Hybrid power grid commutation converter

Abstract

The invention belongs to the technical field of ultra / extra-high voltage direct current transmission, and discloses a hybrid power grid commutation converter which comprises an integrated gate thyristor converter, and a main branch of the integrated gate thyristor converter comprises a first reactor assembly, an IGCT assembly and a second reactor assembly which are sequentially connected in series. According to the hybrid power grid commutation converter, free switching of positive and negative transmission of the electric power can be realized, the static, transmission and adjustment change of the electric power can be completed, the commutation failure problem is avoided, and the reliability is improved while the equipment cost is reduced. The hybrid power grid commutation converter provided by the invention meets the requirements of each operation condition in the operation process of an ultra / extra-high voltage direct current transmission system, and has the advantages of large on-state current, high blocking voltage, low on-state voltage drop, large turn-off current, relatively high switching speed, high reliability, bidirectional voltage bearing and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra / ultra-high voltage direct current transmission, and in particular relates to a hybrid power grid phase-commutation converter. Background Art

[0002] At present, the development of UHV DC transmission is the best solution to achieve optimal cross-regional energy allocation and accelerate the transformation of resource advantages into economic advantages.

[0003] There are two types of DC transmission technologies: line-commutated converter (LCC) and voltage source converter (VSC). Among them, LCC converter valves use thyristor technology. Thyristor is a semi-controlled device that can only be controlled to open but not closed. When a fault occurs on the inverter side of the DC transmission system, the thyristor converter valve has the risk of commutation failure.

[0004] Commutation failure is a relatively serious fault in the DC transmission system. Theoretically, any fault in the power system may lead to commutation failure. A single commutation failure will cause a voltage drop, current increase, and reduced transmission power for several cycles. It may not have much impact on civilian electricity, but for a multi-terminal DC feed-in transmission system, once a commutation failure occurs, it will not only cause a sudden drop in transmission power, but also cause a power outage in the large power grid in severe cases. The commutation failure problem affects the planning and development of UHV DC transmission systems.

[0005] There are many research directions for the problem of commutation failure, which can be divided into two categories. One is to optimize the control strategy in order to enhance the system's ability to resist commutation failure from the secondary side; the other is to study the commutation equipment, including capacitor commutated converter (CCC), controlled series capacitor converter (CSCC) and new converters based on semi-controlled H-bridge modules. However, these control strategies and the switching of commutation equipment need to be based on accurate and timely predictive control systems. Through real-time monitoring of current and voltage, possible commutation failures can be predicted to adjust the control strategy or control the switching of capacitors. However, existing prediction systems have a certain delay, and the prediction of commutation failure is not advanced, and there is a possibility of misjudgment. The commutation failure resistance measures that rely on predictions are often not very effective.

[0006] Flexible DC transmission technology can suppress the commutation failure of the thyristor valve on the inverter side. It adopts the technical route of voltage source converter, but the one-time investment is too large, the equipment occupies a large area and has high costs, the economy is poor, and the reliability is not as good as the thyristor valve. At present, only the demonstration project in China uses LCC on the rectifier side and VSC on the inverter side in a hybrid DC mode. However, this transmission technology can only realize unidirectional power transmission and cannot complete power reversal.

[0007] Therefore, a commutation converter with stronger robustness and higher reliability for suppressing commutation failure is needed. Summary of the invention

[0008] In view of the above problems, the present invention provides a hybrid grid phase-commutation converter, which adopts the following technical solutions:

[0009] A hybrid grid commutation converter comprises an integrated gate thyristor converter, wherein a main branch of the integrated gate thyristor converter comprises a first reactor component, an IGCT component and a second reactor component which are sequentially connected in series.

[0010] Furthermore, the IGCT assembly includes a plurality of IGCT stages connected in series.

[0011] Furthermore, each of the IGCT stages includes an IGCT device, a resistor R1 and a first buffer circuit, and the IGCT device is connected in parallel with the first buffer circuit and the resistor R1.

[0012] Furthermore, it also includes a converter lightning arrester connected in parallel with the integrated gate thyristor converter.

[0013] Furthermore, the integrated gate thyristor converter further comprises a plurality of first auxiliary branches, each of the first auxiliary branches is connected in parallel with a plurality of the IGCT stages, and the first auxiliary branches comprise a series-connected IGCT component fuse and an IGCT component MOV.

[0014] Furthermore, the integrated gate thyristor converter further includes a second auxiliary branch, the second auxiliary branch is connected in parallel with the IGCT component, and the second auxiliary branch includes a first MOV component.

[0015] Furthermore, the integrated gate thyristor converter further includes a third auxiliary branch, the third auxiliary branch is connected in parallel with the IGCT component, and the third auxiliary branch includes a second MOV component and a first absorption capacitor component connected in series.

[0016] Furthermore, the integrated gate thyristor converter also includes a fourth auxiliary branch, which is connected in parallel with the IGCT component, and the fourth auxiliary branch includes an anti-parallel thyristor component, a current limiting resistor component and a second absorption capacitor component which are sequentially connected in series.

[0017] Furthermore, the integrated gate thyristor converter further includes a fifth auxiliary branch, the fifth auxiliary branch is connected in parallel with the IGCT component, and the fifth auxiliary branch includes a bypass switch component.

[0018] Furthermore, the hybrid grid-commutated converter further comprises a half-controlled converter, wherein a main branch of the half-controlled converter is connected in series with a main branch of the integrated gate thyristor converter.

[0019] Furthermore, the semi-controlled converter comprises a third electric controller component, a thyristor component and a fourth reactor component which are sequentially connected in series.

[0020] Furthermore, the thyristor assembly includes a plurality of thyristor stages connected in series, each of the thyristor stages includes a thyristor device, a resistor R2 and a second buffer circuit, and the thyristor device is connected in parallel with the resistor R2 and the second buffer circuit.

[0021] Beneficial effects of the present invention:

[0022] 1. The hybrid grid commutation converter of the present invention can realize the free switching of forward and reverse transmission of electric power, can complete the static, transmission and regulation changes of electric power, and has no commutation failure problem, thereby reducing equipment cost and improving reliability.

[0023] 2. The hybrid grid-commutating converter of the present invention meets the requirements of various operating conditions during the operation of the ultra-high / ultra-high voltage direct current transmission system, and has the advantages of large on-state current, high blocking voltage, low on-state voltage drop, large shut-off current, high switching speed, high reliability and bidirectional pressure bearing.

[0024] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A topological schematic diagram of a main flow branch of a hybrid grid-commutated converter according to an embodiment of the present invention is shown;

[0027] Figure 2A topological schematic diagram of a hybrid grid-commutated converter having a first auxiliary branch according to an embodiment of the present invention is shown;

[0028] Figure 3 A topological schematic diagram of a hybrid grid-commutated converter having a second auxiliary branch according to an embodiment of the present invention is shown;

[0029] Figure 4 A topological schematic diagram of a hybrid grid-commutated converter having a third auxiliary branch according to an embodiment of the present invention is shown;

[0030] Figure 5 A topological schematic diagram of a hybrid grid-commutated converter having a fourth auxiliary branch according to an embodiment of the present invention is shown;

[0031] Figure 6 A topological schematic diagram of a hybrid grid-commutated converter having a fifth auxiliary branch according to an embodiment of the present invention is shown;

[0032] Figure 7 A topological schematic diagram of a hybrid grid-commutated converter having an integrated gate thyristor converter and a half-controlled converter according to an embodiment of the present invention is shown.

[0033] In the figure: 1. integrated gate thyristor converter; 2. first reactor assembly; 3. IGCT assembly; 4. second reactor assembly; 5. IGCT stage; 6. converter arrester; 7. IGCT assembly fuse; 8. IGCT assembly MOV; 9. first MOV assembly; 10. second MOV assembly; 11. first absorption capacitor assembly; 12. anti-parallel thyristor assembly; 13. current limiting resistor assembly; 14. second absorption capacitor assembly; 15. bypass switch assembly; 16. half-controlled converter; 17. third electric controller assembly; 18. thyristor assembly; 19. fourth reactor assembly; 20. thyristor stage. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0035] It should be noted that the terms "first", "second", etc. in the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0036] like Figure 1As shown, a hybrid grid-commutated converter (HCC) includes an integrated gate thyristor converter 1, and the main current branch of the integrated gate thyristor converter 1 includes a first reactor component 2, an IGCT (Intergrated Gate Commutated Thyristors, integrated gate commutated thyristors) component and a second reactor component 4 connected in series in sequence, wherein the IGCT component 3 is a component in the valve structure that can be replaced as a whole during maintenance, including a plurality of IGCT stages 5 connected in series and a mechanical combination of auxiliary equipment close to the IGCT stage 5, but does not include a reactor component.

[0037] The hybrid grid commutation converter of the embodiment of the present invention is a complete combined electronic switch device that can be controlled or uncontrolled to operate. Under normal circumstances, it conducts electricity in only one direction (forward direction) and can realize the function of a commutation arm in a commutation bridge.

[0038] The hybrid grid-commutated converter of the embodiment of the present invention is a converter realized based on integrated gate-commutated thyristors and has the advantages of large on-state current, high blocking voltage, low on-state voltage drop, large shut-off current, high switching speed, high reliability and bidirectional pressure bearing.

[0039] In addition, the hybrid converter based on IGCT devices can not only realize the free switching of forward and reverse transmission of electric power, but also complete the static, transmission and regulation changes of electric power, and has no phase change failure problem. It reduces the equipment cost and improves the reliability at the same time, which is of great significance for the construction of new power grids and the research of new power systems.

[0040] The hybrid grid-commutated converter of the embodiment of the present invention meets the operating condition requirements during the operation of the ultra-high / ultra-high voltage direct current transmission system, including starting operating conditions, locking operating conditions, fault process resistance to commutation failure conditions, maximum continuous triggering voltage conditions, maximum continuous recovery voltage conditions, maximum transient operating load conditions (triggering angle 90°) operating conditions, minimum delay angle conditions, minimum shutdown angle conditions, transient undervoltage conditions, intermittent DC current conditions and fault surge high current conditions.

[0041] For example, the first reactor assembly 2 and the second reactor assembly 4 each include a mechanical combination of a single or a plurality of reactors.

[0042] like Figure 1 As shown, for example, each IGCT stage 5 includes an IGCT device S, a resistor R1, a first buffer circuit, auxiliary equipment close to the IGCT device S, and an inductor, wherein the IGCT device S includes a single integrated gate thyristor or a plurality of integrated gate thyristors connected in parallel; the IGCT device S is connected in parallel with the first buffer circuit and the resistor R1, for example, the first buffer circuit includes a resistor R2 and a capacitor C1 connected in series.

[0043] Among multiple IGCT stages 5 connected in series, the anode of the IGCT device S of the first IGCT stage 5 is connected to the first reactor assembly 2, the cathode of the IGCT device S of the last IGCT stage 5 is connected to the second reactor assembly 4, and the anode of the IGCT device S of the latter IGCT stage 5 among the intermediate multiple IGCT stages 5 is connected to the cathode of the IGCT device S of the previous IGCT stage 5.

[0044] like Figure 2 As shown, for example, the integrated gate thyristor converter 1 further includes a converter arrester 6 and a plurality of first auxiliary branches, wherein the converter arrester 6 is connected in parallel with the hybrid grid commutation converter, each first auxiliary branch is connected in parallel with a plurality of IGCT stages 5, the first auxiliary branch includes a series-connected IGCT component fuse 7 and an IGCT component MOV8 (meta loxide varistor), and the first auxiliary branch is used to cause the fuse to blow within a specified time after the IGCT component MOV8 continues to flow current.

[0045] like Figure 3 As shown, for example, the integrated gate thyristor converter 1 also includes a second auxiliary branch, which is connected in parallel with the IGCT component 3. The second auxiliary branch includes a first MOV component 9, which is connected in parallel across multiple IGCT stages 5 and is used to suppress the component voltage within the residual voltage range of the arrester when the IGCT component 3 is turned off.

[0046] like Figure 4 As shown, for example, the integrated gate thyristor converter 1 further includes a third auxiliary branch, which is connected in parallel with the IGCT component 3. The third auxiliary branch includes a second MOV component 10 and a first absorption capacitor component 11 connected in series. The third auxiliary branch is used for suppressing the rapid rise rate and amplitude of the component voltage by the amplitude branch current after the MOV reaches the action voltage when the IGCT component 3 is turned off.

[0047] like Figure 5 As shown, for example, the integrated gate thyristor converter 1 also includes a fourth auxiliary branch, which is connected in parallel with the IGCT component 3. The fourth auxiliary branch includes an anti-parallel thyristor component 12, a current limiting resistor component 13 and a second absorption capacitor component 14 connected in series in sequence. The fourth auxiliary branch is used to suppress the rapid rise rate of the component voltage when the IGCT component 3 is turned off.

[0048] For example, the anti-parallel thyristor assembly 12 includes a first thyristor and a second thyristor connected in parallel, wherein the anode of the first thyristor is connected to the cathode of the second thyristor, the first reactor assembly 2 and the anode of the IGCT device of the first IGCT stage 5, and the cathode of the first thyristor is connected to the anode of the second thyristor and one end of the current limiting resistor assembly 13.

[0049] like Figure 6 As shown, for example, the integrated gate thyristor converter 1 further includes a fifth auxiliary branch, which is connected in parallel with the IGCT component 3 . The fifth auxiliary branch includes a bypass switch component 15 . The fifth auxiliary branch is used to cut off the IGCT component 3 when the IGCT component 3 is abnormal.

[0050] like Figure 7 As shown, for example, the hybrid grid-commutated converter further includes a half-controlled converter 16, wherein the main branch of the half-controlled converter 16 is connected in series with the main branch of the integrated gate thyristor converter 1, thereby forming a hybrid converter valve main flow branch.

[0051] For example, the half-controlled converter 16 includes a third electric controller component 17, a thyristor component 18 and a fourth reactor component 19 connected in series in sequence, wherein the thyristor component 18 includes a plurality of thyristor stages 20 connected in series, each thyristor stage 20 includes a thyristor device T, a resistor R3 and a second buffer circuit, the thyristor device T is connected in parallel with the resistor R3 and the second buffer circuit, for example, the second buffer circuit includes a resistor R4 and a capacitor C2 connected in series.

[0052] Among them, among the multiple thyristor stages 20 connected in series, the anode of the thyristor device of the first thyristor stage 20 is connected to the second end of the third inductor assembly, the first end of the third electric controller assembly 17 is connected to the second inductor assembly 4, the cathode of the thyristor device of the last thyristor stage 20 is connected to the fourth inductor assembly 19, and the anode of the thyristor device of the latter thyristor stage 20 in the middle multiple thyristor stages 20 is connected to the cathode of the thyristor device of the previous thyristor stage 20.

[0053] The third reactor assembly and the fourth reactor assembly 19 each include a mechanical combination of a single reactor or a plurality of reactors.

[0054] The hybrid grid-commutated converter of the present invention can be applied to the field of ultra-high / ultra-high voltage power transmission, and can comprehensively and effectively promote the technological progress and development in the field of ultra-high / ultra-high voltage power transmission. It will gradually replace the semi-controlled LCC converter and become an indispensable high-power converter for the construction of new power systems.

[0055] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hybrid grid-commutated converter, characterized in that: It comprises an integrated gate thyristor converter (1), wherein a main branch of the integrated gate thyristor converter (1) comprises a first reactor component (2), an IGCT component (3) and a second reactor component (4) which are connected in series in sequence.

2. The hybrid grid-commutated converter according to claim 1, characterized in that: The IGCT assembly (3) comprises a plurality of IGCT stages (5) connected in series.

3. The hybrid grid-commutated converter according to claim 2, characterized in that: Each of the IGCT stages (5) comprises an IGCT device, a resistor R1 and a first buffer circuit, wherein the IGCT device is connected in parallel with the first buffer circuit and the resistor R1.

4. The hybrid grid-commutated converter according to claim 1, characterized in that: It also includes a converter lightning arrester (6) connected in parallel with the integrated gate thyristor converter (1).

5. The hybrid grid-commutated converter according to claim 2, characterized in that: The integrated gate thyristor converter (1) further comprises a plurality of first auxiliary branches, each of which is connected in parallel with a plurality of IGCT stages (5), and the first auxiliary branch comprises an IGCT component fuse (7) and an IGCT component MOV (8) connected in series.

6. The hybrid grid-commutated converter according to claim 1, characterized in that: The integrated gate thyristor converter (1) further comprises a second auxiliary branch, the second auxiliary branch is connected in parallel with the IGCT component (3), and the second auxiliary branch comprises a first MOV component (9).

7. The hybrid grid-commutated converter according to claim 1, characterized in that: The integrated gate thyristor converter (1) further comprises a third auxiliary branch, the third auxiliary branch being connected in parallel with the IGCT component (3), the third auxiliary branch comprising a second MOV component (10) and a first absorption capacitor component (11) connected in series.

8. The hybrid grid-commutated converter according to claim 1, characterized in that: The integrated gate thyristor converter (1) further comprises a fourth auxiliary branch, the fourth auxiliary branch being connected in parallel with the IGCT component (3), the fourth auxiliary branch comprising an anti-parallel thyristor component (12), a current limiting resistor component (13) and a second absorption capacitor component (14) which are sequentially connected in series.

9. The hybrid grid-commutated converter according to claim 1, characterized in that: The integrated gate thyristor converter (1) further comprises a fifth auxiliary branch, the fifth auxiliary branch being connected in parallel with the IGCT component (3), and the fifth auxiliary branch comprising a bypass switch component (15).

10. The hybrid grid-commutated converter according to any one of claims 1 to 9, characterized in that: The hybrid grid commutation converter further comprises a half-controlled converter (16), wherein a main branch of the half-controlled converter (16) is connected in series with a main branch of the integrated gate thyristor converter (1).

11. The hybrid grid-commutated converter according to claim 10, characterized in that: The semi-controlled converter (16) comprises a third electric controller component (17), a thyristor component (18) and a fourth reactor component (19) which are sequentially connected in series.

12. The hybrid grid-commutated converter according to claim 11, characterized in that: The thyristor assembly (18) comprises a plurality of thyristor stages (20) connected in series, each of the thyristor stages (20) comprising a thyristor device, a resistor R2 and a second buffer circuit, the thyristor device being connected in parallel with the resistor R2 and the second buffer circuit.

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