Power generation system

Abstract

The utility model discloses a power generation system. The power generation system comprises a motor, a transformer and at least two converters, namely a first converter and a second converter, the motor adopts an open winding motor, and the transformer adopts an open winding transformer; the first side of the first converter is connected with the first side of the open-winding motor, and the second side of the first converter is connected with the first side of the open-winding transformer; the first side of the second converter is connected with the second side of the open winding motor, and the second side of the second converter is connected with the second side of the open winding transformer; and the first side and the second side of the open-winding transformer are low-voltage sides of the open-winding transformer. The power generation system can reduce the current of the transformer and the current of the motor, model selection is facilitated, and the cost is reduced.

Description

Technical Field

[0001] The present application relates to the field of power generation technology, and in particular to a power generation system. Background Art

[0002] The converters widely used in power generation systems are three-level converters. As the capacity of power generation systems continues to expand, multiple converters connected in parallel have become a common architecture in power generation systems.

[0003] However, the currents flowing through the parallel converters at the transformer and motor are relatively large, which increases the cost of the transformer and motor, and also poses certain challenges to the cables and circuit breakers. This is not conducive to the selection of the above equipment and will increase costs. Utility Model Content

[0004] In view of this, the present application provides a power generation system that can reduce the current of the transformer and the current of the motor, facilitate selection, and reduce costs.

[0005] The present application provides a power generation system, comprising: a motor, a transformer, and at least two converters: a first converter and a second converter;

[0006] The motor is an open-winding motor, and the transformer is an open-winding transformer;

[0007] A first side of the first converter is connected to a first side of the open-winding motor, and a second side of the first converter is connected to a first side of the open-winding transformer;

[0008] The first side of the second converter is connected to the second side of the open-winding motor, and the second side of the second converter is connected to the second side of the open-winding transformer; the first side and the second side of the open-winding transformer are both low-voltage sides of the open-winding transformer.

[0009] A possible implementation method further includes a grid-side filtering circuit;

[0010] A first end of the grid-side filter loop is connected to a second side of the first converter, and a second end of the grid-side filter loop is connected to a first side of the open-winding transformer;

[0011] A third end of the grid-side filter loop is connected to the second side of the second converter, and a fourth end of the grid-side filter loop is connected to the second side of the open-winding transformer.

[0012] A possible implementation method further includes a machine-side filtering circuit;

[0013] A first end of the machine-side filter circuit is connected to a first side of the open-winding motor, and a second end of the machine-side filter circuit is connected to a first side of the first converter;

[0014] The third end of the machine-side filtering circuit is connected to the second side of the open-winding motor, and the fourth end of the machine-side filtering circuit is connected to the first side of the second converter.

[0015] In a possible implementation, when the power generation system is a doubly-fed power generation system, the open-winding motor is an open-winding doubly-fed motor, and the open-winding doubly-fed motor includes a stator side and a rotor side; the power generation system further includes: a three-phase transformer;

[0016] The first side of the three-phase transformer is connected to the stator side of the open-winding doubly-fed motor, and the second side of the three-phase transformer is connected to the high-voltage side of the open-winding transformer;

[0017] The rotor side of the open-winding doubly-fed motor includes a first rotor-side port and a second rotor-side port. The first rotor-side port is connected to the first end of the machine-side filtering circuit, and the second rotor-side port is connected to the third end of the machine-side filtering circuit.

[0018] In a possible implementation, the phase of the voltage on the second side of the first converter is opposite to the phase of the voltage on the second side of the second converter.

[0019] In a possible implementation, both the first converter and the second converter are two-level converters;

[0020] Or, both the first converter and the second converter are three-level converters.

[0021] In a possible implementation, the first converter is a neutral-point-clamped three-level converter or an active neutral-point-clamped three-level converter;

[0022] The second converter is a neutral-point-clamped three-level converter or an active neutral-point-clamped three-level converter.

[0023] In a possible implementation, the machine-side filtering circuit includes: a first group of inductors, a second group of inductors, a first group of resistors, and a first group of capacitors;

[0024] The first group of inductors is connected between the first end and the second end of the machine-side filtering circuit;

[0025] The second group of inductors is connected between the third end and the fourth end of the machine-side filtering circuit;

[0026] The first group of resistors and the first group of capacitors are connected in series between the second end and the fourth end of the machine-side filtering circuit.

[0027] In a possible implementation, the machine-side filtering circuit includes: a first group of inductors, a first group of resistors, and a first group of capacitors;

[0028] The first group of inductors is connected between the first end and the second end of the machine-side filtering circuit;

[0029] The first group of resistors and the first group of capacitors are connected in series between the second end and the fourth end of the machine-side filtering circuit.

[0030] A possible implementation, the grid-side filtering circuit includes: a third group of inductors, a fourth group of inductors and a second group of capacitors;

[0031] The third group of inductors is connected between the first end and the second end of the grid-side filtering circuit;

[0032] The fourth group of inductors is connected between the third end and the fourth end of the grid-side filtering circuit;

[0033] The second group of capacitors is connected between the second end and the fourth end of the grid-side filtering circuit.

[0034] A possible implementation, the grid-side filtering circuit includes: a third group of inductors and a second group of capacitors;

[0035] The third group of inductors is connected between the first end and the second end of the grid-side filtering circuit;

[0036] The second group of capacitors is connected between the second end and the fourth end of the grid-side filtering circuit.

[0037] The power generation system provided by the embodiment of the present application adopts an open-winding motor and an open-winding transformer. The open-winding motor is respectively connected to a first converter and a second converter at both ends of the open winding. The open-winding transformer is respectively connected to the first converter and the second converter at both ends of the open winding. When the two converters are connected in series, the voltage acting on the open-winding motor and the open-winding transformer is about twice the input voltage and the output voltage of the traditional parallel converter. In this way, the current is reduced to 1 / 2, thereby reducing the current stress of the transformer and the current stress of the motor, improving the performance, facilitating the selection of the transformer and the motor, and reducing the cost. Description of the Drawings

[0038] Figure 1 It is a schematic diagram of a wind turbine provided by an embodiment of the present application;

[0039] Figure 2 It is a schematic diagram of another wind turbine provided by an embodiment of the present application;

[0040] Figure 3 It is a schematic diagram of a wind turbine provided by an embodiment of the present application;

[0041] Figure 4 It is a schematic diagram of a machine-side filtering circuit provided by an embodiment of the present application;

[0042] Figure 5 Schematic diagram of another machine-side filtering circuit provided by an embodiment of the present application;

[0043] Figure 6 Schematic diagram of a grid-side filtering circuit provided by an embodiment of the present application;

[0044] Figure 7 Schematic diagram of another grid-side filtering circuit provided by an embodiment of the present application;

[0045] Figure 8 Schematic diagram of a neutral-point clamped three-level converter provided by an embodiment of the present application;

[0046] Figure 9 Schematic diagram of an active neutral-point clamped three-level converter provided by an embodiment of the present application. Detailed implementation manners

[0047] To make the above objects, features, and advantages of the present application more obvious and understandable, the following further describes the embodiments of the present application in detail with reference to the drawings and specific implementation manners.

[0048] The power generation system provided by the embodiments of the present application can be applied to a wind power generation system or a hydroelectric power generation system, and no specific limitation is made here. For example, in a hydroelectric power generation scenario, a doubly-fed motor can be applied in a hydroelectric power generation system. For the convenience of understanding, the following takes a wind power generation system as an example for introduction.

[0049] See Figure 1 , which is a schematic diagram of a wind power generation system provided by an embodiment of the present application.

[0050] The wind power generation system provided by the embodiments of the present application includes: a motor, a transformer, and at least two converters below: a first converter 3 and a second converter 4;[[ID=�5]]

[0051] The motor adopts an open-winding motor 1, and the transformer adopts an open-winding transformer 6;

[0052] The first side of the first converter 3 is connected to the first side of the open-winding motor 1, and the second side of the first converter 3 is connected to the first side of the open-winding transformer 6.

[0053] The first side of the second converter 4 is connected to the second side of the open-winding motor 1, and the second side of the second converter 4 is connected to the second side of the open-winding transformer 6.

[0054] For example, in a full-power wind power generation system, the neutral point of the motor winding is opened to form the following series circuit: the first converter 3 and the second converter 4 are boosted by the open-winding transformer 6 and then merged into the power grid. For example, the open-winding transformer is boosted to 35 kV. The low-voltage side of the open-winding transformer is an open winding, and the high-voltage side is star-connected or delta-connected.

[0055] The wind power generation system provided by the embodiment of the present application adopts an open-winding motor and an open-winding transformer. The open-winding motor is respectively connected to a first converter and a second converter at both ends of the open winding. The open-winding transformer is respectively connected to the first converter and the second converter at both ends of the open winding. When the two converters are connected in series, the voltage acting on the open-winding motor and the open-winding transformer is about twice the input voltage and the output voltage of the traditional parallel converter. In this way, the current is reduced to 1 / 2, thereby reducing the current stress of the transformer and the current stress of the motor, improving the performance, facilitating the selection of the transformer and the motor, and reducing the cost. Since the two converters in the traditional power generation system are connected in parallel to the motor and the transformer, the voltage of the motor is consistent with the input voltage of the converter, and the voltage of the low-voltage side of the transformer is consistent with the output voltage of the converter. However, in the power generation system provided by the present application, the two converters are connected in series. Therefore, the voltage applied to the open-winding motor is the sum of the voltages on the first sides of the two converters, and the voltage applied to the low-voltage side of the open-winding transformer is the sum of the voltages on the second sides of the two converters, which is equivalent to that the voltage acting on the open-winding motor and the open-winding transformer is about twice the input voltage and the output voltage of the traditional parallel converter.

[0056] For example, when the solution provided by the embodiment of the present application is applied to a wind power generation system of more than 10 MW, the voltage at the connection points of the motor and the transformer to the converter can be increased by about twice on the original basis, reducing the current. The reduction of the current can significantly save the copper loss. When using IGBT devices with higher withstand voltage to upgrade the three-level converter to an input voltage and an output voltage with an effective value of about 1650 V, the cables and circuit breakers used can use standard components of the general voltage level of 3300 V, which can further reduce the cost at high power.

[0057] For an MW-class transformer, the short-circuit impedance is generally about 10%. After the voltage on the machine side of the transformer rises by twice, the leakage inductance can be increased by 4 times. When the leakage inductance is large, capacitors with smaller capacitance values and inductors with smaller inductance values can be selected, which is beneficial to reducing the volume and cost of the capacitors and inductors, and thus can reduce the cost of the converter filtering.

[0058] When the two converters work in a three-level mode respectively, they are five-level relative to the motor and the transformer. If the same equivalent switching frequency is maintained, the switching loss of the converter can be reduced.

[0059] In a possible implementation manner, in the wind power generation system provided by the embodiment of the present application, both the first converter 3 and the second converter 4 are three-level converters. In addition, the two converters can also be converters with other numbers of levels. For example, both the first converter 3 and the second converter 4 are two-level converters, which are not specifically limited herein.

[0060] SeeFigure 2 , this figure is a schematic diagram of another wind power generation system provided by an embodiment of the present application.

[0061] To achieve filtering, the wind power generation system provided by the embodiment of the present application further includes a machine-side filtering circuit 2;

[0062] The first end 11 of the machine-side filtering circuit 2 is connected to the first side of the open-winding motor 1, and the second end 22 of the machine-side filtering circuit 2 is connected to the first side of the first converter 3;

[0063] The third end 33 of the machine-side filtering circuit 2 is connected to the second side of the open-winding motor 1, and the fourth end 44 of the machine-side filtering circuit 2 is connected to the first side of the second converter 4.

[0064] The wind power generation system further includes a grid-side filtering circuit 5; the first end 51 of the grid-side filtering circuit 5 is connected to the second side of the first converter 3, and the second end 52 of the grid-side filtering circuit 5 is connected to the first side of the open-winding transformer 6;

[0065] The third end 53 of the grid-side filtering circuit 5 is connected to the second side of the second converter 4, and the fourth end 54 of the grid-side filtering circuit 5 is connected to the second side of the open-winding transformer 6.

[0066] The open-winding transformer 6 has a high-voltage side and a low-voltage side. Among them, the low-voltage side has two ports, and the two ports on the low-voltage side are respectively connected to the two output ends of the grid-side filtering circuit. The high-voltage side has one port, and the port on the high-voltage side is used to connect to the power grid.

[0067] In a possible implementation, the phase of the voltage on the second side of the first converter and the phase of the voltage on the second side of the second converter are opposite. Opposite phases mean that the phase difference between the voltages on the grid sides of the first converter and the second converter is 180 degrees. The present application does not strictly limit it to 180 degrees. As long as the phase difference between the grid-side voltages of the two converters is within the allowable tolerance range, it is regarded as having opposite phases. For example, 179 degrees, 181 degrees, etc. are all regarded as 180 degrees.

[0068] Figure 1 and Figure 2 As shown in the figure is a full-power wind power generation system. Now, the implementation situation when the power generation system is a doubly-fed power generation system will be introduced. Continuing with the wind power generation scenario as an example, that is, the doubly-fed power generation system is a doubly-fed wind power generation system, and the open-winding motor therein is an open-winding doubly-fed motor.

[0069] See Figure 3 , this figure is a schematic diagram of a wind power generation system provided by an embodiment of the present application.

[0070] When the wind power generation system provided by the embodiment of the present application is a doubly-fed wind power generation system, the wind power generation system further includes: a three-phase transformer 8; it should be understood that the three-phase transformer 8 is a conventional transformer and not an open-winding transformer.

[0071] It should be understood that for the open-winding doubly-fed motor 7 in the doubly-fed wind power generation system, which includes a stator side and a rotor side, the stator side of the open-winding doubly-fed motor 7 is connected to the first side of the three-phase transformer 8, and the second side of the three-phase transformer 8 is connected to the high-voltage side of the open-winding transformer 6.

[0072] The rotor side of the open-winding doubly-fed motor 7 includes two ports, namely the first rotor-side port and the second rotor-side port. The first rotor-side port of the open-winding doubly-fed motor 7 is connected to the first end of the machine-side filter circuit 2, and the second rotor-side port of the open-winding doubly-fed motor 7 is connected to the third end of the machine-side filter circuit 2.

[0073] The following introduces two implementation methods of the machine-side filter circuit in conjunction with the accompanying drawings. It should be understood that the machine-side filter circuits provided in the following embodiments are applicable to the full-power wind power generation system and the doubly-fed wind power generation system.

[0074] See Figure 4 , which is a schematic diagram of a machine-side filter circuit provided by an embodiment of the present application.

[0075] For the wind power generation system provided by the embodiment of the present application, the machine-side filter circuit includes: the first group of inductors L1, the second group of inductors L2, the first group of resistors R, and the first group of capacitors C1; it should be understood that the above "group" means three in three phases, that is, each phase includes one.

[0076] The first group of inductors L1 is connected between the first end and the second end of the machine-side filter circuit;

[0077] The second group of inductors L2 is connected between the third end and the fourth end of the machine-side filter circuit;

[0078] The first group of resistors R and the first group of capacitors C1 are connected in series between the second end and the fourth end of the machine-side filter circuit.

[0079] The machine-side filter circuit provided by the embodiment of the present application can be compatible with the traditional three-level converter.

[0080] The following introduces another machine-side filter circuit.

[0081] See Figure 5 , which is a schematic diagram of another machine-side filter circuit provided by an embodiment of the present application.

[0082] For the wind power generation system provided by the embodiment of the present application, the machine-side filter circuit includes: the first group of inductors L1, the first group of resistors R, and the first group of capacitors C1;

[0083] The first group of inductors L1 is connected between the first end and the second end of the machine-side filter circuit;

[0084] The first group of resistors R and the first group of capacitors C1 are connected in series and then connected between the second end and the fourth end of the machine-side filtering circuit.

[0085] The machine-side filtering circuit provided by the embodiment of the present application includes an LC filtering circuit. Compared with the Figure 4 LCL filtering circuit, one group of inductors can be saved, and the cost can be reduced and the volume can be decreased.

[0086] The implementation manner of the grid-side filtering circuit will be introduced below with reference to the drawings.

[0087] See Figure 6 , which is a schematic diagram of a grid-side filtering circuit provided by the embodiment of the present application.

[0088] For the wind power generation system provided by the embodiment of the present application, the grid-side filtering circuit includes: the third group of inductors L3, the fourth group of inductors L4, and the second group of capacitors C2;

[0089] The third group of inductors L3 is connected between the first end and the second end of the machine-side filtering circuit;

[0090] The fourth group of inductors L4 is connected between the third end and the fourth end of the machine-side filtering circuit;

[0091] The second group of capacitors C2 is connected between the second end and the fourth end of the machine-side filtering circuit.

[0092] The grid-side filtering circuit provided by the embodiment of the present application can be compatible with the traditional three-level converter.

[0093] Another grid-side filtering circuit will be introduced below.

[0094] See Figure 7 , which is a schematic diagram of another grid-side filtering circuit provided by the embodiment of the present application.

[0095] For the wind power generation system provided by the embodiment of the present application, the machine-side filtering circuit includes: the third group of inductors L3 and the second group of capacitors C2;

[0096] The third group of inductors L3 is connected between the first end and the second end of the machine-side filtering circuit;

[0097] The second group of capacitors C2 is connected between the second end and the fourth end of the machine-side filtering circuit.

[0098] The machine-side filtering circuit provided by the embodiment of the present application includes an LC filtering circuit. Compared with the Figure 6 LCL filtering circuit, one group of inductors can be saved, and the cost can be reduced and the volume can be decreased.

[0099] The wind power generation system according to the embodiments of the present application does not specifically limit the specific topology of the three-level converter. For example, the first converter is a neutral point clamped three-level converter or an active neutral point clamped three-level converter; the second converter is a neutral point clamped three-level converter or an active neutral point clamped three-level converter.

[0100] Specifically, reference can be made to Figure 8 the neutral point clamped three-level converter NPC shown in Figure 9 and the active neutral point clamped three-level converter ANPC shown in

[0101] It should be noted that the embodiments in this specification are described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the methods disclosed in the embodiments, since they correspond to the product embodiments disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the product embodiment part.

[0102] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A power generation system, characterized in that, Comprising: A motor, a transformer, and at least two of the following converters: a first converter and a second converter; The motor is an open-winding motor, and the transformer is an open-winding transformer; A first side of the first converter is connected to a first side of the open-winding motor, and a second side of the first converter is connected to a first side of the open-winding transformer; A first side of the second converter is connected to a second side of the open-winding motor, and a second side of the second converter is connected to a second side of the open-winding transformer; both the first side and the second side of the open-winding transformer are low-voltage sides of the open-winding transformer.

2. The power generation system according to claim 1, wherein It further includes a grid-side filter circuit; A first end of the grid-side filter circuit is connected to the second side of the first converter, and a second end of the grid-side filter circuit is connected to the first side of the open-winding transformer; A third end of the grid-side filter circuit is connected to the second side of the second converter, and a fourth end of the grid-side filter circuit is connected to the second side of the open-winding transformer.

3. The power generation system according to claim 2, wherein It further includes a machine-side filter circuit; A first end of the machine-side filter circuit is connected to the first side of the open-winding motor, and a second end of the machine-side filter circuit is connected to the first side of the first converter; A third end of the machine-side filter circuit is connected to the second side of the open-winding motor, and a fourth end of the machine-side filter circuit is connected to the first side of the second converter.

4. The power generation system according to claim 3, wherein When the power generation system is a doubly-fed power generation system, the open-winding motor is an open-winding doubly-fed motor, and the open-winding doubly-fed motor includes a stator side and a rotor side; the power generation system further includes: a three-phase transformer; A first side of the three-phase transformer is connected to the stator side of the open-winding doubly-fed motor, and a second side of the three-phase transformer is connected to the high-voltage side of the open-winding transformer; The rotor side of the open-winding doubly-fed motor includes a first rotor-side port and a second rotor-side port, the first rotor-side port is connected to the first end of the machine-side filter circuit, and the second rotor-side port is connected to the third end of the machine-side filter circuit.

5. The power generation system according to any one of claims 1-3, characterized in that, The phase of the voltage on the second side of the first converter is opposite to the phase of the voltage on the second side of the second converter.

6. The power generation system according to any one of claims 1-3, characterized in that, Both the first converter and the second converter are two-level converters; Or, both the first converter and the second converter are three-level converters.

7. The power generation system according to claim 6, characterized in that, The first converter is a neutral-point clamped three-level converter or an active neutral-point clamped three-level converter; The second converter is a neutral-point clamped three-level converter or an active neutral-point clamped three-level converter.

8. The power generation system according to claim 3, characterized in that, The machine-side filter circuit includes: a first group of inductors, a second group of inductors, a first group of resistors, and a first group of capacitors; The first group of inductors is connected between the first end and the second end of the machine-side filter circuit; The second group of inductors is connected between the third end and the fourth end of the machine-side filter circuit; The first group of resistors and the first group of capacitors are connected in series between the second end and the fourth end of the machine-side filter circuit.

9. The power generation system according to claim 3, wherein The machine-side filter circuit includes: a first group of inductors, a first group of resistors, and a first group of capacitors; The first group of inductors is connected between the first end and the second end of the machine-side filter circuit; The first group of resistors and the first group of capacitors are connected in series between the second end and the fourth end of the machine-side filter circuit.

10. The power generation system according to claim 4, characterized in that, The grid-side filtering circuit includes: a third group of inductors, a fourth group of inductors, and a second group of capacitors; The third group of inductors is connected between the first end and the second end of the grid-side filtering circuit; The fourth group of inductors is connected between the third end and the fourth end of the grid-side filtering circuit; The second group of capacitors is connected between the second end and the fourth end of the grid-side filtering circuit.

11. The power generation system according to claim 4, characterized in that, The grid-side filtering circuit includes: a third group of inductors and a second group of capacitors; The third group of inductors is connected between the first end and the second end of the grid-side filtering circuit; The second group of capacitors is connected between the second end and the fourth end of the grid-side filtering circuit.

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