An intelligent control method and system based on a photovoltaic grid-connected switch

Abstract

The present application discloses an intelligent control method and system based on a photovoltaic grid-connected switch, relating to the technical field of power supply grid connection control. The method includes: obtaining the grid load and determining whether photovoltaic grid connection is required; if photovoltaic grid connection is required, obtaining the change in light intensity to determine the photovoltaic grid-connected switch time; obtaining the grid access capacity to determine the number of photovoltaic grid-connected switches; obtaining the grid structure of the photovoltaic grid-connected switches to determine the positions of the photovoltaic grid-connected switches; statistically analyzing the influence degree after each photovoltaic grid-connected switch is turned on according to the positions of the photovoltaic grid-connected switches to determine the order of the photovoltaic grid-connected switches; forming an intelligent control scheme for the photovoltaic grid-connected switches according to the photovoltaic grid-connected switch time, the number of photovoltaic grid-connected switches, the positions of the photovoltaic grid-connected switches, and the order of the photovoltaic grid-connected switches, and implementing remote operation according to the intelligent control scheme. The present application improves the accuracy of intelligent control based on photovoltaic grid-connected switches.

Description

Technical Field

[0001] This application relates to the technical field of power supply grid connection control, and in particular to an intelligent control method and system based on a photovoltaic grid connection switch. Background Art

[0002] Photovoltaic grid connection refers to the energy integration process of inputting the electric energy of a renewable energy system with energy conversion function into the power supply grid through the corresponding AC or DC system. This technology combines renewable energy and the existing power network, realizing the extensive utilization of renewable energy. It not only meets the requirements of users for investment savings, convenience and high efficiency of renewable energy, but also conforms to the social needs of energy conservation and environmental protection. The photovoltaic grid connection system has advantages such as high safety, low cost, and environmental friendliness, and can provide more stable energy guarantee for society, reduce greenhouse gas emissions, improve air quality, and effectively improve the current environmental problems. In general photovoltaic grid connection, only one photovoltaic grid connection switch is controlled by one key to achieve photovoltaic grid connection. However, the number of photovoltaic grid connection switches is not fixed. In some large-scale photovoltaic power stations, in order to achieve more effective power management and system protection, multiple grid connection switches are set. And one-key control is not applicable to multiple grid connection switches. One-key control to open multiple grid connection switches is not conducive to the operation of the power grid, making the remote operation of the grid connection switches inaccurate. Summary of the Invention

[0003] The purpose of the present invention is to provide an intelligent control method and system based on a photovoltaic grid connection switch to solve the problems raised in the above background art.

[0004] In the first aspect, an intelligent control method based on a photovoltaic grid connection switch provided by this application adopts the following technical solutions:

[0005] Obtain the grid load, and judge whether photovoltaic grid connection is required according to the grid load;

[0006] If photovoltaic grid connection is required, obtain the change situation of the light intensity, and determine the photovoltaic grid connection switch time according to the change situation of the light intensity;

[0007] Obtain the grid access capacity, and determine the number of photovoltaic grid connection switches in combination with the photovoltaic grid connection switch time and the grid access capacity;

[0008] Obtain the grid structure of the photovoltaic grid connection switch, and determine the position of the photovoltaic grid connection switch according to the grid structure and the number of photovoltaic grid connection switches;

[0009] Statistically analyze the influence degree after each photovoltaic grid connection switch is turned on according to the position of the photovoltaic grid connection switch, and determine the order of the photovoltaic grid connection switches according to the influence degree;

[0010] Form an intelligent control plan for the photovoltaic grid-connected switch according to the photovoltaic grid-connected switch time, the number of photovoltaic grid-connected switches, the positions of the photovoltaic grid-connected switches, and the order of the photovoltaic grid-connected switches, and implement remote operation according to the intelligent control plan.

[0011] Preferably, the step of obtaining the change of light intensity and determining the photovoltaic grid-connected switch time according to the change of light intensity when photovoltaic grid connection is required is specifically as follows:

[0012] Obtain the change of light intensity in the photovoltaic power generation area, predict the photovoltaic power generation amount at different time points according to the change of light intensity, and form a photovoltaic power generation amount curve;

[0013] Obtain the historical electricity consumption record, extract the change of electricity load according to the historical electricity consumption record, and form an electricity load curve;

[0014] Set the standard load corresponding to the photovoltaic power generation amount, and form a corresponding standard load curve according to the photovoltaic power generation amount curve and the corresponding standard load;

[0015] Combine the electricity load curve and the standard load curve, calculate the load difference, set a load difference threshold, and select the time points where the load difference is not greater than the load difference threshold as the standard time points;

[0016] Form a collection of the standard time points without time intervals to obtain multiple time collections, count the duration of the time collections, and use the time collections whose duration exceeds the preset duration threshold as the photovoltaic grid-connected switch time.

[0017] Preferably, the step of obtaining the grid access capacity and determining the number of photovoltaic grid-connected switches in combination with the photovoltaic grid-connected switch time is specifically as follows:

[0018] Extract the photovoltaic power generation amount curve corresponding to the photovoltaic grid-connected switch time and record it as the grid-connected power generation amount, and obtain the photovoltaic power generation capacity according to the grid-connected power generation amount;

[0019] Obtain the maximum access capacity of the grid, and determine the first number of switches in combination with the photovoltaic power generation capacity;

[0020] Obtain the resonance interference intensity, and find the corresponding second number of switches according to the preset resonance interference intensity - number of switches table;

[0021] Combine the first number of switches and the second number of switches, and analyze to obtain the number of photovoltaic grid-connected switches.

[0022] Preferably, the step of obtaining the maximum access capacity of the grid and determining the first number of switches in combination with the photovoltaic power generation capacity is specifically as follows:

[0023] Judge whether the grid will have an overload situation according to the maximum access capacity and the photovoltaic power generation capacity;

[0024] If an overload situation occurs, calculate the average power generation capacity corresponding to the grid connection switch, and combine it with the maximum access capacity to obtain the threshold of the number of PV grid connection switches;

[0025] Calculate the average power consumption load according to the power consumption load curve, statistically calculate the average power generation of the grid connection switch, and combine the average power consumption load and the average power generation to obtain the standard number of switches;

[0026] If the standard number of switches is not greater than the threshold of the number of PV grid connection switches, then use the standard number of switches as the first number of switches;

[0027] If the standard number of switches is greater than the threshold of the number of PV grid connection switches, then use the threshold of the number of PV grid connection switches as the first number of switches;

[0028] If no overload situation occurs, then use the standard number of switches as the first number of switches.

[0029] Preferably, the step of analyzing and obtaining the number of PV grid connection switches by combining the first number of switches and the second number of switches is specifically as follows:

[0030] Judge whether the first number of switches is not less than the second number of switches. If the first number of switches is not less than the second number of switches, then use the first number of switches as the number of PV grid connection switches;

[0031] If the first number of switches is less than the second number of switches, then judge whether the first number of switches is the threshold of the number of PV grid connection switches;

[0032] If it is the threshold of the number of PV grid connection switches, then use the first number of switches as the number of PV grid connection switches;

[0033] If it is not the threshold of the number of PV grid connection switches, then set the quantity weight ratio of the first number of switches and the second number of switches, and calculate the number of PV grid connection switches according to the first number of switches, the second number of switches and the corresponding quantity weight ratio.

[0034] Preferably, the step of obtaining the grid structure of the PV grid connection switch and determining the position of the PV grid connection switch according to the grid structure and the number of PV grid connection switches is specifically as follows:

[0035] Take the position where the PV grid connection switch is located as the grid connection point position to form a grid connection point position map;

[0036] Obtain the grid structure layout map, and obtain the grid area corresponding to the grid connection point according to the grid connection point position map and the grid structure layout map;

[0037] Obtain the regional access capacity of the grid area, obtain the power generation capacity of the grid connection point and record it as the switch power generation capacity, and screen and remove the grid connection points where the switch power generation capacity is greater than the corresponding regional access capacity to obtain the primary grid connection points;

[0038] Obtain the power generation of the grid connection point and record it as the switch power generation, and obtain the corresponding switch load according to the switch power generation;

[0039] Obtain the regional load of the power grid area, calculate the difference between the switch load and the regional load and record it as the first difference, set the first difference threshold, screen and remove the primary grid connection points where the first difference is greater than the difference threshold, and obtain the intermediate grid connection points;

[0040] Evaluate the grid connection success rate and grid connection safety rate of the intermediate grid connection points, respectively set the grid connection weight ratios of the grid connection success rate and the grid connection safety rate, and calculate the grid connection adaptation rate according to the grid connection success rate, the grid connection safety rate and the corresponding grid connection weight ratios;

[0041] Sort the intermediate grid connection points in descending order according to the grid connection adaptation rate, select the corresponding number of intermediate grid connection points at the front of the sorting according to the number of photovoltaic grid connection switches and record them as the high-level grid connection points, and use the switches of the high-level grid connection points as the positions of the photovoltaic grid connection switches.

[0042] Preferably, the step of evaluating the grid connection success rate and grid connection safety rate of the intermediate grid connection points is specifically:

[0043] Obtain the environmental data of the intermediate grid connection points, and the environmental data includes temperature, humidity and wind speed;

[0044] Obtain the surface temperature of the photovoltaic panels caused by the temperature, obtain the reduced temperature of the photovoltaic panels with reduced wind speed according to the wind speed, and superimpose the surface temperature and the reduced temperature to obtain the actual temperature of the photovoltaic panels;

[0045] Obtain the temperature threshold that affects the power generation performance, judge whether the actual temperature reaches the temperature threshold, and if it reaches the temperature threshold, calculate the temperature difference between the actual temperature and the temperature threshold;

[0046] Obtain the humidity threshold that affects the power generation efficiency, judge whether the humidity reaches the humidity threshold, and if it reaches the humidity threshold, calculate the humidity difference between the humidity and the humidity threshold;

[0047] Respectively set the difference weight ratios of the temperature difference and the humidity difference, and calculate the grid connection success rate according to the temperature difference, the humidity difference and the corresponding difference weight ratios.

[0048] Preferably, the step of evaluating the grid connection success rate and grid connection safety rate of the intermediate grid connection points is specifically:

[0049] Obtain the grid access point corresponding to the intermediate grid connection point and record it as the intermediate access point, and obtain the structural firmness of the power grid area corresponding to the intermediate access point;

[0050] Obtain the voltage fluctuation frequency and harmonic content of the generated electric energy of the intermediate grid connection point to evaluate the power quality;

[0051] Obtain the grid stability degree of the intermediate access point, and calculate the grid connection safety rate by combining the structural strength and power quality.

[0052] Preferably, the step of statistically analyzing the influence degree after each photovoltaic grid connection switch is opened according to the photovoltaic grid connection switch position, and determining the photovoltaic grid connection switch sequence according to the influence degree is specifically as follows:

[0053] Obtain the importance degree of the high-level access point in the grid structure layout;

[0054] Evaluate the power generation capacity of the high-level grid connection point according to the power generation capacity and power generation amount of the high-level grid connection point;

[0055] Combine the importance degree and the power generation capacity to obtain the influence degree of the high-level access point on the grid;

[0056] Sort according to the influence degree size to obtain the photovoltaic grid connection switch sequence.

[0057] In a second aspect, an intelligent control system based on a photovoltaic grid connection switch provided by the present application adopts the following technical solutions:

[0058] An intelligent control system based on a photovoltaic grid connection switch, comprising:

[0059] A grid connection judgment module, which obtains the grid load and judges whether photovoltaic grid connection is required according to the grid load;

[0060] A switch time module, if photovoltaic grid connection is required, obtains the change situation of the light intensity, and determines the photovoltaic grid connection switch time according to the change situation of the light intensity;

[0061] A switch quantity module, which obtains the grid access capacity, and determines the photovoltaic grid connection switch quantity by combining the photovoltaic grid connection switch time and the grid access capacity;

[0062] A switch position module, which obtains the grid structure of the photovoltaic grid connection switch, and determines the photovoltaic grid connection switch position according to the grid structure and the photovoltaic grid connection switch quantity;

[0063] A switch sequence module, which statistically analyzes the influence degree after each photovoltaic grid connection switch is opened according to the photovoltaic grid connection switch position, and determines the photovoltaic grid connection switch sequence according to the influence degree;

[0064] An intelligent control module, which forms an intelligent control scheme for the photovoltaic grid connection switch according to the photovoltaic grid connection switch time, the photovoltaic grid connection switch quantity, the photovoltaic grid connection switch position and the photovoltaic grid connection switch sequence, and realizes remote operation according to the intelligent control scheme.

[0065] In summary, the present application includes at least one of the following beneficial technical effects:

[0066] 1. Determine the photovoltaic grid-connected switch time through the change of light intensity, determine the number of photovoltaic grid-connected switches according to the grid access capacity, obtain the positions of the photovoltaic grid-connected switches using the grid structure, and obtain the photovoltaic grid switch sequence by combining the influence degree after the switch is turned on, so as to form an intelligent control scheme for the photovoltaic grid-connected switches, which provides convenience for remotely operating the opening of the photovoltaic grid-connected switches. At the same time, the intelligent control scheme is more in line with the actual situation, improving the accuracy of the intelligent control based on the photovoltaic grid-connected switches.

[0067] 2. Use the change of light intensity to confirm the power generation amount and power generation capacity of photovoltaic power generation, combine the grid load changes brought by user electricity consumption, and analyze the suitability of photovoltaic power generation and grid operation at different time periods, so as to determine the appropriate photovoltaic grid-connected switch time. Grid connection is carried out within the appropriate photovoltaic grid-connected switch time, reducing power generation waste and unstable power generation during the grid connection process.

[0068] 3. Analyze the grid connection success rate based on the temperature, humidity and wind speed of the intermediate grid connection point corresponding to the photovoltaic grid-connected switch. Use the structural strength of the grid area corresponding to the intermediate access point, and the power quality evaluated by the voltage fluctuation frequency and harmonic content of the generated electric energy passing through the intermediate grid connection point, combined with the grid stability degree of the intermediate access point, to calculate the grid connection safety rate. Then obtain the grid connection adaptation rate according to the grid connection success rate and the grid connection safety rate, so as to select the photovoltaic grid-connected switch at the appropriate position as the switch to be opened for grid connection subsequently. Effectively improve the grid connection success rate and the grid connection safety rate, and improve the intelligence of the intelligent control based on the photovoltaic grid-connected switches. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 is a schematic diagram of the specific steps of an embodiment of an intelligent control method based on a photovoltaic grid-connected switch of the present invention.

[0070] Figure 2 is a schematic diagram of the module connection of an embodiment of an intelligent control system based on a photovoltaic grid-connected switch of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0071] The following is a further detailed description of the present invention in conjunction with the embodiments and Figure 1 - Figure 2 but the embodiments of the present invention are not limited thereto.

[0072] The present invention discloses an intelligent control method based on a photovoltaic grid-connected switch, which specifically includes the following steps:

[0073] Step S1, obtain the grid load, and determine whether photovoltaic grid connection is required according to the grid load.

[0074] When the power grid can support users' electricity consumption without affecting it, there is naturally no need for PV grid connection. When the power grid has difficulty supporting users' electricity consumption, PV grid connection is required to reduce the impact of power supply on users. Therefore, it is necessary to observe the grid load. For example, summer is the peak electricity consumption season in this area, especially in the afternoon when the grid load reaches its peak. Through real-time monitoring equipment, it is found that the grid load continues to climb during this period, approaching or exceeding the upper limit of the grid capacity. Using historical data and prediction models to predict the grid load during this period, the results show that the grid load will continue to operate at a high level in the afternoon in the next few days. Then it can be known that during the afternoon in summer, the grid load has reached its peak, and PV grid connection is needed to maintain stable power supply to the grid.

[0075] Step S2: If PV grid connection is required, obtain the change in light intensity, and determine the PV grid connection switch time according to the change in light intensity.

[0076] Step S3: Obtain the grid access capacity, and determine the number of PV grid connection switches in combination with the PV grid connection switch time and the grid access capacity.

[0077] Step S4: Obtain the grid structure of the PV grid connection switches, and determine the positions of the PV grid connection switches according to the grid structure and the number of PV grid connection switches.

[0078] Step S5: Statistically analyze the impact degree after each PV grid connection switch is turned on according to the positions of the PV grid connection switches, and determine the order of the PV grid connection switches according to the impact degree.

[0079] Step S6: Form an intelligent control plan for the PV grid connection switches according to the PV grid connection switch time, the number of PV grid connection switches, the positions of the PV grid connection switches, and the order of the PV grid connection switches, and implement remote operation according to the intelligent control plan.

[0080] When the PV grid connection switch time period is reached, turn on the PV grid connection switches at the positions corresponding to the number of PV grid connection switches one by one in the order of the PV grid connection switches through remote operation to achieve PV grid connection.

[0081] In practical applications, the number of PV grid connection switches is not fixed. It depends on the specific scale, design, and grid connection method of the PV power station. In some large-scale PV power stations, in order to achieve more effective power management and system protection, multiple grid connection switches are set. These switches are distributed at different grid connection points or different circuits to control the connection between the PV power station and the grid. Therefore, one-key control is only applicable to the case of one PV grid connection switch. If multiple grid connection switches are turned on simultaneously, on the one hand, the grid may not be able to bear it, and on the other hand, the impact on the grid caused by turning on simultaneously is too large and is likely to cause grid failures. Therefore, when remotely controlling the opening of PV grid connection switches, it is necessary to consider the time, number, position, and order of the opening of PV grid connection switches to achieve a more stable and safe PV grid connection.

[0082] If photovoltaic grid connection is required, the steps of obtaining the change of light intensity and determining the photovoltaic grid connection switch time according to the change of light intensity are as follows:

[0083] Step S21: Obtain the change of light intensity in the photovoltaic power generation area, predict the photovoltaic power generation amount at different time points according to the change of light intensity, and form a photovoltaic power generation amount curve.

[0084] Step S22: Obtain the historical electricity consumption records, extract the change of electricity load according to the historical electricity consumption records, and form an electricity load curve.

[0085] Step S23: Set the standard load corresponding to the photovoltaic power generation amount, and form a corresponding standard load curve according to the photovoltaic power generation amount curve and the corresponding standard load.

[0086] Step S24: Combine the electricity load curve and the standard load curve, calculate the load difference, set the load difference threshold, and select the time points where the load difference is not greater than the load difference threshold as the standard time points.

[0087] Step S25: Form a collection of the standard time points without time intervals to obtain multiple time collections, count the duration of the time collections, and use the time collection whose duration exceeds the preset duration threshold as the photovoltaic grid connection switch time.

[0088] In practical applications, it is not suitable for grid connection at any time. On the one hand, the power grid has a demand for electric energy, and on the other hand, the photovoltaic power generation has sufficient and stable electric energy. The change of light intensity directly affects the output power and stability of the photovoltaic power generation system. Grid connection during periods of high light intensity can ensure that the photovoltaic power generation system operates at a high efficiency. When the grid load is high, it means that users consume more electricity. At this time, the electricity consumption for photovoltaic grid connection can also increase because users can consume and use it. Therefore, there is a corresponding standard load for the photovoltaic power generation amount. When the power generation amount is larger, a larger standard load is required for the power grid to consume the photovoltaic power generation amount without causing waste of the photovoltaic power generation amount. When the difference between the electricity load curve and the standard load curve is larger, it means that the compatibility between the two is lower, and this time period is less suitable for grid connection. For example, if the grid load is low while the photovoltaic power generation amount is high at this time, obviously grid connection will cause waste of electricity. If the grid load is high while the photovoltaic power generation amount is low at this time, obviously grid connection is also difficult to support the electricity consumption of users, and it will also cause fluctuations to the power grid due to grid connection, so it is not suitable for grid connection. Frequent opening and closing of the grid connection switch will also cause fluctuations to the power grid. Therefore, the suitable time points for grid connection should be continuous within a certain time period. For example, from 1 pm to 5 pm is suitable for grid connection, which is a relatively long grid connection time period that meets the regulations. If 8 am is not suitable for grid connection, 9 am is suitable for grid connection, and 10 am is not suitable for grid connection, and a specified time period cannot be formed at this time, so it is not suitable for grid connection from 8 am to 10 am.

[0089] Steps for obtaining the grid connection capacity and determining the number of PV grid connection switches in combination with the PV grid connection switch time and the grid connection capacity are as follows:

[0090] In step S31, extract the PV power generation curve corresponding to the PV grid connection switch time and denote it as the grid-connected power generation, and obtain the PV power generation capacity according to the grid-connected power generation.

[0091] In step S32, obtain the maximum grid connection capacity of the grid, and determine the first number of switches in combination with the PV power generation capacity.

[0092] In step S33, obtain the resonance interference intensity, and find the corresponding second number of switches according to the preset resonance interference intensity - number of switches table.

[0093] The greater the resonance interference intensity, the more PV grid connection switches are required, because increasing the number of PV grid connection switches can reduce the resonance interference.

[0094] In step S34, analyze and obtain the number of PV grid connection switches in combination with the first number of switches and the second number of switches.

[0095] In practical applications, the maximum grid connection capacity of the grid refers to the maximum PV power generation capacity that can be connected to the grid on the premise of safe operation. The PV power generation capacity refers to the maximum value of the electric energy that the power generation equipment can generate within a certain period of time. The more the number of PV grid connection switches, the more PV power generation equipment is connected, and then the power generation capacity will increase. Therefore, the number of PV switches to be opened needs to consider the maximum grid connection capacity of the grid. Grid resonance means that some parameters in the power system are mismatched, resulting in strong resonance phenomena in the system at certain frequencies. When the number of PV grid connection switches increases, it means an increase in the number of grid connection points, and the harmonic sources originally concentrated at a few grid connection points are dispersed to more grid connection points. The increase in the number of grid connection switches will also change the overall impedance characteristics of the grid. The impedance of the grid is one of the important factors affecting resonance. By increasing the number of grid connection switches, the impedance distribution of the grid can be adjusted, making it more difficult for the system to reach the resonance condition, thereby reducing the possibility of resonance occurrence. And a mutual support relationship can be formed among multiple grid connection points, enhancing the overall stability of the grid. When resonance occurs at a certain grid connection point, other grid connection points can provide additional damping effects to suppress the spread and intensification of resonance. Therefore, when setting the number of PV grid connection switches, resonance interference also needs to be considered.

[0096] Steps for obtaining the maximum grid connection capacity of the grid and determining the first number of switches in combination with the PV power generation capacity are as follows:

[0097] In step S321, judge whether the grid will have an overload situation according to the maximum grid connection capacity and the PV power generation capacity.

[0098] Step S322: If an overload situation will occur, calculate the average power generation capacity corresponding to the grid connection switch, and combine it with the maximum access capacity to obtain the threshold of the number of PV grid connection switches.

[0099] Step S323: Calculate the average power consumption load based on the power consumption load curve, statistically calculate the average power generation of the grid connection switch, and combine the average power consumption load and the average power generation to obtain the standard number of switches.

[0100] Step S324: If the standard number of switches is not greater than the threshold of the number of PV grid connection switches, use the standard number of switches as the first number of switches.

[0101] Step S325: If the standard number of switches is greater than the threshold of the number of PV grid connection switches, use the threshold of the number of PV grid connection switches as the first number of switches.

[0102] Step S326: If no overload situation will occur, use the standard number of switches as the first number of switches.

[0103] In practical applications, the access capacity of the power grid is limited. When the PV power generation capacity is greater than the maximum access capacity of the power grid, the power grid will experience an overload phenomenon. Therefore, the number of PV switches should be controlled to ensure that the PV power generation capacity is less than the maximum access capacity of the power grid. The PV power generation should be balanced with the user's power consumption, so as not to cause insufficient power consumption or excessive power generation. Therefore, the required PV power generation switches are judged according to the load situation. If the required standard number of switches is less than the threshold of the number of switches, it means that no overload will occur, and the standard number of switches is used as the first number of switches. When the standard number of switches exceeds the threshold of the number of switches, using the standard number of switches as the first number of switches at this time will cause an overload phenomenon. Therefore, only the threshold of the number of switches can be used as the first number of switches. If no overload phenomenon occurs, it means that even if all PV switches are turned on, the PV power generation capacity is still not greater than the access capacity of the power grid. At this time, no matter what the standard number of switches is, it can be directly used as the first number of switches.

[0104] The steps to analyze and obtain the number of PV grid connection switches by combining the first number of switches and the second number of switches are as follows:

[0105] Step S341: Judge whether the first number of switches is not less than the second number of switches. If the first number of switches is not less than the second number of switches, use the first number of switches as the number of PV grid connection switches.

[0106] Step S342: If the first number of switches is less than the second number of switches, judge whether the first number of switches is the threshold of the number of PV grid connection switches.

[0107] Step S343: If it is the threshold of the number of PV grid connection switches, use the first number of switches as the number of PV grid connection switches.

[0108] Step S344: If it is not the threshold of the number of PV grid - connection switches, set the quantity weight ratio of the first switch quantity and the second switch quantity, and calculate the number of PV grid - connection switches based on the first switch quantity, the second switch quantity, and the corresponding quantity weight ratio.

[0109] In practical applications, the number of grid switches needs to consider the maximum access capacity of the grid and also resonance. If the first switch quantity is not less than the second switch quantity, taking the first switch quantity as the number of PV grid - connection switches indicates that it can not only meet the requirement of reducing resonance but also not exceed the access capacity of the grid. If the first switch quantity is less than the second switch quantity, then by judging whether the first switch quantity is the threshold of the number of PV grid - connection switches, it is determined whether the maximum access capacity of the grid has been reached. If it is the threshold, it means that grid - connection according to the second switch quantity will result in an overload phenomenon, and at this time, only the first switch quantity can be used as the number of PV grid - connection switches. If it is not the threshold, the number of grid switches can still be increased, and at this time, the weight ratio of the two switch quantities is set to calculate the number of PV grid - connection switches.

[0110] The steps of obtaining the grid structure of the PV grid - connection switch and determining the position of the PV grid - connection switch according to the grid structure and the number of PV grid - connection switches are as follows:

[0111] Step S41: Take the position where the PV grid - connection switch is located as the grid - connection point position to form a grid - connection point position map.

[0112] Step S42: Obtain the grid structure layout map, and based on the grid - connection point position map and the grid structure layout map, obtain the grid area corresponding to the grid - connection point.

[0113] Step S43: Obtain the area access capacity of the grid area, obtain the power generation capacity of the grid - connection point and record it as the switch power generation capacity, and screen and remove the grid - connection points where the switch power generation capacity is greater than the corresponding area access capacity to obtain the primary grid - connection points.

[0114] Step S44: Obtain the power generation amount of the grid - connection point and record it as the switch power generation amount, and obtain the corresponding switch load according to the switch power generation amount.

[0115] Step S45: Obtain the area load of the grid area, calculate the difference between the switch load and the area load and record it as the first difference, set the first difference threshold, and screen and remove the primary grid - connection points where the first difference is greater than the difference threshold to obtain the intermediate grid - connection points.

[0116] Step S46: Evaluate the grid - connection success rate and grid - connection safety rate of the intermediate grid - connection points, respectively set the grid - connection weight ratios of the grid - connection success rate and the grid - connection safety rate, and calculate the grid - connection adaptation rate according to the grid - connection success rate, the grid - connection safety rate, and the corresponding grid - connection weight ratios.

[0117] Step S47: Sort the intermediate grid connection points in descending order according to the grid connection adaptation rate. Select the corresponding number of intermediate grid connection points at the front of the sorted list as high-level grid connection points based on the number of PV grid connection switches, and use the switches of the high-level grid connection points as the PV grid connection switch positions.

[0118] In practical applications, after determining the number of grid connection switches, since it is not the total number of all grid connection switches, it is necessary to select switches for grid connection among the grid connection switches. The grid access capacity of each region is different, and the PV power generation capacity of the grid connection points represented by different grid connection switches is also different. Therefore, first exclude the grid connection points that will cause overload. Then remove the grid connection points with too large load difference, that is, the grid connection points where the power generation and power consumption do not match. Then screen the appropriate grid connection points according to the grid connection success rate and grid connection safety rate of different grid connection points to obtain the grid connection switches at the corresponding positions.

[0119] The steps for evaluating the grid connection success rate and grid connection safety rate of the intermediate grid connection points are specifically as follows:

[0120] Step S461: Obtain the environmental data of the intermediate grid connection points. The environmental data includes temperature, humidity, and wind speed.

[0121] Step S462: Obtain the surface temperature of the PV panels caused by the temperature, obtain the reduced temperature of the PV panels with wind speed reduction according to the wind speed, and superimpose the surface temperature and the reduced temperature to obtain the actual temperature of the PV panels.

[0122] Step S463: Obtain the temperature threshold that affects the power generation performance, and judge whether the actual temperature reaches the temperature threshold. If it reaches the temperature threshold, calculate the temperature difference between the actual temperature and the temperature threshold.

[0123] Step S464: Obtain the humidity threshold that affects the power generation efficiency, and judge whether the humidity reaches the humidity threshold. If it reaches the humidity threshold, calculate the humidity difference between the humidity and the humidity threshold.

[0124] Step S465: Set the difference weight ratios of the temperature difference and the humidity difference respectively, and calculate the grid connection success rate according to the temperature difference, the humidity difference, and the corresponding difference weight ratios.

[0125] In actual operation, an increase in temperature will lead to a decrease in the efficiency of photovoltaic panels. When the solar panels are at a high temperature, the conductivity of the semiconductor material will be affected, and the recombination rate of electrons and holes will increase, thereby reducing the conversion efficiency of the photovoltaic panels and increasing the difficulty of grid connection. The influence of wind speed on the photovoltaic system is mainly reflected in two aspects: heat dissipation and stability. An appropriate wind speed can reduce the temperature of the photovoltaic panels and improve the efficiency of the system. In areas with moderate wind, an appropriate wind speed can help the photovoltaic system dissipate heat, reduce the temperature of the panels, and thus improve the power generation efficiency and the success rate of grid connection. For example, in the afternoon of summer, when the temperature of the photovoltaic panels is relatively high, a gentle breeze can quickly reduce their temperature and improve the power generation efficiency. Humidity mainly affects the heat dissipation effect and atmospheric transparency of the photovoltaic system. A higher humidity will cause water accumulation or condensation on the surface of the photovoltaic modules, reducing the light transmittance and thus the power generation efficiency. The power generation efficiency of the photovoltaic power generation system directly affects the stability and reliability of its power generation. If the power generation efficiency fluctuates greatly due to environmental factors such as temperature and humidity, it will lead to unstable power quality output by the photovoltaic power generation system, making it difficult to meet the requirements of the grid for the power quality of grid-connected power. In order to ensure its safe and stable operation, the grid has strict standards and restrictions on the power quality of the output power of grid-connected power sources. The instability of the power generation efficiency of the photovoltaic power generation system may cause it to fail to meet these standards, thus reducing the success rate of grid connection.

[0126] The steps for evaluating the grid connection success rate and grid connection safety rate of the intermediate grid connection point are specifically as follows:

[0127] Step S466: Obtain the grid access point corresponding to the intermediate grid connection point and denote it as the intermediate access point, and obtain the structural firmness of the grid area corresponding to the intermediate access point.

[0128] Step S467: Obtain the voltage fluctuation frequency and harmonic content of the generated electric energy of the intermediate grid connection point, and evaluate the power quality.

[0129] Set the optimal values of the voltage fluctuation frequency and harmonic content of the generated electric energy, and calculate the differences between the voltage fluctuation frequency, harmonic content and the optimal values respectively. The larger the difference, the lower the power quality; the smaller the difference, the higher the power quality.

[0130] Step S468: Obtain the grid stability degree of the intermediate access point, and calculate the grid connection safety rate by combining the structural firmness and power quality.

[0131] In practical applications, the weight ratios of grid stability, structural firmness, and power quality are set respectively, and the grid connection safety rate is calculated based on the grid stability, structural firmness, power quality, and their corresponding weight ratios. Voltage fluctuation means that the voltage value in the power grid changes continuously within a certain range, and this change will cause adverse effects on other devices in the power grid (such as transformers, capacitors, etc.), thereby affecting the stability and safety of the entire power grid. The inverter in the photovoltaic power generation system will generate harmonics during operation. Harmonics are a non-sinusoidal waveform, which will pollute the power grid. The existence of harmonics will increase the reactive power loss in the power grid, reduce the power supply efficiency of the power grid, and make the power grid prone to failures. A firm grid structure usually has a higher redundancy, that is, when some devices or lines fail, other devices or lines can quickly take over the work of the faulty part to ensure the continuous power supply of the power grid. A stable power grid can better protect the devices in the power grid from damage. When a fault occurs in the power grid, a stable power grid can quickly isolate the faulty part and restore power supply, reducing the risk of equipment damage. Ensuring the safety of grid connection is conducive to reducing faults, thereby reducing the inconvenience brought to users due to power grid faults.

[0132] The steps of statistically calculating the influence degree after each photovoltaic grid connection switch is opened according to the position of the photovoltaic grid connection switch and determining the photovoltaic grid connection switch sequence according to the influence degree are specifically as follows:

[0133] Step S51, obtain the importance degree of the high-level access point in the power grid structure layout.

[0134] The grid connection access point corresponding to the high-level grid connection point is denoted as the high-level access point.

[0135] Step S52, evaluate the power generation capacity of the high-level grid connection point according to the power generation capacity and power generation amount of the high-level grid connection point.

[0136] The greater the power generation capacity of the grid connection point, the greater its influence on the power grid. Because a large-capacity photovoltaic power generation system will inject more electric energy into the power grid after grid connection, thus having a greater impact on the voltage, frequency, and stability of the power grid. And the larger the power generation capacity and power generation amount, the stronger the power generation ability.

[0137] Step S53, combine the importance degree and the power generation capacity to obtain the influence degree of the high-level access point on the power grid.

[0138] Step S54, sort according to the size of the influence degree to obtain the photovoltaic grid connection switch sequence.

[0139] In practical applications, the more important the high-level access point is in the power grid, the greater the impact of a fault, and the greater the impact on the power grid. The stronger the power generation capacity of the high-level grid connection point, the greater the impact on the power grid during grid connection. It is preferable to select the grid connection point with a smaller impact for grid connection, which can gradually increase the load of the power grid, avoid excessive impact on the power grid, and improve the safety and stability of the grid connection process.

[0140] An intelligent control system based on a photovoltaic grid connection switch, by applying an intelligent control method based on a photovoltaic grid connection switch as described above, includes:

[0141] A grid connection judgment module, which obtains the power grid load and judges whether photovoltaic grid connection is required according to the power grid load.

[0142] A switch time module, if photovoltaic grid connection is required, obtains the change of light intensity, and determines the photovoltaic grid connection switch time according to the change of light intensity.

[0143] A switch quantity module, which obtains the grid access capacity, and determines the number of photovoltaic grid connection switches in combination with the photovoltaic grid connection switch time and the grid access capacity.

[0144] A switch position module, which obtains the power grid structure of the photovoltaic grid connection switch, and determines the position of the photovoltaic grid connection switch according to the power grid structure and the number of photovoltaic grid connection switches.

[0145] A switch sequence module, which calculates the impact degree after each photovoltaic grid connection switch is turned on according to the position of the photovoltaic grid connection switch, and determines the sequence of the photovoltaic grid connection switches according to the impact degree.

[0146] An intelligent control module, which forms an intelligent control scheme for the photovoltaic grid connection switch according to the photovoltaic grid connection switch time, the number of photovoltaic grid connection switches, the position of the photovoltaic grid connection switch, and the sequence of the photovoltaic grid connection switches, and realizes remote operation according to the intelligent control scheme.

[0147] In practical applications, in some large-scale photovoltaic power stations, in order to achieve more effective power management and system protection, multiple grid connection switches are set. The multiple grid connection switches are controlled by remote operation. What time, in what order, and which position of the grid connection switch is opened are important parts to be considered in grid connection. By means of the change of light intensity, the grid access capacity, the power grid structure, and the impact degree, the opening time, the opening number, the opening position, and the opening order of the photovoltaic grid connection switch are obtained respectively, which provides convenience for remotely operating the opening of the photovoltaic grid connection switch and improves the stability and safety of the photovoltaic grid connection.

[0148] The above are all the preferred embodiments of this application, and the protection scope of this application is not limited by this. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. An intelligent control method based on photovoltaic grid-connected switches, characterized in that: The following steps are involved: Obtain the grid load and determine whether photovoltaic grid connection is required based on the grid load; If photovoltaic grid connection is required, obtain the change of light intensity and determine the photovoltaic grid connection switch time according to the change of light intensity; Obtain the grid access capacity, and determine the number of photovoltaic grid-connected switches based on the photovoltaic grid-connected switch time and the grid access capacity; Obtain the grid structure of the photovoltaic grid-connected switch, and determine the location of the photovoltaic grid-connected switch according to the grid structure and the number of photovoltaic grid-connected switches; According to the location of the photovoltaic grid-connected switches, the impact degree of each photovoltaic grid-connected switch after it is turned on is counted, and the photovoltaic grid-connected switch sequence is determined according to the impact degree; According to the photovoltaic grid-connected switch time, the number of photovoltaic grid-connected switches, the location of photovoltaic grid-connected switches and the photovoltaic grid-connected switch sequence, an intelligent control plan for photovoltaic grid-connected switches is formed, and remote operation is achieved according to the intelligent control plan; The steps of obtaining the change of light intensity if photovoltaic grid connection is required and determining the photovoltaic grid connection switch time according to the change of light intensity are specifically as follows: Obtain the changes in light intensity in the photovoltaic power generation area, predict the photovoltaic power generation at different time points based on the changes in light intensity, and form a photovoltaic power generation curve; Obtain historical electricity consumption records, extract electricity load changes based on the historical electricity consumption records, and form an electricity load curve; Set the standard load corresponding to the photovoltaic power generation, and form a corresponding standard load curve according to the photovoltaic power generation curve and the corresponding standard load; Combine the power load curve and the standard load curve to calculate the load difference, set the load difference threshold, and select the time point when the load difference is not greater than the load difference threshold as the standard time point; The standard time points without time intervals are combined to obtain multiple time collections, the duration of the time collections is counted, and the time collections whose duration exceeds a preset duration threshold are used as photovoltaic grid-connected switching time; The steps of obtaining the grid access capability and determining the number of photovoltaic grid-connected switches in combination with the photovoltaic grid-connected switch time and the grid access capability are specifically as follows: The photovoltaic power generation curve corresponding to the photovoltaic grid-connected switching time is extracted and recorded as the grid-connected power generation, and the photovoltaic power generation capacity is extracted based on the grid-connected power generation; The maximum access capacity of the power grid is obtained, and the first number of switches is determined in combination with the photovoltaic power generation capacity; Obtaining the resonance interference intensity, and finding the corresponding second switch quantity according to a preset resonance interference intensity-switch quantity table; The number of photovoltaic grid-connected switches is analyzed by combining the first number of switches and the second number of switches.

2. The intelligent control method based on photovoltaic grid-connected switches according to claim 1 is characterized in that: The step of obtaining the maximum access capacity of the power grid and determining the first number of switches in combination with the photovoltaic power generation capacity is specifically as follows: Determine whether the grid will be overloaded based on the maximum access capacity and photovoltaic power generation capacity; If an overload situation occurs, the average power generation capacity corresponding to the grid-connected switch is calculated, and combined with the maximum access capacity, the threshold value of the number of photovoltaic grid-connected switches is obtained; The average power load is calculated based on the power load curve, and the average power generation corresponding to the grid-connected switch is statistically calculated. The number of standard switches is obtained by combining the average power load and the average power generation; If the number of standard switches is not greater than the threshold number of photovoltaic grid-connected switches, the number of standard switches is used as the first number of switches; If the number of standard switches is greater than the threshold number of photovoltaic grid-connected switches, the threshold number of photovoltaic grid-connected switches is used as the first number of switches; If no overload situation occurs, the standard switch quantity is used as the first switch quantity.

3. The intelligent control method based on photovoltaic grid-connected switches according to claim 2 is characterized in that: The step of analyzing and obtaining the number of photovoltaic grid-connected switches by combining the first number of switches and the second number of switches is specifically as follows: Determine whether the number of the first switches is not less than the number of the second switches. If the number of the first switches is not less than the number of the second switches, use the number of the first switches as the number of photovoltaic grid-connected switches; If the first switch quantity is less than the second switch quantity, determining whether the first switch quantity is a photovoltaic grid-connected switch quantity threshold; If it is the photovoltaic grid-connected switch quantity threshold, the first switch quantity is used as the photovoltaic grid-connected switch quantity; If it is not the photovoltaic grid-connected switch quantity threshold, a quantity weight ratio between the first switch quantity and the second switch quantity is set, and the photovoltaic grid-connected switch quantity is calculated according to the first switch quantity, the second switch quantity and the corresponding quantity weight ratio.

4. The intelligent control method based on photovoltaic grid-connected switches according to claim 3 is characterized in that: The step of obtaining the grid structure of the photovoltaic grid-connected switch and determining the position of the photovoltaic grid-connected switch according to the grid structure and the number of photovoltaic grid-connected switches is specifically as follows: The location of the photovoltaic grid-connected switch is used as the grid-connected point location to form a grid-connected point location map; Obtain the grid structure layout diagram, and obtain the grid area corresponding to the grid connection point according to the grid connection point location diagram and the grid structure layout diagram; Obtain the regional access capacity of the power grid area, obtain the power generation capacity of the grid connection point and record it as the switch power generation capacity, filter out the grid connection points whose switch power generation capacity is greater than the corresponding regional access capacity, and obtain the primary grid connection point; The power generation of the grid-connected point is obtained and recorded as the switch power generation, and the corresponding switch load is obtained according to the switch power generation; Obtaining the regional load of the power grid area, calculating the difference between the switch load and the regional load and recording it as a first difference, setting a first difference threshold, screening and removing primary grid connection points whose first difference is greater than the difference threshold, and obtaining intermediate grid connection points; Evaluate the grid connection success rate and grid connection safety rate of the intermediate grid connection points, set the grid connection weight ratios of the grid connection success rate and the grid connection safety rate respectively, and calculate the grid connection adaptation rate according to the grid connection success rate, the grid connection safety rate and the corresponding grid connection weight ratio; According to the grid-connected adaptation rate, the intermediate grid-connected points are sorted from large to small. According to the number of photovoltaic grid-connected switches, the intermediate grid-connected points with the corresponding number in front of the sorting are selected and recorded as advanced grid-connected points. The switches of the advanced grid-connected points are used as the photovoltaic grid-connected switch positions.

5. The intelligent control method based on photovoltaic grid-connected switches according to claim 4 is characterized in that: The steps of evaluating the grid connection success rate and grid connection safety rate of the intermediate grid connection point are specifically as follows: Acquiring environmental data of the intermediate grid connection point, the environmental data including temperature, humidity and wind speed; The surface temperature of the photovoltaic panel caused by the temperature is obtained, and the reduced temperature of the photovoltaic panel when the wind speed is reduced is obtained according to the wind speed. The surface temperature and the reduced temperature are superimposed to obtain the actual temperature of the photovoltaic panel; Obtaining a temperature threshold that affects power generation performance, determining whether the actual temperature reaches the temperature threshold, and if so, calculating the temperature difference between the actual temperature and the temperature threshold; Obtaining a humidity threshold that affects power generation efficiency, determining whether the humidity reaches the humidity threshold, and if so, calculating a humidity difference between the humidity and the humidity threshold; The difference weight ratios of the temperature difference and the humidity difference are set respectively, and the grid connection success rate is calculated according to the temperature difference, the humidity difference and the corresponding difference weight ratios.

6. The intelligent control method based on photovoltaic grid-connected switches according to claim 5 is characterized in that: The steps of evaluating the grid connection success rate and grid connection safety rate of the intermediate grid connection point are specifically as follows: Obtain a grid access point corresponding to the intermediate grid connection point and record it as the intermediate access point, and obtain the structural solidity of the grid area corresponding to the intermediate access point; Obtain the voltage fluctuation frequency and harmonic content of the generated electric energy at the intermediate grid connection point to evaluate the power quality; The grid stability of the intermediate access point is obtained, and the grid connection safety rate is calculated based on the structural strength and power quality.

7. The intelligent control method based on photovoltaic grid-connected switches according to claim 6 is characterized in that: The steps of counting the influence degree of each photovoltaic grid-connected switch after it is turned on according to the position of the photovoltaic grid-connected switch and determining the photovoltaic grid-connected switch sequence according to the influence degree are specifically as follows: Obtain the importance of advanced access points in the grid structure layout; Evaluate the generation capacity of advanced grid connection points based on their generation capacity and generation output; The impact of advanced access points on the power grid is obtained by combining importance and power generation capacity; The order of photovoltaic grid-connected switches is obtained by sorting them according to the degree of impact.

8. An intelligent management and control system based on photovoltaic grid-connected switches, characterized in that: By applying an intelligent control method based on a photovoltaic grid-connected switch according to any one of claims 1 to 7, the method comprises: The grid connection judgment module obtains the grid load and determines whether photovoltaic grid connection is required based on the grid load; The switch time module obtains the change of light intensity if photovoltaic grid connection is required, and determines the photovoltaic grid connection switch time according to the change of light intensity; The switch quantity module obtains the grid access capacity and determines the number of photovoltaic grid-connected switches based on the photovoltaic grid-connected switch time and the grid access capacity; The switch position module obtains the grid structure of the photovoltaic grid-connected switch and determines the position of the photovoltaic grid-connected switch according to the grid structure and the number of photovoltaic grid-connected switches; The switch sequence module counts the impact of each photovoltaic grid-connected switch after it is turned on according to the position of the photovoltaic grid-connected switch, and determines the photovoltaic grid-connected switch sequence according to the impact; The intelligent management and control module forms an intelligent management and control plan for photovoltaic grid-connected switches according to the photovoltaic grid-connected switch time, the number of photovoltaic grid-connected switches, the location of photovoltaic grid-connected switches and the sequence of photovoltaic grid-connected switches, and realizes remote operation according to the intelligent management and control plan.

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