KR101586824B1 - wind power generating system for enhancing power efficiency - Google Patents

Abstract

The present invention can dramatically reduce the installation and maintenance cost by transmitting the maximum power to generated power without installing an expensive wind speed sensor, and it can reduce the maximum current command value The maximum power can be transmitted to the load and the system without complicated computation. The blade control unit checks whether the generated power is '0' every predetermined period (T2). If the generated power is '0' The present invention provides a wind power generation system capable of remarkably increasing the power efficiency by allowing the blades to be rotated easily even at a weak wind speed by supplying the start power, which is the minimum voltage required for the initial rotation of the blades, to the blade driving unit for a predetermined set time (TH) .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a wind power generating system,

The present invention relates to a wind power generation system, and more particularly, to a wind power generation system that maximizes power generated by a blade through maximun power point tracker control without installing an expensive wind speed sensor for detecting wind speed, The present invention relates to a wind power generation system capable of dramatically increasing power efficiency by smoothly rotating a blade even at a weak wind speed.

The wind power generation system is a power generation system for converting natural energy into electric energy. It is attracting attention as a clean energy source that does not emit pollutants in the energy acquisition stage.

Generally, in a wind power generation system, the amount of electric power generated by the rotation of the blades is transferred to a system or a load in accordance with the control of the power conversion apparatus, and the amount of electric power transmitted to the system or the load differs depending on the rotation rate of the blades. The rotation rate is defined as the rotation speed of the blade at the same wind speed.

The conventional wind power generation system includes a wind speed sensor such as an expensive encoder and a hall sensor for detecting the wind speed and a generator speed detection unit for detecting the speed of the generator. The speed detected by the generator speed detection unit is used as a wind power generator And the calculated current command value is transmitted to the DC-DC booster converter so that the maximum power is transmitted to the load and the system.

As described above, the conventional wind power generation system has a disadvantage that installation and maintenance costs increase because an expensive wind speed sensor must be provided in order to transmit maximum power from the power generated by the blade to the system.

In order to solve these problems, various researches have been conducted on a wind power generation system or a power conversion system for delivering maximum power to a boiler or a system without an expensive wind speed sensor.

1 is a block diagram showing a generator system disclosed in Korean Patent No. 10-1093314 (entitled: Generator System and Generation Method).

The generator system 100 of FIG. 1 includes a blade 110 that converts the force of the wind into a rotational force, a permanent magnet synchronizer 120 that converts the rotational force of the blade 110 into electric energy, A generator side converter 130 for converting the AC power generated by the permanent magnet synchronous machine 120 into DC power, a power storage unit 140 for storing the converted DC power, a converter 130 for converting the accumulated DC power into an AC Side converter 150, a filter 172 for suppressing the ripple current at the system-side output terminal, a system-link opening / closing device (SW) 174 for opening and closing the generator and the system, a generator-side converter 130, And a controller 160 for controlling the operation of the controller 150.

In the conventional art 100 configured as described above, the control unit 160 is configured to analyze the pattern of the generated electric current to determine the phase angle of the permanent magnet synchronous machine 120, so that it is possible to perform the power generating operation according to the wind speed without installing a separate wind speed sensor It becomes possible to control.

However, in the conventional art 100, when the control unit 160 determines the rotation phase angle of the field from the pattern in which the ripple currents of the three output lines of the three phases appear alternately during the time when the field of the permanent magnet synchronous machine 120 makes one revolution Since this method is driven by the detection method, there is a limitation that it can not detect an accurate phase angle, and this limit lowers the power efficiency because the maximum power for the wind speed can not be transmitted to the system or to the system.

The blade also has the following characteristics. 1) If the wind speed is equal to or greater than the first limit value, the rotation is smoothly performed. If the wind speed is less than the threshold value, the rotation is not performed. 2 When the wind speed exceeds the limit value, rotation is continuously performed. In this case, the first limit value is defined as a minimum wind speed value required for rotation when the blade is stopped, and the second limit value is defined as a minimum wind speed value required for the rotation to be continuously performed in a state where the blade rotates, 1 threshold is greater than the second threshold.

That is, the conventional technology 100 has a limitation that the rotation of the blades is not performed in an environment where the wind speed is less than the first threshold value, and the power efficiency is significantly lowered.

In this way, it is possible to transmit 1) the maximum power to the wind speed without using an expensive wind speed sensor, 2) to increase the power efficiency by inducing the rotation of the blade at the wind speed less than the first limit value, Is the urgent need of research.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a wind power generator which can remarkably reduce installation and maintenance costs by transmitting maximum power to generated power without installing an expensive wind speed sensor To provide a wind power generation system.

Another object of the present invention is to provide a wind power generation system capable of transmitting a maximum power to a wind turbine and a grid without complicated operation because a maximum current command value is detected by utilizing a preset maximum power detection table.

Further, another problem to be solved by the present invention is that the blade control unit checks whether the generated power is '0' every predetermined period (T2), and if the generated power is '0', the minimum voltage The present invention is to provide a wind power generation system capable of remarkably increasing power efficiency by allowing the blade to be rotated easily even at a weak wind speed by supplying power to the blade driving unit during a predetermined set time (TH).

According to an aspect of the present invention, there is provided a method of controlling an electric power generating apparatus including a generator that converts a rotational force of a blade into electric energy, a first detecting unit that detects a generated power that is a power value of the generator, A power conversion unit comprising a main control unit for determining a maximum current command value; A power storage unit that charges surplus power of the machining power that is the power controlled by the main control unit; A blade driving unit for driving the blade when power is supplied thereto; A first comparison module for comparing whether the generated power detected by the first detection unit is '0'; and a second comparison module for driving the blades when the generated power is '0' And a control module for controlling the first comparing module so that the generated power is '0' so that the stored power of the power storage unit is switched to the start Wherein the control module of the blade control unit controls the second comparison module to determine whether the power storage power is equal to or greater than the start power for a predetermined set time TH1 When the starting power is supplied to the blade driving unit and the storage power is less than the starting power by the second comparison module, The load supply is controlled so that the storage electric power is not supplied.

Also, in the present invention, the power converter includes a three-phase rectifier for converting the three-phase alternating current generated by the generator into three-phase direct current; A DC-DC boost converter for keeping the three-phase DC converted by the three-phase rectifier constant in correspondence with the maximum current command value detected by the main controller; A three-phase inverter for converting the direct current maintained in the DC-DC boost converter into three-phase alternating current; And a second detection unit for detecting an output current and a voltage of the DC-DC boost converter, wherein the main control unit controls the three-phase inverter with the voltage and current detected from the second detection unit, It is preferable that the generation voltage and the current are detected from the first detector, and if the detected generation voltage is equal to or greater than a predetermined minimum voltage, the generated power is transmitted to the first or second system.

Further, in the present invention, when the generated voltage is equal to or greater than the minimum voltage, the main controller calculates a maximum current command value corresponding to the generated voltage and current using the maximum power detection table stored with the line voltage, the line- And if the current power is less than the previous power, decreasing the maximum current command value and decreasing the maximum current command value when the current power is less than the previous power, It is preferable that the current command value is pulse-width-modulated by the proportional-plus-integral controller, and the DC-DC boost converter is controlled through the IGBT control board by the pulse-width-modulated control signal.

The blade control unit may further include a second comparison module that is driven when the generated power is '0' by the first comparison module and compares the stored power of the power storage unit with the startup power, And the control module controls the second comparison module such that the startup power is supplied to the blade driving unit when the power storage electric power is equal to or greater than the startup power.

Further, in the present invention, it is preferable that the control module controls the start power to be supplied only for a predetermined set time (TH1).

According to the present invention having the solution, the installation and maintenance cost can be reduced.

Also, according to the present invention, it is possible to increase the power efficiency by transferring the maximum power to the subsystem and the subsystem while the computation is not complicated.

Further, according to the present invention, even in an environment where the wind speed is low, the blades can easily rotate and the power efficiency can be remarkably increased.

1 is a block diagram showing a generator system disclosed in Korean Patent No. 10-1093314 (entitled: Generator System and Generation Method).
2 is a control block diagram illustrating a wind power generation system according to an embodiment of the present invention.
3 is a circuit diagram of the power conversion unit of FIG.
Fig. 4 is a real world view showing Fig.
FIG. 5 is a graph showing the line-to-line voltage and the load-line current according to the angular velocity of the rotor in the permanent magnet synchronous generator of FIG.
FIG. 6 is a block diagram showing the blade control unit of FIG. 2. FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a control block diagram showing a wind turbine system according to an embodiment of the present invention, FIG. 3 is a circuit diagram of the power conversion unit of FIG. 2, and FIG.

The wind power generation system 1 of Figs. 2 and 3 includes a blade 15, a blade driving unit 12, a generator 2, a three-phase rectifier 3, a first detection unit 4, a DC-DC boost converter 5 A main control unit 8, an IGBT control board 9, an IPM control board 10, and a blade control unit 13. The three-phase inverter 6, the second detection unit 7, the power storage unit 11, At this time, the generator 2, the three-phase rectifier 3, the first detecting unit 4, the DC-DC boost converter 5, the three-phase inverter 5, the three- The main control unit 8, the IGBT control board 9 and the IPM control board 10 will be referred to as a power conversion unit.

The blade 15 is a device for converting the transmitted wind force into rotational force.

The blade driving unit 12 drives the blade 15 under the control of the blade control unit 13.

The generator 2 is connected to the blade 15 and converts the rotational force of the blade 15 into electric energy.

In this case, it is preferable that the generator 2 is a permanent magnet synchronous generator (PMSG) having a high power efficiency, which can operate at a low speed by reducing the pole pitch and increasing the number of poles.

FIG. 5 is a graph showing the line-to-line voltage and the load-line current according to the angular velocity of the rotor in the permanent magnet synchronous generator of FIG.

The permanent magnet synchronous generator 2 has a linear characteristic in which the line voltage and the line-to-line current (load current) are linearly inversely proportional to each other, specifically, the voltage and the current have linear characteristics according to the rotor speed as shown in Fig.

That is, if the rotational speed (rotor speed) of the blade 15 is known, the maximum output of the generator corresponding to the speed can be calculated. If the voltage and current are known, the maximum power at the corresponding rotor speed can be deduced .

As described above, according to the present invention, it is possible to transmit the maximum power generated in the generator to the system or the load using only two parameters of the voltage and current of the generator without detecting the speed of the blade 15 by utilizing this characteristic of the permanent magnet synchronous generator 2 .

The three-phase rectifier 3 is connected to the output terminal of the generator 2 and is composed of a diode to rectify the three-phase AC power output from the generator 2 by the three-phase DC power. At this time, the three-phase rectifier 3 performs power factor correction using a known CRM technique.

The first detecting section 4 is connected to the output terminal of the three-phase rectifier 3 and detects the voltage and current of the three-phase DC power outputted from the three-phase rectifier 3 every predetermined period (T1) Current is detected.

The first detection unit 4 also inputs the detected voltage and current values to the main control unit 8. At this time, the main control unit 8 responds to the voltage and current values received from the first detection unit 4 by using the current control based on MPPT (hereinafter referred to as MPPT power control) And then inputs a control signal corresponding to the selected maximum current command value to the DC-DC boost converter 5. A method of calculating the maximum current command value by the main control unit 8 will be described in detail later in the main control unit 8.

The DC-DC boost converter 5 constantly outputs the output voltage of the three-phase rectifier 3 to the voltage of the maximum current command value input from the main controller 8. [

The DC-DC boost converter 5 is composed of a capacitor C, an IGBT switching element, and a diode.

The three-phase inverter 6 converts the three-phase DC power output from the DC-DC boost converter 5 into three-phase AC power. At this time, the three-phase inverter 6 is composed of a power control element of any one of the transistor TR, the FET, and the SCR.

The second detecting section 7 detects the voltage and current output from the three-phase inverter 6, and inputs the detected voltage and current to the main control section 8.

The power storage unit 11 stores energy by charging surplus power at the light load and discharges the surplus power that is charged when the power is insufficient.

The power storage unit 11 also supplies the starting power to the blade driving unit 12 under the control of the blade control unit 13.

The main control unit 8 detects the generated voltage and current by controlling the first detecting unit 4 every period T1 and compares the detected voltage with a predetermined minimum voltage V1 to detect the detected voltage as the minimum voltage V1 ), A maximum power point tracker control will be described with respect to the detected voltage.

The main control unit 8 also stores the maximum current detection table in advance. At this time, the maximum current detection table stores the line voltage, the line current, and the maximum current command values of the rotor angular velocity using the characteristic that the line voltage and the line-to-line current are linear as described above with reference to FIG.

The maximum power point tracker control uses a preset maximum current detection table to select a maximum current command value corresponding to the current and voltage input from the first detection unit 4, The PWM switching command value is determined by increasing the current command value when the power is increased and decreasing the current command value when the power is decreased. That is, the main controller 8 selects the maximum current command value for the power generation voltage and power higher than the predetermined minimum voltage V1 through the maximum power point tracker control.

Further, the main control unit 8 inputs the determined PWM switching command value to the IGBT main control unit 8 to control the DC-DC boost converter 5.

Further, the main control unit 8 converts the voltage and current input from the second detection unit 7 into a d-q axis coordinate system, which is a reactive power component of the three-phase coordinate system and an active power component, and performs vector control. In other words, in the initial transient state, the d-axis and q-axis command value components are applied as interference terms, and the d-axis command value of the reactive power is controlled to be a '0' component.

That is, the main control unit 8 inputs the detected PWM control signal to the IPM control board 10, converts the DC voltage into a three-phase AC voltage in the three-phase inverter 6, and transfers the maximum power to the system or the independent load .

FIG. 6 is a block diagram showing the blade control unit of FIG. 2. FIG.

The blade control unit 13 of FIG. 6 includes a control module 301, a first comparison module 303, a second comparison module 305, and a determination module 307.

The control module 301 is an operating system of the main control unit 8 and controls the controlled objects 303, 305, and 307.

In addition, the control module 301 controls the first comparison module 303 to be driven every predetermined period T2.

Also, the control module 301 controls the second comparison module 305 to operate when the generated power is '0' by the first comparison module 303.

In addition, the control module 301 controls the determination module 307 to drive when the stored power stored in the power storage unit 11 by the second comparison module 305 is equal to or greater than a predetermined start power.

The control module 301 also controls the power supply unit 11 to supply the starting power to the blade driving unit 12 during a predetermined first set time TH1 (Threshold 1) according to the value determined by the determination module 307. [ At this time, the first set time TH1 is defined as the time at which the starting power is supplied to the blade driving unit 12, and the starting power is defined as the minimum power value required for rotating the blade 15 in the unrotated state. That is, when the blade 15 is in the unrotated state, the starting power is supplied for the first set time TH1, and the blade 15 is rotated.

That is, the permanent magnet synchronous generator 2 connected to the blade 15 is provided with a magnet, a coil, and the like, and a load due to the magnetic force lines of the magnet and the coil is applied, so that a predetermined maneuvering force is required for the blade to start for the first time. At this time, the rotated blade is continuously rotated at a speed higher than the limit value. That is, the present invention can significantly increase the power efficiency by supplying the starting power in the period (T2) when the blade is not rotated.

The first comparison module 303 compares the generated power detected by the first detector 4 with '0' for every predetermined period T2 according to the control of the control module 301. If the generated power is' 0 ', the operation is stopped. If the generated power is' 0', the second comparison module 305 is driven. At this time, when the generated power is '0', it means that the blade 15 is not rotated.

The second comparison module 305 is driven when the generated power is '0' by the first comparison module 303 and compares the stored power stored in the power storage unit 11 with a predetermined start power.

Also, the second comparison module 305 stops the operation if the power storage power is less than the start power, and the first determination module 303 is driven if the power storage power is greater than the start power.

The determination module 307 is driven when the power storage electric power is greater than the starting power by the second comparison module 305 and the starting power is supplied from the power storage unit 11 to the blade driving unit 12 for the first predetermined time TH1 And the blade driving section 12 is supplied with the starting power by the control module 301.

1: Wind power generation system 2: Generator 3: Three-phase rectifier
4: first detection unit 5: DC-DC booster converter
6: 3-phase inverter 7: second detecting section 8:
9: IGBT board 10: IPM board 11: Power storage unit
12: blade driving part 13: blade control part
15: Blade

Claims (5)

And a main control section for controlling the power generated by the generator to determine a maximum current command value, wherein the generator includes a generator that converts the rotational force of the blade into electric energy, a first detection section that detects generation power as a power value of the generator, ;
A power storage unit that charges surplus power of the machining power that is the power controlled by the main control unit;
A blade driving unit for driving the blade when power is supplied thereto;
A first comparison module for comparing whether the generated power detected by the first detection unit is '0'; and a second comparison module for driving the blades when the generated power is '0' And a control module for controlling the first comparing module so that the generated power is '0' so that the stored power of the power storage unit is switched to the start And a second comparison module for comparing power abnormality with each other,
Wherein the control module of the blade control unit supplies the starting power to the blade driving unit during a predetermined set time (TH1) when the power storage electric power is equal to or greater than the starting power by the second comparison module, And controls not to supply the storage power to the blade supply unit when the storage power is less than the startup power. The power conversion apparatus according to claim 1,
A three-phase rectifier for converting the three-phase alternating current generated by the generator into three-phase direct current;
A DC-DC boost converter for keeping the three-phase DC converted by the three-phase rectifier constant in correspondence with the maximum current command value detected by the main controller;
A three-phase inverter for converting the direct current maintained in the DC-DC boost converter into three-phase alternating current;
And a second detecting section for detecting an output current and a voltage of the DC-DC boost converter,
Wherein the main control unit controls the three-phase inverter with the voltage and current detected from the second detection unit, detects the generation voltage and current from the first detector every predetermined period (T1), and detects the detected generation voltage And if the voltage is equal to or greater than the minimum voltage, transmits the generated power to the wind turbine. The method of claim 2, wherein, when the generated voltage is equal to or greater than the minimum voltage, the main controller uses a maximum power detection table storing a line voltage, a line current, and a maximum current command value for each angular velocity of the rotor, The current command value is compared with the current power, and if the current power is greater than the previous power, the maximum current command value is increased. If the current power is less than the previous power, the maximum current command value is decreased And controls the pulse-width-modulated control signal through the IGBT control board to control the DC-DC boost converter. delete delete

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