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

Abstract

The invention provides a distributed photovoltaic inverter power control method and system suitable for different scenes, and the method comprises the steps: determining whether a current power distribution network is in a voltage adjustment scene or not according to the collected basic data of a power distribution network, and then selecting a corresponding distributed photovoltaic inverter output power control strategy according to the voltage adjustment scene, and finally, the output power of the distributed photovoltaic inverter is controlled according to the output power target value. According to the method, the flexibility and accuracy of node voltage adjustment are enhanced, friendly interaction between the distributed photovoltaic power supply and the power grid is effectively promoted, and the energy efficiency of the whole power system is improved.

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 the increasing global awareness of environmental protection and the development of renewable energy technology, solar photovoltaic power generation has received widespread attention as a clean and sustainable form of energy. However, after the distributed photovoltaic is connected to the distribution network, the volatility and uncertainty of its output power have brought new challenges to the voltage stability of the power grid. Especially in different voltage adjustment scenarios, how to ensure the stable operation of the photovoltaic power generation system and avoid adverse effects on the power grid has become an urgent problem to be solved.

[0003] Traditional distributed photovoltaic inverter power control methods mostly use fixed control strategies, such as maximum power point tracking or constant power output mode, which are difficult to adapt to changing voltage environments. When the grid voltage fluctuates greatly or there are multiple voltage adjustment requirements, fixed control strategies often cannot effectively adjust the output power of the inverter, resulting in the photovoltaic power generation system being unable to fully exert its efficiency and may even cause an impact on the grid. Known methods that are applicable to both voltage over-limit and voltage fluctuation scenarios often require the use of complex algorithms, making it difficult to achieve dynamic and rapid adjustment of the power of distributed photovoltaic inverters. Therefore, there is an urgent need for a control method that can flexibly adjust the inverter output power according to the voltage adjustment scenario in a simple and fast manner, so as to achieve intelligent management and optimized operation of the photovoltaic power generation system. Summary of the invention

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

[0005] To achieve the above objectives, the technical solution of the present invention is 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 situation is a voltage adjustment scenario according to the collected basic data of the distribution network. If so, proceed to S2, wherein the voltage adjustment scenario includes a voltage offset scenario and a voltage fluctuation scenario;

[0008] S2. 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;

[0009] S3. Controlling 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 deviation adjustment value caused by the access of the distributed power source, 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 concentrated distribution mode, wherein 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.

[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 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 suitable for 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 situation is in a voltage adjustment scenario according to 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, so as to obtain 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 is offset, 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 deviation adjustment value caused by the access of the distributed power source, U N is the rated voltage of the line where the distributed photovoltaic inverter is located, and Gu is the voltage loss coefficient corresponding to the typical load power distribution mode or the typical power distribution mode of the power source.

[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 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 include 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 used to store computer program code and transmit the computer program code to the processor;

[0042] The processor is used 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 suitable for different scenarios. The method first determines whether the current voltage adjustment scenario is in accordance with the collected basic data of the distribution network, and then selects 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, and finally controls the output power of the distributed photovoltaic inverter according to the output power target value. On the one hand, the method flexibly selects the corresponding power control strategy for different voltage adjustment scenarios, enhances the flexibility and accuracy of node voltage adjustment, and ensures 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, closely match the power grid demand, optimize the power balance of the power grid, reduce power loss, and improve the energy efficiency of the entire power system. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0047] Figure 2 The figure is a schematic diagram of the process of the method described in 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 is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0051] As a typical flexible resource, the reactive power control of distributed photovoltaic inverters is shown in the following figure: Figure 1 As shown in the dotted box in , it can output reactive power within its reactive power regulation range according to the reactive power voltage optimization control requirements. When the voltage is low, the photovoltaic inverter is adjusted to operate in the leading mode to provide reactive power to the system; conversely, it is adjusted to operate in the lagging mode to absorb reactive power from the system. The reactive power regulation capability of the distributed photovoltaic inverter in the leading or lagging operation mode is used to control the node voltage to improve the distributed photovoltaic carrying capacity of the distribution network.

[0052] The present invention proposes a distributed photovoltaic inverter power control method suitable for different scenarios. The method flexibly selects corresponding power control strategies for different voltage adjustment scenarios, effectively avoiding the limitation that a single control strategy in the traditional method is difficult to adapt to a variable voltage environment, and enhancing the flexibility and accuracy of node voltage adjustment. In addition, the method can effectively promote the friendly interaction between distributed photovoltaic power sources and power grids, which is of great significance to promoting the widespread application of photovoltaic power generation and the optimization and upgrading of energy structure.

[0053] Embodiment 1:

[0054] This embodiment takes a typical rural resident 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 As shown, 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 working parameters such as capacity, output power, and reactive power of photovoltaic inverters.

[0056] 2. Determine whether the current scenario is a voltage adjustment scenario 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 deviation adjustment value caused by the access of the distributed power source, which is 2.5% of the rated voltage in this implementation, i.e. 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, which reflects 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 be 1, 0.5, 0.67, 0.33 and 0.5 respectively. This embodiment is an increasing distribution, so 0.67 is taken;

[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, U 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, that is, adjust 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 the grid voltage and the inverter output power in real time to ensure that the adjustment effect meets expectations.

[0072] This embodiment calculates the target output power values ​​of distributed photovoltaic inverters for different line loads, conductor models and line lengths under the voltage offset scenario, including the maximum active power to be emitted and the reactive power to be absorbed, as shown in Table 1:

[0073] Table 1 Output power target values ​​of distributed photovoltaic inverters under voltage deviation scenarios Units: 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 photovoltaics 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 power control target values ​​of the photovoltaic inverters with different DG fluctuation coefficients, line models and lengths under voltage fluctuation scenarios, including the maximum active power to be emitted and the reactive power to be absorbed, as shown in Table 2:

[0078] Table 2 Output power target 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%, and the maximum error range does not exceed ±2%, which basically reaches the preset voltage fluctuation adjustment value of 1%.

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

[0082] Embodiment 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 it is currently in 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, and the basic data of the distribution network includes the voltage and frequency of the distributed photovoltaic access to the 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, so as to obtain the output power target value of the distributed photovoltaic inverter, wherein:

[0086] If the voltage is offset, 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 deviation adjustment value caused by the access of the distributed power source, U N is the rated voltage of the line where the distributed photovoltaic inverter is located, and Gu is the voltage loss coefficient corresponding to the typical load power distribution mode or the typical power distribution mode of the power source.

[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 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] Embodiment 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] Embodiment 4:

[0102] A computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the method described in Embodiment 1 when executed by a processor.

Claims

1. A distributed photovoltaic inverter power control method suitable for different scenarios, characterized in that: The method comprises: S1. Determine whether the current situation is a voltage adjustment scenario according to the collected basic data of the distribution network. If so, proceed to S2, wherein the voltage adjustment scenario includes a voltage offset scenario and a voltage fluctuation scenario; S2. 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; S3. Controlling 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 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: a1=R 2 +X 2 b1=2A1R 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 deviation adjustment value caused by the access of the distributed power source, U N is the rated voltage of the line where the distributed photovoltaic inverter is located, and Gu is the voltage loss coefficient corresponding to the typical load power distribution mode or the typical power distribution mode of the power source.

3. A distributed photovoltaic inverter power control method applicable to different scenarios according to claim 1 or 2, characterized in that: In S2, 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, 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 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.

4. A distributed photovoltaic inverter power control method applicable to different scenarios according to claim 1 or 2, characterized in that: In S1, 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 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 situation is in a voltage adjustment scenario according to 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, so as to obtain the output power target value of the distributed photovoltaic inverter; The inverter power control module is used to control the output power of the distributed photovoltaic inverter according to the output power target value.

6. A distributed photovoltaic inverter power control system suitable for different scenarios according to claim 5, characterized in that: If the voltage is offset, 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, 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 deviation adjustment value caused by the access of the distributed power source, U N is the rated voltage of the line where the distributed photovoltaic inverter is located, and Gu is the voltage loss coefficient corresponding to the typical load power distribution mode or the typical power distribution mode of the power source.

7. A distributed photovoltaic inverter power control system suitable for different scenarios according to claim 5 or 6, characterized in that: 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, 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 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.

8. A distributed photovoltaic inverter power control system suitable for different scenarios according to claim 5 or 6, characterized in that: The basic data of the distribution network include the voltage and frequency of the distributed photovoltaic access distribution network.

9. A distributed photovoltaic inverter power control device suitable for different scenarios, characterized in that: The device comprises 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 configured to execute the method according to any one of claims 1 to 4 according to instructions in the computer program code.

10. 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 4 is implemented.

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