CN106849179B - Photovoltaic power generation control method and photovoltaic power station - Google Patents
Photovoltaic power generation control method and photovoltaic power station Download PDFInfo
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Abstract
The application discloses photovoltaic power generation control method and photovoltaic power station, the photovoltaic power generation control method is applied to the photovoltaic power station, the photovoltaic power station comprises a photovoltaic module, a photovoltaic inverter, a shunt power supply device and a load, wherein the direct current side of the photovoltaic inverter is connected with the photovoltaic module and the alternating current side of the photovoltaic inverter, and the input side of the shunt power supply device is connected with the photovoltaic module and the output side of the shunt power supply device is connected with the load. The photovoltaic power generation control method includes: after the photovoltaic inverter is connected to the grid and operates, judging whether the output power of the photovoltaic inverter reaches a power limiting value or not, wherein the photovoltaic inverter is defaulted to work in an MPPT mode after being connected to the grid; when the power limit value is reached, the shunt power supply device is started until the output power of the photovoltaic inverter is smaller than the first threshold value, and the shunt power supply device is closed, so that energy waste when the photovoltaic inverter operates in the power limit mode is avoided, the utilization rate of photovoltaic energy is improved, and overhigh voltage of the direct current side of the photovoltaic inverter is prevented.
Description
Technical Field
The invention relates to the technical field of photovoltaic power generation, in particular to a photovoltaic power generation control method and a photovoltaic power station.
Background
The photovoltaic inverter is an important energy conversion device in a photovoltaic power station, and is used for converting direct current output by a photovoltaic module into alternating current and then sending the alternating current to a power grid, as shown in fig. 1.
In recent years, photovoltaic power stations in different areas adopt a design idea that the ratio of the capacity of a photovoltaic module to the capacity of a photovoltaic inverter is greater than 1 so as to achieve the purposes of improving the operating efficiency of the photovoltaic inverter and the income of the photovoltaic power station. After the photovoltaic inverter is connected to the grid and operated, the Maximum Power Point of the photovoltaic module is quickly tracked in a Maximum Power Point Tracking (MPPT) mode under default setting, but when the energy (hereinafter referred to as photovoltaic energy) generated by the photovoltaic module is greater than the energy of the photovoltaic inverter connected to the grid, the photovoltaic inverter is required to operate at limited Power.
In order to realize the limited power operation of the photovoltaic inverter, the conventional technical means is to limit the output of the photovoltaic module by controlling the photovoltaic inverter so as to ensure that the output power of the photovoltaic inverter does not exceed the limited power value. However, this would result in a great waste of photovoltaic energy, and also raise the dc side voltage of the photovoltaic inverter, which would affect the device lifetime.
Disclosure of Invention
In view of this, the invention provides a photovoltaic power generation control method and a photovoltaic power station, so as to avoid energy waste when a photovoltaic inverter operates at a limited power, improve the utilization rate of photovoltaic energy, and prevent the direct-current side voltage of the photovoltaic inverter from being too high.
A photovoltaic power generation control method is applied to a photovoltaic power station, the photovoltaic power station comprises a photovoltaic assembly, a photovoltaic inverter, a shunt power supply device and a constant load, wherein: the direct current side of the photovoltaic inverter is connected with a photovoltaic module, and the alternating current side of the photovoltaic inverter is connected with a grid; the input side of the shunt power supply device is connected with the photovoltaic module, and the output side of the shunt power supply device is connected with the constant load;
the photovoltaic power generation control method includes:
after the photovoltaic inverter is connected to the grid and operates, judging whether the output power of the photovoltaic inverter reaches a power limiting value or not, wherein the photovoltaic inverter is defaulted to work in an MPPT mode after being connected to the grid;
and when the output power of the photovoltaic inverter reaches the power limit value, starting the shunt power supply device, and closing the shunt power supply device until the output power of the photovoltaic inverter is smaller than a first threshold value.
Wherein the first threshold is a difference between the power limit value and the power required by the constant load.
A photovoltaic power generation control method is applied to a photovoltaic power station, the photovoltaic power station comprises a photovoltaic assembly, a photovoltaic inverter, a shunt power supply device and a variable load, wherein: the direct current side of the photovoltaic inverter is connected with a photovoltaic module, and the alternating current side of the photovoltaic inverter is connected with a grid; the input side of the shunt power supply device is connected with the photovoltaic module, and the output side of the shunt power supply device is connected with the variable load;
the photovoltaic power generation control method includes:
after the photovoltaic inverter is connected to the grid and operates, judging whether the output power of the photovoltaic inverter reaches a power limiting value or not, wherein the photovoltaic inverter is defaulted to work in an MPPT mode after being connected to the grid;
when the output power of the photovoltaic inverter reaches a power limit value, controlling the photovoltaic inverter to switch to a constant power mode, starting a shunt power supply device, and working in an MPPT mode after the shunt power supply device is started;
and under the constant power mode, judging whether the output power of the shunt power supply device is smaller than a second threshold value, if so, closing the shunt power supply device, and controlling the photovoltaic inverter to switch back to the MPPT mode.
Wherein the second threshold is zero.
Optionally, before the starting of the shunt power supply device, the method further includes: and judging that the duration of the output power of the photovoltaic inverter reaching the power limiting value exceeds a preset value.
Optionally, before the grid-connected operation of the photovoltaic inverter, the method further includes: judging whether the photovoltaic power station and/or the power grid are in a fault or maintenance state, and if so, starting a shunt power supply device; if not, controlling the photovoltaic inverter to operate in a grid-connected mode when the photovoltaic inverter is started and meets grid-connected conditions.
A photovoltaic power plant comprising a photovoltaic module, a photovoltaic inverter, a split power supply apparatus, a constant load and a control system, wherein:
the direct current side of the photovoltaic inverter is connected with a photovoltaic module, and the alternating current side of the photovoltaic inverter is connected with a grid;
the input side of the shunt power supply device is connected with the photovoltaic module, and the output side of the shunt power supply device is connected with the constant load;
the control system is used for judging whether the output power of the photovoltaic inverter reaches a power limit value or not after the photovoltaic inverter is connected to the grid and operates, wherein the photovoltaic inverter is defaulted to work in an MPPT mode after being connected to the grid; and when the output power of the photovoltaic inverter reaches the power limit value, starting the shunt power supply device, and closing the shunt power supply device until the output power of the photovoltaic inverter is smaller than a first threshold value.
A photovoltaic power plant comprising a photovoltaic module, a photovoltaic inverter, a split power supply apparatus, a variable load and a control system, wherein:
the direct current side of the photovoltaic inverter is connected with a photovoltaic module, and the alternating current side of the photovoltaic inverter is connected with a grid;
the input side of the shunt power supply device is connected with the photovoltaic module, and the output side of the shunt power supply device is connected with the variable load;
the control system is used for judging whether the output power of the photovoltaic inverter reaches a power limit value or not after the photovoltaic inverter is connected to the grid and operates, wherein the photovoltaic inverter is defaulted to work in an MPPT mode after being connected to the grid; when the output power of the photovoltaic inverter reaches a power limit value, controlling the photovoltaic inverter to switch to a constant power mode, starting a shunt power supply device, and working in an MPPT mode after the shunt power supply device is started; and under the constant power mode, judging whether the output power of the shunt power supply device is smaller than a second threshold value, if so, closing the shunt power supply device, and controlling the photovoltaic inverter to switch back to the MPPT mode.
Optionally, before the shunt power supply device is started, the control unit is further configured to determine that a duration of the obtained photovoltaic inverter output power reaching the power limit value exceeds a preset value.
Optionally, before the grid-connected operation of the photovoltaic inverter, the control unit is further configured to determine whether the photovoltaic power station and/or the power grid is in a fault or a maintenance state, and if so, start the shunt power supply device; if not, controlling the photovoltaic inverter to operate in a grid-connected mode when the photovoltaic inverter is started and meets grid-connected conditions.
According to the technical scheme, when the output power of the photovoltaic inverter reaches the power limiting value, the shunt power supply device is started, and the part of photovoltaic energy which needs to be limited to be output originally is converted and then is supplied to the load, so that the power limiting operation of the photovoltaic inverter is ensured, the photovoltaic energy waste is restrained, and the condition that the voltage on the direct current side of the photovoltaic inverter is overhigh is avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a photovoltaic power station disclosed in the prior art;
FIG. 2 is a schematic structural diagram of a photovoltaic power plant according to an embodiment of the present invention;
FIG. 3 is a flowchart of a photovoltaic power generation control method according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of another photovoltaic power plant disclosed in the embodiment of the present invention;
fig. 5 is a flowchart of another photovoltaic power generation control method disclosed in the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The first embodiment is as follows:
in order to avoid energy waste when the photovoltaic inverter operates at limited power, improve the utilization rate of photovoltaic energy and prevent overhigh voltage of the direct current side of the photovoltaic inverter, the embodiment of the invention discloses a photovoltaic power generation control method applied to a photovoltaic power station shown in fig. 2.
The photovoltaic power plant comprises a photovoltaic module 100, a photovoltaic inverter 200, a shunt power supply device 300 and a constant load 400, wherein: the direct current side of the photovoltaic inverter 200 is connected with the photovoltaic module 100, and the alternating current side is connected with the grid; the input side of the shunt power supply device 300 is connected to the photovoltaic module 100, and the output side thereof is connected to the constant load 400.
The constant load means a load having a constant impedance, and the load may be a dc load or an ac load. When the constant load 400 is a DC load with constant impedance, the shunt power supply device 300 employs a DC/DC converter; when the constant load 400 is an alternating current load with a constant impedance, the shunt power supply device 300 employs a DC/AC converter.
As shown in fig. 3, the photovoltaic power generation control method disclosed in the present embodiment includes:
step S01: after the photovoltaic inverter 200 is operated in a grid-connected mode, judging whether the output power of the photovoltaic inverter 200 reaches a power limiting value, wherein the photovoltaic inverter 200 is operated in an MPPT mode by default after the grid-connected mode; when the output power of the photovoltaic inverter 200 reaches the power limit value, the process proceeds to step S02; otherwise, step S01 is executed again.
Specifically, initially, the shunt power supply device 300 is in a shutdown state, and after the photovoltaic inverter 200 is started, the voltage states of the power grid and the photovoltaic module 100 are monitored in real time. When the amplitude and the frequency of the grid voltage meet the operation requirement of the photovoltaic inverter 200 and the voltage of the photovoltaic module 100 is not less than the starting voltage of the photovoltaic inverter 200, the photovoltaic inverter 200 automatically performs grid-connected operation, and the maximum power point of the photovoltaic module 100 is quickly tracked in an MPPT mode under default setting, so that the transmission of electric energy from the photovoltaic module to the grid is realized. When the output power of the pv inverter 200 reaches the predefined power limit value, the pv inverter is required to operate in the power limit, but the conventional technical means may cause the part of the pv energy whose output is limited to be wasted and may also cause the dc-side voltage of the pv inverter 200 to be too high, and based on this, the present embodiment adopts steps S02 to S04 to avoid this problem.
Step S02: the shunt power supply apparatus 300 is activated.
Specifically, when the pv inverter 200 operates in the MPPT mode, the shunt power supply device 300 is activated to separate a fixed amount of energy from all the energy generated by the pv module 100 to supply power to the constant load 400, and the greater the impedance of the constant load 400, the more the separated pv energy. Therefore, as long as the constant load 400 with the appropriate impedance is selected according to the amount of the part of the photovoltaic energy that needs to be limited to be output originally, after the constant load 400 is put into operation, the part of the photovoltaic energy that needs to be limited to be output originally can be consumed by the constant load 400, waste is avoided, and the photovoltaic inverter 200 is ensured to be in the power limiting state. Moreover, since the present embodiment does not need to limit the output of the photovoltaic module 100, the dc side voltage of the photovoltaic inverter 200 is not too high.
Step S03: judging whether the output power of the photovoltaic inverter 200 is smaller than a first threshold value, if so, entering a step S04; if not, step S03 is executed again. Wherein the optimal setting value of the first threshold is the difference between the limited power value and the power required by the constant load 400.
Step S04: the shunt power supply device 300 is turned off.
Defining the output power of the photovoltaic inverter 200, the power limiting value and the power required by the constant load 400 as Pout、PlimitAnd P400. Photovoltaic inverter 200 limited power operation means that P is converted intooutLimited to less than PlimitIn the range of (1), in the case of limited power, if PoutReduce to Pout+P400＜PlimitTo such an extent that the constant load 400 is cut off, so that PoutLifting P400After that, the air conditioner is started to work,the power limit requirement can still be met. Therefore, on the premise of meeting the power limit requirement, in order to ensure that all the photovoltaic energy is preferentially transmitted to the power grid after being converted, the embodiment is implemented at Pout＜Plimit-P400At this time, the shunt power supply device 300 is turned off to cut off the constant load 400.
Alternatively, the embodiment may select Pout＜P1(P1Less than Plimit-P400) The shunt power supply 300 is turned off, but this causes the inverter grid-connected power generation energy to be reduced, so the present embodiment recommends Pout＜Plimit-P400As the optimum timing for turning off the shunt power supply device 300.
The inventive concept of the embodiment is as follows: when the output power of the photovoltaic inverter reaches the power limiting value, the shunt power supply device is started, and the part of photovoltaic energy which needs to be limited to be output originally is converted and then is supplied to the load, so that the power limiting operation of the photovoltaic inverter is ensured, and the photovoltaic energy waste is restrained. Moreover, since the output of the photovoltaic module is not limited in the embodiment, the situation that the voltage on the direct current side of the photovoltaic inverter is too high can not occur.
Example two:
the embodiment of the invention discloses a photovoltaic power generation control method applied to a photovoltaic power station shown in figure 4.
The photovoltaic power plant comprises a photovoltaic module 100, a photovoltaic inverter 200, a shunt power supply device 300 and a variable load 400, wherein: the direct current side of the photovoltaic inverter is connected with the photovoltaic module 100, and the alternating current side of the photovoltaic inverter is connected with the grid; the input side of the shunt power supply device 300 is connected to the photovoltaic module 100, and the output side thereof is connected to the variable load 400.
The variable load is a load having a variable impedance, and may be a dc load or an ac load. When the variable load 400 is a DC load with variable impedance, the shunt power supply device 300 employs a DC/DC converter; when the variable load 400 is an alternating current load with variable impedance, the shunt power supply device 300 employs a DC/AC converter.
As shown in fig. 5, the photovoltaic power generation control method includes:
step S01: after the photovoltaic inverter 200 is operated in a grid-connected mode, judging whether the output power of the photovoltaic inverter 200 reaches a power limiting value or not, wherein the photovoltaic inverter is operated in an MPPT mode by default after being connected in the grid; when the output power of the photovoltaic inverter 200 reaches the power limit value, the process proceeds to step S02; otherwise, step S01 is executed again.
Step S02: and controlling the photovoltaic inverter 200 to switch to the constant power mode, starting the shunt power supply device 300, and enabling the shunt power supply device 300 to work in the MPPT mode after being started.
Specifically, in the initial situation, the shunt power supply device 300 is in the shutdown state; after automatic grid-connected operation, the photovoltaic inverter 200 defaults to work in the MPPT mode, and converts all energy generated by the photovoltaic module 100 and transmits the converted energy to the power grid. After the pv inverter 200 is switched to the constant power mode (the constant power mode is that the output power of the pv inverter 200 is constant, and the constant power value is generally set to be equal to the power limit value), the pv inverter 200 separates a fixed amount of energy from all the energy generated by the pv module 100 and transmits the energy to the grid, and the remaining energy is converted by the shunt power supply device 300 and supplies power to the variable load 400, so that the pv energy is fully utilized and the waste is avoided under the condition that the limited power operation of the pv inverter 200 is ensured. Moreover, since the present embodiment does not need to limit the output of the photovoltaic module 100, the dc side voltage of the photovoltaic inverter 200 is not too high.
Step S03: in the constant power mode, it is determined whether the output power of the shunt power supply device 300 is smaller than the second threshold, if so, the process proceeds to step S04; if not, step S03 is executed again. Wherein the optimal setting value of the second threshold is zero.
Step S04: shunt power supply device 300 is turned off, and photovoltaic inverter 200 is controlled to switch back to the MPPT mode.
Since when pv inverter 200 operates in the constant power mode, shunt power supply device 300 operates in the MPPT mode, that is, shunt power supply device 300 always maintains the maximum power output, as long as it is detected that the output power of shunt power supply device 300 is less than 0, it indicates that all energy generated by pv module 100 has been completely transmitted to the power grid by pv inverter 200, and no remaining energy is converted by shunt power supply device 300 to supply power to constant load 400, so shunt power supply device 300 needs to be turned off to cut off constant load 400 at this time, and pv inverter 200 also needs to recover to operate in the MPPT mode.
Of course, the embodiment can also choose to detect that the output power of the shunt power supply device 300 is less than P2(P2> 0), but there is still a certain photovoltaic energy waste, so the present embodiment recommends the shunt power supply device 300 output power being less than 0 as the best time to execute step S04.
Obviously, the present embodiment has the same inventive concept as the previous embodiment, and the shunt power supply device is started when the output power of the photovoltaic inverter reaches the power limit value, so as to convert the portion of the photovoltaic energy that needs to be limited to be output originally and supply power to the load, thereby ensuring the power limit operation of the photovoltaic inverter and suppressing the photovoltaic energy waste. In addition, the output of the photovoltaic module is not required to be limited, so that the situation that the direct-current side voltage of the photovoltaic inverter is too high is avoided.
Optionally, before starting the shunt power supply device, the photovoltaic power generation control method disclosed in any of the embodiments further includes: and judging that the duration of the output power of the photovoltaic inverter reaching the power limiting value exceeds a preset value. When the duration that the output power of the photovoltaic inverter reaches the power limit value exceeds the preset value, the photovoltaic inverter can be considered to be stably operated, and the shunt power supply device 300 is started at the moment, so that the shunt power supply device 300 can be prevented from being frequently started due to frequent fluctuation of the output power of the photovoltaic inverter near the power limit value.
Optionally, before the grid-connected operation of the photovoltaic inverter, the photovoltaic power generation control method disclosed in any of the embodiments further includes: judging whether the photovoltaic power station and/or the power grid are in a fault or maintenance state, and if so, starting a shunt power supply device; if not, when the photovoltaic inverter is started and meets the grid-connected condition, the photovoltaic inverter is controlled to operate in a grid-connected mode, and therefore photovoltaic energy is prevented from being wasted when a photovoltaic power station and/or a power grid breaks down or is overhauled.
Example three:
the embodiment of the invention discloses a photovoltaic power station, which comprises a photovoltaic component, a photovoltaic inverter, a shunt power supply device, a constant load and a control system (the specific structure of the photovoltaic power station can refer to fig. 2, and the control system is not shown in fig. 2), wherein:
the direct current side of the photovoltaic inverter is connected with a photovoltaic module, and the alternating current side of the photovoltaic inverter is connected with a grid;
the input side of the shunt power supply device is connected with the photovoltaic module, and the output side of the shunt power supply device is connected with the constant load;
the control system is used for judging whether the output power of the photovoltaic inverter reaches a power limit value or not after the photovoltaic inverter is connected to the grid and operates, wherein the photovoltaic inverter is defaulted to work in an MPPT mode after being connected to the grid; and when the output power of the photovoltaic inverter reaches the power limit value, starting the shunt power supply device, and closing the shunt power supply device until the output power of the photovoltaic inverter is smaller than a first threshold value. Wherein the optimal setting value of the first threshold is the difference between the limited power value and the power required by the constant load 400.
The constant load is a direct current load with constant impedance, and the shunt power supply device is a DC/DC converter; or, the constant load is an alternating current load with constant impedance, and the shunt power supply device is a DC/AC converter.
The embodiment of the present invention further discloses another photovoltaic power station, which includes a photovoltaic module, a photovoltaic inverter, a shunt power supply device, a variable load, and a control system (the specific structure of the photovoltaic power station may refer to fig. 4, and the control system is not shown in fig. 4), wherein:
the direct current side of the photovoltaic inverter is connected with a photovoltaic module, and the alternating current side of the photovoltaic inverter is connected with a grid;
the input side of the shunt power supply device is connected with the photovoltaic module, and the output side of the shunt power supply device is connected with the variable load;
the control system is used for judging whether the output power of the photovoltaic inverter reaches a power limit value or not after the photovoltaic inverter is connected to the grid and operates, wherein the photovoltaic inverter is defaulted to work in an MPPT mode after being connected to the grid; when the output power of the photovoltaic inverter reaches a power limit value, controlling the photovoltaic inverter to switch to a constant power mode, starting a shunt power supply device, and working in an MPPT mode after the shunt power supply device is started; and under the constant power mode, judging whether the output power of the shunt power supply device is smaller than a second threshold value, if so, closing the shunt power supply device, and controlling the photovoltaic inverter to switch back to the MPPT mode. Wherein the optimal setting value of the second threshold is zero.
The variable load is a direct current load with variable impedance, and the shunt power supply device is a DC/DC converter; or, the variable load is an alternating current load with variable impedance, and the shunt power supply device is a DC/AC converter.
In addition, in any of the photovoltaic power plants disclosed above, the control system may employ only one processor, or may employ a plurality of processors, and the processors exchange data with each other. Moreover, the processor can be integrated inside the control system of the photovoltaic inverter or the shunt power supply device, and can also be independently arranged outside the control system of the photovoltaic inverter and the shunt power supply device.
In any of the above-disclosed photovoltaic power stations, before the shunt power supply device is started, the control unit is further configured to determine that a duration of time for which the obtained output power of the photovoltaic inverter reaches the power limit value exceeds a preset value.
In any of the above-disclosed photovoltaic power stations, before the grid-connected operation of the photovoltaic inverter, the control unit is further configured to determine whether the photovoltaic power station and/or the power grid is in a fault or a maintenance state, and if so, start the shunt power supply device; if not, controlling the photovoltaic inverter to operate in a grid-connected mode when the photovoltaic inverter is started and meets grid-connected conditions.
In summary, when the output power of the photovoltaic inverter reaches the power limit value, the shunt power supply device is started, and the part of the photovoltaic energy which needs to be limited to be output originally is converted and then is supplied to the load, so that the power limit operation of the photovoltaic inverter is ensured, the photovoltaic energy waste is restrained, and the situation that the voltage on the direct current side of the photovoltaic inverter is too high is avoided.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the photovoltaic power station disclosed by the embodiment, the photovoltaic power station corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the embodiments. Thus, the present embodiments are not intended to be limited to the embodiments shown herein but are to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
1. A photovoltaic power generation control method is applied to a photovoltaic power station, and is characterized in that the photovoltaic power station comprises a photovoltaic assembly, a photovoltaic inverter, a shunt power supply device and a constant load, wherein: the direct current side of the photovoltaic inverter is connected with a photovoltaic module, and the alternating current side of the photovoltaic inverter is connected with a grid; the input side of the shunt power supply device is connected with the photovoltaic module, and the output side of the shunt power supply device is connected with the constant load;
the photovoltaic power generation control method includes:
under the initial condition, the shunt power supply device is in a shutdown state, the voltage states of a power grid and the photovoltaic module are monitored in real time after the photovoltaic inverter is started, and when the amplitude and the frequency of the voltage of the power grid meet the operation requirements of the photovoltaic inverter and the voltage of the photovoltaic module is not less than the starting voltage of the photovoltaic inverter, the photovoltaic inverter automatically operates in a grid-connected mode;
after the photovoltaic inverter is connected to the grid and operates, judging whether the output power of the photovoltaic inverter reaches a power limiting value or not, wherein the photovoltaic inverter is defaulted to work in an MPPT mode after being connected to the grid;
when the output power of the photovoltaic inverter reaches a power limit value, starting a shunt power supply device, separating a fixed amount of energy from all energy generated by a photovoltaic module to supply power for the constant load, and when the output power of the photovoltaic inverter is smaller than a first threshold value, closing the shunt power supply device to ensure that all photovoltaic energy is converted and then preferentially transmitted to a power grid, wherein the first threshold value is the difference between the power limit value and the power required by the constant load;
after the shunt power supply device is turned off, the fixed amount of energy supplied to the constant load by the photovoltaic module is converged into the photovoltaic inverter, and the output power of the photovoltaic inverter can be improved but still meets the limited power requirement.
2. A photovoltaic power generation control method is applied to a photovoltaic power station, and is characterized in that the photovoltaic power station comprises a photovoltaic assembly, a photovoltaic inverter, a shunt power supply device and a variable load, wherein: the direct current side of the photovoltaic inverter is connected with a photovoltaic module, and the alternating current side of the photovoltaic inverter is connected with a grid; the input side of the shunt power supply device is connected with the photovoltaic module, and the output side of the shunt power supply device is connected with the variable load;
the photovoltaic power generation control method includes:
under the initial condition, the shunt power supply device is in a shutdown state, the voltage states of a power grid and the photovoltaic module are monitored in real time after the photovoltaic inverter is started, and when the amplitude and the frequency of the voltage of the power grid meet the operation requirements of the photovoltaic inverter and the voltage of the photovoltaic module is not less than the starting voltage of the photovoltaic inverter, the photovoltaic inverter automatically operates in a grid-connected mode;
after the photovoltaic inverter is connected to the grid and operates, judging whether the output power of the photovoltaic inverter reaches a power limiting value or not, wherein the photovoltaic inverter is defaulted to work in an MPPT mode after being connected to the grid;
when the output power of the photovoltaic inverter reaches a limited power value, controlling the photovoltaic inverter to be switched to a constant power mode, starting a shunt power supply device, working in an MPPT mode after the shunt power supply device is started, separating a fixed amount of energy from all energy generated by a photovoltaic assembly by the photovoltaic inverter at the moment, and transmitting the energy to a power grid, wherein the rest energy is converted by the shunt power supply device and then supplies power to the variable load;
and under the constant power mode, judging whether the output power of the shunt power supply device is smaller than a second threshold value, if so, indicating that all energy generated by the photovoltaic module is completely transmitted to the power grid by the photovoltaic inverter, and no residual energy is converted by the shunt power supply device and then supplies power to the variable load, at the moment, closing the shunt power supply device, and controlling the photovoltaic inverter to switch back to the MPPT mode, so that all photovoltaic energy is preferentially transmitted to the power grid after being converted, wherein the second threshold value is zero.
3. The photovoltaic power generation control method according to any one of claims 1 to 2, wherein before the starting of the shunt power supply device, the method further comprises: and judging that the duration of the output power of the photovoltaic inverter reaching the power limiting value exceeds a preset value.
4. The photovoltaic power generation control method according to any one of claims 1 to 2, characterized by further comprising, before grid-connected operation of the photovoltaic inverter: judging whether the photovoltaic power station and/or the power grid are in a fault or maintenance state, and if so, starting a shunt power supply device; if not, controlling the photovoltaic inverter to operate in a grid-connected mode when the photovoltaic inverter is started and meets grid-connected conditions.
5. A photovoltaic power plant, characterized by, includes photovoltaic module, photovoltaic inverter, reposition of redundant personnel power supply unit, constant load and control system, wherein:
the direct current side of the photovoltaic inverter is connected with a photovoltaic module, and the alternating current side of the photovoltaic inverter is connected with a grid;
the input side of the shunt power supply device is connected with the photovoltaic module, and the output side of the shunt power supply device is connected with the constant load;
under the initial condition, the shunt power supply device is in a shutdown state, the voltage states of a power grid and the photovoltaic module are monitored in real time after the photovoltaic inverter is started, and when the amplitude and the frequency of the voltage of the power grid meet the operation requirements of the photovoltaic inverter and the voltage of the photovoltaic module is not less than the starting voltage of the photovoltaic inverter, the photovoltaic inverter automatically performs grid-connected operation;
the control system is used for judging whether the output power of the photovoltaic inverter reaches a power limit value or not after the photovoltaic inverter is connected to the grid and operates, wherein the photovoltaic inverter is defaulted to work in an MPPT mode after being connected to the grid; when the output power of the photovoltaic inverter reaches a power limit value, starting a shunt power supply device, separating a fixed amount of energy from all energy generated by a photovoltaic module to supply power for the constant load, and when the output power of the photovoltaic inverter is smaller than a first threshold value, closing the shunt power supply device to ensure that all photovoltaic energy is converted and then preferentially transmitted to a power grid, wherein the first threshold value is the difference between the power limit value and the power required by the constant load;
after the shunt power supply device is turned off, the fixed amount of energy supplied to the constant load by the photovoltaic module is converged into the photovoltaic inverter, and the output power of the photovoltaic inverter can be improved but still meets the limited power requirement.
6. A photovoltaic power plant, comprising a photovoltaic module, a photovoltaic inverter, a split power supply unit, a variable load and a control system, wherein:
the direct current side of the photovoltaic inverter is connected with a photovoltaic module, and the alternating current side of the photovoltaic inverter is connected with a grid;
the input side of the shunt power supply device is connected with the photovoltaic module, and the output side of the shunt power supply device is connected with the variable load;
under the initial condition, the shunt power supply device is in a shutdown state, the voltage states of a power grid and the photovoltaic module are monitored in real time after the photovoltaic inverter is started, and when the amplitude and the frequency of the voltage of the power grid meet the operation requirements of the photovoltaic inverter and the voltage of the photovoltaic module is not less than the starting voltage of the photovoltaic inverter, the photovoltaic inverter automatically operates in a grid-connected mode;
the control system is used for judging whether the output power of the photovoltaic inverter reaches a power limit value or not after the photovoltaic inverter is connected to the grid and operates, wherein the photovoltaic inverter is defaulted to work in an MPPT mode after being connected to the grid; when the output power of the photovoltaic inverter reaches a limited power value, controlling the photovoltaic inverter to be switched to a constant power mode, starting a shunt power supply device, working in an MPPT mode after the shunt power supply device is started, separating a fixed amount of energy from all energy generated by a photovoltaic assembly by the photovoltaic inverter at the moment, and transmitting the energy to a power grid, wherein the rest energy is converted by the shunt power supply device and then supplies power to the variable load; and under the constant power mode, judging whether the output power of the shunt power supply device is smaller than a second threshold value, if so, indicating that all energy generated by the photovoltaic module is completely transmitted to the power grid by the photovoltaic inverter, and no residual energy is converted by the shunt power supply device and then supplies power to the variable load, at the moment, closing the shunt power supply device, controlling the photovoltaic inverter to switch back to the MPPT mode, so that all photovoltaic energy is preferentially transmitted to the power grid after being converted, and the second threshold value is zero.
7. The pv power plant of claim 5 or 6 wherein the control system is further configured to determine that the duration of time until the pv inverter output power reaches the power limit value exceeds a predetermined value before the shunt power supply means is activated.
8. The photovoltaic power plant of claim 5 or 6 wherein before the grid-connected operation of the photovoltaic inverters, the control system is further configured to determine whether the photovoltaic power plant and/or the grid are in a fault or a maintenance state, and if so, to start the shunt power supply device; if not, controlling the photovoltaic inverter to operate in a grid-connected mode when the photovoltaic inverter is started and meets grid-connected conditions.
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| CN109802426B (en) | 2018-11-14 | 2023-04-07 | 华为技术有限公司 | Photovoltaic power generation system and control method thereof |
| CN109756186B (en) * | 2018-12-26 | 2020-11-10 | 山东辰宇稀有材料科技有限公司 | Testing method for detecting and calibrating outdoor high-precision photovoltaic power station |
| CN111130105A (en) * | 2020-01-09 | 2020-05-08 | 珠海格力电器股份有限公司 | Electric equipment control method and device based on constant limit power and control equipment |
| CN111600338A (en) * | 2020-06-17 | 2020-08-28 | 阳光电源股份有限公司 | Photovoltaic system and control method thereof |
| CN114123747A (en) * | 2021-11-26 | 2022-03-01 | 航天柏克(广东)科技有限公司 | Method and device for starting impact load |
| CN116365976A (en) | 2023-03-09 | 2023-06-30 | 华能新能源股份有限公司河北分公司 | Photovoltaic power generation control method and system |
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