CN105262125B - Hybrid HVDC Topology System - Google Patents

Abstract

The invention relates to a hybrid direct-current transmission topological system which comprises a rectification side converter station and an inversion side converter station connected with the rectification side converter station, wherein the rectification side converter station comprises a rectification side converter transformer and a power grid phase-change converter, the inversion side converter station comprises a modular multilevel converter adopting a full-bridge submodule topology or a hybrid of the full-bridge submodule topology and a half-bridge submodule topology, and the inversion side converter transformer connected with the modular multilevel converter. This hybrid direct current transmission topological system can be on traditional direct current transmission system's basis, through replacing contravariant side electric wire netting phase change type transverter for adopting full-bridge submodule piece topology or full-bridge submodule piece topology and half-bridge submodule piece topology mixed modularization multilevel transverter, reforms transform traditional direct current transmission system into flexible direct current converter station to form hybrid direct current topology. Through the mode of reforming transform on traditional direct current transmission system's basis, can make full use of by the traditional direct current transmission primary equipment of reforming end, reduce the quantity of extra purchasing equipment, shorten the transformation time limit for a project, reduce cost.

Description

Hybrid HVDC Topology System

technical field

The invention relates to the technical field of direct current transmission systems, in particular to a hybrid direct current transmission topology system.

Background technique

At present, the HVDC transmission system mainly includes the traditional HVDC transmission system based on grid commutation technology (LCC-HVDC) and the flexible HVDC transmission system based on voltage source converter (VSC-HVDC). The traditional DC transmission system has large transmission capacity and low cost, but it has disadvantages such as easy commutation failure on the inverter side and strong dependence on the AC system. The flexible DC transmission system can independently adjust active power and reactive power, and has superior controllability and flexibility. It can effectively solve the problems of relatively insufficient local power support and weak voltage stability of the receiving end grid. However, the cost of flexible DC is relatively high. , and the loss is relatively high. Therefore, hybrid direct current transmission, which combines the advantages of traditional direct current transmission and flexible direct current transmission, has engineering application prospects.

There is a big difference between flexible DC and traditional DC in circuit structure and working principle, which leads to great differences in the primary equipment of its AC field and DC field. The primary equipment of the flexible DC side of the traditional hybrid DC transmission topology is designed using the principle of the flexible DC transmission system, so it still has the disadvantages of high cost of flexible DC and relatively high loss.

Contents of the invention

Based on this, it is necessary to provide a low-cost hybrid direct current transmission topology system for the above problems.

A hybrid direct current transmission topology system, comprising a rectification-side converter station and an inverter-side converter station connected to the rectification-side converter station,

The rectification-side converter station includes a rectification-side converter transformer and a grid commutation converter, and the grid commutation converter is connected to the rectification-side converter transformer and the inverter-side converter station; the rectification The side converter transformer is connected to the alternating current for voltage transformation processing and then output to the grid commutation converter, and the grid commutation converter rectifies the transformed alternating current to obtain direct current and transmits it to the inverter side converter flow station;

The inverter-side converter station includes a modular multilevel converter adopting a full-bridge sub-module topology or a mixture of a full-bridge sub-module topology and a half-bridge sub-module topology, and connecting the modular multi-level converter The converter transformer on the inverter side of the converter, the modular multilevel converter is connected to the grid commutation converter, converts the DC power delivered by the grid commutation converter to obtain AC power and transmits it to the An inverter-side converter transformer, which transforms the received AC power before outputting it.

The above-mentioned hybrid DC power transmission topology system includes a rectification-side converter station and an inverter-side converter station connected to the rectification-side converter station. The rectification-side converter station includes a rectification-side converter transformer and a grid commutation converter. The converter station includes modular multilevel converters with full-bridge sub-module topology or a mix of full-bridge and half-bridge sub-module topologies, and inverter-side converters connected to the modular multi-level converters transformer. The hybrid DC power transmission topology system can be based on the traditional DC power transmission system, by replacing the grid commutation converter on the inverter side with a full-bridge sub-module topology or a mixture of full-bridge sub-module topology and half-bridge sub-module topology. The modular multilevel converter retains the converter transformer on the inverter side of the traditional DC transmission system and transforms the traditional DC transmission system into a flexible DC converter station, thus forming a hybrid DC topology. By retrofitting on the basis of the traditional DC transmission system, it is possible to make full use of the traditional DC transmission primary equipment at the transformed end, reduce the number of additional purchased equipment, shorten the renovation period, and reduce costs.

Description of drawings

Fig. 1 is a structural diagram of a hybrid direct current transmission topology system in an embodiment;

Fig. 2 is a schematic diagram of a hybrid direct current transmission topology system in an embodiment;

3 is a schematic diagram of a hybrid direct current transmission topology system in another embodiment;

Fig. 4 is a schematic diagram of a hybrid direct current transmission topology system in yet another embodiment;

5 is a schematic diagram of a hybrid direct current transmission topology system in yet another embodiment;

Fig. 6 is a schematic diagram of a modular multilevel converter in an embodiment;

7 is a schematic diagram of a full-bridge submodule in an embodiment;

FIG. 8 is a schematic diagram of a half-bridge sub-module in an embodiment.

detailed description

A hybrid DC power transmission topology system, as shown in FIG. 1 , includes a rectification-side converter station 100 and an inverter-side converter station 200 connected to the rectification-side converter station 100 .

The rectification-side converter station 100 includes a rectification-side converter transformer 110 and a grid-commutated converter 120 , and the grid-commutated converter 120 is connected to the rectification-side converter transformer 110 and the inverter-side converter station 200 . The converter transformer 110 on the rectification side is connected to the AC power for transformation processing and then output to the grid commutation converter 120. The grid commutation converter 120 rectifies the transformed AC power to obtain DC power and transmits it to the inverter side converter station 200.

The inverter-side converter station 200 includes a modular multilevel converter 210 adopting a full-bridge sub-module topology or a mixture of a full-bridge sub-module topology and a half-bridge sub-module topology, and connecting modular multi-level converters The converter transformer 220 on the inverter side of 210, that is, the modular multilevel converter 210 in this embodiment can adopt a full-bridge sub-module topology, or a hybrid structure of a full-bridge sub-module topology and a half-bridge sub-module topology. The modular multilevel converter 210 is connected to the grid commutation converter 120, converts the DC power delivered by the grid commutation converter 120 to obtain AC power, and sends it to the inverter transformer 220 on the inverter side, and the inverter transformer 220 on the inverter side 220 transforms the received AC power and then outputs it.

Through the transformation of the DC transmission system, the commutation-type converter of the grid on the inverter side is replaced by a modular multi-level converter 210, thereby transforming the traditional DC converter station into a flexible DC converter station, saving the construction of hybrid DC The cost of the transmission system. The direct current transmission system in this embodiment is an overhead line direct current transmission system adopting a bipolar structure, and the voltage level may be ultra-high voltage or ultra-high voltage. Specifically, each pole of the inverter-side converter station 200 is composed of two or more modular multilevel converters 210, which can reduce the requirements on the flow capacity of the flexible DC converter and reduce the manufacturing difficulty and manufacturing cost.

In one embodiment, as shown in FIG. 2 , the grid commutation converter 120 is a twelve-pulse bridge converter composed of half-controlled power semiconductors, and each twelve-pulse bridge converter is composed of Two six-pulse bridge converters are connected in series. The use of the twelve-pulse bridge converter can simplify the filter device and save the cost of the converter station. In this embodiment, the semi-controlled power semiconductor is specifically a thyristor, which is simple in operation, high in reliability and low in cost. It can be understood that in other embodiments, the grid-commutated converter 120 may also be other types of converters, and the specific components may also be different.

In one of the embodiments, referring to FIG. 2 , the full-bridge sub-module topology of the modular multilevel converter 210 is composed of a fully-controlled power semiconductor that can be turned off and an energy storage capacitor that can output positive levels, The topology structure of negative level and zero level improves the stability and applicability of the modular multilevel converter 210 . The half-bridge sub-module topology of the modular multilevel converter 210 is a topological structure composed of fully-controlled power semiconductors that can be turned off and energy storage capacitors, and can output positive and zero levels. The full-bridge sub-module topology and the half-bridge sub-module topology of the modular multi-level converter 210 are mixed into a modular multi-level converter 210. There are a certain number of full-bridge sub-modules and a certain number of The topological structure of the half-bridge sub-module reduces the cost and cost of the modular multilevel converter 210 . Replacing the grid-commutated converter on the inverter side with a modular multilevel converter 210 refers to replacing each six-pulse bridge converter with a modular multilevel converter 210 . In this embodiment, the fully-controlled power semiconductors that can be turned off include insulated gate bipolar transistors, integrated gate commutation thyristors, turn-off thyristors, power field effect transistors, electron injection enhanced gate transistors, gate commutation thyristors and At least one of silicon carbide enhancement mode junction field effect transistors. The specific type can be selected according to the actual situation, and the applicability is high.

In one embodiment, the hybrid direct current transmission topology system further includes a direct current overhead line 300 , and the grid commutation converter 120 is connected to the modular multilevel converter 210 through the direct current overhead line 300 . The direct current is transmitted through the direct current overhead line 300, which has the advantages of simple structure, low line cost, high corridor utilization rate, small operation loss, convenient maintenance and meeting the requirements of large-capacity and long-distance power transmission.

Further, the inverter-side converter station 200 also includes an AC wall bushing and a DC wall bushing, and the modular multilevel converter 210 is connected to the inverter-side converter transformer 220 through the AC wall bushing. The DC wall bushing is connected to the DC overhead line 300 . In addition, the rectification-side converter station 100 also includes a rectification-side ground electrode connected to the grid commutation converter 120 , and the inverter-side converter station 200 also includes an inverter-side ground electrode connected to the block multilevel converter 210 . Through the transformation of the inverter side, the grid commutation converter of the inverter side converter station 200 is replaced by the modular multilevel converter 210, and the modular multilevel The connection mode of the DC transformer 220 remains unchanged, and the connection mode of the modular multilevel converter 210 and the ground electrode remains unchanged.

In one embodiment, as shown in FIG. 2 and FIG. 4 , both the rectifying-side converter transformer 110 and the inverter-side converter transformer 220 are double-winding transformers. In another embodiment, as shown in FIG. 3 and FIG. 5 , both the rectifying-side converter transformer 110 and the inverter-side converter transformer 220 may also be three-winding transformers.

Specifically, the hybrid DC transmission topology system shown in Figure 2 uses a three-winding converter transformer, and the DC transmission voltage level is ultra-high voltage. Each pole of the rectification-side converter station 100 is composed of a twelve-pulse bridge converter. Each twelve-pulse bridge converter is composed of two six-pulse bridge converters in series, and the two six-pulse bridge converters are connected to the AC system through a three-winding transformer on the AC side. By replacing the six-pulse bridge converter of the inverter side converter station 200 with a modular multilevel converter 210 using a full-bridge sub-module or a mixture of a full-bridge sub-module topology and a half-bridge sub-module topology, the inverter Transformer side converter station 200 is transformed into a flexible direct current converter station, thereby realizing a hybrid direct current transmission topology. The inverter-side converter transformer 220 of the inverter-side converter station 200 is reserved, and the wall bushing connecting the modular multi-level converter 210 and the inverter-side converter transformer 220 is reserved, and the modular multi-level converter The wall bushing connecting the converter 210 and the DC overhead line 300 is retained, and the grounding electrode is retained. Other primary equipment of AC and DC field shall be dismantled or retained according to specific implementation examples.

The hybrid DC transmission topology system shown in Figure 3 uses a double-winding converter transformer, and the DC transmission voltage level is ultra-high voltage. Each pole of the rectification-side converter station 100 is composed of a twelve-pulse bridge converter. Each twelve-pulse bridge converter is composed of two six-pulse bridge converters in series, and the two six-pulse bridge converters are connected to the AC system through a double-winding transformer on the AC side. By replacing the six-pulse bridge converter of the inverter side converter station 200 with a modular multilevel converter 210 using a full-bridge sub-module or a mixture of a full-bridge sub-module topology and a half-bridge sub-module topology, the inverter Transformer side converter station 200 is transformed into a flexible direct current converter station, thereby realizing a hybrid direct current transmission topology. The inverter-side converter transformer 220 of the inverter-side converter station 200 is reserved, and the wall bushing connecting the modular multi-level converter 210 and the inverter-side converter transformer 220 is reserved, and the modular multi-level converter The wall bushing connecting the converter 210 and the DC overhead line 300 is retained, and the grounding electrode is retained. Other primary equipment of AC and DC field shall be dismantled or retained according to specific implementation examples.

The hybrid DC transmission topology system shown in Figure 4 uses a three-winding converter transformer to connect with the AC system, and the DC transmission voltage level is UHV. Each pole of the rectification-side converter station 100 is composed of two twelve-pulse bridge converters connected in series. Each twelve-pulse bridge converter is composed of two six-pulse bridge converters in series, and the two six-pulse bridge converters are connected to the AC system through a three-winding transformer on the AC side. By replacing the six-pulse bridge converter of the inverter side converter station 200 with a modular multilevel converter 210 using a full-bridge sub-module or a mixture of a full-bridge sub-module topology and a half-bridge sub-module topology, the inverter Transformer side converter station 200 is transformed into a flexible direct current converter station, thereby realizing a hybrid direct current transmission topology. The inverter-side converter transformer 220 of the inverter-side converter station 200 is reserved, and the wall bushing connecting the modular multi-level converter 210 and the inverter-side converter transformer 220 is reserved, and the modular multi-level converter The wall bushing connecting the converter 210 and the DC overhead line 300 is retained, and the grounding electrode is retained. Other primary equipment of AC and DC field shall be dismantled or retained according to specific implementation examples.

The hybrid DC transmission topology system shown in Figure 5 uses a double-winding converter transformer, and the DC transmission voltage level is UHV. Each pole of the rectification-side converter station 100 is composed of two twelve-pulse bridge converters connected in series. Each twelve-pulse bridge converter is composed of two six-pulse bridge converters in series, and the two six-pulse bridge converters are connected to the AC system through a double-winding transformer on the AC side. By replacing the six-pulse bridge converter of the inverter side converter station 200 with a modular multilevel converter 210 using a full-bridge sub-module or a mixture of a full-bridge sub-module topology and a half-bridge sub-module topology, the inverter Transformer side converter station 200 is transformed into a flexible direct current converter station, thereby realizing a hybrid direct current transmission topology. The inverter-side converter transformer 220 of the inverter-side converter station 200 is reserved, and the wall bushing connecting the modular multi-level converter 210 and the inverter-side converter transformer 220 is reserved, and the modular multi-level converter The wall bushing connecting the converter 210 and the DC overhead line 300 is retained, and the grounding electrode is retained. Other primary equipment of AC and DC field shall be dismantled or retained according to specific implementation examples.

FIG. 6 is a schematic diagram of an inverter-side modular multilevel converter in an embodiment. Each phase of the modular multilevel converter 210 can be divided into two upper and lower bridge arms, and each bridge arm is composed of N sub-modules and bridge arm inductors connected in series with the sub-modules. The structure of the sub-modules can all adopt the full-bridge type, or partly adopt the full-bridge type and partly adopt the half-bridge type. The full-bridge sub-module structure is shown in Figure 7, which mainly includes a full-bridge circuit composed of an energy storage capacitor, four fully-controlled power semiconductors and four anti-parallel diodes. Each sub-module can output three levels of +U _c , 0, and -U _c . The half-bridge sub-module structure is shown in Figure 8, which mainly includes a half-bridge circuit composed of an energy storage capacitor, two fully-controlled power semiconductors and two anti-parallel diodes. Each sub-module can output two levels of +U _c and 0. By controlling the number of output- _Uc level sub-modules in the modular multilevel converter 210, the four-quadrant operation of the DC side and the AC side of the modular multilevel converter 210 can be realized, so that the modular multi-power The magnitude of the direct current voltage and the magnitude of the alternating current voltage output by the leveling converter 210 remain unchanged, realizing the purpose of making full use of the traditional direct current transmission primary equipment.

The above-mentioned hybrid DC power transmission topology system can be based on the traditional DC power transmission system, by replacing the inverter-side grid commutation converter with a full-bridge sub-module topology or a mix of full-bridge sub-module topology and half-bridge sub-module topology The modular multi-level converter of the company transforms the traditional DC transmission system into a flexible DC converter station, thus forming a hybrid DC topology. By retrofitting on the basis of the traditional DC transmission system, it is possible to make full use of the traditional DC transmission primary equipment at the transformed end, reduce the number of additional purchased equipment, shorten the renovation period, and reduce costs.

The various technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the various technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. A hybrid direct current transmission topology system, characterized in that it includes a rectification-side converter station and an inverter-side converter station connected to the rectification-side converter station, The rectification-side converter station includes a rectification-side converter transformer and a grid commutation converter, and the grid commutation converter is connected to the rectification-side converter transformer and the inverter-side converter station; the rectification The side converter transformer is connected to the alternating current for voltage transformation processing and then output to the grid commutation converter, and the grid commutation converter rectifies the transformed alternating current to obtain direct current and transmits it to the inverter side converter flow station; The inverter-side converter station includes a modular multilevel converter adopting a full-bridge sub-module topology, or a hybrid of a full-bridge sub-module topology and a half-bridge sub-module topology, and connecting the modular multi-level converter Converter transformer on the inverter side of the converter, the modular multilevel converter is connected to the grid commutation converter, converts the DC power delivered by the grid commutation converter to obtain AC power and transmits it to the grid commutation converter An inverter-side converter transformer is described, and the inverter-side converter transformer transforms the received AC power before outputting it. 2. The hybrid direct current transmission topology system according to claim 1, wherein the grid commutation converter is a twelve-pulse bridge converter composed of half-controlled power semiconductors, and each of the The twelve-pulse bridge converter consists of two six-pulse bridge converters connected in series. 3. The hybrid direct current transmission topology system according to claim 2, wherein the semi-controlled power semiconductor is a thyristor. 4. The hybrid DC power transmission topology system according to claim 1, wherein the full-bridge sub-module topology is composed of fully-controlled power semiconductors and energy storage capacitors that can be turned off and can output positive and negative voltages. The topological structure of flat and zero level, the topology of the half-bridge sub-module is composed of a fully-controlled power semiconductor that can be turned off and an energy storage capacitor, and can output positive level and zero level. 5. The hybrid direct current transmission topology system according to claim 4, wherein the fully controlled power semiconductor that can be turned off includes an insulated gate bipolar transistor, an integrated gate commutated thyristor, a turn-off thyristor, At least one of a power field effect transistor, an electron injection enhanced gate transistor, a gate commutated thyristor and a silicon carbide enhanced junction field effect transistor. 6 . The hybrid direct current transmission topology system according to claim 1 , wherein both the rectification-side converter transformer and the inverter-side converter transformer are double-winding transformers. 7 . The hybrid direct current transmission topology system according to claim 1 , wherein both the rectification-side converter transformer and the inverter-side converter transformer are three-winding transformers. 8. The hybrid DC power transmission topology system according to claim 1, further comprising a DC overhead line, the grid commutation converter is connected to the modular multilevel converter through the DC overhead line connect. 9. The hybrid DC power transmission topology system according to claim 8, wherein the inverter station further includes an AC wall bushing and a DC wall bushing, and the modular multilevel converter The converter is connected to the inverter side converter transformer through the AC wall bushing, and the modular multilevel converter is connected to the DC overhead line through the DC wall bushing. 10. The hybrid DC power transmission topology system according to claim 1, wherein the rectification-side converter station further includes a rectification-side grounding electrode connected to the grid commutation converter, and the inverter-side commutation The station also includes a ground electrode connected to the inverter side of the block multilevel converter.