A double-fed wind turbine generator set stator quasi-synchronization grid-connection voltage detection system

Abstract

The application discloses a kind of double-fed wind turbine stator quasi-synchronization grid-connected voltage detection systems, the system includes the blade and hub, gear box and double-fed asynchronous generator connected in turn;The rotor loop of double-fed asynchronous generator is connected to the low voltage side of three-coil transformer by converter machine side MPR, converter DC link and converter net measurement NPR;Using the cost of other positions of double-fed wind turbine grid side, smaller space occupied, higher safety and reliability of a set of three-phase low voltage mutual inductor as virtual replacement, it can fully meet double-fed wind turbine stator high-voltage synchronization single switching grid-connected or double switching grid-connected detection grid side function.The application saves two sets of three-phase high voltage mutual inductor and the larger space occupied by it;Reduce the workload of operation and maintenance, improve the reliability of safe production operation and maintenance, and improve the economic benefit of double-fed wind turbine.

Description

Technical Field

[0001] This invention relates to the field of wind power technology, and in particular to a stator quasi-synchronous grid-connected voltage detection system for doubly fed wind turbine generators. Background Technology

[0002] In the existing doubly fed wind turbine generator set stator high voltage synchronization grid connection testing, the three-phase high voltage transformer occupies a large space, resulting in a large workload for operation and maintenance, and low reliability for safe production operation and maintenance. Summary of the Invention

[0003] The main objective of this invention is to provide a stator quasi-synchronous grid-connected voltage detection system for doubly-fed wind turbine generators, aiming to solve the technical problems of the large space occupied by three-phase high-voltage transformers, the large workload of operation and maintenance, and the low reliability of safe operation and maintenance in the current stator high-voltage synchronous grid-connected detection of doubly-fed wind turbine generators.

[0004] To achieve the above objectives, this invention provides a stator quasi-synchronous grid-connected voltage detection system for doubly-fed wind turbine generators. The system comprises blades and a hub, a gearbox, and a doubly-fed asynchronous generator connected in sequence; wherein:

[0005] The rotor circuit of the doubly-fed asynchronous generator is connected to the low-voltage side of the three-coil transformer through the converter machine-side MPR, the converter DC link, and the converter grid-side NPR; the stator circuit of the doubly-fed asynchronous generator is connected to the medium-voltage side of the three-coil transformer through the quasi-synchronous grid-connected voltage detection circuit; the high-voltage side of the three-coil transformer is connected to the power grid.

[0006] The quasi-synchronous grid-connected voltage detection circuit is connected to one end of the stator circuit through the grid-connected detection high voltage PT2. The quasi-synchronous grid-connected voltage detection circuit is connected to the high-voltage side of the three-coil transformer through a set of three-phase low voltages on the secondary side of the high-voltage side of the step-up transformer PT0 and a set of three-phase low voltages on the secondary side of the cascaded transformer PT13, or through a set of three-phase low voltages on the medium-voltage side of the transformer through a capacitive voltage sensor and the first set of three-phase low voltages on the secondary side of the cascaded transformer PT11, or through a set of three-phase low voltages on the secondary side of the transformer low-voltage side PT12.

[0007] Optionally, the three-coil transformer, the single-switching grid-connected switch K3 located on the stator circuit between the grid-connected detection high voltage PT2 and the three-coil transformer, and the transformer medium-voltage side switch K1 are integrated or not integrated into the cabinet of the enclosure unit.

[0008] Optionally, the rotor circuit of the doubly-fed asynchronous generator is connected to the medium-voltage side of the dual-coil transformer via the converter machine-side MPR, the converter DC link, and the converter grid-side NPR; the stator circuit of the doubly-fed asynchronous generator is connected to the medium-voltage side of the dual-coil transformer via a quasi-synchronous grid-connected voltage detection circuit; and the high-voltage side of the dual-coil transformer is connected to the power grid.

[0009] Optionally, the quasi-synchronous grid-connected voltage detection circuit is connected to one end of the stator circuit via the grid-connected detection high voltage PT2. The quasi-synchronous grid-connected voltage detection circuit is connected to the high-voltage side of the dual-coil transformer via a set of three-phase low voltages on the secondary side of the high-voltage PTO of the step-up transformer and a set of three-phase low voltages on the secondary side of the cascaded transformer PT13, or via a set of three-phase low voltages on the secondary side of the capacitive voltage sensor on the medium-voltage side of the transformer and a set of three-phase low voltages on the secondary side of the cascaded transformer PT11, or via a set of three-phase low voltages on the secondary side of the low-voltage side of the step-up transformer in the rotor circuit PT12.

[0010] Optionally, the dual-coil transformer, the single-switching grid-connected switch K3 and the transformer medium-voltage side switch K1, which are installed on the stator circuit between the grid-connected detection high voltage PT2 and the dual-coil transformer, are integrated or not integrated into the cabinet of the enclosure unit.

[0011] Optionally, the quasi-synchronous grid-connected voltage detection circuit is connected to one end of the stator circuit through the grid-connected detection high voltage PT2. The quasi-synchronous grid-connected voltage detection circuit is connected to the high-voltage side of the three-coil transformer through a set of three-phase low voltages on the secondary side of the high-voltage side of the step-up transformer PTO and a set of three-phase low voltages on the secondary side of the cascaded transformer PT23, or through a set of three-phase low voltages on the medium-voltage side of the transformer through a set of three-phase low voltages on the secondary side of the capacitive voltage sensor and the first set of three-phase low voltages on the secondary side of the cascaded transformer PT21, or through a set of three-phase low voltages on the secondary side of the transformer low-voltage side PT22.

[0012] Optionally, the three-coil transformer, the dual-switching grid-connected switch group JC11 / JC12 set on the stator circuit between the grid-connected detection high voltage PT2 and the three-coil transformer, and the transformer medium-voltage side switch K1 / K2 are integrated or not integrated into the cabinet of the enclosure-type unit.

[0013] Optionally, the quasi-synchronous grid-connected voltage detection circuit is connected to one end of the stator circuit via the grid-connected detection high voltage PT2. The quasi-synchronous grid-connected voltage detection circuit is connected to the high-voltage side of the dual-coil transformer via a set of three-phase low voltages on the secondary side of the high-voltage side of the step-up transformer PTO and two sets of three-phase low voltages on the secondary side of the cascaded transformer PT23. Alternatively, it can be connected to the medium-voltage side of the dual-coil transformer via a set of three-phase low voltages from the capacitive voltage sensor on the medium-voltage side of the transformer and two sets of three-phase low voltages on the secondary side of the cascaded transformer PT21. Or, it can be connected to the medium-voltage side of the dual-coil transformer via a set of three-phase low voltages on the secondary side of the low-voltage side of the step-up transformer PT22 in the rotor circuit.

[0014] Optionally, the dual-coil transformer, the dual-switching grid-connected switch JC11 / JC12 located on the stator circuit between the grid-connected detection high voltage PT2 and the dual-coil transformer, and the transformer medium-voltage side switch K1 / K2 are integrated or not integrated into the cabinet of the enclosure unit.

[0015] Optionally, the rotor circuit is further equipped with a unit auxiliary circuit switch K5, and the power grid is connected to a three-coil transformer or a two-coil transformer through a high-voltage side switch of the unit's step-up transformer.

[0016] This invention proposes a stator quasi-synchronous grid-connected voltage detection system for doubly-fed induction generator (DFIG) wind turbines. The system comprises blades and hub, a gearbox, and a DFIG asynchronous generator connected in sequence. The rotor circuit of the DFIG asynchronous generator is connected to the low-voltage side of a three-coil transformer via a converter-side MPR, a converter DC link, and a converter grid-side NPR. A set of three-phase low-voltage transformers, which are cost-effective, space-saving, and highly reliable, are used as virtual substitutes on the grid side of the DFIG wind turbine, fully meeting the grid-side function requirements for stator high-voltage synchronization detection (single-switching or double-switching). This invention saves two sets of three-phase high-voltage transformers and the space they occupy; reduces operation and maintenance workload; improves reliability during safe operation and maintenance; and simultaneously enhances the economic benefits of the DFIG wind turbine. Attached Figure Description

[0017] Figure 1 This is an electrical diagram for a conventional doubly fed wind turbine generator set with single-switching grid connection, whether it is a three-coil integrated or non-integrated box-type substation.

[0018] Figure 2 Electrical diagram for dual-coil integrated or non-integrated box-type substation dual conventional feeder wind turbine generator set with single switching grid connection.

[0019] Figure 3 This is an electrical diagram for dual-switching grid connection of conventional doubly-fed wind turbine generator sets in integrated or non-integrated three-coil transformer substations.

[0020] Figure 4This is an electrical diagram for dual-switching grid connection of conventional doubly fed wind turbine generator sets, whether integrated or non-integrated with dual coils in a transformer substation.

[0021] Figure 5 This is the electrical diagram for a single-switching grid-connected doubly-fed wind turbine generator set with a three-coil non-integrated box-type transformer.

[0022] Figure 6 This is the electrical diagram for a single-switching grid-connected doubly-fed wind turbine generator set with a three-coil integrated transformer substation.

[0023] Figure 7 This is the electrical diagram for a single-switching grid-connected doubly fed wind turbine generator set with dual coils and non-integrated box-type transformer.

[0024] Figure 8 Electrical diagram for a single-switching grid-connected doubly fed wind turbine generator set with dual coil integrated box-type transformer.

[0025] Figure 9 This is the electrical diagram for a doubly fed wind turbine generator set with dual switching and grid connection, which is a non-integrated box-type transformer with three coils.

[0026] Figure 10 Electrical diagram for dual-switching grid connection of a three-coil integrated box-type substation doubly fed wind turbine generator set.

[0027] Figure 11 This is an electrical diagram for a dual-coil non-compact integrated box-type substation doubly fed wind turbine generator set with dual switching and grid connection.

[0028] Figure 12 Electrical diagram for dual-coil compact integrated box-type substation doubly fed wind turbine generator set with dual-switching grid connection.

[0029] Explanation of icon numbers:

[0030] 1-Blade and hub; 2-Gearbox; 3-Doubly-fed asynchronous generator; 4-Converter machine-side MPR; 5-Converter DC link; 6-Converter grid-side NPR; 7-Converter grid-side contactor C1; 8-Converter grid-side switch KR1; 9-Unit auxiliary circuit switch K5; 10-Grid-connected detection high voltage PT2; 11-Double-switching quasi-synchronous grid-connected voltage detection; 12-Single-switching quasi-synchronous grid-connected voltage detection; 13-Step-up transformer high-voltage side switch K0; 14-Double-coil step-up transformer (double-switching); 15-Double-coil step-up transformer (single-switching); 16-Three-coil step-up transformer (double-switching); 17-Three-coil 18-Step-up transformer (single switching); 19-Switch K3; 20-Rotor circuit converter grid-side switch K4; 21-Transformer medium-voltage side switch K1; 22-Transformer medium-voltage side switch K2; 23-Double switching grid-connected switch group JC11 / JC12; 24-Single switching grid-connected switch K3; 25-Grid-connected detection high voltage PT1; 26-Grid-connected detection high voltage PT3; 27-Step-up transformer grid-connected high voltage PT0; 28-Capacitive voltage sensor; 29-PT11; 30-PT12; 31-PT13; 32-PT21; 33-PT22; 34-PT23.

[0031] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0032] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0033] The technical solutions of the embodiments of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the invention, and not all of them. Based on the embodiments of the invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0034] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of the invention are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0035] Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, the person should consider that such combination of technical solutions does not exist and is not within the scope of protection claimed by the invention.

[0036] like Figure 1 As shown, a virtual substitution method for grid-side detection of stator high-voltage synchronization of a doubly fed wind turbine generator set is adopted. The electrical diagram of conventional doubly fed wind turbine generator set single-switching grid connection is used, which is based on a three-coil integrated or non-integrated box transformer. The doubly fed wind turbine generator set absorbs wind energy from the blades and hub (1), and the mechanical power passes through the gearbox (2) on the mechanical transmission chain to the doubly fed asynchronous generator (3). Among them, the power of the rotor circuit passes through the converter machine-side MPR (4), the converter DC link (5) and the converter grid-side NPR (6), and then to the converter grid-side contactor C1 (7) and the converter grid-side switch KR1 (8), while the auxiliary circuit switch K5 (9) of the generator set is bypassed. The power of the sub-circuit is connected to the grid via switch K6 (19) and then to the low-voltage side of the three-coil step-up transformer (single switch) (17); the stator output power of the unit is connected to the grid-connected high voltage detection PT2 (10) and the single switch grid-connected switch K3 (24) respectively. At the stator circuit A1, the grid-connected high voltage detection PT3 (26) and the medium-voltage side switch K1 (21) of the transformer are connected respectively, and then connected to the medium-voltage side of the three-coil step-up transformer (single switch) (17). Finally, it is connected to the high-voltage side switch K0 (13) of the unit step-up transformer through the high-voltage side of the three-coil step-up transformer (single switch) (17) and connected to the grid. In addition, the secondary side of the grid-connected detection high voltage PT2 (10) and the grid-connected detection high voltage PT3 (26) are respectively connected to JK2 and JK3 on the single-switching quasi-synchronous grid-connected voltage detector (12). At the same time, the three channels D001 / BL1, D002 / BL2, and D003 / BL3 in JK2 inside the single-switching quasi-synchronous grid-connected voltage detector (12) are connected to modules TY_ANALOG_IF_2 / 3 and TY_ANALOG_IF_24 through switch E2. In JK3, the three circuits D001 / CL1, D002 / CL2, and D003 / CL3 are connected to modules TY_ANALOG_IF_2 / 5 and TY_ANALOG_IF_2 / 6 via switch E3. After the module data is converted into digital data, the secondary side three-phase low voltage amplitude, phase sequence, and phase of the grid-connected ends are compared on the background software platform. If the comparison value meets the synchronization threshold requirement, the single-switching grid-connected switch K3(24) is allowed to connect to the grid, and the doubly fed wind turbine unit starts grid-connected power generation operation.

[0037] like Figure 2As shown, a virtual substitution method for grid-side detection of stator high-voltage synchronization of a doubly fed wind turbine generator set is adopted. The method uses a conventional doubly fed wind turbine generator set single-switching grid-connection electrical diagram with dual coil integrated or non-integrated box transformer. The doubly fed wind turbine generator set absorbs wind energy from the blades and hub (1), which is transmitted to the doubly fed asynchronous generator (3) through the gearbox (2) on the mechanical transmission chain. The power of the rotor circuit is transmitted through the converter machine-side MPR (4), the converter DC link (5), and the converter grid-side NPR (6), and then to the converter grid-side contactor C1 (7) and the converter grid-side switch KR1 (8). At the same time, the bypass unit auxiliary circuit switch K5 (9) is used, and the rotor circuit is transmitted through its converter grid-side switch. K4(20) and the rotor circuit step-up transformer(18) are connected to the stator circuit A1 point via switch K6(19) to the grid. The stator output power of the unit is connected to the stator circuit A2 point, and the grid-connected detection high voltage PT2(10) and the single-switching grid-connected switch K3(24) are connected respectively. At the stator circuit A1 point, the grid-connected detection high voltage PT3(26) and the transformer medium-voltage side switch K1(21) are connected respectively. Then, it is connected to the medium-voltage side A0 point of the double-coil step-up transformer (single-switching) (15). Finally, it is connected to the high-voltage side switch K0(13) of the step-up transformer via the high-voltage side of the double-coil step-up transformer (single-switching) (15) and connected to the grid. In addition, the secondary sides of the grid-connected detection high voltage PT2 (10) and the secondary sides of the grid-connected detection high voltage PT3 (26) are respectively connected to JK2 and JK3 on the single-switching quasi-synchronous grid-connected voltage detector (13). At the same time, the three channels D001 / BL1, D002 / BL2, and D003 / BL3 in JK2 inside the single-switching quasi-synchronous grid-connected voltage detector (12) are connected to the modules TY_ANALOG_IF_2 / 3 and TY_ANALOG_IF_2 / through switch E2. 4. The three circuits D001 / CL1, D002 / CL2, and D003 / CL3 in JK3 are connected to modules TY_ANALOG_IF_2 / 5 and TY_ANALOG_IF_2 / 6 through switch E3. After the module data is converted into digital, the amplitude, phase sequence, and phase of the three-phase low voltage on the secondary side of both ends of the grid are compared on the background software platform. If the comparison value meets the synchronous threshold requirement, the single-switching grid-connected switch K3(24) is allowed to connect to the grid, and the doubly fed wind turbine starts to generate electricity on the grid.

[0038] like Figure 3As shown, a virtual substitution method for grid-side detection of stator high-voltage synchronization of a doubly fed wind turbine generator set is adopted. The electrical diagram of conventional doubly fed wind turbine generator set with dual switching grid connection is adopted using a three-coil integrated or non-integrated box transformer. The doubly fed wind turbine generator set absorbs wind energy from the blades and hub (1), which is transmitted to the doubly fed asynchronous generator (3) through the gearbox (2) on the mechanical transmission chain. The power of the rotor circuit is transmitted through the converter machine-side MPR (4), the converter DC link (5) and the converter grid-side NPR (6), and then to the converter grid-side contactor C1 (7) and the converter grid-side switch KR1 (8). At the same time, the bypass unit auxiliary circuit switch K5(9) is connected to the rotor via switch K3(19), and then connected to the low-voltage side of the three-coil step-up transformer (double switching) (16); the unit stator output power is connected to the stator circuit A2 point, and then connected to the grid-connected detection high voltage PT2(10) and the double switching grid-connected switch group JC11 / JC12(23) respectively. At the stator circuit A1 point, the grid-connected detection high voltage PT3(26) and the transformer medium-voltage side switch K1(21) are connected respectively, and then connected to the medium-voltage side output line of the three-coil step-up transformer (single switching) (17). ③ Above, at point B2 in the stator circuit, connect the grid-connected high-voltage detection PT1 (25) and the transformer medium-voltage side switch K2 (22) respectively, and then connect them to the medium-voltage side coil tap line of the three-coil step-up transformer (single switch) (17). ④Finally, the high-voltage side of the three-coil step-up transformer (double switching) (16) is connected to the high-voltage side switch K0 (13) of the unit's step-up transformer and connected to the power grid. In addition, the secondary sides of the grid-connected detection high voltage PT1 (25), the grid-connected detection high voltage PT2 (10), and the grid-connected detection high voltage PT3 (26) are respectively connected to JK1, JK2, and JK3 on the single-switching quasi-synchronous grid-connected voltage detector (11). At the same time, the three D001 / AL1, D002 / AL2, and D003 / AL3 in JK1 inside the single-switching quasi-synchronous grid-connected voltage detector (11) are connected to modules TY_ANALOG_IF_2 / 1 and TY_ANALOG_IF_2 / 2 through switch E1, while the three D001 / BL1, D002 / BL2, and D003 / BL3 in JK2 are connected to modules TY_ANALOG_IF_2 / 3 and TY_ANALOG_IF_2 / 4 through switch E2, and the three D001 / CL1, D002 / CL2, and D003 / CL3 in JK3 are connected to modules TY_ANALOG_IF_2 / 3 through switch E3. When connected to modules TY_ANALOG_IF_2 / 5 and TY_ANALOG_IF_2 / 6, the module data is converted into digital data. In mode one, the amplitude, phase sequence, and phase of the three-phase low voltage on the secondary side of the grid connection ends at points B1 and A2 are compared on the background software platform. If the comparison value meets the synchronization threshold requirement, the JC12 of the double-switching grid connection switch group JC11 / JC12(23) with the interlock JC11 disconnected is allowed to connect to the grid, and the doubly fed wind turbine starts to connect to the grid and generate electricity in mode one (the stator uses a lower voltage). In mode two, the amplitude, phase sequence, and phase of the three-phase low voltage on the secondary side of the grid connection ends at points A1 and A2 are compared on the background software platform. If the comparison value meets the synchronization threshold requirement, the JC11 of the double-switching grid connection switch group JC11 / JC12(23) with the interlock JC12 disconnected is allowed to connect to the grid, and the doubly fed wind turbine starts to connect to the grid and generate electricity in mode two (the stator uses a higher voltage).

[0039] like Figure 4As shown, a virtual substitution method for the grid side of the stator high voltage synchronous grid connection detection of a doubly fed wind turbine generator set is adopted. The electrical diagram of the conventional doubly fed wind turbine generator set with dual switching is adopted. The doubly fed wind turbine generator set absorbs wind energy from the blades and hub (1), and passes through the gearbox (2) on the mechanical transmission chain to the doubly fed asynchronous generator (3). The power of the rotor circuit passes through the converter machine side MPR (4), the converter DC link (5) and the converter grid side NPR (6), and then to the converter grid side contactor C1 (7) and the converter grid side switch KR1 (8). At the same time, the bypass unit auxiliary circuit switch K5 (9) is used. The rotor circuit is connected to the stator circuit B2 point through its converter grid side switch K4 (20) and rotor circuit step-up transformer (18) and through switch K6 (19). At point A1 in the stator circuit, connect the grid-connected high-voltage detection PT3 (26) and the transformer medium-voltage side switch K1 (21) respectively, and then connect them to the medium-voltage side outgoing line of the dual-coil step-up transformer (dual switching) (14). ③ Above, at point B2 in the stator circuit, connect the grid-connected high-voltage detection PT1 (25) and the transformer medium-voltage side switch K2 (22) respectively, and then connect them to the medium-voltage side coil tap line of the dual-coil step-up transformer (dual switching) (14). ④Finally, the high-voltage side of the boost transformer is connected to the high-voltage side switch K0 (13) of the unit via the double-coil boost transformer (double switching) (14), and then connected to the power grid. In addition, the secondary side of the grid-connected detection high voltage PT1 (25), the grid-connected detection high voltage PT2 (10), and the grid-connected detection high voltage PT3 (26) are respectively connected to JK1, JK2, and JK3 on the dual-switching quasi-synchronous grid-connected voltage detection (11). At the same time, the three D001 / AL1, D002 / AL2, and D003 / AL3 in JK1 inside the dual-switching quasi-synchronous grid-connected voltage detection (11) are connected to modules TY_ANALOG_IF_2 / 1 and TY_ANALOG_IF_2 / 2 through switch E1, while the three D001 / BL1, D002 / BL2, and D003 / BL3 in JK2 are connected to modules TY_ANALOG_IF_2 / 3 and TY_ANALOG_IF_2 / 4 through switch E2, and the three D001 / CL1, D002 / CL2, and D003 / CL3 in JK3 are connected to module through switch E3. On TY_ANALOG_IF_2 / 5 and TY_ANALOG_IF_2 / 6, the module data is converted into digital; in mode one, the amplitude, phase sequence and phase of the three-phase low voltage on the secondary side of the grid connection ends of points B1 and A2 are compared on the background software platform. If the comparison value meets the synchronization threshold requirement, the JC12 of the double-switching grid connection switch group JC11 / JC12(23) with the interlock JC11 disconnected is allowed to connect to the grid, and the doubly fed wind turbine starts to connect to the grid and generate electricity in mode one (the stator uses a lower voltage); in mode two, the amplitude, phase sequence and phase of the three-phase low voltage on the secondary side of the grid connection ends of points A1 and A2 are compared on the background software platform. If the comparison value meets the synchronization threshold requirement, the JC11 of the double-switching grid connection switch group JC11 / JC12(23) with the interlock JC12 disconnected is allowed to connect to the grid, and the doubly fed wind turbine starts to connect to the grid and generate electricity in mode two (the stator uses a higher voltage).

[0040] In this embodiment, the number of three-phase high-voltage transformers required for grid-side stator high-voltage synchronization and grid-connection detection in conventional doubly-fed induction generator (DFIG) wind turbines can be reduced. A virtual replacement set of three-phase low-voltage transformers located at other locations on the grid side of the DFIG wind turbine is used in the following implementation example:

[0041] Case 1, such as Figure 5 As shown, the stator high-voltage synchronizing single-switching grid-connected switch K3(24) and the transformer medium-voltage side switch K1(21) of the doubly fed wind turbine generator set are not integrated into the cabinet of the three-coil step-up transformer (single-switching) (17) of the box-type unit; Figure 6 As shown, the stator high-voltage synchronizing single-switching grid-connected switch K3(24) of the doubly fed wind turbine generator set is integrated into the cabinet of the three-coil step-up transformer (single-switching) (17) of the box-type unit. Figure 5 He Ru Figure 6 On the grid side, a set of three-phase low voltages on the secondary side of the high-voltage PTO (27) of its step-up transformer and a set of three-phase low voltages on the secondary side of its cascaded PT13 (31), or a set of three-phase low voltages on the secondary side of the capacitive voltage inductor (28) of the insulating support base on the medium-voltage side of its transformer and a set of three-phase low voltages on the secondary side of its cascaded PT11 (29), or a set of three-phase low voltages on the secondary side of the PT12 (30) of its transformer, can be virtually replaced respectively. Figure 1 After the high voltage PT3 (26) of the stator high voltage synchronization single-switching grid-connected detection on the grid side of the doubly fed wind turbine generator set and a set of three-phase low voltages on its secondary side, the set of three-phase low voltages on the secondary side of both the grid side and the generator side are connected to JK3 and JK2 on the single-switching quasi-synchronous grid-connected voltage detection (12), respectively. At the same time, the three paths D001 / CL1, D002 / CL2, and D003 / CL3 in JK3 inside the single-switching quasi-synchronous grid-connected voltage detection (12) are connected to the module TY_ANALOG_IF_2 / 5 and T through switch E3. On Y_ANALOG_IF_2 / 6, while the three paths D001 / BL1, D002 / BL2, and D003 / BL3 in JK2 are connected to modules TY_ANALOG_IF_2 / 3 and TY_ANALOG_IF_2 / 4 through switch E2. After the module data is converted into digital, the secondary side three-phase low voltage amplitude, phase sequence, and phase are compared on the background software platform. If the comparison value meets the synchronous threshold requirement, the single-switching grid-connected switch K3(24) is allowed to connect to the grid, and the doubly fed wind turbine starts grid-connected power generation operation.

[0042] Case 2, such as Figure 7 As shown, the stator high-voltage synchronizing single-switching grid-connected switch K3(24) and the transformer medium-voltage side switch K1(21) of the doubly fed wind turbine generator set are not integrated into the cabinet of the double-coil step-up transformer (single-switching) (15) of the box-type unit; and as shown in the figure Figure 8 As shown, the stator high-voltage synchronizing single-switching grid-connected switch K3(24) of the doubly fed wind turbine generator set is not integrated into the cabinet of the dual-coil step-up transformer (single-switching) (15) of the box-type unit. Figure 7 He Ru Figure 8 On the grid side, a set of three-phase low voltages on the secondary side of the high-voltage PTO (27) of its step-up transformer and a set of three-phase low voltages on the secondary side of its cascaded PT13 (31), or a set of three-phase low voltages on the secondary side of the capacitive voltage inductor (28) of the insulating support on the medium-voltage side of its transformer and a set of three-phase low voltages on the secondary side of its cascaded PT11 (29), or a set of three-phase low voltages on the secondary side of the low-voltage side of the rotor circuit step-up transformer (18) can be virtually replaced, such as Figure 2After the grid-connected high voltage PT3 (26) of the doubly fed wind turbine generator set stator high voltage synchronizing single-switching grid-connected detection on the grid side and a set of three-phase low voltages on its secondary side are connected to JK3 and JK2 on the single-switching quasi-synchronizing grid-connected voltage detection (12), the three-phase low voltages on the secondary side of the grid-connected detection grid side and the generator side are respectively connected to JK3 and JK2 on the single-switching quasi-synchronizing grid-connected voltage detection (12). At the same time, the three paths D001 / CL1, D002 / CL2, and D003 / CL3 in JK3 inside the single-switching quasi-synchronizing grid-connected voltage detection (12) are connected to the module TY_ANALOG_IF_2 / through switch E3. On 5 and TY_ANALOG_IF_2 / 6, while the three paths D001 / BL1, D002 / BL2, and D003 / BL3 in JK2 are connected to modules TY_ANALOG_IF_2 / 3 and TY_ANALOG_IF_2 / 4 through switch E2. After the module data is converted into digital, the amplitude, phase sequence, and phase of the three-phase low voltage on the secondary side of the grid side and the generation side are compared on the background software platform. If the comparison value meets the synchronous threshold requirement, the single-switching grid-connected switch K3(24) is allowed to connect to the grid, and the doubly fed wind turbine starts to connect to the grid and generate electricity.

[0043] Case 3, such as Figure 9 As shown, the stator high-voltage synchronous double-switching grid-connected switch group JC11 / JC12(23) of the doubly fed wind turbine generator set and the medium-voltage side switch K1(21) and the medium-voltage side switch K2(22) of the transformer are not integrated into the complete cabinet of the three-coil step-up transformer (double-switching) (16) of the box-type unit; and as shown in the figure Figure 10 As shown, the stator high-voltage synchronous double-switching grid-connected switch group JC11 / JC12(23) of the doubly fed wind turbine generator set is integrated into the cabinet of the three-coil step-up transformer (double-switching) (16) of the box-type unit. Figure 9 He Ru Figure 10 On the grid side, a set of three-phase low voltages on the secondary side of the high-voltage PTO (27) on the high-voltage side of its step-up transformer and two sets of three-phase low voltages on the secondary side of its cascaded PT23 (34), or a set of three-phase low voltages on the secondary side of the capacitive voltage inductor (28) on the insulating support of its medium-voltage side transformer and two sets of three-phase low voltages on the secondary side of its cascaded PT21 (32), or two sets of three-phase low voltages on the secondary side of its low-voltage side PT22 (33), can be virtually replaced respectively. Figure 3 The high voltage synchronous double-switching grid-connected detection high voltage PT1(25) and a set of three-phase low voltages on its secondary side and the grid-connected detection high voltage PT3(26) and a set of three-phase low voltages on its secondary side are detected. At the same time, the phase sequence and phase of each corresponding set of three-phase low voltages on the secondary side are consistent before and after the virtual substitution. Moreover, the amplitude ratio of the two sets of three-phase low voltages on the secondary side after the virtual substitution and the output line on the voltage side of the three-coil step-up transformer (double switching) (16) are also consistent. ③and coil tap wire ④ The voltage amplitude ratio remains consistent.

[0044] In addition, such as Figure 9 He Ru Figure 10 The three-phase low voltage on the secondary side of the grid-connected high voltage PT1 (25), the three-phase low voltage on the secondary side of the grid-connected high voltage PT2 (10) which is virtually replaced, and the three-phase low voltage on the secondary side of the grid-connected high voltage PT3 (26) which is virtually replaced are respectively connected to JK1, JK2, and JK3 on the single-switching quasi-synchronous grid-connected voltage detector (11). At the same time, the three channels D001 / AL1 and D002 / AL2 in JK1 inside the single-switching quasi-synchronous grid-connected voltage detector (11) are connected to JK1, JK2, and JK3 respectively. D003 / AL3 is connected to modules TY_ANALOG_IF_2 / 1 and TY_ANALOG_IF_2 / 2 via switch E1, while the three channels D001 / BL1, D002 / BL2, and D003 / BL3 in JK2 are connected to modules TY_ANALOG_IF_2 / 3 and TY_ANALOG_IF_2 / 4 via switch E2, and the three channels D001 / CL1, D002 / CL2, and D003 / CL3 in JK3 are connected to... The switch E3 is connected to modules TY_ANALOG_IF_2 / 5 and TY_ANALOG_IF_2 / 6, and the module data is converted into digital; in mode one, the three-phase low voltage amplitude, phase sequence and phase of the secondary side of the virtual replacement points B1 and A2 are compared on the background software platform. If the comparison value meets the synchronization threshold requirement, the grid connection of JC12 under the interlocking JC11 in the double switching grid connection switch group JC11 / JC12(23) is allowed to be disconnected, and the doubly fed wind turbine is connected to the grid. The grid-connected power generation starts in operation mode one (the stator operates at a lower voltage); in operation mode two, the secondary side three-phase low voltage amplitude, phase sequence and phase of the virtual replacement points A1 and A2 are compared on the background software platform. If the comparison value meets the synchronous threshold requirement, the JC11 in the double-switching grid-connected switch group JC11 / JC12(23) is allowed to be connected to the grid with the interlock JC12 disconnected. The doubly fed wind turbine starts grid-connected power generation in operation mode two (the stator operates at a higher voltage).

[0045] Case 4, such as Figure 11 As shown, the stator high-voltage synchronous double-switching grid-connected switch group JC11 / JC12(23) of the doubly fed wind turbine generator set and the medium-voltage side switch K1(21) and medium-voltage side switch K2(22) of the transformer are not integrated into the complete cabinet of the double-coil step-up transformer (double-switching) (14) of the box-type unit; and as shown in the figure Figure 12 As shown, the stator high-voltage synchronous double-switching grid-connected switch group JC11 / JC12(23) of the doubly fed wind turbine generator set is integrated into the cabinet of the double-coil step-up transformer (double-switching) (14) of the box-type unit. Figure 11 He Ru Figure 12 On the grid side, a set of three-phase low voltages on the secondary side of the high-voltage PTO (27) on the high-voltage side of its step-up transformer and two sets of three-phase low voltages on the secondary side of its cascaded PT23 (34), or a set of three-phase low voltages on the secondary side of the capacitive voltage inductor (28) on the insulating support of its transformer medium-voltage side and two sets of three-phase low voltages on the secondary side of its cascaded PT21 (32), or two sets of three-phase low voltages on the secondary side of the PT22 (33) on the low-voltage side of its rotor circuit step-up transformer (18) can be virtually replaced, such as Figure 4 The high voltage synchronous double-switching grid-connected detection high voltage PT1(25) and a set of three-phase low voltages on its secondary side and the high voltage detection high voltage PT3(26) on its secondary side are both present in the doubly fed wind turbine generator set. At the same time, the phase sequence and phase of each corresponding set of three-phase low voltages on the secondary side are consistent before and after the virtual substitution. Moreover, the amplitude ratio of the two sets of three-phase low voltages on the secondary side after the virtual substitution and the output line on the voltage side of the double-coil step-up transformer (double-switching) (14) are also present. ③ and coil tap wire ④ The voltage amplitude ratio remains consistent.

[0046] In addition, such as Figure 11 He Ru Figure 12The secondary side of the grid-connected high voltage PT1 (25), the secondary side of the virtual-replaced grid-connected high voltage PT2 (10), and the secondary side of the virtual-replaced grid-connected high voltage PT3 (26) are respectively connected to JK1, JK2, and JK3 on the double-switching quasi-synchronous grid-connected voltage detector (11). At the same time, the three-channel D001 / AL1, D002 / AL2, and D00 in JK1 inside the double-switching quasi-synchronous grid-connected voltage detector (11) are respectively connected to JK1. 3 / AL3 is connected to modules TY_ANALOG_IF_2 / 1 and TY_ANALOG_IF_2 / 2 via switch E1, while the three channels D001 / BL1, D002 / BL2, and D003 / BL3 in JK2 are connected to modules TY_ANALOG_IF_2 / 3 and TY_ANALOG_IF_2 / 4 via switch E2, and the three channels D001 / CL1, D002 / CL2, and D003 / CL3 in JK3 are connected to modules TY_ANALOG_IF_2 / 3 and TY_ANALOG_IF_2 / 4 via switch E2. Connect E3 to modules TY_ANALOG_IF_2 / 5 and TY_ANALOG_IF_2 / 6, and the module data is converted to digital; in mode one, the three-phase low voltage amplitude, phase sequence, and phase of the secondary side of the virtual replacement points B1 and A2 are compared on the background software platform. If the comparison value meets the synchronization threshold requirement, the JC12 of the double-switching grid-connected switch group JC11 / JC12(23) is allowed to be connected to the grid with the interlocking JC11 disconnected, and the doubly fed wind turbine starts. The grid-connected power generation operates in operation mode one (the stator operates at a lower voltage); in operation mode two, the amplitude, phase sequence, and phase of the three-phase low voltage on the secondary side of the virtual replacement points A1 and A2 are compared on the background software platform. If the comparison value meets the synchronous threshold requirement, the JC11 of the double-switching grid-connected switch group JC11 / JC12 (23) is allowed to be connected to the grid under the condition that the interlocking JC12 is disconnected. The doubly fed wind turbine starts grid-connected power generation in operation mode two (the stator operates at a higher voltage).

[0047] It should be noted that in the above-described virtual substitution method for the grid side of the stator high-voltage synchronization grid connection detection of a doubly-fed wind turbine generator set, the stator high-voltage synchronization grid connection switch of the doubly-fed wind turbine generator set is integrated or not integrated into the complete cabinet of the three-coil step-up transformer of the box-type unit. The low-voltage side voltage value of the transformer is less than 1KV (or 1.14KV / 1.5KV), the medium-voltage side voltage value is less than or equal to 3kV-35kV, and the high-voltage side voltage value is less than or equal to 20kV-330kV.

[0048] It should be noted that in the above-described virtual substitution method for the grid side of the stator high-voltage synchronization grid connection detection of a doubly fed wind turbine generator set, the stator high-voltage synchronization grid connection switch of the doubly fed wind turbine generator set is integrated or not integrated into the complete cabinet of the step-up second coil transformer of the box-type unit. The voltage value of the medium-voltage side of the transformer is less than or equal to 3kV-35kV, and the voltage value of the high-voltage side of the transformer is less than or equal to 20kV-330kV.

[0049] In this embodiment, the above-described virtual substitution method for grid-side stator high-voltage synchronization detection of doubly-fed induction generator (DFIG) wind turbines utilizes a set of three-phase low-voltage transformers located at other positions on the grid side of the DFIG wind turbine as virtual substitutes. This method is cost-effective, space-saving, and highly reliable, and can fully meet the grid-side stator high-voltage synchronization detection function of DFIG wind turbines, allowing for single-switching or double-switching grid connection. For single-switching grid connection detection of DFIG wind turbine stator high-voltage synchronization, it saves one set of three-phase high-voltage transformers and their significant space. For double-switching grid connection detection of DFIG wind turbine stator high-voltage synchronization, it saves two sets of three-phase high-voltage transformers and their even larger space. This reduces the workload of operation and maintenance, improves the reliability of safe operation and maintenance, and enhances the economic benefits of DFIG wind turbines.

[0050] The above are merely preferred embodiments of the invention and do not limit the patent scope of the invention. Any equivalent structural or procedural changes made using the contents of the invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the invention.

Claims

1. A stator quasi-synchronous grid-connected voltage detection system for a doubly-fed wind turbine generator, characterized in that, The system comprises blades and hub, a gearbox, and a doubly-fed asynchronous generator connected in sequence; wherein: The rotor circuit of the doubly-fed asynchronous generator is connected to the low-voltage side of the three-coil transformer via the converter machine-side MPR, the converter DC link, and the converter grid-side NPR; the stator circuit of the doubly-fed asynchronous generator is connected to the medium-voltage side of the three-coil transformer via the quasi-synchronous grid-connected voltage detection circuit; the high-voltage side of the three-coil transformer is connected to the power grid; the three-coil transformer, the single-switching grid-connected switch K3 located on the stator circuit between the grid-connected detection high voltage PT2 and the three-coil transformer, and the transformer medium-voltage side switch K1 are integrated or not integrated into the cabinet of the enclosure-type unit; The quasi-synchronous grid-connected voltage detection circuit is connected to one end of the stator circuit through the grid-connected detection high voltage PT2. The quasi-synchronous grid-connected voltage detection circuit is connected to the high-voltage side of the three-coil transformer through a set of three-phase low voltages on the secondary side of the high-voltage side of the step-up transformer PT0 and a set of three-phase low voltages on the secondary side of the cascaded transformer PT13, or through a set of three-phase low voltages on the medium-voltage side of the transformer through a capacitive voltage sensor and the first set of three-phase low voltages on the secondary side of the cascaded transformer PT11, or through a set of three-phase low voltages on the secondary side of the transformer low-voltage side PT12.

2. The stator quasi-synchronous grid-connected voltage detection system for doubly-fed wind turbine generators according to claim 1, characterized in that, The rotor circuit is also equipped with a unit auxiliary circuit switch K5, and the power grid is connected to a three-coil transformer or a two-coil transformer through the high-voltage side switch of the unit step-up transformer.

3. A stator quasi-synchronous grid-connected voltage detection system for a doubly-fed wind turbine generator, characterized in that, The system comprises blades and hub, gearbox, and doubly-fed asynchronous generator connected in sequence; wherein, the rotor circuit of the doubly-fed asynchronous generator is connected to the medium-voltage side of the dual-coil transformer through the converter machine-side MPR, the converter DC link, and the converter grid-side NPR; the stator circuit of the doubly-fed asynchronous generator is connected to the medium-voltage side of the dual-coil transformer through a quasi-synchronous grid-connected voltage detection circuit; the high-voltage side of the dual-coil transformer is connected to the power grid; The quasi-synchronous grid-connected voltage detection circuit is connected to one end of the stator circuit through the grid-connected detection high voltage PT2. The quasi-synchronous grid-connected voltage detection circuit is connected to the high-voltage side of the double-coil transformer through a set of three-phase low voltages on the secondary side of the high-voltage side of the step-up transformer PTO and a set of three-phase low voltages on the secondary side of the cascaded transformer PT13, or through a set of three-phase low voltages on the secondary side of the capacitive voltage sensor on the medium-voltage side of the transformer and a set of three-phase low voltages on the secondary side of the cascaded transformer PT11, or through a set of three-phase low voltages on the secondary side of the low-voltage side of the step-up transformer PT12 in the rotor circuit. The dual-coil transformer, the single-switching grid-connected switch K3 and the transformer medium-voltage side switch K1, which are installed on the stator circuit between the grid-connected detection high voltage PT2 and the dual-coil transformer, are integrated or not integrated into the cabinet of the box-type unit.

4. The stator quasi-synchronous grid-connected voltage detection system for doubly-fed wind turbine generators according to claim 3, characterized in that, The rotor circuit is also equipped with a unit auxiliary circuit switch K5, and the power grid is connected to a three-coil transformer or a two-coil transformer through the high-voltage side switch of the unit step-up transformer.

5. A stator quasi-synchronous grid-connected voltage detection system for a doubly-fed wind turbine generator, characterized in that, The system comprises blades and hub, a gearbox, and a doubly-fed asynchronous generator connected in sequence; wherein: The rotor circuit of the doubly-fed asynchronous generator is connected to the low-voltage side of the three-coil transformer via the converter machine-side MPR, the converter DC link, and the converter grid-side NPR; the stator circuit of the doubly-fed asynchronous generator is connected to the medium-voltage side of the three-coil transformer via a quasi-synchronous grid-connected voltage detection circuit; the high-voltage side of the three-coil transformer is connected to the power grid; the quasi-synchronous grid-connected voltage detection circuit is connected to one end of the stator circuit via the grid-connected detection high voltage PT2; the quasi-synchronous grid-connected voltage detection circuit is connected to the high-voltage side of the three-coil transformer via a set of three-phase low voltages on the secondary side of the high-voltage PTO of the step-up transformer and a set of three-phase low voltages on the secondary side of the cascaded transformer PT23, or via a set of three-phase low voltages on the medium-voltage side of the transformer via a capacitive voltage sensor and the first set of three-phase low voltages on the secondary side of the cascaded transformer PT21, or via a set of three-phase low voltages on the secondary side of the transformer low-voltage side PT22; The three-coil transformer, the double-switching grid-connected switch group JC11 / JC12 set on the stator circuit between the grid-connected detection high voltage PT2 and the three-coil transformer, and the transformer medium-voltage side switch K1 / K2 are integrated or not integrated into the cabinet of the box-type unit.

6. The stator quasi-synchronous grid-connected voltage detection system for doubly-fed wind turbine generators according to claim 5, characterized in that, The rotor circuit is also equipped with a unit auxiliary circuit switch K5, and the power grid is connected to a three-coil transformer or a two-coil transformer through the high-voltage side switch of the unit step-up transformer.

7. A stator quasi-synchronous grid-connected voltage detection system for a doubly-fed wind turbine generator, characterized in that, The system comprises blades and hub, gearbox, and doubly-fed asynchronous generator connected in sequence; wherein: the rotor circuit of the doubly-fed asynchronous generator is connected to the medium-voltage side of the double-coil transformer via the converter machine-side MPR, the converter DC link, and the converter grid-side NPR; the stator circuit of the doubly-fed asynchronous generator is connected to the medium-voltage side of the double-coil transformer via a quasi-synchronous grid-connected voltage detection circuit; the high-voltage side of the double-coil transformer is connected to the power grid; the quasi-synchronous grid-connected voltage detection circuit is connected to one end of the stator circuit via the grid-connected detection high voltage PT2; the quasi-synchronous grid-connected voltage detection circuit is connected to the high-voltage side of the double-coil transformer via a set of three-phase low voltages on the secondary side of the high-voltage side of the step-up transformer PTO and two sets of three-phase low voltages on the secondary side of the cascaded transformer PT23, or via a set of three-phase low voltages on the medium-voltage side of the transformer via a capacitive voltage sensor and two sets of three-phase low voltages on the secondary side of the cascaded transformer PT21, or via a set of three-phase low voltages on the secondary side of the low-voltage side of the step-up transformer PT22 in the rotor circuit; The dual-coil transformer, the dual-switching grid-connected switch JC11 / JC12 located on the stator circuit between the grid-connected detection high voltage PT2 and the dual-coil transformer, and the transformer medium-voltage side switch K1 / K2 are integrated or not integrated into the cabinet of the enclosure unit.

8. The stator quasi-synchronous grid-connected voltage detection system for doubly-fed wind turbine generators as described in claim 7, characterized in that, The rotor circuit is also equipped with a unit auxiliary circuit switch K5, and the power grid is connected to a three-coil transformer or a two-coil transformer through the high-voltage side switch of the unit step-up transformer.

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