CN114389541B - Photovoltaic power generation unit voltage regulation method and system integrating fault information transmission - Google Patents
Photovoltaic power generation unit voltage regulation method and system integrating fault information transmission Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
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- H—ELECTRICITY
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- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
- H02S40/30—Electrical components
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
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- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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Abstract
The invention discloses a photovoltaic power generation unit voltage regulation method and system integrating fault information transmission, comprising the steps of detecting abnormal conditions of a photovoltaic power generation end and acquiring initial fault information of the abnormal conditions; switching carriers with corresponding frequencies based on the initial fault information, and transmitting carrier switching information; in the transmission process, a voltage value output by an output end of the DC-DC converter is obtained, a difference value between the voltage value output by the output end of the DC-DC converter and a given value is made to be different from a carrier signal, and a PWM control signal for controlling a controllable element in the DC-DC converter is generated through a comparator; and controlling a controllable element in the DC-DC converter through the PWM control signal, and demodulating according to the output voltage information of the output end to determine the fault information of the photovoltaic module. According to the scheme, when the photovoltaic module is abnormal, the information of fault occurrence can be obtained by detecting the change conditions of parameters such as output voltage and current of the photovoltaic module.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a photovoltaic power generation unit voltage regulation method and system integrating fault information transmission.
Background
With the rapid growth of the photovoltaic power generation field, the safe operation of the photovoltaic array is gaining more and more attention. Because the photovoltaic power generation needs the photovoltaic panel to be exposed to the outdoor natural environment for a long time, the photovoltaic panel is affected by various environments (such as extreme weather, humidity, dryness and the like), and a series of faults such as cracks, short circuits, open circuits, hot spots and the like of the photovoltaic panel are inevitably caused. With the large-scale deployment of the photovoltaic power generation assembly, the problem of faults can make the power generation capacity and the safety of the whole power generation system extremely challenging. The fault problem is found in time, so that the corresponding fault is reasonably solved, and the method becomes one of the important research points of the photovoltaic power generation at the present stage.
The photovoltaic fault detection at the present stage mainly comprises a physical detection method, an energy meter algorithm, a characteristic calculation method, a time sequence parameter method and the like. Through physical means such as thermal imaging, through analyzing the physical characteristics of photovoltaic power generation module, the fault detection of the photovoltaic power generation module that accomplishes: benatto g.a.d.r. Et al uses an unmanned aerial vehicle to take an electroluminescent image of a photovoltaic array under high irradiance conditions to identify faults related to power loss by image information; although the method can finish the fault detection of the photovoltaic power generation plate without contacting the photovoltaic plate, the method has high cost, and the detection result is greatly influenced by environmental factors. Calculating theoretical output energy according to the setting of the photovoltaic panel parameters, obtaining a difference value between the theoretical output energy and the actual output energy, and using the difference value as a basis of fault diagnosis: dhimish M. substituting the power loss and the voltage loss into a cubic polynomial function to obtain a fault limit curve, and combining with a fuzzy reasoning system to improve the fault recognition rate; however, the method is too dependent on the accuracy of the simulation model, and meanwhile, the aging problem of the photovoltaic power generation module can bring great influence to the detection result. The characteristic calculation method is to identify various fault types by measuring electrical parameters such as voltage, current and the like output by the photovoltaic module and combining parameter setting of the system: gan Yutao et al propose a fault diagnosis method based on a self-adaptive neural network fuzzy inference system, extract array voltage, array current, array power, operating point slope and current discrete rate from an I-V curve, and then combine ambient temperature and irradiance to form 7 fault characteristic values as input data of the inference system, thereby realizing diagnosis of four faults of open-circuit faults, line faults, partial shading and aging faults; however, the accuracy requirement of the method on the detecting instrument is high, and meanwhile, the photovoltaic array needs to be disconnected and operated, so that certain loss is caused. The time sequence parameter method is to detect and classify faults by measuring voltage and current waveforms output by a photovoltaic array on line: li Guanghui et al utilize a semi-supervised machine learning method to realize the identification of the three types of normal state, open circuit fault and aging fault in the photovoltaic array; however, the method is limited by the complexity of the operation condition of the photovoltaic power generation end, and is difficult to realize. And the noise has a larger influence on the result.
DC-DC converters are an important structure in photovoltaic power generation systems. Direct current generated by the photovoltaic power generation end can be converted into direct current with different output voltages through the DC-DC converter according to different requirements. The DC-DC converter can also perform information transfer while the control of the output voltage is completed. In the actual control of the DC-DC converter, the control signal is mainly generated by the PWM technology, so that the control of the controllable elements in the converter is completed.
According to the power/data single carrier modulation technology in the prior art, the realization that for the switching working mode focusing on the power converter, a discrete transition state in the electric energy conversion process is utilized to load a data signal onto a discrete electric energy pulse so as to reflect the data signal on a switching ripple of the power input/output; however, the data modulation must use a degree of freedom different from that of the power modulation, and thus there is a limit to the choice of the data modulation method. In the information demodulation technology of the converter output end, wavelet transformation is more utilized to extract the information of the output signal at present: analyzing the zero crossing characteristic of wavelet transformation of the MPSK signal, and classifying the MPSK signal modulation type according to the change caused by signal phase jump on the wavelet transformation scale; however, this method is limited to fixed wavelet scales, and cannot achieve the selection of the optimal wavelet scale.
At present, methods for detecting faults of photovoltaic power generation modules mainly fall into two types. The method is used for directly detecting the photovoltaic power generation assembly (namely using a physical detection method such as physical thermal imaging) and calculating and analyzing electrical information such as current and voltage output by a photovoltaic power generation end (namely an energy metering algorithm, a characteristic calculation method, a time sequence parameter method and the like). However, the above method is limited by high cost (physical detection method), excessive dependence on accuracy of simulation model (energy meter algorithm), power generation loss caused by disconnection processing of photovoltaic module (characteristic calculation method), large noise influence and difficult realization (time sequence parameter method).
Disclosure of Invention
In order to solve the technical problems, the invention provides the photovoltaic power generation unit voltage regulation method and the system which are fused with fault information transmission, and the problems that the cost is too high, the fault information cannot be transmitted in time and the detection method is difficult to realize in the current stage of photovoltaic module fault detection are solved.
The technical scheme provided by the invention is as follows:
a photovoltaic power generation unit voltage regulation method integrating fault information transmission, the method comprising:
detecting abnormal conditions of a photovoltaic power generation end, and acquiring initial fault information of the abnormal conditions;
Switching carriers with corresponding frequencies based on the initial fault information, and transmitting carrier switching information;
In the transmission process, a voltage value output by an output end of the DC-DC converter is obtained, a difference value between the voltage value output by the output end of the DC-DC converter and a given value is made to be different from a carrier signal, and a PWM control signal for controlling a controllable element in the DC-DC converter is generated through a comparator;
And controlling a controllable element in the DC-DC converter through the PWM control signal, and demodulating according to the output voltage information of the output end to determine the fault information of the photovoltaic module.
Preferably, the detecting the abnormal condition of the photovoltaic power generation end includes:
The change rate of the energy generated by the photovoltaic power generation end is detected by detecting the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located.
Preferably, the acquiring the initial fault information of the abnormal situation includes:
Judging whether the photovoltaic power generation assembly has shielding faults or not according to the change rate of the ambient illumination intensity of the photovoltaic power generation assembly;
Judging the damage condition of the photovoltaic power generation assembly according to the change rate of energy generated by the photovoltaic power generation end;
when detecting that any change rate is equal to the change rate under the condition of no abnormality or does not exceed the preset range, the photovoltaic module does not have faults; when the difference value of the change rate and the change rate under the abnormal condition is detected to be out of a preset range, the photovoltaic power generation assembly fails, and corresponding information of the failure is used as initial failure information.
Preferably, the step of obtaining the voltage value output by the output end of the DC-DC converter includes:
when the carrier wave is different, the duty ratio of the PWM control signal generated by the comparator is changed, and the fluctuation range of the output voltage is influenced, the output voltage of the DC-DC converter in different fluctuation ranges is obtained.
Preferably, the demodulating according to the output voltage information of the output end, and determining the fault information of the photovoltaic module includes:
And respectively detecting the maximum value and the minimum value of the output voltage of the DC-DC converter by using a maximum value detection method according to different fluctuation ranges of the DC bus voltage to obtain peak value information of the output voltage of the DC-DC converter, and respectively comparing the peak value information with the peak value of the output voltage of the converter under the fault-free condition to identify fault information of the photovoltaic module.
A photovoltaic power generation unit voltage regulation system incorporating fault information transmission, the system comprising:
the detection module is used for detecting the abnormal condition of the photovoltaic power generation end and acquiring initial fault information of the abnormal condition;
the PWM signal generation module is used for switching the carrier wave with corresponding frequency based on the initial fault information and transmitting carrier wave switching information; in the transmission process, a voltage value output by an output end of the DC-DC converter is obtained, a difference value between the voltage value output by the output end of the DC-DC converter and a given value is made to be different from a carrier signal, and a PWM control signal for controlling a controllable element in the DC-DC converter is generated through a comparator;
and the information demodulation module is used for controlling the controllable element in the DC-DC converter through the PWM control signal, and then demodulating according to the output voltage information of the output end to determine the fault information of the photovoltaic module.
Preferably, the detection module includes:
the detection unit is used for detecting the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located and the change rate of energy generated by the photovoltaic power generation end;
The first judging unit is used for judging whether the photovoltaic power generation assembly has shielding faults or not according to the change rate of the ambient illumination intensity of the photovoltaic power generation assembly;
The second judging unit is used for judging the damage condition of the photovoltaic power generation assembly according to the change rate of energy generated by the photovoltaic power generation end;
The fault judging unit is used for detecting that the photovoltaic module does not have a fault when any change rate is equal to the change rate under the condition of no abnormality or does not exceed the preset range; when the difference value of the change rate and the change rate under the abnormal condition is detected to be out of a preset range, the photovoltaic power generation assembly fails, and corresponding information of the failure is used as initial failure information.
Preferably, the PWM signal generation module includes: the switching unit is used for switching the carrier wave with corresponding frequency according to the initial fault information;
And the acquisition unit is used for acquiring the output voltage of the DC-DC converter in different fluctuation ranges when the carrier wave is different to cause the change of the duty ratio of the PWM control signal generated by the comparator so as to influence the fluctuation range of the output voltage.
Preferably, the information demodulation module includes: the peak value detection unit is used for respectively detecting the maximum value and the minimum value of the output voltage of the DC-DC converter by utilizing a maximum value detection method according to the different fluctuation ranges of the DC bus voltage to obtain peak value information of the output voltage of the DC-DC converter;
And the determining unit is used for comparing the peak value information of the output voltage of the DC-DC converter with the peak value of the output voltage of the converter under the fault-free condition respectively so as to identify the fault information of the photovoltaic module.
Compared with the related art, the invention has the following beneficial effects:
According to the photovoltaic power generation unit voltage regulation method and system integrating fault information transmission, a time sequence parameter and energy information integration method is adopted, changes of parameters such as illumination intensity, current and voltage are detected at the photovoltaic power generation assembly end, and the fault information identification and transmission work is realized by combining relevant technologies of transmission and demodulation of converter information. The method can realize the transmission of fault information, and can realize the information transmission of the fault occurrence position for a large-scale photovoltaic power generation place, thereby being beneficial to the rapid maintenance of the faults of the photovoltaic module. Simple structure and easy control effect.
Compared with a physical detection method, an energy meter algorithm, characteristics and an algorithm and a time sequence parameter method, the method has the characteristics of low cost: the fault information extraction work is completed only by installing an illumination intensity detector and a current and voltage detection device at the photovoltaic power generation assembly end; the method has the characteristics of real-time: the transmission of fault information is completed by combining the generation principle of a DC-DC converter control signal; and meanwhile, the system also has the capability of rapidly demodulating fault information.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. Like elements or portions are generally identified by like reference numerals throughout the several figures. In the drawings, elements or portions thereof are not necessarily drawn to scale.
FIG. 1 is a flow chart of a voltage regulation method of a photovoltaic power generation unit fusing fault information transmission;
Fig. 2 is a schematic diagram of a PWM signal according to the present invention;
FIG. 3 is a schematic diagram of an information transmission principle provided by the present invention;
FIG. 4 is a flow chart of information demodulation provided by the present invention;
FIG. 5 is a flow chart of a method for detecting a maximum (small) value provided by the invention;
FIG. 6 is a flow chart of a peak detection method provided by the present invention;
FIG. 7 is a diagram of a photovoltaic module fault detection architecture provided by the present invention;
FIG. 8 is a block diagram of a dual photovoltaic fault detection provided by the present invention;
FIG. 9 is a simulation structure diagram of the fault detection of the single photovoltaic power generation assembly provided by the invention;
FIG. 10 is a graph of the output voltage of the system converter provided by the present invention;
FIG. 11 is a schematic diagram of fault information demodulation according to the present invention;
FIG. 12 is a simulation structure diagram of the fault detection of the double photovoltaic power generation assembly provided by the invention;
FIG. 13 is a system bus voltage arc diagram provided by the present invention;
fig. 14 is a schematic diagram of a demodulation result of fault information provided by the present invention.
Detailed Description
The following describes the embodiments of the present invention in further detail with reference to the drawings.
In order to specifically understand the technical scheme provided by the present invention, the following embodiments will describe and explain the technical scheme of the present invention in detail. It will be apparent that the embodiments of the invention provided are not limited to the specific details set forth in the skilled artisan. Preferred embodiments of the present invention are described in detail below, and the present invention may have other embodiments in addition to these descriptions.
The embodiment of the invention provides a photovoltaic power generation unit voltage regulation method integrating fault information transmission, which comprises the following steps:
S1, detecting abnormal conditions of a photovoltaic power generation end, and acquiring initial fault information of the abnormal conditions;
s2, switching carriers with corresponding frequencies based on initial fault information, and transmitting carrier switching information;
s3, in the transmission process, obtaining a voltage value output by an output end of the DC-DC converter, making a difference value between the voltage value output by the output end of the DC-DC converter and a given value and a carrier signal, and generating a PWM control signal for controlling a controllable element in the DC-DC converter through a comparator;
s4, controlling a controllable element in the DC-DC converter through the PWM control signal, and then demodulating according to the output voltage information of the output end to determine the fault information of the photovoltaic module.
In step S1, the detecting the abnormal condition of the photovoltaic power generation end includes:
The change rate of the energy generated by the photovoltaic power generation end is detected by detecting the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located.
The obtaining the initial fault information of the abnormal situation comprises the following steps:
Judging whether the photovoltaic power generation assembly has shielding faults or not according to the change rate of the ambient illumination intensity of the photovoltaic power generation assembly;
Judging the damage condition of the photovoltaic power generation assembly according to the change rate of energy generated by the photovoltaic power generation end;
when detecting that any change rate is equal to the change rate under the condition of no abnormality or does not exceed the preset range, the photovoltaic module does not have faults; when the difference value of the change rate and the change rate under the abnormal condition is detected to be out of a preset range, the photovoltaic power generation assembly fails, and corresponding information of the failure is used as initial failure information.
In step S3, the obtaining the voltage value output by the output end of the DC-DC converter includes:
when the carrier wave is different, the duty ratio of the PWM control signal generated by the comparator is changed, and the fluctuation range of the output voltage is influenced, the output voltage of the DC-DC converter in different fluctuation ranges is obtained.
In step S4, the demodulating according to the output voltage information of the output end, and determining the fault information of the photovoltaic module includes:
And respectively detecting the maximum value and the minimum value of the output voltage of the DC-DC converter by using a maximum value detection method according to different fluctuation ranges of the DC bus voltage to obtain peak value information of the output voltage of the DC-DC converter, and respectively comparing the peak value information with the peak value of the output voltage of the converter under the fault-free condition to identify fault information of the photovoltaic module.
Working principle:
For the photovoltaic power generation module, the failure problem of the photovoltaic module can cause serious conditions such as loss of photovoltaic power generation energy and fire disaster, whether the photovoltaic power generation module is a large photovoltaic power generation place (such as a plain, a mountain area and other places with little human smoke) or a simple photovoltaic power generation place such as a residential area. Therefore, timely and accurate transmission of fault information is an important standard for photovoltaic fault detection.
The first step of the invention needs to detect the abnormal condition of the photovoltaic power generation end, namely the primary acquisition work of fault information. In this process, it is necessary to detect the transformation condition of the photovoltaic power generation end (thereby detecting whether there is a fault such as shielding) and the change of the energy generated by the photovoltaic power generation end (thereby detecting whether there is a damage condition of the photovoltaic module).
The output voltage of the DC-DC converter is obtained under the fluctuation of the carrier wave, and the second stage of the invention is the transmission work of fault information. When the DC-DC converter is used for controlling the output voltage, a PWM control technique is required to control the full-control element IGBT in the converter to achieve the control effect. The PWM control schematic is shown in fig. 2. Namely, delta (delta is the difference between the voltage value output by the DC-DC converter and the given value in the constant voltage control of photovoltaic power generation) is different from the carrier signal, and a PWM control signal of 0-1 is obtained through a comparator. And demodulating the output voltage of the output end of the DC-DC converter to obtain corresponding fault information.
As shown in fig. 3, after the first step of fault information is obtained, carrier selection is performed in combination with the category of the corresponding fault information. The information transmission work is completed by means of different influences of different carriers on the PWM signals.
The third phase of the invention is the demodulation phase of the information, namely, corresponding fault information is obtained according to the related information of the output voltage of the output end of the DC-DC converter. For a DC-DC converter, the duty ratio of the "0-1" signal generated by the comparator is changed due to the different carriers in the PWM signal generation process, so that the fluctuation range of the output voltage is affected (under the influence of different carriers, although the fluctuation range of the output voltage of the converter is different, by the constant voltage control method used in the invention, the fluctuation range of the output voltage of the converter is within the allowable range in all cases).
As shown in fig. 4, the present invention needs to perform demodulation operation on the output voltage of the converter, so as to obtain corresponding fault information. The invention provides two methods for carrying out information demodulation operation on the output voltage of a converter. The principle is to detect whether the state of the photovoltaic power generation unit is a fault state according to the maximum value and the minimum value of the detected output voltage.
As shown in fig. 5, after the output voltage of the inverter is obtained, a maximum (small) value detection operation is performed, and the occurrence of a fault is determined by comparing the detected maximum (small) value of the output voltage at the present time with the maximum (small) value of the output voltage of the inverter in the case of no fault.
As shown in fig. 6, a peak detection method flow is shown. After the output voltage of the converter is obtained, respectively detecting the maximum value and the minimum value, so as to obtain the peak value information of the output voltage of the converter; the fault information is detected by comparing the peak value with the peak-to-peak value of the output voltage of the converter in the fault-free condition. Compared with the maximum (small) value detection method, the peak detection method can more accurately identify fault information (avoid the influence of the change of the fluctuation intermediate value of the bus voltage on the detection result after the fault information appears).
Based on the same inventive concept, the invention also provides a photovoltaic power generation unit voltage regulating system integrating fault information transmission, which comprises:
the detection module is used for detecting the abnormal condition of the photovoltaic power generation end and acquiring initial fault information of the abnormal condition;
the PWM signal generation module is used for switching the carrier wave with corresponding frequency based on the initial fault information and transmitting carrier wave switching information; in the transmission process, a voltage value output by an output end of the DC-DC converter is obtained, a difference value between the voltage value output by the output end of the DC-DC converter and a given value is made to be different from a carrier signal, and a PWM control signal for controlling a controllable element in the DC-DC converter is generated through a comparator;
and the information demodulation module is used for controlling the controllable element in the DC-DC converter through the PWM control signal, and then demodulating according to the output voltage information of the output end to determine the fault information of the photovoltaic module.
Wherein, the detection module includes:
the detection unit is used for detecting the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located and the change rate of energy generated by the photovoltaic power generation end;
The first judging unit is used for judging whether the photovoltaic power generation assembly has shielding faults or not according to the change rate of the ambient illumination intensity of the photovoltaic power generation assembly;
The second judging unit is used for judging the damage condition of the photovoltaic power generation assembly according to the change rate of energy generated by the photovoltaic power generation end;
The fault judging unit is used for detecting that the photovoltaic module does not have a fault when any change rate is equal to the change rate under the condition of no abnormality or does not exceed the preset range; when the difference value of the change rate and the change rate under the abnormal condition is detected to be out of a preset range, the photovoltaic power generation assembly fails, and corresponding information of the failure is used as initial failure information.
The PWM signal generation module includes:
the switching unit is used for switching the carrier wave with corresponding frequency according to the initial fault information;
And the acquisition unit is used for acquiring the output voltage of the DC-DC converter in different fluctuation ranges when the carrier wave is different to cause the change of the duty ratio of the PWM control signal generated by the comparator so as to influence the fluctuation range of the output voltage.
The information demodulation module includes:
The peak value detection unit is used for respectively detecting the maximum value and the minimum value of the output voltage of the DC-DC converter by utilizing a maximum value detection method according to the different fluctuation ranges of the DC bus voltage to obtain peak value information of the output voltage of the DC-DC converter;
And the determining unit is used for comparing the peak value information of the output voltage of the DC-DC converter with the peak value of the output voltage of the converter under the fault-free condition respectively so as to identify the fault information of the photovoltaic module.
The product structure specifically comprises: for a photovoltaic power generation module, it is necessary to detect a change in the intensity of ambient light in which the photovoltaic power generation module is located. The illumination intensity of the photovoltaic module changes obviously with time (day to night) from the whole day; however, if the light intensity of the photovoltaic power generation component is accurate to the second, the light intensity of the photovoltaic power generation component is equivalent to unchanged. Therefore, whether the shielding and other conditions occur can be judged by detecting the change rate of the illumination intensity of the surrounding environment where the photovoltaic module is located. When the photovoltaic module has the conditions of cracks, short circuit and open circuit, the information of fault occurrence can be obtained by detecting the change conditions of parameters such as output voltage, current and the like of the photovoltaic module.
The product structure of the system is shown in fig. 7. The invention takes a photovoltaic constant-voltage power generation control system as an example to demonstrate a fault information detection module; meanwhile, due to limitation of conditions (because the Matlab/Simulink platform does not have the function of changing parameters of the photovoltaic cell assembly in the simulation operation process, the influence of short circuit, cracks and the like of the photovoltaic power generation assembly is reflected by changing the illumination intensity of the photovoltaic power generation assembly), and the invention starts the transmission work of fault information by detecting the change rate of the illumination intensity of the photovoltaic power generation assembly.
As shown in fig. 7, it is first necessary to detect the rate of change of the illumination intensity at the photovoltaic power generation module. The change rate information is transmitted to the detection module, and the detection module makes judgment: when the detected change rate is equal to the change rate without special conditions (or within a specified range), the fact that the photovoltaic module has no fault condition is meant; when the difference between the detected change rate and the change rate without special conditions reaches the specified range, the failure of the photovoltaic power generation assembly is indicated.
After the detection module obtains the initial fault information of the photovoltaic power generation assembly, the carrier switching information is transmitted to the PWM signal generation module, so that the module uses a carrier with specific frequency to generate PWM signals for controlling controllable elements in the DC-DC converter, and corresponding output voltage of the DC-DC converter is generated. And obtaining fault information of the photovoltaic module through an information demodulation module according to the obtained output voltage of the DC-DC converter.
The method provided by the invention has good performance in the detection work of double (multiple) photovoltaic fault alarm and fault position information. In the photovoltaic power generation system shown in fig. 8, two photovoltaic power generation modules are connected in parallel to a direct current bus to supply power to a load. When the photovoltaic power generation module 1 and the photovoltaic power generation module 2 have no special condition, the same carrier frequency f is used for generating PWM signals. When the photovoltaic power generation assembly 1 fails, the PWM signal generation module 1 is enabled to use the carrier frequency f 1; similarly, when the photovoltaic power generation module 2 fails, the PWM signal generation module 2 is caused to use the carrier frequency f 2. At different carrier frequencies, the voltage of the dc bus is affected differently, i.e. the fluctuation range is different.
Based on the above, the invention demodulates the fault information by using the maximum value detection method according to the different fluctuation ranges of the DC bus voltage: firstly, the fluctuation range of the direct current bus voltage when the photovoltaic power generation assembly 1 and the photovoltaic power generation assembly 2 have no faults is compared with the fluctuation range under the fault-free condition when the fault condition occurs, and then fault information is obtained. And the fluctuation range is acquired by adopting a maximum value detection method. I.e. by measuring the maximum and minimum values of the output voltage at the same point in time, and taking the difference.
Example 1:
In the embodiment 1 of the invention, simulation verification is carried out on a Matlab/Simulink (version 2018 b) platform. According to the invention, two verification experiments are carried out, namely, fault alarm of the photovoltaic power generation module in Shan Guangfu power generation mode and fault alarm of the photovoltaic power generation module in double photovoltaics.
As shown in fig. 9, a simulation structure diagram of experiment one is shown. The basic parameters of the photovoltaic module are as follows: 92 rows and 60 columns; basic parameters in DC-DC converters: the capacitance C is 68×10 -5 F, the inductance L is 1×10 -3 H, and the resistance R is 600Ω. The output end of the photovoltaic cell is connected with the RC module to be 68 multiplied by 10 -5 F and 0.0001 omega. The photovoltaic cell is herein brought to a temperature environment of 25 °. The experiment requires simulating the fault condition of the photovoltaic power generation module by detecting the conversion rate of the illumination intensity. In the absence of fault conditions, the illumination intensity is 1500 (+ -50) Lux; in the event of a fault, the illumination intensity is 1200 (+ -50) Lux. In the converter control module, when no fault exists, the carrier frequency of the PWM signal generating module in the converter control module is 10000Hz; when in a fault state, the carrier frequency of the PWM signal generating module in the converter control module is 5000Hz. When the change rate of the illumination intensity received by the photovoltaic power generation end exceeds a specified range, the fault information is transmitted to the converter control module, and the frequency of the PWM signal carrier wave in the module is switched.
In experiment one, the system was made to "fail" at 1.5-1.7s, i.e. the intensity of illumination to which the photovoltaic cells were subjected was switched at 1.5-1.7 s.
As shown in fig. 10, the method for switching the carrier frequency of the PWM generation module according to the parameters of the photovoltaic generation module has no influence on the stability of the system, and the bus voltage of the system is stabilized at 1200V. The system can keep the stability of the output voltage of the converter under the action of the constant voltage control method. Fig. 11 shows the demodulation result of the fault information, wherein "0" represents no fault condition, and "1" represents the fault condition of the photovoltaic terminal.
As shown in fig. 12, a simulation structure diagram of experiment two is shown. And in the experiment II, two photovoltaic power generation assemblies are connected in parallel to supply power to the load module. The basic parameters of the photovoltaic power generation module 1 and the photovoltaic power generation module 2 are the same as those of the experiment one. When the photovoltaic power generation modules 1 and 2 have no faults, the PWM signal generation module uses a carrier wave with the frequency of 5000 Hz; when the photovoltaic cell end in the photovoltaic power generation module 1 fails, the carrier frequency adopted by the PWM generation module in the photovoltaic power generation module 1 is switched from 5000Hz to 10000Hz; when the photovoltaic cell end in the photovoltaic power generation module 2 fails, the carrier frequency adopted by the PWM generation module in the photovoltaic power generation module 2 is switched from 5000Hz to 2500Hz. And judging whether the fault occurs or not and the occurrence position of the fault through analysis of the state presented by the information demodulation module to the bus voltage.
In the second experiment, we put the photovoltaic power module 1 in a fault state at 1.5-1.7 s; the photovoltaic power generation module 1 is in a fault state at 1.9-2.3 s.
As shown in fig. 13, the method for switching the carrier frequency of the PWM generation module according to the parameters of the photovoltaic generation module has no influence on the stability of the system, and the bus voltage of the system is stabilized at 1200V. The system can keep the stability of the output voltage of the converter under the action of the constant voltage control method. Fig. 14 shows the result of demodulation of the fault information, wherein "2" represents a no fault condition, "1" represents a fault condition of the photovoltaic power generation module 1, and "3" represents a fault condition of the photovoltaic power generation module 2. Unlike experiment one, the fault conditions faced by experiment two become more, and the detector (the detector used in the invention measures the most value of the measured signal in a certain time interval) needs to be refreshed for detecting the fault information. The time interval used in this experiment was 0.1s. In fig. 14, therefore, a case where the fault information is zeroed out a plurality of times (i.e., a signal appears as a vertical streak) occurs. The situation does not affect the Display of the fault detection information (the last fault information is displayed through a Display module in the Simulink, and the situation of intermediate zero setting does not affect the final information Display).
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention, and are intended to be included within the scope of the appended claims and description.
Claims (5)
1. The utility model provides a photovoltaic power generation unit voltage regulation method of fusion trouble information transmission which characterized in that, the method includes:
detecting abnormal conditions of a photovoltaic power generation end, and acquiring initial fault information of the abnormal conditions;
Switching carriers with corresponding frequencies based on the initial fault information, and transmitting carrier switching information;
After the first step of fault information is obtained, selecting carriers by combining the types of the corresponding fault information; the information transmission work is completed by means of different influences of different carriers on PWM signals;
In the transmission process, a voltage value output by an output end of the DC-DC converter is obtained, a difference value between the voltage value output by the output end of the DC-DC converter and a given value is made to be different from a carrier signal, and a PWM control signal for controlling a controllable element in the DC-DC converter is generated through a comparator;
the controllable elements in the DC-DC converter are controlled through the PWM control signals, and then demodulation is carried out according to the output voltage information of the output end, so that the fault information of the photovoltaic module is determined;
demodulating according to the output voltage information of the output end, and determining the fault information of the photovoltaic module comprises:
Detecting the maximum value or the minimum value of the output voltage of the DC-DC converter by utilizing a maximum value detection method according to the fluctuation range of the DC bus voltage to obtain peak value information of the output voltage of the DC-DC converter, and comparing the peak value information with the peak value of the output voltage of the DC-DC converter under the fault-free condition to identify fault information of the photovoltaic module; or after obtaining the output voltage of the DC-DC converter, respectively carrying out maximum value and minimum value detection, and comparing the maximum value and the minimum value of the output voltage at the current moment with the maximum value and the minimum value of the output voltage of the DC-DC converter under the condition of no fault so as to judge the occurrence of the fault;
The step of obtaining the voltage value output by the output end of the DC-DC converter comprises the following steps:
when the carrier wave is different, the duty ratio of the PWM control signal generated by the comparator is changed, and the fluctuation range of the output voltage is influenced, the output voltage of the DC-DC converter in different fluctuation ranges is obtained.
2. The method for regulating voltage of a photovoltaic power generation unit fused with fault information transmission according to claim 1, wherein the detecting of the abnormal condition of the photovoltaic power generation end comprises:
The change rate of the energy generated by the photovoltaic power generation end is detected by detecting the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located.
3. The method for regulating voltage of a photovoltaic power generation unit in combination with fault information transmission according to claim 1, wherein the obtaining initial fault information of occurrence of abnormal conditions comprises:
Judging whether the photovoltaic power generation assembly has shielding faults or not according to the change rate of the ambient illumination intensity of the photovoltaic power generation assembly;
Judging the damage condition of the photovoltaic power generation assembly according to the change rate of energy generated by the photovoltaic power generation end;
when detecting that any change rate is equal to the change rate under the condition of no abnormality or does not exceed the preset range, the photovoltaic module does not have faults; when the difference value of the change rate and the change rate under the abnormal condition is detected to be out of a preset range, the photovoltaic power generation assembly fails, and corresponding information of the failure is used as initial failure information.
4. A photovoltaic power generation unit voltage regulation system incorporating fault information transmission, the system comprising:
the detection module is used for detecting the abnormal condition of the photovoltaic power generation end and acquiring initial fault information of the abnormal condition;
The PWM signal generation module is used for switching the carrier wave with corresponding frequency based on the initial fault information and transmitting carrier wave switching information;
After the first step of fault information is obtained, selecting carriers by combining the types of the corresponding fault information; the information transmission work is completed by means of different influences of different carriers on PWM signals;
In the transmission process, a voltage value output by an output end of the DC-DC converter is obtained, a difference value between the voltage value output by the output end of the DC-DC converter and a given value is made to be different from a carrier signal, and a PWM control signal for controlling a controllable element in the DC-DC converter is generated through a comparator;
The information demodulation module is used for controlling the controllable elements in the DC-DC converter through the PWM control signals, and then demodulating according to the output voltage information of the output end to determine the fault information of the photovoltaic module;
The information demodulation module includes:
The peak value detection unit is used for respectively detecting the maximum value or the minimum value of the output voltage of the DC-DC converter by utilizing a maximum value detection method according to the different fluctuation ranges of the DC bus voltage to obtain peak value information of the output voltage of the DC-DC converter;
the determining unit is used for comparing the peak value information of the output voltage of the DC-DC converter with the peak value of the output voltage of the DC-DC converter under the fault-free condition respectively so as to identify the fault information of the photovoltaic module;
The PWM signal generation module includes:
the switching unit is used for switching the carrier wave with corresponding frequency according to the initial fault information;
And the acquisition unit is used for acquiring the output voltage of the DC-DC converter in different fluctuation ranges when the carrier wave is different to cause the change of the duty ratio of the PWM control signal generated by the comparator so as to influence the fluctuation range of the output voltage.
5. The system of claim 4, wherein the detection module comprises:
the detection unit is used for detecting the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located and the change rate of energy generated by the photovoltaic power generation end;
The first judging unit is used for judging whether the photovoltaic power generation assembly has shielding faults or not according to the change rate of the ambient illumination intensity of the photovoltaic power generation assembly;
The second judging unit is used for judging the damage condition of the photovoltaic power generation assembly according to the change rate of energy generated by the photovoltaic power generation end;
The fault judging unit is used for detecting that the photovoltaic module does not have a fault when any change rate is equal to the change rate under the condition of no abnormality or does not exceed the preset range; when the difference value of the change rate and the change rate under the abnormal condition is detected to be out of a preset range, the photovoltaic power generation assembly fails, and corresponding information of the failure is used as initial failure information.
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