CN117293918A - Photovoltaic panel output voltage control method based on disturbance observation method - Google Patents
Photovoltaic panel output voltage control method based on disturbance observation method Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
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- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/66—Regulating electric power
- G05F1/67—Regulating electric power to the maximum power available from a generator, e.g. from solar cell
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Abstract
The invention discloses a photovoltaic panel output voltage control method based on a disturbance observation method, wherein a modulation module connected with a transistor in a photovoltaic panel boost conversion circuit is arranged on the transistor, and MPPT tracking of the photovoltaic panel is performed by using the disturbance observation method and a maximum output voltage limiting algorithm based on the modulation module, and the method specifically comprises the following steps: the MPPT module generates an MPPT duty ratio output value corresponding to the transistor by utilizing the real-time output voltage and the real-time output current of the photovoltaic panel, and acquires a limit value by utilizing a maximum output voltage limit algorithm through the voltage bus limiter; the difference value between the MPPT duty cycle output value and the limiting value, namely the switch duty cycle, is obtained through an operation module, is input into a modulator, the switch duty cycle is converted into a PWM pulse signal through the modulator, and disturbance is applied to the transistor duty cycle through the PWM pulse signal until the output voltage of the photovoltaic panel is equal to the voltage value corresponding to the maximum power point MPP, so that the voltage of the voltage bus is limited, and the tracking of the maximum power point MPP is realized on the basis.
Description
Technical Field
The invention relates to the field of photovoltaic panel output voltage control, in particular to a photovoltaic panel output voltage control method based on a disturbance observation method.
Background
In recent years, clean energy in China is developed and utilized on a large scale, the ratio of new energy represented by photovoltaic in an energy structure is gradually increased, and a grid-connected inverter is used as a core device for grid connection of new energy photovoltaic power generation, and the control performance of the grid-connected inverter directly influences the efficiency of a power generation system. The inverter may inject power into the grid and may receive energy from both photovoltaic and battery sources. The DC-DC input stage (photovoltaic panel boost conversion circuit) of the inverter is responsible for processing the power supplied by the photovoltaic Panel (PV) and outputting it through the voltage bus (or intermediate bus) after processing, the PV output voltage varies with current and also varies with the environment (solar irradiance, temperature) due to the characteristics of the PV, so the photovoltaic panel has a so-called Maximum Power Point (MPP), which means that for a given temperature and a given solar irradiance, only one voltage and current combination, the output power reaches maximum, and in addition, when the output power of the corresponding boost converter of the DC-DC input stage is smaller than the input power, the voltage rise of the intermediate bus causes the boost converter of the DC-DC input stage to be damaged, so in order to make the grid-connected inverter output high-quality stable power efficiently without damaging the boost converter, it is particularly important to avoid the problem that the boost converter of the DC-DC input stage is damaged due to the intermediate bus rise while keeping the DC-DC converter always operating at the maximum power point MPP.
Disclosure of Invention
In order to enable the grid-connected inverter to efficiently output high-quality and stable electric energy on the basis of not damaging the boost converter, the invention provides a photovoltaic panel output voltage control method based on a disturbance observation method, and MPPT tracking of a photovoltaic panel is performed through the disturbance observation method and a maximum output voltage limiting algorithm; it is applied to photovoltaic board boost converting circuit, photovoltaic board boost converting circuit includes: the device comprises a boost converter, a voltage bus, an output voltage monitoring circuit and an output current monitoring circuit; the boost converter includes: the device comprises an inductor, a transistor, a diode, a capacitor and a modulation module, wherein the inductor, the transistor, the diode, the capacitor and the modulation module are arranged between a positive power supply of a photovoltaic panel and an output end of a voltage bus and are electrically connected in sequence; the modulation module comprises an MPPT module, an operation module and a modulator which are sequentially connected; the control method comprises the following steps:
determining a voltage value corresponding to a maximum power point MPP through a photovoltaic output curve;
measuring the real-time output voltage and the real-time output current of the photovoltaic panel through an output voltage monitoring circuit and an output current monitoring circuit and inputting the real-time output voltage and the real-time output current into an MPPT module;
generating an MPPT duty ratio output value corresponding to the transistor by utilizing the real-time output voltage and the real-time output current through an MPPT module, and acquiring a limit value by utilizing a maximum output voltage limit algorithm through a voltage bus voltage limiter;
obtaining a difference value between an MPPT duty cycle output value and a limiting value, namely a switch duty cycle, through an operation module, and inputting the difference value into a modulator;
the switching duty ratio is converted into a PWM pulse signal through the modulator, and disturbance is applied to the transistor duty ratio through the PWM pulse signal until the output voltage of the photovoltaic panel is equal to a voltage value corresponding to the maximum power point MPP, so that the working power point in the photovoltaic output curve is controlled by changing the current extracted from the photovoltaic panel, and the boost converter always works at the maximum power point.
Further, the abscissa of the photovoltaic output curve is the output voltage of the photovoltaic panel, the ordinate is the output current of the photovoltaic panel, the maximum output voltage of the photovoltaic output curve is the open-circuit voltage, namely the output voltage of the photovoltaic panel when no current is extracted, and the maximum output current of the photovoltaic output curve is the maximum output current of the photovoltaic panel.
Further, the voltage bus limiter comprises: an arithmetic unit and a PI controller; the PI controller comprises a first operation path, a second operation path and a fusion unit; the maximum output voltage limiting algorithm includes:
setting a maximum working voltage corresponding to the voltage bus through an operation unit, acquiring the current voltage of the voltage bus, acquiring the difference value between the maximum working voltage and the current voltage of the voltage bus as a value to be regulated, and inputting the difference value into a PI controller;
kp proportion adjustment is carried out on the value to be adjusted through a first operation path to obtain a first adjustment value, and Ki integral adjustment and differential operation are sequentially carried out on the value to be adjusted through a second operation path to obtain a second adjustment value;
and obtaining the sum of the first adjustment value and the second adjustment value through the fusion unit, obtaining a limiting value, and inputting the limiting value into an operation module in the modulation module.
Further, in the boost converter: one end of the inductor is connected with a positive power supply of the photovoltaic panel, the other end of the inductor is connected with a drain electrode of the transistor and then connected with a positive electrode of the diode, and a negative electrode end of the diode is connected with one end of the capacitor and then connected with a voltage bus output end; the other end of the capacitor is grounded; the source electrode of the transistor is grounded, and the grid electrode of the transistor is connected with the modulation module; the negative electrode of the photovoltaic panel is grounded; the modulation module is used for modulating the duty ratio of the transistor.
Further, when the transistor is in a conducting state, a first path formed by the photovoltaic panel positive power supply, the inductor and the transistor is in a conducting state, and at this time, the inductor is used for storing electric energy output by the photovoltaic panel.
Further, when the second path formed by the positive power supply, the inductor, the transistor, the diode and the capacitor of the photovoltaic panel is in a conducting state, the photovoltaic panel and the charged inductor output electric energy to a load connected with the output end of the voltage bus, and the voltage value on the voltage bus is larger than the output voltage of the photovoltaic panel.
Compared with the prior art, the invention at least has the following beneficial effects:
(1) The invention sets a modulation module connected with a transistor in a photovoltaic panel boost conversion circuit, and carries out MPPT tracking of the photovoltaic panel by utilizing a disturbance observation method and a maximum output voltage limiting algorithm based on the modulation module, and specifically comprises the following steps: the MPPT module generates an MPPT duty ratio output value corresponding to the transistor by utilizing the real-time output voltage and the real-time output current of the photovoltaic panel, and acquires a limit value by utilizing a maximum output voltage limit algorithm through the voltage bus limiter; the method comprises the steps that a difference value between an MPPT duty ratio output value and a limiting value, namely a switch duty ratio, is obtained through an operation module, and is input into a modulator, the switch duty ratio is converted into a PWM pulse signal through the modulator, and disturbance is applied to the transistor duty ratio through the PWM pulse signal until the output voltage of a photovoltaic panel is equal to a voltage value corresponding to a maximum power point MPP, the limiting value calculated by a voltage bus voltage limiter is introduced into the operation module of the modulation module, and the switch duty ratio is calculated through the MPPT duty ratio output value and the limiting value, so that the limitation of voltage bus voltage is realized, and the tracking of the maximum power point MPP is realized on the basis, and therefore, the high-quality, stable and high-efficiency electric energy output of the boost converter is realized on the basis that the boost converter is not damaged;
(2) In the invention, the transistor is controlled to be in a conducting state, so that a first path formed by the positive power supply of the photovoltaic panel, the inductor and the transistor is conducted, the inductor stores electric energy output by the photovoltaic panel, and when a second path formed by the positive power supply of the photovoltaic panel, the inductor, the transistor, the diode and the capacitor is conducted, the photovoltaic panel and the charged inductor both output electric energy to a load connected with the output end of the voltage bus, thereby enabling the voltage of the voltage bus to be higher than the output voltage of the photovoltaic panel, realizing the efficient output of the photovoltaic panel, and improving the utilization rate of the electric energy output by the photovoltaic panel.
Drawings
FIG. 1 is a flow chart of a method for controlling output voltage of a photovoltaic panel based on disturbance observation;
FIG. 2 is a circuit diagram of a photovoltaic panel boost conversion circuit;
FIG. 3 is a circuit diagram of a photovoltaic panel dual boost conversion circuit;
FIG. 4 is a diagram of an output voltage monitoring circuit;
FIG. 5 is a diagram of an output current monitoring circuit;
FIG. 6 is a control block diagram of a modulation module;
FIG. 7 is a control block diagram of a voltage bus limiter;
fig. 8 is a graph of photovoltaic output.
In the figure:
1. an operation module; 2. an arithmetic unit; 3. and a fusion unit.
Detailed Description
The following are specific embodiments of the present invention and the technical solutions of the present invention will be further described with reference to the accompanying drawings, but the present invention is not limited to these embodiments.
Example 1
In order to ensure that the boost converter always works on the maximum power point on the basis of not damaging the boost converter, so that the grid-connected inverter outputs high-quality and stable electric energy efficiently, as shown in fig. 1, the invention provides a photovoltaic panel output voltage control method based on a disturbance observation method, and MPPT tracking of a photovoltaic panel is performed through the disturbance observation method and a maximum output voltage limiting algorithm; it is applied to photovoltaic board boost converting circuit, photovoltaic board boost converting circuit includes: the device comprises a boost converter, a voltage bus, an output voltage monitoring circuit and an output current monitoring circuit; as shown in fig. 2, the boost converter includes: the modulation module is arranged between the positive power supply of the photovoltaic panel and the output end of the voltage bus and is electrically connected with the inductor L1, the transistor Q1, the diode D1, the capacitor C1 and the transistor Q1 in sequence;
the boost converter comprises: one end of the inductor L1 is connected with a positive power supply of the photovoltaic panel PV1, the other end of the inductor L1 is connected with a drain electrode of the transistor Q1 and then connected with a positive electrode of the diode D1, and a negative end of the diode D1 is connected with one end of the capacitor C1 and then connected with a voltage bus output end; the other end of the capacitor C1 is grounded; the source electrode of the transistor Q1 is grounded, and the grid electrode is connected with the modulation module; the negative electrode of the photovoltaic panel PV1 is grounded; the modulation module is used for modulating the duty ratio of the transistor Q1.
When the transistor Q1 is in the on state, a first path formed by the positive power supply of the photovoltaic panel PV1, the inductor L1 and the transistor Q1 is in the on state, and at this time, the inductor L1 is used for storing the electric energy output by the photovoltaic panel PV 1.
When the second path formed by the positive power supply of the photovoltaic panel PV1, the inductor L1, the transistor Q1, the diode D1 and the capacitor C1 is in a conductive state, the photovoltaic panel PV1 and the charged inductor L1 output electric energy to the load connected to the output terminal of the voltage bus, and at this time, the voltage value on the voltage bus is greater than the output voltage of the photovoltaic panel.
In the invention, the transistor Q1 is controlled to be in a conducting state, so that a first path formed by the positive power supply of the photovoltaic panel PV1, the inductor L1 and the transistor Q1 is conducted, the inductor L1 stores electric energy output by the photovoltaic panel PV1, and when a second path formed by the positive power supply of the photovoltaic panel PV1, the inductor L1, the transistor Q1, the diode D1 and the capacitor C1 is conducted, the photovoltaic panel PV1 and the charged inductor L1 all output electric energy to a load connected with the output end of the voltage bus, so that the voltage of the voltage bus is higher than the output voltage of the photovoltaic panel PV1, the efficient output of the photovoltaic panel PV1 is realized, and the utilization rate of the electric energy output by the photovoltaic panel PV1 is improved.
From a simplification perspective, the photovoltaic panel can be regarded as a current source. The output voltage of a photovoltaic panel varies with the output current, and therefore the photovoltaic panel has a so-called Maximum Power Point (MPP), which means that for a given temperature and a given solar irradiance, there is only one combination of voltage and current, the output power is maximized. In order to keep the boost converter (DC-DC converter) operating at MPP all the time, an algorithm implementing MPPT (maximum power point tracking) is required. Based on the good adaptability of the P & O algorithm to different photovoltaic conditions (operational and environmental variations) and the high tracking factor, the invention selects the P & O algorithm to control the output of the boost converter.
As shown in fig. 6, the modulation module includes an MPPT module, an operation module 1 and a modulator connected in sequence;
in detail, in fig. 6 and 7, ipv represents a real-time output current measured by the output current monitoring circuit, vpv represents a real-time output voltage measured by the output voltage monitoring circuit, MPPT represents an MPPT module, d_mppt represents an MPPT duty cycle output value, d_mod represents a switching duty cycle, d_boost represents a PWM pulse signal, vbus represents a current voltage of the voltage bus, vbus_limit represents a maximum operating voltage corresponding to the voltage bus, d_limit represents a limit value, modulator represents a Modulator, control represents a PI controller, kp represents Kp proportional adjustment, ki represents Ki integral adjustment, and ∈dt represents differential operation.
The control method comprises the following steps:
determining a voltage value corresponding to a maximum power point MPP through a photovoltaic output curve;
the abscissa of the photovoltaic output curve is the output voltage of the photovoltaic panel, the ordinate is the output current of the photovoltaic panel, the maximum output voltage of the photovoltaic output curve is the open-circuit voltage Voc, namely the output voltage of the photovoltaic panel when no current is extracted, and the maximum output current of the photovoltaic output curve is the maximum output current Isc of the photovoltaic panel.
The MPP is the most ideal operating point when extracting energy from a photovoltaic panel. However, voc and Isc vary with the temperature of the photovoltaic and the solar irradiance received by the solar cell, and thus, the MPP also varies.
Measuring the real-time output voltage and the real-time output current of the photovoltaic panel through an output voltage monitoring circuit shown in fig. 4 and an output current monitoring circuit shown in fig. 5, and inputting the real-time output voltage and the real-time output current into an MPPT module;
in this embodiment, vpv is connected to the output of the photovoltaic panel PV1 in fig. 4, vpv_sens represents the output of the signal, vpv_sensor is connected to the output of the photovoltaic panel PV1 in fig. 5, and vpv_out represents the output of the signal.
Generating an MPPT duty ratio output value corresponding to the transistor by utilizing the real-time output voltage and the real-time output current through an MPPT module, and acquiring a limit value by utilizing a maximum output voltage limit algorithm through a voltage bus voltage limiter;
as shown in fig. 7, the voltage bus limiter comprises: an arithmetic unit 2 and a PI controller; the PI controller comprises a first operation path, a second operation path and a fusion unit 3;
the voltage bus limiter implements an algorithm responsible for limiting the MPPT duty cycle output value when the voltage of the voltage bus reaches a maximum operating voltage.
The maximum output voltage limiting algorithm includes:
setting a maximum working voltage corresponding to the voltage bus through an operation unit, acquiring the current voltage of the voltage bus, and acquiring the difference value between the maximum working voltage and the current voltage of the voltage bus as a value to be regulated and inputting the difference value into a PI controller when the current voltage of the voltage bus is larger than the maximum working voltage;
kp proportion adjustment is carried out on the value to be adjusted through a first operation path to obtain a first adjustment value, and Ki integral adjustment and differential operation are sequentially carried out on the value to be adjusted through a second operation path to obtain a second adjustment value;
and obtaining the sum of the first adjustment value and the second adjustment value through the fusion unit, obtaining a limiting value, and inputting the limiting value into an operation module in the modulation module.
It should be noted that, the MPPT module receives the real-time output voltage and the real-time output current of the photovoltaic panel, and outputs the d_mppt duty ratio to control the transistor Q1 according to the P & O algorithm. However, since MPPT always seeks to extract maximum power from the photovoltaic panel, if a dc-to-ac output circuit (which is not described in detail in this embodiment) connected to the voltage bus output is connected to the photovoltaic panel boost converter circuit at one end and to the grid at the other end, for transmitting the electrical energy processed by the photovoltaic panel boost converter circuit to the grid), it is not possible to transmit the total available energy to the grid, which may result in an intermediate dc bus (i.e., voltage bus) capacitor overvoltage. This occurs mainly in two cases: firstly, when the boost converter is switching on the photovoltaic panel but is still not connected to the grid, and secondly, when the output power has to be reduced, for example in case of an excessive grid frequency, which is required by most grid-connected converter standards regulations. The present invention implements a second algorithm, called "Vbus overvoltage protection", i.e., maximum output voltage limiting algorithm, for limiting the MPPT duty cycle output value, as shown in fig. 7. The output d_limit of the second algorithm, which is zero when the current voltage Vbus of the voltage bus is below vbus_limit and negative above vbus_limit. This negative value, denoted as subtraction in fig. 7, decreases d_mppt to control the Vbus voltage level. The resulting duty cycle, called d_mod (d_mod=d_mppt-d_limit), is finally passed to the modulator, which converts it to the PWM pulse signal required by transistor Q1 via a saturation block.
Obtaining a difference value between an MPPT duty cycle output value and a limiting value, namely a switch duty cycle, through an operation module, and inputting the difference value into a modulator;
the switching duty ratio is converted into a PWM pulse signal through the modulator, and disturbance is applied to the transistor duty ratio through the PWM pulse signal until the output voltage of the photovoltaic panel is equal to a voltage value corresponding to the maximum power point MPP, so that the working power point in the photovoltaic output curve is controlled by changing the current extracted from the photovoltaic panel, and the boost converter always works at the maximum power point.
In the invention, the modulation module applies a disturbance to the operating point of the boost converter (i.e. the d1 duty cycle of the transistor Q1 in fig. 2) by using a P & O (disturbance and observation) algorithm, so as to change the current drawn from the photovoltaic panel PV1 (and thus control the operating point in the photovoltaic output curve), and after each disturbance, the input power is calculated and the next disturbance direction is defined. For example, if the photovoltaic panel PV1 output current increases, the voltage will decrease. As shown in fig. 8, when operating on the right side of the MPP, this means that the power is higher and higher. Thus, P & O will continue to increase current until it passes the MPP. Thereafter, an increase in current will result in a decrease in power and P & O will change direction, thereby decreasing the next current. The P & O will work around the MPP in an unstable manner, always trying to find a point with higher power.
The invention sets a modulation module connected with a transistor in a photovoltaic panel boost conversion circuit, and carries out MPPT tracking of the photovoltaic panel by utilizing a disturbance observation method and a maximum output voltage limiting algorithm based on the modulation module, and specifically comprises the following steps: the MPPT module generates an MPPT duty ratio output value corresponding to the transistor by utilizing the real-time output voltage and the real-time output current of the photovoltaic panel, and acquires a limit value by utilizing a maximum output voltage limit algorithm through the voltage bus limiter; the voltage bus voltage limiter is used for introducing a limit value calculated by the voltage bus voltage limiter into the operation module of the modulation module, and the switch duty ratio is calculated by the MPPT duty ratio output value and the limit value, so that the limit of the voltage bus voltage is realized, and the tracking of the maximum power point MPP is realized on the basis of the limit value.
Example two
As shown in fig. 3, the present invention further provides a photovoltaic panel dual boost conversion circuit, including:
the first boost converter, the second boost converter, the voltage bus, the output voltage monitoring circuit and the output current monitoring circuit corresponding to each boost converter, wherein the first boost converter and the second boost converter comprise an inductor, a transistor, a diode and an energy storage capacitor which are electrically connected in sequence; the first boost converter and the second boost converter share an energy storage capacitor; one end of the first boost converter is connected with the positive electrode of the first photovoltaic panel, and the other end of the first boost converter is connected with the energy storage capacitor and then connected with the voltage bus; one end of the second boost converter is connected with the positive electrode of the second photovoltaic panel, and the other end of the second boost converter is connected with the energy storage capacitor and then connected with the voltage bus; the cathodes of the first photovoltaic plate and the second photovoltaic plate are grounded together;
the first boost converter specifically includes:
the first inductor L1, the first transistor Q1, the first diode D1 and the common energy storage capacitor C1; wherein:
one end of a first inductor L1 is connected with a positive power supply of a first photovoltaic panel PV1, the other end of the first inductor L1 is connected with a drain electrode of a first transistor Q1 and then connected with a positive end of a first diode D1, and a negative end of the first diode D1 is connected with one end of an energy storage capacitor C1 and then connected with a voltage bus output end; the other end of the energy storage capacitor C1 is grounded; the source electrode of the first transistor Q1 is grounded, and the gate electrode is connected to the modulation module in the first embodiment; the negative electrode of the first photovoltaic panel PV1 is grounded; the modulation module is used for modulating the duty ratio of the first transistor.
The second boost converter specifically includes:
a second inductor L2, a second transistor Q2, a second diode D2, and a common energy storage capacitor C1; wherein:
one end of the second inductor L2 is connected with a positive power supply of the second photovoltaic panel PV2, the other end of the second inductor L2 is connected with a drain electrode of the second transistor Q2 and then connected with a positive end of the second diode D2, and a negative end of the second diode D2 is connected to a connecting line between a negative end of the first diode D1 and the energy storage capacitor C1; the source electrode of the second transistor Q2 is grounded, and the gate electrode is connected to the modulation module in the first embodiment; the negative electrode of the second photovoltaic panel PV2 is grounded; the modulation module is used for modulating the duty ratio of the second transistor Q2.
It should be noted that, in this embodiment, each boost converter corresponds to an independent modulation module, that is, a photovoltaic panel output voltage control method based on the disturbance observation method in the present invention may be applied to the modulation module in each boost converter separately for control.
In addition, the boost converters in this embodiment can be controlled independently, each connected to an intermediate voltage bus, meaning that their outputs are connected together, this configuration has several advantages: since each boost converter only handles half of the total output power, the power components can be designed to a lower specification, reducing boost cost and power consumption, and further since each boost converter can be individually modulated with a duty cycle, flexibility in control is improved.
It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present invention are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.
Furthermore, descriptions such as those referred to herein as "first," "second," "a," and the like are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or an implicit indication of the number of features being indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In addition, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the technical solutions, and when the technical solutions are contradictory or cannot be implemented, the combination of the technical solutions should be considered as not existing, and not falling within the scope of protection claimed by the present invention.
Claims (6)
1. The photovoltaic panel output voltage control method based on the disturbance observation method is characterized in that MPPT tracking of the photovoltaic panel is performed through the disturbance observation method and a maximum output voltage limiting algorithm; it is applied to photovoltaic board boost converting circuit, photovoltaic board boost converting circuit includes: the device comprises a boost converter, a voltage bus, an output voltage monitoring circuit and an output current monitoring circuit; the boost converter includes: the device comprises an inductor, a transistor, a diode, a capacitor and a modulation module, wherein the inductor, the transistor, the diode, the capacitor and the modulation module are arranged between a positive power supply of a photovoltaic panel and an output end of a voltage bus and are electrically connected in sequence; the modulation module comprises an MPPT module, an operation module and a modulator which are sequentially connected; the control method comprises the following steps:
determining a voltage value corresponding to a maximum power point MPP through a photovoltaic output curve;
measuring the real-time output voltage and the real-time output current of the photovoltaic panel through an output voltage monitoring circuit and an output current monitoring circuit and inputting the real-time output voltage and the real-time output current into an MPPT module;
generating an MPPT duty ratio output value corresponding to the transistor by utilizing the real-time output voltage and the real-time output current through an MPPT module, and acquiring a limit value by utilizing a maximum output voltage limit algorithm through a voltage bus voltage limiter;
obtaining a difference value between an MPPT duty cycle output value and a limiting value, namely a switch duty cycle, through an operation module, and inputting the difference value into a modulator;
the switching duty ratio is converted into a PWM pulse signal through the modulator, and disturbance is applied to the transistor duty ratio through the PWM pulse signal until the output voltage of the photovoltaic panel is equal to a voltage value corresponding to the maximum power point MPP, so that the working power point in the photovoltaic output curve is controlled by changing the current extracted from the photovoltaic panel, and the boost converter always works at the maximum power point.
2. The method for controlling output voltage of a photovoltaic panel based on disturbance observation according to claim 1, wherein the abscissa of the photovoltaic output curve is output voltage of the photovoltaic panel, the ordinate is output current of the photovoltaic panel, and the maximum output voltage of the photovoltaic output curve is open-circuit voltage, i.e. output voltage of the photovoltaic panel when no current is drawn, and the maximum output current of the photovoltaic output curve is the maximum output current of the photovoltaic panel.
3. The method for controlling the output voltage of a photovoltaic panel based on a disturbance observation method according to claim 2, wherein the voltage bus limiter comprises the following steps: an arithmetic unit and a PI controller; the PI controller comprises a first operation path, a second operation path and a fusion unit; the maximum output voltage limiting algorithm includes:
setting a maximum working voltage corresponding to the voltage bus through an operation unit, acquiring the current voltage of the voltage bus, acquiring the difference value between the maximum working voltage and the current voltage of the voltage bus as a value to be regulated, and inputting the difference value into a PI controller;
kp proportion adjustment is carried out on the value to be adjusted through a first operation path to obtain a first adjustment value, and Ki integral adjustment and differential operation are sequentially carried out on the value to be adjusted through a second operation path to obtain a second adjustment value;
and obtaining the sum of the first adjustment value and the second adjustment value through the fusion unit, obtaining a limiting value, and inputting the limiting value into an operation module in the modulation module.
4. A photovoltaic panel output voltage control method based on disturbance observer method according to claim 3, wherein in the boost converter: one end of the inductor is connected with a positive power supply of the photovoltaic panel, the other end of the inductor is connected with a drain electrode of the transistor and then connected with a positive electrode of the diode, and a negative electrode end of the diode is connected with one end of the capacitor and then connected with a voltage bus output end; the other end of the capacitor is grounded; the source electrode of the transistor is grounded, and the grid electrode of the transistor is connected with the modulation module; the negative electrode of the photovoltaic panel is grounded; the modulation module is used for modulating the duty ratio of the transistor.
5. The method of claim 4, wherein when the transistor is in a conductive state, a first path formed by the positive power supply of the photovoltaic panel, the inductor and the transistor is in a conductive state, and the inductor is used for storing the electric energy output by the photovoltaic panel.
6. The method of claim 5, wherein when the second path formed by the positive power supply, the inductor, the transistor, the diode and the capacitor of the photovoltaic panel is in a conductive state, the photovoltaic panel and the charged inductor output electric energy to a load connected to the output terminal of the voltage bus, and the voltage value on the voltage bus is larger than the output voltage of the photovoltaic panel.
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