CN113746314B - Photovoltaic inverter and starting control method - Google Patents
Photovoltaic inverter and starting control method Download PDFInfo
- Publication number
- CN113746314B CN113746314B CN202111291275.1A CN202111291275A CN113746314B CN 113746314 B CN113746314 B CN 113746314B CN 202111291275 A CN202111291275 A CN 202111291275A CN 113746314 B CN113746314 B CN 113746314B
- Authority
- CN
- China
- Prior art keywords
- module
- photovoltaic
- input
- inverter
- circuit current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims description 28
- 238000005286 illumination Methods 0.000 claims abstract description 66
- 239000003990 capacitor Substances 0.000 claims abstract description 31
- 238000001514 detection method Methods 0.000 claims description 30
- 238000005070 sampling Methods 0.000 claims description 7
- 238000010586 diagram Methods 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/36—Means for starting or stopping converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
- H02S40/30—Electrical components
- H02S40/32—Electrical components comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a photovoltaic inverter, comprising: the input end receives direct current electric energy provided by the photovoltaic module; the inversion module inverts the direct current electric energy provided by the photovoltaic module into alternating current electric energy; the relay controls the connection of the inversion module and the power grid; the control module controls the operation states of the inversion module and the relay; the auxiliary power supply module supplies power to the control module according to direct current electric energy provided by the photovoltaic module, the control module calculates to obtain approximate short-circuit current of the photovoltaic module according to input voltage of an input end, a capacitance value of an input capacitor and starting voltage of the auxiliary power supply module, judges the illumination state of the photovoltaic module according to the approximate short-circuit current, prohibits the inversion module and the relay from running when the illumination state is a weak light state, and permits the inversion module and the relay to run when the illumination state is a non-weak light state. The invention avoids the frequent startup and shutdown of the photovoltaic inverter in a low-light state.
Description
Technical Field
The invention relates to the technical field of photovoltaic inverters, in particular to a photovoltaic inverter and a starting control method.
Background
A photovoltaic inverter generally includes an inverter circuit, a controller, a relay, and an auxiliary power supply for supplying power to the controller. In order to reduce the nighttime power consumption of the photovoltaic inverter, an auxiliary power supply of the photovoltaic inverter generally takes electricity from a direct current input end. The relay is used for disconnecting the electrical connection between the photovoltaic power supply and the power grid when the power grid is abnormal, and the operation safety of power grid maintenance personnel is guaranteed. Under the low light conditions of morning and evening, cloudy and the like, due to the special output characteristics of the photovoltaic module, although the output power is very low, the open-circuit voltage is still high and usually exceeds the lowest input starting voltage of the photovoltaic inverter, after the photovoltaic inverter is started to operate, the output voltage of the photovoltaic module is quickly pulled down until the photovoltaic inverter performs input under-voltage protection, if the output power of the photovoltaic module is smaller than the operating power of an auxiliary power supply of the photovoltaic inverter, the output voltage of the photovoltaic module is further pulled down until the auxiliary power supply stops operating due to input under-voltage, the controller of the photovoltaic inverter is powered down, and the output relay of the controller is also disconnected due to the power down of the controller. The startup and shutdown process is usually repeated for many times under the condition of weak light, the switching times of a relay in the photovoltaic inverter are correspondingly increased for many times, the relay is a mechanical switch, the service life of the switching times is limited, the service life of the inverter is greatly shortened due to frequent startup and shutdown in a weak light state, and the service life of the inverter is shortened.
In order to solve the problem that the photovoltaic inverter is frequently turned on and turned off in a low-light state, a solution in the prior art is to add a dummy load circuit at the input end of the photovoltaic inverter and judge whether the output power of the photovoltaic module meets the starting condition of the photovoltaic inverter according to the power of the dummy load, but this solution adds an additional circuit and increases the cost of the photovoltaic inverter.
The other solution is to detect the open-circuit voltage of the photovoltaic module or the string, and judge whether the starting condition is met according to the magnitude of the open-circuit voltage. Due to the output characteristics of the photovoltaic module, the open-circuit voltages of the photovoltaic module under different illumination conditions are similar and are easily influenced by temperature, the current real illumination intensity condition is not completely reflected, and the probability of misjudgment is high.
Disclosure of Invention
Aiming at the existing problems, the invention provides a photovoltaic inverter and a photovoltaic inverter starting control method, which avoid the frequent startup and shutdown of the photovoltaic inverter in a low-light state.
To achieve the above object, the present invention provides a photovoltaic inverter including:
the input end is used for connecting the photovoltaic module and receiving direct current electric energy provided by the photovoltaic module;
the inversion module is connected with the input end, comprises an input capacitor and an inversion unit and is used for inverting the direct current electric energy provided by the photovoltaic module into alternating current electric energy;
the relay is connected between the output ends of the inversion module and the photovoltaic inverter and is used for controlling the connection between the inversion module and a power grid;
the control module is respectively connected with the inversion module and the relay and is used for controlling the operation states of the inversion module and the relay;
the auxiliary power supply module is connected with the input end and supplies power to the control module according to the direct current electric energy provided by the photovoltaic module;
the control module calculates to obtain an approximate short-circuit current of the photovoltaic module according to the input voltage of the input end, the capacitance value of the input capacitor and the starting voltage of the auxiliary power supply module, judges the illumination state of the photovoltaic module according to the approximate short-circuit current of the photovoltaic module, prohibits the inverter module and the relay from operating when the illumination state is a weak light state, and permits the inverter module and the relay to operate when the illumination state is a non-weak light state.
Further, when the input voltage reaches the starting voltage of the auxiliary power supply module, the auxiliary power supply module supplies power to the control module; the control module is started and acquires a first input voltage representing the current input voltage of the input end after a first preset time, calculates an approximate short-circuit current of the photovoltaic module according to the first input voltage, the capacitance value of the input capacitor, the starting voltage and the first preset time, and judges the illumination state of the photovoltaic module according to the approximate short-circuit current of the photovoltaic module.
Further, the calculation formula of the approximate short-circuit current Isc of the photovoltaic module is as follows:
the method includes the steps of obtaining an input voltage, obtaining a start voltage, obtaining a Δ T1, and obtaining an input current of an auxiliary power supply module, wherein Isc is an approximate short-circuit current of a photovoltaic module, C is a capacitance value of an input capacitor of a photovoltaic inverter, V1 is a first input voltage, Vstart is the start voltage, Δ T1 is a first preset time, and Iaux is the input current of the auxiliary power supply module.
Further, the first preset time is in an inverse relation with a capacitance value of the input capacitor, and the larger the capacitance value of the input capacitor is, the smaller the first preset time is.
Further, the control module includes:
the sampling unit is used for collecting input and output electrical parameters of the photovoltaic inverter, and the input and output electrical parameters comprise input voltage;
the weak light detection unit is used for detecting the illumination state of the photovoltaic module, acquiring a first input voltage acquired by the sampling unit after a first preset time passes after the control module is started, calculating to obtain an approximate short-circuit current of the photovoltaic module according to the first input voltage, the capacitance value of the input capacitor, the starting voltage and the first preset time, and comparing the approximate short-circuit current with a preset current threshold value to generate a detection signal representing that the illumination state of the photovoltaic module is a weak light state or a non-weak light state;
and the control unit controls the operation states of the inversion module and the relay according to the detection signal and the input and output electrical parameters, prohibits the operation of the inversion module and the relay when the detection signal is characterized to be in a weak light state, and controls the inversion module and the relay to start to operate when the detection signal is characterized to be in a non-weak light state and the input and output electrical parameters are within a normal range.
Further, when the approximate short-circuit current is larger than the current threshold, the light state is judged to be not the weak light state, otherwise, the light state is judged to be the weak light state.
Further, when the illumination state is a low-light state, after a second preset time, the control module allows the inverter module and the relay to operate.
Further, the second preset time is set to 5 to 20 minutes.
In order to achieve the above object, the present invention provides a method for controlling the start-up of a photovoltaic inverter, the method comprising:
calculating to obtain the approximate short-circuit current of the photovoltaic module according to the input voltage of the input end of the photovoltaic inverter, the capacitance value of the input capacitor and the starting voltage of the auxiliary power supply module;
and judging the illumination state of the photovoltaic module according to the approximate short-circuit current of the photovoltaic module, prohibiting the operation of the inversion module and the relay when the illumination state is a weak light state, and allowing the operation of the inversion module and the relay when the illumination state is a non-weak light state.
Further, the method comprises:
when the input voltage reaches the starting voltage of the auxiliary power supply module and the auxiliary power supply module is stably started, the auxiliary power supply module supplies power to the control module;
the control module is started and acquires a first input voltage representing the current input voltage of the input end after a first preset time, calculates an approximate short-circuit current of the photovoltaic module according to the first input voltage, the capacitance value of the input capacitor, the starting voltage and the first preset time, and judges the illumination state of the photovoltaic module according to the approximate short-circuit current of the photovoltaic module.
Compared with the prior art, the photovoltaic inverter and the starting control method thereof have the beneficial effects that: the method comprises the steps of collecting input voltage of the photovoltaic inverter, calculating approximate short-circuit current of the photovoltaic module according to the input voltage, judging the illumination state of the photovoltaic module according to the approximate short-circuit current, controlling the photovoltaic inverter to start according to the illumination state, further comparing the approximate short-circuit current with a current threshold value, if the current environment illumination state is judged to be in a weak light state, prohibiting an inversion module and a relay of the photovoltaic inverter from starting, allowing the photovoltaic inverter to start and operate after a certain time, and if the current environment illumination intensity is judged to be in a non-weak light state, allowing the photovoltaic inverter to start and operate. The starting method avoids the time period of frequent startup and shutdown in the low-light state, effectively reduces the frequency of frequent startup of the photovoltaic inverter in the low-light state, prolongs the service life of the photovoltaic inverter, simultaneously does not need to increase hardware circuits to detect the illumination intensity, and reduces the cost. Meanwhile, the control method is simple and has a wide application range. Because the short-circuit current is sensitive to the illumination intensity, the method is not easy to misjudge and has high accuracy. Compared with the traditional short-circuit current detection scheme, the method and the device have the advantages that the deviation between the approximate short-circuit current obtained by calculation in the low-light state and the actual short-circuit current can be reduced to about 20mA, and the detection precision is greatly improved.
Drawings
Fig. 1 is a graph of the output characteristics I-V of a photovoltaic module.
Fig. 2 is a block diagram of a photovoltaic inverter according to an embodiment of the present invention.
Fig. 3 is a schematic diagram illustrating a starting control principle of the photovoltaic inverter according to the embodiment of the present invention.
Fig. 4 is a graph of input voltage versus time during startup of a photovoltaic inverter in a low light condition in accordance with an embodiment of the present invention.
Fig. 5 is a graph of input voltage versus time during startup of a photovoltaic inverter in a non-dim light condition in accordance with an embodiment of the present invention.
Fig. 6 is a flowchart illustrating a method for controlling the start-up of the photovoltaic inverter according to an embodiment of the present invention.
Fig. 7 is a flowchart illustrating a photovoltaic inverter startup control method according to another embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to the specific embodiments shown in the drawings, which are not intended to limit the present invention, and structural, methodological, or functional changes made by those skilled in the art according to the specific embodiments are included in the scope of the present invention.
FIG. 1 is a graph of output characteristics I-V of a photovoltaic module, as shown in FIG. 1, in which a curve 1, a curve 2, a curve 3, and a curve 4 respectively represent the external illumination intensity at 1000W/m2、600 W/m2、100 W/m2、10 W/m2I-V curve of time. As can be seen from FIG. 1, the short-circuit current of the photovoltaic module under different illumination intensities is largeThe difference is small, the short-circuit current increases along with the increase of the illumination intensity, and the strong positive correlation is formed. Under the same illumination intensity, the output current of the photovoltaic module is basically stable and unchanged in the initial stage, and shows a rapid descending trend after the maximum power point is crossed. The output voltage of the photovoltaic module linearly increases in the output current stabilization stage, the output voltage of the photovoltaic module tends to be stable in the output current rapid reduction stage, and the open-circuit voltage of the photovoltaic module under different illumination intensities has small difference and is in a weak correlation relationship.
According to the analysis, the illumination state of the photovoltaic module can be judged through the short-circuit current of the photovoltaic module, so that the control method can judge the current illumination state according to the approximate short-circuit current of the photovoltaic module, and then the photovoltaic inverter is turned off in a low-light state to reduce the switching times of the relay of the photovoltaic inverter, the service life of the inverter can be prolonged, and the cost of the inverter can be reduced. The technical solution of the present invention will be described in detail by specific examples below.
Fig. 2 is a block diagram of a photovoltaic inverter provided according to an embodiment of the present invention, the photovoltaic inverter including:
the input end 20 is used for connecting the photovoltaic module and receiving direct current electric energy provided by the photovoltaic module;
the inverter module 21 is connected to the input end 20, and includes an input capacitor Cin and an inverter unit 211, configured to invert the dc power provided by the photovoltaic module into ac power;
the relay 22 is connected between the inverter module 21 and the output end of the photovoltaic inverter and is used for controlling the connection between the inverter module 21 and a power grid;
the control module 23 is respectively connected with the inverter module 21 and the relay 22 and is used for controlling the operation states of the inverter module 21 and the relay 22;
an auxiliary power supply module 24 connected to the input terminal 20 for supplying power to the control module 23 according to the DC power provided by the photovoltaic module,
the control module 23 calculates an approximate short-circuit current of the photovoltaic module according to the input voltage Vin of the input terminal, the capacitance value of the input capacitor Cin, and the starting voltage of the auxiliary power supply module, determines an illumination state of the photovoltaic module according to the approximate short-circuit current of the photovoltaic module, prohibits the inverter module 21 and the relay 22 from operating when the illumination state is a weak light state, and permits the inverter module 21 and the relay 23 to operate when the illumination state is a non-weak light state.
Specifically, the auxiliary power supply module 24 takes power from the input end of the photovoltaic inverter to provide a power supply voltage required by the operation of the control module 23; when the input voltage Vin of the photovoltaic inverter rises from zero to the starting voltage Vstart of the auxiliary power supply module 24, the auxiliary power supply module 24 starts to operate to supply power to the control module 23, so that the control module 23 starts to operate. For example, the auxiliary power supply module 24 outputs a supply voltage of 3.3V and 12V, respectively. When the input voltage Vin drops to the shutdown voltage Vstop of the auxiliary power supply module 24, the auxiliary power supply module 24 stops working, the power supply to the control module 23 is stopped, and the control module 23 stops running after power failure.
As an implementation manner of the present invention, when the input voltage Vin reaches the start voltage Vstart of the auxiliary power supply module 24, the auxiliary power supply module 24 supplies power to the control module 23. After the control module 23 is started and a first preset time elapses, the control module 23 acquires a first input voltage representing a current input voltage of the input terminal 20, calculates an approximate short-circuit current of the photovoltaic module according to the first input voltage, a capacitance value of the input capacitor Cin, the starting voltage Vstart, and the first preset time, and determines an illumination state of the photovoltaic module according to the approximate short-circuit current of the photovoltaic module. And comparing the approximate short-circuit current with a preset current threshold value. When the approximate short-circuit current is larger than the current threshold, the illumination intensity is large enough at the moment, and the control module 23 judges that the illumination state is a non-weak light state and allows the photovoltaic inverter to be started. When the approximate short-circuit current is smaller than the current threshold, it indicates that the current ambient illumination intensity is not strong enough, the control module 23 determines that the illumination state is a weak light state, and at this time, if the photovoltaic inverter is started, the problem of restarting due to power failure can be met, so that the photovoltaic inverter is prohibited from being started. The current threshold represents an illumination intensity critical value when the photovoltaic inverter can be stably started.
As an implementation manner of the present invention, the control module 23 includes a sampling unit 231, a weak light detection unit 232, and a control unit 233, where the sampling unit 231 is configured to collect input and output electrical parameters of the photovoltaic inverter, where the input and output electrical parameters include electrical parameters such as input voltage, input current, output voltage, output current, and frequency, and provide the input and output electrical parameters to the weak light detection unit 232. The weak light detection unit 232 detects the illumination state of the photovoltaic module. The weak light detection unit 232 obtains the first input voltage collected by the sampling unit 231, calculates an approximate short-circuit current of the photovoltaic module according to the first input voltage, the starting voltage Vstart and a capacitance value of the input capacitor Cin, compares the approximate short-circuit current with a preset current threshold value, generates a detection signal representing that the illumination state of the photovoltaic module is a weak light state or a non-weak light state, and outputs the detection signal to the control unit 233. When the weak light detection unit 232 determines that the illumination state is the weak light state, a detection signal representing that the illumination state is the weak light state is generated, and the control unit 233 prohibits the operation of the inverter module 21 and the relay 22 according to the detection signal; when the weak light detecting unit 232 determines that the illumination state is the non-weak light state, a detection signal indicating that the illumination state is the non-weak light state is generated. The control unit 233 generates control signals for controlling the inverter module 21 and the relay 22 according to the detection signals and the input/output electrical parameters of the photovoltaic inverter, and when the illumination state is in the non-weak light state and the input/output electrical parameters (e.g., output voltage and frequency) are within a normal range, the control signals output by the control unit 233 control the relay 22 to pull in and control the inverter module 21 to invert. When the illumination state is in a low light state, the control signal output by the control unit 233 prohibits the relay 22 and the inverter module 21 from operating, and does not allow the photovoltaic inverter to start. That is, the photovoltaic inverter is allowed to start normally only when the photovoltaic inverter is in a non-low light state.
In this embodiment, the control module 23 is a software control unit, such as an MCU, mounted on the hardware main body, and the weak light detection unit 232 is implemented by software, for example. The calculation principle of the approximate short-circuit current of the photovoltaic module is explained below, referring to fig. 3, where Vstart is the starting voltage of the auxiliary power supply module 24, Vstop is the shutdown voltage of the auxiliary power supply module 24, V1 is the first input voltage, and Vmpp is the maximum power point voltage of the photovoltaic module. As long as the first input voltage V1 is less than the maximum power point voltage Vmpp of the photovoltaic device, the output current of the photovoltaic device is in a stable state, i.e. the output current is almost kept at the short-circuit current at the output voltage zero point, the output current of the photovoltaic device can be considered to be equal to the short-circuit current within the first preset time Δ T1. Within the first preset time Δ T1, the output current of the photovoltaic module is used to charge the input capacitor Cin and supply power to the auxiliary power supply module 24, that is, the output current is the sum of the charging current of the input capacitor Cin and the input current of the auxiliary power supply module 24, and the output current, that is, the approximate short-circuit current, can be obtained by the following formula:
the Isc is an approximate short-circuit current of the photovoltaic module, the C is a capacitance value of an input capacitor Cin of the photovoltaic inverter, the V1 is a first input voltage, the Vstart is a starting voltage, the Δ T1 is a first preset time, and the Iaux is an input current of the auxiliary power supply module.
When the low light state, short-circuit current is tens of milliamperes, because general current detection chip has great zero offset, zero offset current is about 100mA, and short-circuit current is difficult directly to sample through current detection chip is accurate, compares in traditional detection scheme, and this application can reduce the deviation between approximate short-circuit current that obtains and the actual short-circuit current under the low light state to about 20mA through above formula, has improved detection accuracy greatly.
The first preset time Δ T1 is determined according to the input capacitance Cin of the photovoltaic inverter and has an inverse relationship therebetween. The first preset time is in inverse proportion to the input capacitance, and the larger the input capacitance is, the smaller the first preset time is. In a preferred embodiment, the first preset time Δ T1 is less than 10 seconds.
As an embodiment of the present invention, for example, the capacitance C of the input capacitor Cin is 18mF, the starting voltage Vstart of the auxiliary power supply module 24 is 18V, the shutdown voltage Vstop is 10V, the minimum starting power of the photovoltaic inverter is 1.5W, the corresponding approximate short-circuit current limit value is 80mA, the maximum input voltage is 60V, 60 pieces/72 pieces of photovoltaic modules commonly used in the market can be accessed, and the maximum power point voltage is in the interval of 25V to 35V. The first preset time Δ T1 is set to 1s, for example, the power consumption of the auxiliary power supply module 24 is about 400mW, and the input current Iaux of the auxiliary power supply module 10 is approximately 20mA within the first preset time T1. The maximum approximate short-circuit current that can be accurately detected by the embodiment is 146mA as can be obtained from the formula (1), and the average output power of the photovoltaic module at the first preset time Δ T1 is 3.3W.
As an implementation manner of the invention, when the photovoltaic inverter is judged to be in the low light state, the photovoltaic inverter can be allowed to operate after delaying the second preset time, so as to avoid frequent start and stop of the photovoltaic inverter. When the illumination state is a low light state, after a second preset time, the control module 23 allows the inverter module 21 and the relay 22 to operate. After the low-light state is determined, after a second preset time, the low-light detection unit 232 outputs a detection signal representing a non-low-light state, the control unit 233 allows the inversion module 21 and the relay 22 to operate, and if other operation conditions of the current photovoltaic inverter are met, the photovoltaic inverter is started and starts to work. The second preset time is preferably 5 to 20 minutes, for example, so that the time period of frequent startup and shutdown in a low-light state can be avoided.
Fig. 4 is a graph showing a relationship between an input voltage Vin and time in a starting process of the photovoltaic inverter in a low light state according to the embodiment of the invention. At an initial stage, because the illumination intensity is weak, the input voltage Vin of the photovoltaic inverter oscillates repeatedly between the starting voltage Vstart and the shutdown voltage Vstop, at this time, the auxiliary power supply module 24 does not supply power to the control module 23, and the control module 23 does not work. At the time of T1, the input voltage Vin does not drop any more, the auxiliary power supply module 24 starts to supply power to the control module 23, the control module 23 starts to work, after the first preset time T1 elapses, the input voltage Vin rises to the first input voltage V1, at this time, an approximate short-circuit current is calculated and compared with a current threshold, and since the approximate short-circuit current is smaller than the current threshold, it is determined that the current illumination state is a low-light state, the control module 23 prohibits the operation of the inverter module 21 and the relay 22, that is, prohibits the start of the photovoltaic inverter. After the second preset time Δ T2 is delayed, the inverter module 21 and the relay 22 are allowed to operate, that is, the photovoltaic inverter is allowed to start.
Fig. 5 is a graph of input voltage versus time during startup of a photovoltaic inverter according to an embodiment of the present invention in a non-dim light state. As shown in fig. 5, at time T1, the input voltage Vin rises to the start voltage Vstart and does not drop, the control module 23 starts, and after a first preset time T1, the input voltage Vin rises to the first input voltage V1, and at this time, since the approximate short-circuit current is greater than the current threshold, it is determined that the current illumination state is a non-weak light state, and the control module 23 allows the inverter module 21 and the relay 22 to operate, i.e., allows the photovoltaic inverter to start.
Fig. 6 is a flowchart illustrating a start control method of the photovoltaic inverter according to the present invention. The invention also provides a starting control method of the photovoltaic inverter, which can avoid the frequent starting and stopping of the photovoltaic inverter in a low-light state, and comprises the following steps:
s601, calculating to obtain an approximate short-circuit current of the photovoltaic module according to the input voltage of the input end of the photovoltaic inverter, the capacitance value of the input capacitor and the starting voltage of the auxiliary power supply module;
s602, judging the illumination state of the photovoltaic module according to the approximate short-circuit current of the photovoltaic module, prohibiting the operation of the inversion module and the relay when the illumination state is a weak light state, and allowing the operation of the inversion module and the relay when the illumination state is a non-weak light state.
As an implementation manner of the present invention, fig. 7 is a schematic flowchart of a start control method of a photovoltaic inverter according to the present invention, where the start control method specifically includes:
s701, when the input voltage of the photovoltaic inverter reaches the starting voltage of the auxiliary power supply module, starting the auxiliary power supply module, and supplying power to the control module to start the control module;
specifically, in an initial stage, the input voltage of the photovoltaic inverter rises linearly, and when the input voltage rises to the starting voltage of the auxiliary power supply module, the auxiliary power supply module starts to work to supply power to the control module, and the control module starts.
S702, after the control module is started and first preset time passes, collecting the current input voltage of the photovoltaic inverter to obtain a first input voltage;
s703, calculating to obtain an approximate short-circuit current according to the first input voltage, the starting voltage, the capacitance value of the input capacitor of the photovoltaic inverter and a first preset time;
the approximate short circuit current can be obtained by the following equation:
the Isc is an approximate short-circuit current of the photovoltaic module, the C is a capacitance value of an input capacitor Cin of the photovoltaic inverter, the V1 is a first input voltage, the Vstart is a starting voltage, the Δ T1 is a first preset time, and the Iaux is an input current of the auxiliary power supply module.
S704, judging whether the approximate short-circuit current is larger than a preset current threshold, if so, executing a step S705, otherwise, executing a step S706;
s705, judging that the light is not in a weak light state, and allowing the inverter module and the relay to operate;
and S706, judging the state to be in a low-light state, and allowing the inverter module and the relay to operate after a second preset time.
In summary, the invention acquires the input voltage of the photovoltaic inverter, calculates the approximate short-circuit current of the photovoltaic module according to the input voltage, the capacitance value of the input capacitor of the photovoltaic inverter and the starting voltage of the auxiliary power supply module, judges the illumination intensity of the photovoltaic module according to the approximate short-circuit current, prohibits the starting of the photovoltaic inverter if the illumination intensity of the current environment is in a low light state, and permits the starting of the photovoltaic inverter after a certain time. The starting method avoids the time period of frequent startup and shutdown in the low-light state, effectively reduces the frequency of frequent startup and shutdown of the photovoltaic inverter in the low-light state, prolongs the service life of the photovoltaic inverter, simultaneously does not need to increase hardware circuits to detect the illumination intensity, and reduces the cost.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
Claims (9)
1. A photovoltaic inverter, comprising:
the input end is used for connecting the photovoltaic module and receiving direct current electric energy provided by the photovoltaic module;
the inversion module is connected with the input end, comprises an input capacitor and an inversion unit and is used for inverting the direct current electric energy provided by the photovoltaic module into alternating current electric energy;
the relay is connected between the output ends of the inversion module and the photovoltaic inverter and is used for controlling the connection between the inversion module and a power grid;
the control module is respectively connected with the inversion module and the relay and is used for controlling the operation states of the inversion module and the relay;
the auxiliary power supply module is connected with the input end and supplies power to the control module according to the direct current electric energy provided by the photovoltaic module;
the control module calculates to obtain an approximate short-circuit current of the photovoltaic module according to the input voltage of the input end, the capacitance value of the input capacitor and the starting voltage of the auxiliary power supply module, judges the illumination state of the photovoltaic module according to the approximate short-circuit current of the photovoltaic module and a preset current threshold, judges the illumination state to be a weak light state when the approximate short-circuit current is smaller than the current threshold, prohibits the inverter module and the relay from running, judges the illumination state to be a non-weak light state when the approximate short-circuit current is larger than the current threshold, and permits the inverter module and the relay to run.
2. The photovoltaic inverter of claim 1, wherein the auxiliary power module supplies power to the control module when the input voltage reaches a starting voltage of the auxiliary power module; the control module is started and acquires a first input voltage representing the current input voltage of the input end after a first preset time, calculates an approximate short-circuit current of the photovoltaic module according to the first input voltage, the capacitance value of the input capacitor, the starting voltage and the first preset time, and judges the illumination state of the photovoltaic module according to the approximate short-circuit current of the photovoltaic module.
3. The photovoltaic inverter of claim 2, wherein the approximate short circuit current of the photovoltaic module is calculated by the formula:
the method includes the steps of obtaining an input voltage, obtaining a start voltage, obtaining a Δ T1, and obtaining an input current of an auxiliary power supply module, wherein Isc is an approximate short-circuit current of a photovoltaic module, C is a capacitance value of an input capacitor of a photovoltaic inverter, V1 is a first input voltage, Vstart is the start voltage, Δ T1 is a first preset time, and Iaux is the input current of the auxiliary power supply module.
4. The pv inverter of claim 3 wherein the first predetermined time is inversely related to a capacitance of the input capacitor, and wherein the larger the capacitance of the input capacitor, the smaller the first predetermined time.
5. The photovoltaic inverter of claim 2, wherein the control module comprises:
the sampling unit is used for collecting input and output electrical parameters of the photovoltaic inverter, and the input and output electrical parameters comprise input voltage;
the weak light detection unit is used for detecting the illumination state of the photovoltaic module, acquiring a first input voltage acquired by the sampling unit after a first preset time passes after the control module is started, calculating to obtain an approximate short-circuit current of the photovoltaic module according to the first input voltage, the capacitance value of the input capacitor, the starting voltage and the first preset time, and comparing the approximate short-circuit current with a preset current threshold value to generate a detection signal representing that the illumination state of the photovoltaic module is a weak light state or a non-weak light state;
and the control unit controls the operation states of the inversion module and the relay according to the detection signal and the input and output electrical parameters, prohibits the operation of the inversion module and the relay when the detection signal is characterized to be in a weak light state, and controls the inversion module and the relay to start to operate when the detection signal is characterized to be in a non-weak light state and the input and output electrical parameters are within a normal range.
6. The pv inverter of claim 2 wherein the control module allows the inverter module and the relay to operate after a second predetermined time when the lighting condition is a low light condition.
7. The photovoltaic inverter of claim 6, wherein the second preset time is set to 5 to 20 minutes.
8. A start-up control method of a photovoltaic inverter according to any one of claims 1 to 7, characterized by comprising:
calculating to obtain the approximate short-circuit current of the photovoltaic module according to the input voltage of the input end of the photovoltaic inverter, the capacitance value of the input capacitor and the starting voltage of the auxiliary power supply module;
judging the illumination state of the photovoltaic module according to the approximate short-circuit current of the photovoltaic module and a preset current threshold, judging the illumination state to be a weak light state when the approximate short-circuit current is smaller than the current threshold, forbidding the inversion module and the relay to operate, and judging the illumination state to be a non-weak light state when the approximate short-circuit current is larger than the current threshold, and allowing the inversion module and the relay to operate.
9. A method of controlling startup of a photovoltaic inverter as set forth in claim 8, characterized in that the method includes:
when the input voltage reaches the starting voltage of the auxiliary power supply module and the auxiliary power supply module is stably started, the auxiliary power supply module supplies power to the control module;
the control module is started and acquires a first input voltage representing the current input voltage of the input end after a first preset time, calculates an approximate short-circuit current of the photovoltaic module according to the first input voltage, the capacitance value of the input capacitor, the starting voltage and the first preset time, and judges the illumination state of the photovoltaic module according to the approximate short-circuit current of the photovoltaic module.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111291275.1A CN113746314B (en) | 2021-11-03 | 2021-11-03 | Photovoltaic inverter and starting control method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111291275.1A CN113746314B (en) | 2021-11-03 | 2021-11-03 | Photovoltaic inverter and starting control method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113746314A CN113746314A (en) | 2021-12-03 |
| CN113746314B true CN113746314B (en) | 2022-02-22 |
Family
ID=78727274
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111291275.1A Active CN113746314B (en) | 2021-11-03 | 2021-11-03 | Photovoltaic inverter and starting control method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113746314B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114019242B (en) * | 2022-01-06 | 2022-03-22 | 杭州禾迈电力电子股份有限公司 | Method and device for detecting insulation impedance of direct current side of photovoltaic inverter |
| CN115632389B (en) * | 2022-12-22 | 2023-03-14 | 杭州禾迈电力电子股份有限公司 | Shutoff device, control method thereof and photovoltaic power generation system |
| CN116505739B (en) * | 2023-06-28 | 2023-09-19 | 新华三技术有限公司 | Inverter, working condition detection method and device |
| CN116885964B (en) * | 2023-09-06 | 2023-12-05 | 浙江华昱欣科技有限公司 | Control method and device of photovoltaic inverter, electronic device and storage medium |
| CN117081358B (en) * | 2023-10-07 | 2024-07-02 | 江苏悟飞能源科技有限公司 | Single-phase cascading photovoltaic inverter and processing technology thereof |
| CN117937626B (en) * | 2024-01-23 | 2024-08-23 | 山东华电节能技术有限公司 | Multi-dimensional-based photovoltaic power station energy-saving control method and system |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4996577A (en) * | 1984-01-23 | 1991-02-26 | International Rectifier Corporation | Photovoltaic isolator and process of manufacture thereof |
| CN102843022A (en) * | 2011-06-23 | 2012-12-26 | 深圳市汇川技术股份有限公司 | System and method for suppressing repeat start of photovoltaic inverter |
| CN103095117A (en) * | 2011-11-07 | 2013-05-08 | 索尼公司 | Power Supply Apparatus, Power Controlling System And Starting Method For Electric Apparatus |
| CN104767482A (en) * | 2014-01-02 | 2015-07-08 | 上海岩芯电子科技有限公司 | Method for diagnosing aging and short circuit of photovoltaic module online |
| CN106774606A (en) * | 2016-11-28 | 2017-05-31 | 国家电网公司 | A kind of global MPPT method and apparatus under uneven illumination is even |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9785172B2 (en) * | 2012-06-13 | 2017-10-10 | Indian Institue Of Technology Bombay | Switched capacitor DC-DC converter based distributed maximum power point tracking of partially shaded photovoltaic arrays |
| US20150208469A1 (en) * | 2013-04-17 | 2015-07-23 | William P. Coetzee | Illumination device control systems and methods |
-
2021
- 2021-11-03 CN CN202111291275.1A patent/CN113746314B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4996577A (en) * | 1984-01-23 | 1991-02-26 | International Rectifier Corporation | Photovoltaic isolator and process of manufacture thereof |
| CN102843022A (en) * | 2011-06-23 | 2012-12-26 | 深圳市汇川技术股份有限公司 | System and method for suppressing repeat start of photovoltaic inverter |
| CN103095117A (en) * | 2011-11-07 | 2013-05-08 | 索尼公司 | Power Supply Apparatus, Power Controlling System And Starting Method For Electric Apparatus |
| CN104767482A (en) * | 2014-01-02 | 2015-07-08 | 上海岩芯电子科技有限公司 | Method for diagnosing aging and short circuit of photovoltaic module online |
| CN106774606A (en) * | 2016-11-28 | 2017-05-31 | 国家电网公司 | A kind of global MPPT method and apparatus under uneven illumination is even |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113746314A (en) | 2021-12-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113746314B (en) | Photovoltaic inverter and starting control method | |
| US9209737B2 (en) | Power converter | |
| JP6741169B2 (en) | Power supply device, power control device, power supply device relay determination method | |
| US9077201B2 (en) | Uninterruptible power supply device | |
| EP3624333B1 (en) | Shutdown method for photovoltaic module | |
| US10320226B2 (en) | Solar photovoltaic generation device | |
| WO2022166931A1 (en) | Power optimizer having short circuit protection, and photovoltaic power generation system | |
| EP2653877B1 (en) | Method and device for detecting state of overcurrent protector for battery | |
| CN115085367A (en) | Island detection method and device | |
| CN113904422A (en) | Energy storage inverter and energy storage inverter system | |
| CN217035747U (en) | Wake-up detection circuit, battery management system and battery pack | |
| KR20180110586A (en) | Power supply apparatus with soft―start and protection | |
| CN112994055B (en) | Storage medium, photovoltaic power generation system and control method thereof | |
| JP6738263B2 (en) | Insulation resistance inspection device, power converter, and insulation resistance measuring method | |
| CN1126224C (en) | Charging and discharging control circuit and charging type power supply device | |
| JP5973144B2 (en) | Distributed power supply apparatus, control program thereof, and control method thereof | |
| JP7333255B2 (en) | Vehicle system control method and vehicle system | |
| CN221978801U (en) | With multipath relay photovoltaic inverter mechanism of (a) | |
| CN114865685A (en) | Quick turn-off system and control method thereof | |
| EP4266524A1 (en) | Droop control in a dc operated system | |
| CN112924855A (en) | Grid-connected relay circuit | |
| CN114204522B (en) | Protection method and protection system for inverter direct current bus and air conditioner | |
| JP7363858B2 (en) | power conditioner | |
| US20240275159A1 (en) | Shutdown device control method and apparatus, and shutdown device | |
| CN116643137A (en) | Power converter and boosting unit failure detection method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |