Converter valve cooling system water circuit for suppressing leakage current of equalizing electrode

Abstract

The application provides a converter valve cooling system water circuit for inhibiting leakage current of a grading electrode, comprising: an anode valve section, a cathode valve section and a cooling water pipe; the anode valve section and the cathode valve section are respectively arranged on two sides of the cooling water pipe and communicate with the cooling water pipe; the anode valve section and the cathode valve section each comprise a plurality of parallel aluminum radiators; a grading electrode is arranged at the two ends of a secondary aluminum radiator starting from the first end and the last end of the cathode valve section and the anode valve section, and the grading electrodes at the two ends are connected through an equipotential line. The application changes the grading electrode originally connected with the first end and the last end of the aluminum radiator to the position connected with the secondary aluminum radiator, and the leakage current of the grading electrode can be significantly reduced by changing the position of the grading electrode of the thyristor assembly, so that the fouling of the grading electrode is avoided.

Description

Technical Field

[0001] This application belongs to the field of power technology, and specifically relates to a water circuit of a converter valve cooling system for suppressing leakage current of the equalizing electrode. Background Technology

[0002] The converter valve is a core component of ultra-high voltage direct current (UHVDC) transmission projects. It connects three AC phases sequentially to the DC terminal to obtain the desired DC voltage and control the power. The thyristor assembly is the basic unit of the converter valve, and the thyristor is the core component. During operation, it generates heat; if the temperature exceeds the thyristor junction temperature, the thyristor will fail. Therefore, cooling is necessary. Figure 1 As shown, taking the existing thyristor assembly cooling water circuit as an example, the thyristor assembly consists of two valve sections connected in series, each valve section including 13 thyristors and corresponding accessories. This assembly adopts a parallel water circuit cooling system. The cathode and anode sides of each thyristor are in close contact with the aluminum heat sink. The inlet and outlet water pipes of each aluminum heat sink are connected to the manifold water circuit. The internal cooling water system carries away the heat generated by the thyristors during operation through the inlet and outlet manifold water pipes, multiple branch water circuits, and aluminum alloy heat sinks, thus achieving the purpose of cooling.

[0003] To prevent electrochemical corrosion of aluminum radiators, equalizing electrodes are typically installed in the cooling water circuit of the converter valve cooling system. An equalizing electrode is a cylindrical metal component with an arc-shaped end face, placed in the manifold of the cooling water inlet and outlet. Connecting adjacent aluminum radiators with the equalizing electrode ensures that the radiator's potential matches the potential at the corresponding location on the manifold, preventing leakage current from causing electrochemical corrosion on the radiator surface. This provides operational protection for the internal cooling water system. Installation location is detailed in [link to installation instructions]. Figure 1 However, in recent years, cooling water system failures have been frequent, causing huge economic losses. Inspection revealed that scaling on the equalizing electrode in the cooling water system within the converter valve is one of the main causes of these failures. Research indicates that the scaling products originate from corrosion of the aluminum radiator in the converter valve cooling system. The main component of the scaling is aluminum hydroxide, and the formation of this scale is due to the electric field force generated by the positive potential equalizing electrode under alkaline conditions attracting negatively charged ions Al(OH)4. - The positive potential is formed by a reaction on the electrode surface, and the positive potential is generated by the leakage current from the equalizing electrode to ground. Therefore, controlling the generation of leakage current will effectively prevent scale formation on the equalizing electrode. Summary of the Invention

[0004] This application provides a water circuit for a converter valve cooling system that suppresses leakage current of the equalizing electrode, so as to at least solve the problem of frequent failures in the current converter valve cooling water circuit system caused by the structure of the equalizing electrode.

[0005] According to this application, a water circuit for a converter valve cooling system that suppresses leakage current of the equalizing electrode is provided, comprising:

[0006] An anode valve section, a cathode valve section, and a cooling water pipe;

[0007] The anode valve section and the cathode valve section are respectively located on both sides of the cooling water pipe and are connected to the cooling water pipe;

[0008] Both the anode valve section and the cathode valve section contain several aluminum heat sinks connected in parallel;

[0009] The secondary aluminum heat sink, starting from the beginning and end of the cathode valve section and the anode valve section, is equipped with equalizing electrodes at both ends, which are connected by an equipotential line.

[0010] In one embodiment, the anode valve section includes a plurality of aluminum heat sinks connected in parallel, with thyristors disposed between the aluminum heat sinks.

[0011] In one embodiment, the cathode valve section includes a plurality of aluminum heat sinks connected in parallel, with thyristors disposed between the aluminum heat sinks.

[0012] In one embodiment, two manifolds extend from both sides of the cooling water pipe, namely an inlet manifold and an outlet manifold.

[0013] In one embodiment, the inlet manifold is connected to the inlet branch pipe of the aluminum radiator.

[0014] In one embodiment, the water outlet manifold is connected to the water outlet branch pipe of the aluminum radiator.

[0015] In one embodiment, the cathode valve section and the anode valve section each contain 14 aluminum heat sinks.

[0016] In one embodiment, the two valve sections form a 6-pulse current converter with a common cathode and a common anode conduction configuration.

[0017] In one embodiment, the voltage equalization electrodes of each phase thyristor follow the same potential change pattern over a 2π cycle.

[0018] In one embodiment, the 6-pulse current converter is composed of basic unit thyristors connected in series and parallel.

[0019] This application can significantly reduce the leakage current of the equalizing electrode by changing the position of the equalizing electrode of the thyristor assembly, thereby avoiding scaling of the equalizing electrode. Compared with the prior art, it can completely avoid the leakage current to ground when the AC power supply is unloaded; completely avoid the leakage current to ground formed at the junction of valve section 1 and valve section 2 of the thyristor assembly when one valve section is turned on to the other valve section; and completely avoid the leakage current to ground formed on the cathode side and anode side of the other two phases when one phase of the three-phase thyristor a, b, and c is turned on. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of an existing internal cooling water valve assembly.

[0022] Figure 2 This is a schematic diagram of the internal cooling water valve assembly after the position of the equalizing electrode has been changed, as provided in this application.

[0023] Figure 3 This is a schematic diagram of the original 2π cycle valve segment switching and the leakage current of the equalizing electrode.

[0024] Figure 4 This is a schematic diagram of a leakage circuit dominated by the A and B phase AC power supply, with the original phase angle being 0 to 1π / 3.

[0025] Figure 5 This is the leakage circuit diagram of the original a-phase thyristor assembly under no-load conditions during one 2π cycle.

[0026] Figure 6 This is a schematic diagram of the valve segment switching and equalizing electrode leakage current after the modification of this application for a 2π cycle.

[0027] Figure 7 This is a schematic diagram of the leakage circuit dominated by the phase angle 0 to 1π / 3A and phase B AC power supply after the modification in this application.

[0028] Figure 8 This is a schematic diagram illustrating the resistors R0 and R1 and grounding in a quadruple valve tower. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Currently available cooling methods for thyristor assemblies include Siemens' parallel water cooling system, ABB's series water cooling system, and Areva's series-parallel water cooling system, etc. The equalizing electrodes are all connected to the heat sinks at the beginning and end of the anode and cathode valve sections, such as... Figure 1 As shown.

[0031] However, according to the principle of a 12-pulse direct-path current converter, it is equivalent to two 6-pulse current converters connected in series with a phase difference of 1 / 6π phase angle. A 6-pulse current converter is composed of basic unit thyristor assemblies connected in series and parallel. The two valve sections of the thyristor assembly (such as...) Figure 1 As shown, a 6-pulse current converter is formed using a common cathode and common anode conduction method. This is because the rectifier transformer neutral point is grounded and the equalizing electrodes are connected to the grounding terminal via a water circuit (e.g., Figure 8 As shown in the diagram, this creates a current conduction loop between the two grounding points, resulting in current leakage between the equalizing electrode and the ground. Therefore, based on the principle of the six-pulse current converter and the schematic diagram of the thyristor assembly cooling water flow... Figure 1 This application provides a schematic diagram of an equivalent circuit for the switching of inter-valve current conduction and the leakage current of the equalizing electrode during a 2π-cycle period. Figure 3 , Figure 3 In the diagram, a, b, and c represent thyristor assemblies with different phases; Ф a Ф a1 、-Ф a 、-Ф a1 Ф b Ф b1 、-Ф b 、-Ф b1 Ф c Ф c1 、-Ф c 、-Ф c1 , which represents the equalizing electrode potential formed by the three-phase AC power supply A, B, and C in the anode valve section 1 and the equalizing electrode potential formed in the cathode valve section 2.

[0032] The potential formed by the equalizing electrode is highly consistent with that of the aluminum heat sink. From the equivalent circuit... Figure 3 It can be seen that during one 2π cycle switching process of the valve segment, due to the series connection at the junction of the first and last aluminum heat sinks of the a, b, and c three-phase thyristor assemblies, both the anode and cathode sides of the thyristor assemblies form the same potential as the conducting valve segment, and leakage current exists in the connected equalizing electrodes. The series connection at the junction of the anode side aluminum heat sink of valve segment 1 and the cathode side aluminum heat sink of valve segment 2 in the thyristor assembly also has a series effect, so both aluminum heat sinks in valve segment 1 and valve segment 2 will form equipotential. When one aluminum heat sink is energized, the equalizing electrode connected to the other aluminum heat sink will also have leakage current. Table 1 below shows the equivalent circuit within one 2π cycle. Figure 8 Statistics on the potentials of each equalizing electrode.

[0033] Table 1 shows the voltage equalization electrode potentials of a three-phase thyristor assembly (a, b, c) in a 2π cycle.

[0034]

[0035] As shown in Table 1, the voltage equalization electrodes of each phase thyristor assembly follow the same potential change pattern within a 2π cycle. Taking the a-phase thyristor as an example, the voltage equalization electrode potential on the cathode side of valve section 1 is Ф. a1 Ф b1 Ф c1 The duration is 2π / 3 for each period; the anode side potential of valve section 1 is Ф. a The duration is π, -Ф a The duration is π; the cathode side potential of valve section 2 is Ф. a The duration is π, -Ф a The duration is π; the anode potential of valve section 2 is -Ф. a1 、-Ф b1 、-Ф c1 Each duration is 2π / 3.

[0036] 1. Leakage current dominated by the positive AC power supply of phase A during the 0 to 1π / 3 time period:

[0037] Leakage current on the cathode side of phase b and c valve section 1:

[0038] Leakage current (electrolysis current) on the cathode side of phase a valve section 1:

[0039] Leakage current on the anode side of phase a valve section 1:

[0040] Leakage current on the cathode side of phase a valve section 2:

[0041] 2. Leakage current dominated by the negative AC power supply of phase B during the 0–1π / 3 time period:

[0042] Leakage current on the anode side of phase a and c valve section 2:

[0043] Leakage current (electrolysis current) on the anode side of phase b valve section 2:

[0044] Leakage current on the cathode side of phase b valve section 2:

[0045] Leakage current on the anode side of phase b valve section 1:

[0046] 3. Analysis of leakage current magnitude of voltage equalization electrodes at different potentials in a 2π-cycle thyristor assembly

[0047] From equivalent circuit Figure 3 , 4Analysis of ① and ② shows that within a 2π cycle, except for the 2π / 3 conduction angle, the leakage current formed by the equalizing electrodes on the cathode side of valve section 1 and the anode side of valve section 2 is the electrolytic current. The leakage currents dominated by the three-phase AC power supply (A, B, and C) are all leakage to the ground. The leakage current dominated by the positive AC power supply flows from the equalizing electrode to the ground, and the equalizing electrode forming the leakage current has a positive potential; the leakage current dominated by the negative AC power supply flows from the ground to the equalizing electrode, and the equalizing electrode forming the leakage current has a negative potential. Each AC power supply has a 2π / 3 period of no-load operation, of which 1π / 3 period forms a positive potential equalizing electrode between the anode and cathode valve sections, and the other 1π / 3 period forms a negative potential. This is because the scale ions Al(OH)4... - Due to its negative charge property, Al(OH)4, as a voltage equalizing electrode with a positive potential property, can be affected. - Since this process has an effect, this paper only counts the leakage current of the positive electrode, which is the voltage equalizing electrode. Taking the a-phase thyristor assembly as an example, let π be the time parameter.

[0048] Leakage current I1 on the cathode side of valve section 1:

[0049]

[0050] In formula (1), Q1 is the leakage current of the equalizing electrode on the cathode side of valve section 1 within a 2π cycle.

[0051]

[0052] Leakage current I from the anode side equalizing electrode of valve section 1 to ground 11 Electrolysis current I 12 :

[0053]

[0054] In the formula (3)Q 11 The leakage current to ground from the anode-side equalizing electrode of valve section 1 within a 2π cycle is represented by the italicized Ф. a The potential formed on the anode side of valve section 1 of the phase a thyristor assembly when the phase A AC power supply is unloaded (2π / 3~π) (see Figure 5 ).

[0055]

[0056] In the formula (4)Q 12 The leakage current of the anode side equalizing electrode in valve section 1 within a 2π cycle.

[0057]

[0058]

[0059] Leakage current I2 on the cathode side of valve section 2

[0060]

[0061] In formula (7), Q2 is the leakage current of the equalizing electrode on the cathode side of valve section 2 within one 2π cycle, and the italicized Ф a The potential formed on the cathode side of valve section 2 of the phase a thyristor assembly when the phase a AC power supply is unloaded (2π / 3~π) (see Figure 5 ).

[0062]

[0063] Leakage current I on the anode side of valve section 2 22

[0064]

[0065] In the formula (9)Q 22 The leakage current of the equalizing electrode on the anode side of valve section 2 within a 2π cycle.

[0066]

[0067] ④ Comparison of equalizing electrode potential and leakage current magnitude

[0068] Potential magnitude comparison: Ф a Ф b Ф c For AC power supplies, the effective value is the same, and the conduction angle is equal within the same cycle; similarly, Ф... a1 Ф b1 Ф c1 They are also equal. Ф a >Ф a1 Because the thyristor voltage drop is very small, the voltage drop in one valve section is generally around 25V when it is turned on (Ф). a -Ф a1 Therefore, Ф can be considered as a ≈Ф a1 ;Ф a The effective potential is calculated as 0 to 2π / 3, Ф a The potential is calculated as (2π / 3) to π, so Ф a >Ф a Comparison of water resistance values: see Figure 8 R1 is constant, and the magnitude of R0 is positively correlated with the distance from the grounding electrode.

[0069] Comparison of leakage current magnitudes:

[0070]

[0071] In the formula (12), R1 is the water resistance between the equalizing electrodes at the beginning and end of the valve section, and R0 is the water resistance between the inlet / outlet of the busbar water pipe and the ground. From the valve tower design, it can be known that R1 < R0. Substituting into the above formula, it is greater than 0. Therefore, the leakage current on the cathode side of valve section 1 is greater than that on the anode side. Similarly, because I2 = I 11 +I 12 , so I1 > I2.

[0072]

[0073] Taking a 500KV converter station as a reference in formula (12), Ф a is the effective value potential calculated from 0 to 2π / 3, and Ф a is the effective value voltage calculated from (2π / 3) to π. Therefore, Ф a +Ф a > 500KV. It can be seen that the leakage current of the equalizing electrode on the anode side of valve section 2 is much greater than the electrolytic current formed on the cathode side.

[0074] From the above calculations, it can be known that: among the leakage currents in the direction of the local 2π cycle, the leakage charge of the equalizing electrode on the cathode side of the thyristor component valve section 1 is the largest, followed by the equalizing electrodes on the cathode side of valve section 2 and the anode side of valve section 1; the leakage currents formed by the equalizing electrode on the anode side of valve section 1 (including the electrolytic current) and valve section 2 are equal, and the electrolytic current formed by the equalizing electrode on the anode side of valve section 2 is much smaller than the other leakage currents in the direction of the local; within a 2π / 3 commutation angle, the largest leakage current to the ground is the equalizing electrode on the cathode side of valve section 2. The positive potential equalizing electrode is affected by the pulsating electromotive force of the aluminum radiator, forming a positive electric potential and a pulsating electric field relative to the ground, and the field strength change is consistent with the six-pulse current fluctuation. In the electric field formed by the equalizing electrode, the negative ions (Al(OH)4 - ) are affected by the pulsating electric field force and move towards the equalizing electrode and form an electric deposition reaction on the electrode. The leakage current formed on the anode side of valve section 1 is the same as that on the cathode side of valve section 2, but the fouling is less than that on the cathode side of valve section 2. This is because within a 2π / 3 conduction angle, the leakage current formed on the anode side of valve section 1 has a DC component of electrolytic current, and the electrolytic current will generate oxygen (4OH - -4e - = 2H2O + O2), and the formed oxygen bubbles prevent the fouling of the Bayer process. The fouling on the anode side of valve section 1 is mainly formed during the no-load period of the AC power supply (see Figure 5However, the leakage current lasts only 1 / 3 of that on the cathode side of valve section 2, so the scale buildup is relatively small. The equalizing electrode on the anode side of valve section 2 forms a weak electric field, and electrolysis produces oxygen, preventing scale formation. While the equalizing electrode on the anode side of valve section 2 forms a weak electric field, and electrolysis produces oxygen, preventing scale formation, some DC converter stations have observed scale buildup on the anode side of valve section 2, though less than on the cathode side. This is because substations switch operation seasonally; substations primarily operating with rectifier transformers will switch to reverse transformer operation at certain times (the same applies to reverse converter stations), thus causing scale buildup on the anode side of valve section 2.

[0075] Scaling on the equalizing electrode is caused by the leakage current dominated by the positive AC power supply, while the leakage current dominated by the negative AC power supply cannot form scale. Electrolysis current does not produce scale and inhibits it. Over a period of time, the amount of scale depends on the magnitude of the leakage current and the intensity of the electric field formed by the equalizing electrode. In other words, the equalizing electrode with the largest leakage current forms a pulsating electric field that affects Al(OH)4. - Doing more work results in a larger amount of scale, which explains why the cathode of the equalizing electrode in rectifier converter stations has higher scale buildup than the anode of the equalizing electrode in countercurrent converter stations.

[0076] Therefore, this application provides a water circuit for a converter valve cooling system that suppresses leakage current of the equalizing electrode, such as... Figure 2 As shown, it includes:

[0077] An anode valve section, a cathode valve section, and a cooling water pipe;

[0078] The anode valve section and the cathode valve section are respectively located on both sides of the cooling water pipe and are connected to the cooling water pipe;

[0079] Both the anode valve section and the cathode valve section contain several aluminum heat sinks connected in parallel;

[0080] The secondary aluminum heat sink, starting from the beginning and end of the cathode valve section and the anode valve section, is equipped with equalizing electrodes at both ends, which are connected by an equipotential line.

[0081] The anode valve section consists of several aluminum heat sinks connected in parallel, with thyristors placed between the aluminum heat sinks.

[0082] The cathode valve section consists of several aluminum heat sinks connected in parallel, with thyristors placed between the aluminum heat sinks.

[0083] Two manifolds extend from both sides of the cooling water pipe, namely the inlet manifold and the outlet manifold.

[0084] The water inlet manifold is connected to the water inlet branch pipe of the aluminum radiator.

[0085] The water outlet manifold is connected to the water outlet branch pipe of the aluminum radiator.

[0086] The cathode valve section and the anode valve section each contain 14 aluminum heat sinks.

[0087] The two valve sections form a 6-pulse current converter with common cathode and common anode conduction.

[0088] Each phase thyristor voltage equalization electrode follows the same potential change pattern within a 2π cycle.

[0089] In one embodiment, the 6-pulse current converter is composed of basic unit thyristors connected in series and parallel.

[0090] Specifically, based on the principle of a 12-pulse direct-circuit current converter, it is equivalent to two 6-pulse current converters connected in series with a phase difference of 1 / 6π phase angle. A 6-pulse current converter is composed of basic unit thyristor assemblies connected in series and parallel. The two valve sections of the thyristor assembly (such as...) Figure 2 As shown, a 6-pulse current converter is formed using a common cathode and common anode conduction method. This is because the neutral point of the rectifier transformer is grounded and the voltage equalization electrode is connected to the grounding electrode through a water circuit (e.g. Figure 8 As shown in the diagram, this creates a current conduction loop between the two grounding points, resulting in current leakage between the equalizing electrode and the ground. Therefore, based on the principle of the six-pulse current converter and the schematic diagram of the thyristor assembly cooling water flow... Figure 2 This paper presents a schematic diagram of an equivalent circuit for the switching of inter-valve current and leakage current of the equalizing electrode with a 2π cycle. Figure 6 In the diagram, a, b, and c represent thyristor assemblies with different phases; Ф a Ф a1 、-Ф a 、-Ф a1 Ф b Ф b1 、-Ф b 、-Ф b1 Ф c Ф c1 、-Ф c 、-Ф c1 , which represents the equalizing electrode potential formed by the three-phase AC power supply A, B, and C in the anode valve section 1 and the equalizing electrode potential formed in the cathode valve section 2.

[0091] Table 2 shows the voltage equalization electrode potentials of the three-phase thyristor assemblies a, b, and c after one 2π cycle following the modification.

[0092]

[0093] As shown in Table 2, the voltage equalization electrodes of each phase thyristor assembly follow the same potential change pattern within a 2π cycle. Taking the a-phase thyristor as an example, the voltage equalization electrode potential on the cathode side of valve section 1 is Ф. a1 The duration is 2π / 3; the anode side potential of valve section 1 is Ф.a The duration is 2π / 3; the cathode side potential of valve section 2 is -Ф a The duration is 2π / 3; the anode potential of valve section 2 is -Ф. a1 The duration is 2π / 3. This paper is based on a schematic diagram of leakage in the equalizing electrode from 0 to 1π / 3. Figure 6 , 7 A schematic analysis of the leakage current magnitude is provided.

[0094] 1. Leakage current dominated by the positive AC power supply of phase A during the 0 to 1π / 3 time period:

[0095] Leakage current on the cathode side of phase b and c valve section 1: 0

[0096] Leakage current (electrolysis current) on the cathode side of phase a valve section 1:

[0097] Leakage current on the anode side of phase a valve section 1:

[0098] Leakage current on the cathode side of phase a valve section 2: 0

[0099] Leakage current on the anode side of phase valve section 2: 0

[0100] 2. Leakage current dominated by the negative AC power supply of phase B during the 0–1π / 3 time period:

[0101] Leakage current on the anode side of phase a and c valve section 2: 0

[0102] Leakage current (electrolysis current) on the anode side of phase b valve section 2:

[0103] Leakage current on the cathode side of phase b valve section 2:

[0104] Leakage current on the anode side of phase b valve section 1: 0

[0105] Leakage current on the cathode side of phase b valve section 1: 0

[0106] 3. Analysis of leakage current magnitude of voltage equalization electrodes at different potentials in a 2π-cycle thyristor assembly

[0107] From equivalent circuit Figure 6 , 7Analysis of ① and ② shows that within a 2π cycle, leakage current exists only within a 2π / 3 conduction angle. The leakage current formed by the equalizing electrodes on the cathode side of valve section 1 and the anode side of valve section 2 is the electrolytic current. The anode side of valve section 1 forms a leakage current to ground and an electrolytic current to the equalizing electrode on the cathode side of valve section 1. The equalizing electrode on the cathode side of valve section 2 forms a negative leakage current to ground and a negative electrolytic current to the equalizing electrode on the anode side of valve section 2. The leakage current dominated by the positive AC power supply flows from the equalizing electrode to the ground, and the equalizing electrode forming the leakage current is at a positive potential; the leakage current dominated by the negative AC power supply flows from the ground to the equalizing electrode, and the equalizing electrode forming the leakage current is at a negative potential. Each AC power supply does not form leakage current during the 2π / 3 time period's no-load period. This is because the scale ions Al(OH)4... - Due to its negative charge property, Al(OH)4, as a voltage equalizing electrode with a positive potential property, can be affected. - Therefore, this paper only analyzes the leakage of the voltage equalizing electrode with positive potential and the leakage of the voltage equalizing electrode with high potential in the electrolytic current. Taking the a-phase thyristor assembly as an example, let π be the time parameter.

[0108] Leakage current I from the anode side equalizing electrode of valve section 1 to ground 11 Electrolysis current I 12 :

[0109]

[0110] In the formula (1)Q 11 The leakage current to ground from the anode side equalizing electrode of valve section 1 within a 2π cycle.

[0111]

[0112] In the formula (4)Q 12 The leakage current of the anode side equalizing electrode in valve section 1 within a 2π cycle.

[0113]

[0114]

[0115] Leakage current I on the anode side of valve section 2 22

[0116]

[0117] In the formula (9)Q 22 The leakage current of the equalizing electrode on the anode side of valve section 2 within a 2π cycle.

[0118]

[0119] 6.3 Comparative Analysis of Implementation Method 1 and Implementation Method 2

[0120] As calculated from the above implementation method two, apart from the leakage current to ground on the anode side of valve section 1, the rest is electrolytic current. Furthermore, the anode side of valve section 1 includes a DC component of the electrolytic current. As analyzed in implementation method one, scale cannot form under electrolytic current. Therefore, the improved thyristor assembly completely overcomes the scaling problem of the equalizing electrode.

[0121] As can be seen from the analysis of the potential statistics of Implementation Method 2 in Table 2, the thyristor assembly with improved voltage equalization electrode position completely avoids current leakage when the AC power supply is unloaded; it completely avoids the leakage problem caused by the aluminum heat sinks at the beginning and end of the three-phase thyristor assemblies (a, b, and c) being connected by copper wires, where one phase thyristor assembly conducts and the other two phases are leaking current; and it completely avoids the leakage current formed at the junction of valve section 1 and valve section 2 of the thyristor assembly when one valve section is conducting, which affects the other valve section.

[0122] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the description of the method embodiments. In the description of this specification, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this specification. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, without contradiction, those skilled in the art can combine and integrate different embodiments or examples and features of different embodiments or examples described in this specification. The above descriptions are merely embodiments of the embodiments of this specification and are not intended to limit the embodiments of this specification. For those skilled in the art, the embodiments of this specification can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the embodiments in this specification shall be included within the scope of the claims of the embodiments in this specification.

Claims

1. A water circuit for a converter valve cooling system that suppresses leakage current in the equalizing electrode, characterized in that, include: An anode valve section, a cathode valve section, and a cooling water pipe; The anode valve section and the cathode valve section are respectively located on both sides of the cooling water pipe and are connected to the cooling water pipe; Both the anode valve section and the cathode valve section contain several aluminum heat sinks connected in parallel, and a thyristor is arranged between the aluminum heat sinks. A voltage equalization electrode is provided at both ends of the secondary aluminum heat sink starting from the first and last ends of the cathode valve section, and a voltage equalization electrode is provided at both ends of the secondary aluminum heat sink starting from the first and last ends of the anode valve section. The voltage equalization electrodes at both ends of each secondary aluminum heat sink are connected by an equipotential line. Two manifolds extend from both sides of the cooling water pipe, namely an inlet manifold and an outlet manifold. The water inlet manifold is connected to the water inlet branch pipe of the aluminum radiator; The water outlet manifold is connected to the water outlet branch pipe of the aluminum radiator.

2. The water circuit of the converter valve cooling system for suppressing leakage current of the equalizing electrode according to claim 1, characterized in that, The cathode valve section and the anode valve section each contain 14 aluminum heat sinks.

3. The water circuit of the converter valve cooling system for suppressing leakage current of the equalizing electrode according to claim 2, characterized in that, The two valve sections form a 6-pulse current converter with common cathode and common anode conduction.

4. The water circuit of the converter valve cooling system for suppressing leakage current of the equalizing electrode according to claim 3, characterized in that, Each phase thyristor voltage equalization electrode follows the same potential change pattern within a 2π cycle.

5. The water circuit of the converter valve cooling system for suppressing leakage current of the equalizing electrode according to claim 4, characterized in that, The 6-pulse current converter is composed of basic unit thyristors connected in series and parallel.

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