12-pulse rectifier circuit, the first rectifier circuit and the second rectifier circuit in the first DC source 101 and the second DC source 102 are connected in series, and the first rectifier cabinet 101 and the second rectifier cabinet 102 are connected in parallel.

[0041] After taking power from the mains, it can output a relatively stable DC pulse power supply after voltage regulation, phase shifting and rectification. It can also increase the pulse output by changing the series-parallel combination of the power supply. If the power quality requirements are higher, multiple groups of filter capacitors can be connected in parallel at the output end to form a stable output. The establishment of this test power supply can meet the test requirements of the DC system insulation monitoring device for the medium-voltage DC 4000V voltage source with neutral point grounding.

[0042] The advantages of this example are: after taking power from the mains, a relatively stable DC pulse power supply can be output after voltage regulation, phase shifting and rectification, which can meet the test requirements of the DC system insulation monitoring device for a medium voltage DC 4000V voltage source with a neutral point grounding method. By connecting the first rectifier circuit and the second rectifier circuit in series and setting a plurality of DC sources, the rectifier circuits between the DC sources are connected in parallel, which increases the output of pulses and improves the quality requirements of the power supply.

[0043] Embodiment 3:

[0044] like Figures 1 to 4As shown, a medium voltage DC source is mainly used to test and verify the insulation monitoring device of the medium voltage DC system. In this embodiment, a medium voltage 4000V DC source is taken as an example, but in other embodiments, it can be other values. It includes a three-phase power supply, and the three-phase power supply is provided with a distribution cabinet 1. The distribution cabinet 1 is a mains power distribution cabinet. The distribution cabinet 1 is connected to an AC380V three-phase power supply. A first grounding circuit 11 is provided in the distribution cabinet 1. The first grounding circuit 11 includes a resistor R0. One end of the resistor R0 is connected to one end of the three-phase power supply, and the other end of the resistor R0 is grounded; the other end of the three-phase power supply is connected to a voltage regulator 3, and the voltage regulator 3 is configured to boost the three-phase power supply, and the output voltage can be adjusted by adjusting the voltage regulator 3. The other end of the voltage regulator 3 is connected to a phase-shifting transformer 4, and the phase-shifting transformer 4 includes a primary winding 41, a first secondary winding 42 and a second secondary winding 43. The voltage regulator 3 is connected to the primary winding 41 of the phase-shifting transformer 4. The primary winding 41 is connected in star, the first secondary winding 42 is connected in star, and the second secondary winding 43 is connected in delta. The other end of the phase-shifting transformer 4 is connected with a rectifier circuit, which is arranged inside the rectifier cabinet 5. The rectifier circuit includes a first rectifier circuit 51 and a second rectifier circuit 52. The three terminals of the first secondary winding are respectively connected between two rectifier diodes in the three rectifier diode groups of the first rectifier circuit 51; the three terminals of the second secondary winding 43 are respectively connected between two rectifier diodes in the three rectifier diode groups of the second rectifier circuit 52. The first rectifier circuit 51 and the second rectifier circuit 52 are connected in series or in parallel, and finally an adjustable medium voltage DC4000V 12-pulse DC output is formed at the X1 and X2 terminals.

[0045] In practical applications, in order to ensure safety, a connection terminal of a second grounding circuit 53 is connected between the first rectifier circuit 51 and the second rectifier circuit 52. The second grounding circuit 53 includes a grounding switch S1. One end of the grounding switch S1 is connected to the first rectifier circuit 51 and the second rectifier circuit 52. The other end of the grounding switch S1 is connected to a grounding resistor. The grounding resistor includes a resistor R1, a resistor R2, and a resistor R3 connected in series in sequence. The other end of the grounding resistor is grounded, that is, the other end of the resistor R3 is grounded. In practical applications, the grounding circuit is set in the rectifier cabinet 5, and the resistor R3 is connected to the housing of the rectifier cabinet 5 and grounded.

[0046] In practical applications, a power-on control switch 2 is provided between the three-phase power supply and the voltage regulator 3 to control the on and off of the three-phase power supply.

[0047] In practical applications, the DC source further includes a plurality of grounding resistors to be measured, and the grounding resistors to be measured are arranged between the grounding resistor and the output end of the first rectifier circuit 51 or the output end of the second rectifier circuit 52. Figure 2 As shown, the grounding resistor to be measured includes a grounding resistor to be measured RX1 and a grounding resistor to be measured RX2, wherein the grounding resistor to be measured RX1 is arranged between the output end of the first rectifier circuit 51 and the grounding resistor R3, and the grounding resistor to be measured RX2 is arranged between the output end of the second rectifier circuit 52 and the grounding resistor R3, and the other end of the grounding resistor to be measured is grounded.

[0048] In practical applications, the DC source further includes a plurality of voltmeters, the two ends of the grounding resistance to be measured are connected to the voltmeters, and the voltmeters are configured to measure the voltage value between the positive electrode and the ground, the negative electrode and the ground, and / or the positive and negative electrodes. Figure 2 As shown, the voltmeter XMM1 is set at both ends of the grounding resistor RX1 to be tested, that is, the voltmeter is in the negative state to the ground, to detect the voltage of the grounding resistor RX1 to be tested, that is, the voltmeter XMM1 is used to measure the voltage value when it is negative to the ground; the voltmeter XMM2 is set at both ends of the grounding resistor RX2 to be tested, that is, the voltmeter is in the positive state to the ground, to detect the voltage of the grounding resistor RX2 to be tested, that is, the voltmeter XMM2 is used to measure the voltage value when it is positive to the ground; the voltmeter XMM3 is connected to the voltmeter XMM1 and the voltmeter XMM2 respectively, that is, it is set between the positive and negative poles of the power supply, to measure the voltage value between the positive and negative poles of the power supply. When the voltage regulator adjusts the output voltage, it can confirm whether the adjusted voltage meets the standard by observing the readings of each voltmeter.

[0049] In practical applications, according to the demand for power quality, multiple groups of filter capacitors can be connected in parallel at the output end of the rectifier cabinet to form a stable output.

[0050] In practical applications, the DC source is configured as multiple, the first rectifier circuit and the second rectifier circuit in the same DC source are connected in parallel, and the rectifier circuits between the multiple DC sources are connected in series and / or in parallel to form a DC4000V 24-pulse rectifier DC source. Figure 4 As shown, four rectifier cabinets are used to form a DC4000V 24-pulse rectifier circuit, the first rectifier circuit and the second rectifier circuit in the third DC source 103, the fourth DC source 104, the fifth DC source 105 and the sixth DC source 106 are all connected in parallel, the rectifier circuits of the third DC source 103 and the fourth DC source 104 are connected in series, and the rectifier circuits of the fifth DC source 105 and the sixth DC source 106 are connected in series, and then the third DC source 103 and the fourth DC source 104 connected in series are connected in parallel with the fifth DC source 105 and the sixth DC source 106 connected in series, that is, the two groups of rectifier cabinets connected in series are connected in parallel.

[0051] After taking power from the mains, it can output a relatively stable DC pulse power supply after voltage regulation, phase shifting and rectification. It can also increase the pulse output by changing the series-parallel combination of the power supply. If the power quality requirements are higher, multiple groups of filter capacitors can be connected in parallel at the output end to form a stable output. The establishment of this test power supply can meet the test requirements of the DC system insulation monitoring device for the medium-voltage DC 4000V voltage source with neutral point grounding.

[0052] Advantages of this embodiment: After taking power from the mains, a relatively stable DC pulse power supply can be output after voltage regulation, phase shifting and rectification, which can meet the test requirements of the DC system insulation monitoring device for the medium voltage DC 4000V voltage source using the neutral point grounding method. The output of the pulse can be changed by changing the series-parallel connection mode of the first rectifier circuit and the second rectifier circuit. By setting multiple DC sources and changing the series-parallel connection mode of the rectifier circuits between the DC sources, the output of the pulse can be increased and the quality requirements of the power supply can be improved.

[0053] Advantages of the present invention:

[0054] After being powered by the mains, a relatively stable DC pulse power supply can be output after voltage regulation, phase shifting and rectification, which can meet the test requirements of the DC system insulation monitoring device for the medium-voltage DC source with neutral point grounding. The output of the pulse is changed by changing the series-parallel connection mode of the first rectifier circuit and the second rectifier circuit. By setting up multiple DC sources and changing the series-parallel connection mode of the rectifier circuits between the DC sources, the output of the pulse is increased, a stable power supply output is formed, and the quality requirements of the power supply are improved. A medium-voltage DC source provided by the present invention can output a relatively stable DC pulse power supply after voltage regulation, phase shifting and rectification after being powered by the mains. The output voltage can be adjusted by a voltage regulator, and the pulse output can be increased by changing the series-parallel combination connection method of the power supply.

[0055] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A medium voltage DC source, comprising a three-phase power supply, a voltage regulator connected to the three-phase power supply, and a phase shifting transformer connected to the voltage regulator, characterized in that: It also includes a rectifier circuit, which is connected to the phase-shifting transformer. The rectifier circuit includes a first rectifier circuit and a second rectifier circuit. The phase-shifting transformer includes a primary winding, a first secondary winding and a second secondary winding. The voltage regulator is connected to the primary winding of the phase-shifting transformer. The primary winding adopts a star connection, the first secondary winding adopts a star connection, and the second secondary winding adopts a triangle connection; the three terminals of the first secondary winding are respectively connected between two rectifier diodes in the three groups of rectifier diodes in the first rectifier circuit; the three terminals of the second secondary winding are respectively connected between two rectifier diodes in the three groups of rectifier diodes in the second rectifier circuit, and the first rectifier circuit and the second rectifier circuit are connected in series or in parallel.

2. The medium voltage DC source according to claim 1, characterized in that: The DC source is configured as a plurality of DC sources, the first rectifier circuit and the second rectifier circuit in the same DC source are connected in parallel, and the rectifier circuits between the plurality of DC sources are connected in series and / or in parallel to form a 24-pulse rectifier DC source.

3. The medium voltage DC source according to claim 1, characterized in that: The DC source is configured as a plurality of DC sources, wherein the first rectifier circuit and the second rectifier circuit in the same DC source are connected in series, and the rectifier circuits between the plurality of DC sources are connected in series and / or in parallel to form a 12-pulse rectifier DC source.

4. The medium voltage DC source according to claim 1, characterized in that: It also includes a second grounding circuit, the connection terminal of the second grounding circuit is arranged between the first rectifier circuit and the second rectifier circuit, the second grounding circuit includes a grounding switch S1, one end of the grounding switch S1 is connected to the first rectifier circuit and the second rectifier circuit, the other end of the grounding switch S1 is connected to a grounding resistor, and the other end of the grounding resistor is grounded.

5. The medium voltage DC source according to claim 4, characterized in that: The grounding resistor includes a resistor R1, a resistor R2 and a resistor R3 which are sequentially connected in series.

6. The medium voltage DC source according to claim 5, characterized in that: The rectifier circuit is installed in a rectifier cabinet, and the resistor R3 is connected to the rectifier cabinet housing and grounded.

7. The medium voltage DC source according to claim 4, characterized in that: It also includes a plurality of grounding resistors to be measured, wherein the grounding resistors to be measured are arranged between the grounding resistor and the output end of the first rectifier circuit or the output end of the second rectifier circuit, and the other end of the grounding resistor to be measured is grounded.

8. The medium voltage DC source according to claim 1, characterized in that: It also includes multiple voltmeters, both ends of the grounding resistor to be measured are connected to the voltmeters, the voltmeters are used to detect the voltage value of the resistor to be measured, and the voltmeters are configured to measure the voltage value between the positive and ground, the negative and ground, and / or between the positive and negative poles.

9. The medium voltage DC source according to claim 1, characterized in that: It also includes a power-on control switch, which is arranged between the three-phase power supply and the voltage regulator and is used to control the on and off of the three-phase power supply.

10. The medium voltage DC source according to claim 1, characterized in that: The three-phase power supply is provided with a distribution cabinet, and a first grounding circuit is provided in the distribution cabinet. The first grounding circuit is connected to the three-phase power supply. The first grounding circuit includes a resistor R0, one end of the resistor R0 is connected to the three-phase power supply, and the other end of the resistor R0 is grounded.

Images