Static synchronous phase modifier, control method and related product

Abstract

The invention discloses a static synchronous phase modifier, a control method and a related product. Each phase of the static synchronous phase modifier comprises an H-bridge circuit, a converter valve circuit and a super-capacitance valve circuit; the converter valve circuit comprises a plurality of half-bridge sub-modules which are connected in series; the first end of the alternating-current side of each H-bridge circuit is connected with a corresponding alternating-current bus, the second end of the alternating-current side of each H-bridge circuit is connected with the second ends of the alternating-current sides of the H-bridge circuits in the other two phases, the first end of the direct-current side of each H-bridge circuit is connected with the first end of the converter valve circuit, and the second end of the direct-current side of each H-bridge circuit is connected with the second end of the converter valve circuit; the super-capacitance valve circuit is connected in parallel with two ends of the converter valve circuit. In the embodiment of the invention, the half-bridge sub-module is adopted in the converter valve circuit, so that the number of power devices in the converter valve circuit is reduced, and the cost of the static synchronous phase modifier is further reduced; and the converter valve circuit and the super-capacitance valve circuit are separately arranged, so that the safety of the static synchronous phase modifier is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, in particular to a static synchronous compensator, a control method and related products. BACKGROUND

[0002] The static synchronous compensator (SSC) is a network configuration type static var generator (SVG) with super capacitor (super capacitor for short) configured on the power electronic reactive power compensation device. The SSC has strong active and reactive power support capability and can provide inertia and voltage support for the system.

[0003] The existing SSC topology structure is mainly divided into two categories: one is the SSC topology based on the modular multilevel converter (MMC) (MMC-SSC), the AC side of the MMC-SSC adopts full-bridge sub-modules, and the large number of power devices leads to high cost; the other is the SSC topology based on the cascaded H-bridge (CHB) (CHB-SSC), the CHB-SSC adopts the configuration mode of integrating super capacitor and converter valve, and once the super capacitor fails, it will directly affect the operation of the converter valve group, and the safety is low. SUMMARY

[0004] Based on the above problems, the present application provides a static synchronous compensator, a control method and related products, which reduce the cost of the static synchronous compensator and improve the safety of the static synchronous compensator.

[0005] The embodiments of the present application disclose the following technical solutions:

[0006] (The supplement will be made after the determination of the claims, see the claims)

[0007] The embodiments of the present application provide a static synchronous compensator, a control method and related products, and half-bridge sub-modules are used in the converter valve circuit to reduce the number of power devices in the converter valve circuit, thereby reducing the cost of the static synchronous compensator; in the embodiments of the present application, the converter valve circuit and the super capacitor valve circuit are separately arranged, and the failure of the super capacitor valve circuit does not affect the operation of the converter valve circuit, thereby improving the safety of the static synchronous compensator. In addition, the static synchronous compensator in the embodiments of the present application includes an H-bridge circuit, a converter valve circuit and a super capacitor valve circuit, based on the above topology structure, the super capacitor valve circuit is mainly used to provide fast active power support and fine voltage regulation, and does not need to bear the entire power support task, therefore, a large number of super capacitors do not need to be configured in the super capacitor valve circuit, thereby further reducing the cost of the static synchronous compensator. BRIEF DESCRIPTION OF DRAWINGS

[0008] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some of the embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings belong to the protection scope of the present application.

[0009] Figure 1 A schematic diagram of a static synchronous compensator is provided for the embodiments of the present application.

[0010] Figure 2 A working waveform schematic diagram of a static synchronous compensator is provided for the embodiments of the present application.

[0011] Figure 3 A schematic diagram of a half-bridge sub-module is provided for the embodiments of the present application.

[0012] Figure 4 A schematic diagram of another half-bridge sub-module is provided for the embodiments of the present application.

[0013] Figure 5 A running schematic diagram of a half-bridge sub-module is provided for the embodiments of the present application.

[0014] Figure 6 A schematic diagram of an over-capacity module is provided for the embodiments of the present application.

[0015] Figure 7 A flow chart of a control method of a static synchronous compensator is provided for the embodiments of the present application.

[0016] Figure 8 A schematic diagram of a control device is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0017] In order to make the person skilled in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0018] The terms "first" and "second" and the like in the specification and claims of the present application are used to distinguish different objects, not to describe a specific order of the objects. For example, the first single switch circuit and the second single switch circuit are used to distinguish different single switch circuits, not to describe a specific order of the single switch circuits.

[0019] In the embodiments of the present application, the word "exemplary" or "for example" is used to mean serving as an example, instance, or illustration. Any embodiment or design described in this application as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word "exemplary" or "for example" is intended to present concepts in a concrete manner.

[0020] In the description of the embodiments of the present application, unless otherwise specified, "a plurality of" means two or more, for example, a plurality of processing units means two or more processing units, and the like; a plurality of elements means two or more elements, and the like.

[0021] At present, the topologies of SSCs are mainly divided into two categories: one is a SSC topology based on a modular multilevel converter (MMC) (referred to as MMC-SSC), and the AC side of the MMC-SSC adopts full-bridge sub-modules, and the large number of power devices leads to high cost; the other is a SSC topology based on a cascaded H-bridge (CHB) (referred to as CHB-SSC), and the CHB-SSC adopts a configuration mode of super capacitor and valve integration, and once the super capacitor fails, the valve group operation will be directly affected, and the safety is low.

[0022] Therefore, the embodiments of the present application provide a SSC of a hybrid multilevel converter in parallel arrangement (PHMC) type (referred to as PHMC-SSC), which comprises an H-bridge circuit, a converter valve circuit and a super capacitor valve circuit; wherein the converter valve circuit comprises a plurality of series-connected half-bridge sub-modules; the first AC side end of the H-bridge circuit is used for connecting the corresponding AC bus, the second AC side end of the H-bridge circuit is connected together with the second AC side end of the H-bridge circuit in the other two phases, the first DC side end of the H-bridge circuit is connected to the first end of the converter valve circuit, and the second DC side end of the H-bridge circuit is connected to the second end of the converter valve circuit; the first end of the super capacitor valve circuit is connected to the first end of the converter valve circuit, and the second end of the super capacitor valve circuit is connected to the second end of the converter valve circuit.

[0023] The half-bridge sub-modules are used in the converter valve circuit to reduce the number of power devices in the converter valve circuit, and thus reduce the cost of the static synchronous compensator. In the embodiment, the converter valve circuit is separately arranged from the super-capacitor valve circuit, so that the failure of the super-capacitor valve circuit does not affect the operation of the converter valve circuit, and the safety of the static synchronous compensator is improved. In addition, the static synchronous compensator in the embodiment includes an H-bridge circuit, a converter valve circuit, and a super-capacitor valve circuit. Based on the above topology, the super-capacitor valve circuit is mainly used to provide rapid active power support and fine voltage regulation, and does not need to bear the entire power support task. Therefore, a large number of super-capacitors do not need to be configured in the super-capacitor valve circuit, and the cost of the static synchronous compensator is further reduced.

[0024] In order for those skilled in the art to well understand and implement the technical solutions provided by the embodiments of the present application, the architecture of the static synchronous compensator will be introduced below with reference to the drawings.

[0025] Referring to Figure 1 , the figure is a schematic diagram of a static synchronous compensator provided by an embodiment of the present application.

[0026] As Figure 1 shown, each phase of the static synchronous compensator includes an H-bridge circuit 100, a converter valve circuit 200, and a super-capacitor valve circuit 300.

[0027] The a-phase includes the H-bridge circuit 100, the converter valve circuit 200, and the super-capacitor valve circuit 300. The H-bridge circuit 100 includes a first switching component S A1 , a second switching component S A2 , a third switching component S A3 , and a fourth switching component S A4 . The converter valve circuit 200 includes a first half-bridge sub-module HBSM A1 , a second half-bridge sub-module HBSM A2 , and an n-th half-bridge sub-module HBSM An . The super-capacitor valve circuit includes a first super-capacitor module SCM A1 , a second super-capacitor module SCM A2 , and an m-th super-capacitor module SCM Am . The first end (the midpoint of the first switching component S A1 and the third switching component S A3 ) of the AC side of the H-bridge circuit 100 is connected to an AC bus u sa through a first inductor L1, and the first end of the DC side of the H-bridge circuit 100 (the end point of the first switching component S A1 and the second switching component S A2 ) is connected to the first end of the converter valve circuit 200. The second end (the end point of the third switching component S A3 and the fourth switching component S A4the second end of the super-capacitor valve circuit 300 is connected to the second end of the converter valve circuit 200.

[0028] For example, the number of switching devices in the first switching assembly S A1 , the second switching assembly S A2 , the third switching assembly S A3 and the fourth switching assembly S A4 is not specifically limited in the embodiments of the present application, and can be determined according to the voltage withstand level of the switching devices and the working voltage of the application scenario.

[0029] It should be understood that the number n of half-bridge sub-modules in the above-mentioned converter valve and the number m of super-capacitor modules in the super-capacitor valve are both integers greater than or equal to 1.

[0030] The b phase includes the H-bridge circuit 100, the converter valve circuit 200 and the super-capacitor valve circuit 300. The H-bridge circuit 100 includes the first switching assembly S B1 , the second switching assembly S B2 , the third switching assembly S B3 and the fourth switching assembly S B4 . The converter valve circuit 200 includes the first half-bridge sub-module HBSM B1 , the second half-bridge sub-module HBSM B2 ,..., and the n-th half-bridge sub-module HBSM Bn . The super-capacitor valve circuit includes the first super-capacitor module SCM B1 , the second super-capacitor module SCM B2 ,..., and the m-th super-capacitor module SCM Bm . The first end (the midpoint of the first switching assembly S B1 and the third switching assembly S B3 ) of the AC side of the H-bridge circuit 100 is connected to the AC bus u sb through the second inductor L2. The first end (the end point of the first switching assembly S B1 and the second switching assembly S B2 ) of the DC side of the H-bridge circuit 100 is connected to the first end of the converter valve circuit 200, and the second end (the end point of the third switching assembly S B3 and the fourth switching assembly S B4 ) of the DC side of the H-bridge circuit 100 is connected to the second end of the converter valve circuit 200. The first end of the super-capacitor valve circuit 300 is connected to the first end of the converter valve circuit 200, and the second end of the super-capacitor valve circuit 300 is connected to the second end of the converter valve circuit 200.

[0031] The c phase includes the H-bridge circuit 100, the converter valve circuit 200 and the super-capacitor valve circuit 300. The H-bridge circuit 100 includes the first switching assembly S C1Second switch assembly S C2 Third switch assembly S C3 and the fourth switch assembly S C4 The converter valve circuit 200 includes the first half-bridge submodule HBSM. C1 Second half-bridge submodule HBSM AC2 ...the nth half-bridge submodule HBSM Cn The overcapacitance valve circuit includes a first overcapacitance module (SCM). C1 Second supercapacitive module SCM C2 ...mth supercapacitive module SCM Cm The first terminal of the AC side of the H-bridge circuit 100 (the first switching assembly S) C1 and the third switch assembly S C3 (midpoint) connected to AC bus u via third inductor L3 sc The first terminal of the DC side of the H-bridge circuit 100 (the first switching assembly S) C1 Second switch assembly S C2 The endpoints of the converter valve circuit 200 are connected to the first terminal of the H-bridge circuit 100 and the second terminal of the DC side of the H-bridge circuit 100 (the third switching component S). C3 and the fourth switch assembly S C4 The first end of the converter valve circuit 200 is connected to the second end of the converter valve circuit 200; the first end of the overcapacity valve circuit 300 is connected to the first end of the converter valve circuit 200, and the second end of the overcapacity valve circuit 300 is connected to the second end of the converter valve circuit 200.

[0032] The second terminal of the AC side of the phase a H-bridge circuit (the second switching assembly S) A2 and the fourth switch assembly S A4 The midpoint of the b-phase H-bridge circuit, the second terminal on the AC side (the second switching assembly S) B2 and the fourth switch assembly S B4 The midpoint) and the second terminal of the AC side of the c-phase H-bridge circuit (the second switching assembly S) B2 and the fourth switch assembly S B4 Connect them at their midpoints.

[0033] Based on the above topology, this application provides a schematic diagram of the working waveform of a stationary synchronous condenser, as shown below. Figure 2 As shown.

[0034] The waveform of the output voltage of the converter valve circuit is as follows: Figure 2 The continuous sine wave Uc shown in (a) represents the positive half-cycle of the sinusoidal wave; the H-bridge circuit flips the nth positive half-cycle sinusoidal voltage output by the commutator valve circuit ( Figure 2 (d) The dashed part), together with the sinusoidal voltage of the (n+1)th positive half-cycle, forms the following: Figure 2 The sinusoidal voltage U shown in (d) SSC (Figure 2 (d) is the solid line portion. The control signals S for the first switching component S1 and the fourth switching component S4 of the H-bridge circuit are as follows: Figure 2 As shown in (b), the control signals S of the second switching component S2 and the third switching component S3 of the H-bridge circuit are as follows: Figure 2 As shown in (c) in the figure.

[0035] In this embodiment, a half-bridge sub-module is used in the converter valve circuit to reduce the number of power devices in the converter valve circuit, thereby reducing the cost of the static synchronous condenser. In this embodiment, the converter valve circuit and the overcapacity valve circuit are set separately, so that the operation of the converter valve circuit is not affected by the failure of the overcapacity valve circuit, improving the safety of the static synchronous condenser. In addition, the static synchronous condenser in this embodiment includes an H-bridge circuit, a converter valve circuit, and an overcapacity valve circuit. Based on the above topology, the overcapacity valve circuit is mainly used to provide fast active power support and fine voltage regulation, and does not need to undertake the entire power support task. Therefore, the overcapacity valve circuit does not need to be configured with a large amount of overcapacity, further reducing the cost of the static synchronous condenser.

[0036] To facilitate understanding of the technical solution of this application, the specific structures of the converter valve circuit and the overcapacity valve circuit will be described below.

[0037] For converter valve circuits, embodiments of this application provide a half-bridge sub-module, the schematic diagram of which is shown below. Figure 3 As shown.

[0038] like Figure 3 The half-bridge sub-module shown includes a first switching device T1, a second switching device T2, and a first capacitor C1. Both the first switching device T1 and the second switching device T2 include a freewheeling diode.

[0039] The first terminal of the first switching device T1 is connected to the first terminal of the first capacitor C1, and the second terminal of the first switching device T1 is connected to the first terminal of the second switching device T2; the second terminal of the second switching device T2 is connected to the second terminal of the first capacitor C1.

[0040] In this embodiment, by controlling the first switching device T1 to be turned on and the second switching device T2 to be turned off, the half-bridge submodule outputs a +Uc level; by controlling the second switching device T2 to be turned on and the first switching device T1 to be turned off, the half-bridge submodule outputs a 0 level, so that the output voltage of the converter valve circuit is the positive half-cycle of a sine wave.

[0041] For the converter valve circuit, this application provides another half-bridge sub-module, the schematic diagram of which is shown below. Figure 4 As shown.

[0042] like Figure 4The shown half-bridge sub-module includes a first switching device T1, a second switching device T2, a third switching device T3, a first diode D1, a first capacitor C1 and a resistor R1. The first switching device T1, the second switching device T2 and the third switching device T3 each include a freewheeling diode.

[0043] The first end of the first switching device T1 is connected to the first end of the first capacitor C1, and the second end of the first switching device T1 is connected to the first end of the second switching device T2; the second end of the second switching device T2 is connected to the second end of the first capacitor C1; the first end of the third switching device T3 is connected to the first end of the first capacitor C1, and the second end of the third switching device T3 is connected to the first end of the first diode D1; the second end of the first diode D1 is connected to the second end of the first capacitor C1; and the resistor R1 is connected in parallel across the first diode.

[0044] The half-bridge sub-module corresponding to the converter valve circuit can not only output the positive half-cycle voltage of the sine wave, but also realize bidirectional regulation of active power.

[0045] Specifically, as shown in (a) of FIG. 1, Figure 5 if the grid frequency is less than a preset threshold, the first switching device T1 is controlled to be turned on, the second switching device T2 is controlled to be turned off, and the third switching device T3 is controlled to be turned off, so that the super-capacitor valve circuit outputs active power to the grid; as shown in (b) of FIG. 1, Figure 5 if the grid frequency is greater than the preset threshold, the third switching device T3 is controlled to be turned on, the first switching device T1 is controlled to be turned off, and the second switching device T2 is controlled to be turned off, so that the super-capacitor valve circuit and the resistor R1 absorb active power from the grid.

[0046] The embodiment of the present application introduces a bleeder resistor in the half-bridge sub-module, and on the basis of realizing the basic function (outputting the positive half-cycle voltage waveform of the sine wave) of the half-bridge sub-module, bidirectional regulation of active power can be realized at a lower cost.

[0047] For the super-capacitor valve circuit, the embodiment of the present application provides a super-capacitor module, a schematic diagram of which is shown in FIG. 2. Figure 6

[0048] As shown in FIG. 2, Figure 6 the super-capacitor module includes a fourth switching device T4, a fifth switching device T5, a second capacitor C2 and a series capacitor group C ser . The fourth switching device T4 and the fifth switching device T5 each include a freewheeling diode.

[0049] The first end of the fourth switching device T4 is connected to the first end of the second capacitor C2, and the second end of the fourth switching device T4 is connected to the first end of the fifth switching device T5; the second end of the fifth switching device T5 is connected to the second end of the second capacitor C2; and the series capacitor group C ser ​a first end of the first capacitor C1 is connected to a first end of the second capacitor C2, and a second end of the first capacitor C1 is connected to a second end of the second capacitor C2. ser a second end of the first capacitor C1 is connected to a second end of the second capacitor C2.

[0050] In the embodiments of the present application, the switching of the super-capacitor module is realized by the fourth switch device and the fifth switch device. For example, when the fourth switch device T4 is turned on, the corresponding super-capacitor module is connected to the circuit; when the fifth switch device T5 is turned on, the corresponding super-capacitor module is cut off from the circuit.

[0051] Compared with the prior art, the static synchronous compensator in the embodiments of the present application can reduce the number of super-capacitor modules. For ease of understanding, the following examples are used for illustration.

[0052] Taking the static synchronous compensator with CHB-SSC topology as an example, if the single voltage of the super-capacitor valve sub-module is 1.6 kV, and the active support is provided to the system, the super-capacitor voltage decreases from 1.6 kV to 1 kV; in order to maintain the 30 kV alternating voltage, 30 modules (30 / 1=30) are required for each phase of the super-capacitor valve. In contrast, the PHMC-SSC topology proposed in the present application uses the super-capacitor modules to superimpose the distributed super-capacitor voltage to replace the direct voltage (60 kV) equivalently, and the single-phase super-capacitor valve only needs to meet the 20 kV direct voltage, so only 20 modules (20 / 1=20) are required, and the number of super-capacitor configurations is reduced by 1 / 3.

[0053] In addition, based on the PHMC-SSC proposed in the embodiments of the present application, when the switch device in the H-bridge circuit operates, the second switch device in the half-bridge sub-module is turned on to realize the bypass of the half-bridge sub-module, thereby realizing the zero-voltage turn-on and turn-off of the switch device in the H-bridge circuit and reducing the switching loss.

[0054] Based on the static synchronous compensator provided in the above embodiments, the present application further provides a control method of the static synchronous compensator, which will be described in detail below with reference to the accompanying drawings.

[0055] Each phase of the static synchronous compensator includes an H-bridge circuit, a converter valve circuit and a super-capacitor valve circuit; wherein the converter valve circuit includes a plurality of half-bridge sub-modules connected in series; the first end of the alternating side of the H-bridge circuit is used to connect the corresponding alternating bus, the second end of the alternating side of the H-bridge circuit is connected together with the second end of the alternating side of the H-bridge circuit in the other two phases, the first end of the direct side of the H-bridge circuit is connected to the first end of the converter valve circuit, the second end of the direct side of the H-bridge circuit is connected to the second end of the converter valve circuit; the first end of the super-capacitor valve circuit is connected to the first end of the converter valve circuit, and the second end of the super-capacitor valve circuit is connected to the second end of the converter valve circuit.

[0056] As shown in FIG. 1, Figure 7 the method comprises:

[0057] S100: control the converter valve circuit to make the converter valve circuit output the positive half cycle voltage of the sine wave.

[0058] S200: control the H-bridge circuit to flip the nth positive half cycle sine voltage output by the converter valve circuit to form a sine wave voltage with the n+1th positive half cycle voltage and output the sine wave voltage; wherein n is an integer greater than or equal to 1.

[0059] The half-bridge sub-module is used in the converter valve circuit to reduce the number of power devices in the converter valve circuit, thereby reducing the cost of the static synchronous compensator. In the embodiment of the present application, the converter valve circuit is separately arranged from the super-capacitor valve circuit, so that the failure of the super-capacitor valve circuit does not affect the operation of the converter valve circuit, thereby improving the safety of the static synchronous compensator. In addition, the static synchronous compensator in the embodiment of the present application includes an H-bridge circuit, a converter valve circuit and a super-capacitor valve circuit. Based on the above topology, the super-capacitor valve circuit is mainly used to provide rapid active support and fine voltage regulation, and does not need to bear the entire power support task. Therefore, a large number of super-capacitors do not need to be configured in the super-capacitor valve circuit, thereby further reducing the cost of the static synchronous compensator.

[0060] In one implementation, the half-bridge sub-module includes: a first switching device, a second switching device and a first capacitor; wherein the first switching device and the second switching device each include a freewheeling diode; a first end of the first switching device is connected to a first end of the first capacitor, and a second end of the first switching device is connected to a first end of the second switching device; and a second end of the second switching device is connected to a second end of the first capacitor.

[0061] In one implementation, the super-capacitor valve circuit includes a plurality of super-capacitor modules connected in series; wherein each super-capacitor module includes a fourth switching device, a fifth switching device, a second capacitor and a series capacitor group; a first end of the fourth switching device is connected to a first end of the second capacitor, and a second end of the fourth switching device is connected to a first end of the fifth switching device; a second end of the fifth switching device is connected to a second end of the second capacitor; a first end of the series capacitor group is connected to the first end of the second capacitor, and a second end of the series capacitor group is connected to the second end of the second capacitor.

[0062] In one implementation, the half-bridge sub-module includes: a first switching device, a second switching device, a third switching device, a first diode, a first capacitor and a resistor; wherein the first switching device, the second switching device and the third switching device each include a freewheeling diode; a first end of the first switching device is connected to a first end of the first capacitor, and a second end of the first switching device is connected to a first end of the second switching device; a second end of the second switching device is connected to a second end of the first capacitor; a first end of the third switching device is connected to the first end of the first capacitor, and a second end of the third switching device is connected to a first end of the first diode; a second end of the first diode is connected to the second end of the first capacitor; and the resistor is connected in parallel across the first diode.

[0063] The controller is further configured to control the first switch device to be turned on, the second switch device to be turned off, and the third switch device to be turned off to make the overcapacity valve circuit output power when the grid frequency is less than a preset threshold value; and control the third switch device to be turned on, the first switch device to be turned off, and the second switch device to be turned off to make the overcapacity valve circuit and the resistance to absorb power when the grid frequency is greater than the preset threshold value.

[0064] In one implementation, the controller is further configured to control the second switch device in each half-bridge sub-module to be turned on to make the switch device in the H-bridge circuit to be turned on with zero voltage or turned off with zero voltage.

[0065] In one possible implementation, referring to Figure 8 FIG. 1 is a schematic diagram of a control device provided by an embodiment of the present application.

[0066] The control device can include a memory 1011 and a processor 1012. The processor 1012 can be connected with the converter and can drive each switch device in the static synchronous compensator. As shown in Figure 8 The memory can be a random access memory (RAM), a flash memory, a read only memory (ROM), an EPROM memory, an Electronic Programmable ROM (EPROM), a register, a hard disk, a removable disk, or the like.

[0067] The memory 1011 can store computer instructions, and when the computer instructions stored in the memory 1011 are executed by the processor 1012, the processor 1012 can be used to execute the control method of the static synchronous compensator. The memory 1011 can also store data, such as the preset range, the preset threshold value, and the like information involved in the above embodiments.

[0068] In the embodiments described above, all or some of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or some of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded into and executed by a computer, all or some of the processes or functions according to the embodiments of the present application are generated. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatuses. The computer instructions can be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions can be transmitted from one website site, computer, server or data center to another website site, computer, server or data center through a wired (for example, coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (for example, infrared, wireless, microwave, etc.) manner. The computer readable storage medium can be any available medium accessible by a computer or a data storage device such as a server, data center, etc. including one or more available media sets. The available media can be a magnetic medium (for example, floppy disk, hard disk, magnetic tape), or a semiconductor medium (for example, solid state disk (SSD)), etc.

[0069] The embodiments of the present application also provide a readable storage medium for storing the method provided by the above-mentioned embodiments. For example, random access memory (RAM), flash memory, read only memory (ROM), EPROM memory, non-volatile read only memory (Electronic Programmable ROM, EPROM), register, hard disk, removable disk or any other form of storage medium in the art.

[0070] It should be noted that the embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to each other. For the method disclosed by the embodiments, since it corresponds to the product embodiments disclosed by the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the product embodiments.

[0071] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Therefore, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A static synchronous compensator, characterized by Each phase of the static synchronous compensator comprises: an H-bridge circuit, a converter valve circuit and an overcapacity valve circuit; wherein the converter valve circuit comprises a plurality of series-connected half-bridge sub-modules; The first AC side end of the H-bridge circuit is used for connecting a corresponding AC bus, the second AC side end of the H-bridge circuit is connected together with the second AC side end of the H-bridge circuit in the other two phases, the first DC side end of the H-bridge circuit is connected to the first end of the converter valve circuit, and the second DC side end of the H-bridge circuit is connected to the second end of the converter valve circuit; The first end of the overcapacity valve circuit is connected to the first end of the converter valve circuit, and the second end of the overcapacity valve circuit is connected to the second end of the converter valve circuit.

2. The static synchronous compensator of claim 1, wherein, The half-bridge sub-module comprises: a first switching device, a second switching device, a third switching device, a first diode, a first capacitor and a resistor; wherein the first switching device, the second switching device and the third switching device each comprise a freewheeling diode; The first end of the first switching device is connected to the first end of the first capacitor, and the second end of the first switching device is connected to the first end of the second switching device; The second end of the second switching device is connected to the second end of the first capacitor; The first end of the third switching device is connected to the first end of the first capacitor, and the second end of the third switching device is connected to the first end of the first diode; The second end of the first diode is connected to the second end of the first capacitor; The resistor is connected in parallel across the first diode.

3. The static synchronous compensator of claim 1, wherein, The half-bridge sub-module comprises: a first switching device, a second switching device and a first capacitor; wherein the first switching device and the second switching device each comprise a freewheeling diode; The first end of the first switching device is connected to the first end of the first capacitor, and the second end of the first switching device is connected to the first end of the second switching device; The second end of the second switching device is connected to the second end of the first capacitor.

4. The static synchronous compensator of claim 1, wherein, The overcapacity valve circuit comprises a plurality of series-connected overcapacity modules; wherein each overcapacity module comprises a fourth switching device, a fifth switching device, a second capacitor and a series capacitor group; The first end of the fourth switching device is connected to the first end of the second capacitor, and the second end of the fourth switching device is connected to the first end of the fifth switching device; The second end of the fifth switching device is connected to the second end of the second capacitor; The first end of the series capacitor group is connected to the first end of the second capacitor, and the second end of the series capacitor group is connected to the second end of the second capacitor.

5. The static synchronous compensator of claim 2, wherein, The static synchronous compensator further comprises a controller; The controller is configured to, in the case that the grid frequency is less than a preset threshold, control the first switching device to be turned on, the second switching device to be turned off and the third switching device to be turned off, so that the overcapacity valve circuit outputs power; in the case that the grid frequency is greater than the preset threshold, control the third switching device to be turned on, the first switching device to be turned off and the second switching device to be turned off, so that the overcapacity valve circuit and the resistor absorb power.

6. The static synchronous compensator of any one of claims 1-4, wherein, The static synchronous compensator further comprises a controller; The controller is configured to control the H-bridge circuit to flip the nth positive half-cycle sinusoidal voltage output by the converter valve circuit to form a sinusoidal wave voltage with the (n+1)th positive half-cycle sinusoidal voltage; wherein n is an integer greater than or equal to 1.

7. The static synchronous compensator of claim 6, wherein, The controller is further configured to control the second switching device in each half-bridge submodule to be turned on, so that the switching device in the H-bridge circuit is turned on with zero voltage or turned off with zero voltage.

8. A control method of a static synchronous compensator, characterized by, Each phase of the static synchronous compensator comprises an H-bridge circuit, a converter valve circuit and an overcapacity valve circuit; wherein the converter valve circuit comprises a plurality of half-bridge submodules connected in series; a first AC side end of the H-bridge circuit is used to connect a corresponding AC bus, a second AC side end of the H-bridge circuit is connected together with the second AC side end of the H-bridge circuit in the other two phases, a first DC side end of the H-bridge circuit is connected to a first end of the converter valve circuit, and a second DC side end of the H-bridge circuit is connected to a second end of the converter valve circuit; a first end of the overcapacity valve circuit is connected to the first end of the converter valve circuit, and a second end of the overcapacity valve circuit is connected to the second end of the converter valve circuit. The method comprises: controlling the converter valve circuit to output a positive half-cycle voltage of a sinusoidal wave; controlling the H-bridge circuit to flip the nth positive half-cycle sinusoidal voltage output by the converter valve circuit to form a sinusoidal wave voltage with the (n+1)th positive half-cycle voltage; wherein n is an integer greater than or equal to 1.

9. A control device characterized by comprising: The device comprises a processor and a memory, the memory is used to store programs, instructions or codes, and the processor is used to execute the programs, instructions or codes in the memory to complete the control method of claim 8.

10. A computer-readable storage medium, characterized in that, A computer program is stored, and the computer program is loaded by a processor to execute the control method of claim 8.

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