CN114389541A - 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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Abstract
The invention discloses a photovoltaic power generation unit voltage regulation method and system integrating fault information transmission, which comprises the steps of detecting abnormal conditions of a photovoltaic power generation end and acquiring initial fault information of the abnormal conditions; switching the carrier wave of the corresponding frequency based on the initial fault information, and transmitting the carrier wave switching information; in the transmission process, acquiring a voltage value output by an output end of the DC-DC converter, subtracting a difference value between the voltage value output by the output end of the DC-DC converter and a given value from a carrier signal, and generating a PWM control signal for controlling a controllable element in the DC-DC converter through a comparator; and controlling a controllable element in the DC-DC converter through the PWM control signal, and demodulating according to output voltage information of an output end to determine fault information of the photovoltaic module. According to the scheme, when the photovoltaic module is abnormal, the information of the fault can be obtained by detecting the change condition of parameters such as the output voltage and the 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 field of photovoltaic power generation, the safe operation of a photovoltaic array is more and more emphasized. 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 influenced 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 can be caused inevitably. With the large-scale deployment of the photovoltaic power generation components, the problem of faults can make the power generation capacity and safety of the whole power generation system greatly challenged. The problem of faults can be found in time, so that the reasonable solution of the corresponding faults becomes one of the research focuses of photovoltaic power generation at the present stage.
At the present stage, photovoltaic fault detection is mainly divided into a physical detection method, an energy calculation method, a characteristic calculation method, a time sequence parameter method and the like. The fault detection of the photovoltaic power generation module is completed by physical means such as thermal imaging and by analyzing the physical characteristics of the photovoltaic power generation module: benato G.A.D.R. et al, which utilizes an unmanned aerial vehicle to take an electroluminescence image of a photovoltaic array under a high irradiance condition, identify faults related to power loss through image information; although the method can complete the fault detection of the photovoltaic power generation panel without contacting the photovoltaic panel, the cost of the method is too high, and the detection result is greatly influenced by environmental factors. Calculating theoretical output energy according to the setting of the parameters of the photovoltaic panel to obtain a difference value between the theoretical output energy and actual output energy, and using the difference value as a basis for fault diagnosis: dhimish M. et al substitute power loss and voltage loss into a cubic polynomial function to obtain a fault limit curve, and then combine 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 and current output by the photovoltaic module and combining the parameter setting of the system: the Ganluo et al provides a fault diagnosis method based on an adaptive neural network fuzzy inference system, which extracts array voltage, array current, array power, working point slope and current dispersion rate from an I-V curve, and combines ambient temperature and irradiance to form 7 fault characteristic values as input data of the inference system, thereby realizing the diagnosis of four faults, namely open-circuit fault, line-to-line fault, partial shading fault and aging fault; however, the accuracy requirement of such a method for the detection instrument is relatively high, and meanwhile, the photovoltaic array needs to be disconnected from operation, which causes a certain loss. The time sequence parameter method is to detect and classify faults by measuring voltage and current waveforms output by the photovoltaic array on line: li Shuang et al uses a semi-supervised machine learning method to realize the identification of a normal state, an open-circuit fault and an aging fault in a photovoltaic array; however, the method is limited by the complexity of the operation condition of the photovoltaic power generation end, and is difficult to implement. While noise has a large impact on the result.
DC-DC converters are important structures in photovoltaic power generation systems. Direct current generated by the photovoltaic power generation end can be converted into direct current with different output voltages according to different requirements through the DC-DC converter. The DC-DC converter can also transmit information while finishing the control of the output voltage. In the actual control of the DC-DC converter, the PWM technique is mainly used to generate the control signal to control the controllable elements in the converter.
In the prior art, according to a power/data single carrier modulation technology, a switching working mode focusing on a power converter is realized, and a data signal is loaded onto a discrete electric energy pulse by utilizing a discrete transition state in an electric energy conversion process so as to be reflected on a power input/output switching ripple; however, data modulation must use a different degree of freedom from power modulation, and therefore, there is a certain restriction on the selection of a data modulation method. In the information demodulation technology at the output end of the converter, wavelet transformation is more utilized at present to extract the information of the output signal: the zero-crossing characteristics of wavelet transformation of the MPSK signals are analyzed, and the classification of the modulation types of the MPSK signals is realized according to the change of signal phase jump on the wavelet transformation scale; however, this method is limited to a fixed wavelet scale, and the selection of the optimal wavelet scale cannot be achieved.
At present, methods for detecting faults of photovoltaic power generation modules are mainly divided into two types. One is to directly detect the photovoltaic power generation module (i.e. using physical detection methods such as physical thermal imaging), and the other is to calculate and analyze electrical information such as current and voltage output by the photovoltaic power generation end (i.e. energy meter algorithm, characteristic calculation method, time sequence parameter method, etc.). However, the above methods are limited by high cost (physical detection method), excessive dependence on accuracy of the simulation model (energy calculation method), power generation loss caused by disconnection processing of the photovoltaic module (characteristic calculation method), large noise influence and difficult realization (timing parameter method).
Disclosure of Invention
In order to solve the technical problems, the invention provides a photovoltaic power generation unit voltage regulation method and system integrating fault information transmission, and solves 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 fault detection of a photovoltaic module at the present stage.
The technical scheme provided by the invention is as follows:
a voltage regulation method for a photovoltaic power generation unit fusing fault information transmission comprises the following steps:
detecting the abnormal condition of the photovoltaic power generation end, and acquiring initial fault information of the abnormal condition;
switching the carrier wave of the corresponding frequency based on the initial fault information, and transmitting the carrier wave switching information;
in the transmission process, acquiring a voltage value output by an output end of the DC-DC converter, subtracting a difference value between the voltage value output by the output end of the DC-DC converter and a given value from a carrier signal, and generating a PWM control signal for controlling a controllable element in the DC-DC converter through a comparator;
and controlling a controllable element in the DC-DC converter through the PWM control signal, and demodulating according to output voltage information of an output end to determine fault information of the photovoltaic module.
Preferably, the detecting the abnormal condition of the photovoltaic power generation terminal includes:
the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located and the change rate of the energy generated by the photovoltaic power generation end are detected.
Preferably, the acquiring initial fault information of the abnormal condition includes:
judging whether the photovoltaic power generation assembly has a shielding fault or not according to the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located;
judging the damage condition of the photovoltaic power generation assembly according to the change rate of the energy generated by the photovoltaic power generation end;
when any change rate is detected to be equal to the change rate under the abnormal condition or not exceed the preset range, the photovoltaic module does not break down; and when the difference value between the change rate and the change rate under the abnormal condition is detected to be out of the preset range, the photovoltaic power generation assembly breaks down, and corresponding information of the broken down is used as initial fault information.
Preferably, the obtaining the voltage value output by the output end of the DC-DC converter includes:
when the duty ratio of the PWM control signal generated by the comparator is changed due to different carriers, and the fluctuation range of the output voltage is further 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 terminal and the determining the fault information of the photovoltaic module include:
according to the different fluctuation ranges of the direct current bus voltage, maximum value and minimum value detection is carried out on the output voltage of the DC-DC converter respectively by utilizing a maximum value detection method to obtain peak value information of the output voltage of the DC-DC converter, and the peak value information is compared with the peak value of the output voltage of the converter under the condition of no fault respectively to identify the fault information of the photovoltaic module.
A photovoltaic power generation unit voltage regulation system that fuses transmission of fault information, the system includes:
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 the carrier wave switching information; in the transmission process, acquiring a voltage value output by an output end of the DC-DC converter, subtracting a difference value between the voltage value output by the output end of the DC-DC converter and a given value from a carrier signal, and generating a PWM control signal for controlling a controllable element in the DC-DC converter 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, demodulating according to the output voltage information of the output end and determining 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 the energy generated by the photovoltaic power generation end;
the first judgment unit is used for judging whether the photovoltaic power generation assembly has a shielding fault or not according to the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located;
the second judging unit is used for judging the damage condition of the photovoltaic power generation assembly according to the change rate of the energy generated by the photovoltaic power generation end;
the fault judging unit is used for judging that the photovoltaic module has no fault when any change rate is equal to the change rate under the abnormal condition or does not exceed the preset range; and when the difference value between the change rate and the change rate under the abnormal condition is detected to be out of the preset range, the photovoltaic power generation assembly breaks down, and corresponding information of the broken down is used as initial fault information.
Preferably, the PWM signal generation module includes: the switching unit is used for switching the carrier wave of the 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 fluctuation range of the output voltage is influenced by the change of the duty ratio of the PWM control signal generated by the comparator due to different carriers.
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 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 condition of no fault 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 a photovoltaic power generation assembly end, and the fault information is identified and transmitted by combining with the related technology of transmission and demodulation of converter information. The method can realize the transmission of fault information, and meanwhile, for large photovoltaic power generation places, the information transmission of fault occurrence positions can be realized, thereby being beneficial to the rapid maintenance of the faults of the photovoltaic modules. Simple structure and easy realization of control effect.
Compared with a physical detection method, an energy calculation method, a characteristic and algorithm and a time sequence parameter method, the method provided by the invention has the characteristics of low cost: the extraction work of fault information is completed only by installing an illumination intensity detector and a current and voltage detection device at the end of the photovoltaic power generation assembly; the method has the characteristics of real-time property: the transmission of the fault information is completed by combining the generation principle of the control signal of the DC-DC converter; and meanwhile, the capability of quickly demodulating fault information is also provided.
Drawings
In order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description of the invention or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.
Fig. 1 is a flow chart of a voltage regulating method for a photovoltaic power generation unit integrating fault information transmission provided by the invention;
FIG. 2 is a schematic diagram of the PWM signal principle provided by the present invention;
FIG. 3 is a schematic diagram of the information transfer 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 maximum (small) value detection method provided by the present 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 for fault detection of a single photovoltaic power generation assembly provided by the present invention;
FIG. 10 is an arc plot of the output voltage of the system converter provided by the present invention;
FIG. 11 is a schematic diagram of the demodulation of fault information provided by the present invention;
FIG. 12 is a simulation structure diagram of the fault detection of the dual photovoltaic power generation assembly provided by the present 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 the fault information provided by the present invention.
Detailed Description
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
In order to specifically understand the technical solutions provided by the present invention, the technical solutions of the present invention will be described and illustrated in detail in the following examples. It is apparent that the embodiments provided by the present invention are not limited to the specific details familiar to those skilled in the art. The following detailed description of the preferred embodiments of the invention is intended to provide further embodiments of the invention in addition to those described herein.
The specific embodiment of the invention provides a photovoltaic power generation unit voltage regulation method integrating fault information transmission, which comprises the following steps:
s1, detecting the abnormal condition of the photovoltaic power generation end, and acquiring initial fault information of the abnormal condition;
s2 switching the carrier wave of the corresponding frequency based on the initial fault information, and transmitting the carrier wave switching information;
s3, in the transmission process, acquiring the voltage value output by the output end of the DC-DC converter, making a difference between the 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, 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 to determine the fault information of the photovoltaic module.
In step S1, the detecting an abnormal condition of the photovoltaic power generation terminal includes:
the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located and the change rate of the energy generated by the photovoltaic power generation end are detected.
The acquiring of the initial fault information of the abnormal condition includes:
judging whether the photovoltaic power generation assembly has a shielding fault or not according to the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located;
judging the damage condition of the photovoltaic power generation assembly according to the change rate of the energy generated by the photovoltaic power generation end;
when any change rate is detected to be equal to the change rate under the abnormal condition or not exceed the preset range, the photovoltaic module does not break down; and when the difference value between the change rate and the change rate under the abnormal condition is detected to be out of the preset range, the photovoltaic power generation assembly breaks down, and corresponding information of the broken down is used as initial fault information.
In step S3, the obtaining the voltage value output by the output terminal of the DC-DC converter includes:
when the duty ratio of the PWM control signal generated by the comparator is changed due to different carriers, and the fluctuation range of the output voltage is further 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 terminal to determine the fault information of the photovoltaic module includes:
according to the different fluctuation ranges of the direct current bus voltage, maximum value and minimum value detection is carried out on the output voltage of the DC-DC converter respectively by utilizing a maximum value detection method to obtain peak value information of the output voltage of the DC-DC converter, and the peak value information is compared with the peak value of the output voltage of the converter under the condition of no fault respectively to identify the fault information of the photovoltaic module.
The working principle is as follows:
for a photovoltaic power generation assembly, in a large photovoltaic power generation place (for example, a region with rare people such as a plain and a mountain region) or a simple photovoltaic power generation place such as a residential area, the failure problem of the photovoltaic power generation assembly may cause serious conditions such as loss of photovoltaic power generation energy and fire. Therefore, timely and accurate transmission of fault information is an important standard for photovoltaic fault detection.
The first step of the method needs to detect the abnormal condition of the photovoltaic power generation terminal, namely the primary acquisition work of the fault information. In the process, the conversion condition of the light received by the photovoltaic power generation end (so as to detect the existence of faults such as shielding) and the change of the energy generated by the photovoltaic power generation end (so as to detect the existence of damage of the photovoltaic module) need to be detected.
The output voltage of the DC-DC converter under the fluctuation of the carrier wave is obtained, and the second stage of the invention is the transmission work of the fault information. When the DC-DC converter realizes the control of the output voltage, the control effect of a full control element, namely IGBT, in the converter is required to be realized through a PWM control technology. The PWM control scheme is shown in fig. 2. That is, Δ (for example, in the photovoltaic power generation constant voltage control, Δ is a difference between a voltage value output through the DC-DC converter and a given value) is subtracted from the carrier signal, and a PWM control signal of "0 to 1" is obtained through the 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 failure information is obtained, the carrier is selected according to the category of the corresponding failure information. The different carrier waves have different influences on the PWM signals, so that the information transmission work is completed.
The third stage of the invention is the information demodulation stage, 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 a '0-1' signal generated by a comparator is changed due to different carriers in the PWM signal generation process, and further the fluctuation range of the output voltage is influenced (under the influence of different carriers, although the fluctuation ranges of the output voltage of the converter are different, the fluctuation range of the output voltage of the converter is in an allowable range in all cases through the constant voltage control method used by the invention).
As shown in fig. 4, the present invention needs to perform information demodulation operation on the output voltage of the converter, so as to obtain corresponding fault information. The invention provides two methods for demodulating the output voltage of the converter. The principle is that whether the state of the photovoltaic power generation unit is a fault state or not is detected 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 converter is obtained, the 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 converter in the case of no fault.
Fig. 6 shows a flow of peak detection method. After the output voltage of the converter is obtained, respectively detecting the maximum value and the minimum value, thereby obtaining the peak value information of the output voltage of the converter; and comparing the peak value with the peak value of the output voltage of the converter under the condition of no fault to detect fault information. Compared with a maximum (small) value detection method, the peak value detection method can more accurately identify fault information (the influence of the change of the fluctuation intermediate value of the bus voltage on the detection result after the fault information appears is avoided).
Based on the same invention concept, the invention also provides a photovoltaic power generation unit voltage regulation 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 the carrier wave switching information; in the transmission process, acquiring a voltage value output by an output end of the DC-DC converter, subtracting a difference value between the voltage value output by the output end of the DC-DC converter and a given value from a carrier signal, and generating a PWM control signal for controlling a controllable element in the DC-DC converter 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, demodulating according to the output voltage information of the output end and determining the fault information of the photovoltaic module.
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 the energy generated by the photovoltaic power generation end;
the first judgment unit is used for judging whether the photovoltaic power generation assembly has a shielding fault or not according to the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located;
the second judging unit is used for judging the damage condition of the photovoltaic power generation assembly according to the change rate of the energy generated by the photovoltaic power generation end;
the fault judging unit is used for judging that the photovoltaic module has no fault when any change rate is equal to the change rate under the abnormal condition or does not exceed the preset range; and when the difference value between the change rate and the change rate under the abnormal condition is detected to be out of the preset range, the photovoltaic power generation assembly breaks down, and corresponding information of the broken down is used as initial fault information.
The PWM signal generation module includes:
the switching unit is used for switching the carrier wave of the 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 fluctuation range of the output voltage is influenced by the change of the duty ratio of the PWM control signal generated by the comparator due to different carriers.
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 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 condition of no fault so as to identify the fault information of the photovoltaic module.
The product structure specifically includes: for a photovoltaic power generation module, the change of the illumination intensity of the environment where the photovoltaic power generation assembly is located needs to be detected. The illumination intensity of the photovoltaic module changes obviously with the time from the whole day perspective (day to night); however, if the accuracy is up to a second, the intensity of the light received by the photovoltaic power generation assembly is equivalent to no change. Therefore, the occurrence of the shielding and the like 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 cracks, short circuit, open circuit and other conditions, 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 the limitation of conditions (because the Matlab/Simulink platform does not have the function of changing the parameters of the photovoltaic cell module in the simulation operation process, the influences of short circuit, cracks and the like of the photovoltaic power generation module are reflected by changing the illumination intensity of the photovoltaic power generation module), the method starts the transmission work of fault information by detecting the change rate of the illumination intensity of the photovoltaic power generation module.
As shown in fig. 7, the rate of change of the light intensity needs to be detected at the photovoltaic power generation module first. And transmitting the change rate information to a detection module, and judging by the detection module: when the detected change rate is equal to (or within a specified range of) the change rate without special cases, it means that the photovoltaic module has not failed; when the difference value between the detected change rate and the change rate without special condition is out of the specified range, the photovoltaic power generation assembly is indicated to be in fault.
And 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 generates a PWM signal for controlling a controllable element in the DC-DC converter by using a carrier with a specific frequency, and generates corresponding output voltage of the DC-DC converter. And obtaining the 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. As shown in fig. 8, in the photovoltaic power generation system, two photovoltaic power generation modules are connected in parallel to a dc bus to provide electric energy for a load. When there is no special condition, the photovoltaic power generation module 1 and the photovoltaic power generation module 2 use the same carrier frequency f to participate in the generation of the PWM signal. When the photovoltaic power generation assembly 1 fails, the PWM signal generation module 1 uses the carrier frequency f1(ii) a Similarly, when the photovoltaic power generation module 2 fails, the PWM signal generation module 2 uses the carrier frequency f2. At different carrier frequencies, the voltage of the dc bus is affected differently, i.e. the fluctuation range will be different.
Based on the above, the invention demodulates the fault information by using the most value detection method according to the different fluctuation ranges of the DC bus voltage: firstly, for the fluctuation range of the direct current bus voltage under the condition that both the photovoltaic power generation assembly 1 and the photovoltaic power generation assembly 2 have no fault, preparing a detection module, and comparing the fluctuation range with the fluctuation range under the condition that no fault exists when the fault occurs so as to obtain fault information. And the maximum value detection method is adopted for obtaining the fluctuation range. Namely, the voltage difference is obtained by measuring the maximum value and the minimum value of the output voltage at the same time point and performing difference.
Example 1:
in the embodiment 1 of the invention, simulation verification is carried out on a Matlab/Simulink (version 2018b) platform. According to the invention, two verification experiments are carried out, namely the failure alarm of the photovoltaic power generation module under the single photovoltaic power generation mode and the failure alarm of the photovoltaic power generation module under the double photovoltaic power generation mode.
As shown in fig. 9, a simulation structure diagram of experiment one is shown. The photovoltaic module comprises the following basic parameters: 92 rows, 60 columns; basic parameters in the DC-DC converter: the capacitance C is 68 x 10-5F, inductance L is 1 x 10-3H, and the resistance R is 600 omega. The output end of the photovoltaic cell is connected with an RC module of 68 multiplied by 10-5F and 0.0001 Ω. The photovoltaic cell is subjected to a temperature environment of 25 deg. The experiment needs to simulate the fault condition of the photovoltaic power generation module by detecting the conversion rate of the illumination intensity. In the case of no fault, the illumination intensity is 1500 (+ -50) Lux; in the case of failure, the illumination intensity was 1200 (+ -50) Lux. In the converter control module, when no fault exists, the carrier frequency of a PWM signal generation module in the converter control module is 10000 Hz; when in a fault state, the carrier frequency of the PWM signal generation module in the converter control module is 5000 Hz. When the change rate of the illumination intensity of the photovoltaic power generation end is detected to exceed 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 the first experiment, the system is enabled to have a 'fault condition' within 1.5-1.7s, namely, the illumination intensity of the photovoltaic cell is switched within 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 photovoltaic power generation component parameters 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 used by the invention. Fig. 11 shows the demodulation result of the fault information, where "0" represents a no-fault condition and "1" represents a fault condition at the photovoltaic terminal.
As shown in fig. 12, a simulation structure of experiment two is shown. And in the second experiment, 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 first experiment. When the photovoltaic power generation modules 1 and 2 are free of faults, the PWM signal generation module uses a carrier wave with the frequency of 5000 Hz; when a photovoltaic battery end in the photovoltaic power generation module 1 breaks down, the carrier frequency adopted by a PWM generation module in the photovoltaic power generation module 1 is switched from 5000Hz to 10000 Hz; when a photovoltaic battery end in the photovoltaic power generation module 2 breaks down, the carrier frequency adopted by the PWM generation module in the photovoltaic power generation module 2 is switched from 5000Hz to 2500 Hz. Whether the fault occurs or not and the occurrence position of the fault are judged through the analysis of the state presented by the bus voltage by the information demodulation module.
In experiment two, the photovoltaic power generation module 1 is in a fault state within 1.5-1.7 s; the photovoltaic power generation module 1 is in a fault state for 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 photovoltaic power generation component parameters 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 used by the invention. Fig. 14 is a demodulation result of the failure information, in which "2" represents a no-failure condition, "1" represents a failure condition of the photovoltaic power generation module 1, and "3" represents a failure condition of the photovoltaic power generation module 2. Different from the first experiment, the second experiment has more fault conditions, and the most significant detector (the most significant detector used in the invention measures the most significant of the measured signal within a certain time interval) needs to be refreshed after a certain time interval to detect fault information. The time interval used in this experiment was 0.1 s. In fig. 14, therefore, there are a number of instances where the fault information is zeroed (i.e., the signal is rippled). This does not affect the presentation of the fault detection information (the last fault information is presented through the Display module in Simulink, and the intermediate zeroing does not affect the final information presentation).
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.
Claims (9)
1. A voltage regulation method for a photovoltaic power generation unit integrating fault information transmission is characterized by comprising the following steps:
detecting the abnormal condition of the photovoltaic power generation end, and acquiring initial fault information of the abnormal condition;
switching the carrier wave of the corresponding frequency based on the initial fault information, and transmitting the carrier wave switching information;
in the transmission process, acquiring a voltage value output by an output end of the DC-DC converter, subtracting a difference value between the voltage value output by the output end of the DC-DC converter and a given value from a carrier signal, and generating a PWM control signal for controlling a controllable element in the DC-DC converter through a comparator;
and controlling a controllable element in the DC-DC converter through the PWM control signal, and demodulating according to output voltage information of an output end to determine fault information of the photovoltaic module.
2. The method for regulating the voltage of the photovoltaic power generation unit fusing the fault information transmission according to claim 1, wherein the detecting the abnormal condition of the photovoltaic power generation terminal comprises:
the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located and the change rate of the energy generated by the photovoltaic power generation end are detected.
3. The method for regulating the voltage of the photovoltaic power generation unit by fusing fault information transmission according to claim 1, wherein the acquiring of the initial fault information of the abnormal condition comprises:
judging whether the photovoltaic power generation assembly has a shielding fault or not according to the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located;
judging the damage condition of the photovoltaic power generation assembly according to the change rate of the energy generated by the photovoltaic power generation end;
when any change rate is detected to be equal to the change rate under the abnormal condition or not exceed the preset range, the photovoltaic module does not break down; and when the difference value between the change rate and the change rate under the abnormal condition is detected to be out of the preset range, the photovoltaic power generation assembly breaks down, and corresponding information of the broken down is used as initial fault information.
4. The method for regulating the voltage of the photovoltaic power generation unit integrating fault information transmission according to claim 1, wherein the step of obtaining the voltage value output by the output end of the DC-DC converter comprises the following steps:
when the duty ratio of the PWM control signal generated by the comparator is changed due to different carriers, and the fluctuation range of the output voltage is further influenced, the output voltage of the DC-DC converter in different fluctuation ranges is obtained.
5. The method for regulating the voltage of the photovoltaic power generation unit by fusing fault information transmission according to claim 1, wherein the demodulating according to the output voltage information of the output end and the determining the fault information of the photovoltaic module comprise:
according to the different fluctuation ranges of the direct current bus voltage, maximum value and minimum value detection is carried out on the output voltage of the DC-DC converter respectively by utilizing a maximum value detection method to obtain peak value information of the output voltage of the DC-DC converter, and the peak value information is compared with the peak value of the output voltage of the converter under the condition of no fault respectively to identify the fault information of the photovoltaic module.
6. The utility model provides a fuse photovoltaic power generation unit voltage regulation system of trouble information transmission which characterized in that, the system includes:
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 the carrier wave switching information; in the transmission process, acquiring a voltage value output by an output end of the DC-DC converter, subtracting a difference value between the voltage value output by the output end of the DC-DC converter and a given value from a carrier signal, and generating a PWM control signal for controlling a controllable element in the DC-DC converter 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, demodulating according to the output voltage information of the output end and determining the fault information of the photovoltaic module.
7. The system of claim 6, 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 the energy generated by the photovoltaic power generation end;
the first judgment unit is used for judging whether the photovoltaic power generation assembly has a shielding fault or not according to the change rate of the illumination intensity of the environment where the photovoltaic power generation assembly is located;
the second judging unit is used for judging the damage condition of the photovoltaic power generation assembly according to the change rate of the energy generated by the photovoltaic power generation end;
the fault judging unit is used for judging that the photovoltaic module has no fault when any change rate is equal to the change rate under the abnormal condition or does not exceed the preset range; and when the difference value between the change rate and the change rate under the abnormal condition is detected to be out of the preset range, the photovoltaic power generation assembly breaks down, and corresponding information of the broken down is used as initial fault information.
8. The system of claim 6, wherein the PWM signal generation module comprises:
the switching unit is used for switching the carrier wave of the 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 fluctuation range of the output voltage is influenced by the change of the duty ratio of the PWM control signal generated by the comparator due to different carriers.
9. The system of claim 6, wherein the information demodulation module comprises:
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 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 condition of no fault so as to identify the fault information of the photovoltaic module.
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