KR20170112059A - Apparatus and method for controlling switching module - Google Patents

Abstract

The present invention relates to a converter control apparatus and method for a wind power generation system, and more particularly, to a technique for maximizing the lifetime of a converter by making each of a plurality of parallel-connected converters included in a wind power generation system have the same drive time.
One problem to be solved by the proposed invention is to drive a plurality of converters connected in parallel from a converter having a small cumulative drive time so as to equalize the drive times of the plurality of converters and thereby to prevent the life of the specific converter from being shortened .
According to an aspect of the present invention, a converter control apparatus of a wind power generation system may be configured to drive a converter having the smallest cumulative drive time when driving any one of a plurality of converters connected in parallel between a generator and a system, And a converter driving unit for driving a converter of the next sequential number of the last driven converter based on the driving order.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and a method for controlling a switching element of a wind turbine,

The present invention relates to an apparatus and method for controlling a switching device module of a wind power generation system, and more particularly, to a technique for minimizing a harmonic component included in an alternating current generated by a converter by varying a driving timing of a plurality of switching device modules included in the converter.

Wind turbines convert the kinetic energy of the wind into mechanical energy by rotating the blades. The converted mechanical energy is converted into electric energy through the generator.

The converter existing between the generator and the grid of the wind turbine included only one switching device module. When the wind is blowing, the blades of the wind turbine system are rotated, and the kinetic energy resulting from the rotation of the blades is converted into electrical energy through the generator. The electric energy generated and converted by the generator is converted into direct current by the switching element module included in the above-mentioned converter by the alternating current power, and is converted into alternating current to be supplied in the direction of the system again.

According to the above-described procedure, when the wind blows, only one switching element module included in the converter must be driven.

In this case, when the switching element module driven by the pulse width control method is off, the current decreases, but when the inductance of the inductor of the filter connected to the output terminal of the converter is large, the current gradually decreases. Using inductors with large inductances to slowly reduce the current leads to uneven size and cost of the filter.

One of the problems to be solved by the proposed invention is to include a plurality of switching element modules connected in parallel between a generator and a system of a wind power generation system so that a plurality of switching element modules are driven so as to have a phase difference, To reduce the harmonic component to the alternating current.

Another problem to be solved by the proposed invention is that a converter connected between a generator and a system of a wind power generation system includes a plurality of switching element modules connected in parallel and drives the plurality of switching element modules with a predetermined phase difference, The harmonic component is reduced by the alternating current outputted by the inverter.

Another problem to be solved by the proposed invention is to include a plurality of switching element modules connected in parallel between a generator and a system of a wind power generation system, wherein a plurality of switching element modules are included in one converter at 360 degrees And a plurality of switching elements connected in parallel to each other, so that the harmonic components are reduced by the alternating current outputted by the converter.

According to an aspect of the present invention, a switching device module control device of a wind power generation system includes: a plurality of switching device modules connected in parallel between a generator and a system, the plurality of switching device modules being turned on and off, And a switching element module driving unit.

In another aspect, the phase difference may be a constant phase difference.

In still another aspect, the switching device module control device of the wind power generation system further includes a phase difference calculation unit for calculating a phase difference by dividing the number of parallel-connected switching device modules included in one converter by 360 degrees And the switching device module driving unit drives the plurality of switching device modules so that the calculated phase difference is equal.

In another aspect, a switching device module control apparatus of a wind turbine system further includes at least one converter including at least one switching device module, wherein the at least one switching device module is an AC / DC A DC / AC inverter including a converter, a DC link connected in parallel with the AC / DC converter, and six switching elements and connected in parallel with the DC link.

The proposed invention includes a plurality of switching device modules connected in parallel between a generator and a system of a wind power generation system. The plurality of switching device modules are driven so as to have a phase difference so that a harmonic component .

The proposed invention includes a plurality of switching element modules connected in parallel between a generator and a system of a wind power generation system. The plurality of switching element modules are driven so as to have a predetermined phase difference so that a harmonic component Can be reduced.

The proposed invention includes a plurality of switching device modules connected in parallel between a generator and a system of a wind power generation system, wherein a plurality of switching device modules are connected to a plurality of switching device modules So that the harmonic component can be reduced by the alternating current outputted by the converter.

Figure 1 shows the overall configuration of a wind power generation system.
2 shows a configuration of a switching element module according to an embodiment.
3 shows a configuration of a converter control apparatus of a wind power generation system according to an embodiment.
FIG. 4 shows a current waveform of any one of the three phases outputted by the converter according to the switching element module driven according to the conventional method.
5 shows a current waveform of any one of the three phases outputted by the converter according to the switching element module driven by the switching element module control apparatus of the wind power generation system.
6 shows a flow of a converter control method of a wind power generation system according to an embodiment.

The foregoing and further aspects are embodied through the embodiments described with reference to the accompanying drawings. It is to be understood that the components of each embodiment are capable of various combinations within an embodiment as long as no other mention or mutual contradiction exists. Furthermore, the proposed invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly illustrate the claimed invention, parts not related to the description are omitted, and like reference numerals are used for like parts throughout the specification. And, when a section is referred to as "including " an element, it does not exclude other elements unless specifically stated to the contrary.

In addition, throughout the specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected", but also an "electrically connected" . Further, in the specification, a signal means a quantity of electricity such as a voltage or a current.

As used herein, the term " block " refers to a block of hardware or software configured to be changed or pluggable, i.e., a unit or block that performs a specific function in hardware or software.

Figure 1 shows the overall configuration of a wind power generation system.

The wind power generation system includes a blade 10, a gear box, a generator 40, a plurality of converters 50-1, 50-2 and 50-n, a transformer 70 and a converter control device 100 of a wind power generation system .

In one embodiment, the blades 10 are rotated by wind energy to generate kinetic energy. That is, the blade 10 is a machine that converts the energy of a fluid such as water, gas, or steam into mechanical work. The blades 10 may be embodied in a vertical or horizontal orientation with the ground and include one or more blades.

In one embodiment, the gear box 30 is located between the blades 10 and the rotor of the generator 40 described below. The gear box 30 has a low wind speed and functions to increase the rotational speed of the rotor of the generator 40 when the rotational speed of the blade 10 is low.

In one embodiment, the energy generated by the fluid is converted into rotational force by the rotor, and then the rotational force is used to generate electricity. That is, the generator 40 is a device that converts mechanical energy into electrical energy. As the generator 40, a synchronous machine or an induction machine is largely used, and the synchronous machine can be divided into a winding machine type and a permanent magnet type according to the form of the field. The induction machine can be classified into a spiral type and a winding type according to the structure of the rotor. In particular, the wire-wound induction machine, the wire-wound induction generator 40 or the induction generator 40 can be installed in a place characterized by a variable wind speed.

In one embodiment, converters 50-1, 50-2, and 50-n include a DC link connecting an AC / DC converter, a DC / AC inverter, and an AC / DC converter and a DC / AC inverter. The converters 50-1, 50-2 and 50-n are connected in parallel between the generator 40 and a transformer 70 to be described later. Figure 1 shows n parallel connected converters 50-1, 50-2, 50-n.

The AC / DC converter converts the three-phase AC output from the generator 40 into a DC form. The DC / AC inverter converts the converted DC power into AC power suitable for use on the grid side. DC links can be connected in parallel to AC / DC converters and DC / AC inverters to transfer energy between AC / DC converters and DC / AC inverters. The DC link can be implemented as a capacitor, but any device capable of charging and discharging energy can be used as a DC link. 1 illustrates a plurality of converters connected in parallel, but not limited thereto, only one converter may be present.

In one embodiment, converters 50-1, 50-2, and 50-n include one or more switching element modules 60-1-1, 60-1-2, 60-1-m, 60-2-1 , 60-2-2, 60-2-m, 60-n-1, 60-n-2, 60-nm. 1 is a block diagram showing a configuration of m parallel-connected switching elements 60-1-1, 60-1-2, 60-1-m and 60-2-m including the converters 50-1, 50-2 and 50- 1, 60-2-2, 60-2-m, 60-n-1, 60-n-2, 60-nm. The above-mentioned AC / DC converter includes six switching elements, and the DC / AC inverter also includes six switching elements. The above-mentioned switching elements may be transistors, for example, gate turnoff thyristors (GTO), insulated gate bipolar transistors (IGBTs), integrated gate commutated thyristors (IGCTs), bipolar junction transistors Oxide Semiconductor Field Effect Transistor).

The AC power output from the generator 40 is three-phase AC power. Each phase is connected to two switching elements of the AC / DC converter. Each phase of the three-phase AC power supplied to the system includes two switching Lt; / RTI > That is, two of the six switching elements of the AC / DC converter operate so that current can flow in one phase. Two of the six switching devices of the DC / AC inverter operate so that current can flow through one phase.

In one embodiment, the switching element modules 60-1-1, 60-1-2, 60-1-m, 60-2-1, 60-2-2, 60-2-m, 60- 1, 60-n-2, 60-nm) includes six switching elements of an AC / DC converter and six switching elements of a DC / AC inverter and a DC link. The switching element modules 60-1-1, 60-1-2, 60-1-m, 60-2-1, 60-2-2, 60-2-m, 60- 2, and 60-nm are connected in parallel to constitute one converter 50-1, 50-2, and 50-n.

In one embodiment, the transformer 70 is connected to the grid as a portion that changes the value of the AC voltage or current using electromagnetic induction. Here, the system means a power system in which the wind power generation system is connected.

2 shows a configuration of the switching element module 200 according to one embodiment. The switching element modules 60-1-1, 60-1-2, 60-1-m, 60-2-1, 60-2-2, 60-2-m, 60- , 60-n-2, and 60-nm are the same as the detailed configuration of the switching element module 200 shown in FIG. The switching element module 200 includes six switching elements of the AC / DC converter 210 and six switching elements of the DC / AC inverter 230 and the DC link 220. The AC / DC converter 210 converts the AC output from the generator into a DC form. The DC / AC inverter 230 converts the converted direct-current power into an alternating-current form and transfers it to the system side. The configuration for converting AC power into DC power, and the configuration for converting DC power to AC power are obvious to those skilled in the art.

Power supplied to the system is three-phase alternating-current power. In the case of one of the three phases, two of the six switching elements of the AC / DC converter 210 must be turned on in order for AC power to be transmitted to the system And two of the six switching elements of the DC / AC inverter 230 should be turned on. These features are apparent to those of ordinary skill in the art of converters.

3 shows a configuration of a converter control apparatus 100 of a wind power generation system according to an embodiment.

In an aspect, the switching element module control apparatus 100 of the wind power generation system includes a switching element module driving unit 110. [

In one embodiment, the switching device module driving unit 110 turns on and off a plurality of switching device modules connected in parallel including a converter connected between the generator and the system, and drives the plurality of switching device modules with a phase difference. 1, for example, the switching element module driving unit 110 includes m switching element modules 60-1-1, 60-1-2, ... 60-1-m, and drives them so as to produce a phase difference. It has been described that four switch elements must be turned on in order to supply AC power to the system based on any one of the phases. As a result, when any one of the phases is taken as an example, the four switching elements included in each of the switching element modules 60-1-1, 60-1-2, ..., 60-1-m have a phase difference And simultaneously turned on and off. A series of processes in which the four switch elements included in any one of the switching element modules are turned on and have a constant phase difference and the four switch elements included in the next switching element module are turned on are generated for the m switching element modules.

The switching device module driving unit 110 turns on and off a plurality of parallel-connected switching device modules included in the converter. That is, in order for the three-phase AC signals to be transmitted to the system such that the three- The switch element is turned on and off. What is required among the twelve switching elements included in the switching element module to be transmitted to the system so that the three-phase alternating signals are different from each other by 120 degrees and what kind of switching element should be turned on and off is a common knowledge in the field of converters Be clear to those who have.

For example, when the switching element module driving unit 110 turns on / off a plurality of parallel-connected switching element modules included in the converter, the four switching elements included in the switching element module are turned on / off .

For example, the switching device module driving unit 110 turns on and off necessary switching devices among a plurality of switching devices included in the switching device module so that the three-phase AC power is supplied to the system. The above-described necessary switch elements eventually have a phase difference for each switching element module and are turned on and off.

In one embodiment, the phase difference is a constant phase difference. The switching element module driving unit 110 turns on and off a plurality of switching element modules connected in parallel including a converter connected between the generator and the system, and drives the plurality of switching element modules with a phase difference.

For example, the switching element module driving unit 110 turns on and off the four switching elements included in each of the plurality of parallel-connected switching element modules included in the converter, Is turned on and off with a certain phase difference. The definition of turning on and off a plurality of switching element modules has been described above. The fact that a constant phase difference occurs means that the plurality of switching element modules are simultaneously turned on and off so as to have a constant phase difference therebetween. It does not mean that a certain phase difference is controlled between the switch elements included in the switching element module.

In one embodiment, the switching device module control apparatus 100 of the power generation system further includes a phase difference calculating section 120. [

In one embodiment, the phase difference calculator 120 calculates a phase difference by dividing the number of parallel-connected switching element modules included in one converter by 360 degrees, and the switching element module driving unit 110 calculates And the plurality of switching element modules are driven so as to produce a calculated phase difference.

Taking the converter 50-1 of Fig. 1 as an example, the converter 50-1 includes m switching element modules, and m is assumed to be four. The phase difference calculating unit 120 calculates the phase difference by 90 degrees by dividing the number of the switching element modules by 4 at 360 degrees. The switching element module drives the four switching element modules included in the converter 50-1 so that the calculated phase difference is 90 degrees. The other converters 50-2, ..., 50-n also operate in the same manner as the converter 50-1. Conventionally, a plurality of switching element modules included in the converter 50-1 are driven so as to be simultaneously turned on and off. Accordingly, a large amount of harmonic components were contained in the alternating current outputted from the converter. However, the switching device module driving unit 110 included in the switching device module control device 100 of the wind power system turns on and off the switching device module so that a phase difference is obtained by dividing the number of the switching device modules by 360, There is less harmonic component in AC power.

In one embodiment, the switching device module control apparatus of the wind power generation system further includes at least one converter including at least one switching device module, wherein the at least one switching device module includes an AC / DC converter, a DC link connected in parallel with the AC / DC converter, and a DC / AC inverter including six switching elements and connected in parallel with the DC link. Referring to Fig. 1, a switching device module control apparatus of a wind power generation system includes one or more converters 50-1, 50-2, ..., 50-n. Each converter includes one or more switching element modules 60-1-1, 60-1-2, 60-1-m, 60-2-1, 60-2-2, 60-2-m, 60-n- 1, 60-n-2, 60-nm).

Referring to FIG. 2, each switching element module 200 includes an AC / DC converter 210 including six switching elements, a DC / AC inverter 230 including six switching elements, and a DC link . The AC / DC converter 210, the DC / AC inverter 230 and the DC link are connected in parallel with each other.

FIG. 4 shows a current waveform of any one of the three phases outputted by the converter according to the switching element module driven according to the conventional method. The square wave shown in Fig. 4 is a voltage waveform of the system. When the switching device module is turned on, the voltage waveform becomes maximum, which is the same as the voltage of the DC link. The current waveform is the waveform that follows the solid line with increasing or decreasing voltage waveforms. The output current of the converter rapidly decreases when a plurality of switching element modules included in any one of the converters are simultaneously turned on and off, and the output current increases sharply when the switching element module is turned on at the same time. As a result, a current containing a large amount of harmonics is transmitted to the system.

5 shows a current waveform of any one of the three phases outputted by the converter according to the switching element module driven by the switching element module control apparatus of the wind power generation system. Since a plurality of switching element modules included in any one of the converters operates with a constant phase difference, the number of switching elements is reduced when all of the switching element modules are turned on and off at the same time. There is hardly occurred when all of the switching element modules are turned off during the 180-degree phase interval shown in FIG. 5, so that there is no period in which the current magnitude itself falls sharply.

5 shows the current waveform output by the converter for one phase under the assumption that the converter includes three switch element modules. First, the solid line is the switching element module that is first turned on, the dotted line is the switching element module that is turned on next, and the one-dot chain line is the switching element module that is turned on the third time. The three switching element modules described above are driven with a constant phase difference.

6 shows a flow of a converter control method of a wind power generation system according to an embodiment.

In an aspect, a method of controlling a switching element module of a wind power generation system includes a step of driving a switching element module (S620).

In an exemplary embodiment, the step of driving the switching element module S620 may turn on and off a plurality of parallel-connected switching element modules included in a converter connected between the generator and the system, and drives the plurality of switching element modules to have a phase difference . For example, in the converter 50-1 shown in FIG. 1, the step of driving the switching element module S620 includes m switching element modules 60-1-1 and 60-1-2 included in the converter 50-1 , ... 60-1-m), and drives them so as to produce a phase difference. It has been described that four switch elements must be turned on in order to supply AC power to the system based on any one of the phases. As a result, when any one of the phases is taken as an example, the four switching elements included in each of the switching element modules 60-1-1, 60-1-2, ..., 60-1-m have a phase difference And simultaneously turned on and off. A series of processes in which the four switch elements included in any one of the switching element modules are turned on and have a constant phase difference and the four switch elements included in the next switching element module are turned on are generated for the m switching element modules.

The step S620 of driving the switching element module turns on / off a plurality of parallel-connected switching element modules included in the converter means that the three-phase AC signals are transmitted to the system such that the three- And turning on and off the necessary switch elements among the elements. It is obvious to those skilled in the art which switching element among the twelve switching elements included in the switching element module to be transmitted to the system so that the three-phase AC signals are different from each other by 120 degrees and when the switching element should be on and off. For example, when the switching element module driving step S620 turns on / off a plurality of parallel-connected switching element modules included in the converter, it means that four switching elements included in the switching element module are turned on Off.

Taking the three-phase as an example, the step of driving the switching element module (S620) turns on and off necessary switching elements among the plurality of switching elements included in the switching element module so that the three-phase AC power is supplied to the system. The above-described necessary switch elements eventually have a phase difference for each switching element module and are turned on and off.

In one embodiment, the phase difference is a constant phase difference. The step S620 of driving the switching device module turns on and off a plurality of switching device modules connected in parallel, which are connected to each other between a generator and a system, and drives the plurality of switching device modules so as to generate a phase difference.

For example, the step of driving the switching element module (S620) turns on / off the four switching elements included in each of the plurality of parallel-connected switching element modules included in the converter, The module is turned on and off with a constant phase difference. The definition of turning on and off a plurality of switching element modules has been described above. The fact that a constant phase difference occurs means that the plurality of switching element modules are simultaneously turned on and off so as to have a constant phase difference therebetween. It does not mean that a certain phase difference is controlled between the switch elements included in the switching element module.

In one embodiment, the switching element module control method of the power generation system further includes a phase difference calculation step (S610).

In one embodiment, the phase difference calculation step S610 calculates the phase difference by dividing the number of parallel-connected switching element modules included in one converter by 360 degrees, Is characterized in that the plurality of switching element modules are driven so that the calculated phase difference becomes equal.

Taking the converter 50-1 of Fig. 1 as an example, the converter 50-1 includes m switching element modules, and m is assumed to be four. The phase difference calculation step S610 calculates the phase difference by 90 degrees by dividing the number of the switching element modules by 4 at 360 degrees. The switching element module drives the four switching element modules included in the converter 50-1 so that the calculated phase difference is 90 degrees. The other converters 50-2, ..., 50-n also operate in the same manner as the converter 50-1. Conventionally, a plurality of switching element modules included in the converter 50-1 are driven so as to be simultaneously turned on and off. Accordingly, a large amount of harmonic components were contained in the alternating current outputted from the converter. However, in the switching device module driving step (S620) included in the switching device module control method of the wind power generation system, the switching device module is turned on and off so that the phase difference is obtained by dividing the number of the switching device modules by 360, There is less harmonic content in power.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation and that those skilled in the art will recognize that various modifications and equivalent arrangements may be made therein. It will be possible. Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.

10: Blade
30: Gearbox
40: generator
50-1, 50-2, 50-n: converter
60-1-1, 60-1-2, 60-1-m, 60-2-1, 60-2-2, 60-2-m, 60-n-1,60- nm: Switching element module
70: Transformer
100: Switching element module control device of wind power generation system
110: Switching element module driving part
120: Phase difference calculating section
210: AC / DC converter
220: DC link
230: DC / AC Converter
200: Switching element module

Claims (7)

And a switching element module driving unit for turning on and off a plurality of switching element modules connected in parallel and including a converter connected between the generator and the system so as to drive the plurality of switching element modules with a phase difference, controller.
2. The method of claim 1,
A device for controlling a switching device module of a wind power system having a constant phase difference.
2. The wind turbine of claim 1, wherein the switching device module control device of the wind power generation system
And a phase difference calculator for calculating a phase difference by dividing the number of parallel-connected switching element modules included in one converter by 360 degrees,
Wherein the switching device module driving unit drives the plurality of switching device modules such that the calculated phase difference is increased.
The apparatus of claim 1, wherein the switching device module control device of the wind power generation system
One or more converters comprising one or more switching element modules,
Wherein the at least one switching element module includes an AC / DC converter including six switching elements, a DC / AC inverter including a DC link and six switching elements connected in parallel with the AC / DC converter and connected in parallel with the DC link Switching element module control device of wind power system.
And a switching element module driving step of turning on and off a plurality of switching element modules connected in parallel and including a converter connected between the generator and the system so as to drive the plurality of switching element modules with a phase difference, Module control method.
6. The method of claim 5,
A method of controlling a switching element module of a wind power system having a constant phase difference.
6. The method according to claim 5, wherein the switching element module control method of the wind power generation system
And a phase difference calculating step of calculating a phase difference by dividing the number of parallel-connected switching element modules included in one converter by 360 degrees,
Wherein the step of driving the switching device module drives the plurality of switching device modules such that the calculated phase difference is equal to or greater than a predetermined value.

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