Distributed photovoltaic inverter power control method and system suitable for different scenarios

Abstract

This invention provides a distributed photovoltaic inverter power control method and system suitable for different scenarios. This method first determines whether the current voltage adjustment scenario is in effect based on collected basic distribution network data. Then, based on the voltage adjustment scenario, it selects a corresponding distributed photovoltaic inverter output power control strategy to obtain a target output power value for the distributed photovoltaic inverter. Finally, the distributed photovoltaic inverter output power is controlled according to the target output power value. This invention not only enhances the flexibility and accuracy of node voltage adjustment but also effectively promotes friendly interaction between distributed photovoltaic power sources and the power grid, improving the energy efficiency of the entire power system.

Description

Technical Field

[0001] The present invention belongs to the technical field of power distribution network control, and in particular relates to a distributed photovoltaic inverter power control method and system suitable for different scenarios. Background Art

[0002] With growing global awareness of environmental protection and the development of renewable energy technologies, solar photovoltaic power generation has garnered widespread attention as a clean and sustainable form of energy. However, the integration of distributed photovoltaic systems into distribution networks presents new challenges to grid voltage stability due to the volatility and uncertainty of their output power. Ensuring the stable operation of photovoltaic systems and avoiding adverse impacts on the grid, particularly in various voltage regulation scenarios, has become a pressing issue.

[0003] Traditional distributed photovoltaic inverter power control methods mostly use fixed control strategies, such as maximum power point tracking (MPPT) or constant power output mode, which are difficult to adapt to changing voltage environments. In situations where the grid voltage fluctuates significantly or multiple voltage adjustment requirements exist, fixed control strategies often fail to effectively regulate the inverter's output power, resulting in the photovoltaic power generation system being unable to fully realize its efficiency and potentially even impacting the grid. Existing methods that are applicable to both voltage overshoot and voltage fluctuation scenarios often require complex algorithms, making it difficult to achieve dynamic and rapid adjustment of distributed photovoltaic inverter power. Therefore, there is an urgent need for a control method that can simply and quickly adjust the inverter's output power according to the voltage adjustment scenario, thereby enabling intelligent management and optimized operation of photovoltaic power generation systems. Summary of the Invention

[0004] The purpose of the present invention is to address the above-mentioned problems existing in the prior art and to provide a distributed photovoltaic inverter power control method and system applicable to different scenarios.

[0005] To achieve the above objectives, the technical solutions of the present invention are as follows:

[0006] In a first aspect, the present invention proposes a distributed photovoltaic inverter power control method applicable to different scenarios, comprising:

[0007] S1. Determine whether the current scenario is voltage adjustment based on the collected basic data of the distribution network. If so, proceed to S2, where the voltage adjustment scenario includes a voltage offset scenario and a voltage fluctuation scenario.

[0008] S2. Selecting a corresponding distributed photovoltaic inverter output power control strategy according to the voltage adjustment scenario, thereby obtaining an output power target value of the distributed photovoltaic inverter;

[0009] S3. Control the output power of the distributed photovoltaic inverter according to the output power target value.

[0010] In S2, if the voltage offset scenario occurs, the output power target value of the distributed photovoltaic inverter is calculated according to the following control strategy:

[0011]

[0012] a1=R 2 +X 2

[0013] b1=2A1R

[0014]

[0015] In the above formula, Pdg and Qdg are the output active and reactive power target values ​​of the distributed photovoltaic inverter, a1, b1, c1, and A1 are intermediate parameters, and S N , dg is the capacity of the distributed photovoltaic inverter, R and X are the resistance and reactance of the line where the distributed photovoltaic inverter is located, ΔUdif is the voltage offset required to be adjusted after the distributed power supply is connected, U N is the rated voltage of the line where the distributed photovoltaic inverter is located, Gu is the voltage loss coefficient corresponding to the typical load power distribution mode or the typical power distribution mode, which reflects the relative loss of voltage loss of each distribution mode relative to the terminal centralized distribution mode. Among them, the distribution modes include terminal centralized distribution, uniform distribution, increasing distribution, decreasing distribution and intermediate heavier distribution, which can take values ​​of 1, 0.5, 0.67, 0.33 and 0.5 respectively.

[0016] In S2, if the voltage fluctuates, the output power target value of the distributed photovoltaic inverter is calculated according to the following control strategy:

[0017]

[0018] a2=R 2 +X 2

[0019] b2=2RA2

[0020]

[0021] In the above formula, Pdg and Qdg are the output active and reactive power target values ​​of the distributed photovoltaic inverter, a2, b2, c2, and A2 are intermediate parameters, and S N , dg is the capacity of the distributed photovoltaic inverter, R and X are the line resistance and reactance respectively, Δd b is the value that needs to be adjusted for voltage fluctuation, U Nis the line rated voltage, λ b It is the ratio of the instantaneous change of the output power of the distributed power source to the rated output power, and Gu is the voltage loss coefficient under the corresponding typical load power distribution mode or the typical power supply power distribution mode.

[0022] In S1, the basic data of the distribution network includes the voltage and frequency of the distributed photovoltaic access distribution network.

[0023] In a second aspect, the present invention proposes a distributed photovoltaic inverter power control system applicable to different scenarios, including a voltage adjustment scenario recognition module, an output power target value determination module, and an inverter power control module;

[0024] The voltage adjustment scenario identification module is used to determine whether the current scenario is a voltage adjustment scenario based on the collected basic data of the distribution network, wherein the voltage adjustment scenario includes a voltage offset scenario and a voltage fluctuation scenario;

[0025] The output power target value determination module is used to select a corresponding distributed photovoltaic inverter output power control strategy according to the voltage adjustment scenario, thereby obtaining the output power target value of the distributed photovoltaic inverter;

[0026] The inverter power control module is used to control the output power of the distributed photovoltaic inverter according to the output power target value.

[0027] If the voltage offset scenario occurs, the output power target value determination module calculates the output power target value of the distributed photovoltaic inverter according to the following control strategy:

[0028]

[0029] a1=R 2 +X 2

[0030] b1=2A1R

[0031]

[0032] In the above formula, Pdg and Qdg are the output active and reactive power target values ​​of the distributed photovoltaic inverter, a1, b1, c1, and A1 are intermediate parameters, and S N , dg is the capacity of the distributed photovoltaic inverter, R and X are the resistance and reactance of the line where the distributed photovoltaic inverter is located, ΔUdif is the voltage offset required to be adjusted after the distributed power supply is connected, U N is the rated voltage of the line where the distributed photovoltaic inverter is located, and Gu is the voltage loss coefficient under the corresponding typical load power distribution mode or typical power distribution mode.

[0033] If the voltage fluctuates, the output power target value determination module calculates the output power target value of the distributed photovoltaic inverter according to the following control strategy:

[0034]

[0035] a2=R 2 +X 2

[0036] b2=2RA2

[0037]

[0038] In the above formula, Pdg and Qdg are the output active and reactive power target values ​​of the distributed photovoltaic inverter, a2, b2, c2, and A2 are intermediate parameters, and S N , dg is the capacity of the distributed photovoltaic inverter, R and X are the line resistance and reactance respectively, Δd b is the value that needs to be adjusted for voltage fluctuation, U N is the line rated voltage, λ b It is the ratio of the instantaneous change of the output power of the distributed power source to the rated output power, and Gu is the voltage loss coefficient under the corresponding typical load power distribution mode or the typical power supply power distribution mode.

[0039] The basic data of the distribution network includes the voltage and frequency of the distributed photovoltaic access distribution network.

[0040] In a third aspect, the present invention provides a distributed photovoltaic inverter power control device suitable for different scenarios, including a memory and a processor;

[0041] The memory is configured to store computer program code and transmit the computer program code to the processor;

[0042] The processor is configured to execute the aforementioned method according to the instructions in the computer program code.

[0043] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the aforementioned method when executed by a processor.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention provides a distributed photovoltaic inverter power control method applicable to different scenarios. The method first determines whether the current voltage adjustment scenario is in use based on collected basic data from the distribution network. Then, based on the voltage adjustment scenario, the method selects a corresponding distributed photovoltaic inverter output power control strategy to obtain a target output power value for the distributed photovoltaic inverter. Finally, the method controls the output power of the distributed photovoltaic inverter according to the target output power value. On the one hand, the method flexibly selects corresponding power control strategies for different voltage adjustment scenarios, enhancing the flexibility and accuracy of node voltage adjustment and ensuring the efficient and stable operation of the photovoltaic power generation system. On the other hand, the method can adjust the inverter output power in real time to closely match the grid demand, optimize the grid's power balance, reduce power loss, and improve the energy efficiency of the entire power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of the distribution network with dense access of distributed photovoltaics.

[0047] Figure 2 Schematic diagram of the process of Example 1.

[0048] Figure 3 This is a structural diagram of the system described in Example 2.

[0049] Figure 4 This is a structural block diagram of the device described in Example 3. DETAILED DESCRIPTION

[0050] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] As a typical flexible resource, the reactive power control of distributed photovoltaic inverters is shown in the following diagram: Figure 1 As shown in the dashed box in the figure, it can output reactive power within its reactive power regulation range according to the requirements of reactive power and voltage optimization control. When voltage is low, the PV inverter is adjusted to operate in leading mode, providing reactive power to the system; conversely, it is adjusted to operate in lagging mode, absorbing reactive power from the system. By leveraging the reactive power regulation capabilities of distributed PV inverters in leading or lagging modes, node voltages can be controlled to enhance the distributed PV carrying capacity of the distribution network.

[0052] This paper proposes a distributed photovoltaic inverter power control method suitable for different scenarios. This method flexibly selects appropriate power control strategies for different voltage adjustment scenarios, effectively avoiding the limitations of traditional methods where a single control strategy is difficult to adapt to variable voltage environments, and enhancing the flexibility and accuracy of node voltage adjustment. Furthermore, this method effectively promotes friendly interaction between distributed photovoltaic power sources and the power grid, which is of great significance for promoting the widespread application of photovoltaic power generation and optimizing and upgrading the energy structure.

[0053] Example 1:

[0054] This embodiment takes a typical rural residential load (increasing distribution) as the research object and implements a distributed photovoltaic inverter power control method applicable to different scenarios described in the present invention. Figure 2 The specific steps are as follows:

[0055] 1. Collect basic grid data, including real-time data such as voltage and frequency of distributed photovoltaic access to the distribution network, and operating parameters such as capacity, output power, and reactive power of photovoltaic inverters.

[0056] 2. Determine whether the current scenario is voltage adjustment based on the collected basic data of the distribution network. If so, proceed to step 3, wherein the voltage adjustment scenario includes a voltage offset scenario and a voltage fluctuation scenario.

[0057] In this embodiment, the voltage deviation limit of 10 kV is ±5% of the rated voltage, and the voltage fluctuation limit is 3%. If the limit is exceeded, it is determined to be in a voltage deviation scenario or a voltage fluctuation scenario.

[0058] 3. According to the voltage adjustment scenario, select the corresponding distributed photovoltaic inverter output power control strategy to obtain the output power target value of the distributed photovoltaic inverter.

[0059] The power control strategy includes a power control strategy for a voltage offset scenario and a power control strategy for a voltage fluctuation scenario. The power control strategy for the voltage offset scenario calculates the output power target value of the distributed photovoltaic inverter according to the following formula:

[0060]

[0061] a1=R 2 +X 2

[0062] b1=2A1R

[0063]

[0064] In the above formula, Pdg and Qdg are the output active and reactive power target values ​​of the distributed photovoltaic inverter, a1, b1, c1, and A1 are intermediate parameters, and S N ,dg is the capacity of the distributed photovoltaic inverter, R and X are the resistance and reactance of the line where the distributed photovoltaic inverter is located, respectively, ΔUdif is the voltage offset required to be adjusted after the distributed power supply is connected, which is 2.5% of the rated voltage in this implementation, that is, 0.25kV, U Nis the rated voltage of the line where the distributed photovoltaic inverter is located, Gu is the voltage loss coefficient corresponding to the typical load power distribution mode or the typical power distribution mode, reflecting the relative voltage loss of each distribution mode relative to the terminal centralized distribution mode. The distribution modes include terminal centralized distribution, uniform distribution, increasing distribution, decreasing distribution, and intermediate heavier distribution. The values ​​can be 1, 0.5, 0.67, 0.33, and 0.5 respectively. In this embodiment, the increasing distribution is used, so 0.67 is used.

[0065] The power control strategy for voltage fluctuation scenarios calculates the output power target value of the distributed photovoltaic inverter according to the following formula:

[0066]

[0067] a2=R 2 +X 2

[0068] b2=2RA2

[0069]

[0070] In the above formula, Pdg and Qdg are the output active and reactive power target values ​​of the distributed photovoltaic inverter, a2, b2, c2, and A2 are intermediate parameters, and S N , dg is the capacity of the distributed photovoltaic inverter, R and X are the line resistance and reactance respectively, Δd b is the voltage fluctuation adjustment value, which is 1% in this embodiment. N is the line rated voltage, λ b is the ratio of the instantaneous change in the output power of the distributed power source to the rated output power, Gu is the voltage loss coefficient corresponding to the typical load power distribution mode or the typical power supply power distribution mode, reflecting the relative loss of voltage loss of each distribution mode relative to the terminal concentrated distribution mode. The distribution modes include terminal concentrated distribution, uniform distribution, increasing distribution, decreasing distribution and intermediate heavier distribution, which can take values ​​of 1, 0.5, 0.67, 0.33 and 0.5 respectively. This embodiment is an increasing distribution, so 0.67 is taken.

[0071] 4. Control the output power of the distributed photovoltaic inverter according to the output power target value. This means adjusting the output power of the distributed photovoltaic inverter to the target value through the inverter control system. During the adjustment process, monitor the changes in grid voltage and inverter output power in real time to ensure that the adjustment effect meets the expectations.

[0072] This embodiment calculates the target output power values ​​of distributed photovoltaic inverters for different line loads, conductor types, and line lengths under voltage offset scenarios, including the maximum active power to be emitted and the reactive power to be absorbed. See Table 1 for details:

[0073] Table 1 Target output power values ​​of distributed photovoltaic inverters under voltage offset scenarios Unit: MW, MVar

[0074]

[0075] Note: The correction amount is 0%, which means that when the maximum allowable voltage loss is 7.5%, the voltage deviation caused by the maximum accessible capacity of distributed photovoltaic is less than 5%, and there is no need to adjust the voltage through the photovoltaic inverter.

[0076] Based on the output power target value in Table 1, the voltage offset adjustment value is calculated to be 0.248kV-0.252kV, and the maximum error range does not exceed ±0.002kV, which basically reaches the preset voltage offset adjustment value of 0.25kV.

[0077] This embodiment calculates the target power control values ​​for PV inverters under different DG fluctuation coefficients, line types, and lengths in voltage fluctuation scenarios, including the maximum active power to be emitted and the reactive power to be absorbed. See Table 2 for details:

[0078] Table 2 Target output power values ​​of distributed photovoltaic inverters under voltage fluctuation scenarios Unit: MVA / MW

[0079]

[0080] Based on the output power target value in Table 2, the voltage fluctuation adjustment value is calculated to be 0.98%-1.01%, with a maximum error range of no more than ±2%, which basically reaches the preset voltage fluctuation adjustment value of 1%.

[0081] From the above results, it can be seen that by using the method described in this embodiment to adjust the output power of the distributed photovoltaic inverter, it is possible to effectively control voltage offset and voltage fluctuation.

[0082] Example 2:

[0083] A distributed photovoltaic inverter power control system suitable for different scenarios, such as Figure 3 As shown, it includes a voltage adjustment scenario recognition module, an output power target value determination module, and an inverter power control module.

[0084] The voltage adjustment scenario identification module is used to determine whether the current scenario is a voltage adjustment scenario based on the collected distribution network basic data, wherein the voltage adjustment scenario includes a voltage offset scenario and a voltage fluctuation scenario, and the distribution network basic data includes the voltage and frequency of the distributed photovoltaic access distribution network.

[0085] The output power target value determination module is used to select the corresponding distributed photovoltaic inverter output power control strategy according to the voltage adjustment scenario, thereby obtaining the output power target value of the distributed photovoltaic inverter, wherein,

[0086] If the voltage offset scenario occurs, the output power target value determination module calculates the output power target value of the distributed photovoltaic inverter according to the following control strategy:

[0087]

[0088] a1=R 2 +X 2

[0089] b1=2A1R

[0090]

[0091] In the above formula, Pdg and Qdg are the output active and reactive power target values ​​of the distributed photovoltaic inverter, a1, b1, c1, and A1 are intermediate parameters, and S N , dg is the capacity of the distributed photovoltaic inverter, R and X are the resistance and reactance of the line where the distributed photovoltaic inverter is located, ΔUdif is the voltage offset required to be adjusted after the distributed power supply is connected, U N is the rated voltage of the line where the distributed photovoltaic inverter is located, and Gu is the voltage loss coefficient under the corresponding typical load power distribution mode or typical power distribution mode.

[0092] If the voltage fluctuates, the output power target value determination module calculates the output power target value of the distributed photovoltaic inverter according to the following control strategy:

[0093]

[0094] a2=R 2 +X 2

[0095] b2=2RA2

[0096]

[0097] In the above formula, Pdg and Qdg are the output active and reactive power target values ​​of the distributed photovoltaic inverter, a2, b2, c2, and A2 are intermediate parameters, and S N , dg is the capacity of the distributed photovoltaic inverter, R and X are the line resistance and reactance respectively, Δd b is the value that needs to be adjusted for voltage fluctuation, U N is the line rated voltage, λ bIt is the ratio of the instantaneous change of the output power of the distributed power source to the rated output power, and Gu is the voltage loss coefficient under the corresponding typical load power distribution mode or the typical power supply power distribution mode.

[0098] The inverter power control module is used to control the output power of the distributed photovoltaic inverter according to the output power target value.

[0099] Example 3:

[0100] A distributed photovoltaic inverter power control device suitable for different scenarios, such as Figure 4 As shown, it includes a memory and a processor; the memory is used to store computer program code and transmit the computer program code to the processor; the processor is used to execute the method as described in Example 1 according to the instructions in the computer program code.

[0101] Example 4:

[0102] A computer-readable storage medium stores a computer program, which implements the method described in Example 1 when executed by a processor.

Claims

1. A distributed photovoltaic inverter power control method applicable to different scenarios, characterized in that: The method comprises: S1. Determine whether the current scenario is voltage adjustment based on the collected basic data of the distribution network. If so, proceed to S2, where the voltage adjustment scenario includes a voltage offset scenario and a voltage fluctuation scenario. S2. Select the corresponding distributed photovoltaic inverter output power control strategy according to the voltage adjustment scenario, so as to obtain the output power target value of the distributed photovoltaic inverter, including: If the voltage offset scenario occurs, the output power target value of the distributed photovoltaic inverter is calculated according to the following control strategy: a1=R 2 +X 2 b1=2A1R In the above formula, P dg , Q dg are the output active and reactive power target values ​​of the distributed photovoltaic inverter, a1, b1, c1, and A1 are intermediate parameters, and S N,dg is the capacity of the distributed photovoltaic inverter, R and X are the resistance and reactance of the line where the distributed photovoltaic inverter is located, ΔU dif The voltage deviation caused by the access of distributed power supply needs to be adjusted. U N is the rated voltage of the line where the distributed photovoltaic inverter is located, G u is the voltage loss coefficient corresponding to the typical load power distribution mode or the typical power distribution mode of the power supply; If the voltage fluctuates, the output power target value of the distributed photovoltaic inverter is calculated according to the following control strategy: a2=R 2 +X 2 b2=2RA2 In the above formula, P dg , Q dg are the output active and reactive power target values ​​of the distributed photovoltaic inverter, a2, b2, c2, and A2 are intermediate parameters, and S N,dg is the capacity of the distributed photovoltaic inverter, R and X are the line resistance and reactance respectively, Δd b is the value that needs to be adjusted for voltage fluctuation, U N is the line rated voltage, λ b G is the ratio of the instantaneous change of the output power of the distributed power source to the rated output power. u is the voltage loss coefficient corresponding to the typical load power distribution mode or the typical power distribution mode of the power supply; S3. Control the output power of the distributed photovoltaic inverter according to the output power target value.

2. A distributed photovoltaic inverter power control method applicable to different scenarios according to claim 1, characterized in that: In S1, the basic data of the distribution network includes the voltage and frequency of the distributed photovoltaic access distribution network.

3. A distributed photovoltaic inverter power control system suitable for different scenarios, characterized in that: The system includes a voltage adjustment scenario recognition module, an output power target value determination module, and an inverter power control module; The voltage adjustment scenario identification module is used to determine whether the current scenario is a voltage adjustment scenario based on the collected basic data of the distribution network, wherein the voltage adjustment scenario includes a voltage offset scenario and a voltage fluctuation scenario; The output power target value determination module is used to select a corresponding distributed photovoltaic inverter output power control strategy according to the voltage adjustment scenario, thereby obtaining the output power target value of the distributed photovoltaic inverter, including: If the voltage offset scenario occurs, the output power target value determination module calculates the output power target value of the distributed photovoltaic inverter according to the following control strategy: a1=R 2 +X 2 b1=2A1R In the above formula, P dg , Q dg are the output active and reactive power target values ​​of the distributed photovoltaic inverter, a1, b1, c1, and A1 are intermediate parameters, and S N,dg is the capacity of the distributed photovoltaic inverter, R and X are the resistance and reactance of the line where the distributed photovoltaic inverter is located, ΔU dif The voltage deviation caused by the access of distributed power supply needs to be adjusted. U N is the rated voltage of the line where the distributed photovoltaic inverter is located, G u is the voltage loss coefficient corresponding to the typical load power distribution mode or the typical power distribution mode of the power supply; If the voltage fluctuates, the output power target value determination module calculates the output power target value of the distributed photovoltaic inverter according to the following control strategy: a2=R 2 +X 2 b2=2RA2 In the above formula, P dg , Q dg are the output active and reactive power target values ​​of the distributed photovoltaic inverter, a2, b2, c2, and A2 are intermediate parameters, and S N,dg is the capacity of the distributed photovoltaic inverter, R and X are the line resistance and reactance respectively, Δd b is the value that needs to be adjusted for voltage fluctuation, U N is the line rated voltage, λ b G is the ratio of the instantaneous change of the output power of the distributed power source to the rated output power. u is the voltage loss coefficient corresponding to the typical load power distribution mode or the typical power distribution mode of the power supply; The inverter power control module is used to control the output power of the distributed photovoltaic inverter according to the output power target value.

4. A distributed photovoltaic inverter power control system applicable to different scenarios according to claim 3, characterized in that: The basic data of the distribution network includes the voltage and frequency of the distributed photovoltaic access distribution network.

5. A distributed photovoltaic inverter power control device suitable for different scenarios, characterized in that: The device includes a memory and a processor; The memory is configured to store computer program code and transmit the computer program code to the processor; The processor is configured to execute the method according to any one of claims 1 to 2 according to instructions in the computer program code.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 2 is implemented.

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