A household-level baseline normalization photovoltaic multi-stage collaborative regulation method and system

Abstract

The application discloses a kind of household-level baseline normalization photovoltaic multistage collaborative regulation method and system, the method of the application includes control main station issues voltage autonomous regulation instruction;Area concentrator constructs load normalization line voltage drop baseline model to obtain the curve fitting parameter of photovoltaic user, according to first monitoring period, collects power grid data, according to the curve fitting parameter of each photovoltaic user, the load normalization line voltage drop baseline corresponding to each photovoltaic user is calculated, and the voltage of photovoltaic user who exceeds limit is screened out and issues voltage regulation authorization instruction;The new energy electric energy metering monitoring terminal (abbreviation: new energy terminal) corresponding to the screened photovoltaic user is according to second monitoring period, and local grid connection point voltage is collected, and local autonomy is carried out in combination with the local grid connection point voltage obtained by acquisition.The application aims at accurately stripping load change influence, according to user independent identification photovoltaic voltage contribution, realize fine power regulation and protection flexible linkage distributed photovoltaic voltage autonomous regulation.

Description

Technical Field

[0001] This invention relates to the field of voltage control technology for distributed photovoltaic power generation and low-voltage distribution networks, specifically to a photovoltaic multi-level coordinated control method and system with household-level baseline normalization. Background Technology

[0002] The problem of voltage exceeding limits in low-voltage distribution networks caused by a high proportion of distributed photovoltaic grid connection is becoming increasingly serious. Existing voltage self-regulation methods have fundamental flaws in identifying the causes of voltage exceeding limits: they typically employ a simple threshold comparison strategy, i.e., when the voltage at the grid connection point... Power regulation is initiated when the voltage exceeds a set threshold, without distinguishing whether the voltage exceedance is caused by the photovoltaic power generation itself or by grid-side factors (such as high upstream grid voltage, transformer tap position, heavy load unloading, etc.). More importantly, existing technology, if the transformer output voltage... As a reference benchmark, an attempt was made to compare the grid connection point voltage. With transformer output voltage Using the difference between the photovoltaic (PV) grid connection voltage and the transformer output voltage to determine the PV contribution has serious physical model flaws. The difference between the PV grid connection voltage and the transformer output voltage consists of two parts: the first part is the line voltage drop (determined by line impedance, load current, and transformer distance), and the second part is the voltage rise caused by PV output. The line voltage drop varies significantly under different load levels, with a large line voltage drop under heavy load and a small line voltage drop under light load. Therefore, the baseline of the line voltage drop measured during the zero-output period at night is completely different from the line voltage drop during the high-load period during the day. Directly subtracting the measured value during the day from the fixed baseline will miscalculate the load change as a PV contribution, leading to misjudgment. In addition, the existing technology uses a sequential upgrade strategy when switching multi-level thresholds, resulting in a slow response; the power regulation uses a fixed step size, which does not consider the current output level of the inverter, leading to over-adjustment at low output and under-adjustment at high output; protection actions and flexible regulation are executed separately, resulting in unnecessary grid disconnection; and the recovery strategy uses a fixed threshold, which does not consider the real-time status of grid voltage deviation. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a photovoltaic multi-level coordinated control method and system with household-level baseline normalization, which addresses the above-mentioned problems in the prior art. This invention aims to accurately isolate the impact of load changes, identify the photovoltaic voltage contribution independently by each user, and realize distributed photovoltaic voltage autonomous control with fine power regulation and flexible protection linkage.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for multi-level coordinated control of photovoltaic systems with household-level baseline normalization includes the following steps: S101, the control station sends a voltage autonomous control command to the concentrator of the target area; S102, after receiving the voltage autonomous control command, the concentrator of the target distribution area constructs a load normalized line voltage drop baseline model by performing curve fitting on the measured voltage drop and the total active load power of the distribution area for each photovoltaic user, so as to obtain the curve fitting parameters of each photovoltaic user. S103, the concentrator of the target area collects grid data according to the first monitoring cycle, calculates the corresponding load normalized line voltage drop baseline based on the curve fitting parameters of each photovoltaic user, screens out photovoltaic users with voltage exceeding the limit based on the load normalized line voltage drop baseline, and issues voltage regulation authorization instructions to the new energy power metering and monitoring terminal corresponding to the screened photovoltaic users. S104. After receiving the voltage regulation authorization instruction, the new energy power metering and monitoring terminal corresponding to the selected photovoltaic user collects the local grid connection point voltage according to the second monitoring cycle, and performs local self-governance in combination with the collected local grid connection point voltage.

[0005] Optionally, in step S102, when constructing a load-normalized line voltage drop baseline model for each photovoltaic user based on curve fitting of the measured voltage drop and the total active power load of the distribution area during a specified time period, the functional expression of the constructed load-normalized line voltage drop baseline model is: ; in, Total active load power of the transformer area Next Normalized line voltage drop baseline for each photovoltaic user's load and The first The slope and intercept of the curve fitting parameters for each photovoltaic user.

[0006] Optionally, in step S102, when constructing a load-normalized line voltage drop baseline model for each photovoltaic user based on curve fitting of the measured voltage drop and the total active power load of the distribution area during a specified time period, the first... The function expressions for calculating the slope and intercept in the curve fitting parameters for a photovoltaic user are as follows: ; ; in, The number of samples used to fit the sample set. To fit the total active load power of the substation area for the j-th sample in the sample set, For the fitted sample set, the first... The measured voltage drop of the j-th sample of a photovoltaic user For the first The slope of the curve fitting parameters for each photovoltaic user To fit the sum of the total active load power of the transformer substations in the sample set, This is the sum of the measured pressure drops of all samples in the fitted sample set. For the first The intercept of the curve fitting parameters for each photovoltaic user.

[0007] Optionally, in step S102, when constructing a load-normalized line voltage drop baseline model for each photovoltaic user based on curve fitting of the measured voltage drop and the total active power load of the distribution area during a specified time period, the specified time period is the near-zero output period, and the near-zero output period is the photovoltaic active power output. Below the near-zero output threshold The near-zero output threshold during the specified time period. These are parameters in the voltage autonomous control command.

[0008] Optionally, step S103 includes: S201, the concentrator of the target distribution area collects power grid data according to the first monitoring cycle. The power grid data includes the transformer outlet voltage and the total active load power of the distribution area. S202, calculate the corresponding load-normalized line voltage drop baseline based on the curve fitting parameters of each photovoltaic user; calculate the deviation between the measured voltage drop of each photovoltaic user and the load-normalized line voltage drop baseline based on the load-normalized line voltage drop baseline: ; in, For the first The deviation between the measured voltage drop of a photovoltaic user and the expected baseline. This is the transformer output voltage. For the first The grid connection voltage of each photovoltaic user Total active load power of the transformer area Next Normalized line voltage drop baseline for individual photovoltaic users' loads; S203, calculate the unit output voltage gain for each photovoltaic user in the target area: ; in, For the first The unit output voltage gain of a photovoltaic user for The absolute value, For the first The active power output of photovoltaic users ( ≠0); S204, filter out units with voltage gain per unit output greater than a preset threshold. Photovoltaic users are considered photovoltaic users whose voltage exceeds the limit; S205, a voltage regulation authorization instruction is issued to the new energy power metering and monitoring terminal corresponding to the selected photovoltaic users. The voltage regulation authorization instruction carries a subset of regulation parameters. ={ , , , , , ~ , When the enable flag of the main station control is disabled or the control period has expired, the distribution area concentrator sends a voltage control authorization command with the enable flag disabled to the authorized new energy power metering and monitoring terminal. After receiving the voltage control authorization command with the enable flag disabled, the new energy power metering and monitoring terminal exits the local autonomous state and gradually restores active power output according to the preset recovery step size.

[0009] Optionally, the local autonomy in step S104, which combines the acquired local grid connection point voltage, includes: [The text abruptly ends here, so the translation stops as well.] The voltage exceeds the lowest-level over-limit threshold voltage carried in the voltage regulation authorization command. Flexible power regulation is performed, which includes first invoking the inverter to perform reactive power regulation according to the following formula: ; in, The adjusted reactive power. This represents the current reactive power. The sign for voltage over-limit is +1 for overvoltage and -1 for undervoltage. 1; To obtain the minimum value, To adjust the step size as a percentage, The rated capacity of the inverter. This is the upper limit of reactive power; if the reactive power regulation capacity is exhausted and the collected local grid connection point voltage is... It is still greater than the lowest level of over-limit threshold voltage carried in the voltage regulation authorization instruction. Then, the inverter is invoked to perform active power reduction according to the following formula: ; in, The reduced active power, The current active power, This is the upper limit of active power.

[0010] Optionally, when performing local autonomy in step S104 by combining the acquired local grid connection point voltage, it also includes using the acquired local grid connection point voltage... Combined with the four-level over-limit threshold voltage carried in the voltage regulation authorization instruction ~ Determine the current control level Level 4 over-limit threshold voltage ~ satisfy ; If the local grid connection point voltage satisfy Then the control level =1; If the local grid connection point voltage satisfy Then the control level It is 2; If the local grid connection point voltage satisfy Then the control level It is 3; If the local grid connection point voltage satisfy Then the control level It is 4; The local grid connection point voltage obtained from the data acquisition The voltage exceeds the lowest-level over-limit threshold voltage carried in the voltage regulation authorization command. When performing flexible power regulation, including at the control level Flexible power adjustment is performed when the power is between 1 and 3.

[0011] Optionally, when performing local autonomy in step S104 by combining the acquired local grid connection point voltage, it further includes ensuring that the acquired local grid connection point voltage meets the following conditions: And the duration exceeds the preset time. The countdown to the circuit breaker tripping begins. During the countdown, if the local grid connection point voltage is collected... Falling back to voltage The following steps cancel the tripping operation, where the voltage... This refers to the highest-level over-limit threshold voltage carried in the voltage regulation authorization command. This refers to the delay parameter carried in the voltage regulation authorization command.

[0012] Optionally, when performing local autonomy in step S104 by combining the acquired local grid connection point voltage, it also includes using the acquired local grid connection point voltage... Meets recovery conditions And the duration exceeds the time limit. A gradual recovery strategy is implemented, in which... The recovery voltage carried in the voltage regulation authorization command, time The recovery time carried in the voltage regulation authorization command. For dynamic voltage offset, and have: = - ; in, This is the transformer output voltage. Rated voltage; The gradual recovery strategy includes invoking the inverter to perform active power recovery according to the following formula: ; in, This refers to the increase in active power during a single active power recovery. To obtain the minimum value, For percentage recovery step size, Rated active power, This is the upper limit of active power.

[0013] The present invention also provides a photovoltaic multi-level coordinated control system with household-level baseline normalization, including a microprocessor and a memory interconnected, wherein the microprocessor is programmed or configured to execute the photovoltaic multi-level coordinated control method with household-level baseline normalization.

[0014] Compared with the prior art, the present invention can mainly achieve the following beneficial effects: The present invention can establish a load normalized line voltage drop baseline model for each photovoltaic user, accurately isolate the impact of load changes on line voltage drop, accurately determine whether voltage over-limit is caused by the photovoltaic power generation of the user, avoid making incorrect power adjustment for voltage over-limit caused by grid factors, and realize multi-level coordinated fine regulation and flexible protection linkage, accurately isolate the impact of load changes, independently identify the photovoltaic voltage contribution of each user, and realize distributed photovoltaic voltage autonomous regulation with fine power adjustment and flexible protection linkage. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the basic process of the method in an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the system structure in an embodiment of the present invention.

[0017] Figure 3 This is a flowchart illustrating step S103 in an embodiment of the present invention.

[0018] Figure 4 This is a timing diagram illustrating the parallel linkage of rigid protection and flexible regulation in the tripping operation of an embodiment of the present invention.

[0019] Figure 5 This is a timing diagram illustrating the parallel linkage between rigid protection and flexible adjustment to cancel the tripping in an embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings in the embodiments of the present invention.

[0021] like Figure 1 and Figure 2 As shown, the photovoltaic multi-level coordinated control method with household-level baseline normalization in this embodiment includes the following steps: S101, the control station sends a voltage autonomous control command to the concentrator of the target area; S102, after receiving the voltage autonomous control command, the concentrator of the target distribution area constructs a load normalized line voltage drop baseline model by performing curve fitting on the measured voltage drop and the total active load power of the distribution area for each photovoltaic user, so as to obtain the curve fitting parameters of each photovoltaic user. S103, the concentrator of the target area collects grid data according to the first monitoring cycle, calculates the corresponding load normalized line voltage drop baseline based on the curve fitting parameters of each photovoltaic user, screens out photovoltaic users with voltage exceeding the limit based on the load normalized line voltage drop baseline, and issues voltage regulation authorization instructions to the new energy power metering and monitoring terminal corresponding to the screened photovoltaic users. S104. After receiving the voltage regulation authorization instruction, the new energy power metering and monitoring terminal corresponding to the selected photovoltaic user collects the local grid connection point voltage according to the second monitoring cycle, and performs local self-governance in combination with the collected local grid connection point voltage.

[0022] In step S101 of this embodiment, when the control master station sends a voltage autonomous control command to the concentrator of the target area, the voltage autonomous control command includes a control enable flag, a control period, and a control parameter set. θ ={ , , , , , ~ , , },in < < < This is the fourth-level threshold. To restore the threshold, ~ For delays at all levels, The threshold for judging voltage gain per unit output (unit: V / kW). The near-zero output threshold is set (usually 3% of the rated capacity); the control master station is responsible for the unified distribution of global strategies and monitoring of operating status, but does not participate in real-time closed-loop control.

[0023] In step S102, after receiving the voltage autonomous control command, the concentrator in the target distribution area collects data according to the baseline acquisition cycle. The following data were collected simultaneously: (a) Transformer outlet voltage Voltage at the grid connection point of each photovoltaic user Calculate the measured pressure drop during this period. = (Actual voltage drop is generally positive at night and reverses to negative during the day when photovoltaic power generation is high, indicating an increase in voltage); (b) Total active load power of the distribution area The data, sourced from the district meter or the local metering unit at the terminal, is used to characterize the current line load level; for the first... i Each photovoltaic user will N Using historical data (measured voltage drop, total active load power of the transformer area) as a sample, it can be expressed as: {( , )}| =1~ ; In step S102 of this embodiment, when constructing the load-normalized line voltage drop baseline model for each photovoltaic user based on the measured voltage drop and the total active power of the distribution area during a specified time period, this includes independently fitting and establishing the load-normalized line voltage drop baseline model for that user using the least squares method (selecting the optimal fitting strategy that minimizes the sum of squared residuals). The functional expression of the constructed load-normalized line voltage drop baseline model is as follows: ; in, Total active load power of the transformer area Next Normalized line voltage drop baseline for each photovoltaic user's load and The first The slope and intercept (linear model) of the curve fitting parameters for a photovoltaic user are used. The slope reflects the coupling coefficient between the user's line equivalent impedance and the distance from the grid connection point to the transformer, while the intercept reflects the combined constant of the user's measurement system inherent bias and fixed line loss.

[0024] In step S102 of this embodiment, when constructing a load-normalized line voltage drop baseline model for photovoltaic users based on curve fitting of the measured voltage drop and the total active power of the distribution area during a specified time period, the first... The function expressions for calculating the slope and intercept in the curve fitting parameters for a photovoltaic user are as follows: ; ; in, The number of samples used to fit the sample set. To fit the total active load power of the substation area for the j-th sample in the sample set, For the fitted sample set, the first... The measured voltage drop of the j-th sample of a photovoltaic user For the first The slope of the curve fitting parameters for each photovoltaic user To fit the sum of the total active load power of the transformer substations in the sample set, This is the sum of the measured pressure drops of all samples in the fitted sample set. For the first The intercept and slope in the curve fitting parameters for each photovoltaic user. The physical meaning is: the change in voltage difference between the user's grid connection point and the transformer outlet caused by a change in the load power of a unit distribution area. It automatically includes topology parameters that cannot be directly measured, such as the user's line impedance, cable length, and wiring method. The slope for different users... Significant differences in values: Slope of users near the transformer Small, remote user slope Large. The concentrator in the distribution area independently stores a set of data for each photovoltaic user in its local memory. , The parameters are used to form an independent baseline model library at the household level. Considering seasonal variations in line temperature (higher conductor temperature and increased resistance in summer, and vice versa in winter), the transformer concentrator automatically updates the baseline model parameters monthly: 40 new samples are collected during periods of near-zero output, merged with historical samples (a total of 80 samples), and least-squares fitting is re-performed to update the parameters. , If new With the old If the deviation exceeds 10%, a parameter anomaly alarm is triggered, indicating possible line aging or poor contact. The main station collects data from all transformer substations within its jurisdiction. , Statistical distribution reveals typical characteristics of a certain region. The average value is approximately 0.15V / kW (corresponding to a line distance of 200-300m). The main station adjusts its load based on seasonal high-load statistics during the summer and winter high-load seasons. The voltage level has been increased from 0.5V / kW to 0.6V / kW, making the judgment more stringent; this will be applied during the light-load seasons of spring and autumn. The voltage was lowered to 0.4V / kW to avoid misjudgment due to small voltage drop under light load. The dynamic adjustment is achieved by periodically issuing the control parameter set θ of S101.

[0025] In this embodiment, in step S102, when constructing a load-normalized line voltage drop baseline model for each photovoltaic user based on curve fitting of the measured voltage drop and the total active power load of the distribution area during a specified time period, the specified time period is the near-zero output period, and the near-zero output period is the photovoltaic active power output. Below the near-zero output threshold The near-zero output threshold during the specified time period. These are parameters in the voltage autonomous control command. The near-zero output threshold is also relevant. When the value is 3% of the rated capacity, the near-zero output periods include nighttime, cloudy days, early morning, and evening.

[0026] Suppose a 380V low-voltage distribution area has 3 distributed photovoltaic (PV) users. User 1 is 50m from the transformer (near end), User 2 is 200m from the transformer (mid-end), and User 3 is 400m from the transformer (far end). The transformer has a rated capacity of 200kVA, and the wiring uses JKLYJ-1kV-70 conductor with a resistivity of approximately 0.45Ω / km. The inverter rated capacities are: 20kW for User 1, 30kW for User 2, and 50kW for User 3. This is a 380V / 220V three-phase four-wire low-voltage distribution area, with a rated voltage of 220V at the user grid connection point. The distribution area concentrator collects data during the near-zero output period (22:00 to 06:00 the next day) for 5 consecutive days, recording one set of data per hour, accumulating approximately 40 sets of samples per user. Taking User 2 (mid-end, 30kW) as an example, some sample data is shown in Table 1.

[0027] Table 1: Sample Data Examples for Household 2

[0028] Least squares fitting was performed on 40 samples from household 2 to obtain the slope of household 2. It is 0.142 V / kW. The voltage is 3.41V. Similarly, by fitting, we obtain the slope of user 1. It is 0.045 V / kW. The voltage is 1.22V. The slope of user 3 is... It is 0.238V / kW. It is 4.85V. The concentrator in the distribution area will ( , ), ( , ), ( , These are stored separately in a household-level independent baseline model library.

[0029] After entering the normal operating period, the concentrator in the distribution area will operate according to the first monitoring cycle. Collect transformer output voltage Voltage at each photovoltaic user's grid connection point Each user's photovoltaic power output and the current total load power of the transformer area. For example, at 12:00 noon on a certain day, the operating data of the transformer area is as follows: =240V (Transformer output voltage is normally slightly high). =50kW (medium load), photovoltaic output of household 2 =28kW, grid connection point voltage of household 2 =248V.

[0030] The distribution concentrator scans all photovoltaic (PV) users, calculates the corresponding load-normalized line voltage drop baseline based on the curve fitting parameters of each PV user, and then filters out PV users with voltage exceeding limits based on the load-normalized line voltage drop baseline. It then issues voltage regulation authorization commands to the corresponding new energy metering and monitoring terminals of these filtered PV users. For example... Figure 3 As shown, step S103 in this embodiment includes: S201, the concentrator of the target distribution area collects power grid data according to the first monitoring cycle. The power grid data includes the transformer outlet voltage and the total active load power of the distribution area. S202, calculate the corresponding load normalized line voltage drop baseline based on the curve fitting parameters of each photovoltaic user, i.e., substitute the current total active power of the distribution area. The current total active load power of the transformer area is obtained. The corresponding load-normalized line voltage drop baseline accurately reflects the line voltage drop that should occur if the user's photovoltaic system is not generating power under the current load level of the distribution area. The deviation between the measured voltage drop of each photovoltaic user and the load-normalized line voltage drop baseline is calculated based on this baseline. ; in, For the first The deviation between the measured voltage drop of a photovoltaic user and the expected baseline. This is the transformer output voltage. For the first The grid connection voltage of each photovoltaic user Total active load power of the transformer area Next Normalized line voltage drop baseline for individual photovoltaic users' loads; The physical meaning is: after removing the normal line voltage drop under the current load level, This indicates that photovoltaics caused a rise in net voltage. The magnitude of the increase; S203, calculate the unit output voltage gain for each photovoltaic user in the target area: ; in, For the first Voltage gain per unit output of a photovoltaic user (unit: V / kW). for The absolute value, For the first Photovoltaic active power output of individual photovoltaic users; voltage gain per unit output It represents how many volts the grid connection point voltage rises relative to the grid-side voltage benchmark for every 1kW of active power generated by the user. It eliminates the line voltage drop fluctuations caused by changes in the load level of the distribution area, while retaining the net voltage rise characteristics caused by unit photovoltaic output. This makes the determination of the cause of exceeding the limit unaffected by real-time changes in the load level and has cross-user comparability. S204, filter out units with voltage gain per unit output greater than a preset threshold. Photovoltaic users are considered photovoltaic users whose voltage exceeds the limit; specifically, in this embodiment, the transformer concentrator will compare it with a preset threshold: if... > The system determined that the user's voltage exceedance was primarily caused by their photovoltaic power generation. A voltage regulation authorization command was then issued to the user's new energy power metering and monitoring terminal. Upon receiving the authorization, the terminal collected the local grid-connected voltage according to the second monitoring cycle and adjusted the voltage regulation according to the instructions provided in the voltage regulation authorization command. Real-time determination of the current control level ;like ≤ If the voltage over-limit of the user is determined to be mainly caused by grid-side factors, power regulation for the user will not be initiated, thereby avoiding the erroneous reduction of the user's power generation revenue when the voltage over-limit is caused by grid factors. S205, a voltage regulation authorization instruction is issued to the new energy power metering and monitoring terminal corresponding to the selected photovoltaic users. The voltage regulation authorization instruction carries a subset of regulation parameters. ={ , , , , , ~ , When the enable flag of the main station control is disabled or the control period has expired, the distribution area concentrator sends a voltage control authorization command with the enable flag disabled to the authorized new energy power metering and monitoring terminal. After receiving the voltage control authorization command with the enable flag disabled, the new energy power metering and monitoring terminal exits the local autonomous state and gradually restores active power output according to the preset recovery step size.

[0031] Taking the operational data of household 2 at 12:00 as an example, the district concentrator reads the current... =50kW, query parameters for user 2 ( =0.142, =3.41), calculate the expected baseline under the current load conditions: =0.142×50+3.41=10.51V; This expected baseline accurately reflects that, under a 50kW load level, the line voltage drop should be approximately 10.51V if Household 2's solar panels are not operating. The measured deviation is then calculated: Δ =( ) =(240-248)-10.51=-8-10.51=-18.51V; =| 18.51 / 28 = 0.661V / kW (0.5V / kW); The concentrator in the distribution area determined that the voltage of user 2 exceeded the limit by level one. =248V> =243V), and issues a voltage regulation authorization command to User 2 terminal; the terminal samples and confirms. lie in( , The interval is then determined. =1, activate flexible power regulation.

[0032] The following will further illustrate this with examples from multiple scenarios: (1) Comparison scenario: Judgment of household 3 on the same day.

[0033] Assume the voltage at the grid connection point of Household 3 (remote end) =253V (reaching the second-level over-limit threshold) =253V), photovoltaic output =40kW. =0.238×50+4.85=16.75V; Δ =( ) =(240-253)-16.75=-13-16.75=-29.75V, photovoltaic power causes a net voltage increase of 29.75V.

[0034] =| 29.75| / 40=0.744V / kW> (0.5V / kW) was determined to be a voltage over-limit caused by photovoltaic power generation. The distribution area concentrator issued a voltage regulation authorization command to the household terminal 3. The terminal locally determined m=2 and started the dual-constraint nonlinear fine regulation with reactive power priority and active power backup.

[0035] (2) Comparison scenario: Household 2 voltage exceeds limit but < Power grid factors are the dominant factor.

[0036] For example, a certain period of time =243V (output voltage is too high). =20kW (light load), PV power output for 2 households =25kW, 2 households connected to the grid =248V.

[0037] =0.142×20+3.41=6.25V Δ =( ) =(243-248)-6.25=-5-6.25=-11.25V =| 11.25 / 25 = 0.450V / kW (0.5V / kW) The voltage exceedance was determined to be caused by grid-side factors. =243V is inherently high, which is the main reason. = The threshold for photovoltaic dominance has not been reached. The regional concentrators will not issue control commands to avoid unduly reducing users' power generation revenue.

[0038] (3) Comparison scenario: In extreme scenarios, the photovoltaic system of household 2 is fully loaded and frequently occurs.

[0039] =20kW (light load, small line voltage drop). =240V (export voltage is too high) =253V (reached) =253V secondary threshold). =30kW (full load).

[0040] Δ =( ) =(240-253)-6.25=-13-6.25=-19.25V =| 19.25 / 30 = 0.642V / kW (0.5V / kW) The voltage exceedance was clearly determined to be caused by photovoltaic power generation. The distribution concentrator then issued a voltage regulation authorization command to the second household terminal. =253V, the terminal locally determines m=2, the terminal starts the dual-constraint nonlinear fine adjustment of reactive power priority and active power backup, and controls the grid connection point voltage within a reasonable range.

[0041] In step S104 of this embodiment, after the new energy power metering and monitoring terminal receives the voltage regulation authorization command, it collects the local grid connection point voltage according to the second monitoring cycle and enters the local autonomous state; the second monitoring cycle is shorter than the first monitoring cycle to ensure that the local response is faster than the dispatching cycle of the distribution area concentrator; when the terminal does not receive the regulation authorization, even if the local voltage momentarily exceeds the limit, it will not start the power regulation to prevent false operation when the distribution area outlet voltage is too high.

[0042] In this embodiment, step S104, performing local autonomy by combining the acquired local grid connection point voltage, includes: [The text abruptly ends here, likely due to an incomplete sentence or a missing section.] The voltage exceeds the lowest-level over-limit threshold voltage carried in the voltage regulation authorization command. Flexible power regulation is performed in real time. This flexible power regulation adopts a dual-constraint nonlinear fine regulation of "reactive power priority and active power backup". Specifically, it includes first calling the inverter to perform reactive power regulation according to the following formula: ; in, The adjusted reactive power. This represents the current reactive power. The sign for voltage over-limit is +1 for overvoltage and -1 for undervoltage. 1; To obtain the minimum value, Adjust the step size as a percentage (the value can be chosen as needed, for example, 5%). The rated capacity of the inverter. This is the upper limit of reactive power; if the reactive power regulation capacity is exhausted and the collected local grid connection point voltage is... It is still greater than the lowest level of over-limit threshold voltage carried in the voltage regulation authorization instruction. Then, the inverter is invoked to perform active power reduction according to the following formula: ; in, The reduced active power, The current active power, This is the upper limit of active power, which can be set according to the inverter's hardware ratings. Among them, This constitutes a dual constraint: the percentage step size ensures that the adjustment amount adapts to the current output level (small step size for fine adjustment at low output, and large step size for fast response at high output), and an upper limit on active power. To prevent sudden voltage drops or current surges caused by excessive adjustments.

[0043] In step S104 of this embodiment, when performing local autonomy by combining the acquired local grid connection point voltage, it also includes using the acquired local grid connection point voltage... Combined with the four-level over-limit threshold voltage carried in the voltage regulation authorization instruction ~ Determine the current control level Level 4 over-limit threshold voltage ~ satisfy ; If the local grid connection point voltage satisfy Then the control level =1; If the local grid connection point voltage satisfy Then the control level It is 2; If the local grid connection point voltage satisfy Then the control level It is 3; If the local grid connection point voltage satisfy Then the control level It is 4; The local grid connection point voltage obtained from the data acquisition The voltage exceeds the lowest-level over-limit threshold voltage carried in the voltage regulation authorization command. When performing flexible power regulation, including at the control level Flexible power adjustment is performed when the power is between 1 and 3.

[0044] In this embodiment, step S104, when performing local autonomy based on the acquired local grid connection point voltage, also includes ensuring that the acquired local grid connection point voltage satisfies... And the duration exceeds the preset time. The countdown to the circuit breaker tripping begins. During the countdown, if the local grid connection point voltage is collected... Falling back to voltage The following steps cancel the tripping operation, where the voltage... This refers to the highest-level over-limit threshold voltage carried in the voltage regulation authorization command. This refers to the delay parameter carried in the voltage regulation authorization command. For example... Figure 4 As shown, in this embodiment, the preset time The countdown time is 2 seconds. During the 2-second countdown to the circuit breaker trip, if the local grid connection point voltage is collected... Not back to voltage The following will trigger the circuit breaker trip, and the terminal will enter islanding detection mode; if... Figure 5 As shown, in this embodiment, the preset time The countdown time is 2 seconds. During the 2-second countdown to the circuit breaker trip, if the collected local grid connection point voltage meets the following conditions... Falling back to voltage The following will cancel the tripping operation. At the same time, the terminal will simultaneously perform flexible power regulation during the countdown period, that is, adopt a dual-constraint nonlinear fine regulation of "reactive power priority and active power backup".

[0045] For example, after receiving the voltage regulation authorization command, the user 2 terminal collects local data. =253V, local determination m=2, enter control mode. Inverter rated capacity =30kVA, current active power output =30kW, reactive power currently =-2kvar (capacitive, some reactive power has already been generated). Reactive power priority stage: The terminal queries the inverter's current reactive power output. Calculate the reactive power regulation margin ,in The rated reactive power capacity of the inverter ( (Determined by inverter specifications). If If >0, perform reactive power regulation; if It is close Furthermore, the voltage still exceeds the limit, triggering a switch to active power reserve. Active power reserve stage: %=5%, the current output percentage step is 5%×30=1.5kW, the upper limit of active power. =3kW, take =1.5kW. Therefore 28.5kW, power reduced by 1.5kW. Monitoring will continue in the next cycle; if the voltage still exceeds the limit, the process will continue. (5%· , The step size is reduced until the voltage recovers or reaches the minimum output limit. Assuming the voltage continues to deteriorate... =286V (reached) =286V), the protection device starts a 2-second countdown to trip the circuit breaker. During the countdown, the terminal continues to monitor the photovoltaic voltage. If the voltage drops below 285V within 2 seconds, the protection will cancel the trip; otherwise, the trip will be executed.

[0046] In this embodiment, step S104, when performing local autonomy in conjunction with the acquired local grid connection point voltage, also includes... (The sentence is incomplete and requires further context to be fully translated.) Meets recovery conditions And the duration exceeds the time limit. A gradual recovery strategy is implemented, in which... The recovery voltage carried in the voltage regulation authorization command, time The recovery time carried in the voltage regulation authorization command. For dynamic voltage offset, and have: = - ; in, This is the transformer output voltage. This is the rated voltage; when the mains voltage is too high... The recovery threshold is raised synchronously to prevent premature recovery from exceeding the limit again; when the grid voltage is normal. Restored to the standard threshold .

[0047] The gradual recovery strategy includes invoking the inverter to perform active power recovery according to the following formula: ; in, This refers to the increase in active power during a single active power recovery. To obtain the minimum value, For percentage recovery step size, Rated active power, This represents the upper limit of active power. Percentage recovery step size. The value can be selected as needed, for example, a 3% percentage recovery step size. Value less than percentage adjustment step size This can prevent oscillations.

[0048] In summary, the photovoltaic multi-level coordinated control method with household-level baseline normalization in this embodiment includes: the control station issuing voltage autonomous control commands; the distribution area concentrator constructing a load-normalized line voltage drop baseline model to obtain curve fitting parameters for photovoltaic users; collecting grid data according to the first monitoring cycle; calculating the load-normalized line voltage drop baseline for each photovoltaic user based on the curve fitting parameters; filtering out photovoltaic users with voltage exceeding limits and issuing voltage control authorization commands; and the new energy metering and monitoring terminal corresponding to the selected photovoltaic users collecting the local grid connection point voltage according to the second monitoring cycle, and performing local autonomous control based on the collected local grid connection point voltage. This photovoltaic multi-level coordinated control method with household-level baseline normalization can establish load-normalized line voltage drop baseline models for each photovoltaic user, accurately isolate the impact of load changes on line voltage drop, accurately determine whether voltage exceeding limits are caused by the user's photovoltaic power generation, avoid incorrect power adjustment for voltage exceeding limits caused by grid factors, and simultaneously achieve multi-level coordinated fine control and flexible protection linkage, accurately isolate the impact of load changes, independently identify photovoltaic voltage contributions for each user, and achieve distributed photovoltaic voltage autonomous control with fine power adjustment and flexible protection linkage.

[0049] Furthermore, this embodiment also provides a photovoltaic multi-level coordinated control system with household-level baseline normalization, including a microprocessor and a memory interconnected, wherein the microprocessor is programmed or configured to execute the photovoltaic multi-level coordinated control method with household-level baseline normalization.

[0050] Those skilled in the art will understand that the technical solutions provided by this invention may take the form of a method, system, or computer program product. Therefore, this invention may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this invention may take the form of a computer program product embodied on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, produce an implementation of the flowchart... Figure 1 One or more processes and / or boxes Figure 1The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0051] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A photovoltaic multi-level coordinated control method with household-level baseline normalization, characterized in that, Includes the following steps: S101, the control station sends a voltage autonomous control command to the concentrator of the target area; S102, after receiving the voltage autonomous control command, the concentrator of the target distribution area constructs a load normalized line voltage drop baseline model by performing curve fitting on the measured voltage drop and the total active load power of the distribution area for each photovoltaic user, so as to obtain the curve fitting parameters of each photovoltaic user. S103, the concentrator of the target area collects grid data according to the first monitoring cycle, calculates the corresponding load normalized line voltage drop baseline based on the curve fitting parameters of each photovoltaic user, screens out photovoltaic users with voltage exceeding the limit based on the load normalized line voltage drop baseline, and issues voltage regulation authorization instructions to the new energy power metering and monitoring terminal corresponding to the screened photovoltaic users. S104. After receiving the voltage regulation authorization instruction, the new energy power metering and monitoring terminal corresponding to the selected photovoltaic user collects the local grid connection point voltage according to the second monitoring cycle, and performs local self-governance in combination with the collected local grid connection point voltage.

2. The photovoltaic multi-level coordinated control method with household-level baseline normalization according to claim 1, characterized in that, In step S102, when constructing a load-normalized line voltage drop baseline model for each photovoltaic user based on the measured voltage drop and the total active power load of the distribution area during a specified time period, the functional expression of the constructed load-normalized line voltage drop baseline model is as follows: ； in, Total active load power of the transformer area Next Normalized line voltage drop baseline for each photovoltaic user's load and The first The slope and intercept of the curve fitting parameters for each photovoltaic user.

3. The photovoltaic multi-level coordinated control method with household-level baseline normalization according to claim 2, characterized in that, In step S102, when constructing a load-normalized line voltage drop baseline model for photovoltaic users by curve fitting based on the measured voltage drop and the total active power of the distribution area during a specified time period, the first... The function expressions for calculating the slope and intercept in the curve fitting parameters for a photovoltaic user are as follows: ； ； in, The number of samples used to fit the sample set. To fit the total active load power of the substation area for the j-th sample in the sample set, For the fitted sample set, the first The measured voltage drop of the j-th sample of a photovoltaic user For the first The slope of the curve fitting parameters for each photovoltaic user To fit the sum of the total active load power of the transformer substations in the sample set, This is the sum of the measured pressure drops of all samples in the fitted sample set. For the first The intercept of the curve fitting parameters for each photovoltaic user.

4. The photovoltaic multi-level coordinated control method with household-level baseline normalization according to claim 1, characterized in that, In step S102, when constructing a load-normalized line voltage drop baseline model for each photovoltaic user based on curve fitting of the measured voltage drop and the total active power load of the distribution area during a specified time period, the specified time period is the near-zero output period, and the near-zero output period is the photovoltaic active power output. Below the near-zero output threshold The near-zero output threshold during the specified time period. These are parameters in the voltage autonomous control command.

5. The photovoltaic multi-level coordinated control method with household-level baseline normalization according to claim 1, characterized in that, Step S103 includes: S201, the concentrator of the target distribution area collects power grid data according to the first monitoring cycle. The power grid data includes the transformer outlet voltage and the total active load power of the distribution area. S202, calculate the corresponding load-normalized line voltage drop baseline based on the curve fitting parameters of each photovoltaic user; calculate the deviation between the measured voltage drop of each photovoltaic user and the load-normalized line voltage drop baseline based on the load-normalized line voltage drop baseline: ； in, For the first The deviation between the measured voltage drop of a photovoltaic user and the expected baseline. This is the transformer output voltage. For the first The grid connection voltage of each photovoltaic user Total active load power of the transformer area Next Normalized line voltage drop baseline for individual photovoltaic users' loads; S203, calculate the unit output voltage gain for each photovoltaic user in the target area: ； in, For the first The unit output voltage gain of a photovoltaic user for The absolute value, For the first The photovoltaic active power output of each photovoltaic user; S204, filter out units with voltage gain per unit output greater than a preset threshold. Photovoltaic users are considered photovoltaic users whose voltage exceeds the limit; S205, a voltage regulation authorization instruction is issued to the new energy power metering and monitoring terminal corresponding to the selected photovoltaic users. The voltage regulation authorization instruction carries a subset of regulation parameters. ={ , , , , , ~ , When the enable flag of the main station control is disabled or the control period has expired, the distribution area concentrator sends a voltage control authorization command with the enable flag disabled to the authorized new energy power metering and monitoring terminal. After receiving the voltage control authorization command with the enable flag disabled, the new energy power metering and monitoring terminal exits the local autonomous state and gradually restores active power output according to the preset recovery step size.

6. The photovoltaic multi-level coordinated control method with household-level baseline normalization according to claim 1, characterized in that, Step S104, which combines the acquired local grid connection point voltage with local autonomy, includes: [The text abruptly ends here, likely due to an incomplete sentence or a missing section.] The voltage exceeds the lowest-level over-limit threshold voltage carried in the voltage regulation authorization command. Flexible power regulation is performed, which includes first invoking the inverter to perform reactive power regulation according to the following formula: ； in, The adjusted reactive power. This represents the current reactive power. This is the direction sign for voltage exceeding limits; +1 is used for overvoltage and -1 for undervoltage. 1; To obtain the minimum value, To adjust the step size as a percentage, The rated capacity of the inverter. This is the upper limit of reactive power; if the reactive power regulation capacity is exhausted and the collected local grid connection point voltage is... It is still greater than the lowest level of over-limit threshold voltage carried in the voltage regulation authorization instruction. Then, the inverter is invoked to perform active power reduction according to the following formula: ； in, The reduced active power, The current active power, This is the upper limit of active power.

7. The photovoltaic multi-level coordinated control method with household-level baseline normalization according to claim 6, characterized in that, When performing local autonomy in step S104 by combining the acquired local grid connection point voltage, it also includes using the acquired local grid connection point voltage... Combined with the four-level over-limit threshold voltage carried in the voltage regulation authorization instruction ~ Determine the current control level Level 4 over-limit threshold voltage ~ satisfy ; If the local grid connection point voltage satisfy Then the control level =1; If the local grid connection point voltage satisfy Then the control level It is 2; If the local grid connection point voltage satisfy Then the control level It is 3; If the local grid connection point voltage satisfy Then the control level It is 4; The local grid connection point voltage obtained from the data acquisition The voltage exceeds the lowest-level over-limit threshold voltage carried in the voltage regulation authorization command. When performing flexible power regulation, including at the control level Flexible power adjustment is performed when the power is between 1 and 3.

8. The photovoltaic multi-level coordinated control method with household-level baseline normalization according to claim 7, characterized in that, In step S104, when performing local autonomy based on the acquired local grid connection point voltage, it also includes ensuring that the acquired local grid connection point voltage meets the following conditions: And the duration exceeds the preset time. The countdown to the circuit breaker tripping begins. During the countdown, if the local grid connection point voltage is collected... Falling back to voltage The following steps cancel the tripping operation, where the voltage... This refers to the highest-level over-limit threshold voltage carried in the voltage regulation authorization command. This refers to the delay parameter carried in the voltage regulation authorization command.

9. The photovoltaic multi-level coordinated control method with household-level baseline normalization according to claim 6, characterized in that, In step S104, when performing local autonomy based on the acquired local grid connection point voltage, it also includes using the acquired local grid connection point voltage... Meets recovery conditions And the duration exceeds the time limit. A gradual recovery strategy is implemented, in which... The recovery voltage carried in the voltage regulation authorization command, time The recovery time carried in the voltage regulation authorization command. For dynamic voltage offset, and have: = - ； in, This is the transformer output voltage. Rated voltage; The gradual recovery strategy includes invoking the inverter to perform active power recovery according to the following formula: ； in, This refers to the increase in active power during a single active power recovery. To obtain the minimum value, For percentage recovery step size, Rated active power, This is the upper limit of active power.

10. A photovoltaic multi-level coordinated control system with household-level baseline normalization, comprising interconnected microprocessors and memory, characterized in that, The microprocessor is programmed or configured to execute the photovoltaic multi-level coordinated control method with household baseline normalization as described in any one of claims 1 to 9.

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