T-type nested neutral point clamped hybrid multilevel converter and power generation system

Abstract

The present invention relates to a T-type nested neutral point clamped hybrid multilevel converter, comprising a first / second / third / fourth / fifth / sixth high-frequency power electronic switch tube, a first / second low-frequency power electronic switch tube, and a first / second clamping capacitor; the first / second / fifth / sixth high-frequency power electronic switch tube is connected in series between the positive pole P point and the negative pole N point of a power generation device via a node P1, a node A, and a node N1, the fourth / third high-frequency power electronic switch tube is connected in series and connected to the node A, the first / second clamping capacitor is connected in series and then connected in parallel to the two ends of the second / fifth high-frequency power electronic switch tube and the midpoint is connected to the third high-frequency power electronic switch tube, and the first / second low-frequency power electronic switch tube is connected in series between the positive pole P point and the negative pole N point of the power generation device. The present invention can further improve the output waveform quality, reduce the filter inductance, improve the conversion efficiency, and reduce the number of power electronic switch devices, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of electric energy conversion, and in particular relates to a T-type nested neutral point clamped hybrid multi-level converter and a power generation system using the same. Background Art

[0002] Compared with two-level converters, multi-level converters have the advantages of small output voltage and current harmonics, small voltage change rate and high efficiency. In recent years, they have been widely studied and applied in renewable energy power generation systems.

[0003] Traditional multi-level converters have topologies such as diode clamped, flying capacitor, and cascaded H-bridge. However, as the number of converter output levels increases, the devices required for diode clamped multi-level converters and flying capacitor multi-level converters increase exponentially. The cascaded H-bridge multi-level converter requires an isolated DC power supply. In order to overcome the shortcomings of traditional multi-level converters, a variety of new multi-level converter structures have been proposed in recent years. For example, the invention patent named "Control Method of a Flying Capacitor Five-Level Inverter" and patent number ZL201410125395.8 discloses a flying capacitor five-level single-phase inverter, the inverter output level number is 5, and the performance and efficiency of the inverter are improved. For example, the invention patent named "Flying Capacitor Five-Level Photovoltaic Inverter" with patent number ZL201120262122.X discloses a flying capacitor five-level photovoltaic inverter, each phase of which is composed of 8 power electronic switching tubes and 5 clamping capacitors. Each phase arm of the inverter outputs five levels, which improves the performance and efficiency of the entire photovoltaic power generation system and improves the quality of the inverter output current waveform.

[0004] For the single-phase converter of the distributed power generation system, its output mainly includes two-level, three-level, five-level, etc. These existing multi-level converters still have room for improvement in output waveform quality, filter inductance, conversion efficiency, number of components, etc. Summary of the invention

[0005] The object of the present invention is to provide a T-type nested neutral point clamped hybrid multi-level converter which can further improve the output waveform quality, reduce the filter inductance, improve the conversion efficiency, and reduce the number of power electronic switch devices.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A T-type nested neutral point clamped hybrid multilevel converter is connected between a power generation device and a power grid, wherein the T-type nested neutral point clamped hybrid multilevel converter comprises a first high-frequency power electronic switch tube, a second high-frequency power electronic switch tube, a third high-frequency power electronic switch tube, a fourth high-frequency power electronic switch tube, a fifth high-frequency power electronic switch tube, a sixth high-frequency power electronic switch tube, a first low-frequency power electronic switch tube, a second low-frequency power electronic switch tube, a first clamping capacitor, and a second clamping capacitor;

[0008] The drain of the first high-frequency power electronic switch tube is connected to the positive electrode point P of the power generation device, the source of the first high-frequency power electronic switch tube is connected to the drain of the second high-frequency power electronic switch tube via node P1, the source of the second high-frequency power electronic switch tube is connected to the drain of the fifth high-frequency power electronic switch tube via node A, the source of the fifth high-frequency power electronic switch tube is connected to the drain of the sixth high-frequency power electronic switch tube via node N1, the source of the sixth high-frequency power electronic switch tube is connected to the negative electrode point N of the power generation device, the node A is connected to the drain of the fourth high-frequency power electronic switch tube, the source of the fourth high-frequency power electronic switch tube is connected to the source of the third high-frequency power electronic switch tube, and the The first end of the first clamping capacitor is connected to the node P1, the second end of the first clamping capacitor is connected to the drain of the third high-frequency power electronic switch tube, the first end of the second clamping capacitor is connected to the node N1, and the second end of the second clamping capacitor is connected to the drain of the third high-frequency power electronic switch tube; the drain of the first low-frequency power electronic switch tube is connected to the positive electrode point P of the power generation device, the source of the first low-frequency power electronic switch tube is connected to the drain of the second low-frequency power electronic switch tube via node n, and the source of the second low-frequency power electronic switch tube is connected to the negative electrode point N of the power generation device; the node A and the node n constitute the output end of the T-type nested neutral point clamped hybrid multi-level converter.

[0009] Preferably, the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the sixth high-frequency power electronic switch tube are all MOSFET tubes, and the first low-frequency power electronic switch tube and the second low-frequency power electronic switch tube are both IGBT tubes.

[0010] Preferably, the voltage controlled by the first clamping capacitor and the second clamping capacitor is V dc / 3, where V dc It is the DC bus voltage output by the power generation device.

[0011] The T-type nested neutral point clamped hybrid multilevel converter has twelve working states;

[0012] In the first working state, the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned on, and the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is V dc ;

[0013] In the second working state, the first high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned on, and the second high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is 2V. dc / 3;

[0014] In the third working state, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned on, and the first high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is 2V. dc / 3;

[0015] In the fourth working state, the first high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned on, and the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is V dc / 3;

[0016] In the fifth working state, the third high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned on, the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is V dc / 3;

[0017] In the sixth working state, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned on, the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is 0;

[0018] In the seventh working state, the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned on, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is 0;

[0019] In the eighth working state, the first high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned on, and the second high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is -V dc / 3;

[0020] In the ninth working state, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned on, and the first high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is -V dc / 3;

[0021] In the tenth working state, the first high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned on, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is -2V. dc / 3;

[0022] In the eleventh working state, the third high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned on, the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is -2V dc / 3;

[0023] In the twelfth working state, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned on, the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is -V dc .

[0024] The present invention also provides a power generation system, which comprises a power generation device, a level converter, a filter, and a power grid which are arranged in sequence. The level converter adopts the aforementioned T-type nested neutral point clamped hybrid multi-level converter.

[0025] Preferably, the power generation device is a renewable energy power generation device.

[0026] Preferably, the power generation device is a photovoltaic power generation device.

[0027] Preferably, the filter includes a first filter inductor, a second filter inductor and a filter capacitor, the first end of the first filter inductor is connected to the node A, the second end of the first filter inductor is connected to the node B, the first end of the second filter inductor is connected to the node n, the second end of the second filter inductor is connected to the node C, the two ends of the filter capacitor are respectively connected to the node B and the node C, and the power grid is respectively connected to the node B and the node C.

[0028] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: the present invention can further improve the output waveform quality, reduce the filter inductance, improve the conversion efficiency, and reduce the number of power electronic switching devices, and has a good application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Attached Figure 1 The schematic diagram of the structure of the power generation system including the T-type nested neutral point clamped hybrid multi-level converter of the present invention.

[0030] Attached Figure 2The diagram is a schematic diagram of the output state of the T-type nested neutral point clamped hybrid multi-level converter power generation system of the present invention in the first working state.

[0031] Attached Figure 3 The diagram is a schematic diagram of the output state of the T-type nested neutral point clamped hybrid multi-level converter power generation system in the second working state of the present invention.

[0032] Attached Figure 4 The diagram is a schematic diagram of the output state of the power generation system including the T-type nested neutral point clamping hybrid multi-level converter in the third working state of the present invention.

[0033] Attached Figure 5 The diagram is a schematic diagram of the output state of the T-type nested neutral point clamped hybrid multi-level converter power generation system in the fourth working state of the present invention.

[0034] Attached Figure 6 The diagram is a schematic diagram of the output state of the power generation system including the T-type nested neutral point clamping hybrid multi-level converter in the fifth working state of the present invention.

[0035] Attached Figure 7 The figure is a schematic diagram of the output state of the power generation system including the T-type nested neutral point clamping hybrid multi-level converter in the sixth working state of the present invention.

[0036] Attached Figure 8 The figure is a schematic diagram of the output state of the power generation system including the T-type nested neutral point clamping hybrid multi-level converter in the seventh working state of the present invention.

[0037] Attached Fig. 9 The figure is a schematic diagram of the output state of the power generation system including the T-type nested neutral point clamping hybrid multi-level converter in the eighth working state of the present invention.

[0038] Attached Fig.10 The figure is a schematic diagram of the output state of the power generation system including the T-type nested neutral point clamping hybrid multi-level converter in the ninth working state of the present invention.

[0039] Attached Fig.11 The diagram is a schematic diagram of the output state of the T-type nested neutral point clamped hybrid multi-level converter power generation system in the tenth working state of the present invention.

[0040] Attached Fig.12 The figure is a schematic diagram of the output state of the T-type nested neutral point clamped hybrid multi-level converter power generation system in the eleventh working state of the present invention.

[0041] Attached Fig.13 The diagram is a schematic diagram of the output state of the T-type nested neutral point clamped hybrid multi-level converter power generation system of the present invention in the twelfth working state. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the embodiments shown in the accompanying drawings.

[0043] Embodiment 1: As shown in the attached Figure 1 As shown, a power generation system includes a power generation device, a level converter, a filter and a power grid arranged in sequence. g Among them, the power generation device is a renewable energy power generation device, such as a photovoltaic power generation device, Figure 1 China-Israel Power Supply dc and resistor R dc Equivalent.

[0044] Connected to the power generation device and the grid g The level converter between them adopts a T-type nested neutral point clamped hybrid multilevel converter, which includes a first high-frequency power electronic switch tube S1, a second high-frequency power electronic switch tube S2, a third high-frequency power electronic switch tube S3, a fourth high-frequency power electronic switch tube S4, a fifth high-frequency power electronic switch tube S5, a sixth high-frequency power electronic switch tube S6, a first low-frequency power electronic switch tube S7, a second low-frequency power electronic switch tube S8, a first clamping capacitor C1 and a second clamping capacitor C2.

[0045] The drain of the first high-frequency power electronic switch tube S1 is connected to the positive electrode point P of the power generation device, the source of the first high-frequency power electronic switch tube S1 is connected to the drain of the second high-frequency power electronic switch tube S2 via the node P1, the source of the second high-frequency power electronic switch tube S2 is connected to the drain of the fifth high-frequency power electronic switch tube S5 via the node A, the source of the fifth high-frequency power electronic switch tube S5 is connected to the drain of the sixth high-frequency power electronic switch tube S6 via the node N1, the source of the sixth high-frequency power electronic switch tube S6 is connected to the negative electrode point N of the power generation device, the node A is connected to the drain of the fourth high-frequency power electronic switch tube S4, the source of the fourth high-frequency power electronic switch tube S4 is connected to the source of the third high-frequency power electronic switch tube S3. The first end of the first clamping capacitor C1 is connected to the node P1, the second end of the first clamping capacitor C1 is connected to the drain of the third high-frequency power electronic switch tube S3, the first end of the second clamping capacitor C2 is connected to the node N1, and the second end of the second clamping capacitor C2 is connected to the drain of the third high-frequency power electronic switch tube S3; the drain of the first low-frequency power electronic switch tube S7 is connected to the positive electrode point P of the power generation device, the source of the first low-frequency power electronic switch tube S7 is connected to the drain of the second low-frequency power electronic switch tube S8 via the node n, and the source of the second low-frequency power electronic switch tube S8 is connected to the negative electrode point N of the power generation device; the node A and the node n constitute the output end of the T-type nested neutral point clamped hybrid multi-level converter.

[0046] In the above scheme, the first high-frequency power electronic switch tube S1, the second high-frequency power electronic switch tube S2, the third high-frequency power electronic switch tube S3, the fourth high-frequency power electronic switch tube S4, the fifth high-frequency power electronic switch tube S5, and the sixth high-frequency power electronic switch tube S6 are all MOSFET tubes, and the first low-frequency power electronic switch tube S7 and the second low-frequency power electronic switch tube S8 are all IGBT tubes.

[0047] The filter includes a first filter inductor L1, a second filter inductor L2 and a filter capacitor C3. The first end of the first filter inductor L1 is connected to the node A, the second end of the first filter inductor L1 is connected to the node B, the first end of the second filter inductor L2 is connected to the node n, the second end of the second filter inductor L2 is connected to the node C, and the two ends of the filter capacitor C3 are connected to the node B and the node C respectively. The power grid e g Connected to Node B and Node C respectively.

[0048] T-type nested neutral point clamped hybrid multilevel converter can be used according to the grid e g To meet the requirements of active power and reactive power control, the LC filter can filter out the high-order harmonics in the converter and meet the requirements of the grid-connected inverter for grid-connected harmonics.

[0049] In the above-mentioned T-type nested neutral point clamped hybrid multilevel converter, the voltage controlled by the first clamping capacitor C1 and the second clamping capacitor C2 are both V dc / 3, where V dc It is the DC bus voltage output by the generator.

[0050] The T-type nested neutral point clamped hybrid multilevel converter has twelve working states. The switch states and input voltages corresponding to the T-type nested neutral point clamped hybrid multilevel converter in each state are shown in Table 1.

[0051] Table 1 Relationship between the output voltage and the converter switching state of the T-type nested neutral point clamped hybrid multilevel converter

[0052]

[0053] As attached Figure 2 As shown, in the first working state, the first high-frequency power electronic switch tube S1, the second high-frequency power electronic switch tube S2, the third high-frequency power electronic switch tube S3, and the second low-frequency power electronic switch tube S8 are turned on, and the fourth high-frequency power electronic switch tube S4, the fifth high-frequency power electronic switch tube S5, the sixth high-frequency power electronic switch tube S6, and the first low-frequency power electronic switch tube S7 are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is V dc .

[0054] As attached Figure 3 As shown, in the second working state, the first high-frequency power electronic switch tube S1, the third high-frequency power electronic switch tube S3, the fourth high-frequency power electronic switch tube S4, and the second low-frequency power electronic switch tube S8 are turned on, and the second high-frequency power electronic switch tube S2, the fifth high-frequency power electronic switch tube S5, the sixth high-frequency power electronic switch tube S6, and the first low-frequency power electronic switch tube S7 are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is 2V. dc / 3.

[0055] As attached Figure 4 As shown, in the third working state, the second high-frequency power electronic switch tube S2, the third high-frequency power electronic switch tube S3, the sixth high-frequency power electronic switch tube S6, and the second low-frequency power electronic switch tube S8 are turned on, the first high-frequency power electronic switch tube S1, the fourth high-frequency power electronic switch tube S4, the fifth high-frequency power electronic switch tube S5, and the first low-frequency power electronic switch tube S7 are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multi-level converter is 2V. dc / 3.

[0056] As attached Figure 5 As shown, in the fourth working state, the first high-frequency power electronic switch tube S1, the fourth high-frequency power electronic switch tube S4, the fifth high-frequency power electronic switch tube S5, and the second low-frequency power electronic switch tube S8 are turned on, and the second high-frequency power electronic switch tube S2, the third high-frequency power electronic switch tube S3, the sixth high-frequency power electronic switch tube S6, and the first low-frequency power electronic switch tube S7 are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is V dc / 3.

[0057] As attached Figure 6 As shown, in the fifth working state, the third high-frequency power electronic switch tube S3, the fourth high-frequency power electronic switch tube S4, the sixth high-frequency power electronic switch tube S6, and the second low-frequency power electronic switch tube S8 are turned on, the first high-frequency power electronic switch tube S1, the second high-frequency power electronic switch tube S2, the fifth high-frequency power electronic switch tube S5, and the first low-frequency power electronic switch tube S7 are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is V dc / 3.

[0058] As attached Figure 7As shown, in the sixth working state, the fourth high-frequency power electronic switch tube S4, the fifth high-frequency power electronic switch tube S5, the sixth high-frequency power electronic switch tube S6, and the second low-frequency power electronic switch tube S8 are turned on, the first high-frequency power electronic switch tube S1, the second high-frequency power electronic switch tube S2, the third high-frequency power electronic switch tube S3, and the first low-frequency power electronic switch tube S7 are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is 0.

[0059] As attached Figure 8 As shown, in the seventh working state, the first high-frequency power electronic switch tube S1, the second high-frequency power electronic switch tube S2, the third high-frequency power electronic switch tube S3, and the first low-frequency power electronic switch tube S7 are turned on, the fourth high-frequency power electronic switch tube S4, the fifth high-frequency power electronic switch tube S5, the sixth high-frequency power electronic switch tube S6, and the second low-frequency power electronic switch tube S8 are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is 0.

[0060] As attached Fig. 9 As shown, in the eighth working state, the first high-frequency power electronic switch tube S1, the third high-frequency power electronic switch tube S3, the fourth high-frequency power electronic switch tube S4, and the first low-frequency power electronic switch tube S7 are turned on, and the second high-frequency power electronic switch tube S2, the fifth high-frequency power electronic switch tube S5, the sixth high-frequency power electronic switch tube S6, and the second low-frequency power electronic switch tube S8 are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is -V dc / 3.

[0061] As attached Fig.10 As shown, in the ninth working state, the second high-frequency power electronic switch tube S2, the third high-frequency power electronic switch tube S3, the sixth high-frequency power electronic switch tube S6, and the first low-frequency power electronic switch tube S7 are turned on, the first high-frequency power electronic switch tube S1, the fourth high-frequency power electronic switch tube S4, the fifth high-frequency power electronic switch tube S5, and the second low-frequency power electronic switch tube S8 are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is -V dc / 3.

[0062] As attached Fig.11 As shown, in the tenth working state, the first high-frequency power electronic switch tube S1, the fourth high-frequency power electronic switch tube S4, the fifth high-frequency power electronic switch tube S5, and the first low-frequency power electronic switch tube S7 are turned on, the second high-frequency power electronic switch tube S2, the third high-frequency power electronic switch tube S3, the sixth high-frequency power electronic switch tube S6, and the second low-frequency power electronic switch tube S8 are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is -2V. dc / 3.

[0063] As attached Fig.12 As shown, in the eleventh working state, the third high-frequency power electronic switch tube S3, the fourth high-frequency power electronic switch tube S4, the sixth high-frequency power electronic switch tube S6, and the first low-frequency power electronic switch tube S7 are turned on, the first high-frequency power electronic switch tube S1, the second high-frequency power electronic switch tube S2, the fifth high-frequency power electronic switch tube S5, and the second low-frequency power electronic switch tube S8 are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multi-level converter is -2V dc / 3.

[0064] As attached Fig.13 As shown, in the twelfth working state, the fourth high-frequency power electronic switch tube S4, the fifth high-frequency power electronic switch tube S5, the sixth high-frequency power electronic switch tube S6, and the first low-frequency power electronic switch tube S7 are turned on, and the first high-frequency power electronic switch tube S1, the second high-frequency power electronic switch tube S2, the third high-frequency power electronic switch tube S3, and the second low-frequency power electronic switch tube S8 are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is -V dc .

[0065] The above T-type nested neutral point clamped hybrid multi-level converter device can output seven levels, and the required power electronic switch devices are 8 (6 high-frequency power electronic switch devices and 2 low-frequency power electronic switch devices), which can further improve the output waveform quality of the single-phase inverter of the distributed power generation system, reduce the filter inductance, improve the efficiency and reduce the power electronic switch devices, etc. In particular, compared with the two-level converter, the size of the converter filter inductance can be greatly reduced.

[0066] In summary, the beneficial effects of this solution are: this topology fully utilizes the characteristics of low-voltage MOSFET power electronic switch devices, such as low turn-on and turn-off losses, and only requires 6 high-frequency power electronic switches and 2 low-frequency power electronic switch devices. Compared with the traditional five-level converter, there are 2 more low-frequency power electronic switches and 2 fewer high-frequency power electronic switches. However, the number of converter output levels is increased from the traditional 5 to 7, which greatly improves the performance of the single-phase photovoltaic converter and greatly reduces the inverter filter inductance. Therefore, the photovoltaic power generation system of this topology has a good application prospect.

[0067] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A T-type nested neutral point clamped hybrid multilevel converter connected between a power generation device and a power grid, characterized in that: The T-type nested neutral point clamped hybrid multi-level converter comprises a first high-frequency power electronic switch tube, a second high-frequency power electronic switch tube, a third high-frequency power electronic switch tube, a fourth high-frequency power electronic switch tube, a fifth high-frequency power electronic switch tube, a sixth high-frequency power electronic switch tube, a first low-frequency power electronic switch tube, a second low-frequency power electronic switch tube, a first clamping capacitor and a second clamping capacitor; The drain of the first high-frequency power electronic switch tube is connected to the positive electrode point P of the power generation device, the source of the first high-frequency power electronic switch tube is connected to the drain of the second high-frequency power electronic switch tube via node P1, the source of the second high-frequency power electronic switch tube is connected to the drain of the fifth high-frequency power electronic switch tube via node A, the source of the fifth high-frequency power electronic switch tube is connected to the drain of the sixth high-frequency power electronic switch tube via node N1, the source of the sixth high-frequency power electronic switch tube is connected to the negative electrode point N of the power generation device, the node A is connected to the drain of the fourth high-frequency power electronic switch tube, the source of the fourth high-frequency power electronic switch tube is connected to the source of the third high-frequency power electronic switch tube, and the The first end of the first clamping capacitor is connected to the node P1, the second end of the first clamping capacitor is connected to the drain of the third high-frequency power electronic switch tube, the first end of the second clamping capacitor is connected to the node N1, and the second end of the second clamping capacitor is connected to the drain of the third high-frequency power electronic switch tube; the drain of the first low-frequency power electronic switch tube is connected to the positive electrode point P of the power generation device, the source of the first low-frequency power electronic switch tube is connected to the drain of the second low-frequency power electronic switch tube via node n, and the source of the second low-frequency power electronic switch tube is connected to the negative electrode point N of the power generation device; the node A and the node n constitute the output end of the T-type nested neutral point clamped hybrid multi-level converter.

2. The T-type nested neutral point clamped hybrid multilevel converter according to claim 1, characterized in that: The first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the sixth high-frequency power electronic switch tube are all MOSFET tubes, and the first low-frequency power electronic switch tube and the second low-frequency power electronic switch tube are all IGBT tubes.

3. The T-type nested neutral point clamped hybrid multilevel converter according to claim 1, characterized in that: The voltages controlled by the first clamping capacitor and the second clamping capacitor are both V dc / 3, where V dc It is the DC bus voltage output by the power generation device.

4. The T-type nested neutral point clamped hybrid multilevel converter according to claim 3, characterized in that: The T-type nested neutral point clamped hybrid multilevel converter has twelve working states; In the first working state, the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned on, and the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is V dc ; In the second working state, the first high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned on, and the second high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is 2 V dc / 3; In the third working state, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned on, and the first high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is 2 V dc / 3; In the fourth working state, the first high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned on, and the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is V dc / 3; In the fifth working state, the third high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned on, and the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is V dc / 3; In the sixth working state, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned on, the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is 0; In the seventh working state, the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned on, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is 0; In the eighth working state, the first high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned on, and the second high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is - V dc / 3; In the ninth working state, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned on, and the first high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is - V dc / 3; In the tenth working state, the first high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned on, and the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is -2 V dc / 3; In the eleventh working state, the third high-frequency power electronic switch tube, the fourth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned on, and the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is -2 V dc / 3; In the twelfth working state, the fourth high-frequency power electronic switch tube, the fifth high-frequency power electronic switch tube, the sixth high-frequency power electronic switch tube, and the first low-frequency power electronic switch tube are turned on, and the first high-frequency power electronic switch tube, the second high-frequency power electronic switch tube, the third high-frequency power electronic switch tube, and the second low-frequency power electronic switch tube are turned off, and the output voltage of the T-type nested neutral point clamped hybrid multilevel converter is - V dc .

5. A power generation system, comprising a power generation device, a level converter, a filter, and a power grid arranged in sequence, characterized in that: The level converter adopts a T-type nested neutral point clamped hybrid multi-level converter as claimed in any one of claims 1 to 4.

6. The power generation system according to claim 5, characterized in that: The power generation device is a renewable energy power generation device.

7. The power generation system according to claim 6, characterized in that: The power generation device is a photovoltaic power generation device.

8. The power generation system according to claim 5, characterized in that: The filter includes a first filter inductor, a second filter inductor and a filter capacitor, the first end of the first filter inductor is connected to the node A, the second end of the first filter inductor is connected to the node B, the first end of the second filter inductor is connected to the node n, the second end of the second filter inductor is connected to the node C, the two ends of the filter capacitor are respectively connected to the node B and the node C, and the power grid is respectively connected to the node B and the node C.

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