A distributed photovoltaic area voltage control method, device, equipment and product

Abstract

The present invention discloses a distributed photovoltaic substation voltage control method, device, electronic equipment and product. The present invention relies on the energy storage device and photovoltaic inverter in the substation energy storage system in the distribution network to quickly adjust the voltage of the photovoltaic grid-connected point. When it is determined that the grid-connected voltage of the photovoltaic grid-connected point exceeds the limit, the active power is first absorbed or released by charging or discharging the energy storage device in the substation, thereby achieving the purpose of grid-connected voltage control. Then, when the adjusted grid-connected voltage still exceeds the limit, the reactive power of the photovoltaic inverter in the substation is adjusted again to adjust the grid-connected voltage to within the calibrated grid-connected voltage range to ensure stable access of the distributed photovoltaic power generation system. Therefore, the present invention can solve the problem that the access of the distributed photovoltaic power generation system to the distribution network will cause abnormal voltage deviation, thereby leading to voltage exceeding the limit. Therefore, it is very suitable for large-scale application and promotion.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic area voltage regulation, and specifically relates to a distributed photovoltaic area voltage regulation method, device, equipment and product. Background Art

[0002] As countries become increasingly concerned about environmental protection and energy shortages, resolving the contradiction between energy and the environment has become an unavoidable issue in the process of energy development in various countries. Among them, photovoltaic power generation, as a green energy, has been widely used in recent years and has become one of the fastest-growing renewable energy sources. In actual application, distributed photovoltaic power generation systems use solar power generation to reduce environmental pollution and thus achieve clean energy conversion. Therefore, distributed photovoltaic power generation has become a key component of the distribution network.

[0003] However, while photovoltaic power generation brings many advantages, it also brings certain problems to the smart distribution network. Among them, photovoltaic power generation is intermittent and random. Therefore, its access to the grid will cause abnormal voltage deviations, which can easily lead to grid stability problems such as voltage fluctuations or even voltage over-limit. Voltage over-limit not only affects the power quality of local loads, but also limits the penetration rate of photovoltaics in the distribution network. Therefore, how to provide a photovoltaic substation voltage control method that can meet the requirements of rapid voltage regulation of photovoltaic grid connection points has become an urgent problem to be solved. Summary of the Invention

[0004] The purpose of the present invention is to provide a distributed photovoltaic area voltage control method, device, equipment and product to solve the problem in the prior art that the distributed photovoltaic power generation system will cause voltage exceeding the limit when connected to the distribution network, thereby affecting the stability of the power grid and limiting the penetration rate of photovoltaic in the distribution network.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, a distributed photovoltaic area voltage control method is provided, which is applied to the area energy storage system corresponding to each photovoltaic grid connection point in the distribution network, wherein the method includes:

[0007] Obtain grid-connected power parameters of any photovoltaic grid-connected point in the distribution network;

[0008] Determining whether the grid-connected voltage of any photovoltaic grid-connected point exceeds a limit based on the grid-connected power parameters;

[0009] If so, controlling the energy storage device in the energy storage system of the corresponding area of ​​any photovoltaic grid-connected point to charge or discharge, so as to adjust the grid-connected voltage by charging or discharging the energy storage device to obtain an adjusted grid-connected voltage;

[0010] Determining whether the adjusted grid-connected voltage exceeds a limit;

[0011] If so, the reactive power of the photovoltaic inverter in the energy storage system of the area corresponding to any photovoltaic grid-connected point is adjusted according to the adjusted grid-connected voltage, so as to adjust the adjusted grid-connected voltage to within the calibrated grid-connected voltage range by adjusting the reactive power of the photovoltaic inverter, so as to complete the regulation of the distributed photovoltaic area voltage after adjustment.

[0012] Based on the above-disclosed content, the present invention utilizes the substation energy storage system in the distribution network to regulate the voltage of the photovoltaic grid-connected point in the distribution network. The present invention first obtains the grid-connected power parameters of any photovoltaic grid-connected point in the distribution network, and then determines whether the grid-connected voltage of any photovoltaic grid-connected point exceeds the limit based on the grid-connected power parameters. If so, the energy storage device in the substation energy storage system corresponding to the any photovoltaic grid-connected point is controlled to charge or discharge, so as to absorb the excess active power of the photovoltaic system by charging the energy storage device, thereby reducing the grid-connected voltage, or release the active power by discharging the energy storage device, thereby increasing the voltage. In this way, the grid-connected voltage can be regulated by charging and discharging the energy storage device in the substation in the distribution network. Then, it is further determined whether the adjusted grid-connected voltage is still over the limit. If so, the grid-connected voltage is adjusted again by adjusting the reactive power of the photovoltaic inverter in the substation, so as to adjust it to within the calibrated grid-connected voltage range, thereby ensuring that the voltage of the photovoltaic grid-connected point does not exceed the limit, thereby achieving the purpose of distributed photovoltaic substation voltage regulation.

[0013] Through the above design, the present invention relies on the energy storage equipment and photovoltaic inverter in the substation energy storage system in the distribution network to quickly adjust the voltage of the photovoltaic grid-connected point; wherein, when it is determined that the grid-connected voltage of the photovoltaic grid-connected point exceeds the limit, the active power is first absorbed or released by charging or discharging the energy storage equipment in the substation, thereby achieving the purpose of grid-connected voltage regulation; then, when the adjusted grid-connected voltage still exceeds the limit, the grid-connected voltage is adjusted again by adjusting the reactive power of the photovoltaic inverter in the substation, so as to adjust it to within the calibrated grid-connected voltage range to ensure the stable access of the distributed photovoltaic power generation system; thus, the present invention can solve the problem that the voltage deviation abnormality caused by the access of the distributed photovoltaic power generation system to the distribution network leads to the voltage exceeding the limit, thereby improving the power quality of the local load and the penetration rate of photovoltaic in the distribution network; therefore, it is very suitable for large-scale application and promotion.

[0014] In one possible design, the grid-connected power parameters include: photovoltaic active power and photovoltaic reactive power of any photovoltaic grid-connected point, and load active power and load reactive power of any photovoltaic grid-connected point;

[0015] Wherein, judging whether the grid-connected voltage of any photovoltaic grid-connected point exceeds a limit according to the grid-connected power parameter includes:

[0016] Obtaining the distribution network bus voltage, distribution network bus resistance, and distribution network bus impedance corresponding to any photovoltaic grid-connected point;

[0017] Calculating a grid-connected power lower limit based on the distribution network bus voltage, the distribution network bus resistance, the distribution network bus impedance, the voltage lower limit within the calibrated grid-connected voltage range, the photovoltaic reactive power, and the load reactive power; and calculating a grid-connected power upper limit based on the distribution network bus voltage, the distribution network bus resistance, the distribution network bus impedance, the voltage upper limit within the calibrated grid-connected voltage range, the photovoltaic reactive power, and the load reactive power;

[0018] Determining a difference between the photovoltaic active power and the load active power;

[0019] Determining whether the difference is between the grid-connected power lower limit and the grid-connected power upper limit;

[0020] If not, it is determined that the grid-connected voltage of any photovoltaic grid-connected point exceeds the limit.

[0021] In one possible design, calculating the grid-connected power lower limit based on the distribution network bus voltage, the distribution network bus resistance, the distribution network bus impedance, the voltage lower limit within the calibrated grid-connected voltage range, the photovoltaic reactive power, and the load reactive power includes:

[0022] According to the following formula (1), the grid-connected power lower limit is calculated;

[0023]

[0024] In the above formula (1), P min Indicates the lower limit of the grid-connected power, Indicates the lower limit of voltage within the calibrated grid voltage range, U s represents the distribution network bus voltage, Q pcc represents the photovoltaic reactive power, Q L represents the load reactive power, X represents the distribution network bus impedance value, and R represents the distribution network bus resistance value.

[0025] In one possible design, controlling the energy storage device in the energy storage system of the corresponding substation at any photovoltaic grid-connected point to charge or discharge includes:

[0026] Obtaining the state of charge of the energy storage device, and determining whether the energy storage device has charge and discharge capabilities based on the state of charge;

[0027] If so, the over-limit status of the grid-connected voltage of any photovoltaic grid-connected point is obtained, and the energy storage device is controlled to charge or discharge according to the over-limit status; otherwise, the reactive power of the photovoltaic inverter in the energy storage system of the substation corresponding to any photovoltaic grid-connected point is adjusted according to the grid-connected voltage, so as to adjust the grid-connected voltage to within the calibrated grid-connected voltage range by adjusting the reactive power of the photovoltaic inverter;

[0028] Among them, the over-limit state is lower than the voltage lower limit value within the calibrated grid-connected voltage range or higher than the voltage upper limit value within the calibrated grid-connected voltage range, and if the over-limit state is lower than the voltage lower limit value, the energy storage device is controlled to discharge to increase the grid-connected voltage; if the over-limit state is higher than the voltage upper limit value, the energy storage device is controlled to charge to reduce the grid-connected voltage.

[0029] In one possible design, determining whether the adjusted grid-connected voltage exceeds a limit includes:

[0030] Determining whether the adjusted grid-connected voltage is within the calibrated grid-connected voltage range;

[0031] If not, it is determined that the adjusted grid-connected voltage exceeds the limit;

[0032] Accordingly, adjusting the reactive power of the photovoltaic inverter in the energy storage system in the area corresponding to any photovoltaic grid-connected point according to the adjusted grid-connected voltage includes:

[0033] Obtaining a maximum grid-connected voltage and a minimum grid-connected voltage, wherein the calibrated grid-connected voltage range is between the maximum grid-connected voltage and the minimum grid-connected voltage;

[0034] constructing a reactive power regulation function according to the maximum grid voltage, the minimum grid voltage, the calibrated grid voltage range, and the adjusted grid voltage;

[0035] The reactive power of the photovoltaic inverter is adjusted according to the reactive power adjustment function.

[0036] In one possible design, a reactive power regulation function is constructed based on the maximum grid voltage, the minimum grid voltage, the calibrated grid voltage range, and the adjusted grid voltage, including:

[0037] According to the following formula (2), the reactive power regulation function is constructed;

[0038]

[0039] In the above formula (2), Qn represents the reactive power regulation function, Indicates the maximum reactive output capacity of the photovoltaic inverter, U′ pcc represents the adjusted grid-connected voltage, Indicates the minimum value of the grid-connected voltage, Indicates the maximum value of the grid-connected voltage, and Indicates the voltage upper limit and voltage lower limit of the calibration grid voltage range, wherein, when Q n When it is positive, it means that the photovoltaic inverter outputs reactive power. n When it is negative, it means that the PV inverter absorbs reactive power.

[0040] In one possible design, after adjusting the reactive power of the photovoltaic inverter in the energy storage system in the substation corresponding to any photovoltaic grid-connected point, the method further includes:

[0041] Obtaining the latest grid-connected voltage of any photovoltaic grid-connected point;

[0042] Determining whether the latest grid-connected voltage exceeds a limit;

[0043] If so, adjusting the photovoltaic active power of any photovoltaic grid-connected point to the active power upper limit, and after adjusting the photovoltaic active power to the active power upper limit, obtaining the output active power of the photovoltaic inverter;

[0044] According to the output active power and in accordance with the following formula (3), the maximum reactive output capacity of the photovoltaic inverter is updated to obtain an updated maximum reactive output capacity;

[0045]

[0046] In the above formula (3), Represents the updated maximum reactive output capacity, P s represents the output active power, δ represents the power control factor;

[0047] The reactive power of the photovoltaic inverter is adjusted according to the updated maximum reactive output capacity and the latest grid-connected voltage, so as to adjust the latest grid-connected voltage to within the calibrated grid-connected voltage range by adjusting the reactive power of the photovoltaic inverter.

[0048] In a second aspect, a distributed photovoltaic area voltage control device is provided, which is applied to the area energy storage system corresponding to each photovoltaic grid connection point in the distribution network, wherein the device includes:

[0049] An acquisition unit, used to obtain grid-connected power parameters of any photovoltaic grid-connected point in the distribution network;

[0050] a judgment unit, configured to judge whether the grid-connected voltage of any photovoltaic grid-connected point exceeds a limit according to the grid-connected power parameter;

[0051] a charge and discharge control unit, configured to control the energy storage device in the energy storage system of the corresponding substation of any photovoltaic grid-connected point to charge or discharge when the judgment unit determines that the grid-connected voltage exceeds the limit, so as to adjust the grid-connected voltage by charging or discharging the energy storage device to obtain an adjusted grid-connected voltage;

[0052] The judging unit is further configured to judge whether the adjusted grid-connected voltage exceeds a limit;

[0053] The inverter control unit is used to adjust the reactive power of the photovoltaic inverter in the energy storage system of the substation corresponding to any photovoltaic grid-connected point according to the adjusted grid-connected voltage when the judgment unit determines that the adjusted grid-connected voltage exceeds the limit, so as to adjust the adjusted grid-connected voltage to within the calibrated grid-connected voltage range by adjusting the reactive power of the photovoltaic inverter, so as to complete the regulation of the distributed photovoltaic substation voltage after adjustment.

[0054] In the third aspect, another distributed photovoltaic area voltage control device is provided. Taking the device as an electronic device as an example, it includes a memory, a processor and a transceiver that are communicatively connected in sequence, wherein the memory is used to store computer programs, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute the distributed photovoltaic area voltage control method as described in the first aspect or any possible design of the first aspect.

[0055] In a fourth aspect, a storage medium is provided, on which instructions are stored. When the instructions are run on a computer, the distributed photovoltaic area voltage control method as described in the first aspect or any possible design of the first aspect is executed.

[0056] In a fifth aspect, a computer program product comprising instructions is provided, which, when executed on a computer, causes the computer to execute the distributed photovoltaic area voltage control method as described in the first aspect or any possible design of the first aspect.

[0057] Beneficial effects:

[0058] (1) The present invention relies on the energy storage equipment and photovoltaic inverter in the substation energy storage system in the distribution network to quickly adjust the voltage of the photovoltaic grid-connected point; wherein, when it is determined that the grid-connected voltage of the photovoltaic grid-connected point exceeds the limit, the active power is first absorbed or released by charging or discharging the energy storage equipment in the substation, thereby achieving the purpose of grid-connected voltage regulation; then, when the adjusted grid-connected voltage still exceeds the limit, the grid-connected voltage is adjusted again by adjusting the reactive power of the photovoltaic inverter in the substation, thereby adjusting it to within the calibrated grid-connected voltage range to ensure the stable access of the distributed photovoltaic power generation system; thus, the present invention can solve the problem that the voltage deviation is abnormal when the distributed photovoltaic power generation system is connected to the distribution network, thereby causing the voltage to exceed the limit, thereby improving the power quality of the local load and the penetration rate of photovoltaic in the distribution network; therefore, it is very suitable for large-scale application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 A schematic diagram of the steps of the distributed photovoltaic area voltage control method provided by an embodiment of the present invention;

[0060] Figure 2 A schematic diagram of the structure of a distributed photovoltaic area voltage control device provided by an embodiment of the present invention;

[0061] Figure 3 A schematic structural diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0062] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be briefly introduced below in conjunction with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structure of the drawings is only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0063] It should be understood that although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element can be referred to as a second element, and similarly, a second element can be referred to as a first element without departing from the scope of the exemplary embodiments of the present invention.

[0064] It should be understood that the term "and / or" that may appear in this document is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B may indicate three situations: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" that may appear in this document describes another type of association object relationship, indicating that two relationships may exist. For example, A / and B may indicate two situations: A exists alone, and A and B exist alone. In addition, the character " / " that may appear in this document generally indicates that the previous and subsequent associated objects are in an "or" relationship.

[0065] Example:

[0066] See also Figure 1 As shown, the distributed photovoltaic substation voltage control method provided in this embodiment is applied to the substation energy storage system corresponding to each photovoltaic grid-connected point in the distribution network, that is, the photovoltaic grid-connected point voltage is initially adjusted by charging and discharging the energy storage device in the substation energy storage system in the distribution network, and then combined with the photovoltaic inverter in the distribution network to realize the secondary adjustment of the photovoltaic grid-connected point voltage, thereby adjusting it to within the calibrated grid-connected voltage range to ensure the stable access of the distributed photovoltaic power generation system; thus, the method can solve the problem that the voltage deviation is abnormal when the distributed photovoltaic power generation system is connected to the distribution network, thereby causing the voltage to exceed the limit, thereby improving the power quality of the local load and the penetration rate of photovoltaics in the distribution network; therefore, it is very suitable for large-scale application and promotion; among them, for example, the method can be but not limited to running on the control end side of the substation energy storage system. It can be understood that the aforementioned execution subject does not constitute a limitation on the embodiment of the present application. Accordingly, the operation steps of the method can be but not limited to the following steps S1 to S5.

[0067] S1. Obtain the grid-connected power parameters of any photovoltaic grid-connected point in the distribution network; in specific applications, the aforementioned grid-connected power parameters may include, but are not limited to: the photovoltaic active power and photovoltaic reactive power of any photovoltaic grid-connected point, and the load active power and load reactive power of any photovoltaic grid-connected point; thus, after obtaining the aforementioned parameters, it may be based on this to determine whether the grid-connected voltage of any photovoltaic grid-connected point exceeds the limit, wherein the over-limit judgment process may be, but is not limited to, as shown in the following step S2.

[0068] S2. Based on the grid-connected power parameters, determine whether the grid-connected voltage of any of the photovoltaic grid-connected points exceeds the limit; in this embodiment, the grid-connected power upper limit and the grid-connected power lower limit are first calculated, and then, based on the photovoltaic active power and the load active power of any of the aforementioned photovoltaic grid-connected points, as well as the aforementioned grid-connected power upper limit and lower limit, determine whether the aforementioned grid-connected voltage exceeds the limit; wherein, the specific judgment process can be but is not limited to the following steps S21 to S25.

[0069] S21. Obtain the distribution network bus voltage, distribution network bus resistance and distribution network bus impedance corresponding to any of the photovoltaic grid-connected points; in this embodiment, the distribution network bus resistance and distribution network bus impedance can be measured in advance and then pre-stored in the control terminal; in this way, after obtaining the above-mentioned data, the grid-connected power parameters of any of the photovoltaic grid-connected points can be combined to calculate the upper and lower limits of the grid-connected power, and then based on the upper and lower limits of the grid-connected power, the grid voltage over-limit judgment can be performed; wherein, the calculation process of the upper and lower limits of the grid-connected power can be but is not limited to the following step S22.

[0070] S22. Calculate the lower limit of the grid-connected power based on the distribution network bus voltage, the distribution network bus resistance, the distribution network bus impedance, the lower limit of the voltage within the calibrated grid-connected voltage range, the photovoltaic reactive power, and the load reactive power; and calculate the upper limit of the grid-connected power based on the distribution network bus voltage, the distribution network bus resistance, the distribution network bus impedance, the upper limit of the voltage within the calibrated grid-connected voltage range, the photovoltaic reactive power, and the load reactive power; in this embodiment, the calculation principles of the upper and lower limits of the grid-connected power are the same, and the following explanation is made by taking the lower limit of the grid-connected power as an example.

[0071] Optionally, the grid-connected power lower limit value may be calculated according to, but not limited to, the following formula (1).

[0072]

[0073] In the above formula (1), P min Indicates the lower limit of the grid-connected power, Indicates the lower limit of voltage within the calibrated grid voltage range, U s represents the distribution network bus voltage, Q pcc represents the photovoltaic reactive power, Q L represents the load reactive power, X represents the distribution network bus impedance value, and R represents the distribution network bus resistance value.

[0074] In this embodiment, the fundamental reason for the voltage exceeding the limit at the photovoltaic grid-connected point is the change in the photovoltaic system power. Therefore, the power can be used as the basis for over-limit judgment. In this way, this embodiment calculates the upper and lower limits of the aforementioned grid-connected power to make an over-limit judgment on the grid-connected voltage. At the same time, when calculating the lower limit of the grid-connected power, the lower limit of the voltage in formula (1) is replaced by the upper limit of the voltage within the calibrated grid-connected voltage range.

[0075] In this way, based on the above formula (1), after calculating the upper and lower limits of the grid-connected power, the difference between the photovoltaic active power and the load active power can be used as the power value corresponding to the grid-connected voltage of any photovoltaic grid-connected point. The judgment process can be, but is not limited to, as shown in the following steps S23 to S25.

[0076] S23. Determine the difference between the photovoltaic active power and the load active power. In this embodiment, after calculating the difference between the photovoltaic active power and the load active power, it can be determined whether it is between the upper and lower limits of the aforementioned grid-connected power. If it is, it means that the grid-connected voltage is within the limit; otherwise, it means that it is beyond the limit. The process is shown in the following steps S24 and S25.

[0077] S24. Determine whether the difference is between the grid-connected power lower limit and the grid-connected power upper limit.

[0078] S25. If not, determine that the grid-connected voltage of any of the photovoltaic grid-connected points exceeds the limit.

[0079] In this embodiment, if the difference in the aforementioned step S23 is between the grid-connected power lower limit and the grid-connected power upper limit, it means that the grid-connected voltage is within the aforementioned calibrated grid-connected voltage range and no voltage adjustment is required; conversely, as long as it is less than the grid-connected power lower limit or greater than the grid-connected power upper limit, it means that the grid-connected voltage is not within the allowable grid-connected voltage range (i.e., the calibrated grid-connected voltage range); at this time, it is determined that the grid voltage exceeds the limit and voltage adjustment is required.

[0080] Thus, through the aforementioned steps S21 to S25, after determining that the grid-connected voltage of any photovoltaic grid-connected point exceeds the limit based on the grid-connected voltage parameters, the grid-connected voltage can be adjusted; wherein, this embodiment utilizes the charging and discharging of the energy storage device in the energy storage system of the substation corresponding to any photovoltaic grid-connected point to adjust the grid-connected voltage, and the process can be, but is not limited to, as shown in the following step S3.

[0081] S3. If so, control the energy storage device in the substation energy storage system corresponding to any of the photovoltaic grid-connected points to charge or discharge, so as to adjust the grid-connected voltage by charging or discharging the energy storage device to obtain the adjusted grid-connected voltage; in this embodiment, substation energy storage refers to an energy storage system installed in the distribution substation for dynamic capacity expansion, load fluctuation suppression and smoothing the output of new energy power generation in the substation, which can turn the entire substation into a stable load or power source, thereby improving the power quality and grid security; that is, in actual use, in order to ensure the stable access of the distributed photovoltaic power generation system to the distribution network, the existing distribution network is mostly equipped with the substation storage system. Therefore, this embodiment can use the energy storage device in the substation energy storage system to adjust the grid-connected voltage.

[0082] In this embodiment, the steps for adjusting the grid-connected voltage are as follows:

[0083] S31. Obtain the state of charge of the energy storage device, and determine whether the energy storage device has charge and discharge capabilities based on the state of charge; in specific applications, the state of charge refers to the amount of electricity in the energy storage device, wherein when the amount of electricity is within a preset range, it is determined that it has charge and discharge capabilities; optionally, taking into account overcharge and over-discharge, for example, when the amount of electricity is within the range of [30,70], it is determined that the energy storage device has charge and discharge capabilities.

[0084] After determining that the energy storage device has the charging and discharging capability, the charging and discharging of the energy storage device can be used to adjust the grid voltage, and the process can be but is not limited to the following step S32.

[0085] S32. If so, obtain the over-limit status of the grid-connected voltage of any photovoltaic grid-connected point, and control the energy storage device to charge or discharge according to the over-limit status; otherwise, adjust the reactive power of the photovoltaic inverter in the energy storage system of the substation corresponding to any photovoltaic grid-connected point according to the grid-connected voltage, so as to adjust the grid-connected voltage to within the calibrated grid-connected voltage range by adjusting the reactive power of the photovoltaic inverter.

[0086] In this embodiment, when the energy storage device does not have the charging and discharging capabilities, the grid-connected voltage is adjusted with the help of a photovoltaic inverter. The specific process of voltage adjustment with the help of a photovoltaic inverter is described in detail below.

[0087] At the same time, for example, the over-limit state is lower than the voltage lower limit value within the calibrated grid-connected voltage range or higher than the voltage upper limit value within the calibrated grid-connected voltage range. If the over-limit state is lower than the voltage lower limit value, the energy storage device is controlled to discharge to increase the grid-connected voltage. If the over-limit state is higher than the voltage upper limit value, the energy storage device is controlled to charge to reduce the grid-connected voltage.

[0088] In specific implementation, the principle of voltage regulation by charging and discharging the energy storage device is as follows: when the grid voltage is lower than the aforementioned voltage lower limit, the energy storage device discharges to release active power to increase the grid voltage; conversely, when the grid voltage is higher than the aforementioned voltage upper limit, the energy storage device charges to absorb excess active power of the system to reduce the grid voltage; in this way, the purpose of grid voltage regulation can be achieved; at the same time, this embodiment will monitor the grid voltage in real time during the charging and discharging process, wherein, when the grid voltage is adjusted to within the aforementioned calibrated grid voltage range, charging or discharging can be stopped; at the same time, if the charged power exceeds the maximum power value (which can be pre-set) or the discharged power is lower than the minimum power value, the charging or discharging process is stopped. At this time, it is necessary to re-detect whether the grid voltage after charging or discharging adjustment exceeds the limit, and the process can be, but is not limited to, as shown in the following step S4.

[0089] S4. Determine whether the adjusted grid-connected voltage exceeds the limit; in this embodiment, determine whether the adjusted grid-connected voltage is within the calibrated grid-connected voltage range; if it is not within the calibrated grid-connected voltage range, then it is determined that the adjusted grid-connected voltage exceeds the limit; otherwise, it does not exceed the limit.

[0090] In this embodiment, if the grid-connected voltage still exceeds the limit after adjustment by the energy storage device, a secondary voltage adjustment is required using a photovoltaic inverter, and the process may be, but is not limited to, as shown in the following step S5.

[0091] S5. If so, then according to the adjusted grid-connected voltage, adjust the reactive power of the photovoltaic inverter in the energy storage system of the substation corresponding to any photovoltaic grid-connected point, so as to adjust the adjusted grid-connected voltage to within the calibrated grid-connected voltage range by adjusting the reactive power of the photovoltaic inverter, so as to complete the regulation of the distributed photovoltaic substation voltage after adjustment.

[0092] In specific applications, this embodiment is based on the photovoltaic inverter outputting a certain amount of active power while having a portion of residual capacity to perform grid-connected voltage regulation, that is, the inverter can absorb or emit reactive power, thereby achieving the purpose of regulating the grid-connected point voltage; optionally, the voltage regulation process based on the photovoltaic inverter can be, but is not limited to, as shown in the following steps S51 to S53.

[0093] S51. Obtain the maximum value and the minimum value of the grid-connected voltage, wherein the calibrated grid-connected voltage range is between the maximum value and the minimum value of the grid-connected voltage; in this embodiment, the maximum value and the minimum value of the grid-connected voltage are preset values, which can be specifically set according to actual use; therefore, this embodiment is equivalent to setting a minimum voltage and a maximum voltage allowing photovoltaic access, and then, on this basis, allowing the voltage to fluctuate to a certain extent, thereby setting a calibrated grid-connected voltage range between the minimum voltage and the maximum voltage; in this way, after obtaining the aforementioned data, the reactive power regulation function of the photovoltaic inverter can be constructed based on this, so as to regulate the reactive power of the photovoltaic inverter based on the function; wherein, the construction process of the aforementioned regulation function can be but is not limited to the following step S52.

[0094] S52. Construct a reactive power regulation function based on the maximum grid voltage, the minimum grid voltage, the calibrated grid voltage range and the adjusted grid voltage; in specific implementation, the reactive power regulation function can be constructed according to, for example but not limited to, the following formula (2).

[0095]

[0096] In the above formula (2), Q n represents the reactive power regulation function, Indicates the maximum reactive output capacity of the photovoltaic inverter, U′ pcc represents the adjusted grid-connected voltage, Indicates the minimum value of the grid-connected voltage, Indicates the maximum value of the grid-connected voltage, and Indicates the voltage upper limit and voltage lower limit of the calibration grid voltage range, wherein, when Q n When it is positive, it means that the photovoltaic inverter outputs reactive power. n When it is negative, it means that the PV inverter absorbs reactive power.

[0097] In this way, after constructing the reactive power regulation function based on the aforementioned formula (2), the reactive power of the photovoltaic inverter can be regulated based on it, thereby achieving the purpose of re-regulating the adjusted grid-connected voltage; wherein, the power regulation process can be but is not limited to the following step S53.

[0098] S53. According to the reactive power regulation function, the reactive power of the photovoltaic inverter is adjusted; in specific implementation, it is equivalent to controlling the photovoltaic inverter to output reactive power to support the voltage when the adjusted grid-connected voltage is lower than the voltage lower limit, thereby increasing the adjusted grid-connected voltage; conversely, if the adjusted grid-connected voltage is higher than the voltage upper limit, it is necessary to control the photovoltaic inverter to absorb reactive power to reduce the adjusted grid-connected power supply, thereby preventing overvoltage.

[0099] Therefore, through the aforementioned steps S51 to S53, the secondary regulation of the adjusted grid-connected voltage can be completed, thereby adjusting it to within the calibrated grid-connected voltage range to ensure stable access to the distributed photovoltaic power generation system.

[0100] Furthermore, this embodiment provides a further optimization solution based on the above adjustments, namely:

[0101] In actual use, the aforementioned reactive power regulation can effectively regulate the grid voltage, but the reactive power regulation capability is limited. Therefore, when the grid voltage is too high, reactive power regulation is insufficient to adjust the excessive grid voltage to within the calibrated grid voltage range. Therefore, this embodiment provides a voltage regulation solution that combines active power with reactive power. The specific implementation process is as follows:

[0102] After adjusting the reactive power of the photovoltaic inverter in the energy storage system of the substation corresponding to any photovoltaic grid-connected point, it is also necessary to obtain its latest grid-connected voltage, and then judge again whether the latest grid-connected voltage exceeds the limit (that is, judge whether the latest grid-connected voltage is greater than the voltage upper limit value within the calibrated grid-connected power range), so as to adjust the active + reactive power according to the judgment result, thereby adjusting the grid-connected voltage of any photovoltaic grid-connected point to within the calibrated grid-connected voltage range; wherein, the adjustment process can be but is not limited to the following steps S6 to S10.

[0103] S6. Obtain the latest grid-connected voltage of any of the photovoltaic grid-connected points. In this embodiment, after reactive power adjustment by the photovoltaic inverter, the voltage of any of the photovoltaic grid-connected points collected is the latest grid-connected voltage. Then, continue to determine whether it exceeds the limit, so that voltage adjustment operations can be performed based on the judgment result. The specific process can be, but is not limited to, as shown in the following steps S7 to S10.

[0104] S7. Determine whether the latest grid-connected voltage exceeds the limit. In specific applications, it has been explained above that the aforementioned steps S6 to S10 are mainly aimed at overvoltage behavior. Therefore, it is only necessary to determine whether the latest grid-connected voltage is greater than the voltage upper limit. If it is greater, it is considered to be over-limit. At this time, it is necessary to adjust the active power of the photovoltaic access and, at the same time, combine the photovoltaic inverter to adjust the reactive power. The process can be, but is not limited to, as shown in the following steps S8 to S10.

[0105] S8. If so, the photovoltaic active power of any of the photovoltaic grid-connected points is adjusted to the active power upper limit value, and after the photovoltaic active power is adjusted to the active power upper limit value, the output active power of the photovoltaic inverter is obtained; in this embodiment, if the latest grid-connected voltage exceeds the limit, it means that when the reactive power absorption capacity of the photovoltaic inverter reaches the maximum, it is still unable to adjust the voltage to the calibrated grid-connected voltage range. At this time, it is necessary to limit the power connected to the distribution network, that is, to adjust the photovoltaic active power of any of the photovoltaic grid-connected points to the active power upper limit value.

[0106] Optionally, the upper limit of active power can be pre-set; specifically, the increase in photovoltaic active power is positively correlated with the increase in grid-connected voltage, that is, as the connected photovoltaic active power increases, the grid-connected voltage also increases; therefore, the historical grid-connected voltage and the historical photovoltaic active power can be obtained, and then a function image between the historical photovoltaic active power and the historical grid-connected voltage is generated; then, the slope is calculated based on the function image; then, the slope is multiplied by the maximum grid-connected voltage to obtain the maximum active power; finally, the upper limit of active power is set based on the maximum active power (usually less than the maximum active power).

[0107] In this way, after limiting the active power of the distributed photovoltaic power generation system connected to the distribution network through the aforementioned step S8, the latest grid-connected voltage of any photovoltaic grid-connected point can be reduced; then, the output active power of the photovoltaic inverter at this time can be obtained, and then the maximum reactive output capacity is updated, and reactive adjustment is performed again, so as to adjust the latest grid-connected voltage to within the calibrated grid-connected voltage range; wherein, the updating process of the maximum reactive output capacity can be, but is not limited to, as shown in the following step S9.

[0108] S9. Based on the output active power and in accordance with the following formula (3), the maximum reactive output capacity of the photovoltaic inverter is updated to obtain the updated maximum reactive output capacity.

[0109] Q n ' max =P s tan[arccos(δ)] (3)

[0110] In the above formula (3), Q n ' max Represents the updated maximum reactive output capacity, P s represents the output active power, and δ represents a power control factor. In this embodiment, the power control factor is a constant.

[0111] Therefore, based on the above formula (3), the maximum reactive output capacity of the photovoltaic inverter can be updated; finally, the voltage can be adjusted in combination with the latest grid-connected voltage, and the process can be but not limited to the following step S10.

[0112] S10. According to the updated maximum reactive output capacity and the latest grid-connected voltage, the reactive power of the photovoltaic inverter is adjusted to adjust the latest grid-connected voltage to within the calibrated grid-connected voltage range by adjusting the reactive power of the photovoltaic inverter. In this embodiment, the aforementioned latest grid-connected voltage is essentially the voltage collected by any photovoltaic grid-connected point after the photovoltaic active power is adjusted to the active power upper limit. At this time, Q in the aforementioned formula (2) is n max Replace with Q n ' max Then, the reactive power is adjusted according to the aforementioned formula (2); thus, after the aforementioned adjustment, the voltage of any photovoltaic grid-connected point can be adjusted to within the aforementioned calibrated grid-connected voltage range, thereby ensuring the stable access of the distributed photovoltaic power generation system.

[0113] Of course, the adjustment process of the grid-connected voltage of the remaining photovoltaic grid-connected points in the distribution network is the same as the adjustment process of the grid-connected voltage of any of the aforementioned photovoltaic grid-connected points, and will not be repeated here.

[0114] Therefore, through the above detailed explanation of the distributed photovoltaic substation voltage control method, the present invention performs the initial regulation of the photovoltaic grid-connected point voltage through the charging and discharging of the energy storage equipment in the substation energy storage system in the distribution network, and then combines it with the photovoltaic inverter in the distribution network to achieve secondary regulation of the photovoltaic grid-connected point voltage, thereby adjusting it to within the calibrated grid-connected voltage range to ensure the stable access of the distributed photovoltaic power generation system; thus, the present invention can solve the problem that the voltage deviation abnormality caused by the access of the distributed photovoltaic power generation system to the distribution network leads to voltage over-limit, thereby improving the power quality of the local load and the penetration rate of photovoltaics in the distribution network; therefore, it is very suitable for large-scale application and promotion.

[0115] like Figure 2 As shown, the second aspect of this embodiment provides a hardware device for implementing the distributed photovoltaic area voltage control method described in the first aspect of the embodiment, including:

[0116] The acquisition unit is used to obtain the grid-connected power parameters of any photovoltaic grid-connected point in the distribution network.

[0117] A judgment unit is used to judge whether the grid-connected voltage of any photovoltaic grid-connected point exceeds a limit according to the grid-connected power parameter.

[0118] The charging and discharging control unit is used to control the energy storage device in the energy storage system of the corresponding substation of any photovoltaic grid-connected point to charge or discharge when the judgment unit determines that the grid-connected voltage exceeds the limit, so as to adjust the grid-connected voltage by charging or discharging the energy storage device to obtain the adjusted grid-connected voltage.

[0119] The judging unit is further configured to judge whether the adjusted grid-connected voltage exceeds a limit.

[0120] The inverter control unit is used to adjust the reactive power of the photovoltaic inverter in the energy storage system of the substation corresponding to any photovoltaic grid-connected point according to the adjusted grid-connected voltage when the judgment unit determines that the adjusted grid-connected voltage exceeds the limit, so as to adjust the adjusted grid-connected voltage to within the calibrated grid-connected voltage range by adjusting the reactive power of the photovoltaic inverter, so as to complete the regulation of the distributed photovoltaic substation voltage after adjustment.

[0121] The working process, working details and technical effects of the device provided in this embodiment can be found in the first aspect of the embodiment and will not be described in detail here.

[0122] like Figure 3 As shown, the third aspect of this embodiment provides another distributed photovoltaic area voltage control device, taking the device as an electronic device as an example, including: a memory, a processor and a transceiver that are communicatively connected in sequence, wherein the memory is used to store computer programs, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute the distributed photovoltaic area voltage control method as described in the first aspect of the embodiment.

[0123] For example, the memory may include, but is not limited to, random access memory (RAM), read-only memory (ROM), flash memory, first-in-first-out memory (FIFO), and / or first-in-last-out memory (FILO). Specifically, the processor may include one or more processing cores, such as a quad-core processor or an octa-core processor. The processor may be implemented in at least one hardware form selected from the group consisting of a DSP (Digital Signal Processing), an FPGA (Field-Programmable Gate Array), and a PLA (Programmable Logic Array). Furthermore, the processor may include a main processor and a coprocessor. The main processor is a processor for processing data in an awake state, also known as a CPU (Central Processing Unit); and the coprocessor is a low-power processor for processing data in a standby state.

[0124] In some embodiments, the processor may be integrated with a GPU (Graphics Processing Unit, image processor), which is responsible for rendering and drawing the content required to be displayed on the display screen. For example, the processor may be limited to a microprocessor of the STM32F105 series, a reduced instruction set computer (RISC) microprocessor, an X86 architecture processor, or an integrated embedded neural network processor (NPU); the transceiver may be, but is not limited to, a wireless fidelity (WIFI) wireless transceiver, a Bluetooth wireless transceiver, a general packet radio service technology (GPRS) wireless transceiver, a ZigBee protocol (a low-power local area network protocol based on the IEEE 802.15.4 standard, ZigBee) wireless transceiver, a 3G transceiver, a 4G transceiver, and / or a 5G transceiver. In addition, the device may also include, but is not limited to, a power module, a display screen, and other necessary components.

[0125] The working process, working details and technical effects of the electronic device provided in this embodiment can be found in the first aspect of the embodiment and will not be described in detail here.

[0126] The fourth aspect of this embodiment provides a storage medium that stores instructions for the distributed photovoltaic area voltage control method described in the first aspect of the embodiment, that is, the storage medium stores instructions, and when the instructions are run on a computer, the distributed photovoltaic area voltage control method described in the first aspect of the embodiment is executed.

[0127] The storage medium refers to a carrier for storing data, which may include but is not limited to a floppy disk, an optical disk, a hard disk, a flash memory, a USB flash drive and / or a memory stick, and the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device.

[0128] The working process, working details and technical effects of the storage medium provided in this embodiment can be found in the first aspect of the embodiment and will not be described in detail here.

[0129] A fifth aspect of this embodiment provides a computer program product comprising instructions, which, when executed on a computer, causes the computer to execute the distributed photovoltaic area voltage control method as described in the first aspect of the embodiment, wherein the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device.

[0130] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A distributed photovoltaic area voltage control method, characterized in that: The method is applied to the energy storage system of the substation corresponding to each photovoltaic grid connection point in the distribution network, wherein the method includes: Obtain grid-connected power parameters of any photovoltaic grid-connected point in the distribution network; Determining whether the grid-connected voltage of any photovoltaic grid-connected point exceeds a limit based on the grid-connected power parameters; If so, controlling the energy storage device in the energy storage system of the corresponding area of ​​any photovoltaic grid-connected point to charge or discharge, so as to adjust the grid-connected voltage by charging or discharging the energy storage device to obtain an adjusted grid-connected voltage; Determining whether the adjusted grid-connected voltage exceeds a limit includes: Determining whether the adjusted grid-connected voltage is within a calibrated grid-connected voltage range; If not, it is determined that the adjusted grid-connected voltage exceeds the limit; Accordingly, adjusting the reactive power of the photovoltaic inverter in the energy storage system in the area corresponding to any photovoltaic grid-connected point according to the adjusted grid-connected voltage includes: Obtaining a maximum grid-connected voltage and a minimum grid-connected voltage, wherein the calibrated grid-connected voltage range is between the maximum grid-connected voltage and the minimum grid-connected voltage; Constructing a reactive power regulation function according to the maximum grid voltage, the minimum grid voltage, the calibrated grid voltage range, and the adjusted grid voltage, including: According to the following formula (2), the reactive power regulation function is constructed; （2） In the above formula (2), represents the reactive power regulation function, Indicates the maximum reactive output capacity of the photovoltaic inverter, represents the adjusted grid-connected voltage, Indicates the minimum value of the grid-connected voltage, Indicates the maximum value of the grid-connected voltage, and Indicates the voltage upper limit and voltage lower limit of the calibration grid voltage range, wherein, when When it is positive, it means the photovoltaic inverter outputs reactive power. When it is negative, it means that the photovoltaic inverter absorbs reactive power; adjusting the reactive power of the photovoltaic inverter according to the reactive power regulation function; If so, the reactive power of the photovoltaic inverter in the energy storage system of the area corresponding to any photovoltaic grid-connected point is adjusted according to the adjusted grid-connected voltage, so as to adjust the adjusted grid-connected voltage to within the calibrated grid-connected voltage range by adjusting the reactive power of the photovoltaic inverter, so as to complete the regulation of the distributed photovoltaic area voltage after adjustment.

2. The method according to claim 1, characterized in that Controlling the energy storage device in the energy storage system of the corresponding area of ​​any photovoltaic grid-connected point to charge or discharge, including: Obtaining the state of charge of the energy storage device, and determining whether the energy storage device has charge and discharge capabilities based on the state of charge; If so, the over-limit status of the grid-connected voltage of any photovoltaic grid-connected point is obtained, and the energy storage device is controlled to charge or discharge according to the over-limit status; otherwise, the reactive power of the photovoltaic inverter in the energy storage system of the substation corresponding to any photovoltaic grid-connected point is adjusted according to the grid-connected voltage, so as to adjust the grid-connected voltage to within the calibrated grid-connected voltage range by adjusting the reactive power of the photovoltaic inverter; Among them, the over-limit state is lower than the voltage lower limit value within the calibrated grid-connected voltage range or higher than the voltage upper limit value within the calibrated grid-connected voltage range, and if the over-limit state is lower than the voltage lower limit value, the energy storage device is controlled to discharge to increase the grid-connected voltage; if the over-limit state is higher than the voltage upper limit value, the energy storage device is controlled to charge to reduce the grid-connected voltage.

3. The method according to claim 1, characterized in that After adjusting the reactive power of the photovoltaic inverter in the energy storage system in the substation corresponding to any photovoltaic grid-connected point, the method further includes: Obtaining the latest grid-connected voltage of any photovoltaic grid-connected point; Determining whether the latest grid-connected voltage exceeds a limit; If so, adjusting the photovoltaic active power of any photovoltaic grid-connected point to the active power upper limit, and after adjusting the photovoltaic active power to the active power upper limit, obtaining the output active power of the photovoltaic inverter; According to the output active power and in accordance with the following formula (3), the maximum reactive output capacity of the photovoltaic inverter is updated to obtain an updated maximum reactive output capacity; （3） In the above formula (3), represents the updated maximum reactive output capacity, represents the output active power, represents the power control factor; The reactive power of the photovoltaic inverter is adjusted according to the updated maximum reactive output capacity and the latest grid-connected voltage, so as to adjust the latest grid-connected voltage to within the calibrated grid-connected voltage range by adjusting the reactive power of the photovoltaic inverter.

4. A distributed photovoltaic area voltage control device, used to implement the distributed photovoltaic area voltage control method according to any one of claims 1 to 3, characterized in that: The device comprises: An acquisition unit, used to obtain grid-connected power parameters of any photovoltaic grid-connected point in the distribution network; a judgment unit, configured to judge whether the grid-connected voltage of any photovoltaic grid-connected point exceeds a limit according to the grid-connected power parameter; a charge and discharge control unit, configured to control the energy storage device in the energy storage system of the corresponding substation of any photovoltaic grid-connected point to charge or discharge when the judgment unit determines that the grid-connected voltage exceeds the limit, so as to adjust the grid-connected voltage by charging or discharging the energy storage device to obtain an adjusted grid-connected voltage; The judging unit is further configured to judge whether the adjusted grid-connected voltage exceeds a limit; The inverter control unit is used to adjust the reactive power of the photovoltaic inverter in the energy storage system of the substation corresponding to any photovoltaic grid-connected point according to the adjusted grid-connected voltage when the judgment unit determines that the adjusted grid-connected voltage exceeds the limit, so as to adjust the adjusted grid-connected voltage to within the calibrated grid-connected voltage range by adjusting the reactive power of the photovoltaic inverter, so as to complete the regulation of the distributed photovoltaic substation voltage after adjustment.

5. An electronic device, characterized in that: include: A memory, a processor, and a transceiver that are sequentially communicatively connected, wherein the memory is used to store a computer program, the transceiver is used to send and receive messages, and the processor is used to read the computer program to execute the distributed photovoltaic area voltage control method as described in any one of claims 1 to 3.

6. A computer program product comprising instructions, characterized in that When the instructions are executed on a computer, the computer is caused to execute the distributed photovoltaic area voltage control method according to any one of claims 1 to 3.

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