CN109980980A - Voltage control device and method of converter and converter - Google Patents

Abstract

The invention discloses a voltage control device and method of a converter and the converter. The device comprises a first comparison module, a first feedback regulation module, a second comparison module and a second feedback regulation module which are connected in sequence; the first input end of the first comparison module receives an input voltage given value of the converter, the second input end of the first comparison module receives a feedback voltage value of the converter, the first feedback regulation module outputs a current given value according to a comparison result of the first comparison module, the first input end of the second comparison module receives the current given value output by the first comparison module, the second input end of the second comparison module receives a current feedback value of the converter, and the second feedback regulation module outputs a Pulse Width Modulation (PWM) signal for driving an Insulated Gate Bipolar Transistor (IGBT) in the converter according to the comparison result of the second comparison module so as to regulate the input voltage of the converter. By adopting the technical scheme in the embodiment of the invention, the response speed to the voltage control of the converter can be improved.

Description

Voltage control device and method of converter, converter

technical field

The present invention relates to the technical field of wind power generation, in particular to a voltage control device and method of a converter, and a converter.

Background technique

The rectified power generation of the wind turbine needs to be integrated into the grid through the converter. When the power grid is unstable, such as the grid voltage rises or falls, the energy that can be integrated into the grid decreases, but the output power of the wind turbine remains unchanged temporarily, causing fluctuations in the input voltage of the converter.

In order to control the fluctuation of the input voltage of the converter, the method in the prior art is that the PI regulator obtains the modulation voltage duty cycle according to the voltage error obtained by subtracting the input voltage given value of the converter and the voltage feedback value, Then it is converted into a PWM signal by the PWM generator to drive the IGBT in the control object, that is, the input current of the converter is controlled according to the voltage difference signal.

However, the inventors of the present application found that the method of controlling the input current of the converter according to the voltage difference signal in the prior art needs to convert the feedback voltage signal of the converter into a current signal first. Due to the voltage-current conversion step in the control link, the response rate to the voltage control of the converter is reduced.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a voltage control device and method for a converter, and a converter, which can improve the response rate to the voltage control of the converter.

In a first aspect, an embodiment of the present invention provides a voltage control device for a converter, the device includes a first comparison module, a first feedback adjustment module, a second comparison module, and a second feedback adjustment module connected in sequence; wherein, The first input terminal of the first comparison module receives the input voltage given value of the converter, the second input terminal of the first comparison module receives the feedback voltage value of the converter, and the first feedback adjustment module is based on the comparison of the first comparison module. As a result, the given current value is output, the first input terminal of the second comparison module receives the given current value output by the first comparison module, the second input terminal of the second comparison module receives the current feedback value of the converter, and the second feedback adjusts The module outputs a pulse width modulated PWM signal for driving the IGBT in the converter according to the comparison result of the second comparison module, so as to adjust the input voltage of the converter.

In some embodiments of the first aspect, the second feedback regulation module is a hysteresis regulator.

In some embodiments of the first aspect, a current limiter is set on the line between the first feedback adjustment module and the second comparison module, and a current limiter value is preset in the current limiter.

In some embodiments of the first aspect, a line between the first feedback adjustment module and the second comparison module is provided with a first switching device, and the first switching device is used to connect the output end of the converter to a voltage source It is disconnected when it is turned off, and the first input terminal of the second comparison module receives a preset external current given value.

In some embodiments of the first aspect, the converter is a DC/AC converter, and the output end of the DC/AC converter is connected to a three-phase power grid; the second comparison module includes three comparators arranged in parallel, the first The two-feedback adjustment module includes three hysteresis regulators arranged in parallel and connected to the three comparators respectively; the device also includes a phase-locked loop and an operator; wherein, the phase-locked loop obtains the power grid according to the three-phase voltage signal of the three-phase power grid Phase, the operator outputs three current given values according to the current given value output by the first feedback adjustment module and the grid phase, the first end of each comparator receives one current given value, the second of each comparator The terminal receives the current feedback value of the corresponding phase in the three-phase power grid, and each hysteresis regulator outputs the pulse width modulation PWM signal used to drive the corresponding IGBT in the DC/AC converter according to the comparison result of the corresponding comparator to adjust the DC/AC The input voltage of the AC converter.

In some embodiments of the first aspect, a line between the first feedback adjustment module and the second comparison module is provided with a second switching device, and the second switching device is used to connect to the DC/AC converter on the DC side. When the voltage source is on, it is disconnected, and the first input terminal of the second comparison module receives a preset external current given value.

In a second aspect, an embodiment of the present invention provides a voltage control method for a converter, the method comprising:

The first feedback adjustment module outputs the current given value according to the input voltage given value of the converter and the feedback voltage value of the converter;

The second feedback regulation module outputs a PWM signal for driving the IGBT in the converter according to the current given value output by the first feedback regulation module and the current feedback value of the converter to adjust the input voltage of the converter.

In some embodiments of the second aspect, when the output terminal of the converter is connected to the voltage source, the first switching device is controlled to be disconnected, and the second feedback adjustment module is controlled to receive a preset external current given value.

In some embodiments of the second aspect, the converter is a DC/AC converter, and the output end of the DC/AC converter is connected to a three-phase power grid; the second feedback adjustment module includes three hysteresis regulators arranged in parallel The device also includes a phase-locked loop and an operator; the method further includes: obtaining the grid phase by the phase-locked loop according to the three-phase voltage signal of the three-phase grid; adjusting the current given value and the grid output by the operator according to the first feedback adjustment module Phase, output three current given values; each hysteresis regulator outputs the PWM used to drive the corresponding IGBT in the DC/AC converter according to one current given value and the current feedback value of the corresponding phase in the three-phase power grid signal to adjust the input voltage of the DC/AC converter.

In a third aspect, an embodiment of the present invention provides a converter, where the converter includes the voltage control device of the converter as described above.

As described above, the voltage control device of the converter in the embodiment of the present invention adds the second comparison module and the second feedback adjustment module on the basis of the first comparison module and the first feedback adjustment module, and establishes the The current inner loop control mechanism of the input voltage of the device. Compared with the prior art, which needs to convert the feedback voltage signal of the converter into a current signal (voltage outer loop) first, and needs to wait until the output voltage changes sufficiently, the correction effect can be generated. The inner loop has the advantage of fast response. When the input current of the converter decreases, the duty cycle of the PWM signal in the second feedback adjustment module will be updated immediately, thereby avoiding unnecessary fluctuations in the output voltage and making the converter's The supply voltage is more stable.

Description of drawings

The present invention can be better understood from the following description of specific embodiments of the present invention in conjunction with the accompanying drawings, wherein the same or similar reference numerals denote the same or similar features.

FIG. 1 is a schematic structural diagram of a voltage control device of a converter according to an embodiment of the present invention;

2 is a schematic structural diagram of a voltage control device for a converter according to another embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a voltage control device for a converter according to another embodiment of the present invention;

4 is a schematic flowchart of a voltage control method for a converter according to an embodiment of the present invention;

FIG. 5 is a schematic flowchart of a voltage control method for a converter according to another embodiment of the present invention.

Description of reference numbers:

101 - the first comparison module; 102 - the first feedback adjustment module; 103 - the second comparison module;

104 - the second feedback adjustment module; 105 - the converter; 1011 - the first comparator;

1021-PI regulator; 1031-second comparator; 1041-hysteresis regulator;

1051-DC/AC converter; 302-phase-locked loop; 303-calculator.

Detailed ways

Features and exemplary embodiments of various aspects of embodiments of the present invention are described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present invention.

The embodiments of the present invention provide a voltage control device and method for a converter, and a converter, which are used to control the input voltage of the converter of a wind turbine. By using the technical solutions in the embodiments of the present invention, the Setting the current inner loop increases the response rate to the converter voltage control.

FIG. 1 is a schematic structural diagram of a voltage control device of a converter 105 according to an embodiment of the present invention. As shown in FIG. 1 , the voltage control device of the converter 105 includes a first comparison module 101 , a first feedback adjustment module 102 , a second comparison module 103 and a second feedback adjustment module 104 which are connected in sequence.

The first input terminal of the first comparison module 101 receives the input voltage given value U* of the converter 105, the second input terminal of the first comparison module 101 receives the feedback voltage value u of the converter 105, and the first feedback The adjustment module 102 outputs a given current value I* according to the comparison result of the first comparison module 101, the first input terminal of the second comparison module 103 receives the given current value I* output by the first comparison module 101, and the second comparison module 103 The second input terminal of the converter 105 receives the current feedback value i of the converter 105, and the second feedback adjustment module 104 outputs a pulse width modulated PWM signal for driving the IGBT in the converter 105 according to the comparison result of the second comparison module 103, so as to The input voltage of the converter 105 is adjusted.

As described above, the voltage control device of the converter 105 in the embodiment of the present invention adds the second comparison module 103 and the second feedback adjustment module 104 on the basis of the first comparison module 101 and the first feedback adjustment module 102, A current inner loop control mechanism for the input voltage of the converter 105 is established. Compared with the prior art, which needs to first convert the feedback voltage signal of the converter 105 into a current signal (voltage outer loop), and needs to wait until the output voltage changes sufficiently, the correction effect can be generated. The current inner loop has the advantage of fast response. When the input current of the converter 105 decreases, the duty cycle of the PWM signal in the second feedback adjustment module 104 will be updated immediately, so as to avoid unnecessary fluctuations in the output voltage and make the inverter The supply voltage of the current transformer 105 is more stable.

In addition, the reduction of the voltage fluctuation of the converter 105 means that the capacitance value of the converter 105 can be selected to be smaller, which is beneficial to reduce the cost and volume of the converter 105 .

FIG. 2 is a schematic structural diagram of a voltage control device of a converter according to another embodiment of the present invention. The difference between FIG. 2 and FIG. 1 is that the first feedback adjustment module 102 in FIG. 2 is specifically a PI regulator 1021, the second feedback adjustment module 104 is specifically a hysteresis regulator 1041, and the first comparison module 101 is specifically a first comparison module 101. A comparator 1011 , and the second comparison module 103 is specifically a second comparator 1031 .

Compared with other types of feedback regulators, the hysteresis regulator 1041 has the advantage of fast response speed. Therefore, in the embodiment of the present invention, the second feedback regulation module 104 is preferably the hysteresis regulator 1041 .

The working principle of the voltage control device of the converter 105 in the example of FIG. 2 is as follows: the first input terminal of the first comparator 1011 receives the input voltage given value U* of the converter 105 , and the first input terminal of the first comparator 1011 The two input terminals receive the feedback voltage value u of the converter 105, the PI regulator 1021 outputs a given current value I* according to the comparison result U*-u of the first comparator 1011, and the first input terminal of the second comparator 1031 receives The given current value I* output by the first comparator 1011, the second input terminal of the second comparator 1031 receives the current feedback value i of the converter 105, and the hysteresis regulator 1041 according to the comparison result I of the second comparator 1031 *-i outputs a pulse width modulated PWM signal for driving the IGBTs in the converter 105 to adjust the input voltage of the converter 105 .

According to the embodiment of the present invention, in order to prevent the situation that the input current of the converter 105 is too large, the current setting value I* output by the PI regulator 1021 can also be limited. A current limiter (not shown in the figure) is set on the line between the second comparator 1031 , and a current limit value is preset in the current limiter, such as the maximum operating current of the converter 105 . With this setting, when the load suddenly increases, once the current given signal reaches the maximum, it will be limited, so that the system will run at the maximum current, thus avoiding the overcurrent fault problem caused by the unlimited current during heavy-load operation.

According to the embodiment of the present invention, in some working conditions that only need to supply current to the input of the converter 105 , such as when the output terminal of the converter 105 is connected to a voltage source, the voltage outer loop can be disconnected. For example, a first switching device (not shown in the figure) is provided on the line between the PI regulator 1021 and the second comparator 1031, which is disconnected when the output end of the converter 105 is connected to the voltage source, and The first input terminal of the second comparison module 103 receives a preset external current given value (eg, the current given signal is directly set by the user). In this way, the input power of the converter 105 is controlled on the one hand, and the power output to the voltage source is controlled on the other hand, so as to achieve precise control of the converter 105 . In addition, in order to flexibly respond to different working conditions, the two working modes can be switched online.

It should be noted that the converters in the wind turbine include DC/DC converters and DC/AC converters. When the converters are DC/DC converters, you can directly follow the wiring method in Figure 2 The voltage control device of the converter in the embodiment of the present invention is constructed. When the converter is a DC/AC converter, since the output end of the DC/AC converter is connected to a three-phase power grid, the voltage control device of the converter in FIG. 2 needs to be adjusted.

FIG. 3 is a schematic structural diagram of a voltage control device for a converter according to still another embodiment of the present invention, which is used to show that when the converter is a DC/AC converter, the components of the voltage control device for the converter connection structure. The difference from FIG. 2 is that the voltage control device of the converter in FIG. 3 further includes a phase-locked loop 302 and an operator 303, and the second comparison module 103 includes three comparators arranged in parallel, and the second feedback adjustment module 104 includes three hysteresis regulators arranged in parallel and connected to the three comparators, respectively.

The working principle of the voltage control device of the DC/AC converter 1051 in the example of FIG. 3 is:

The first input terminal of the first comparator 1011 receives the input voltage given value U _dc * of the converter, and the second input terminal of the first comparator 1011 receives the feedback voltage value U _dc of the converter. A comparison result of the comparator 1011 U _dc *-U _dc output current given value I _dc ^* ; the phase-locked loop 302 obtains the grid phase θ according to the three-phase voltage signals (U _a , U _b , U _c ) of the three-phase grid, The calculator 303 outputs the three-way current given value according to the current given value I _dc ^* output by the PI regulator and the grid phase θ The first end of each comparator receives a given current value, the second end of each comparator receives the current feedback value of the corresponding phase in the three-phase power grid, and each hysteresis regulator outputs the output signal according to the comparison result of the corresponding comparator. The pulse width modulation PWM signal corresponding to the IGBT in the driving DC/AC converter 1051 is used to adjust the input voltage of the DC/AC converter 1051 .

According to the embodiment of the present invention, when U _a , U _b and U _c are three-phase voltage sources, by controlling the alternating current and the direct voltage at the same time, the direct current voltage can have good stability.

When the DC side is connected to a voltage source, the voltage loop can be disconnected. For example, a second switching device may be provided on the line between the PI regulator and the second comparison module 103, and the second switching device is used to disconnect when the DC side of the DC/AC converter 1051 is connected to the voltage source , and the preset external current given value I _dc ^* is received by the first input terminal of the second comparison module 103 , for example, I _dc ^* is directly given by the user to control the input to the DC side of the DC/AC converter 1051 of power.

FIG. 4 is a schematic flowchart of a voltage control method of a converter according to an embodiment of the present invention, which is used for the voltage control device of the converter in FIGS. 1 and 2 . Steps 401 to 404 are shown in FIG. 4 .

In step 401 , the input voltage given value of the converter is received by the first input terminal of the first comparison module 101 , and the feedback voltage value of the converter is received by the second input terminal of the first comparison module 101 .

In step 402 , the given current value is output by the first feedback adjustment module 102 according to the comparison result of the first comparison module 101 .

In step 403, the first input terminal of the second comparison module 103 receives the current given value output by the first comparison module 101, and the second input terminal of the second comparison module 103 receives the current feedback value of the converter.

In step 404, the second feedback adjustment module 104 outputs a PWM signal for driving the IGBT in the converter according to the comparison result of the second comparison module 103, so as to adjust the input voltage of the converter.

According to the embodiments of the present invention, under some working conditions that only need to supply current to the input of the converter, the first switching device can be controlled to be disconnected when the output end of the converter is connected to the voltage source, and the second switching device can be controlled to turn off when the output end of the converter is connected to the voltage source. The first input terminal of the comparison module 103 receives a preset external current given value.

FIG. 5 is a schematic flowchart of a voltage control method for a converter according to another embodiment of the present invention, which is used to control the voltage of the DC/AC converter 1051 in FIG. 3 . The difference between FIG. 5 and FIG. 4 is that FIG. 5 further includes steps 405 to 408 .

In step 405, the phase of the grid is obtained by the phase-locked loop 302 according to the three-phase voltage signal of the three-phase grid.

In step 406, the calculator 303 outputs the three-way current given value according to the current given value and the grid phase output by the first feedback adjustment module 102.

In step 407, the first terminal of each comparator receives a current given value, and the second terminal of each comparator receives the current feedback value of the corresponding phase in the three-phase power grid.

In step 408 , each hysteresis regulator outputs a pulse width modulated PWM signal for driving the corresponding IGBT in the DC/AC converter 1051 according to the comparison result of the corresponding comparator, so as to adjust the DC/AC converter 1051 Input voltage.

An embodiment of the present invention also provides a converter, which includes the above-mentioned voltage control device for the converter.

It should be clear that each embodiment in this specification is described in a progressive manner, and the same or similar parts of each embodiment may be referred to each other, and each embodiment focuses on the differences from other embodiments. place. For the apparatus embodiment, reference may be made to the description part of the method embodiment for relevant places. Embodiments of the present invention are not limited to the specific steps and structures described above and shown in the figures. Those skilled in the art may make various changes, modifications and additions, or change the order between steps, after comprehending the spirit of the embodiments of the present invention. Also, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

The functional blocks shown in the above-described structural block diagrams may be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, it may be, for example, an electronic circuit, an application specific integrated circuit (ASIC), suitable firmware, a plug-in, a function card, or the like. When implemented in software, elements of embodiments of the invention are programs or code segments used to perform the required tasks. The program or code segments may be stored in a machine-readable medium or transmitted over a transmission medium or communication link by a data signal carried in a carrier wave. A "machine-readable medium" may include any medium that can store or transmit information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, and the like. The code segments may be downloaded via a computer network such as the Internet, an intranet, or the like.

The embodiments of the present invention may be implemented in other specific forms without departing from the spirit and essential characteristics thereof. For example, the algorithms described in particular embodiments may be modified without departing from the basic spirit of the embodiments of the invention in system architecture. Accordingly, the present embodiments are to be regarded in all respects as illustrative and not restrictive, and the scope of the embodiments of the present invention is defined by the appended claims rather than the foregoing description, and falls within the meaning and equivalence of the claims All changes within the scope of the present invention are thus included in the scope of the embodiments of the present invention.

Claims (10)

1. The voltage control device of the converter is characterized by comprising a first comparison module, a first feedback regulation module, a second comparison module and a second feedback regulation module which are sequentially connected; wherein,

a first input end of the first comparison module receives an input voltage given value of the current transformer, and a second input end of the first comparison module receives a feedback voltage value of the current transformer;

the first feedback adjusting module outputs a given current value according to the comparison result of the first comparing module;

a first input end of the second comparison module receives a given current value output by the first comparison module, and a second input end of the second comparison module receives a current feedback value of the converter;

and the second feedback adjusting module outputs a Pulse Width Modulation (PWM) signal for driving an Insulated Gate Bipolar Transistor (IGBT) in the converter according to the comparison result of the second comparing module so as to adjust the input voltage of the converter.

2. The apparatus of claim 1, wherein the second feedback regulation module is a hysteresis regulator.

3. The apparatus of claim 2, wherein a current limiter is disposed in a line between the first feedback regulation module and the second comparison module.

4. The apparatus of claim 2, wherein a first switching device is disposed on a line between the first feedback regulation module and the second comparison module, the first switching device is configured to be turned off when the output of the converter is connected to a voltage source, and the first input of the second comparison module receives a predetermined external current setpoint.

5. The device of claim 1, wherein the converter is a DC/AC converter, and an output end of the DC/AC converter is connected to a three-phase grid;

the second comparison module comprises three comparators arranged in parallel, and the second feedback regulation module comprises three hysteresis regulators arranged in parallel and respectively connected with the three comparators;

the device also comprises a phase-locked loop and an arithmetic unit; wherein,

the phase-locked loop obtains a power grid phase according to the three-phase voltage signal of the three-phase power grid;

the arithmetic unit outputs three current set values according to the current set value output by the first feedback regulation module and the power grid phase;

the first end of each comparator receives one path of current given value, the second end of each comparator receives a current feedback value of a corresponding phase in a three-phase power grid, and each hysteresis regulator outputs a Pulse Width Modulation (PWM) signal for driving a corresponding Insulated Gate Bipolar Transistor (IGBT) in the DC/AC converter according to a comparison result of the corresponding comparator so as to adjust the input voltage of the DC/AC converter.

6. The apparatus of claim 5, wherein a second switching device is disposed on a line between the first feedback regulating module and the second comparing module, the second switching device is configured to be turned off when the DC side of the DC/AC converter is connected to a voltage source, and the first input terminal of the second comparing module receives a preset external current setpoint.

7. A voltage control method of a converter is characterized by comprising the following steps:

a first feedback regulation module outputs a given current value according to a given input voltage value of the converter and a given feedback voltage value of the converter;

and outputting a PWM (pulse-width modulation) signal for driving the IGBT (insulated gate bipolar translator) in the converter by a second feedback regulation module according to the current given value output by the first feedback regulation module and the current feedback value of the converter so as to regulate the input voltage of the converter.

8. The method of claim 7, further comprising: when the output end of the converter is connected to a voltage source, the first switching device is controlled to be switched off, and the second feedback adjusting module is controlled to receive a preset external current given value.

9. The method of claim 7, wherein the converter is a DC/AC converter, and the output of the DC/AC converter is connected to a three-phase grid; the second feedback regulation module comprises three hysteresis regulators which are arranged in parallel;

the method further comprises the following steps:

obtaining a power grid phase by a phase-locked loop according to the three-phase voltage signal of the three-phase power grid;

outputting three current set values by an arithmetic unit according to the current set value output by the first feedback adjusting module and the power grid phase;

and each hysteresis regulator outputs a PWM signal for driving a corresponding IGBT in the DC/AC converter according to a given current value and a current feedback value of a corresponding phase in a three-phase power grid so as to adjust the input voltage of the DC/AC converter.

10. A converter, characterized in that it comprises a voltage control device of a converter according to any of claims 1-6.