CN111786393B - Household photovoltaic power generation system and grid-connected point voltage control method thereof - Google Patents

Household photovoltaic power generation system and grid-connected point voltage control method thereof Download PDF

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CN111786393B
CN111786393B CN202010588673.9A CN202010588673A CN111786393B CN 111786393 B CN111786393 B CN 111786393B CN 202010588673 A CN202010588673 A CN 202010588673A CN 111786393 B CN111786393 B CN 111786393B
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China
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grid
voltage
photovoltaic
photovoltaic inverter
connected point
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CN111786393A (en
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王磊
杨少波
胡文平
曾四鸣
孟良
李泉
郭捷
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Hebei Electric Power Co Ltd
State Grid Hebei Energy Technology Service Co Ltd
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Hebei Electric Power Co Ltd
State Grid Hebei Energy Technology Service Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/48—Controlling the sharing of the in-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • 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
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)
  • Inverter Devices (AREA)

Abstract

The application belongs to the technical field of new energy power generation, and provides a household photovoltaic power generation system and a grid-connected point voltage control method thereof. The method comprises the steps that after the photovoltaic inverter is operated in a grid-connected mode, the photovoltaic inverter monitors the voltage of a grid-connected point; the photovoltaic inverter absorbs reactive power under the condition that the voltage of the grid-connected point is greater than a first threshold value; and under the condition that the reactive power absorbed by the photovoltaic inverter reaches a second threshold value and the voltage of the grid-connected point is greater than the first threshold value, adjusting the active power of the photovoltaic inverter until the voltage of the grid-connected point meets a preset condition. According to the grid-connected point voltage control method of the household photovoltaic power generation system, the grid-connected point voltage is adjusted based on the photovoltaic inverter in the household photovoltaic power generation system, when the grid-connected point voltage exceeds the preset threshold value, the grid-connected point voltage can be effectively reduced, and the frequency of the grid-connected point voltage exceeding is effectively reduced.

Description

Household photovoltaic power generation system and grid-connected point voltage control method thereof
Technical Field
The application belongs to the technical field of new energy power generation, and particularly relates to a household photovoltaic power generation system and a grid-connected point voltage control method thereof.
Background
With the development of new energy strategy and the deep consciousness of energy conservation and emission reduction in China, the household photovoltaic power generation system is installed in buildings, structures or the ground where residents belong, has the installation capacity of 30kWp or less, and is connected to a public power grid at the voltage level of 380V/220V.
Because the photovoltaic power supply is influenced by natural conditions such as illumination, temperature and climate, active power output by the household photovoltaic power generation system has high volatility, and when the household photovoltaic power generation system is connected to a power distribution network to operate, certain impact and fluctuation are brought to the power distribution network, so that the voltage of an access terminal of the power distribution network fluctuates.
At present, an automatic voltage control system is usually configured for a large photovoltaic power station, control voltage of reactive power equipment is regulated through the automatic voltage control system, the reactive power regulation equipment usually comprises a static var generator and a photovoltaic inverter, and unlike the large photovoltaic power station, a household photovoltaic power generation system is usually not configured with regulation equipment such as the static var generator, so that voltage of a grid-connected point of the household power generation system is easy to exceed the limit, impact is brought to a power distribution network, and safety risk is brought.
Disclosure of Invention
In view of this, the embodiment of the present application provides a household photovoltaic power generation system and a grid-connected point voltage control method thereof, which solve the technical problem that in the prior art, the grid-connected point voltage of the household photovoltaic power generation system is easy to exceed the limit.
In a first aspect, an embodiment of the present application provides a grid-connected point voltage control method for a household photovoltaic power generation system, where the household photovoltaic power generation system includes a photovoltaic inverter and a photovoltaic module, a direct current side of the photovoltaic inverter is connected to the photovoltaic module, and an alternating current side of the photovoltaic inverter is grid-connected;
the method comprises the following steps:
after the photovoltaic inverter is in grid-connected operation, the photovoltaic inverter monitors the voltage of a grid-connected point;
the photovoltaic inverter absorbs reactive power under the condition that the voltage of the grid-connected point is greater than a first threshold value;
and under the condition that the reactive power absorbed by the photovoltaic inverter reaches a second threshold value and the voltage of the grid-connected point is greater than the first threshold value, adjusting the active power of the photovoltaic inverter until the voltage of the grid-connected point meets a preset condition.
In one possible implementation manner of the first aspect, the adjusting the active power of the photovoltaic inverter includes:
determining a first variation function of the active power; wherein the active power decreases at a rate of change less than a third threshold;
determining a second change function corresponding to the first change function according to the correlation between the active power and the voltage of the direct current side of the photovoltaic inverter;
and regulating the voltage of the direct current side of the photovoltaic inverter according to the second change function.
In one possible implementation manner of the first aspect, after the active power of the photovoltaic inverter is adjusted, the method further includes:
controlling the photovoltaic inverter to be disconnected under the condition that the active power is smaller than a fourth threshold value;
and under the condition that the voltage of the grid-connected point is reduced to the starting cut-off voltage, controlling the photovoltaic inverter to operate grid-connected again within a first preset time.
In one possible implementation manner of the first aspect, the method further includes determining a start-up cut-off voltage according to the first threshold and a port voltage in the photovoltaic inverter offline state, where the port voltage is a preset value.
In a possible implementation manner of the first aspect, controlling the photovoltaic inverter to perform grid-connected operation again within a first preset time includes:
determining the optimal grid-connected voltage corresponding to the highest point of the conversion efficiency of the photovoltaic inverter within a preset grid-connected voltage range;
adjusting the voltage of the alternating current side of the photovoltaic inverter to the optimal grid-connected voltage;
and controlling the photovoltaic inverter to be connected to the grid again within the first preset time.
In one possible implementation manner of the first aspect, after monitoring the grid-connected point voltage, the method further includes:
and under the condition that the voltage of the grid-connected point is smaller than a fifth threshold, the photovoltaic inverter sends out reactive power until the voltage of the grid-connected point meets a preset condition, wherein the fifth threshold is smaller than the first threshold.
In one possible implementation manner of the first aspect, the method further includes:
and under the condition that the voltage of the grid-connected point meets the preset condition, controlling the photovoltaic inverter to operate according to at least one of constant voltage control mode, constant power factor control mode or constant reactive power control mode.
In a second aspect, an embodiment of the present application provides a grid-connected point voltage control device for a household photovoltaic power generation system, including:
the monitoring module is used for monitoring the voltage of a grid-connected point after the photovoltaic inverter is in grid-connected operation;
the reactive power control module is used for enabling the photovoltaic inverter to absorb reactive power under the condition that the voltage of the grid-connected point is larger than a first threshold value;
and the active power control module is used for adjusting the active power of the photovoltaic inverter under the condition that the reactive power absorbed by the photovoltaic inverter reaches a second threshold and the voltage of the grid-connected point is greater than a first threshold until the voltage of the grid-connected point meets a preset condition.
In a third aspect, an embodiment of the present application provides a grid-connected point voltage control device for a household photovoltaic power generation system, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the steps of the method according to any one of the above first aspects when executing the computer program.
In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, where a computer program is stored, where the computer program is implemented to implement the steps of the method in any one of the above first aspects when executed by a processor.
In a fifth aspect, an embodiment of the present application provides a household photovoltaic power generation system, which includes: a photovoltaic inverter, a photovoltaic module;
the direct current side of the photovoltaic inverter is connected with the photovoltaic module, and the alternating current side of the photovoltaic inverter is used for grid connection;
the photovoltaic module is used for converting the absorbed solar energy into direct current and sending the direct current to the photovoltaic inverter;
the photovoltaic inverter is used for converting direct current sent by the photovoltaic module into alternating current and executing the steps of the method according to any one of the first aspect.
The grid-connected point voltage control method for the household photovoltaic power generation system, provided by the embodiment of the application, is used for controlling the grid-connected point voltage based on the photovoltaic inverter, under the condition that the grid-connected point voltage is larger than a first threshold value, firstly, reactive power regulation is carried out through absorbing reactive power, when the absorbed reactive power reaches a second threshold value, the photovoltaic inverter cannot continuously absorb the reactive power, if the grid-connected point voltage is still larger than the first threshold value, active power regulation is carried out, the grid-connected point voltage meets a preset condition through reducing the active power, and therefore the frequency of the grid-connected point voltage exceeding the limit is effectively reduced. According to the grid-connected point voltage control method of the household photovoltaic power generation system, the grid-connected point voltage is adjusted based on the photovoltaic inverter in the household photovoltaic power generation system, when the grid-connected point voltage exceeds the preset threshold value, the grid-connected point voltage can be effectively reduced, and the frequency of the grid-connected point voltage exceeding is effectively reduced.
The beneficial effects of the second aspect to the fifth aspect can refer to the beneficial effects of the first aspect, and are not described herein again.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a household photovoltaic power generation system provided in an embodiment of the present application;
fig. 2 is a schematic flowchart of a grid-connected point voltage control method of a household photovoltaic power generation system according to an embodiment of the present application;
fig. 3 is a schematic diagram of a reactive power output range of a photovoltaic inverter according to an embodiment of the present application;
FIG. 4 is a schematic diagram of a plurality of grid-connected point voltages according to an embodiment of the present application;
fig. 5 is a schematic flowchart of a method for regulating active power of a photovoltaic inverter according to an embodiment of the present application;
fig. 6 is a schematic flowchart of a method for recovering grid connection of a photovoltaic inverter according to an embodiment of the present application;
fig. 7 is a schematic flowchart of a grid-connected point voltage control method of a household photovoltaic power generation system according to another embodiment of the present application;
fig. 8 is a simulation diagram of a grid-connected point voltage control effect according to an embodiment of the present application;
fig. 9 is a schematic structural diagram of a device for controlling a grid-connected point voltage of a photovoltaic power generation system for a user according to an embodiment of the present application;
fig. 10 is a schematic diagram of a grid-connected point voltage control device of a household photovoltaic power generation system according to an embodiment of the present application.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
Reference throughout this specification to "one embodiment" or "some embodiments," or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," or the like, in various places throughout this specification are not necessarily all referring to the same embodiment, but rather "one or more but not all embodiments" unless specifically stated otherwise. The terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless expressly specified otherwise.
Fig. 1 is a schematic structural diagram of a household photovoltaic power generation system according to an embodiment of the present disclosure. As shown in fig. 1, the household photovoltaic power generation system includes a photovoltaic module 10 and a photovoltaic inverter 20;
wherein the dc side of the pv inverter 20 is connected to the pv module 10 and the ac side of the pv inverter 20 is connected to the utility grid.
In the present system, the pv inverter 20 may be a three-phase pv inverter suitable for a three-phase system, or may be a single-phase pv inverter suitable only for a single-phase system.
The photovoltaic inverter 10 can realize automatic grid connection of a household photovoltaic system.
For example, after the pv inverter 20 is started, the voltage of the grid-connected point and the output voltage of the pv module 10 are monitored in real time, and when the amplitude and the frequency of the voltage of the grid-connected point meet the operation requirement of the pv inverter 20 and the output voltage of the pv module 10 is not less than the starting voltage of the pv inverter 20, the pv inverter 20 will automatically perform grid-connected operation.
After the photovoltaic inverter 20 is started, the Maximum Power Point of the photovoltaic module 10 is quickly tracked in a Maximum Power Point Tracking (MPPT) mode, the direct current output by the photovoltaic module 10 is converted into alternating current, and the alternating current is provided to a public Power grid, so that the transmission of electric energy from the photovoltaic module 10 to the public Power grid is realized.
Those skilled in the art will appreciate that fig. 1 is merely an example of a household photovoltaic power generation system, and does not constitute a limitation of a household photovoltaic power generation system, and may include more or less components than those shown, such as a battery.
The photovoltaic module 10 is easily out of limit due to the influence of natural conditions such as illumination, temperature and climate and line impedance, thereby causing impact on the utility grid.
Therefore, it is urgently needed to provide a grid-connected point voltage control method based on a household photovoltaic power generation system, so as to solve the technical problem that the grid-connected point voltage of the household photovoltaic power generation system is easy to exceed the limit in the prior art.
The following describes the technical solutions of the present application and how to solve the above technical problems with specific embodiments. It is worth mentioning that the specific embodiments listed below may be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.
Fig. 2 is a schematic flowchart of a method for controlling a grid-connected point voltage of a household photovoltaic power generation system according to an embodiment of the present application, where the method for controlling a grid-connected point voltage of a household photovoltaic power generation system is applicable to the household photovoltaic power generation system shown in fig. 1, an execution subject of the embodiment is a photovoltaic inverter shown in fig. 1, and as shown in fig. 2, the method for controlling a grid-connected point voltage of a household photovoltaic power generation system includes:
and S10, monitoring the voltage of the grid-connected point by the photovoltaic inverter after the grid-connected operation of the photovoltaic inverter.
In this embodiment, after the photovoltaic inverter is operated in a grid-connected mode, the voltage of the grid-connected point is monitored, and whether the voltage of the grid-connected point meets a preset condition is judged. It can be understood that the grid-connected photovoltaic inverter is a grid-connected photovoltaic power generation system for users.
The preset condition can mean that the voltage deviation of the grid-connected point of the three-phase system is-7% to + 7% of the nominal voltage, and the allowable deviation of the voltage of the grid-connected point of the single-phase system is-10% to + 7% of the nominal voltage.
For example, if the pv inverter is a three-phase pv inverter, the selectable range of the rated voltage of the grid-connected point voltage under the preset condition may be [0.93U, 1.07U ], where U refers to the nominal voltage.
In this embodiment, when the voltage of the grid-connected point meets the preset condition, the photovoltaic inverter operates in at least one of a constant voltage control mode, a constant power factor control mode, or a constant reactive power control mode.
And S20, absorbing reactive power by the photovoltaic inverter under the condition that the voltage of the grid connection point is greater than the first threshold value.
The grid-connected point voltage is larger than the first threshold value, the voltage of the grid-connected point can be represented to be out of limit, impact is easily brought to a power distribution network, safety risks are brought, therefore, the voltage of the grid-connected point needs to be regulated and controlled, and the step aims to reduce the voltage of the grid-connected point through reactive power regulation of the photovoltaic inverter. Specifically, when the photovoltaic inverter absorbs reactive power, the voltage of the grid-connected point decreases.
Wherein the first threshold value UmaxIt may refer to 1.07U, which is a nominal voltage of 220V.
The electrical power required by a photovoltaic inverter to establish an alternating magnetic field and an induced magnetic flux is referred to as reactive power. It is understood that reactive power cannot be converted into mechanical, thermal, electrical energy, but it is also indispensable, so that in addition to active power, the photovoltaic inverter requires reactive power in the power generation system.
The reactive power includes inductive reactive power and capacitive reactive power. Since the photovoltaic inverter is described by default as the capacitive reactive power, in this embodiment, the photovoltaic inverter absorbs the reactive power specifically means that the photovoltaic inverter absorbs the capacitive reactive power.
Capacitive reactive power is understood to mean negative inductive reactive power. The photovoltaic inverter can absorb the capacitive reactive power and can also be characterized in that the photovoltaic inverter emits inductive reactive power, and specifically, the energy can be released by an inductive element arranged inside the photovoltaic inverter.
For example, the photovoltaic inverter generating the inductive reactive power may refer to adjusting a voltage phase-locked loop in the photovoltaic inverter so that the current leads the voltage, thereby generating the inductive reactive power to reduce the voltage of the grid-connected point.
And (3) monitoring the voltage of the grid-connected point in real time by the photovoltaic inverter, and stopping absorbing the reactive power if the voltage of the grid-connected point meets the preset condition in the step (10), so that the control on the voltage of the grid-connected point is realized.
And S30, under the condition that the reactive power absorbed by the photovoltaic inverter reaches a second threshold value and the voltage of the grid-connected point is greater than the first threshold value, adjusting the active power of the photovoltaic inverter until the voltage of the grid-connected point meets a preset condition.
The purpose of this step lies in, when the reactive power regulation of photovoltaic inverter can't be with grid-connected point voltage regulation to satisfy the default condition, further reduce grid-connected point voltage through adjusting photovoltaic inverter's active power.
The second threshold may be indicative of a maximum capacitive reactive power that the photovoltaic inverter can absorb, that is, a maximum inductive reactive power that the photovoltaic inverter can transmit.
In this embodiment, the second threshold may be determined by the current active power of the photovoltaic inverter and the type of the photovoltaic inverter.
The photovoltaic inverter tracks the Maximum Power Point of the photovoltaic module quickly in a Maximum Power Point Tracking (MPPT) mode, so that the active Power of the photovoltaic inverter can be determined. The type of the photovoltaic inverter can be a type A photovoltaic inverter or a type B photovoltaic inverter. The types of the photovoltaic inverter can be referred to national standards, and are not described in detail herein.
For example, please refer to fig. 3 together, wherein fig. 3 is a schematic diagram of a reactive power output range of a photovoltaic inverter according to an embodiment of the present disclosure.
As shown in fig. 3, the horizontal axis is the active power per unit value P of the photovoltaic inverter, and the vertical axis is the reactive power per unit value Q of the photovoltaic inverter, when the photovoltaic inverter is a class a photovoltaic inverter, the correlation between the reactive power and the active power of the photovoltaic inverter can be shown as a dotted line in the figure, and when the photovoltaic inverter is a class B photovoltaic inverter, the correlation between the reactive power and the active power of the photovoltaic inverter can be shown as a solid line in the figure.
That is, if the pv inverter is a class a pv inverter, the maximum value of the reactive power is always 0.33 times the active power; if the pv inverter is a class B pv inverter, the maximum value of the reactive power may be 0.33 times the active power only when the active power reaches the maximum value (the normalized value is 1).
For example, if the pv inverter of the present embodiment is a class B pv inverter, the second threshold of the pv inverter may be determined according to fig. 3.
In this embodiment, adjusting the active power of the photovoltaic inverter may refer to adjusting a voltage on a direct current side of the photovoltaic inverter, so that the photovoltaic inverter cannot quickly track a maximum power point of the photovoltaic module in the MPPT mode.
In this embodiment, the preset condition may be the preset condition in step 10, that is, the voltage of the grid-connected point is not greater than 1.07U, where U is a nominal voltage.
In order to avoid that the grid-connected point voltage exceeds the first threshold value again due to a slight fluctuation after the grid-connected point voltage is reduced, the grid-connected point voltage can be reduced by adjusting the active power of the photovoltaic inverter until the grid-connected point voltage is reduced to a target stable voltage, and the target stable voltage is smaller than the first threshold value.
For example, the target regulated voltage may be 0.98UmaxWherein, UmaxIs a first threshold.
For example, referring to fig. 4 together, fig. 4 is a schematic diagram of a plurality of grid-connected point voltages according to an embodiment of the present application. As shown in fig. 4, the abscissa of the grid-connected point voltage diagram is the grid-connected point voltage UacAnd the ordinate is the active power P of the photovoltaic inverter. When the active power is reduced, the voltage of the grid-connected point is reduced, and in fig. 4, P1，PmaxAnd P2Are all U under ideal state1、UmaxAnd U2Respectively corresponding active power.
U in FIG. 40、U1、UmaxAnd U2May refer to:
U0: the port voltage of the household photovoltaic power generation system is a fixed value when the household photovoltaic power generation system is not connected to the grid;
Umax: the upper voltage limit of the normal operation of the public network power grid, namely the first threshold value, can be 1.07U, and U is a nominal voltage;
U1: when the voltage exceeds the limit, impact is brought to a public power grid;
U2: a target stabilization voltage;
in this example, the target regulated voltage is 0.98UmaxWhen the grid-connected point voltage fluctuates in the range, the grid-connected point voltage does not need to be controlled, and the situation that the grid-connected point voltage exceeds the first threshold value again due to tiny fluctuation after being reduced is avoided.
The grid-connected point voltage control method for the household photovoltaic power generation system, provided by the embodiment of the application, is used for controlling the grid-connected point voltage based on the photovoltaic inverter, under the condition that the grid-connected point voltage is larger than a first threshold value, firstly, reactive power regulation is carried out through absorbing reactive power, when the absorbed reactive power reaches a second threshold value, the photovoltaic inverter can not continuously absorb the reactive power, if the grid-connected point voltage is still larger than the first threshold value, active power regulation is carried out, the grid-connected point voltage meets a preset condition through reducing the active power, and therefore the frequency that the grid-connected point voltage is out of limit is effectively reduced. According to the grid-connected point voltage control method of the household photovoltaic power generation system, the grid-connected point voltage is adjusted based on the photovoltaic inverter in the household photovoltaic power generation system, when the grid-connected point voltage exceeds the preset threshold value, the grid-connected point voltage can be effectively reduced, and the frequency of the grid-connected point voltage exceeding is effectively reduced.
In practical applications, the grid-connected point voltage may be greater than a maximum value (e.g., a first threshold) of the preset conditions, or may be less than a minimum value of the preset conditions, and in an exemplary case where the grid-connected point voltage is less than a fifth threshold,send out nothing And (4) working power until the voltage of the grid connection point meets the preset condition.
The fifth threshold may be a minimum value of 0.93U in the preset condition, where U is a nominal voltage.
Wherein the preset condition may be the same as the preset condition in step 10.
It is to be understood that the fifth threshold is smaller than the first threshold, and the reactive power refers to capacitive reactive power.
Through the regulation of the reactive power and the active power of the photovoltaic inverter, the voltage of a grid connection point of a household photovoltaic power generation system can be controlled to be quickly read and restored to a preset condition range under the condition that the voltage is larger than a first threshold value or lower than a fifth threshold value, and therefore the impact on a public power grid is reduced.
Fig. 5 is a schematic flow chart of a method for regulating active power of a photovoltaic inverter according to an embodiment of the present application; describing one possible implementation of regulating the photovoltaic inverter in step 30 of the embodiment in fig. 2, as shown in fig. 5, the regulating the active power of the photovoltaic inverter includes:
s301, determining a first change function of active power.
In this embodiment, the active power decreases at a rate of change smaller than the third threshold, and the first change function is used to describe a trend of change of the active power.
For example, the third threshold may be 10% installed capacity/second set by the user, i.e. active power may be reduced at a rate of change not exceeding 10% installed capacity/second.
S302, determining a second change function corresponding to the first change function according to the correlation between the active power and the voltage of the direct current side of the photovoltaic inverter.
In this embodiment, the second variation function is used to characterize the variation of the voltage on the dc side of the photovoltaic inverter.
Specifically, the change rule of the direct current side voltage of the photovoltaic inverter can be referred to when the active power is reduced at a change rate of no more than 10% installed capacity/second.
In this embodiment, the correlation between the active power and the voltage at the dc side of the photovoltaic inverter may be determined according to a power current P-V characteristic curve of the photovoltaic module.
And S303, regulating the voltage of the direct current side of the photovoltaic inverter according to the second change function.
The embodiment of the application provides a method for adjusting the active power of a photovoltaic inverter by adjusting the direct-current voltage of the photovoltaic inverter.
In practical application, when the active power of the photovoltaic inverter is too low, a user may be caused to stop transmitting power to the public power grid by the photovoltaic power generation system, at this time, the photovoltaic inverter needs to be controlled to disconnect the grid, after the voltage of the grid connection point is reduced to a preset condition, whether the requirement of re-grid connection is met is judged, and after the requirement of re-grid connection is met, grid connection is resumed, which is exemplarily described below with the embodiment shown in fig. 6.
Fig. 6 is a schematic flowchart of a method for recovering grid connection of a photovoltaic inverter according to an embodiment of the present application; described is an embodiment of a possible restoration grid connection, as shown in fig. 6, after the active power of the photovoltaic inverter is adjusted, the method further includes:
and S41, controlling the photovoltaic inverter to be disconnected under the condition that the active power is smaller than the fourth threshold value.
In this embodiment, the fourth threshold may refer to a minimum active power at which the photovoltaic inverter may transmit power to the utility grid. The fourth threshold may be a value set in advance by the user.
And S42, controlling the photovoltaic inverter to operate grid connection again within a first preset time under the condition that the grid connection point voltage is reduced to the starting cut-off voltage.
In order to avoid repeated grid connection and grid disconnection caused by sudden power rise and drop of a household photovoltaic power generation system, after the voltage of a grid connection point is reduced to a preset condition, the grid connection is not directly recovered, and after the voltage of the grid connection point is reduced to a starting cut-off voltage, the grid connection point is controlled to be connected to the grid again to operate. It is understood that the start-up cut-off voltage is less than the first threshold.
In this embodiment, the start cut-off voltage may refer to a start voltage of the photovoltaic inverter, and may also be determined according to a first threshold and a port voltage of the photovoltaic inverter in the offline state, where the port voltage is a preset value.
For example, the start-up cut-off voltage can be calculated with reference to the following equation:
U3<0.5×(Umax-U0)+U0(1)
wherein, U3To initiate the cut-off voltage, UmaxIs a first threshold value, U0Is the port voltage.
In this embodiment, controlling the photovoltaic inverter to operate grid-connected again within the first preset time may include:
step 1: and determining the optimal grid-connected voltage corresponding to the highest point of the conversion efficiency of the photovoltaic inverter within a preset grid-connected voltage range.
In this step, a plurality of candidate grid-connected voltages can be selected from a preset grid-connected voltage range, the conversion efficiency of the photovoltaic inverter under each candidate grid-connected voltage is obtained, and the candidate grid-connected voltage corresponding to the highest conversion efficiency is determined as the optimal grid-connected voltage.
It should be understood that a plurality of candidate grid-connection voltages are all less than the start-up cut-off voltage.
Step 2: and regulating the voltage of the alternating current side of the photovoltaic inverter to the optimal grid-connected voltage.
And step 3: and controlling the photovoltaic inverter to be connected to the grid again within the first preset time.
In this step, the first preset time may be set by a user, for example, 300 s.
When the active power of the photovoltaic inverter is too low, a user can stop transmitting power to a public power grid by the photovoltaic power generation system, and at the moment, the photovoltaic inverter needs to be controlled to be disconnected. According to the method for recovering the grid connection of the photovoltaic inverter, after the grid connection point voltage is judged to be reduced and the starting cut-off voltage is started, the photovoltaic inverter is controlled to be in grid connection operation again within the first preset time, and the situation that a user is in a grid disconnection state for reducing the grid connection point voltage in order to avoid the user from being in the grid disconnection state for a long time is avoided.
Fig. 7 is a schematic flowchart of a grid-connected point voltage control method of a household photovoltaic power generation system according to another embodiment of the present application; the main implementation of the method is the photovoltaic inverter of fig. 1, as shown in fig. 7, the method includes:
s501, monitoring the voltage of a grid-connected point after the grid-connected operation of the photovoltaic inverter.
S502, judging whether the current grid-connected point voltage meets a preset condition. If so, step 510 is executed, otherwise, if the grid-connected point voltage is greater than the first threshold, step 503 is executed, and if the grid-connected point voltage is less than the fifth threshold, step 509 is executed.
And S503, the photovoltaic inverter absorbs reactive power.
S504, under the condition that the reactive power absorbed by the photovoltaic inverter reaches a second threshold value and the voltage of the grid-connected point is larger than a first threshold value, the active power of the photovoltaic inverter is adjusted.
S505, determining whether the active power is smaller than a fourth threshold, if yes, executing step 507, otherwise, executing step 506.
And S505, continuously reducing the active power of the photovoltaic inverter until the voltage of the grid-connected point meets a preset condition.
And S507, controlling the photovoltaic inverter to be disconnected under the condition that the active power is smaller than a fourth threshold value.
And S508, controlling the photovoltaic inverter to operate grid connection again within a first preset time under the condition that the voltage of the grid connection point is reduced to the starting cut-off voltage.
And S509, under the condition that the voltage of the grid-connected point is smaller than a fifth threshold, the photovoltaic inverter sends out reactive power until the voltage of the grid-connected point meets a preset condition.
And S510, controlling the photovoltaic inverter to operate according to at least one mode of constant voltage control, constant power factor control or constant reactive power control mode.
The implementation and beneficial effects of each step in this embodiment can refer to the related descriptions of the above method embodiments, and are not described herein again.
For a more clear description of the embodiment, please refer to fig. 8, fig. 8 is a simulation diagram of the grid-connected point voltage control effect provided in an embodiment of the present application, fig. 8 takes a 220V single-phase household photovoltaic power generation system as an example, and a photovoltaic inverter in the household photovoltaic power generation system is a class B inverter.
As shown in FIG. 8, the abscissa in the coordinate system is timeLeft ordinate is the grid-connected point voltage UacAnd the right ordinate is the output power of the photovoltaic inverter.
Wherein, curve 1 is a voltage change curve of a grid connection point, curve 2 is an active power change curve of the photovoltaic inverter, and curve 3 is a reactive power change curve of the photovoltaic inverter.
It should be understood that the reactive power curve records the process of emitting inductive reactive power, and may also record the process of emitting capacitive reactive power. Since this embodiment describes a process of reducing the voltage of the grid-connected point, the reactive power curve in fig. 8 can be understood as the emitted inductive reactive power.
In this embodiment, the first threshold UmaxIs 235.4V, i.e. 1.07 times the nominal voltage, the target regulated voltage U2Is 0.98Umax230.7V, port voltage U when the household photovoltaic power generation system is not connected to the grid0Is 227V.
As shown in fig. 8, before the grid connection of the photovoltaic inverter, the port voltage of the photovoltaic inverter in the off-grid state is 227V, and the photovoltaic inverter is in a stable operation state.
The photovoltaic inverter is connected to the grid at 0.7s, the voltage of a grid connection point is increased, and the photovoltaic inverter monitors the voltage of the grid connection point in real time;
when the voltage of the grid-connected point reaches the first threshold 235.4V at 0.9s and exceeds the first threshold 235.4V, the user starts to absorb reactive power, specifically, inductive reactive power is emitted, and the voltage of the grid-connected point starts to decrease.
The photovoltaic inverter operates based on a maximum power tracking mode, namely the active power of the photovoltaic inverter needs to determine the maximum power according to the output voltage of the photovoltaic module, and at the moment, the active power of the photovoltaic inverter continuously rises, which is characterized by further rising of grid-connected voltage.
1.1s, the active power of the household photovoltaic power generation system reaches the maximum value of 8kW, the voltage of the grid-connected point reaches the maximum value of 245V, and then the voltage of the grid-connected point starts to decrease along with the further increase of the generated inductive reactive power;
the inductive reactive power emitted at 1.9s reaches the maximum value of 2.64kVar, and the voltage of the grid-connected point is 236V and still greater than the upper limit 235.4V. When the capacitive reactive power absorbed by the photovoltaic inverter reaches the maximum value, the voltage of a grid connection point is still larger than a first threshold value, and the active power of the photovoltaic inverter starts to be adjusted at the moment, wherein the specific characteristic is that the active power of the photovoltaic inverter is reduced, namely 2.1s, a user starts to reduce the active power of the photovoltaic inverter by using the photovoltaic power generation system;
the active power is reduced to 5.64kW in 5.05s, the voltage of a grid connection point is reduced to 230.7V, and the U meeting the target stable voltage2And the active power is not reduced at the moment, and the household photovoltaic power generation system starts to run stably.
In practical application, if the active power is limited to cause that a user stops transmitting power to a power grid by the photovoltaic power generation system, that is, the active power is smaller than a preset fourth threshold, the photovoltaic inverter is controlled to disconnect the power grid, and when the grid-connected voltage is reduced to a starting cut-off voltage, the grid-connected voltage is resumed, wherein the starting cut-off voltage meets a condition that "U3 is less than 0.5 × (Umax-U0) + U0 is 231.2V".
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.
Based on the method for controlling the grid-connected point voltage of the household photovoltaic power generation system provided by the embodiment, the embodiment of the invention further provides an embodiment of a device for implementing the method.
Fig. 9 is a schematic structural diagram of a device for controlling a grid-connected point voltage of a photovoltaic power generation system for a user according to an embodiment of the present application. The photovoltaic power generation system is suitable for users in the embodiment of fig. 1, and the execution subject of the embodiment is the photovoltaic inverter in the embodiment of fig. 1. As shown in fig. 9, the device 60 for controlling the grid-connected point voltage of the household photovoltaic power generation system includes a monitoring module 601, a reactive power control module 602, and an active power control module 603;
the monitoring module 601 is used for monitoring the voltage of a grid-connected point after the photovoltaic inverter is in grid-connected operation;
the reactive power control module 602 is configured to, when the voltage of the grid-connected point is greater than a first threshold, enable the photovoltaic inverter to absorb reactive power;
and the active power control module 603 is configured to adjust the active power of the photovoltaic inverter until the grid-connected point voltage meets a preset condition when the reactive power absorbed by the photovoltaic inverter reaches a second threshold and the grid-connected point voltage is greater than a first threshold.
Optionally, the active power control module 603 adjusts the active power of the photovoltaic inverter, including:
determining a first variation function of the active power; wherein the active power decreases at a rate of change less than a third threshold; determining a second change function corresponding to the first change function according to the correlation between the active power and the voltage of the direct current side of the photovoltaic inverter; and regulating the voltage of the direct current side of the photovoltaic inverter according to the second change function.
Optionally, the reactive power control module 602 is further configured to send out reactive power when the voltage of the grid-connected point is less than a fifth threshold until the voltage of the grid-connected point meets a preset condition.
Optionally, the device 60 for controlling the grid-connected point voltage of the household photovoltaic power generation system further includes a grid-connected operation module and a mode adjustment module;
the grid-connected operation module is used for controlling the photovoltaic inverter to be off-grid under the condition that the active power is smaller than a fourth threshold value; and controlling the photovoltaic inverter to operate grid connection again within a first preset time under the condition that the voltage of the grid connection point is reduced to the starting cut-off voltage.
Optionally, the grid-connected operation module determines a start cut-off voltage according to the first threshold and a port voltage of the photovoltaic inverter in the off-grid state, wherein the port voltage is a preset value.
Optionally, the grid-connected operation module controls the photovoltaic inverter to perform grid-connected operation again within a first preset time, and the method includes: determining the optimal grid-connected voltage corresponding to the highest point of the conversion efficiency of the photovoltaic inverter within a preset grid-connected voltage range; adjusting the voltage of the alternating current side of the photovoltaic inverter to the optimal grid-connected voltage; and controlling the photovoltaic inverter to be connected to the grid again within the first preset time.
Optionally, the mode adjusting module is configured to control the operation of the photovoltaic inverter according to at least one of a constant voltage control mode, a constant power factor control mode, or a constant reactive power control mode when the voltage of the grid-connected point meets a preset condition.
The device for controlling the grid-connected point voltage of the household photovoltaic power generation system provided by the embodiment shown in fig. 9 can be used for executing the technical scheme in any one of the above method embodiments, and the implementation principle and the technical effect are similar, and details are not repeated here.
Fig. 10 is a schematic diagram of a grid-connected point voltage control device of a household photovoltaic power generation system according to an embodiment of the present application. As shown in fig. 10, the user of this embodiment uses a grid-connected point voltage control device 70 of a photovoltaic power generation system including: at least one processor 701, a memory 702, and a computer program stored in said memory 702 and executable on said processor 701. The grid-connected point voltage control device of the household photovoltaic power generation system further comprises a communication component 703, wherein the processor 701, the memory 702 and the communication component 703 are connected through a bus 704.
The processor 701, when executing the computer program, implements the steps in the grid-connected point voltage control method embodiment of the photovoltaic power generation system for each user in the above-described method embodiments, such as steps S10 to S30 in the embodiment shown in fig. 2. Alternatively, the processor 701, when executing the computer program, implements the functions of each module/unit in the device embodiment of the user grid-connected point voltage control of the photovoltaic power generation system in the embodiment of fig. 9.
It should be understood that the grid-connected point voltage control device of the household photovoltaic power generation system provided by the embodiment of the application can be a photovoltaic inverter in fig. 1.
The processors 701 may each be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory 702 may be an internal storage unit of the grid-connected point voltage control device of the household photovoltaic power generation system, or an external storage device of the grid-connected point voltage control device of the household photovoltaic power generation system.
Embodiments of the present application further provide a computer-readable storage medium, where a computer program is stored, and when the computer program is executed by a processor, the steps in the foregoing method embodiments may be implemented.
Embodiments of the present application provide a computer program product, which when running on a mobile terminal, enables the mobile terminal to implement the steps in the above method embodiments when executed.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, all or part of the processes in the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium and can implement the steps of the embodiments of the methods described above when the computer program is executed by a processor. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer readable medium may include at least: any entity or device capable of carrying computer program code to a photographing apparatus/terminal apparatus, a recording medium, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), an electrical carrier signal, a telecommunications signal, and a software distribution medium. Such as a usb-disk, a removable hard disk, a magnetic or optical disk, etc. In some jurisdictions, computer-readable media may not be an electrical carrier signal or a telecommunications signal in accordance with legislative and proprietary practices.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus/network device and method may be implemented in other ways. For example, the above-described apparatus/network device embodiments are merely illustrative, and for example, a module or a unit may be divided into only one type of logic function, and may be implemented in other ways, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
Units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
The above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.

Claims (9)

1. A grid-connected point voltage control method of a household photovoltaic power generation system is characterized in that the household photovoltaic power generation system comprises a photovoltaic inverter and a photovoltaic module, wherein the direct current side of the photovoltaic inverter is connected with the photovoltaic module, and the alternating current side of the photovoltaic inverter is connected to a grid; when the amplitude and the frequency of the voltage of the grid-connected point accord with the operation requirement of the photovoltaic inverter and the output voltage of the photovoltaic module is not less than the starting voltage of the photovoltaic inverter, the photovoltaic inverter automatically performs grid-connected operation, and the grid-connected point voltage control method of the user photovoltaic power generation system comprises the following steps:
after the photovoltaic inverter is subjected to grid-connected operation, monitoring the voltage of a grid-connected point by the photovoltaic inverter;
when the voltage of the grid-connected point is larger than a first threshold value, the photovoltaic inverter absorbs reactive power;
under the condition that the reactive power absorbed by the photovoltaic inverter reaches a second threshold value and the voltage of the grid-connected point is greater than the first threshold value, adjusting the active power of the photovoltaic inverter until the voltage of the grid-connected point meets a preset condition;
after the active power of the photovoltaic inverter is adjusted, the grid-connected point voltage control method of the household photovoltaic power generation system further comprises the following steps:
controlling the photovoltaic inverter to be disconnected under the condition that the active power is smaller than a fourth threshold value;
and under the condition that the grid-connected point voltage is reduced to a starting cut-off voltage, controlling the photovoltaic inverter to perform grid-connected operation again within a first preset time.
2. The grid-connected point voltage control method for the household photovoltaic power generation system according to claim 1, wherein the adjusting the active power of the photovoltaic inverter comprises:
determining a first variation function of the active power; wherein the active power decreases at a rate of change that is less than a third threshold;
determining a second change function corresponding to the first change function according to the correlation between the active power and the voltage of the direct current side of the photovoltaic inverter;
and regulating the voltage of the direct current side of the photovoltaic inverter according to the second change function.
3. The method for controlling a grid-connected point voltage of a household photovoltaic power generation system according to claim 2, further comprising:
and determining a starting cut-off voltage according to the first threshold value and the port voltage of the photovoltaic inverter in the off-line state, wherein the port voltage is a preset value.
4. The grid-connected point voltage control method for the household photovoltaic power generation system according to claim 2, wherein the controlling the photovoltaic inverter to perform grid-connected operation again within a first preset time comprises:
determining the optimal grid-connected voltage corresponding to the highest point of the conversion efficiency of the photovoltaic inverter within a preset grid-connected voltage range;
adjusting the voltage of the alternating current side of the photovoltaic inverter to the optimal grid-connected voltage;
and controlling the photovoltaic inverter to be connected to the grid again within the first preset time.
5. The method for controlling a grid-connected point voltage of a household photovoltaic power generation system according to claim 1, wherein after monitoring the grid-connected point voltage, the method for controlling the grid-connected point voltage of the household photovoltaic power generation system further comprises:
and under the condition that the grid-connected point voltage is smaller than a fifth threshold, the photovoltaic inverter sends out reactive power until the grid-connected point voltage meets the preset condition, wherein the fifth threshold is smaller than the first threshold.
6. The method for controlling a grid-connected point voltage of a household photovoltaic power generation system according to claim 1, further comprising:
and under the condition that the voltage of the grid-connected point meets the preset condition, controlling the photovoltaic inverter to operate according to at least one of a constant voltage control mode, a constant power factor control mode or a constant reactive power control mode.
7. A grid-connected point voltage control apparatus of a photovoltaic power generation system for a user, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the grid-connected point voltage control method of the photovoltaic power generation system for the user according to any one of claims 1 to 6 when executing the computer program.
8. A computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the grid-connected point voltage control method for a user of a photovoltaic power generation system according to any one of claims 1 to 6.
9. A household photovoltaic power generation system, comprising: a photovoltaic inverter and a photovoltaic module, wherein the photovoltaic inverter is connected with the photovoltaic module,
the direct current side of the photovoltaic inverter is connected with the photovoltaic module, and the alternating current side of the photovoltaic inverter is used for grid connection; when the amplitude and the frequency of the voltage of the grid-connected point meet the operation requirement of the photovoltaic inverter and the output 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 photovoltaic module is used for converting absorbed solar energy into direct current and sending the direct current to the photovoltaic inverter;
the photovoltaic inverter is used for converting direct current sent by the photovoltaic module into alternating current and executing the steps of the grid-connected point voltage control method of the household photovoltaic power generation system according to any one of claims 1 to 6.
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