Harmonic power consumption compensation method of direct current arrester and direct current arrester

Abstract

This invention provides a harmonic power consumption compensation method and a DC surge arrester to solve the technical problem that existing DC surge arresters suffer from aging, shortened service life, and reduced reliability due to the presence of a large number of harmonics. The harmonic power consumption compensation method for a DC surge arrester provided by this invention is as follows: A compensation voltage limiting element MOV2 is connected in series at the output or input terminal of the original voltage limiting element MOV1 of the DC surge arrester to increase the overall reference voltage Uref of the arrester; a gap GAP is connected in parallel across the compensation voltage limiting element MOV2. When the DC surge arrester absorbs an overvoltage, the gap GAP discharges, the compensation voltage limiting element MOV2 is bypassed, and the residual voltage of the DC surge arrester is equal to the residual voltage of the original voltage limiting element MOV1; under normal operating voltage, the gap GAP does not discharge, and the voltage borne by the DC surge arrester is shared by the original voltage limiting element MOV1 and the compensation voltage limiting element MOV2, and the overall reference voltage Uref of the DC surge arrester is equal to the reference voltage U of the original voltage limiting element MOV1. mov1ref and the reference voltage U of the compensation and voltage limiting element MOV2 mov2ref sum.

Description

Technical Field

[0001] This invention relates to DC pole line arresters, and more particularly to a method for harmonic power consumption compensation of DC arresters and a DC arrester. Background Technology

[0002] DC pole-line surge arresters are widely used in power systems such as urban rail transit, photovoltaic power generation, and DC distribution networks, and are important protection devices for DC bus equipment. For example... Figure 1 As shown, the original voltage-limiting element MOV1 of a DC pole arrester is typically connected between the DC pole and ground. DC systems, due to the extensive use of power electronic equipment, contain numerous harmonics. For example, urban rail transit systems contain a large number of harmonics in their DC traction systems, increasing the power consumption of the DC arrester and effectively raising its operating voltage. For DC arresters, the equivalent operating voltage and charge rate including harmonic power consumption are greater than those without harmonics. Therefore, harmonics in the DC system accelerate the aging of the DC arrester, shorten its service life, and reduce its operational reliability. How to compensate for harmonic power consumption is a crucial issue that needs to be considered in the design and manufacturing of DC arresters. Summary of the Invention

[0003] The purpose of this invention is to solve the technical problem that existing DC surge arresters are prone to aging, have shortened service life, and reduced reliability due to the presence of a large number of harmonics, and to provide a harmonic power consumption compensation method for DC surge arresters and a DC surge arrester.

[0004] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0005] A method for harmonic power consumption compensation of a DC surge arrester, characterized by the following steps:

[0006] Step 1: Connect a compensation voltage limiting element MOV2 in series at the output or input terminal of the original voltage limiting element MOV1 of the DC surge arrester to increase the overall reference voltage Uref of the surge arrester;

[0007] The compensation and voltage limiting element MOV2 has a gap GAP connected in parallel at both ends;

[0008] The current-carrying capacity of the gap GAP is greater than or equal to the current-carrying capacity of the original pressure-limiting element MOV1;

[0009] Step 2: When the DC surge arrester absorbs overvoltage, the gap GAP breaks down and discharges, causing the compensation voltage limiting element MOV2 to be bypassed. The voltage that the DC surge arrester bears is borne by the original voltage limiting element MOV1, and the residual voltage of the DC surge arrester is equal to the residual voltage of the original voltage limiting element MOV1.

[0010] When the DC surge arrester operates at normal voltage, the gap GAP does not discharge. The voltage across the DC surge arrester is shared by the original voltage limiting element MOV1 and the compensating voltage limiting element MOV2. The overall reference voltage Uref of the DC surge arrester is equal to the reference voltage U of the original voltage limiting element MOV1. mov1ref and the reference voltage U of the compensation and voltage limiting element MOV2 mov2ref The sum of U mov2ref The equivalent voltage U used to compensate for the increase in harmonic power consumption h .

[0011] Further, in step 2, the reference voltage U of the compensation voltage limiting element MOV2 mov2ref The following formula should be satisfied:

[0012]

[0013] Where η is the charge rate of the DC surge arrester, and the value of η is 80% to 85%; U d U is the DC component of the DC pole voltage; h This is the equivalent harmonic voltage.

[0014] Further, in step 1, the discharge voltage of the gap GAP is set to the reference voltage U of the compensation voltage limiting element MOV2. mov2ref It is 1.1-1.2 times that of the gap to ensure that the gap operates only under impulse voltage and impulse current.

[0015] The present invention also provides a DC surge arrester, which is characterized in that it includes a primary voltage limiting element MOV1, a compensating voltage limiting element MOV2, and a gap GAP.

[0016] One end of the original voltage limiting element MOV1 is connected to one end of the compensation voltage limiting element MOV2;

[0017] The other end of the original voltage limiting element MOV1 is used to connect to the DC pole line, and the other end of the compensation voltage limiting element MOV2 is used to ground; or the other end of the original voltage limiting element MOV1 is used to ground, and the other end of the compensation voltage limiting element MOV2 is used to connect to the DC pole line.

[0018] The compensation voltage limiting element MOV2 is used to increase the overall reference voltage Uref of the DC surge arrester to compensate for harmonic power consumption and reduce the charge rate η of the DC surge arrester.

[0019] The gap GAP is connected in parallel with the compensation voltage limiting element MOV2, and the current carrying capacity of the gap GAP is greater than or equal to the current carrying capacity of the original voltage limiting element MOV1.

[0020] The gap GAP is used for breakdown discharge during overvoltage, bypassing the compensation voltage limiting element MOV2, and the residual voltage of the DC surge arrester is equal to the residual voltage of the original voltage limiting element MOV1. When the DC surge arrester operates at normal voltage, the voltage borne by the DC surge arrester is shared by the original voltage limiting element MOV1 and the compensation voltage limiting element MOV2, and the overall reference voltage Uref of the DC surge arrester is equal to the reference voltage U of the original voltage limiting element MOV1. mov1ref and the reference voltage U of the compensation and voltage limiting element MOV2 mov2ref The sum of U mov2ref The equivalent voltage U used to compensate for the increase in harmonic power consumption h .

[0021] Furthermore, the compensation voltage limiting element MOV reference voltage U mov2ref The following formula should be satisfied:

[0022]

[0023] Where η is the charge rate of the DC surge arrester, and the value of η is 80% to 85%; U d U is the DC component of the DC pole voltage; h This is the equivalent harmonic voltage.

[0024] Furthermore, the discharge voltage of the gap GAP is set to the reference voltage U of the compensation voltage limiting element MOV2. mov2ref It is 1.1-1.2 times that of the gap to ensure that the gap operates only under impulse voltage and impulse current.

[0025] Furthermore, the original pressure limiting element MOV1 includes a first valve plate and a second valve plate;

[0026] The compensation and pressure limiting element MOV2 includes a third valve plate;

[0027] The second valve plate, the first valve plate, the third valve plate, and the gap GAP are stacked sequentially from bottom to top, and an insulating gasket is provided between the first valve plate and the third valve plate.

[0028] The upper end of the gap GAP is connected to the lower end of the third valve plate through the first parallel conductor C1; the lower end of the gap GAP is connected to the upper end of the first valve plate through the second parallel conductor C2.

[0029] Alternatively, the first valve plate is connected to the upper end of the second valve plate; the gap GAP and the third valve plate are connected side by side to the upper end of the first valve plate, and the upper end of the gap GAP is connected to the upper end of the third valve plate.

[0030] Furthermore, the gap GAP is a gas discharge tube, a plate gap, or a ceramic ring gap.

[0031] Furthermore, both the first parallel conductor C1 and the second parallel conductor C2 are copper connecting strips.

[0032] The beneficial effects of this invention are:

[0033] 1. The present invention provides a method for harmonic power consumption compensation of a DC surge arrester. By connecting a compensation voltage limiting element MOV2 in series at one end of the original voltage limiting element MOV1, the overall reference voltage Uref of the surge arrester is increased, thus compensating for the equivalent voltage increase caused by harmonic power consumption. At the same time, a gap GAP is connected in parallel across the compensation voltage limiting element MOV2. When the surge arrester absorbs overvoltage, the gap GAP discharges, bypassing the compensation voltage limiting element MOV2, so that the residual voltage of the DC surge arrester is equal to the residual voltage of the original voltage limiting element MOV1, thereby improving the overvoltage protection capability of the DC surge arrester. This method is simple, efficient, and easy to operate.

[0034] 2. The DC surge arrester provided by this invention compensates for harmonic power consumption by connecting a compensating voltage limiting element MOV2 in series at one end of the original voltage limiting element MOV1, thereby increasing the overall reference voltage Uref of the surge arrester and reducing the charge rate η of the surge arrester. At the same time, a gap GAP is set in parallel on the compensating voltage limiting element MOV2, which reduces the charge rate η and power consumption of the surge arrester without increasing the residual voltage, thereby improving the overvoltage protection capability of the DC surge arrester. It has great application prospects in power systems such as urban rail transit, photovoltaic power generation, and DC distribution networks.

[0035] 3. The DC surge arrester provided by the present invention has a gap GAP and a compensation voltage limiting element MOV2 stacked together, which saves the overall space of the DC surge arrester. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the circuit connection of an existing DC surge arrester;

[0037] Figure 2 This is a schematic diagram showing the relationship between the equivalent DC voltage Ue, the DC component of the DC pole voltage Ud, and the equivalent harmonic voltage Uh.

[0038] Figure 3 This is a circuit connection diagram of a DC surge arrester according to the present invention;

[0039] Figure 4 This is a schematic diagram of the structure of an embodiment of a DC surge arrester according to the present invention;

[0040] Figure 5 This is a schematic diagram of another embodiment of a DC surge arrester according to the present invention;

[0041] Figure 6 This is a comparison of the volt-ampere characteristic curves of the DC surge arrester with gap GAP of the present invention and the conventional DC surge arrester with only the original voltage limiting element MOV1.

[0042] Figure 7 This is a residual voltage waveform diagram of an embodiment of a DC surge arrester according to the present invention.

[0043] The specific reference numerals in the attached figures are as follows:

[0044] 11-First valve plate; 12-Second valve plate; 21-Third valve plate; 4-Insulating gasket. Detailed Implementation

[0045] To make the advantages and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] This invention provides a method for harmonic power consumption compensation of a DC surge arrester, specifically including the following steps:

[0047] Step 1: Connect a compensation voltage limiting element MOV2 in series at the output or input terminal of the original voltage limiting element MOV1 of the DC surge arrester to increase the overall reference voltage Uref of the DC surge arrester and compensate for the increased equivalent voltage due to harmonic power consumption. However, since the volt-ampere characteristic of the DC surge arrester is fixed, increasing the overall reference voltage Uref will also increase its residual voltage. Therefore, this invention sets a gap GAP in parallel across the series compensation voltage limiting element MOV2. The current carrying capacity of the gap GAP is greater than or equal to the current carrying capacity of the original voltage limiting element MOV1. In this embodiment, the 2ms square wave impulse current should be no less than 1200A / 20 times, the 4 / 10us large impulse current should be no less than 100kA / 2 times, and the 8 / 20us lightning impulse current should be no less than 20kA / 20 times.

[0048] Step 2: When the DC surge arrester absorbs overvoltage, the gap GAP breaks down and discharges, causing the compensation voltage limiting element MOV2 to be bypassed. The voltage that the DC surge arrester bears is borne by the original voltage limiting element MOV1. The residual voltage of the DC surge arrester is equal to the residual voltage of the original voltage limiting element MOV1, thus ultimately achieving harmonic power consumption compensation of the DC surge arrester.

[0049] When the DC surge arrester operates at normal voltage, the gap GAP does not discharge. The voltage across the DC surge arrester is shared by the original voltage limiting element MOV1 and the compensating voltage limiting element MOV2. The overall reference voltage Uref of the DC surge arrester is equal to the reference voltage U of the original voltage limiting element MOV1. mov1ref and the reference voltage U of the compensation and voltage limiting element MOV2 mov2ref The sum of U mov2ref The equivalent voltage U used to compensate for the increase in harmonic power consumption h .

[0050] The reference voltage U of the compensation voltage limiting element MOV2 mov2ref The following formula should be satisfied:

[0051]

[0052] In formula (1), η is the charge rate of the DC surge arrester, and the value of η is 80% to 85%; U d U is the DC component of the DC pole voltage; h This is the equivalent harmonic voltage.

[0053] Among them, the original voltage limiting element MOV1 reference voltage U mov1ref The charge rate η should be 80%–85% under conditions free from harmonic effects, and the residual voltage of the original voltage limiting element MOV1 should meet the insulation coordination requirements of the DC system. Simultaneously, the discharge voltage of the gap GAP should be set to the reference voltage U of the compensation voltage limiting element MOV2. mov2ref It is 1.1-1.2 times that of the gap to ensure that the gap operates only under impulse voltage and impulse current.

[0054] Specifically, during operation, the DC pole voltage It is the vector sum of DC voltage and harmonic voltage, i.e.

[0055]

[0056] In formula (2), U d The DC component represents the DC pole voltage; n represents the harmonic order. Represents the nth harmonic component of the DC pole line voltage; This represents the equivalent harmonic voltage.

[0057] The power consumption P of the DC pole arrester is the DC power consumption P of the arrester. d With the nth harmonic power consumption P of the surge arrester n The sum of

[0058]

[0059] The mechanism of harmonic power consumption is the conductivity and polarization of metal oxides, which can be expressed by the following formula:

[0060]

[0061] In formula (4), Un represents the nth harmonic voltage; G represents the harmonic conductance of the metal oxide resistor; f represents the fundamental frequency; C represents the equivalent capacitance of the metal oxide nonlinear resistor; and tanδ represents the loss factor of the metal oxide nonlinear resistor.

[0062] Typically, the nth harmonic voltage Un lies in the linear region of the nonlinear resistive voltage-current characteristic of metal oxides, and its conduction loss is not sensitive to the harmonic order n. However, the harmonic order n is proportional to its dielectric polarization loss; therefore, higher harmonics will generate significant power consumption. Since the conduction current is only in the microampere range, the harmonic conduction loss can be ignored. Therefore, harmonic losses are mainly polarization losses, and can be considered as the losses under the following equivalent harmonic voltage:

[0063]

[0064] In formula (5), U e (n) represents the equivalent voltage of the nth harmonic.

[0065] The effective value of the inter-terminal operating voltage of the surge arrester reflects the influence of harmonic power dissipation and can be called the equivalent DC voltage Ue. The relationship between the equivalent DC voltage Ue, the DC component of the DC pole voltage Ud, and the equivalent harmonic voltage Uh is as follows: Figure 2 As shown. Due to the orthogonality of trigonometric functions, the equivalent DC voltage Ue should satisfy the following equation:

[0066]

[0067] As can be seen from formula (6), when the DC system contains a large number of harmonics, these harmonics increase the power consumption of the DC surge arrester, and the effective value of the equivalent DC voltage Ue, that is, the operating voltage between the terminals of the DC surge arrester, increases accordingly.

[0068] Existing DC surge arresters are connected between the DC pole and ground. To obtain good voltage limiting characteristics, the reference voltage of the original voltage limiting element is usually designed to be about 1.25 times the maximum system voltage, that is, the charge rate η of the DC surge arrester is about 80% to 85%, to avoid excessively high charge rates that accelerate the aging of the DC surge arrester. The charge rate η of the DC surge arrester is related to the equivalent DC voltage U of the DC surge arrester. e The relationship between the surge arrester's overall reference voltage Uref and the surge arrester can be expressed by the following formula:

[0069]

[0070] Substituting formula (6) into formula (7), we get the following formula:

[0071]

[0072] It can be seen from formula (8) that the equivalent DC voltage U of the DC surge arrester eIn cases of increased voltage, increasing the overall reference voltage Uref of the DC surge arrester can keep the arrester's charge rate η constant. Therefore, this invention connects a compensating voltage limiting element MOV2 in series at the output or input of the original voltage limiting element MOV1 to increase the overall reference voltage Uref of the DC surge arrester, compensating for the increased equivalent voltage due to harmonic power consumption. Simultaneously, to avoid increasing the residual voltage along with the reference voltage, a gap GAP is connected in parallel across the compensating voltage limiting element MOV2, ensuring that the residual voltage of the DC surge arrester is equal to the residual voltage of the original voltage limiting element MOV1, ultimately achieving harmonic power consumption compensation for the DC surge arrester.

[0073] Since the overall reference voltage Uref of the DC surge arrester is the reference voltage U of the original voltage limiting element MOV1, mov1ref and the reference voltage U of the compensation voltage limiting element MOV2 mov2ref The sum, according to formula (8), is the reference voltage U of the compensation voltage limiting element MOV2. mov2ref The following formula must be satisfied:

[0074]

[0075] This invention also provides a DC surge arrester capable of compensating for harmonic power consumption. The harmonic power consumption compensation method described above is used for harmonic power consumption compensation, specifically as follows: Figure 3 As shown, the DC surge arrester provided in this embodiment is applied to 1500V rail transit. It includes a primary voltage limiting element MOV1, a compensating voltage limiting element MOV2, and a gap GAP. One end of the primary voltage limiting element MOV1 is connected to one end of the compensating voltage limiting element MOV2. The other end of the primary voltage limiting element MOV1 is used to connect to the DC pole line, and the other end of the compensating voltage limiting element MOV2 is grounded. This increases the overall reference voltage Uref of the DC surge arrester by connecting the compensating voltage limiting element MOV2 in series, thereby compensating for harmonic power consumption and reducing the overall charge rate. In other embodiments of the present invention, the other end of the primary voltage limiting element MOV1 can also be grounded, and the other end of the compensating voltage limiting element MOV2 can be connected to the DC pole line. The gap GAP is connected in parallel with the compensating voltage limiting element MOV2, and the current carrying capacity of the gap GAP is greater than or equal to the current carrying capacity of the primary voltage limiting element MOV1. When the DC surge arrester absorbs an overvoltage, the gap GAP breaks down and discharges, the compensating voltage limiting element MOV2 is bypassed, and the residual voltage of the DC surge arrester is equal to the residual voltage of the original voltage limiting element MOV1, thus preventing the residual voltage of the DC surge arrester from rising. Under normal operating voltage, the parallel gap GAP does not discharge, and the system voltage is shared by the original voltage limiting element MOV1 and the compensating voltage limiting element MOV2. The reference voltage Uref of the DC surge arrester is equal to the reference voltage U of the original voltage limiting element MOV1. mov1ref and the reference voltage U of the compensation and voltage limiting element MOV2 mov2ref sum.

[0076] The gap GAP of this invention can be selected from gas discharge tubes, flat plate gaps, or ceramic ring gaps. In this embodiment, the gap GAP uses a gas discharge tube, which can ensure very stable discharge characteristics when applied to 1500V rail transit. Both the original voltage limiting element MOV1 and the compensating voltage limiting element MOV2 are composed of valve plates. The number of valve plates is related to the voltage level of the system, increasing as the system voltage level increases. Therefore, as... Figure 4 As shown, the original pressure limiting element MOV1 in this embodiment includes a first valve plate 11 and a second valve plate 12, while the compensation pressure limiting element MOV2 consists only of a third valve plate 21. The gap GAP and the third valve plate 21 can be connected in parallel or stacked in parallel. To save space, in this embodiment, the second valve plate 12, the first valve plate 11, the third valve plate 21, and the gap GAP are stacked sequentially from bottom to top. The upper end of the gap GAP is connected to the lower end of the third valve plate 21 through the first parallel conductor C1, and the lower end of the gap GAP is connected to the upper end of the first valve plate 11 through the second parallel conductor C2. At this time, in order to prevent the third valve plate 21 and the gap 3 from being bypassed by the first parallel conductor C1 and the second parallel conductor C2, an insulating gasket 4 is provided between the third valve plate 21 and the first valve plate 11. In this embodiment, both the first parallel conductor C1 and the second parallel conductor C2 are copper connecting strips. In other embodiments of the present invention, the gap GAP and the third valve plate 21 can also be connected by other conductors, such as copper wires, busbars, etc. It is understood that when the gap GAP and the third valve plate 21 are connected in parallel in other embodiments, their connection structure is as follows: Figure 5 As shown, there is no need to set the first parallel conductor C1 and the second parallel conductor C2, nor is there a need to set the insulating gasket 4. Usually, the busbar conductor parallel gap GAP and the third valve plate 21 are used.

[0077] Since the reference voltage Uref of the DC surge arrester is the reference voltage U of the original voltage limiting element MOV1, mov1ref and the reference voltage U of the compensation and voltage limiting element MOV2 mov2ref The sum of these values, under the condition that the surge arrester charge rate η satisfies 80% to 85%, is the reference voltage U of the compensation voltage limiting element MOV2. mov2ref It should be able to compensate for harmonic equivalent voltage, that is, compensate for the reference voltage U of the voltage limiting element MOV2. mov2ref The following formula should be satisfied:

[0078]

[0079] like Figure 6The figure shows a comparison of the volt-ampere characteristic curves of the DC surge arrester with gap (GAP) of this invention and the conventional DC surge arrester with only the original voltage limiting element MOV1. Curve oecd represents the volt-ampere characteristic curve of the conventional DC surge arrester with only the original voltage limiting element MOV1, with its reference voltage and reference current located at R2, and the 10kA residual voltage located at d. Curve oabcdeao represents the volt-ampere characteristic curve of the DC surge arrester of this invention that can compensate for harmonic power consumption. At point b (approximately 4800V), the gap discharges, and the overall voltage drops to point c. Afterward, as the current increases, the voltage changes along curve cd. When the system returns to normal, the gap (GAP) extinguishes at the system voltage, i.e., point e (approximately 1500V), and the volt-ampere characteristic curve returns to the origin along ao. The overall reference voltage Uref and reference current of the DC surge arrester with gap (GAP) of this invention are located at R1, which is greater than the voltage at R2. At a system voltage of 1500V (point e on the curve), the current of the conventional DC surge arrester with only the original voltage-limiting element MOV1 (the current corresponding to point e) is greater than the current of the DC surge arrester with gap GAP of this invention (the current corresponding to point f). Therefore, the power consumption of the former is greater than that of the latter. Figure 6 As can be seen from the current-voltage characteristic curve, the DC surge arrester with gap (GAP) of the present invention shifts upward in the low current region, i.e., when the current is less than 100mA, which reduces the current, power consumption, and charge rate in the low current region; in the impulse current region, i.e., when the current is greater than 100A, the current-voltage characteristic curve remains unchanged, so that the protection characteristics of the DC surge arrester remain unchanged and meet the requirements of insulation coordination.

[0080] To verify the performance of the DC surge arrester capable of compensating for harmonic power consumption according to the present invention, the DC surge arrester provided in this embodiment was applied to a 1500V rail transit system. The compensation voltage limiting element MOV2 reference voltage U mov2ref Set to 1.4kV, the original voltage limiting element MOV1 reference voltage U mov1ref If set to 2.8kV, then the overall reference voltage Uref of the DC surge arrester is 4.2kV, and the impulse discharge voltage of the gap GAP is 1.6kV. The residual voltage test waveform is as follows: Figure 7 As shown, after the transformation ratio conversion of the shunt and voltage divider, it can be seen that the peak value of the negative polarity lightning current (CurB) of the 8 / 20us waveform of the DC surge arrester is 10kA, and the peak value of the negative polarity residual voltage (CurA) is 4.8kV, which is the same as the residual voltage of the original voltage limiting element MOV1. This indicates that the protection characteristics of the DC surge arrester that can compensate for harmonic power consumption provided by the present invention do not increase with the increase of the reference voltage.

[0081] The DC surge arrester with harmonic power loss compensation provided by this invention can have various structures and can be applied to DC systems of different voltage levels, such as rail transit, photovoltaic power generation, and DC distribution networks. The above is only one specific embodiment of this invention. In other embodiments, as the voltage level increases, the original voltage limiting element MOV1 and the compensation voltage limiting element MOV2 will also have corresponding valve plates added to meet the performance requirements of the surge arrester.

[0082] The above description is only used to illustrate the technical solutions of the present invention, and is not intended to limit them. For those skilled in the art, modifications can be made to the specific technical solutions described in the above embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions protected by the present invention.

Claims

1. A method for harmonic power consumption compensation of a DC surge arrester, characterized in that, Includes the following steps: Step 1: Connect the compensation voltage limiting element MOV2 in series at the output or input terminal of the original voltage limiting element MOV1 of the DC surge arrester; Both the original voltage limiting element MOV1 and the compensation voltage limiting element MOV2 are composed of valve plates, and the number of valve plates is related to the voltage level of the system. The compensation and voltage limiting element MOV2 has a gap GAP connected in parallel at both ends; The current-carrying capacity of the gap GAP is greater than or equal to the current-carrying capacity of the original pressure-limiting element MOV1; Step 2: When the DC surge arrester absorbs overvoltage, the gap GAP breaks down and discharges, causing the compensation voltage limiting element MOV2 to be bypassed. The voltage that the DC surge arrester bears is borne by the original voltage limiting element MOV1, and the residual voltage of the DC surge arrester is equal to the residual voltage of the original voltage limiting element MOV1. When the DC surge arrester operates at normal voltage, the voltage it withstands is shared by the original voltage limiting element MOV1 and the compensating voltage limiting element MOV2. The overall reference voltage Uref of the DC surge arrester is the reference voltage of the original voltage limiting element MOV1. and the reference voltage of the compensation and voltage limiting element MOV2 the sum of Equivalent harmonic voltage used to compensate for increased harmonic power consumption ; The reference voltage of the compensation voltage limiting element MOV2 The following formula should be satisfied: ； in: The charge rate of the DC surge arrester. The value ranges from 80% to 85%; This represents the DC component of the DC pole line voltage. Equivalent harmonic voltage; = = U e U is the equivalent DC voltage, n is the harmonic order, and U is the harmonic voltage. n The voltage is the nth harmonic.

2. The harmonic power consumption compensation method for a DC surge arrester according to claim 1, characterized in that: In step 1, the discharge voltage of the gap GAP is set as the reference voltage of the compensation voltage limiting element MOV2. It is 1.1-1.2 times that of the gap to ensure that the gap operates only under impulse voltage and impulse current.

3. A DC surge arrester, employing the harmonic power consumption compensation method for a DC surge arrester as described in claim 1 or 2, characterized in that: This includes the original voltage limiting element MOV1, the compensation voltage limiting element MOV2, and the gap GAP; One end of the original voltage limiting element MOV1 is connected to one end of the compensation voltage limiting element MOV2; Both the original voltage limiting element MOV1 and the compensation voltage limiting element MOV2 are composed of valve plates, and the number of valve plates is related to the voltage level of the system. The other end of the original voltage limiting element MOV1 is used to connect to the DC pole line, and the other end of the compensation voltage limiting element MOV2 is used to ground; or the other end of the original voltage limiting element MOV1 is used to ground, and the other end of the compensation voltage limiting element MOV2 is used to connect to the DC pole line. The compensation voltage limiting element MOV2 is used to increase the overall reference voltage Uref of the DC surge arrester to compensate for harmonic power consumption and reduce the charge rate of the DC surge arrester. ; The gap GAP is connected in parallel with the compensation voltage limiting element MOV2, and the current carrying capacity of the gap GAP is greater than or equal to the current carrying capacity of the original voltage limiting element MOV1. The gap GAP is used for breakdown discharge during overvoltage, so that the compensation voltage limiting element MOV2 is bypassed. The reference voltage of the compensation and voltage limiting element MOV2 The following formula should be satisfied: ； in: The charge rate of the DC surge arrester. The value ranges from 80% to 85%; This represents the DC component of the DC pole line voltage. Equivalent harmonic voltage; = = U e U is the equivalent DC voltage, n is the harmonic order, and U is the harmonic voltage. n The voltage is the nth harmonic.

4. A DC surge arrester according to claim 3, characterized in that: The discharge voltage of the gap GAP is set to 1.1-1.2 times the reference voltage of the compensation voltage limiting element MOV2.

5. A DC surge arrester according to claim 3 or 4, characterized in that: The original pressure limiting element MOV1 includes a first valve plate (11) and a second valve plate (12). The compensation and pressure limiting element MOV2 includes a third valve plate (21); The second valve plate (12), the first valve plate (11), the third valve plate (21), and the gap GAP are stacked sequentially from bottom to top. An insulating gasket (4) is provided between the first valve plate (11) and the third valve plate (21). The upper end of the gap GAP is connected to the lower end of the third valve plate (21) through the first parallel conductor C1. The lower end of the gap GAP is connected to the upper end of the first valve plate (11) through the second parallel conductor C2. Alternatively, the first valve plate (11) is connected to the upper end of the second valve plate (12); the gap GAP and the third valve plate (21) are connected side by side to the upper end of the first valve plate (11), and the upper end of the gap GAP is connected to the upper end of the third valve plate (21).

6. A DC surge arrester according to claim 5, characterized in that: The gap GAP is a gas discharge tube, a plate gap, or a ceramic ring gap.

7. A DC surge arrester according to claim 6, characterized in that: Both the first parallel conductor C1 and the second parallel conductor C2 are copper connecting strips.

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