Multi-distributed photovoltaic voltage coordination control method for low-observability power distribution network

Abstract

The invention relates to the technical field of power distribution network photovoltaic power generation voltage control, and discloses a low-observability power distribution network multi-distributed photovoltaic voltage coordination control method, which comprises photovoltaic panel absorbance coordination control, reactive voltage coordination control and absorbance and voltage feedback. The photovoltaic panel absorbance coordination control is used for adjusting the optimal absorbance angle of the photovoltaic panel in each time interval, and the reactive voltage coordination control is used for adjusting and controlling the photovoltaic voltage through the SCADA power monitoring system, the reactive coordination controller and the communication system. According to the technical scheme, adjustment can be carried out according to the optimal light irradiation angle of the photovoltaic panel in each time period, the light-to-electricity efficiency in each time period is ensured, the stability of the photovoltaic voltage of the photovoltaic power station is ensured, more reasonable reactive power distribution can be obtained through reactive voltage coordination control of the photovoltaic power station, and the power efficiency of the photovoltaic power station is improved. The method has good feasibility for multi-distributed photovoltaic voltage control of the low-observability power distribution network.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation voltage control in distribution networks, and specifically provides a method for coordinated voltage control of multiple distributed photovoltaics in a low-observability distribution network. Background Art

[0002] Distributed photovoltaic power generation specifically refers to photovoltaic power generation facilities built near user sites, with the operation mode of self-consumption by users at the user side and excess electricity fed into the grid, and characterized by balance adjustment in the distribution system. Distributed photovoltaic power generation follows the principles of adapting to local conditions, being clean and efficient, having a decentralized layout, and being utilized nearby, making full use of local solar energy resources to replace and reduce fossil energy consumption. Distributed photovoltaic power generation specifically refers to a distributed power generation system that uses photovoltaic modules to directly convert solar energy into electricity; it is a new type of power generation and comprehensive energy utilization method with broad development prospects. It advocates the principles of generating electricity nearby, connecting to the grid nearby, converting nearby, and using nearby. It can not only effectively increase the power generation of photovoltaic power plants of the same scale, but also effectively solve the problem of power loss during voltage boosting and long-distance power transmission; before the power generated by multiple distributed photovoltaics is transported to a low-observability distribution network, voltage coordination control needs to be carried out between the photovoltaic power plant and the low-observability distribution network so that the transmitted power reaches the required interval voltage of the distribution network.

[0003] However, for large-scale multiple distributed photovoltaic power plants, the commonly adopted operation mode is grid-connected operation with constant power. Theoretically, there is a reactive power exchange process with the grid where it is located. However, there are reactive power loss problems during operation, and a more reasonable reactive power distribution cannot be obtained, resulting in insufficient feasibility of coordinated voltage control for multiple distributed photovoltaics in a low-observability distribution network. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for coordinated voltage control of multiple distributed photovoltaics in a low-observability distribution network, which solves the problems presented in the background art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: A method for coordinated voltage control of multiple distributed photovoltaics in a low-observability distribution network, where the coordinated control method includes coordinated control of the light absorption rate of photovoltaic panels, reactive power voltage coordinated control, and feedback of light absorption rate and voltage; The coordinated control of the light absorption rate of photovoltaic panels is used to adjust the optimal light absorption rate angle of photovoltaic panels in each time interval; The reactive power voltage coordinated control adjusts and controls the photovoltaic voltage through a SCADA power monitoring system, a reactive power coordination controller, and a communication system; The feedback of light absorption rate and voltage feeds back the optimal light absorption rate angle of the photovoltaic panel and the actual unregulated voltage, and calculates the loss rate of the photovoltaic panel.

[0006] As a further solution of the present invention: The coordinated control of the light absorption rate of the photovoltaic panels specifically includes the following steps: Step 1: Install angle adjustment components and light absorption rate detection components for multiple distributed photovoltaic panels, connect each photovoltaic panel to the grid, and set the position interval matrix distribution for the multiple distributed photovoltaic panels; Step 2: Adjust the angles of each photovoltaic panel at a time period of 30 minutes through the angle adjustment components, and detect the light absorption rate A of the photovoltaic panels at each angle through the light absorption rate detection components; Step 3: Select the optimal angle of the photovoltaic panel when A is the highest within one time period. Similarly, select the optimal angles of the photovoltaic panels within each time period in turn for cloud storage to ensure that the maximum light-to-electricity conversion efficiency is achieved for the multiple distributed photovoltaic panels within each time period.

[0007] The angle adjustment components and light absorption rate detection components of the multiple distributed photovoltaic panels can be adjusted according to the optimal light irradiation angles of the photovoltaic panels within each time period to ensure the light-to-electricity conversion efficiency within each time period, and the matrix-distributed photovoltaic panels facilitate the control and management of the optimal light irradiation angles of each photovoltaic panel.

[0008] As a still further solution of the present invention: The reactive voltage coordinated control includes the following steps: S1: Install current and voltage transformers on the grid connection of the multiple distributed photovoltaic panels, measure the voltage and current, upload the sampled values to the SCADA power monitoring system, compare the power deviation, set the allowable voltage error deviation for comparison, calculate the impedance X between the photovoltaic power station and the power grid, and calculate the reactive power target value of the photovoltaic power station; S2: Judge the difference between the detected voltage fluctuation and the allowable voltage deviation during a short circuit. If so, immediately enter the economic voltage control strategy. Otherwise, coordinate the control of the voltage according to the reactive power target value through the distribution strategy for photovoltaic inverters, capacitors, etc.; S3: If the voltage fluctuation detected in S2 above is within the allowable voltage deviation during a short circuit, no reactive voltage adjustment is required; S4: If the voltage fluctuation detected in S2 above exceeds the allowable voltage deviation during a short circuit, calculate the total reactive power capacity range of the photovoltaic inverters, SVC reactive power compensation devices, and capacitors, calculate the reactive power increment, and achieve reactive voltage adjustment through photovoltaic transformers, capacitor banks, SVC reactive power compensation devices, and tap changers.

[0009] The coordinated control center composed of the SCADA power monitoring system, the reactive power coordination controller and the communication system adjusts and controls the photovoltaic voltage. The photovoltaic transformer, the capacitor bank, the SVC reactive power compensation device and the tap changer realize the reactive power voltage regulation to ensure the stability of the photovoltaic voltage of the photovoltaic power station. The reactive power voltage coordinated control of the photovoltaic power station can obtain a more reasonable reactive power distribution and has a better coordinated control ability for the multi-distributed photovoltaic voltage of the low-observable distribution network.

[0010] As a further solution of the present invention: the light absorption rate and voltage feedback include the following steps: Step 1: The optimal angle of the photovoltaic panel in each time interval for the first time, and the voltage and current values measured by the corresponding current and voltage transformers are transmitted to the cloud as reference parameters; Step 2: The voltage and current values at the optimal angle of the photovoltaic panel in each subsequent time interval are compared with the reference parameters in Step 1 in the corresponding time interval to calculate the loss rate of the photovoltaic panel; Step 3: When the loss rate of the photovoltaic panel reaches 70%, the corresponding photovoltaic panel is marked with a loss limit through matrix distribution design, and the grid connection route of the corresponding photovoltaic panel is closed.

[0011] By monitoring and measuring the comparison between the actual voltage value of each photovoltaic panel and the voltage reference parameter value measured for the first time, and calculating the loss rate of the corresponding photovoltaic panel, it is convenient to replace the photovoltaic panel with a loss limit without affecting the smooth operation of the overall photovoltaic power station.

[0012] As a further solution of the present invention: the angle adjustment component has the functions of horizontal rotation and vertical rotation, and the angle adjustment component is controlled by a wireless terminal.

[0013] Adjust the optimal light irradiation angle of the photovoltaic panel at each time to reduce the influence of the change of the light-to-electricity conversion caused by the change of the sun's position.

[0014] As a further solution of the present invention: the formula for the light absorption rate A of the photovoltaic panel is: Where: A represents the light absorption rate; I represents the transmitted light intensity, that is, the light intensity passing through the glass of the photovoltaic panel; I0 represents the incident light intensity, that is, the light intensity irradiating on the photovoltaic panel.

[0015] As a further solution of the present invention: the power deviation in S1 above , the reactive power target value in S1 above .

[0016] As a further solution of the present invention: the upper capacity limits of the photovoltaic inverter, the SVC reactive power compensation device and the capacitor in S4 above are respectively , and , and the joint position satisfies , and , the reactive power increment of the above-mentioned S4 .

[0017] As a further solution of the present invention: in the above-mentioned S4, if is less than , the reactive power regulation is realized by the photovoltaic inverter. If , the reactive power voltage regulation is jointly realized by the photovoltaic inverter and the SVC reactive power compensation device. If , the reactive power voltage regulation is jointly realized by the photovoltaic transformer, the capacitor bank, the SVC reactive power compensation device and the tap.

[0018] Analyze and calculate the reactive power voltage and the coordinated control of reactive power voltage of the photovoltaic power station, calculate the reactive power demand, and obtain a more reasonable reactive power distribution.

[0019] As a further solution of the present invention: the photovoltaic panel loss rate in the above-mentioned step 3 , where is the voltage value measured in real time, is the voltage reference parameter value measured for the first time.

[0020] Compared with the prior art, the beneficial effects of the technical solution of the present application are as follows: 1. The coordinated control of the light absorption rate of the photovoltaic panel can be adjusted according to the best light irradiation angle of the photovoltaic panel in each time period by installing the angle adjustment component and the light absorption rate detection component of the multi-distributed photovoltaic panel, ensuring the light-to-electricity conversion efficiency in each time period. By setting every 30 minutes as a time period, the influence of the change of the light-to-electricity conversion caused by the change of the sun position is reduced, and the best light irradiation angle of each photovoltaic panel can be conveniently controlled and managed through the matrix distribution of each photovoltaic panel.

[0021] 2. The coordinated control of reactive power voltage adjusts and controls the photovoltaic voltage through the coordinated control center composed of the SCADA power monitoring system, the reactive power coordination controller and the communication system. When the voltage fluctuation exceeds the allowable voltage deviation during short circuit, the reactive power increment is calculated by calculating the total reactive power capacity range of the photovoltaic inverter, the SVC reactive power compensation device and the capacitor. The reactive power voltage regulation is realized through the photovoltaic transformer, the capacitor bank, the SVC reactive power compensation device and the tap, ensuring the stability of the photovoltaic voltage of the photovoltaic power station. The coordinated control of the reactive power voltage of the photovoltaic power station can obtain a more reasonable reactive power distribution, making the method have good feasibility for the multi-distributed photovoltaic voltage control of the low-observable distribution network.

[0022] 3. The light absorption rate and voltage feedback calculate the loss rate of the corresponding photovoltaic panel by comparing the actual voltage value of each photovoltaic panel with the voltage reference parameter value measured for the first time through real-time monitoring, and mark the photovoltaic panel with the loss limit and perform route closing operation through matrix distribution design, which can not only facilitate the replacement of the photovoltaic panel with the loss limit, but also does not affect the smooth operation of the overall photovoltaic power station. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments read in conjunction with the accompanying drawings: Figure 1 It is a flowchart of the coordinated control of the light absorption rate of the photovoltaic panel of the present invention; Figure 2 It is a flowchart of the reactive voltage coordinated control of the present invention; Figure 3 It is a flowchart of the light absorption rate and voltage feedback of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application. Embodiment

[0025] The present invention provides a coordinated control method for the voltage of multiple distributed photovoltaics in a low-observable distribution network. The coordinated control method includes coordinated control of the light absorption rate of the photovoltaic panel, reactive voltage coordinated control, and light absorption rate and voltage feedback; The coordinated control of the light absorption rate of the photovoltaic panel is used to adjust the optimal light absorption rate angle of each time interval of the photovoltaic panel. The coordinated control of the light absorption rate of the photovoltaic panel specifically includes the following steps: Step 1: Install an angle adjustment component and a light absorption rate detection component for the multiple distributed photovoltaic panels, connect each photovoltaic panel to the grid, and set the position interval matrix distribution for the multiple distributed photovoltaic panels; Step 2: Adjust each photovoltaic panel at different angles with a 30-minute time period through the angle adjustment component, and detect the light absorption rate A of the photovoltaic panel at each angle through the light absorption rate detection component; Step 3: Select the best angle of the photovoltaic panel when A is the highest within one time period. Similarly, select the best angles of the photovoltaic panels within each time period in turn for cloud storage to ensure that the multiple distributed photovoltaic panels achieve the maximum light-to-electricity conversion efficiency within each time period.

[0026] The angle adjustment component has horizontal and vertical rotation functions, and the angle adjustment component is controlled by a wireless terminal; The formula for the light absorption rate A of the photovoltaic panel is: Where: A represents the light absorption rate; I represents the transmitted light intensity, that is, the light intensity passing through the glass of the photovoltaic panel; I0 represents the incident light intensity, that is, the light intensity irradiating on the photovoltaic panel.

[0027] The coordinated control of the light absorption rate of the photovoltaic panel can be adjusted according to the optimal light irradiation angle of the photovoltaic panel in each time period by installing an angle adjustment component and a light absorption rate detection component for multiple distributed photovoltaic panels, ensuring the light-to-electricity conversion efficiency in each time period. By setting every 30 minutes as a time period, the influence of the change in the light-to-electricity conversion caused by the change in the sun's position is reduced, and the control and management of the optimal light irradiation angle of each photovoltaic panel can be facilitated through the matrix distribution setting of each photovoltaic panel. Embodiment

[0028] Based on the first embodiment, the present invention provides a method for coordinated control of the voltage of multiple distributed photovoltaics in a low-observable distribution network. The reactive voltage coordinated control adjusts and controls the photovoltaic voltage through the SCADA power monitoring system, the reactive power coordinated controller, and the communication system. The reactive voltage coordinated control includes the following steps: S1: Install current and voltage transformers on the grid connection of multiple distributed photovoltaic panels, measure the voltage and current, upload the sampled values to the SCADA power monitoring system, compare the power deviation, set the allowable voltage error deviation and compare it, calculate the impedance X between the photovoltaic power station and the power grid, and calculate the reactive power target value of the photovoltaic power station; S2: Judge the difference between the detected voltage fluctuation and the allowable voltage deviation during short circuit. If so, immediately enter the economic voltage control strategy. Otherwise, coordinate the voltage control of the reactive power target value according to the photovoltaic inverter, capacitor, etc. through the distribution strategy; S3: If the voltage fluctuation detected in S2 above is within the allowable voltage deviation during short circuit, no reactive voltage adjustment is required; S4: If the voltage fluctuation detected in S2 above exceeds the allowable voltage deviation during short circuit, calculate the total reactive power capacity range of the photovoltaic inverter, SVC reactive power compensation device, and capacitor, calculate the reactive power increment, and realize reactive voltage adjustment through the photovoltaic transformer, capacitor bank, SVC reactive power compensation device, and tap changer.

[0029] The power deviation in S1 above , the reactive power target value in S1 above ; The upper limits of the capacities of the photovoltaic inverter, SVC reactive power compensation device, and capacitor in S4 above are respectively , and , and the joint position satisfies , and . The reactive power increment of the above-mentioned S4 ; In the above S4, if is less than , the reactive power regulation is achieved by the photovoltaic inverter. If , the reactive power voltage regulation is jointly achieved by the photovoltaic inverter and the SVC reactive power compensation device. If , the reactive power voltage regulation is jointly achieved by the photovoltaic transformer, the capacitor bank, the SVC reactive power compensation device and the tap.

[0030] The reactive power voltage coordinated control adjusts and controls the photovoltaic voltage through a coordinated control center composed of a SCADA power monitoring system, a reactive power coordination controller and a communication system. When the voltage fluctuation exceeds the allowable voltage deviation during short circuit, the reactive power increment is calculated by calculating the total reactive power capacity range of the photovoltaic inverter, the SVC reactive power compensation device and the capacitor, and the reactive power voltage regulation is achieved through the photovoltaic transformer, the capacitor bank, the SVC reactive power compensation device and the tap, ensuring the stability of the photovoltaic voltage of the photovoltaic power station. The reactive power voltage coordinated control of the photovoltaic power station can obtain a more reasonable reactive power distribution, making this method have better feasibility for the voltage control of multiple distributed photovoltaics in a low-observable distribution network.

[0031] Embodiment 3: Based on Embodiment 1 and Embodiment 2, the present invention provides a method for coordinated control of multiple distributed photovoltaic voltages in a low-observable distribution network. The light absorption rate and voltage feedback feedback the optimal light absorption rate angle of the photovoltaic panel and the actual unregulated voltage, and calculate the loss rate of the photovoltaic panel. The light absorption rate and voltage feedback include the following steps: Step 1: The optimal angle of the photovoltaic panel in each time interval for the first time and the voltage and current values measured by the corresponding current and voltage transformers are transmitted to the cloud as reference parameters; Step 2: The voltage and current values at the optimal angle of the photovoltaic panel in each subsequent time interval are compared with the reference parameters in Step 1 in the corresponding time interval, and the loss rate of the photovoltaic panel is calculated; Step 3: When the loss rate of the photovoltaic panel reaches 70%, the corresponding photovoltaic panel is marked with a loss limit through matrix distribution design, and the grid connection route of the corresponding photovoltaic panel is closed.

[0032] The loss rate of the photovoltaic panel in Step 3 above , where is the voltage value measured in real time, is the voltage reference parameter value measured for the first time.

[0033] The light absorption rate and voltage feedback measure the comparison between the actual voltage value of each photovoltaic panel and the voltage reference parameter value measured for the first time through real-time monitoring, calculate the loss rate of the corresponding photovoltaic panel, and perform marking and route closing operations on the photovoltaic panel with the loss limit through matrix distribution design, which can not only facilitate the replacement of the photovoltaic panel with the loss limit, but also does not affect the smooth operation of the overall photovoltaic power station.

[0034] The above are only the preferred embodiments of the present application and are not used to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A multi-distributed photovoltaic voltage coordinated control method for a low-observable distribution network, characterized in that: The coordinated control method includes coordinated control of the light absorption rate of photovoltaic panels, reactive voltage coordinated control, and feedback of light absorption rate and voltage; The coordinated control of the light absorption rate of photovoltaic panels is used to adjust the optimal light absorption rate angle of each time interval of the photovoltaic panels; The reactive voltage coordinated control is composed of a SCADA power monitoring system, a reactive power coordinated controller, and a communication system to adjust and control the photovoltaic voltage; The feedback of light absorption rate and voltage feeds back the optimal light absorption rate angle of the photovoltaic panel and the actual unregulated voltage, and calculates the loss rate of the photovoltaic panel.

2. A low-observable distribution network multi-distributed photovoltaic voltage coordinated control method according to claim 1, characterized in that The coordinated control of the light absorption rate of photovoltaic panels specifically includes the following steps: Step 1: Install an angle adjustment component and a light absorption rate detection component for multi-distributed photovoltaic panels, connect each photovoltaic panel to the grid, and set a position interval matrix distribution for the multi-distributed photovoltaic panels; Step 2: Adjust each photovoltaic panel at different angles with a time period of 30 minutes through the angle adjustment component, and detect the light absorption rate A of the photovoltaic panel at each angle through the light absorption rate detection component; Step 3: Select the optimal angle of the photovoltaic panel when A is the highest within one time period. Similarly, select the optimal angles of the photovoltaic panels within each time period in turn for cloud storage to ensure that the multi-distributed photovoltaic panels achieve the maximum light-to-electricity conversion efficiency within each time period.

3. A low-observable distribution network multi-distributed photovoltaic voltage coordinated control method according to claim 1, characterized in that The reactive voltage coordinated control includes the following steps: S1: Install current and voltage transformers on the grid connection of multi-distributed photovoltaic panels, measure the voltage and current, upload the sampled values to the SCADA power monitoring system, compare the power deviation, set the allowable voltage error deviation and compare it, calculate the impedance X between the photovoltaic power station and the power grid, and calculate the reactive power target value of the photovoltaic power station; S2: Judge the difference between the detected voltage fluctuation and the allowable voltage deviation during short circuit. If so, immediately enter the economic voltage control strategy. Otherwise, coordinate the voltage of the reactive power target value according to the photovoltaic inverter, capacitor, etc. through the distribution strategy; S3: If the voltage fluctuation detected in S2 above is within the allowable voltage deviation during short circuit, no reactive voltage adjustment is required; S4: If the voltage fluctuation detected in S2 above exceeds the allowable voltage deviation during short circuit, calculate the total reactive power capacity range of the photovoltaic inverter, SVC reactive power compensation device, and capacitor, calculate the reactive power increment, and realize reactive voltage adjustment through the photovoltaic transformer, capacitor bank, SVC reactive power compensation device, and tap changer.

4. A low-observable distribution network multi-distributed photovoltaic voltage coordinated control method according to claim 1, characterized in that, The feedback of light absorption rate and voltage includes the following steps: Step 1: Transmit the optimal angle of the photovoltaic panel in each time interval for the first time and the voltage and current values measured by the corresponding current and voltage transformers to the cloud as reference parameters; Step 2: Compare the voltage and current values at the optimal angle of the photovoltaic panel in each subsequent time interval with the reference parameters in Step 1 above in the corresponding time interval, and calculate the loss rate of the photovoltaic panel; Step 3: When the loss rate of the photovoltaic panel reaches 70%, mark the corresponding photovoltaic panel with a loss limit through matrix distribution design, and close the grid connection route of the corresponding photovoltaic panel.

5. A method for coordinated control of voltages of multiple distributed photovoltaics in a low-observable distribution network according to claim 2, characterized in that, The angle adjustment component has horizontal rotation and vertical rotation functions, and the angle adjustment component is controlled by a wireless terminal.

6. A low-observable distribution network multi-distributed photovoltaic voltage coordinated control method according to claim 2, characterized in that The light absorption rate A formula of the photovoltaic panel is as follows: Where: A represents the light absorption rate; $I$ represents the transmitted light intensity, that is, the light intensity passing through the glass of the photovoltaic panel; $I_0$ represents the incident light intensity, that is, the light intensity irradiating on the photovoltaic panel.

7. A low-observable distribution network multi-distributed photovoltaic voltage coordinated control method according to claim 3, characterized in that, The power deviation in S1 described above , the reactive power target value in S1 described above .

8. A method for coordinated voltage control of a low-observable distribution network with multiple distributed photovoltaics according to claim 3, characterized in that The upper limits of the capacities of the photovoltaic inverter, SVC reactive power compensation device, and capacitor in S4 described above are respectively , and , and the joint positions satisfy , and . The reactive power increment of S4 described above is .

9. A low-observable distribution network multi-distributed photovoltaic voltage coordinated control method according to claim 3, characterized in that, In the above-mentioned S4, if less than , reactive power regulation is achieved by the PV inverter. If , reactive power and voltage regulation are jointly achieved by the PV inverter and the SVC reactive power compensation device. If , reactive power and voltage regulation are jointly achieved by the PV transformer, capacitor bank, SVC reactive power compensation device and tap changer.

10. A method for coordinated voltage control of multiple distributed photovoltaics in a low-observable distribution network according to claim 4, characterized in that, The PV panel loss rate in step 3 described above , where is the voltage value measured in real time, is the voltage reference parameter value measured for the first time.

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