CN204498036U - A kind of excitation unit of double-fed wind power generator - Google Patents

Abstract

An excitation device for a doubly-fed wind power generating set, including a doubly-fed asynchronous wind power generator, a rotor-side converter, a driver, an excitation current controller, a DC-side buffer capacitor, a battery pack, an AC terminal of the rotor-side converter and a dual The rotor winding of the fed asynchronous wind turbine is connected, the DC terminal of the rotor-side converter is connected to the battery pack, the rotor-side converter is also connected to a driver, and the driver is connected to an excitation current controller. Between the rotor-side converter and the battery A buffer capacitor on the DC side is connected in parallel to the DC bus, the stator winding of the double-fed asynchronous wind generator is connected to the grid, and the wind turbine is connected to the shaft of the double-fed asynchronous wind generator through a gearbox. The utility model gets rid of the dependence on the power grid, so the generator can also be started when the power grid is not charged, and can also run independently with load. At the same time, the stator-side converter of the traditional doubly-fed wind power generator is omitted, so that the structure and control become simple, and the cost is saved at the same time.

Description

A kind of excitation device of doubly-fed wind power generator

technical field

The utility model relates to an excitation device for a generator, in particular to an excitation device for a double-fed wind power generating set.

Background technique

In traditional doubly-fed wind turbines, the stator is connected to the grid directly or through a step-up transformer, and the rotor is connected to the grid through a converter. When the double-fed asynchronous wind turbine is started, the rotor excitation power is provided by the grid, which is converted into DC by the grid-side converter, and then converted into AC by the rotor-side converter and connected to the generator rotor. Among them, the amplitude, phase and frequency of the rotor excitation current are controlled by the excitation current controller, so as to complete grid connection and power control.

From the working process of the doubly-fed asynchronous wind generator, it can be seen that if the grid is not live, it will not be able to provide excitation power for the rotor, resulting in the failure of the generator to start. Small doubly-fed wind turbines used in microgrids or other fields sometimes need to run independently with loads away from the grid.

In the existing doubly-fed asynchronous wind generators that can operate independently from the grid, there is a solution that is to connect batteries in parallel on the DC side of the converter without changing the topology of the traditional converter. After starting, remove the battery after starting. During the operation of the motor, the excitation power is still provided by the stator, but the excitation power is not stable and independent. If the stator voltage fluctuates greatly during independent operation with load, it will affect the control of the excitation current, thereby affecting the operation of the generator.

Invention content

The purpose of this utility model is to overcome the above disadvantages and provide an excitation device for a doubly-fed wind power generating set, which separates the generator stator from the rotor circuit, and the battery independently provides excitation current for the rotor. Therefore, the doubly-fed asynchronous wind generator can be started when the grid is not powered or run independently with load.

In order to solve the above technical problems, the technical solution adopted by the utility model is: an excitation device of a doubly-fed wind power generating set, including a doubly-fed asynchronous wind power generator, a rotor-side converter, a driver, an excitation current controller, a DC side Buffer capacitors, battery packs, the AC end of the rotor-side converter is connected to the rotor winding of the doubly-fed asynchronous wind turbine, the DC end of the rotor-side converter is connected to the battery pack, and the rotor-side converter is also connected to the driver, the driver It is connected with an excitation current controller, and a DC-side buffer capacitor is set between the rotor-side converter and the battery in parallel on the DC bus. The stator winding of the doubly-fed asynchronous wind turbine is connected to the power grid. Shaft connections for wind turbines.

A charging and discharging controller is also provided between the storage battery and the DC side buffer capacitor.

A rotary encoder is provided between the doubly-fed asynchronous wind generator and the gearbox, a stator voltage detector is provided between the doubly-fed asynchronous wind generator and the power grid, and a stator voltage detector is provided between the doubly-fed asynchronous wind generator and the rotor-side converter. A rotor current detector is provided, and a DC voltage detector is also provided between the rotor side converter and the storage battery and connected in parallel to the DC bus.

The excitation current controller has two working modes, one is grid-connected working mode, and the other is independent load running mode.

The model of the driver is HCPL-316J, the model of the exciting current controller is TMS320F2812, and the model of the charging and discharging controller is CM6048.

The model of the rotary encoder is E6A2-CW3C, the model of the stator voltage detector is JD194-BS4U3T, the model of the rotor current detector is JLKA-8ACDC 300A/4-20ma, and the model of the DC voltage detector is HT7050A-1.

Because the utility model adopts the above-mentioned structural design, the excitation circuit of the doubly-fed wind power generator is independent from the power grid, and the generator is completely provided with the excitation current by the storage battery during operation, thus getting rid of the dependence on the power grid, so the generator is not charged in the power grid It can also be started under certain circumstances, and it can also run alone with load. At the same time, the stator-side converter of the traditional doubly-fed wind power generator is omitted, so that the structure and control become simple, and the cost is saved at the same time.

Description of drawings

Fig. 1 is the structural representation of the utility model;

Figure 2 is a slip diagram of a doubly-fed asynchronous wind turbine;

Figure 3 is a stator active power diagram of a doubly-fed asynchronous wind turbine;

Figure 4 is a stator reactive power diagram of a doubly-fed asynchronous wind turbine;

Fig. 5 is a rotor current diagram of a doubly-fed asynchronous wind generator;

Figure 6 Battery power diagram.

In the figure: wind turbine 1, double-fed asynchronous wind generator 2, power grid 3, rotor-side converter 4, driver 5, excitation current controller 6, DC side buffer capacitor 7, charge and discharge controller 8, battery pack 9, A rotor encoder 10 , a stator voltage detector 11 , a rotor current detector 12 , a DC voltage detector 13 , and a gear box 14 .

Detailed ways

As shown in Figure 1, an excitation device for a doubly-fed wind power generating set includes a doubly-fed asynchronous wind power generator 2, a rotor-side converter 4, a driver 5, an excitation current controller 6, a DC-side buffer capacitor 7, and a battery pack 9. The AC terminal of the rotor-side converter 4 is connected to the rotor winding of the doubly-fed asynchronous wind generator 2, the DC terminal of the rotor-side converter 4 is connected to the battery pack 9, and the rotor-side converter 4 is also connected to the driver 5 , the driver 5 is connected with an excitation current controller 6, a DC-side buffer capacitor 7 is provided between the rotor-side converter 4 and the battery 9 and connected in parallel to the DC bus, and the stator winding of the doubly-fed asynchronous wind power generator 2 is connected to the power grid 3, The wind turbine 1 is connected to the rotating shaft of the doubly-fed asynchronous wind generator 2 through a gearbox 14 .

A charging and discharging controller 8 is also provided between the storage battery 9 and the DC side buffer capacitor 7 .

A rotary encoder 10 is provided between the doubly-fed asynchronous wind generator 2 and the gearbox 14, a stator voltage detector 11 is provided between the doubly-fed asynchronous wind generator 2 and the grid 3, and a doubly-fed asynchronous wind generator 2 and A rotor current detector 12 is provided between the rotor-side converter 4 , and a DC voltage detector 13 is provided between the rotor-side converter 4 and the battery 9 and connected in parallel to the DC bus.

The model of the driver 5 is HCPL-316J, the model of the exciting current controller 6 is TMS320F2812, and the model of the charging and discharging controller 8 is CM6048.

The model of the rotary encoder 10 is E6A2-CW3C, the model of the stator voltage detector 11 is JD194-BS4U3T, the model of the rotor current detector 12 is JLKA-8ACDC 300A/4-20ma, and the model of the DC voltage detector 13 is HT7050A-1.

The storage battery pack 9 provides excitation power for the rotor circuit of the doubly-fed asynchronous wind power generator. According to the electrical quantity fed back by the above detection devices and the operating speed of the generator, the excitation current controller 6 controls the switching of the rotor-side converter 4 through the drive circuit 5. It can adjust the amplitude, phase and frequency of the rotor excitation current, so as to realize the variable-speed and constant-frequency operation of the doubly-fed asynchronous wind turbine.

Since the rotor circuit is independently closed, the slip power required by the rotor during the operation of the double-fed asynchronous wind generator is completely provided or absorbed by the battery pack 9, so it should have sufficient capacity to ensure that the generator can last for a long time work. In order to prevent the battery pack from overcurrent during operation, a charging and discharging controller 8 is connected in the present invention, which can limit the charging or discharging current, so that the battery can work safely. In addition to removing the grid-side converter and adding battery packs and charge-discharge controllers, the other modules of the system follow the technical methods of traditional doubly-fed asynchronous wind turbines.

The excitation current controller 6 has two working modes, one is grid-connected working mode, and the other is independent load running mode. In the grid-connected operation mode, it adjusts the excitation current to complete the grid-connected control, and adjusts the active output of the generator at any time to achieve maximum power tracking. In the independent load operation mode, it controls the excitation current to make the stator generate qualified electric energy, and at the same time adjusts the output power to balance the electric energy generated by the generator and the electric energy consumed by the load.

The doubly-fed asynchronous wind turbine 2 has a wide range of speed operation. The generator will adjust the speed according to the current wind speed and operation needs. The generator will run in two different states of sub-synchronous and super-synchronous. The direction of power flow is different. When the wind speed is lower than the synchronous speed, the doubly-fed asynchronous wind turbine 2 is in the sub-synchronous operation state, and the generator excitation system needs to absorb the slip power from the battery pack 9. At this time, the rotor-side converter 4 is running in the inverter state. The accumulator pack is in a discharge state at 9 . If the electric energy of battery pack 9 is about to run out at this time, excitation current controller 6 controls the output of reducing active power, improves the rotating speed of doubly-fed asynchronous wind-driven generator 2, makes it run in super-synchronous state, to charge battery pack 9 .

When the wind speed is higher than the synchronous speed, the doubly-fed asynchronous wind turbine 2 is in a super-synchronous state, and the doubly-fed wind turbine excitation system needs to feed back slip power to the grid 3. At this time, the rotor-side converter 4 is running in the rectification state, and the battery pack 9 is charging. If the storage battery pack 9 will be fully charged at this time, the exciting current controller 4 should control to reduce the generator speed to make it run in a sub-synchronous state, thereby discharging the storage battery pack 9 .

The simulation model is built in the Matlab\Simulin environment. The parameters of the double-fed asynchronous wind turbine 2 are set as follows: rated power 10KW; rated voltage 380V; stator leakage inductance 0.005974p.u; stator loop resistance 1.115p.u; Resistance 0.01p.u; mutual inductance of stator and rotor 0.2037p.u; number of pole pairs 2; grid line voltage 380V.

As shown in Figure 2, it is the slip curve of the doubly-fed asynchronous wind turbine 2. The output reference active power of the doubly-fed asynchronous wind turbine 2 is set to be 8KW, and the reactive power is 1KVar, and the rotor circuit is observed at different speeds. Under the electric energy flow condition.

As shown in Figure 3, the active power of the double-fed asynchronous wind generator is accurately controlled at 8KW.

As shown in Figure 4, the reactive power of the double-fed asynchronous wind generator is accurately controlled at 1KVar.

As shown in Figure 5, the frequency of the current image of the rotor of the doubly-fed asynchronous wind turbine 2 changes with the change of the slip.

As shown in Figure 6, under the sub-synchronous state, that is, when the slip ratio s>0, the slip power flows from the battery pack 9 to the rotor of the doubly-fed asynchronous wind turbine 2, and the battery pack 9 is in the discharge state; under the super-synchronous state That is, when the slip ratio s<0, the slip power flows from the rotor of the doubly-fed asynchronous wind power generator 2 to the storage battery pack 9, and the storage battery pack 9 is in a charging state.

Claims (6)

1. the excitation unit of a double-fed wind power generator group, comprise dual-feed asynchronous wind power generator (2), rotor-side converter (4), driver (5), field current controller (6), DC side buffer capacitor (7), batteries (9), it is characterized in that: the interchange end of rotor-side converter (4) is connected with the rotor windings of dual-feed asynchronous wind power generator (2), the DC terminal of rotor-side converter (4) is connected with batteries (9), rotor-side converter (4) is also connected with driver (5), driver (5) is connected with field current controller (6), being provided with DC side buffer capacitor (7) between rotor-side converter (4) and storage battery (9) is parallel on DC bus, the stator winding of dual-feed asynchronous wind power generator (2) is connected with electrical network (3), wind energy conversion system (1) is connected by the rotating shaft of gear box (14) with dual-feed asynchronous wind power generator (2).

2. the excitation unit of a kind of double-fed wind power generator group according to claim 1, is characterized in that: be also provided with charging-discharging controller (8) between described storage battery (9) and DC side buffer capacitor (7).

3. the excitation unit of a kind of double-fed wind power generator group according to claim 1, it is characterized in that: between described dual-feed asynchronous wind power generator (2) and gear box (14), be provided with rotary encoder (10), stator voltage detector (11) is provided with between dual-feed asynchronous wind power generator (2) and electrical network (3), be provided with rotor current detector (12) between dual-feed asynchronous wind power generator (2) and rotor-side converter (4), be also provided with DC voltage detector (13) between rotor-side converter (4) and storage battery (9) and be parallel on DC bus.

4. the excitation unit of a kind of double-fed wind power generator group according to claim 1, it is characterized in that: described field current controller (6) has two kinds of mode of operations, one is grid-connected mode of operation, one is free band load running pattern.

5. the excitation unit of a kind of double-fed wind power generator group according to claim 1, it is characterized in that: the model of described driver (5) is HCPL-316J, the model of field current controller (6) is TMS320F2812, and the model of charging-discharging controller (8) is CM6048.

6. the excitation unit of a kind of double-fed wind power generator group according to claim 3, it is characterized in that: the model of described rotary encoder (10) is E6A2-CW3C, the model of stator voltage detector (11) is JD194-BS4U3T, the model of rotor current detector (12) is JLKA-8ACDC 300A/4-20ma, and the model of DC voltage detector (13) is HT7050A-1.