CN109301873B - Photovoltaic grid-connected power generation system - Google Patents
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Abstract
The invention discloses a technical scheme for solving the technical problems, which comprises the following steps: a photovoltaic grid-connected power generation system comprises a photovoltaic array, a junction box, a current converter, a storage battery, an inverter, a controller and a transformer; the photovoltaic array converts solar energy into electric energy to be output, and the electric energy sequentially passes through the combiner box, the inverter and the transformer and then is connected to an alternating current power grid; the storage battery is connected with the converter and then is connected to the output end of the combiner box; the controller is connected with the converter and the inverter. The invention has the beneficial effects that: the photovoltaic grid-connected power generation system can be used for photovoltaic power generation, and the provided inverter can detect and position faults, so that the power generation system is more stable and the safety performance is improved.
Description
Technical Field
The invention relates to the field of new energy grid-connected power generation control, in particular to a photovoltaic grid-connected system.
Background
In recent years, solar energy has attracted attention as a clean and environment-friendly energy source, and has been widely used in various occasions for over 20 years. Solar photovoltaic power generation is an important form of solar energy utilization, is a power generation form of converting light energy into electric energy by adopting a photovoltaic module, and is one of power generation technologies with the greatest development prospect probably along with the continuous progress of the technology.
The photovoltaic grid-connected power generation system is characterized in that direct current generated by a solar component is converted into alternating current meeting the requirements of a commercial power grid through a grid-connected inverter and then is directly connected to a public power grid. The photovoltaic grid-connected power generation system is a centralized large grid-connected power station which is generally a national-level power station and is mainly characterized in that generated energy is directly transmitted to a power grid and is uniformly regulated and supplied to users by the power grid; there are also distributed small grid-connected power generation systems, especially photovoltaic building integrated power generation systems, which are the mainstream of grid-connected power generation.
Disclosure of Invention
This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.
The present invention has been made in view of the above-mentioned conventional problems.
Therefore, the invention aims to provide a photovoltaic grid-connected power generation system for photovoltaic grid-connected power generation.
In order to solve the technical problems, the invention provides the following technical scheme: a photovoltaic grid-connected power generation system comprises a photovoltaic array, a junction box, a current converter, a storage battery, an inverter, a controller and a transformer; the photovoltaic array converts solar energy into electric energy to be output, and the electric energy sequentially passes through the combiner box, the inverter and the transformer and then is connected to an alternating current power grid; the storage battery is connected with the converter and then is connected to the output end of the combiner box; the controller is connected with the converter and the inverter.
As a preferable scheme of the photovoltaic grid-connected power generation system of the present invention, wherein: the device also comprises a direct current load and an alternating current load; part of direct current output by the photovoltaic array is connected into the direct current load for use, and part of direct current is connected into the inverter to be changed into alternating current; and the alternating current output by the inverter is respectively connected into an alternating current load and an alternating current power grid through voltage conversion of the transformer.
As a preferable scheme of the photovoltaic grid-connected power generation system of the present invention, wherein: the converter is connected with the storage battery and then connected to the output end of the combiner box in parallel, and the converter is a DC/DC converter; the inverter is a DC/AC inverter.
As a preferable scheme of the photovoltaic grid-connected power generation system of the present invention, wherein: the controller comprises a microprocessor and a signal sampling circuit, wherein the microprocessor acts on the current converter and the inverter by receiving signals of the signal sampling module and sending corresponding control signals, and backflow, overload and short circuit are prevented by switching on and off the control circuit.
As a preferable scheme of the photovoltaic grid-connected power generation system of the present invention, wherein: the inverter comprises a shell and electronic elements arranged in the inverter, a handle and a terminal post are further arranged on the side face of the shell, and the terminal post is connected with the electronic elements in the inverter.
As a preferable scheme of the photovoltaic grid-connected power generation system of the present invention, wherein: the inverter also comprises a bearing plate and a pressing block; the left end and the right end of the bearing plate are supported by the shell and are overhead, the bearing plate is divided into an upper surface and a lower surface, and the upper surface of the bearing plate is limited by the pressing block and the shell.
As a preferable scheme of the photovoltaic grid-connected power generation system of the present invention, wherein: the electronic element arranged above the bearing plate further comprises a grid-connected contactor, a direct-current power supply module, a power module, a cover plate and a voltage transformation module; the grid-connected contactor and the combiner box are in contact access to a circuit, are accessed to the power module through the direct-current power supply module, and finally are converted by the voltage transformation module and then output as alternating current; the cover plate is arranged on the top of the power module.
As a preferable scheme of the photovoltaic grid-connected power generation system of the present invention, wherein: the electronic element arranged below the bearing plate further comprises a filtering energy storage capacitor, an alternating current filtering capacitor and a terminal strip; the filtering energy storage capacitor module and the alternating current filtering capacitor can store electric energy in the capacitors and are arranged below the bearing plate to support the bearing plate; the terminal strip is arranged on one side of the alternating current filter capacitor.
As a preferable scheme of the photovoltaic grid-connected power generation system of the present invention, wherein: the inverter further includes a panel disposed on the housing; the panel also comprises an indicator light, a display screen and a key.
As a preferable scheme of the photovoltaic grid-connected power generation system of the present invention, wherein: the power module also comprises a power tube module and a driving module; the power tube module is connected with the connecting composite terminal strip and the absorption capacitor; the driving module drives the power tube module.
The invention has the beneficial effects that: the photovoltaic grid-connected power generation system can be used for photovoltaic power generation, and the provided inverter can detect and position faults, so that the power generation system is more stable and the safety performance is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:
fig. 1 is an overall framework schematic diagram of a photovoltaic grid-connected power generation system according to a first embodiment of the invention;
fig. 2 is an overall schematic diagram of an inverter in a grid-connected photovoltaic power generation system according to a second embodiment of the present invention;
fig. 3 is a schematic structural diagram of an inverter with an upper shell removed in a photovoltaic grid-connected power generation system according to a second embodiment of the present invention;
fig. 4 is a schematic structural diagram of a photovoltaic grid-connected power generation system according to a second embodiment of the present invention, in which a cover plate of an inverter is removed;
fig. 5 is a schematic structural diagram of a back side of an inverter in a grid-connected photovoltaic power generation system according to a second embodiment of the present invention;
fig. 6 is a schematic structural diagram of a power module in a grid-connected photovoltaic power generation system according to a second embodiment of the present invention;
fig. 7 is a schematic diagram of an IGBT structure layer in a method for detecting an open-circuit fault of a power tube according to a third embodiment of the present invention;
fig. 8 is a schematic diagram of a three-phase bridge topology in a method for detecting an open-circuit fault of a power tube according to a third embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments accompanied with figures are described in detail below, and it is apparent that the described embodiments are a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making creative efforts based on the embodiments of the present invention, shall fall within the protection scope of the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
Furthermore, the present invention is described in detail with reference to the drawings, and in the detailed description of the embodiments of the present invention, the cross-sectional view illustrating the structure of the device is not enlarged partially according to the general scale for convenience of illustration, and the drawings are only exemplary and should not be construed as limiting the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
Meanwhile, in the description of the present invention, it should be noted that the terms "upper, lower, inner and outer" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation and operate, and thus, cannot be construed as limiting the present invention. Furthermore, the terms first, second, or third are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The terms "mounted, connected and connected" in the present invention are to be understood broadly, unless otherwise explicitly specified or limited, for example: can be fixedly connected, detachably connected or integrally connected; they may be mechanically, electrically, or directly connected, or indirectly connected through intervening media, or may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example 1
As shown in fig. 1, a photovoltaic grid-connected power generation system provided by the present invention is schematically illustrated, and the system includes a photovoltaic array 100, a combiner box 200, a converter 300, a storage battery 400, an inverter 500, a controller 600, and a transformer 800. Specifically, the photovoltaic array 100 converts solar energy into electric energy to be output, and the electric energy is sequentially connected to an alternating current power grid after passing through the combiner box 200, the inverter 500 and the transformer 800; the photovoltaic array 100, i.e. the solar panel, is a core part of the solar power generation system and is also the most valuable part of the solar power generation system, and functions to convert the radiation energy of the sun into electric energy, or send the electric energy to a storage battery for storage or to enable a load to work.
The storage battery 400 is connected with the converter 300 and then is merged into the output end of the combiner box 200; the controller 600 is connected with the converter 300 and the inverter 500. The battery 400 is generally a lead-acid battery, and in a micro-miniature system, a nickel-metal hydride battery or a camel battery can be used, and the function of the battery is to store electric energy generated by a solar panel when the battery is illuminated and release the electric energy when the battery is needed. The direct output of solar energy is typically 12VDC, 24VDC, 48 VDC. In order to supply electric power to 220VAC appliances, DC power generated by a solar power generation system needs to be converted into AC power, and thus a DC/AC inverter needs to be used. The existing commonly used photovoltaic grid-connected power generation system has two structural forms, and the difference lies in whether a storage battery is arranged as an energy storage link.
The grid-connected photovoltaic power generation system without the storage battery link is called a non-dispatchable grid-connected photovoltaic power generation system, in the system, a grid-connected inverter converts direct current electric energy generated by a solar panel into alternating current electric energy with the same frequency and phase as the voltage of a power grid, and when the main power grid is powered off, the system automatically stops supplying power to the power grid. When sunlight irradiates and the alternating current electric energy generated by the photovoltaic system exceeds the requirement of a load, the redundant part is sent to a power grid; when the electric energy required by the load exceeds the alternating current electric energy generated by the photovoltaic system at night, the electric energy is automatically supplemented to the load by the power grid.
The photovoltaic grid-connected power generation system with the storage battery link is called a scheduling photovoltaic grid-connected power generation system, because an inverter in the system is provided with a main switch and an important load switch, the system has the function of an uninterruptible power supply, the scheduling photovoltaic grid-connected power generation system has a plurality of extensions and improvements in the aspects of functions and performance compared with a non-scheduling type, and a core converter generally consists of a grid-connected inverter and a storage battery charger. The solar energy storage system has the functions of not only inverting the direct current electric energy generated by the solar cell array and then transmitting the inverted direct current electric energy to a power grid, but also charging a storage battery after DC/DC conversion; the dispatchable system can not only feed sine wave electric energy with the same frequency and phase to the power grid, but also serve as a power regulator to stabilize the voltage of the power grid and counteract harmful higher harmonic components, so that the electric energy quality is improved. In addition, the high-power dispatching type photovoltaic grid-connected power generation device can freely determine the magnitude of grid-connected current according to the operation requirement, and the peak shaving of a power grid is facilitated. When the load of the power grid is increased, the grid-connected current of the photovoltaic grid-connected power generation device can be scheduled and increased, and the operation quality of the power grid is facilitated.
Further, the system further comprises a direct current load 700 and an alternating current load 900; part of the direct current output by the photovoltaic array 100 is connected into the direct current load 700 for use, and part of the direct current is connected into the inverter 500 to be changed into alternating current; the alternating current output by the inverter 500 is converted by the transformer 800 and respectively connected to the alternating current load 900 and the alternating current grid, and the converter 300 is connected with the storage battery 400 and then connected to the output end of the combiner box 200 in parallel, which is a DC/DC converter; inverter 500 is a DC/AC inverter. The dc load 700 and the ac load 900 referred to in this embodiment are, for example, a dc consumer and an ac consumer.
Further, the controller 600 in the system includes a microprocessor and a signal sampling circuit, and the microprocessor acts on the converter 300 and the inverter 500 by receiving the signal from the signal sampling module and sending a corresponding control signal, including the disconnection of the control circuit, to prevent backflow, overload, and short circuit. The solar controller is used for controlling the working state of the whole system and has the functions of overcharge protection and over-discharge protection on the storage battery. In places with large temperature difference, the qualified controller also has the function of temperature compensation, and other additional functions such as a light-operated switch and a time-controlled switch are optional items of the controller. For example, the microprocessor is implemented by using an existing FPGA or PI control loop, wherein the PI regulator is a linear controller, and forms a control deviation according to a given value and an actual output value, and linearly combines the proportion and the integral of the deviation to form a control quantity to control a controlled object. The FPGA is a product which is further developed on the basis of programmable devices such as PAL, GAL, CPLD and the like, and is used as a semi-custom circuit in the field of special integrated circuits, thereby not only solving the defects of the custom circuit, but also overcoming the defect of limited gate circuits of the original programmable devices. The logic cell array LCA is adopted by referring to the existing FPGA, and the logic cell array LCA internally comprises a configurable logic module, an input-output module IOB and an internal connecting line. A field programmable gate array is a programmable device that has a different structure than traditional logic circuits and gate arrays, such as PAL, GAL and CPLD devices. The FPGA utilizes small lookup tables to realize combinational logic, each lookup table is connected to the input end of a D flip-flop, and the flip-flops drive other logic circuits or drive I/O (input/output) circuits, so that basic logic unit modules capable of realizing both combinational logic functions and sequential logic functions are formed, and the modules are mutually connected or connected to the I/O modules by utilizing metal connecting wires. The logic of the FPGA is implemented by loading programming data into the internal static memory cells, the values stored in the memory cells determine the logic function of the logic cells and the way of the connections between the modules or between the modules and the I/O and finally the functions that can be implemented by the FPGA, which allows an unlimited number of programming. Further, the transformer 800 is a device for changing an alternating voltage using the principle of electromagnetic induction, and main components are a primary coil, a secondary coil, and an iron core or a magnetic core. The transformer consists of an iron core (or a magnetic core) and a coil, wherein the coil is provided with two or more than two windings, the winding connected with a power supply is called a primary coil, and the other windings are called secondary coils, so that alternating voltage, current and impedance can be converted. It should be further noted that, in the present embodiment, the electronic components related to the system may refer to the prior art, and the electrical connection in the electrical system is adopted, and certainly, the wiring and the connection that the circuit completes the connection are included, which are all the implicitly disclosed parts in the present embodiment, and those skilled in the art can implement the connection in combination with the common knowledge.
Example 2
Referring to the illustrations of fig. 2 to 6, in the present embodiment, an inverter is provided for a photovoltaic grid-connected power generation system of the above embodiments, where the inverter 500 includes a housing 501, a loading plate 502, a pressing block 503, a grid-connected contactor 504, a dc power module 505, a power module 506, a cover plate 507, a transformation module 508, a filtering energy storage capacitor 509, an ac filtering capacitor 510, a terminal row 511, and a panel 512, which are disposed on the inverter 500. Specifically, the housing 501 arranged in six sides can form a containing space of the inverter 500, the electronic components are arranged inside the inverter 500, the handle 501a and the terminal column 501b are further arranged on the side surface of the housing 501, the terminal column 501b is connected with the electronic components inside, the handle 501a is used for users to use the inverter 500, and the terminal column 501b is used for outputting or accessing electric energy, and the arrangement can be reasonable here, and the output and input ports are not limited. The both ends are supported by shell 501 and are maked somebody a mere figurehead about loading board 502, and divide into upper and lower two sides, and it is spacing through compact heap 503 and shell 501 above the loading board 502, and loading board 502 is the circuit board, sets up the microcircuit on it, has the general function that circuit board has. It is understood that the carrier plate 502 is divided into a front surface and a back surface, and the two surfaces are connected by a circuit soldered on the circuit board, so that the components disposed on the front surface and the back surface of the carrier plate 502 can be electrically connected to form a desired circuit. Further, the electronic component disposed above the bearing plate 502 further includes a grid-connected contactor 504, a dc power module 505, a power module 506, a cover plate 507 and a voltage transformation module 508, the grid-connected contactor 504 and the junction box 200 contact the circuit, and the circuit is connected to the power module 506 through the dc power module 505, and finally the voltage is transformed by the voltage transformation module 508 and then output as an alternating current; a cover plate 507 is disposed on top of the power module 506. The upper part of the cover plate 507 is abutted against the shell, and the lower part is abutted against the power module 506, so that the power module 506 is limited up and down. Still further, the electronic component disposed below the carrier plate 502 in this embodiment further includes a filtering energy storage capacitor 509, an ac filtering capacitor 510, and a terminal row 511; the filtering energy storage capacitor module 509 and the ac filtering capacitor 510 can store electric energy in the capacitors, and are disposed below the carrier plate 502 to support the same; terminal block 511 is disposed on one side of ac filter capacitor 510. The filter capacitor is an energy storage device which is arranged at two ends of the rectifying circuit and used for reducing alternating current ripple coefficients and improving high-efficiency smooth direct current output, and in a direct current power transmission system, in order to filter harmonic waves generated by a direct current control system so as to avoid adverse effects on the alternating current power transmission system and compensate reactive power consumed by the direct current control system, a certain number of alternating current filters are required to be added in the running process of the direct current system. The alternating current filter is composed of a capacitor, a reactor and a resistor which are connected in series-parallel. The terminal block 511 is used for connection between the components. The inverter 500 further includes a panel 512 disposed on the housing 501; the panel 512 also includes indicator lights, a display screen, and keys. In this embodiment, the power module 506 further includes a power tube module 506a and a driving module 506 b; the power tube module 506a is connected with the connection composite terminal row 506c and the absorption capacitor 506 d; the driving module 506b drives the power tube module 506 a. For example, the driver can adopt 1SC2060P2Ax-17, which is a single-channel high-power high-frequency SCALE-2 driving core introduced by PI company, and adopts newly developed planar transformer technology to realize a real leap in power density, noise resistance and reliability. The high-performance SCALE-2 driving core is mainly designed for driving a high-power single-channel IGBT module and an MOSFET module, and has the functions of isolated DC/DC power supply, short-circuit protection, advanced active clamping and power supply voltage monitoring. The absorption capacitor 506d functions in the circuit like a low pass filter and can absorb spike voltages. The method is generally used for the insulated gate bipolar transistor, eliminates peak voltage caused by stray inductance of a busbar and avoids damage of the insulated gate bipolar transistor. It should be noted that the power module 506 is a circuit board, but it is not difficult for those skilled in the art to find that the power module is not limited to the above-mentioned electronic components, and should include components that satisfy the requirement of a complete circuit board, such as circuit breakers, soldered lines, pin ports, etc., and reference may be made to the layout of the existing circuit board, which belongs to the hidden disclosure and will not be described in detail.
Example 3
Based on the converter 300 and the inverter 500 applied to the photovoltaic grid-connected power generation system provided by the above embodiments, the embodiment provides a power tube open-circuit fault detection method to detect and locate a fault. In particular, the voltage source converter is a converter consisting of devices with turn-off capability, such as insulated gate bipolar transistors, IGBTs. The converters are equipment for performing alternating current and direct current conversion and are composed of a single converter bridge or a plurality of converter bridges, and can be divided into two types: a rectifier and an inverter, wherein the rectifier converts alternating current to direct current and the inverter converts direct current to alternating current. The inverter is also a frequency converter which can change the alternating current from one frequency to another frequency, and the conversion process is completed by the frequency change. And is therefore also referred to as a frequency converter. It will be understood that the converter 300 in the above-described grid-connected pv system is identical to the inverter 500 in actual principle, but differs therefrom only in that it functions differently in the circuit.
The global photovoltaic power generation industry is rapidly increased, the industrial scale is continuously enlarged, and the national photovoltaic power generation industry is rapidly developed. As the core of the photovoltaic grid-connected control, the converter plays a key control role, once an open circuit fails, a large amount of harmonics are generated, the three-phase balance is affected, the output power is reduced, and the like, while the IGBT module in the converter is a main device that fails, and the IGBT module referred to here can be understood as the power module 506 in the inverter 500 in the above embodiment, which is a composite fully-controlled voltage-driven power semiconductor device composed of a bipolar triode and an insulated gate field effect transistor, and has the advantages of both high input impedance and low conduction voltage drop. The open-circuit fault of the IGBT is an open circuit caused by overcurrent burning on one hand, and a drive signal open circuit caused by poor wiring, drive disconnection and the like on the other hand. The influence of the open-circuit fault of the converter has latency and can damage equipment, an IGBT module in the converter is a great deal of research on the fault, one of the main devices is provided, and the method for detecting the fault of the converter bridge power tube surrounds the method for detecting the fault of the converter bridge power tube and the method for detecting the open-circuit fault by students and experts at home and abroad. Among them, practical, simple and effective methods are the three-phase average current method, the average current park vector method, and the fourier-based normalization method. The direct three-phase average current method is to directly calculate the average value of the three-phase current in each period and judge whether a fault occurs by comparing the average value of the three-phase current with a set threshold value. These methods are most straightforward, but have poor interference rejection and poorly defined failures at low loads. Compared with a direct average direct current method, the average current park vector method saves unnecessary links, has higher diagnosis speed, and still has limited anti-interference capability. The normalization method based on Fourier transform firstly performs Fourier transform on each phase current, finally performs normalization processing on the fundamental component and the direct current component of the phase current, and diagnoses and positions faults by comparing normalized values. The method can effectively eliminate noise interference, but can only judge the fault of a single tube. In view of the existing problems described above.
The present embodiment provides a method for detecting an open-circuit fault of a power tube, which refers to the schematic diagram of fig. 7, and is a schematic diagram of an IGBT structure layer, where the IGBT structure corresponds to a power module 506 in an inverter 500. It should be noted that the schematic diagram of the IGBT structure in the drawing is only a schematic diagram, and cannot represent an actual structure, and the power module 506 in the inverter 500 is a schematic diagram of a product after actual molding, as illustrated in fig. 7, the schematic structure includes a copper bus, a bus solder layer, an aluminum wire, a chip solder, A1N, a Cu layer, a substrate, and a copper base plate, and the method for detecting an open circuit fault of a power tube is implemented by relying on the chip here, where the chip corresponds to the driving module 506b of the above embodiment, and the actual product diagram is formed by soldering the chip solder, and performs open circuit fault detection of the power tube according to a detection signal, and the power tube module 506a includes an IGBT valve. Although not shown in the actual drawings, the aluminum wires, the copper bus bars, the bus bar solder layers, and the like can be arranged on the circuit board in a specific manner as will be readily apparent to those skilled in the art.
Referring to the schematic of fig. 8, the method further comprises the following steps: the normalization method only focuses on the direct current component and the fundamental wave component of the current, and can effectively reduce the influence caused by noise. The normalization principle calculation formula based on Fourier transform is as follows:
wherein formula (1-1) calculates the real component, i, of each waveform of the full-cycle Fourier transformj(n) is a sampling value of an nth point of a cycle of each phase current, and k represents the number of times of each subharmonic, and the value is 0, 1, 3, 5 and 7; the formula (1-2) calculates the imaginary component of each waveform of the full-cycle Fourier transform, and the value of the imaginary component is similar to the value of the formula (1-1); the ratio of the DC component to the fundamental component of each phase current, a, is calculated by the equation (1-3)j·0The direct component of the respective phase current, aj·1Representing the real part of the fundamental component of the respective phase current, bj·1The imaginary part of the fundamental component of each phase current is shown.
The key point for realizing the method is the judgment of the normalization method hjIs a normalized value representing the ratio of the dc component to the fundamental component. Under an ideal operation condition, the waveform of the current is close to a sine wave, and the direct-current component is 0 after Fourier transform; in the case of noise interference, the waveform of the current has a sudden change, so that the direct current component can be divided by Fourier transformThe quantity appears, but at the moment, although the waveform interfering one period is still complete, the fundamental wave component is very large and is larger than the direct current component; in the event of a failure of an IGBT valve, the current may lack a half-cycle waveform over a full cycle, which causes the dc component to be greater than the fundamental component, thereby distinguishing it from the value in the case of a disturbance. Therefore, a normalization criterion can be determined, and a switch of the a-phase bridge arm is taken as an example. In actual operation, the dc component of the current that may be disturbed under normal conditions is not zero, but the normalized value is only smaller than 1, so that a value P and a function f can be assumeda·1The normalized absolute value | h of the a-phase current is denoted by PaAnd | for judging the condition whether the fault occurs. If P is greater than 1, the function fa·11, otherwise function fa·10. In addition, fault localization is required, so another value Q and function f can be assumeda·2The normalized value of the fourier transform of the a-phase current is denoted by Q. Because the missing parts of the current waveforms are complementary when the upper and lower switches are in fault, the normalized value of the current Fourier also has a positive-negative relation and is related to the operation state of the converter. If Q is greater than 0, function fa·21, otherwise function fa·21. The expression is shown as the following formula.
See table 1 below for fault location table when the converter rectifies the state, the switch fault is judged and the location condition is as shown in the table:
| fault switch | fa·1 | fb·1 | fc·1 | fa·2 | fb·2 | fc·2 |
| T1 | 1 | 1 | ||||
| T2 | 1 | 1 | ||||
| T3 | 1 | 1 | ||||
| T4 | 1 | 0 | ||||
| T5 | 1 | 0 | ||||
| T6 | 1 | 0 |
Under normal conditions, the probability of a single IGBT valve failing is high, but multiple pipe failures are less common unless large variations in system parameters or large accidents occur. Although the occurrence probability is small, the occurrence probability still exists, and therefore, the multi-target open-circuit fault detection research of the photovoltaic grid-connected power generation system still has value. For a direct average current method and an average current park vector method, multi-target fault judgment can be realized through improvement, but the judgment links are many, the process is complex, and the interference resistance is a problem. The normalization method can be operated independently in a split-phase mode, and detection judgment results can be simplified.
There are many situations of multi-target faults of a converter or an inverter of a photovoltaic grid-connected power generation system, and a proper detection judgment standard needs to be formulated according to various specific situations. The criterion of the normalization method for single switch faults is analyzed, and the corresponding phase current of the fault arm is aimed at, so that the multiple-tube faults can be diagnosed by simultaneously detecting each phase current by utilizing the independent criterion of the normalization method.
The following analysis is made for the faults of the various switches, first f(a·1)、f(b·1)、f(c·1)、f(a·2)、f(b·2)、f(c·2)Set 6 as a code. Firstly, the code of the first three bits is 000, then one step of additional judgment is needed, because if the upper switch and the lower switch of the same arm have open circuit faults, f in the criterion is(a·1)、f(b·1)、f(c·1)Still 0, at which time an ac current criterion is added. If any alternating current is 0, the fault of the upper and lower switches of the phase is directly determined without codes, and if the fault is a theorem for directly judging the fault of the upper and lower switches of the multi-phase by the aid of the multi-phase current. After the additional current judgment, the judgment basis of the fault of the multi-target switching tube is shown in the following table 2.
Thus, the fault judgment and the switch tube positioning of two or three switches can be carried out only by judging the codes according to the fault normalization method. If a particularly serious fault occurs, such as an open-circuit fault of 4 or even 5 switching tubes, which phase or two-phase full-arm fault is judged by current, and the fault condition of the switching tubes of other phases is located by a normalization code. If the most serious fault occurs and the three-phase current is totally lost, all IGBT valves have open-circuit faults.
Compared with the prior art, the method has the following advantages: the anti-interference capability is strong: the method can obviously distinguish the detection values under the interference condition and the fault condition, has better anti-interference capability than a direct average current method and an average current park vector method, and is more practical in application; the fault discrimination is more effective: the new criterion is used for judging the faults and positioning the switch tube without limitation, and the new criterion can be used for solving the open-circuit faults of two or more IGBT valves; the method is easy to realize: the control method only needs to measure the current and the voltage, does not need excessive hardware and detection equipment, greatly saves the hardware cost, and is simple and easy to realize.
It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (9)
1. A grid-connected photovoltaic power generation system is characterized in that: the photovoltaic power generation system comprises a photovoltaic array (100), a combiner box (200), a converter (300), a storage battery (400), an inverter (500), a controller (600) and a transformer (800);
the photovoltaic array (100) converts solar energy into electric energy to be output, and the electric energy sequentially passes through the combiner box (200), the inverter (500) and the transformer (800) and then is connected to an alternating current power grid; the storage battery (400) is connected with the converter (300) and then is merged into the output end of the combiner box (200); the controller (600) is connected with the converter (300) and the inverter (500);
the direct current load (700), the direct current output by the photovoltaic array (100) is partially connected into the direct current load (700) for use, and is partially connected into the inverter (500) to be changed into alternating current;
the inverter (500) comprises a shell (501) and electronic elements arranged inside the inverter (500), a handle (501a) and a terminal column (501b) are further arranged on the side face of the shell (501), the terminal column (501b) is connected with the electronic elements inside, and a bearing plate (502) and a pressing block (503) are further arranged inside the inverter (500); the electronic element arranged above the bearing plate (502) further comprises a grid-connected contactor (504), a direct-current power supply module (505), a power module (506), a cover plate (507) and a voltage transformation module (508);
the converter (300) comprises 6 converter bridges, and the switching state of the 6 converter bridges is f(a〃1)、f(b〃1)、f(c〃1)、f(a〃2)、f(b〃2)、f(c〃2)Setting the code to 6 bits, and setting the code of the first three bits to 000, adding one step of additional judgment, because if the upper and lower switches of the same arm have open circuit faults, and f in the judgment(a〃1)、f(b〃1)、f(c〃1)And if the current is the multiphase current, the fault of the upper and lower switches of the phase is directly judged without codes.
2. The grid-connected photovoltaic power generation system according to claim 1, characterized in that: the alternating current power supply system further comprises an alternating current load (900), and alternating current output by the inverter (500) is connected into the alternating current load (900) and an alternating current power grid respectively through voltage conversion of the transformer (800).
3. The grid-connected photovoltaic power generation system according to claim 1 or 2, characterized in that: the converter (300) is connected with the storage battery (400) and then connected to the output end of the combiner box (200) in parallel, and the converter is a DC/DC converter; the inverter (500) is a DC/AC inverter.
4. The grid-connected photovoltaic power generation system according to claim 3, characterized in that: the controller (600) comprises a microprocessor and a signal sampling circuit, the microprocessor acts on the current converter (300) and the inverter (500) by receiving signals of the signal sampling module and sending corresponding control signals, and backflow, overload and short circuit are prevented by the microprocessor through the on-off of the control circuit.
5. The grid-connected photovoltaic power generation system according to claim 4, characterized in that:
the left end and the right end of the bearing plate (502) are supported by the shell (501) and are overhead, the bearing plate is divided into an upper surface and a lower surface, and the upper surface of the bearing plate (502) is limited by the pressing block (503) and the shell (501).
6. The grid-connected photovoltaic power generation system according to claim 5, characterized in that:
the grid-connected contactor (504) is in contact with the junction box (200) to be connected into a circuit, is connected into the power module (506) through the direct-current power supply module (505), and is finally subjected to voltage conversion by the voltage transformation module (508) and then is output as alternating current; the cover plate (507) is disposed on top of the power module (506).
7. The grid-connected photovoltaic power generation system according to claim 6, characterized in that: the electronic element arranged below the bearing plate (502) further comprises a filtering energy storage capacitor (509), an alternating current filtering capacitor (510) and a terminal block (511);
the filtering energy storage capacitor (509) and the alternating current filtering capacitor (510) can store electric energy in the capacitors and are arranged below the bearing plate (502) to support the bearing plate; the terminal block (511) is arranged on one side of the alternating current filter capacitor (510).
8. The grid-connected photovoltaic power generation system according to any one of claims 5 to 7, characterized in that: the inverter (500) further comprises a panel (512) disposed on the housing (501); the panel (512) further comprises an indicator light, a display screen and a key.
9. The grid-connected photovoltaic power generation system according to claim 6, characterized in that: the power module (506) further comprises a power tube module (506a) and a driving module (506 b); the power tube module (506a) is connected with a connection composite terminal row (506c) and an absorption capacitor (506 d); the driving module (506b) drives the power tube module (506 a).
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101345500A (en) * | 2008-05-16 | 2009-01-14 | 广东志成冠军集团有限公司 | Photovoltaic power generation system with grid-connected generation, independent power generation and UPS function |
| CN102237691A (en) * | 2011-07-06 | 2011-11-09 | 东北大学 | Wind energy and solar energy grid-connected generation system and control method thereof |
| CN102412598A (en) * | 2011-12-12 | 2012-04-11 | 辽宁省电力有限公司锦州供电公司 | Minitype intelligent bidirectional self-adaptation grid-connected photovoltaic power generation system and control method thereof |
| CN105450043A (en) * | 2014-09-28 | 2016-03-30 | 中车大连电力牵引研发中心有限公司 | Traction inversion module and traction inverter |
| CN206077248U (en) * | 2016-08-15 | 2017-04-05 | 浙江京禾电子科技有限公司 | Photovoltaic DC-to-AC converter |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102916442A (en) * | 2012-10-17 | 2013-02-06 | 北京科诺伟业科技有限公司 | Building photovoltaic grid-connected system |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101345500A (en) * | 2008-05-16 | 2009-01-14 | 广东志成冠军集团有限公司 | Photovoltaic power generation system with grid-connected generation, independent power generation and UPS function |
| CN102237691A (en) * | 2011-07-06 | 2011-11-09 | 东北大学 | Wind energy and solar energy grid-connected generation system and control method thereof |
| CN102412598A (en) * | 2011-12-12 | 2012-04-11 | 辽宁省电力有限公司锦州供电公司 | Minitype intelligent bidirectional self-adaptation grid-connected photovoltaic power generation system and control method thereof |
| CN105450043A (en) * | 2014-09-28 | 2016-03-30 | 中车大连电力牵引研发中心有限公司 | Traction inversion module and traction inverter |
| CN206077248U (en) * | 2016-08-15 | 2017-04-05 | 浙江京禾电子科技有限公司 | Photovoltaic DC-to-AC converter |
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