Grid-connected point voltage control method and system for improving distributed photovoltaic absorption capability

Abstract

The invention discloses a grid-connected point voltage control method and system for improving distributed photovoltaic absorption capability. The method comprises the steps of obtaining a maximum value and a minimum value of a grid-connected point voltage and a maximum reactive power value of an inverter; based on a target voltage interval set by a power grid dispatching mechanism, a reactive power voltage regulation control strategy of the inverter is set by using the maximum value and the minimum value of the voltage of the grid-connected point and the maximum reactive power value of the inverter; calculating the ratio of the increment of the grid-connected point voltage in the target voltage interval to the active power increment of the inverter; based on the ratio, predicting the maximum value of the active power of the inverter when the voltage of the grid-connected point reaches the maximum value, and taking the maximum value as the upper limit value of the active power of the distributed photovoltaic injection power grid at different installation positions in the power grid; and when the reactive power of the inverter reaches the maximum value and the voltage of the grid-connected point is out of limit, the active power of the inverter is controlled to be not greater than the upper limit value of the active power, so that the problem that the photovoltaic permeability is reduced due to the out-of-limit voltage of the grid-connected point caused by photovoltaic grid connection is solved, and excess photovoltaic power is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of stability and control of new energy power generation systems. Specifically, it relates to a grid connection point voltage control method and system for improving the accommodation capacity of distributed photovoltaic power generation. Background Art

[0002] Currently in China's distribution network, the number of grid-connected distributed photovoltaics is growing rapidly, and the grid-connected capacity is also continuously increasing. The access of photovoltaics has broken the traditional mode of unidirectional power flow in the distribution network, which may lead to reverse power flow and then cause the grid connection point voltage of the photovoltaic power generation system to rise or even exceed the limit. The voltage over-limit problem not only affects the power quality of local loads but also restricts the penetration rate of photovoltaics in the distribution network. Therefore, it is particularly important to study the voltage regulation of the photovoltaic grid connection point.

[0003] Most of the existing technologies rely on traditional reactive power compensation or voltage adjustment methods, such as fixed reactive power compensation, distributed voltage control and other common voltage regulation strategies, including: constant reactive power Q control, constant power factor cosj control, active power output control based on photovoltaic power sources, and Q(U) control based on the grid connection point voltage amplitude. In recent years, many control methods have been correspondingly improved based on these methods. For example, by combining reactive power devices with photovoltaic inverters to increase the standby reactive power capacity of the photovoltaic system, although the problem of inverter reactive power capacity limitation is solved to a certain extent, the cost of the entire system is increased. In addition, an existing dynamic voltage adjustment strategy based on instantaneous voltage can effectively adjust the grid connection point voltage, but it does not consider the change of the maximum power point voltage on the DC side. Most of the existing control methods lack the limitation of the inverter grid connection power factor range and lack consideration of the volatility of photovoltaic output. It is a local optimization, such as only focusing on the improvement of photovoltaic accommodation or only focusing on voltage regulation control, and it is impossible to achieve both. Summary of the Invention

[0004] To solve the deficiencies in the existing technology, the present invention provides a grid connection point voltage control method and system for improving the accommodation capacity of distributed photovoltaics, so as to solve the problem that the grid connection point voltage over-limit caused by photovoltaic grid connection leads to a reduction in the photovoltaic penetration rate and avoid photovoltaic power surplus.

[0005] The present invention adopts the following technical solutions.

[0006] The present invention proposes a grid connection point voltage control method for improving the accommodation capacity of distributed photovoltaics, including:

[0007] Obtain the maximum and minimum values of the grid connection point voltage and the maximum reactive power of the inverter;

[0008] Based on the target voltage range set by the power grid dispatching agency, the reactive power voltage regulation control strategy of the inverter is set by using the maximum and minimum values of the grid connection point voltage and the maximum reactive power of the inverter.

[0009] Calculate the ratio between the increment of the grid connection point voltage and the increment of the active power of the inverter within the target voltage range; based on the ratio, predict the maximum active power of the inverter when the grid connection point voltage reaches the maximum value, and use it as the upper limit of the active power injected into the grid by distributed photovoltaics at different installation positions in the power grid.

[0010] When the reactive power of the inverter reaches the maximum value and the grid connection point voltage exceeds the limit, control the active power of the inverter to be no greater than the upper limit of the active power.

[0011] Preferably, when the grid connection point voltage reaches the maximum value U max , the reactive power of the inverter reaches the maximum value -Q max , where the negative sign indicates that the inverter absorbs reactive power; when the grid connection point voltage reaches the minimum value U min , the reactive power of the inverter reaches the maximum value Q max , indicating that the inverter emits reactive power.

[0012] Preferably, the voltage regulation control strategy of the inverter is set to include:

[0013] When the grid connection point voltage is within the target voltage range, the inverter does not perform voltage regulation, satisfying the following relationship:

[0014] Q = 0, U a ≤ U ≤ U b

[0015] In the formula, Q is the reactive power of the inverter, and U is the grid connection point voltage;

[0016] When the grid connection point voltage is greater than the minimum value and less than the lower bound of the target voltage range, the inverter emits reactive power to increase the grid connection point voltage, satisfying the following relationship:

[0017]

[0018] When the grid connection point voltage is greater than the upper bound of the target voltage range and less than the maximum value, the inverter absorbs reactive power to reduce the grid connection point voltage, satisfying the following relationship:

[0019]

[0020] When the grid connection point voltage is not greater than the minimum value, the inverter emits the maximum reactive power, satisfying the following relationship:

[0021] Q = Q max , U ≤ U min

[0022] When the grid connection point voltage is not less than the maximum value, the inverter absorbs the maximum reactive power, and the following relationship is satisfied:

[0023] Q = -Q max , U ≥ U max

[0024] U a is the lower bound of the target voltage range, and U b is the upper bound of the target voltage range.

[0025] Preferably, according to the relevant technical regulations for the connection of photovoltaic power stations to the grid, the grid dispatching agency sets the target voltage range [U a , U b .

[0026] Preferably, within the target voltage range, the inverter does not emit or absorb reactive power. At this time, the grid connection point voltage and the active power are linearly related. Using U a and the active power P a , U b and the active power P b calculate the ratio between the increment of the grid connection point voltage and the increment of the active power of the inverter within the target voltage range;

[0027] Based on the ratio, predict the maximum active power P max corresponding to the predicted maximum value U max , which is the upper limit of the active power injected into the grid by distributed photovoltaics at different installation positions in the grid.

[0028] The present invention also proposes a grid connection point voltage control system for improving the accommodation capacity of distributed photovoltaics, including:

[0029] A collection module for obtaining the maximum and minimum values of the grid connection point voltage and the maximum reactive power of the inverter;

[0030] A reactive power voltage regulation control module for setting the reactive power voltage regulation control strategy of the inverter based on the target voltage range set by the grid dispatching agency, using the maximum and minimum values of the grid connection point voltage and the maximum reactive power of the inverter;

[0031] An active power voltage regulation control module for calculating the ratio between the increment of the grid connection point voltage and the increment of the active power of the inverter within the target voltage range; based on the ratio, predicting the maximum active power of the inverter when the grid connection point voltage reaches the maximum value, as the upper limit of the active power injected into the grid by distributed photovoltaics at different installation positions in the grid;

[0032] A grid connection point voltage control module for controlling the active power of the inverter not to be greater than the upper limit of the active power when the reactive power of the inverter reaches the maximum value and the grid connection point voltage exceeds the limit.

[0033] Preferably, in the reactive voltage regulation control module, when the grid connection point voltage is within the target voltage range, the inverter does not perform voltage regulation, and the following relationship is satisfied:

[0034] Q = 0, U a ≤ U ≤ U b

[0035] In the formula, Q is the reactive power of the inverter, and U is the grid connection point voltage;

[0036] When the grid connection point voltage is greater than the minimum value and less than the lower bound of the target voltage range, the inverter emits reactive power to increase the grid connection point voltage, and the following relationship is satisfied:

[0037]

[0038] When the grid connection point voltage is greater than the upper bound of the target voltage range and less than the maximum value, the inverter absorbs reactive power to reduce the grid connection point voltage, and the following relationship is satisfied:

[0039]

[0040] When the grid connection point voltage is not greater than the minimum value, the inverter emits the maximum reactive power, and the following relationship is satisfied:

[0041] Q = Q max , U ≤ U min

[0042] When the grid connection point voltage is not less than the maximum value, the inverter absorbs the maximum reactive power, and the following relationship is satisfied:

[0043] Q = -Q max , U ≥ U max

[0044] U a is the lower bound of the target voltage range, and U b is the upper bound of the target voltage range.

[0045] Preferably, in the active voltage regulation control module, within the target voltage range, the inverter does not emit or absorb reactive power. At this time, the grid connection point voltage and the active power are linearly related. Using U a and the active power P a , U b and the active power P b calculate the ratio between the increment of the grid connection point voltage and the increment of the active power of the inverter within the target voltage range;

[0046] Based on the ratio, predict the maximum value U max corresponding to the maximum active power P max , which is the upper limit of the active power injected into the grid by distributed photovoltaics installed at different positions in the power grid.

[0047] The present invention also provides a terminal, comprising a processor and a storage medium; the storage medium is used for storing instructions; the processor is used for operating according to the instructions to execute the steps of the method.

[0048] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps of the method are implemented.

[0049] The beneficial effects of the present invention are as follows. Compared with the prior art, at least the following are included. By controlling the grid connection point voltage of the photovoltaic power generation system in the distribution network, the present invention not only improves the distributed photovoltaic accommodation capacity, but also avoids the over-limit of the grid connection point voltage caused by photovoltaic grid connection and the excess of photovoltaic power. The present invention takes into account the volatility of photovoltaic output, the control structure is simple and easy to implement, and has certain economic benefits. And the present invention proposes a more comprehensive and integrated grid connection point voltage control method. The existing solutions may only... While this patent comprehensively considers factors such as the economic operation of the system, loss minimization, active and reactive power output, etc. during voltage control to achieve better overall benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is a flowchart of the grid connection point voltage control method for improving the distributed photovoltaic accommodation capacity proposed by the present invention;

[0051] Figure 2 is a schematic diagram of the voltage regulation control strategy of the inverter in the embodiment of the present invention;

[0052] Figure 3 is a schematic diagram of the reactive power voltage regulation control strategy in the embodiment of the present invention;

[0053] Figure 4 is a control structure block diagram of the active-reactive power comprehensive control in the embodiment of the present invention;

[0054] Figure 5 is a grid connection point voltage waveform diagram in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0055] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only a part of the embodiments of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0056] The present invention proposes a grid connection point voltage control method for improving the distributed photovoltaic accommodation capacity, which is applicable to a new energy photovoltaic grid connection system. The distributed photovoltaic is connected to the grid through an inverter, such asFigure 1 As shown, the method includes:

[0057] Step 1, obtain the maximum and minimum values of the grid connection point voltage and the maximum reactive power of the inverter;

[0058] Specifically, when the grid connection point voltage reaches the maximum value U max , the reactive power of the inverter reaches the maximum value -Q max , where the negative sign indicates that the inverter absorbs reactive power; when the grid connection point voltage reaches the minimum value U min , the reactive power of the inverter reaches the maximum value Q max , indicating that the inverter emits reactive power.

[0059] Step 2, based on the target voltage range set by the grid dispatching agency, use the maximum and minimum values of the grid connection point voltage and the maximum reactive power of the inverter to set the reactive voltage control strategy of the inverter.

[0060] Specifically, according to the relevant technical regulations of the State Grid Corporation of China for the connection of photovoltaic power plants to the grid, the grid dispatching agency sets the target voltage range [U a , U b , U a is the lower bound of the target voltage range, and U b is the upper bound of the target voltage range;

[0061] As Figure 2 shown, the set voltage regulation control strategy of the inverter includes:

[0062] When the grid connection point voltage is within the target voltage range, the inverter does not perform voltage regulation, satisfying the following relationship:

[0063] Q = 0, U a ≤ U ≤ U b

[0064] where Q is the reactive power of the inverter and U is the grid connection point voltage;

[0065] When the grid connection point voltage is greater than the minimum value and less than the lower bound of the target voltage range, the inverter emits reactive power to increase the grid connection point voltage, satisfying the following relationship:

[0066]

[0067] When the grid connection point voltage is greater than the upper bound of the target voltage range and less than the maximum value, the inverter absorbs reactive power to reduce the grid connection point voltage, satisfying the following relationship:

[0068]

[0069] When the grid connection point voltage is not greater than the minimum value, the inverter emits the maximum reactive power, satisfying the following relationship:

[0070] Q = Q max , U ≤ U min

[0071] When the grid connection point voltage is not less than the maximum value, the inverter absorbs the maximum reactive power, satisfying the following relationship:

[0072] Q = -Q max , U ≥ U max

[0073] The present invention takes the target voltage range set by the power grid dispatching agency as the grid connection point voltage control target, and through setting a reasonable reactive power voltage regulation control strategy, effectively controls the over-limit of the grid connection point voltage, solving the problem of over-limit of the grid connection point voltage caused by photovoltaic grid connection. Moreover, when the active power output by the photovoltaic is less at night, the set reactive power voltage regulation control strategy can also output reactive power to support the grid connection point voltage.

[0074] Step 3: Calculate the ratio between the increment of the grid connection point voltage and the increment of the active power of the inverter within the target voltage range; based on the ratio, predict the maximum active power of the inverter when the grid connection point voltage reaches the maximum value, which is used as the upper limit of the active power injected into the grid by distributed photovoltaics at different installation positions in the power grid.

[0075] As Figure 3 shown, based on the reactive power voltage regulation control strategy set by the present invention, the inverter does not emit or absorb reactive power within the target voltage range. At this time, the grid connection point voltage and the active power are linearly related. Using U a and the active power P a , U b and the active power P b calculate the ratio between the increment of the grid connection point voltage and the increment of the active power of the inverter within the target voltage range. The ratio is the slope of the linear relationship. The determined ratio is not affected by factors such as line impedance and line load. Therefore, the maximum active power P max corresponding to the predicted maximum value U max can be used as the upper limit of the active power injected into the grid by distributed photovoltaics at different installation positions in the power grid, thereby further improving the accommodation capacity of distributed photovoltaics on the basis of avoiding over-limit of the grid connection point voltage.

[0076] In the embodiment, when the grid connection point voltage is within the target range, the photovoltaic power supply operates in this state. At this time, the photovoltaic power supply does not absorb reactive power and only outputs active power, realizing stable control of the grid connection point voltage;

[0077] The present invention suppresses the over-limit of the grid connection point voltage by absorbing reactive power through an inverter, can make full use of the remaining capacity of the inverter, ensure that the active power output by the photovoltaic is injected into the grid, and has good economy;

[0078] Figure 4 The control block diagram of the active-reactive comprehensive control is given. The distributed photovoltaic grid-connected power generation system includes: a photovoltaic array, a Boost circuit, a grid-connected inverter and its corresponding controller. The Boost circuit mainly completes the control of the active power P PV output by the photovoltaic, the control of the working voltage V PV of the photovoltaic array, and usually works in the MPPT state. The inverter is mainly responsible for grid connection control, and the control parameters of its outer loop are the DC bus voltage V dc and the reactive power Q PV output by the photovoltaic. According to the sampled grid connection point voltage U PCC and the active power P PV injected into the grid by the photovoltaic, the active power reference value P ref and the reactive power reference value Q ref required for the voltage regulation strategy are set. After the active reference value is determined, according to the situation of judging voltage over-limit, the working voltage V PV of the photovoltaic array is controlled through the MPPT selection switch (V MPPT is the optional MPPT voltage), and then the PWM reference wave of the Boost circuit is output through the PI regulator to realize the effective control of the active power. After the reactive reference value and the preset DC bus reference value pass through the PI regulator, they are input into the inner loop control of the grid-connected inverter. The advantage of using the PI regulator in each control link is that it can make the steady-state error zero.

[0079] Step 4, when the reactive power of the inverter reaches the maximum value and the grid connection point voltage is over-limit, control the active power of the inverter not to be greater than the active power upper limit value.

[0080] Specifically, when the reactive power absorbed by the inverter is already Q max , if the voltage is still over-limit at this time, limit the active power output of the photovoltaic voltage, limit the active power output of the photovoltaic to ensure that the grid connection voltage is not over-limit. The voltage over-limit problem not only affects the power quality of local loads, but also limits the penetration rate of photovoltaic in the distribution network. Solving the voltage over-limit problem can avoid unnecessary reactive power flow and improve the consumption capacity of photovoltaic.

[0081] Specifically, in step 4, when the photovoltaic power generation system enters the emergency voltage regulation state, limit the output of the photovoltaic active power. After voltage regulation, the grid connection point voltage drops to a reasonable voltage range;

[0082] Run the MATLAB / SIMULINK simulation software to conduct simulation verification on the active-reactive power integrated voltage regulation proposed in the present invention. Set the light intensity to increase from 1000 W / m 2 to 1400 W / m 2 . The waveform of the grid-connected point voltage is as shown in Figure 5 . Before the simulation reaches 3 s, the photovoltaic power generation system has been operating in the first state, that is, the state of purely outputting active power; when the simulation reaches 3 s, the light intensity increases to 1400 W / m 2 . At this time, the active power output by the photovoltaic increases, and the grid-connected point voltage increases accordingly, but it has not reached the situation where the active power output needs to be limited. Therefore, the photovoltaic power generation system is operating in the second state, that is, the reactive power voltage regulation state; until the simulation reaches 5.8 s, the voltage at the grid-connected point exceeds the limit, exceeding the power supply voltage deviation allowed by the national standard. At this time, the photovoltaic power generation system needs to enter the emergency voltage regulation state to limit the output of the photovoltaic active power. After voltage regulation, the grid-connected point voltage drops to a reasonable voltage range, proving that this strategy is effective.

[0083] The simulation example verifies the effectiveness of this method and has certain economic benefits.

[0084] The present invention also proposes a grid-connected point voltage control system for improving the accommodation capacity of distributed photovoltaics, including:

[0085] A collection module for obtaining the maximum and minimum values of the grid-connected point voltage and the maximum reactive power of the inverter;

[0086] A reactive power voltage regulation control module for setting the reactive power voltage regulation control strategy of the inverter based on the target voltage range set by the grid dispatching agency, using the maximum and minimum values of the grid-connected point voltage and the maximum reactive power of the inverter;

[0087] An active power voltage regulation control module for calculating the ratio between the increment of the grid-connected point voltage and the increment of the active power of the inverter within the target voltage range; based on the ratio, predicting the maximum active power of the inverter when the grid-connected point voltage reaches the maximum value, and using it as the upper limit of the active power injected into the grid by distributed photovoltaics at different installation positions in the grid;

[0088] A grid-connected point voltage control module for controlling the active power of the inverter not to be greater than the upper limit of the active power when the reactive power of the inverter reaches the maximum value and the grid-connected point voltage exceeds the limit.

[0089] Preferably, in the reactive power voltage regulation control module, when the grid-connected point voltage is within the target voltage range, the inverter does not perform voltage regulation, satisfying the following relationship:

[0090] Q = 0, U a ≤U≤U b

[0091] Wherein, Q is the reactive power of the inverter, and U is the grid connection point voltage;

[0092] When the grid connection point voltage is greater than the minimum value and less than the lower bound of the target voltage range, the inverter emits reactive power to increase the grid connection point voltage, satisfying the following relational expression:

[0093]

[0094] When the grid connection point voltage is greater than the upper bound of the target voltage range and less than the maximum value, the inverter absorbs reactive power to lower the grid connection point voltage, satisfying the following relational expression:

[0095]

[0096] When the grid connection point voltage is not greater than the minimum value, the inverter emits the maximum reactive power, satisfying the following relational expression:

[0097] Q = Q max , U ≤ U min

[0098] When the grid connection point voltage is not less than the maximum value, the inverter absorbs the maximum reactive power, satisfying the following relational expression:

[0099] Q = -Q max , U ≥ U max

[0100] U a is the lower bound of the target voltage range, and U b is the upper bound of the target voltage range.

[0101] Preferably, in the active voltage regulation control module, within the target voltage range, the inverter does not emit or absorb reactive power. At this time, the grid connection point voltage and the active power are linearly related. Using U a and the active power P a , U b and the active power P b calculate the ratio between the increment of the grid connection point voltage and the increment of the active power of the inverter within the target voltage range;

[0102] Based on the ratio, predict the maximum value U max corresponding to the maximum active power P max , which is the upper limit value of the active power injected into the grid by distributed photovoltaics installed at different positions in the power grid.

[0103] The present disclosure may be a system, a method, and / or a computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions thereon for causing a processor to implement various aspects of the present disclosure.

[0104] A computer-readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. A computer-readable storage medium may be, for example—but not limited to—an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disc (DVD), a memory stick, a floppy disk, a mechanically encoded device such as a punched card or raised structures in grooves having instructions stored thereon, and any suitable combination of the foregoing. The computer-readable storage medium as used herein is not construed as being a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., an optical pulse through an optical fiber cable), or an electrical signal transmitted through a wire.

[0105] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to respective computing / processing devices, or can be downloaded to an external computer or an external storage device through a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network may include a copper transmission cable, an optical fiber transmission, a wireless transmission, a router, a firewall, a switch, a gateway computer, and / or an edge server. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in a computer-readable storage medium in each computing / processing device.

[0106] Computer program instructions for performing the operations of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state-setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages such as Smalltalk, C++, etc., and conventional procedural programming languages such as the "C" language or similar programming languages. The computer-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, executed as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., through the Internet using an Internet service provider). In some embodiments, by using the state information of the computer-readable program instructions to customize an electronic circuit, such as a programmable logic circuit, a field-programmable gate array (FPGA), or a programmable logic array (PLA), the electronic circuit can execute the computer-readable program instructions to implement various aspects of the present disclosure.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific embodiments of the present invention, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A grid connection point voltage control method for improving the absorption capacity of distributed photovoltaic power generation, characterized in that: include: Obtain the maximum and minimum values ​​of the grid-connected point voltage and the maximum reactive power of the inverter; Based on the target voltage range set by the grid dispatching organization, the reactive voltage regulation control strategy of the inverter is set by using the maximum and minimum values ​​of the grid connection point voltage and the maximum reactive power of the inverter; Calculate the ratio between the grid connection point voltage increment and the inverter active power increment within the target voltage range; based on the ratio, predict the maximum active power of the inverter when the grid connection point voltage reaches the maximum value, which serves as the upper limit of the active power injected into the grid by distributed photovoltaics at different installation locations in the grid; When the reactive power of the inverter reaches the maximum value and the grid connection point voltage exceeds the limit, the active power of the inverter is controlled not to be greater than the upper limit of the active power.

2. The grid connection point voltage control method for improving the distributed photovoltaic absorption capacity according to claim 1 is characterized in that: The grid voltage reaches the maximum value U max When the inverter's reactive power reaches its maximum value -Q max , where the negative sign indicates that the inverter absorbs reactive power; the grid-connected point voltage reaches the minimum value U min When the inverter's reactive power reaches its maximum value, Q max , indicating that the inverter generates reactive power.

3. The grid connection point voltage control method for improving the distributed photovoltaic absorption capacity according to claim 2 is characterized in that: The voltage regulation control strategy of the inverter is set, including: When the grid-connected point voltage is within the target voltage range, the inverter does not adjust the voltage, and the following relationship is satisfied: Q=0,U a ≤U≤U b In the formula, Q is the reactive power of the inverter, and U is the grid connection point voltage; When the grid-connected point voltage is greater than the minimum value and less than the lower limit of the target voltage range, the inverter generates reactive power to increase the grid-connected point voltage, satisfying the following relationship: When the grid-connected point voltage is greater than the upper limit of the target voltage interval and less than the maximum value, the inverter absorbs reactive power to reduce the grid-connected point voltage, satisfying the following relationship: When the grid-connected point voltage is not greater than the minimum value, the inverter outputs the maximum reactive power, satisfying the following relationship: Q=Q max ,U≤U min When the grid-connected point voltage is not less than the maximum value, the inverter absorbs the maximum reactive power and satisfies the following relationship: Q=-Q max ,U≥U max U a is the lower limit of the target voltage range, U b is the upper limit of the target voltage range.

4. The grid connection point voltage control method for improving the distributed photovoltaic absorption capacity according to claim 3 is characterized in that: According to the relevant technical regulations for the connection of photovoltaic power plants to the power grid, the grid dispatching agency sets the target voltage range [U a ,U b ].

5. The grid connection point voltage control method for improving the distributed photovoltaic absorption capacity according to claim 1 is characterized in that: In the target voltage range, the inverter does not emit or absorb reactive power. At this time, the grid voltage and active power are linearly related. a And active power P a , U b And active power P b Calculate the ratio between the grid connection point voltage increment and the inverter active power increment within the target voltage range; Based on the ratio, the predicted maximum value U max The corresponding maximum active power P max , the upper limit of active power injected into the grid by distributed photovoltaics at different installation locations in the grid.

6. A grid-connected point voltage control system for improving the absorption capacity of distributed photovoltaic power generation, characterized in that: include: The acquisition module is used to obtain the maximum and minimum values ​​of the grid-connected point voltage and the maximum reactive power of the inverter; The reactive voltage regulation control module is used to set the reactive voltage regulation control strategy of the inverter based on the target voltage range set by the grid dispatching organization, using the maximum and minimum values ​​of the grid connection point voltage and the maximum reactive power of the inverter; The active voltage regulation control module is used to calculate the ratio between the grid connection point voltage increment and the inverter active power increment within the target voltage range; based on the ratio, the maximum active power of the inverter is predicted when the grid connection point voltage reaches the maximum value, which is used as the upper limit of the active power injected into the grid by distributed photovoltaics at different installation locations in the grid; The grid connection point voltage control module is used to control the active power of the inverter not to be greater than the upper limit of the active power when the reactive power of the inverter reaches the maximum value and the grid connection point voltage exceeds the limit.

7. The grid connection point voltage control system for improving the distributed photovoltaic absorption capacity according to claim 6 is characterized in that: In the reactive voltage regulation control module, when the grid-connected point voltage is within the target voltage range, the inverter does not regulate the voltage, satisfying the following relationship: Q=0,U a ≤U≤U b In the formula, Q is the reactive power of the inverter, and U is the grid connection point voltage; When the grid-connected point voltage is greater than the minimum value and less than the lower limit of the target voltage range, the inverter generates reactive power to increase the grid-connected point voltage, satisfying the following relationship: When the grid-connected point voltage is greater than the upper limit of the target voltage interval and less than the maximum value, the inverter absorbs reactive power to reduce the grid-connected point voltage, satisfying the following relationship: When the grid-connected point voltage is not greater than the minimum value, the inverter outputs the maximum reactive power, satisfying the following relationship: Q=Q max ,U≤U min When the grid-connected point voltage is not less than the maximum value, the inverter absorbs the maximum reactive power and satisfies the following relationship: Q=-Q max ,U≥U max U a is the lower limit of the target voltage range, U b is the upper limit of the target voltage range.

8. The grid connection point voltage control system for improving the distributed photovoltaic absorption capacity according to claim 7 is characterized in that: In the active voltage regulation control module, the inverter does not emit or absorb reactive power within the target voltage range. At this time, the grid voltage and active power are linearly related. a And active power P a , U b And active power P b Calculate the ratio between the grid connection point voltage increment and the inverter active power increment within the target voltage range; Based on the ratio, the predicted maximum value U max The corresponding maximum active power P max , the upper limit of active power injected into the grid by distributed photovoltaics at different installation locations in the grid.

9. A terminal comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 5.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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