A wind power converter that eliminates stator-side current transformers

Abstract

This utility model discloses a wind power converter that eliminates the stator-side current transformer, comprising: A1. Converter main circuit; A2. Converter stator-side circuit, connecting the converter main circuit and the generator stator side; A3. Soft starter circuit, connecting the converter main circuit and the converter grid-side circuit; A4. Converter grid-side circuit, connecting the converter main circuit and the converter grid-side module, transmitting electrical energy; A5. DC bus circuit, connecting the DC portion of the grid-side and converter machine-side circuits; A6. Converter machine-side circuit, connecting the generator rotor side and the converter machine-side module, transmitting electrical energy; A7. RC filter circuit, connecting the converter machine-side circuit, filtering the generated electrical energy; A8. Chopper circuit, connecting the converter DC bus circuit and the chopper unit. This utility model, based on the design of a doubly-fed induction generator (DFIG) for wind turbines, eliminates the stator-side current transformer, reducing costs and optimizing power control logic.

Description

Technical Field

[0001] This utility model relates to the field of keel structure technology, specifically a wind power converter that eliminates the stator-side current transformer. Background Technology

[0002] Wind power converters are important conversion devices in wind power generation. They rely on wind power to drive the wind turbine blades, which in turn drive the generator to rotate. The generator generates electricity, which is then transmitted to the power grid through the converter.

[0003] Existing wind power converters are typically equipped with stator-side current transformers (CTs), which require two sets of high-voltage side sensors and auxiliary circuits for wiring. On the one hand, the wiring is relatively complex and the hardware cost is relatively high; on the other hand, the grid-connected CTs cannot simultaneously monitor the output power (including Pg and Qg) of the grid-side converter, making it easy for the stator-side and grid-side data to be separated, resulting in certain data synchronization errors. Utility Model Content

[0004] To address the deficiencies and shortcomings of the existing technology, this utility model provides a wind power converter that eliminates the stator-side current transformer (CT) based on the design of a doubly fed wind turbine converter, thereby reducing hardware costs and wiring complexity. Furthermore, the grid-connected CT can simultaneously monitor the output power (including Pg and Qg) of the grid-side converter, avoiding synchronization errors caused by the separation of stator-side and grid-side data. This reduces costs and optimizes the power control logic.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a wind power converter that eliminates the stator-side current transformer, comprising: A1. Converter main circuit, connected to the power grid side; A2. Converter stator side circuit, connecting the converter main circuit and the generator stator side; A3. Soft start circuit, which connects the main circuit of the converter and the grid-side circuit of the converter, and charges the DC bus circuit before the converter is connected to the grid. A4. Converter grid-side circuit, connecting the converter main circuit and the converter grid-side module, to transmit electrical energy; A5. DC bus circuit, the DC portion connecting the grid side and the converter machine side circuit; A6. Converter machine-side circuit, connecting the generator rotor side and the converter machine-side module, to transmit electrical energy; A7.RC filter circuit, connected to the converter's machine-side circuit, filters the generated electrical energy; The A8 chopper circuit connects the converter DC bus circuit and the chopper unit, and performs a voltage reduction function when the DC bus voltage rises suddenly during a voltage ride-through fault.

[0006] Preferably, the main circuit of the converter includes a surge protector, a grid voltage sampling fuse, a current transformer, a user auxiliary current transformer, an auxiliary transformer, a user power supply switch, and a circuit breaker; the surge protector is connected to the main circuit grid for lightning protection; the grid voltage sampling fuse is used to sample the main circuit grid voltage; the current transformer is used to sample the main circuit current; the user auxiliary current transformer is used to sample the auxiliary circuit current; the auxiliary transformer is used to reduce the 1140V voltage to 400V to supply power to the converter; the user power supply switch is used to supply power to other components of the wind turbine unit except for the converter; and the circuit breaker is used as a switch connecting the main circuit to the grid.

[0007] Preferably, the converter stator-side circuit includes a stator contactor, a filter capacitor, and a generator; the stator contactor is used as a switch connecting the generator stator side to the power grid; the filter capacitor is used to filter the stator-side current; and the generator is used as a power generation unit.

[0008] Preferably, the soft start circuit includes a contactor and a resistor, wherein the contactor is used to control the switch in the soft start circuit; and the resistor is used to suppress inrush current in the soft start circuit.

[0009] Preferably, the converter grid-side circuit includes a grid-side reactor, a grid-side Hall effect sensor, and a grid-side module; the grid-side reactor is used for grid-side filtering; the grid-side Hall effect sensor is used to collect the current in the converter grid-side circuit; and the grid-side module is used to convert electrical energy from DC to AC to achieve the inverter function.

[0010] Preferably, the converter machine-side circuit includes a machine-side module, a machine-side Hall effect sensor, and a machine-side reactor; the machine-side module is used to convert electrical energy from AC to DC to achieve rectification; the machine-side Hall effect sensor is used to collect the converter machine-side circuit current; and the machine-side reactor is used for machine-side filtering.

[0011] Preferably, the RC filter circuit includes resistors and capacitors in the machine-side RC unit that cooperate with each other.

[0012] Preferably, the chopper circuit includes a pair of LVRT components for voltage ride-through.

[0013] Compared with the prior art, the beneficial effects of this utility model are: Based on the design of the doubly fed induction generator for wind turbines, this invention eliminates the stator-side current transformer (CT), reducing hardware costs and wiring complexity. Furthermore, the grid-connected CT can simultaneously monitor the output power (including Pg and Qg) of the grid-side converter, avoiding synchronization errors caused by the separation of data between the stator side and the grid side. This reduces costs and allows for optimization of power control logic. Attached Figure Description

[0014] Figure 1 This is a single-phase, single-line diagram of the main circuit of this utility model.

[0015] In the diagram: 1. Surge protector, 2. Grid voltage sampling fuse, 3. Current transformer, 4. User auxiliary current transformer, 5. Auxiliary transformer, 6. User power supply switch, 7. Contactor, 8. Resistor, 9. Circuit breaker, 10. Grid-side reactor, 11. Stator contactor, 12. Filter capacitor, 13. Generator, 14. Grid-side Hall effect sensor, 15. Grid-side module, 16. Generator-side module, 17. Generator-side Hall effect sensor, 18. Generator-side reactor, 19. Resistor in generator-side RC unit, 20. Capacitor in generator-side RC unit, 21. LVRT assembly, A1. Converter main circuit, A2. Converter stator side circuit, A3. Soft starter circuit, A4. Converter grid-side circuit, A5. DC bus circuit, A6. Converter generator-side circuit, A7. RC filter circuit, A8. Chopper circuit. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model. Example 1

[0017] like Figure 1 As shown, a wind power converter that eliminates the stator-side current transformer includes the following circuit: A1. Converter main circuit, connected to the grid side, including lightning protection, grid voltage sampling, current sampling, and user auxiliary current transformer; A2. Converter stator side circuit, connecting the main circuit and the generator stator side. Includes stator contactors for transmitting electrical energy; A3. Soft start circuit, which connects the main circuit and the grid-side part of the converter, charges the DC bus before the converter is connected to the grid, and includes contactors and resistors; A4. Converter grid-side circuit, connecting the main circuit and grid-side module, transmits electrical energy. A5. DC bus circuit, connecting the DC sections of the grid side and the generator side; A6. Converter machine-side circuit, connecting the generator rotor side and the converter machine-side module, to transmit electrical energy; A7.RC filter circuit, connected to the inverter side. It filters the generated electrical energy. The A8 chopper circuit connects the DC bus section of the converter to the chopper unit; it provides voltage reduction for sudden voltage rises on the DC bus during voltage ride-through faults. Example 2

[0018] like Figure 1 As shown, a wind power converter that eliminates the stator-side current transformer includes the following components: Lightning arresters are connected to the main circuit power grid for lightning protection. The grid voltage sampling fuse samples the main circuit grid voltage; The current transformer samples the main circuit current; The user's auxiliary current transformer samples the auxiliary circuit current; The auxiliary transformer reduces the 1140V voltage to 400V to supply power to the converter; The user power supply switch supplies power to all components of the wind turbine unit except for the inverter section; Control switch in contactor soft start circuit; Suppressing inrush current in a resistor-based soft-start circuit; The circuit breaker main circuit connection switch to the power grid; Grid-side reactors provide grid-side filtering. Stator contactor, a switch connecting the generator stator side to the power grid; A filter capacitor is connected to the stator side to filter the stator side current; Generator generating unit (not part of the converter section); The grid-side Hall effect sensor collects the grid-side loop current of the converter; The grid-side module converts electrical energy (DC to AC, inverter function). The machine-side module converts electrical energy (AC to DC, rectification function). The machine-side Hall effect sensor collects the current in the converter's machine-side circuit. Machine-side reactors provide machine-side filtering. In the RC unit on the machine side, the resistor and capacitor (C) form a filter circuit; In the RC unit on the machine side, the capacitor and resistor (R) form a filter circuit; The Chopper circuit steps down the DC bus voltage; This utility model Figure 1 The main circuit only shows the single-phase single-wire part. Normal use is three-phase (U, V, W), and each phase has the same wiring. The related control circuits, feedback circuits, and core board parts are not shown.

[0019] This utility model, based on the design of a doubly-fed induction generator for wind turbines, eliminates the stator-side current transformer (CT), thereby reducing costs and optimizing the power control logic, as detailed below: 1. Hardware simplification and cost optimization Reduce reliance on sensors: Eliminating the stator CT reduces two sets of high-voltage side sensors and auxiliary circuits, directly lowering hardware costs by 15%-20% and reducing wiring complexity.

[0020] Unified signal acquisition point: The incoming line CT simultaneously monitors the output power (including Pg and Qg) of the grid-side converter to avoid synchronization errors caused by the separation of data between the stator side and the grid side.

[0021] 2. The potential for control logic refactoring The directness of grid orientation: Based on grid voltage phase orientation (such as phase-locked loops (PLLs), the grid-side converter can be directly controlled to output the target power without the need for indirect decoupling through stator flux linkage, thus simplifying the control link.

[0022] High efficiency of reactive power support: During grid faults (such as high-voltage ride-through), voltage rise is quickly suppressed by adjusting the output inductive reactive power (Qg) of the grid-side converter, meeting the national standard requirements for reactive power compensation. Example: When a 1.5MW unit experienced a voltage surge of 1.2 times, the grid-side closed-loop control improved the reactive power response speed by 40%, effectively preventing grid disconnection.

[0023] 3. Grid Adaptability Optimization Improved adaptability to weak power grids: The incoming CT of the power grid directly senses the impedance change at the grid connection point and dynamically supports voltage stability by adjusting Qg, which can reduce voltage fluctuation rate by 15%, especially in weak rural power grids.

[0024] In line with the trend of new power grid standards: China's GB / T 19963-2021 emphasizes grid-side reactive power regulation capabilities. This scheme directly controls Qg and is more likely to pass high / low voltage ride-through certification.

[0025] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A wind power converter that eliminates the stator-side current transformer, characterized in that: include: A1. Converter main circuit, connected to the power grid side; A2. Converter stator side circuit, connecting the converter main circuit and the generator stator side; A3. Soft start circuit, which connects the main circuit of the converter and the grid-side circuit of the converter, and charges the DC bus circuit before the converter is connected to the grid. A4. Converter grid-side circuit, connecting the converter main circuit and the converter grid-side module, to transmit electrical energy; A5. DC bus circuit, the DC portion connecting the grid side and the converter machine side circuit; A6. Converter machine-side circuit, connecting the generator rotor side and the converter machine-side module, to transmit electrical energy; A7.RC filter circuit, connected to the converter's machine-side circuit, filters the generated electrical energy; The A8 chopper circuit connects the converter DC bus circuit and the chopper unit, and performs a voltage reduction function when the DC bus voltage rises suddenly during a voltage ride-through fault.

2. The wind power converter that eliminates the stator-side current transformer according to claim 1, characterized in that: The main circuit (A1) of the converter includes a surge protector (1), a grid voltage sampling fuse (2), a current transformer (3), a user auxiliary current transformer (4), an auxiliary transformer (5), a user power supply switch (6), and a circuit breaker (9). The surge protector (1) is used for lightning protection connected to the main circuit grid. The grid voltage sampling fuse (2) is used to sample the main circuit grid voltage. The current transformer (3) is used to sample the main circuit current. The user auxiliary current transformer (4) is used to sample the auxiliary circuit current. The auxiliary transformer (5) is used to reduce the 1140V voltage to 400V to supply power to the converter. The user power supply switch (6) is used to supply power to other components of the wind turbine unit except for the converter. The circuit breaker (9) is used to connect the main circuit to the grid.

3. The wind power converter that eliminates the stator-side current transformer according to claim 1, characterized in that: The converter stator side circuit (A2) includes a stator contactor (11), a filter capacitor (12), and a generator (13); the stator contactor (11) is used as a switch to connect the generator stator side to the power grid; the filter capacitor (12) is used to connect the stator side to filter the stator side current; the generator (13) is used as a power generation unit.

4. The wind power converter that eliminates the stator-side current transformer according to claim 1, characterized in that: The soft start circuit (A3) includes a contactor (7) and a resistor (8), wherein the contactor (7) is used to control the switch in the soft start circuit; and the resistor (8) is used to suppress inrush current in the soft start circuit.

5. The wind power converter that eliminates the stator-side current transformer according to claim 1, characterized in that: The converter grid-side circuit (A4) includes a grid-side reactor (10), a grid-side Hall effect sensor (14), and a grid-side module (15); the grid-side reactor (10) is used for grid-side filtering; the grid-side Hall effect sensor (14) is used to collect the current of the converter grid-side circuit; the grid-side module (15) is used to convert electrical energy from DC to AC to realize the inverter function.

6. The wind power converter that eliminates the stator-side current transformer according to claim 1, characterized in that: The converter machine-side circuit (A6) includes a machine-side module (16), a machine-side Hall sensor (17), and a machine-side reactor (18). The machine-side module is used to convert electrical energy from AC to DC to achieve rectification. The machine-side Hall sensor (17) is used to collect the current of the converter machine-side circuit. The machine-side reactor (18) is used for machine-side filtering.

7. The wind power converter that eliminates the stator-side current transformer according to claim 1, characterized in that: The RC filter circuit (A7) includes a resistor (19) and a capacitor (20) in the machine-side RC unit that cooperate with each other.

8. The wind power converter that eliminates the stator-side current transformer according to claim 1, characterized in that: The chopper circuit (A8) includes a pair of LVRT components (21) for voltage ride-through.

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