Photovoltaic power station grid-connected operation comprehensive performance evaluation method

Abstract

The invention provides a photovoltaic power station grid-connected operation comprehensive performance evaluation method, and relates to the technical field of photovoltaic power station grid connection. Grid-connected points of a photovoltaic power station and a power grid are obtained, areas are divided according to power grid distribution, and voltage and current of each sub-area power grid are obtained to form a power grid data matrix; the method comprises the following steps: calculating a regional scheduling coefficient according to a power grid data matrix after grid connection of a photovoltaic power station, calculating a scheduling electric quantity proportion according to power grid voltage and current data, judging a power grid voltage fluctuation stability coefficient, scoring the whole regional scheduling, obtaining continuous voltage data at the same time interval, scoring accurate coordination, and determining the power grid voltage fluctuation stability coefficient. And evaluating an influence coefficient during closing according to the voltage distribution in the power grid data matrix and the adjustment parameters of the inverter, obtaining an initial power grid parameter when the photovoltaic power station is not connected to the grid as a weight distribution reference, and evaluating the comprehensive operation performance.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power station grid connection, and in particular to a method for evaluating the comprehensive performance of photovoltaic power station grid connection operation. Background Art

[0002] With the continuous expansion of photovoltaic power generation, grid-connected photovoltaic power stations have become a crucial component of power system operation. However, because the output power of photovoltaic power stations is significantly affected by environmental variations (such as sunlight and temperature), they can easily cause grid voltage fluctuations, frequency deviations, and insufficient reactive power regulation, which in turn impacts grid stability and dispatchability. Existing technologies primarily evaluate grid-connected performance through single-point monitoring or simple power statistics. There is a lack of methods to systematically evaluate the comprehensive grid-connected performance of photovoltaic power stations based on time-series data, comprehensively considering multi-dimensional indicators such as voltage and current fluctuations, phase deviation, and inverter dynamic response. This results in incomplete and delayed evaluation results, making it difficult to accurately reflect the dynamic adaptability and coordinated dispatch capabilities of photovoltaic power stations to the grid.

[0003] At the same time, some current PV power plant operation evaluation methods often overlook the fundamental parameters of the grid itself before grid connection, as well as the extent to which the inverter affects grid oscillations after grid connection, and are unable to effectively distinguish the actual changes brought about by grid connection. This evaluation method is particularly difficult to adapt to complex multi-regional grid environments, making it difficult to provide a scientific basis for optimizing grid operation and scheduling and adjusting PV power plant control strategies. Therefore, a comprehensive evaluation method that combines regional grid time series data, dynamic scheduling characteristics, and inverter response characteristics is urgently needed to comprehensively and accurately reflect the overall operational performance of PV power plants after grid connection.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0005] The object of the present invention is to provide a method for evaluating the comprehensive performance of grid-connected operation of a photovoltaic power station, so as to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions: A method for evaluating the comprehensive performance of grid-connected operation of a photovoltaic power station, comprising the following steps: Step 1: Divide the area where the PV power station dispatches power to the grid into multiple sub-areas based on the distribution of the grid. Obtain the voltage and current of the grid in each sub-area, stamp them with timestamps to form time series data, and sample them at the same time interval. The voltage and current sampled in each sub-area correspond to a matrix element, forming a grid data matrix that is mapped one-to-one with the location of the sub-area. Step 2: Obtain the grid data matrix after the PV power station is connected to the grid, determine the real-time dispatch area based on the voltage distribution, calculate the regional dispatch coefficient based on the real-time dispatch area, calculate the dispatch power ratio based on the grid voltage and current, determine the grid voltage fluctuation stability coefficient by analyzing the continuous grid data matrix, and score the regional dispatch of the power dispatch area; Step 3: Obtain real-time voltage data from the grid and inverter after the PV power station is connected to the grid, filter it, and calculate the leading or lagging phase deviation, frequency tracking error, and amplitude accumulation difference based on the voltage data at the same consecutive time intervals, and score the precise coordination. Step 4: Based on the voltage distribution in the grid data matrix at each time interval before and after the PV power station is connected to the grid, calculate the oscillation coefficient of the grid after grid connection. Calculate the inverter response coefficient based on the inverter adjustment parameters after grid connection. Evaluate the impact coefficient during closing based on the oscillation coefficient and response coefficient. Step 5: Obtain the initial grid parameters when the PV power station is not connected to the grid as a reference for weight distribution, and evaluate the comprehensive operating performance of the PV power station when it is connected to the grid based on the regional dispatch score, precise coordination score, and switching comprehensive score.

[0007] Furthermore, the real-time dispatching area range is determined based on the voltage distribution, and the specific method for calculating the regional dispatching coefficient based on the real-time dispatching area range is as follows: The lowest voltage value closest to the photovoltaic power station grid connection point in the upstream direction of the current transmission direction of the power grid is the equipotential value, and all equipotential values are connected with the photovoltaic power station grid connection point as the center to form an equipotential line. The area within the equipotential line is the dispatching area range. The specific calculation formula is: ,in, is the regional scheduling coefficient, This is the standard power supply area for photovoltaic power stations. The first The area of the sub-region, is the number of sub-regions within the equipotential line; The calculation method for the dispatch power ratio is: ,in, is the dispatching power ratio, are the voltage and current output by the photovoltaic power station, For the dispatch area Input voltage and input current, is the total circuit quantity of input voltage and input current, For the dispatch area Output voltage and output current, is the total number of circuits with output voltage and output current; The method for determining the grid voltage fluctuation stability coefficient by analyzing the continuous grid data matrix is: The voltage change difference is calculated for the grid data matrix of adjacent time intervals within the dispatching area. Based on the continuous voltage change of each sub-area, the voltage fluctuation stability coefficient of the entire area is calculated: ,in, is the voltage fluctuation stability coefficient, The number of consecutively sampled data, For sub-region The voltage change at each moment, is the mean value of continuous voltage change, is the number of sub-regions within the equipotential line, The first sub-areas.

[0008] Furthermore, the method for scoring the regional dispatch of the power dispatch area is as follows: ,in, Score the regional dispatch, are the weights of regional dispatch coefficient and voltage fluctuation stability coefficient respectively.

[0009] Furthermore, the voltage data includes phase, frequency and amplitude; The calculation method of the phase deviation is: ,in, is the phase accumulator, for The grid phase at the moment, for Inverter phase at the moment, is the number of continuous voltage data obtained, To obtain the Voltage data; The calculation formula of the frequency tracking error is: ,in, is the frequency tracking error, for The grid frequency at the moment, for Inverter frequency at all times; The calculation method of the cumulative difference in amplitude is: ,in, is the cumulative difference in amplitude, for The grid amplitude at the moment, for Inverter amplitude at the moment.

[0010] Furthermore, the method for scoring precise coordination is: ,in, Scoring for precise coordination, They are the weights of phase deviation, frequency tracking error, and amplitude accumulation difference respectively.

[0011] Furthermore, the calculation method of the oscillation coefficient of the power grid after the grid connection is: Taking the voltage distribution before grid connection as the standard voltage, calculate the deviation of the standard voltage at each time interval. Calculate the oscillation coefficient of the grid by analyzing the continuous deviation of each area: ,in, is the oscillation coefficient of the power grid, is the standard voltage matrix, for The voltage matrix at each moment is: is the deviation matrix from the standard voltage, is the difference of the voltage elements in the deviation difference matrix, is the number of consecutive deviations from the differential voltage, is the number of sub-regions within the equipotential line, The first sub-regions; The formula for calculating the response coefficient of the inverter is: ,in, is the response coefficient of the inverter, is the inverter output voltage after grid connection, To stabilize the output voltage of the inverter when connected to the grid, is the inverter target voltage, The moment when the inverter starts to adjust the voltage. Adjust the voltage stabilization time for the inverter.

[0012] Furthermore, the calculation formula for evaluating the influence coefficient during closing based on the oscillation coefficient and the response coefficient is: ,in, is the influence coefficient, Adjust the base for the oscillation coefficient sensitivity, Adjust the base for the oscillation coefficient limit.

[0013] Furthermore, the initial grid parameters include the power demand of the power dispatching area, the voltage, current, voltage fluctuation amplitude, harmonic distortion rate, and voltage frequency deviation of each sub-area; The method for obtaining the initial grid parameters when the photovoltaic power station is not connected to the grid as a reference for weight distribution is: The dynamic weight of the regional dispatch score is calculated based on the power demand, voltage, and current of the power dispatch area: ,in, Dynamic weights for scoring regional dispatches, The limiting coefficient for the dynamic weight of the regional dispatch score, is the power of the sub-region, is the average value of the electricity in the sub-area, is the balance of power distribution, is the voltage of the sub-region, is the current in the sub-region, For the The amount of electricity in each sub-region, They are the first Row, No. List; The dynamic correction weight of the precise coordination score is calculated based on the fluctuation amplitude of current and voltage, harmonic distortion rate, and frequency deviation of voltage: ,in, Dynamically correct weights for precise coordination scoring, The limiting coefficient for the dynamic correction weight of the precise coordination score, is the voltage fluctuation amplitude in the area of power dispatch, is the standard voltage amplitude, is the harmonic distortion rate, The frequency deviation of the voltage in the area of power dispatch, The standard frequency of the voltage in the area where electricity is dispatched.

[0014] Furthermore, based on the regional dispatch score, precise coordination score, and switching comprehensive score, the calculation formula for evaluating the comprehensive operating performance of the photovoltaic power station when it is connected to the grid is as follows: ,in, is the running comprehensive value, Score the regional dispatch, Scoring for precise coordination, is the influence coefficient, They are the regional scheduling score, precise coordination score, and the weight of the impact coefficient; when When the system is in good condition, in, This parameter is the threshold for judging the system operation status.

[0015] Compared with the prior art, the present invention has the following beneficial effects: By obtaining the grid connection point between the photovoltaic power station and the power grid, dividing the area according to the grid distribution, obtaining the voltage and current of the power grid in each sub-area to form a grid data matrix, calculating the regional dispatch coefficient based on the grid data matrix after the photovoltaic power station is grid-connected, calculating the dispatch power ratio based on the grid voltage and current data, and judging the grid voltage fluctuation stability coefficient, and scoring the overall regional dispatch, obtaining voltage data at the same continuous time interval, calculating the leading or lagging phase deviation, frequency tracking error, and amplitude accumulation difference, and scoring the precise coordination, the voltage distribution in the grid data matrix, and the adjustment parameters of the inverter are used to evaluate the influence coefficient when closing the switch, obtaining the initial grid parameters when the photovoltaic power station is not grid-connected as a reference for weight distribution, and evaluating the comprehensive operating performance; By constructing a grid data matrix and performing continuous time-series analysis, this method not only captures the voltage and current variation characteristics of each sub-region after a photovoltaic power station is connected to the grid in real time, but also dynamically evaluates the grid's stability and dispatchability based on the dispatch voltage distribution line and dispatch coefficient, significantly improving the accuracy of comprehensive performance evaluation. By quantifying the phase deviation, frequency tracking error, and cumulative amplitude difference of the inverter voltage data, it effectively reflects the photovoltaic power station's ability to accurately coordinate with the grid during the grid connection process, compensating for the problem of traditional methods that ignore dynamic response characteristics. This invention also establishes a comprehensive scoring system based on weighted distribution by combining initial pre-connection grid parameters. This allows for a more scientific assessment of the impact of post-connection PV power stations on grid oscillations and the inverter's response, providing a comprehensive operational performance indicator system. Compared to existing technologies, this not only achieves higher-precision PV grid-connected performance evaluation but also provides an important basis for optimizing grid-side operational scheduling and adjusting PV power station control strategies, demonstrating promising engineering application value and widespread adoption. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the overall method of the present invention. DETAILED DESCRIPTION

[0017] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0018] It should be noted that, unless otherwise defined, the technical or scientific terms used in the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0019] Example

[0020] See also Figure 1 , the present invention provides a technical solution: A method for evaluating the comprehensive performance of grid-connected operation of a photovoltaic power station, comprising the following steps: Step 1: Divide the area where the photovoltaic power station dispatches electricity to the grid into multiple sub-areas based on the distribution of the grid. Obtain the voltage and current of the grid in each sub-area, stamp them with timestamps to form time series data, and sample them at the same time interval. The voltage and current sampled in each sub-area correspond to a matrix element, forming a grid data matrix that is mapped one-to-one with the position of the sub-area.

[0021] The grid's side length is set based on the grid's geographic distribution and topology. The grid size is determined by the grid layout and the length of its lines. This ensures that the grid lines or substations within each grid are appropriately sized and do not cross multiple grid lines. Using the PV plant's grid connection point as the center of the regional division, grid-based techniques (such as grid-based spatial analysis methods) are used to divide the grid's coverage area into multiple smaller grids. Each grid area contains a single grid line (such as a single transmission line or a substation within a region). If multiple grid lines intersect, the grid boundaries can be adjusted to ensure that each grid contains only one grid line or node. The grid lines or substations within each grid area are mapped into a data matrix, forming a gridded grid data structure. In this matrix, each grid cell represents a single grid line, and the values in the matrix represent the voltage, current, and other status information of the grid line.

[0022] By acquiring voltage, current, and other data from each sub-region and adding timestamps to them to form time-series data, we can accurately capture the grid's state changes at every moment. This time-series data provides rich information for subsequent analysis and accurately reflects the dynamic characteristics of the grid over different time periods. Especially during grid state changes after a PV power station is connected to the grid, voltage and current fluctuations can affect grid stability. Therefore, real-time data sampling allows for more precise tracking of these fluctuations and assessment of the PV station's impact on the grid.

[0023] By comprehensively collecting and analyzing time-series data, the present invention can reveal the changing trends of voltage and current in various regions of the power grid after a photovoltaic power station is connected to the grid. Combined with grid distribution information, the dispatch voltage distribution line can be dynamically calculated, further determining parameters such as regional dispatch coefficients and power ratios, providing data support for subsequent grid dispatch optimization. Specifically, different regions of the power grid have different power demands and power outputs. By dividing the regions, the operating status of the power grid in each region can be accurately assessed, determining whether dispatch adjustments are necessary, and avoiding unnecessary impacts of photovoltaic power stations on the power grid.

[0024] In this embodiment, the grid data matrix is expressed as follows: ,in, is the matrix element, are the voltage and current of the power grid, is the power grid data matrix, The first Row, No. Matrix elements of columns.

[0025] Step 2: Obtain the grid data matrix after the PV power station is connected to the grid, determine the real-time dispatch area based on the voltage distribution, calculate the regional dispatch coefficient based on the real-time dispatch area, calculate the dispatch power ratio based on the grid voltage and current, determine the grid voltage fluctuation stability coefficient by analyzing the continuous grid data matrix, and score the regional dispatch of the power dispatch area.

[0026] In this embodiment, the specific method for calculating the dispatching area range based on the dispatching voltage distribution line is: The lowest voltage value closest to the photovoltaic power station grid connection point in the upstream direction of the current transmission direction of the power grid is the equipotential value, and all equipotential values are connected with the photovoltaic power station grid connection point as the center to form an equipotential line. The area within the equipotential line is the dispatching area range. The specific calculation formula is: ,in, is the regional scheduling coefficient, This is the standard power supply area for photovoltaic power stations. The first The area of the sub-region, is the number of sub-regions within the equipotential line.

[0027] The regional dispatch coefficient reflects the proportion of electricity required to be dispatched within a specific area of the power grid, based on the voltage distribution after a PV power station is connected to the grid, and is a measure of grid stability. By calculating the dispatch coefficient, we can accurately understand the voltage variations and current transmission efficiency in each area of the grid after a PV power station is connected, thereby ensuring the rationality and effectiveness of grid dispatch. The dispatch coefficient is closely related not only to voltage fluctuations but also to factors such as current transmission direction and load distribution. It can help power dispatchers make more precise and dynamic dispatch decisions.

[0028] The calculation method for the dispatch power ratio is: ,in, is the dispatching power ratio, are the voltage and current output by the photovoltaic power station, For the dispatch area Input voltage and input current, is the total circuit quantity of input voltage and input current, For the dispatch area Output voltage and output current, is the total circuit quantity of output voltage and output current.

[0029] The dispatched power ratio refers to the proportion of dispatched power in each region to the total power, calculated based on grid voltage and current data after the PV power station is connected to the grid. It reflects the power allocation of each region within the overall dispatch plan. By determining the dispatched power required for each region, we can ensure the rational distribution of PV power generation within the grid, avoid over-reliance on certain regions, and ensure optimal use of power resources. This can prevent overload or underload in certain areas of the grid, reduce imbalances in grid operation, and enhance grid stability.

[0030] The method of determining the grid voltage fluctuation stability coefficient by analyzing a continuous matrix is: The voltage change difference is calculated for the grid data matrix of adjacent time intervals within the dispatching area. Based on the continuous voltage change of each sub-area, the voltage fluctuation stability coefficient of the entire area is calculated: ,in, is the voltage fluctuation stability coefficient, The number of consecutively sampled data, For sub-region The voltage change at each moment, is the mean value of continuous voltage change, is the number of sub-regions within the equipotential line, The first sub-regions; The grid voltage fluctuation stability coefficient evaluates the stability of voltage fluctuations during the grid dispatch process by analyzing the grid voltage changes over consecutive time intervals. This coefficient reflects the degree of voltage fluctuation and system stability under different dispatch schemes.

[0031] In this embodiment, the method for scoring the regional scheduling of the power scheduling area is: ,in, Score the regional dispatch, are the weights of regional dispatch coefficient and voltage fluctuation stability coefficient respectively.

[0032] Scoring overall regional dispatch involves evaluating the grid's dispatch effectiveness and stability based on the grid data matrix after the PV power station is connected to the grid. This analysis combines parameters such as the dispatch voltage distribution line, regional dispatch coefficient, dispatched power ratio, and the grid voltage fluctuation stability coefficient to assess the grid's dispatch effectiveness and stability, and assigns a comprehensive evaluation score. Scoring overall regional dispatch is crucial for the comprehensive performance evaluation of PV power station grid-connected operations. It not only quantifies the effectiveness of grid dispatch, helping grid operators optimize dispatch strategies and improve grid stability, security, and operational efficiency, but also promotes the development of intelligent and automated grid dispatch. Furthermore, the scoring system enables grid dispatchers to monitor the grid's operating status in real time and make timely adjustments based on the scoring results, ensuring seamless integration between PV power stations and the grid and promoting efficient and stable system operation.

[0033] Step 3: Obtain the real-time voltage data of the grid and inverter after the PV power station is connected to the grid, filter it, and calculate the leading or lagging phase deviation, frequency tracking error, and amplitude accumulation difference based on the voltage data at the same continuous time interval, and score the precise coordination.

[0034] Select a low-pass filter, such as an FIR filter or Kalman filter, and input the collected signal into a digital low-pass filter to obtain a smoothed voltage waveform. This filter preserves the fundamental component of the voltage signal while suppressing high-frequency noise and harmonics. By smoothing the voltage data, the filter can reduce errors in the calculation process. For example, when calculating the frequency and phase deviation between the power grid and the inverter, the smoothed signal better reflects the actual grid characteristics. This reduces the calculated error, improves system accuracy, and reduces the computational burden of the control system.

[0035] In this embodiment, the voltage data includes phase, frequency and amplitude; The calculation method of the phase deviation is: ,in, is the phase accumulator, for The grid phase at the moment, for Inverter phase at the moment, is the number of continuous voltage data obtained, To obtain the Voltage data.

[0036] Phase deviation refers to the phase difference between the grid voltage and the inverter output voltage. Ideally, the grid and inverter outputs should be synchronized, with the voltage waveforms aligned in phase. If the inverter output voltage leads or lags the grid voltage, power transmission efficiency will decrease and may even generate harmonics or cause system instability. Calculating phase deviation quantifies the synchronization between the grid and inverter, identifying and assessing the risk of power loss, fluctuations, or system instability caused by phase deviation. A large system phase deviation indicates coordination issues, potentially impacting grid stability. Conversely, a small phase deviation indicates good system synchronization, with the grid and inverter working in perfect harmony, contributing to stable grid connection for the PV power plant.

[0037] The calculation formula of the frequency tracking error is: ,in, is the frequency tracking error, for The grid frequency at the moment, for Inverter frequency at the moment.

[0038] Frequency tracking error indicates the deviation between the inverter's output frequency and the grid frequency. The grid frequency is typically fixed, and the inverter's output frequency must remain consistent with it to ensure seamless grid integration of the PV power plant. The calculation of frequency tracking error reflects the inverter's accuracy in tracking the grid frequency. Accurate frequency tracking ensures that the PV power plant's output frequency is consistent with the grid frequency, thereby reducing frequency fluctuations and ensuring grid stability.

[0039] A smaller frequency tracking error indicates that the inverter’s control system is accurate, can better adapt to grid frequency changes, and improve the coordination and stability between the photovoltaic power station and the grid.

[0040] The calculation method of the cumulative difference in amplitude is: ,in, is the cumulative difference in amplitude, for The grid amplitude at the moment, for Inverter amplitude at the moment.

[0041] The cumulative amplitude difference refers to the cumulative difference between the amplitude of the inverter output voltage and the amplitude of the grid voltage. Amplitude differences are typically caused by system load variations or inaccurate inverter output adjustment. Ideally, the inverter output voltage amplitude should match the grid voltage amplitude to ensure reactive power balance and proper system operation.

[0042] The Precision Coordination Score provides a quantitative metric to clearly assess the synchronization and coordination between the inverter and the grid. A high score indicates stable system operation, smooth interaction between the inverter and the grid, and efficient energy transmission. A low score indicates that the system may require tuning or maintenance.

[0043] In this embodiment, the method for scoring accurate coordination is: ,in, Scoring for precise coordination, They are the weights of phase deviation, frequency tracking error, and amplitude accumulation difference respectively.

[0044] The Precision Coordination Score is a comprehensive assessment of key parameters such as leading or lagging phase deviation, frequency tracking error, and cumulative amplitude difference. It aims to quantify the effectiveness of the collaborative operation between the PV power plant and the grid. These parameters reflect the synchronization and coordination between the PV power plant inverter and the grid during operation, as well as the inverter's timely and accurate response to grid frequency and voltage fluctuations.

[0045] Step 4: Based on the voltage distribution in the grid data matrix at each time interval before and after the PV power station is connected to the grid, calculate the oscillation coefficient of the grid after grid connection. Calculate the response coefficient of the inverter based on the adjustment parameters of the inverter after grid connection. Evaluate the impact coefficient during closing based on the oscillation coefficient and response coefficient.

[0046] In this embodiment, the calculation method of the oscillation coefficient of the power grid after the grid connection is: Taking the voltage distribution before grid connection as the standard voltage, calculate the deviation of the standard voltage at each time interval. Calculate the oscillation coefficient of the grid by analyzing the continuous deviation of each area: ,in, is the oscillation coefficient of the power grid, is the standard voltage matrix, for The voltage matrix at each moment is: is the deviation matrix from the standard voltage, is the difference of the voltage elements in the deviation difference matrix, is the number of consecutive deviations from the differential voltage, is the number of sub-regions within the equipotential line, The first sub-areas.

[0047] The oscillation coefficient measures the degree of oscillation or fluctuation in the power grid caused by the integration of a PV power plant. After integration, the PV power plant converts DC power into AC power via an inverter and injects it into the grid. Due to the different dynamic responses of the grid and the PV power plant, this can cause fluctuations in grid voltage and frequency, leading to oscillations. The oscillation coefficient reflects the intensity and duration of these fluctuations. By calculating the oscillation coefficient, we can quantify the grid stability during the integration process and understand the impact of the PV power plant on the grid. This allows grid operators to make necessary adjustments to the integration process based on the oscillation coefficient to avoid system instability.

[0048] The inverter adjustment parameters include the inverter output voltage after grid connection, the inverter grid-connected stable output voltage, the time when the inverter starts adjusting the voltage, the time when the inverter adjusted voltage stabilizes, and the inverter target voltage; The formula for calculating the response coefficient of the inverter is: ,in, is the response coefficient of the inverter, is the inverter output voltage after grid connection, To stabilize the output voltage of the inverter when connected to the grid, is the inverter target voltage, The moment when the inverter starts to adjust the voltage. Adjust the voltage stabilization time for the inverter.

[0049] The response factor measures how quickly and effectively an inverter adjusts its output to adapt to grid changes during the grid connection process. Inverter adjustment parameters (such as output power and phase angle) have a significant impact on grid stability and power quality. The response factor indicates the inverter's ability to respond to grid fluctuations and is typically calculated based on the inverter's control strategy and real-time response capabilities. By calculating the response factor, we can assess the inverter's ability to adjust to grid changes, ensuring a quick and effective response to grid frequency or voltage fluctuations, thereby minimizing the impact of grid connection.

[0050] In this embodiment, the calculation formula for evaluating the influence coefficient during closing based on the oscillation coefficient and the response coefficient is: ,in, is the influence coefficient, Adjust the base for the oscillation coefficient sensitivity, Adjust the base number for the oscillation coefficient limit.

[0051] Step 5: Obtain the initial grid parameters when the PV power station is not connected to the grid as a reference for weight distribution, and evaluate the comprehensive operating performance of the PV power station when it is connected to the grid based on the regional dispatch score, precise coordination score, and switching comprehensive score.

[0052] In this embodiment, the initial grid parameters include the power demand of the power dispatch area, the voltage, current, voltage fluctuation amplitude, harmonic distortion rate, and voltage frequency deviation of each sub-area; The method for obtaining the initial grid parameters of the photovoltaic power station before grid connection as a reference for weight distribution is: The dynamic weight of the regional dispatch score is calculated based on the power demand, voltage, and current of the power dispatch area: ,in, Dynamic weights for scoring regional dispatches, The limiting coefficient for the dynamic weight of the regional dispatch score, is the power of the sub-region, is the average value of the electricity in the sub-area, is the balance of power distribution, is the voltage of the sub-region, is the current in the sub-region, For the The amount of electricity in each sub-region, They are the first Row, No. List.

[0053] The dynamic weight of the regional dispatch score is calculated based on parameters such as power demand, voltage, and current within the power grid. This factor takes into account the load demand, grid stability, and dispatch capabilities of the regional power grid under existing grid conditions. If the regional power grid load is high and fluctuates frequently, dispatching becomes more difficult, making regional coordination more challenging initially.

[0054] The dynamic correction weight of the precise coordination score is calculated based on the fluctuation amplitude of current and voltage, harmonic distortion rate, and frequency deviation of voltage: ,in, Dynamically correct weights for precise coordination scoring, The limiting coefficient for the dynamic correction weight of the precise coordination score, is the voltage fluctuation amplitude in the area of power dispatch, is the standard voltage amplitude, is the harmonic distortion rate, The frequency deviation of the voltage in the area of power dispatch, The standard frequency of the voltage in the area where electricity is dispatched.

[0055] The dynamic weighting of the precision coordination score is calculated based on factors such as current and voltage fluctuation amplitudes, harmonic distortion, and voltage-frequency deviation. It reflects the impact of grid scheduling on the post-grid connection of PV power plants and the accuracy requirements for grid coordination. Factors such as large voltage fluctuations and unstable current fluctuations indicate that more precise coordination is required to ensure stable grid operation.

[0056] The setting of dynamic weights can flexibly adjust the weights of regional dispatch and precise coordination scores according to the actual operating status of the power grid. For example, in areas with heavy power grid loads and large voltage fluctuations, the initial difficulty of regional coordination is higher. At this time, the dynamic weight will increase the weight of the regional dispatch score, making this area occupy a larger proportion in the comprehensive score. Similarly, when the voltage fluctuation is large or the harmonic distortion is severe, the weight of the precise coordination score will be dynamically adjusted to ensure that a higher weight is allocated to the precise coordination part, reflecting the higher demand for precise coordination during the operation of the region. By determining the dynamic weight based on the initial difficulty of regional coordination and the initial difficulty of precise coordination, this solution can make a more scientific and detailed evaluation of the dispatch and coordination difficulty of different regions. This not only accurately reflects the operating status of each regional power grid, but also provides more actionable dispatch suggestions, so that the grid-connected operation of the power grid and photovoltaic power station is more in line with actual needs.

[0057] In this embodiment, the calculation formula for evaluating the comprehensive operation performance based on the regional scheduling score, the precise coordination score, and the switching comprehensive score is: ,in, is the running comprehensive value, Score the regional dispatch, Scoring for precise coordination, is the influence coefficient, They are the regional scheduling score, precise coordination score, and the weight of the impact coefficient; when When the system is in good condition, in, This parameter is the threshold for judging the system operation status.

[0058] The above formulas are all dimensionless and numerical calculations. The formulas are obtained by collecting a large amount of data and performing software simulation to obtain the most recent real situation. The preset parameters in the formulas are set by technicians in this field according to actual conditions.

[0059] The above embodiments can be implemented in whole or in part by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software depends on the specific application and design constraints of the technical solution.

[0060] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, and may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment as needed.

[0061] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

Claims

1. A method for evaluating the comprehensive performance of grid-connected photovoltaic power stations, characterized in that: The specific steps include: Step 1: Divide the area where the PV power station dispatches power to the grid into multiple sub-areas based on the distribution of the grid. Obtain the voltage and current of the grid in each sub-area, stamp them with timestamps to form time series data, and sample them at the same time interval. The voltage and current sampled in each sub-area correspond to a matrix element, forming a grid data matrix that is mapped one-to-one with the location of the sub-area. Step 2: Obtain the grid data matrix after the PV power station is connected to the grid, determine the real-time dispatch area based on the voltage distribution, calculate the regional dispatch coefficient based on the real-time dispatch area, calculate the dispatch power ratio based on the grid voltage and current, determine the grid voltage fluctuation stability coefficient by analyzing the continuous grid data matrix, and score the regional dispatch of the power dispatch area; Step 3: Obtain real-time voltage data from the grid and inverter after the PV power station is connected to the grid, filter it, and calculate the leading or lagging phase deviation, frequency tracking error, and amplitude accumulation difference based on the voltage data at the same consecutive time intervals, and score the precise coordination. Step 4: Based on the voltage distribution in the grid data matrix at each time interval before and after the PV power station is connected to the grid, calculate the oscillation coefficient of the grid after grid connection. Calculate the inverter response coefficient based on the inverter adjustment parameters after grid connection. Evaluate the impact coefficient during closing based on the oscillation coefficient and response coefficient. Step 5: Obtain the initial grid parameters when the PV power station is not connected to the grid as a reference for weight distribution, and evaluate the comprehensive operating performance of the PV power station when it is connected to the grid based on the regional dispatch score, precise coordination score, and switching comprehensive score.

2. A photovoltaic power station grid-connected operation comprehensive performance evaluation method according to claim 1, characterized in that; The specific method for determining the range of the real-time dispatch area based on the voltage distribution and calculating the regional dispatch coefficient based on the real-time dispatch area is as follows: The lowest voltage value closest to the photovoltaic power station grid connection point in the upstream direction of the current transmission direction of the power grid is the equipotential value, and all equipotential values are connected with the photovoltaic power station grid connection point as the center to form an equipotential line. The area within the equipotential line is the dispatching area range. The specific calculation formula is: ,in, is the regional scheduling coefficient, Standard power supply area of PV power station, The first The area of the sub-region, is the number of sub-regions within the equipotential line; The calculation method for the dispatch power ratio is: ,in, is the dispatching power ratio, are the voltage and current output by the photovoltaic power station, For the dispatch area Input voltage and input current, is the total circuit quantity of input voltage and input current, For the dispatch area Output voltage and output current, is the total number of circuits with output voltage and output current; The method for determining the grid voltage fluctuation stability coefficient by analyzing the continuous grid data matrix is: The voltage change difference is calculated for the grid data matrix of adjacent time intervals within the dispatching area. Based on the continuous voltage change of each sub-area, the voltage fluctuation stability coefficient of the entire area is calculated: ,in, is the voltage fluctuation stability coefficient, The number of consecutively sampled data, For sub-region The voltage change at each moment, is the mean value of continuous voltage change, is the number of sub-regions within the equipotential line, The first sub-areas.

3. A photovoltaic power station grid-connected operation comprehensive performance evaluation method according to claim 2, characterized in that: The method for scoring regional dispatch of power dispatch areas is as follows: ,in, Score the regional dispatch, are the weights of regional dispatch coefficient and voltage fluctuation stability coefficient respectively.

4. A photovoltaic power station grid-connected operation comprehensive performance evaluation method according to claim 3, characterized in that: The voltage data includes phase, frequency and amplitude; The calculation method of the phase deviation is: ,in, is the phase accumulator, for The grid phase at the moment, for Inverter phase at the moment, is the number of continuous voltage data obtained, To obtain the Voltage data; The calculation formula of the frequency tracking error is: ,in, is the frequency tracking error, for The grid frequency at the moment, for Inverter frequency at all times; The calculation method of the cumulative difference in amplitude is: ,in, is the cumulative difference in amplitude, for The grid amplitude at the moment, for The inverter amplitude at that moment.

5. A photovoltaic power station grid-connected operation comprehensive performance evaluation method according to claim 4, characterized in that: The method for scoring precise coordination is: ,in, Scoring for precise coordination, They are the weights of phase deviation, frequency tracking error, and amplitude accumulation difference respectively.

6. The method for evaluating the comprehensive performance of grid-connected photovoltaic power stations according to claim 1, wherein: The calculation method of the oscillation coefficient of the power grid after the grid connection is: Taking the voltage distribution before grid connection as the standard voltage, calculate the deviation of the standard voltage at each time interval. Calculate the oscillation coefficient of the grid by analyzing the continuous deviation of each area: ,in, is the oscillation coefficient of the power grid, is the standard voltage matrix, for The voltage matrix at each moment is: is the deviation matrix from the standard voltage, is the difference of the voltage elements in the deviation difference matrix, is the number of consecutive deviations from the differential voltage, is the number of sub-regions within the equipotential line, The first sub-regions; The formula for calculating the response coefficient of the inverter is: ,in, is the response coefficient of the inverter, is the inverter output voltage after grid connection, To stabilize the output voltage of the inverter when connected to the grid, is the inverter target voltage, The moment when the inverter starts to adjust the voltage. Adjust the voltage stabilization time for the inverter.

7. A photovoltaic power station grid-connected operation comprehensive performance evaluation method according to claim 6, characterized in that: The calculation formula for evaluating the influence coefficient during closing based on the oscillation coefficient and the response coefficient is: ,in, is the influence coefficient, Adjust the base for the oscillation coefficient sensitivity, Adjust the base number for the oscillation coefficient limit.

8. The method for evaluating the comprehensive performance of grid-connected photovoltaic power stations according to claim 1, wherein: The initial grid parameters include the power demand of the power dispatching area, the voltage, current, voltage fluctuation amplitude, harmonic distortion rate, and voltage frequency deviation of each sub-area; The method for obtaining the initial grid parameters when the photovoltaic power station is not connected to the grid as a reference for weight distribution is: The dynamic weight of the regional dispatch score is calculated based on the power demand, voltage, and current of the power dispatch area: ,in, Dynamic weights for scoring regional dispatches, The limiting coefficient for the dynamic weight of the regional dispatch score, is the power of the sub-region, is the average value of the electricity in the sub-area, is the balance of power distribution, is the voltage of the sub-region, is the current in the sub-region, For the The amount of electricity in each sub-region, They are the first Row, No. List; The dynamic correction weight of the precise coordination score is calculated based on the fluctuation amplitude of current and voltage, harmonic distortion rate, and frequency deviation of voltage: ,in, Dynamically correct weights for precise coordination scoring, The limiting coefficient for the dynamic correction weight of the precise coordination score, is the voltage fluctuation amplitude in the area of power dispatch, is the standard voltage amplitude, is the harmonic distortion rate, The frequency deviation of the voltage in the area of power dispatch, The standard frequency of the voltage in the area where electricity is dispatched.

9. A photovoltaic power station grid-connected operation comprehensive performance evaluation method according to claim 8, characterized in that: Based on the regional dispatch score, precise coordination score, and comprehensive switching score, the calculation formula for evaluating the comprehensive operating performance of the photovoltaic power station when it is connected to the grid is: ,in, is the running comprehensive value, Score the regional dispatch, Scoring for precise coordination, is the influence coefficient, They are the regional scheduling score, precise coordination score, and the weight of the impact coefficient; when When the system is in good condition, in, This parameter is the threshold for judging the system operation status.

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