A power distribution network low-frequency load shedding amount self-adaptive adjustment method based on distributed new energy output real-time sensing

Abstract

The application discloses a kind of based on distributed new energy output real-time sensing's distribution network low-frequency load shedding quantity self-adaptive adjustment method, according to the penetration of each feeder distributed power, feeder is automatically divided into high, medium, low penetration rate area;For medium, low penetration rate area feeder, real-time calculation net load and sorting, according to the basic power shortage, execute basic load shedding;After basic load shedding, when the distributed power output rate of change exceeds threshold value and system frequency drops synchronously, calculate the expected total amount of decline and feedforward additional load shedding;If frequency continues to drop and trigger lower threshold value, then cut off medium, low penetration rate area remaining cuttable feeder and carry out flexible load shedding to high penetration rate area feeder controllable load.The application can effectively avoid the loss of frequency support caused by the cutting of high distributed power penetration rate feeder, realize the dynamic matching of load shedding quantity and actual power shortage, and improve the accuracy and adaptability of distribution network low-frequency load shedding.

Description

Technical Field

[0001] This invention relates to the field of new energy grid connection and power grid safety and stability control technology, specifically to an adaptive adjustment method for low-frequency load shedding in distribution networks based on real-time sensing of distributed new energy output. Background Technology

[0002] Low-frequency load shedding is the last line of defense for power systems to prevent frequency collapse. When a large power deficit causes a continuous drop in frequency, the low-frequency load shedding device automatically cuts off a portion of the load according to a preset plan, restoring active power balance and preventing further frequency decline. With the increasing penetration of distributed photovoltaic (PV) and distributed wind power in distribution networks, the power flow and net load levels on distribution network feeders have undergone fundamental changes. Traditional low-frequency load shedding schemes are set based on fixed load shedding amounts, failing to consider the real-time output levels of distributed power sources within the feeders. This leads to two types of problems: when the output of distributed power sources is high, the net load on the feeder is low, and the actual load shedding amount according to the fixed plan is far less than expected, potentially resulting in insufficient load shedding and a continuous frequency drop; when feeders containing highly penetrated distributed power sources are shedding, the output of the distributed power sources is simultaneously cut off, exacerbating the system power deficit.

[0003] In the prior art, the invention patent with publication number CN118868142A considers the impact of a high proportion of new energy sources on the frequency characteristics of the distribution network and establishes a frequency response model of the distribution network containing distributed generation (DG) to optimize the load shedding cycle configuration. However, this method only considers the impact of DG during the offline setting stage and cannot adapt to real-time changes in DG output. The invention patent with publication number CN118970882A establishes a load importance evaluation system to prioritize load shedding according to importance, but does not consider the impact of DG output within the feeder on the actual load shedding effect. The invention patent with publication number CN116646944A uses the frequency change rate and system inertia to estimate the power deficit and adaptively calculate the load shedding amount, but does not distinguish the differences in DG penetration rates of different feeders, nor does it consider the dynamic impact of rapid changes in DG output on the power deficit. Summary of the Invention

[0004] The technical problem to be solved by this invention: Existing low-frequency load shedding technology does not take into account the real-time output level of distributed new energy sources in the distribution network, or the over-shearing or under-shearing caused by fixed load shedding schemes.

[0005] To address the aforementioned problems in existing technologies, a method for adaptive adjustment of low-frequency load shedding in distribution networks based on real-time sensing of distributed renewable energy output is provided. This method can sense the output level of distributed renewable energy in the distribution network in real time, configure load shedding strategies differently according to the penetration rate of distributed power sources, and adaptively adjust the low-frequency load shedding of the distribution network in response to rapid changes in the output of distributed power sources.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: An adaptive adjustment method for low-frequency load shedding in distribution networks based on real-time sensing of distributed renewable energy output, applicable to distribution networks with a high proportion of distributed renewable energy, includes the following steps: Calculate the distributed generation penetration rate of each feeder in the distribution network; The penetration rate zone of each feeder is determined based on the distributed power penetration rate of each feeder, and the penetration rate zone includes a high penetration rate zone, a medium penetration rate zone, and a low penetration rate zone. For feeders in low-permeability and medium-permeability zones, calculate the net load of each feeder and sort them according to the size of the net load to obtain the priority of each feeder; When the system frequency drops and triggers the low-frequency load shedding criterion, feeders are selected starting from the feeders with the highest priority until the net load accumulation value of the selected feeders is greater than or equal to the base power deficit, thus obtaining the first set of feeders to be cut off. The feeders in the first set of feeders to be cut off are then cut off. After the feeders in the first set of feeder cut-offs are cut off, the output change rate of distributed power sources and the system frequency change rate of each feeder are monitored in real time. If the feedforward triggering condition is met, the feedforward additional load reduction is calculated. Among the feeders that have not been cut off in the low-permeability and medium-permeability areas, feeders are selected starting from the feeder with the highest priority until the net load accumulation value of the selected feeder is greater than or equal to the feedforward additional load reduction, thus obtaining the second set of feeder cut-offs. The feeders in the second set of feeder cut-offs are then cut off. If the system frequency drops and triggers a backup load reduction criterion with a lower frequency threshold, the remaining uncut feeders in the low-permeability and medium-permeability zones will be disconnected, and a power reduction command will be sent to the controllable load in the feeders of the high-permeability zone.

[0007] Furthermore, the mathematical expression for calculating the distributed generation penetration rate of each feeder in the distribution network is as follows:

[0008] in, For the first i Distributed power penetration rate of single feeder lines; For the first i Total installed capacity of distributed power sources within each feeder line; For the first i The maximum load of the feeder.

[0009] Furthermore, when determining the penetration rate zone of each feeder based on its distributed power penetration rate, the distributed power penetration rate of each feeder is compared with the high penetration rate threshold and the low penetration rate threshold. If the distributed power penetration rate is less than the low penetration rate threshold, the corresponding feeder belongs to the low penetration rate zone. If the distributed power penetration rate is greater than or equal to the low penetration rate threshold and less than or equal to the high penetration rate threshold, the corresponding feeder belongs to the medium penetration rate zone. If the distributed power penetration rate is greater than the high penetration rate threshold, the corresponding feeder belongs to the high penetration rate zone.

[0010] Furthermore, when calculating the net load of each feeder, the total active power of the load on each feeder and the real-time active power output of the distributed generation are obtained in real time, and the difference between the two is calculated. The mathematical expression is as follows:

[0011] in, Let be the net load of the i-th feeder at time t; Let be the total active power of the feeder load at time t; The active power output of the distributed power source within the feeder at time t is the real-time output of the distributed power source.

[0012] Furthermore, when the feedforward triggering condition is met, the mathematical expression is as follows:

[0013] in, It is the total output change rate of all distributed generation sources within the distribution network, specifically the sum of the output change rates of distributed generation sources along each feeder. It is the rate of change of system frequency. It refers to the total installed capacity of distributed power sources within the distribution network. This is the threshold coefficient for the rate of change of output.

[0014] Furthermore, the calculation of feedforward additional load reduction includes: The mathematical expression for calculating the total expected decrease in distributed power generation output is as follows:

[0015] in, For the prediction time window; The feedforward load reduction is calculated based on the expected total decrease in distributed power output, and the mathematical expression is as follows:

[0016] in, This is the feedforward compensation coefficient.

[0017] Furthermore, when cutting off the remaining uncut feeders in the low-permeability and medium-permeability zones, and sending a power reduction command to the controllable load in the feeders of the high-permeability zone, the specific steps include: Wait for the system frequency to drop to the first backup load reduction threshold, then cut off the remaining uncut feeders in the low-permeability and medium-permeability areas; Once the system frequency drops to a second backup load reduction threshold below the first backup load reduction threshold, a power reduction command is sent to the controllable load within the feeder in the high-penetration area.

[0018] This invention also proposes an adaptive adjustment system for low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output. The system includes interconnected processors and computer-readable storage media. The computer-readable storage media stores a computer program, which is executed by the processor to implement the adaptive adjustment method for low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output.

[0019] The present invention also proposes a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the aforementioned method for adaptive adjustment of low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output.

[0020] The present invention also proposes a computer program product, including a computer program, which, when executed by a processor, implements the aforementioned adaptive adjustment method for low-frequency load shedding in distribution networks based on real-time sensing of distributed renewable energy output.

[0021] Compared with the prior art, the advantages of the present invention are as follows: This invention addresses the technical shortcomings of traditional low-frequency load shedding, which is based on fixed load shedding amounts and fails to consider the real-time output level of distributed new energy sources within the feeder, leading to over- or under-shearing. Furthermore, it addresses the issue that cutting off feeders with high penetration rates of distributed power sources can exacerbate system power deficits. The invention employs a differentiated load shedding strategy based on distributed power source penetration rate zoning. This strategy automatically divides the distribution network feeders into high-penetration, medium-penetration, and low-penetration zones. This ensures that feeders in high-penetration zones do not participate in feeder shedding but instead undergo flexible load shedding through controllable load control, thus avoiding the frequency support loss and power deficit deterioration caused by cutting off high-penetration feeders. Based on this, the net load of feeders in low-to-medium penetration areas is calculated in real time and dynamically prioritized for load shedding according to their magnitude, ensuring precise matching between the base load shedding and the actual power deficit. By monitoring the rate of change of distributed generation output and the rate of change of system frequency in real time, after the first round of base load shedding, when the rate of change of distributed generation output and the rate of change of system frequency meet the feedforward trigger condition, feeders are additionally cut off independently of the frequency threshold, responding in advance to the dynamic increase in power deficit caused by a sudden drop in distributed generation output. This method adopts a step-by-step strategy of "base load shedding and feedforward addition," allowing the load shedding to be dynamically adjusted according to the actual change in power deficit. This avoids both frequency overshoot caused by one-time over-cutting and continuous frequency drop caused by under-cutting, effectively suppressing secondary frequency drops and achieving rapid recovery of system frequency and dynamic reconstruction of active power balance. This invention is applicable to 10kV and above distribution networks with a high proportion of distributed renewable energy. With the continuous increase in the penetration rate of distributed renewable energy, it has broad engineering application prospects and promotional value. Attached Figure Description

[0022] Figure 1 This is the overall flowchart of the method of the present invention.

[0023] Figure 2 This is a schematic diagram of the feedforward load reduction pre-adjustment principle of the DG output change rate of the present invention.

[0024] Figure 3 These are comparison curves of the system frequency response during simulation verification.

[0025] Figure 4 These are the dynamic change curves of the net load of each feeder in the simulation verification.

[0026] Figure 5 It is the curve showing the change in total output of distributed power sources during simulation verification.

[0027] Figure 6 It is a curve comparing load reduction and power deficit in the simulation verification. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0029] This embodiment proposes an adaptive adjustment method for low-frequency load shedding in distribution networks based on real-time sensing of distributed renewable energy output. It is applied to distribution networks with a high proportion of distributed renewable energy and aims to achieve dynamic matching between load shedding and actual power deficit, thereby avoiding frequency support loss caused by cutting feeders with high distributed power penetration.

[0030] like Figure 1 As shown, the method includes the following steps: Step 1: Calculate the distributed generation penetration rate of each feeder in the distribution network. Specifically, collect the active power of the distributed generation grid connection point and the total active power at the feeder outlet of each feeder in the distribution network, and calculate the distributed generation penetration rate of each feeder, which is the ratio of the total installed capacity of distributed generation in the feeder to the maximum load of the feeder.

[0031] There are N feeders in the distribution network. i The total installed capacity of distributed power sources connected within the feeder line is P DG,i,rated The maximum load of the feeder is P L,i,max The active power measurements of each feeder's DG (Distributed Generation) grid connection point are collected in real time through the distribution automation system to calculate the first... i Distributed power penetration rate of single feeder: (1) in, For the first i Distributed power penetration rate of single feeder lines; For the first i Total installed capacity of distributed power sources within each feeder line; For the first i The maximum load of the feeder.

[0032] Step 2: Determine the penetration rate zone of each feeder based on the distributed power penetration rate of each feeder. The penetration rate zone includes a high penetration rate zone, a medium penetration rate zone, and a low penetration rate zone.

[0033] In this embodiment, the distributed power penetration rate of each feeder is compared with high penetration rate thresholds and low penetration rate thresholds. If the distributed power penetration rate is less than the low penetration rate threshold, the corresponding feeder belongs to the low penetration rate zone. If the distributed power penetration rate is greater than or equal to the low penetration rate threshold and less than or equal to the high penetration rate threshold, the corresponding feeder belongs to the medium penetration rate zone. If the distributed power penetration rate is greater than the high penetration rate threshold, the corresponding feeder belongs to the high penetration rate zone. Differentiated load reduction strategies are configured for different zones. The specific implementation process is as follows: Two penetration rate thresholds are set as follows: the first threshold η HSecond threshold η L The feeder is divided into three zones based on penetration rate: (2) in, For high penetration rates, a threshold of 50% is recommended. For low penetration, a threshold of 10% is recommended.

[0034] The differentiated load reduction strategies for each partition are as follows: (1) High penetration area (H zone): The feeder does not participate in feeder cut-off load reduction. When this area needs to contribute to load reduction, a power reduction command is sent to the controllable loads within the feeder (such as electric vehicle charging piles, air conditioning loads, energy storage charging loads, etc.) through the distribution automation system to achieve flexible load reduction. The controllable load reduction of the feeder in H zone is: (3) in, Let be the number of controllable loads within the i-th feeder; This represents the power reduction of the kth controllable load.

[0035] (2) Medium permeability zone (M zone): The feeder part participates in feeder shedding, and the shedding amount is calculated based on the net load.

[0036] (3) Low permeability zone (L zone): The feeder participates in feeder load shedding first, and the load shedding amount is approximately equal to the total load of the feeder.

[0037] Step 2 automatically divides the distribution network feeders into three zones based on the distributed generation penetration rate of each feeder: a high penetration zone (feeders with penetration rates greater than the high penetration rate threshold), a medium penetration zone (feeders with penetration rates between the low and high penetration rate thresholds), and a low penetration zone (feeders with penetration rates less than the low penetration rate threshold). Differentiated load shedding strategies are configured for each zone: feeders in the high penetration zone do not participate in feeder shedding; load shedding is achieved by reducing controllable load power within the feeder; feeders in the medium penetration zone partially participate in load shedding, with the shedding amount calculated based on net load; feeders in the low penetration zone are given priority for feeder shedding.

[0038] Step 3: For feeders in low-permeability and medium-permeability areas, calculate the net load of each feeder. Specifically, calculate the net load of each feeder in real time, which is the difference between the total active power of the feeder and the active power output of the distributed power sources within the feeder. This serves as the actual load reduction effect when the feeder is disconnected.

[0039] In this embodiment, the net load of the i-th feeder is defined as the difference between the total active power of the feeder and the real-time active power output of the distributed power source within the feeder: (4) in, Let be the net load of the i-th feeder at time t; Let be the total active power of the feeder load at time t; The active power output of the distributed power source within the feeder at time t is the real-time output of the distributed power source.

[0040] Net load reflects the actual load reduction effect when the feeder is disconnected. When the DG output is high, the net load is small, and the actual load reduction when disconnecting the feeder is less than the total load of the feeder; when the DG output is zero, the net load is equal to the total load of the feeder.

[0041] Step 4: Prioritize each feeder according to its net load. Specifically, in the medium and low permeability zones, dynamically prioritize the feeder load reduction according to its net load from largest to smallest. Feeders with larger net loads are given priority for load reduction, achieving the required load reduction with the fewest feeder disconnections.

[0042] Specifically, the feeders for areas M and L are arranged in descending order of net load: (5) in, For sorting mapping functions, The feeder with the largest net load (highest priority) is selected, and M represents the total number of feeders participating in the sorting.

[0043] The priority ranking is dynamically updated within each load reduction cycle, with the update cycle consistent with the DG output sampling cycle. A typical value can be set to 1 second to ensure that the priority ranking reflects the latest feeder net load status. Feeders with larger net loads participate in load reduction first, achieving the required load reduction with the fewest number of feeders disconnected.

[0044] Step 5: When the system frequency drops and triggers the low-frequency load shedding action criterion, start selecting feeders from the feeders with the highest priority until the net load accumulation value of the selected feeders is greater than or equal to the base power deficit, and obtain the first set of feeders to be cut off. Then, cut off the feeders in the first set of feeders to be cut off.

[0045] In step 5 of this embodiment, when the system frequency drops and triggers the first round of low-frequency load shedding action criteria, the feeder combination to be cut off in the first round is determined and the load shedding action is executed based on the basic power deficit and the load shedding priority after dynamic sorting in step 4.

[0046] The first round of load reduction was based solely on the base power deficit. P deficit,base The feeder to be cut off is determined, excluding feedforward compensation. The foundation load reduction can be estimated based on the system frequency deviation and equivalent inertia: the power deficit is estimated using the frequency change rate df / dt and the system equivalent inertia time constant H, meaning the foundation load reduction equals the estimated power deficit. When the system is equipped with a PMU or frequency measurement device, df / dt can be directly obtained for online calculation.

[0047] Starting with the feeders with the highest priority, the net load is accumulated to determine the set of feeders to be cut off, S1, which can be called the first set of feeders to be cut off for distinction: (6) in, The minimum number of feeders required to meet the foundation load reduction requirements.

[0048] Step 6: After the feeders in the first set of cut-off feeders are cut off, monitor the rate of change of distributed power output and the rate of change of system frequency for each feeder in real time. If the feedforward triggering condition is met, calculate the feedforward additional load reduction. Among the feeders that have not been cut off in the low-permeability and medium-permeability areas, select feeders starting from the feeder with the highest priority until the net load accumulation of the selected feeder is greater than or equal to the feedforward additional load reduction, thus obtaining the second set of cut-off feeders. Cut off the feeders in the second set of cut-off feeders to achieve feedforward additional load reduction, and then proceed to Step 7 for backup load reduction. If the feedforward triggering condition is not met, this step can be skipped and the process can proceed directly to Step 7 for backup load reduction.

[0049] In step 6, the feedforward trigger condition is: the output of the distributed generation exceeds a set proportion of its rated capacity within a preset time window, and the system frequency change rate remains negative within the same time window. By monitoring the output change rate and system frequency change rate of each feeder in real time, when the absolute value of the output change rate of the distributed generation exceeds a set threshold and the system frequency change rate is negative, it is determined that the output of the distributed generation is rapidly decreasing and will exacerbate the system power deficit. The expected total decrease in the output of the distributed generation is calculated, and feedforward additional feeders are disconnected. The additional feeders to be disconnected are selected from the feeders not disconnected in the first round according to net load priority. The specific implementation process is as follows: Calculate the total output change rate of all distributed power sources in the distribution network based on the output change rate and the prediction time window: (7) Simultaneously monitor the system frequency change rate df / dt. Initiate feedforward-based load shedding / loading when the following feedforward trigger conditions are met: (8) in, The output change rate threshold coefficient is recommended to be 0.06 / s (i.e., 6% of the rated capacity per second). This refers to the total installed capacity of distributed power sources within the distribution network.

[0050] After feedforward triggering, calculate the total expected decrease in DG output: (9) in, A 5-second time window is recommended for prediction. The expected decrease has an upper limit, not exceeding the total rated output of DG.

[0051] The feedforward additional load reduction is: (10) in, The feedforward compensation coefficient is recommended to be 0.9, taking into account the safety margin of prediction error.

[0052] The feeders to be additionally cut off from the feeders not cut off in the first round are selected according to net load priority to determine the additional cut-off set S. ff This can be distinguished as the second set of cut-off feeders: (11) The feedforward load shedding is independent of the frequency threshold triggering and is actively executed when a rapid decrease in DG output is detected. This stepwise strategy of basic load shedding and feedforward addition avoids frequency overshoot caused by a one-time over-cut and can respond promptly to the increase in power deficit caused by the decrease in DG output.

[0053] Step 7: After the first round of load reduction, if the system frequency drops and triggers the backup load reduction action criterion of a lower frequency threshold, the remaining uncut feeders in the low-permeability and medium-permeability areas are cut off, and a power reduction command is sent to the controllable load in the feeder of the high-permeability area to start the flexible load reduction of the controllable load in the high-permeability area, thereby realizing backup load reduction.

[0054] Step 7 can perform multiple rounds of backup load shedding, using the traditional frequency threshold + delay method: If the system frequency continues to drop, triggering a backup load shedding round at a lower frequency threshold, the remaining cuttable feeders will be disconnected. For example, wait for the system frequency to drop to the first backup load shedding threshold (such as the 48.8Hz threshold), then perform backup load shedding, i.e., the second round of load shedding, disconnecting the remaining uncut feeders in the low-permeability zone (L zone) and the medium-permeability zone (M zone); When the frequency drops below the minimum threshold, the controllable load reduction in the high-penetration area is initiated. For example, wait for the system frequency to drop to the second backup load reduction threshold (such as the 48.6Hz threshold) which is less than the first backup load reduction threshold, and then perform the backup load reduction again, i.e., the third round of load reduction. Send a power reduction command to the controllable load in the feeder of the high-penetration area (H area), and cut off a specified proportion (such as 30%) of the total load of the feeder in the H area as the final backup according to the controllable load reduction amount calculated by formula (3).

[0055] To verify the effectiveness of the method in this embodiment, a simulation verification was conducted using a 10kV distribution network in a certain region as an example. The simulation system includes 6 feeders, a system base capacity of 30MW, an equivalent inertia time constant H of 4s, a load damping coefficient D of 2.0pu / pu, a governor time constant of 5s, a droop coefficient of 5%, and a maximum regulation of 3MW. The parameters of each feeder are shown in Table 1. The total system load is 27.0MW, the total installed DG capacity is 8.9MW, and the total penetration rate is 33%. A high penetration rate threshold was set. η H The low penetration threshold η is 50%. L The figure is 10%. Simulation scenario: At time t=0, the system experiences a power deficit of 5MW, meaning the upstream grid loses one generator; simultaneously, at time t=2s, due to cloud cover, the photovoltaic output drops from 80% to 24% of the rated value within 5 seconds, which is 30% of the rated value. The decrease in DG output results in an additional power deficit of approximately 5MW, and the total power deficit eventually reaches approximately 10MW.

[0056] The method of this embodiment was executed in a simulation case, and the results of each step are as follows: The calculated penetration rates of each feeder obtained through step 1 are shown in Table 1.

[0057] Table 1. Simulation System Feeder Parameters

[0058] Through step 2, the partitioning results are as follows: F1 (80%) and F2 (67%) are H zones; F3 (38%) and F4 (17%) are M zones; and F5 (6%) and F6 (3%) are L zones.

[0059] Through step 3, the net load of each feeder is calculated at t=0. The DG output is 80% of the installed capacity: F1 net load is 1.8MW (H area); F2 net load is 1.4MW (H area); F3 net load is 2.8MW; F4 net load is 5.2MW; F5 net load is 4.76MW; F6 net load is 3.92MW.

[0060] Through step 4, the feeders in the M and L zones are arranged in descending order of net load: F4 (5.2MW) > F5 (4.76MW) > F6 (3.92MW) > F3 (2.8MW).

[0061] In step 5, the system frequency drops below 49.0Hz at t≈1s, triggering the first round of load shedding after a 0.3s delay. The base power deficit is 5MW, accumulated starting from the feeder with the highest priority: F4 is 5.2MW ≥ 5.0MW. Disconnecting F4 will meet the requirements of the first round of load shedding, with an actual load shedding of 5.2MW.

[0062] Through step 6, such as Figure 2As shown, the DG output is 80% of the rated value during normal operation; at t=2s, cloud cover occurs, and the DG output drops sharply from 80% to 24% (i.e., 30% of the rated value) within 5 seconds. At t≈2.5s, the photovoltaic output begins to decline rapidly, and the rate of change of the total DG output suddenly increases to (8.9×0.8 - 8.9×0.24) / 5 ≈ 0.998MW / s.

[0063] Where, |d P DG / dt| = 0.998MW / s>α×P rated = 0.534MW / s, and df / dt<0, satisfying the feedforward trigger condition. It is determined that the output of the distributed power source is rapidly decreasing and will exacerbate the system power deficit. Based on this, the expected decrease Δ is derived. P DG,pred The capacity is 4.99MW, with additional load reduction for feedforward. P shed,ff The total load reduction is 4.49MW. From the feeders not cut off in the first round, F5 (4.76MW ≥ 4.49MW) is selected, and F5 is subsequently cut off. The total load reduction is then 9.96MW, which basically matches the final power deficit of approximately 10MW.

[0064] Compared with the traditional approach, which is set to a fixed load shedding amount, the traditional approach cuts off 4MW of total load from F6 in the first round (49.0Hz) and 5MW of total load from F5 in the second round (48.8Hz), for a total shedding of 9MW. The traditional approach cuts off based on total load rather than net load and has no feedforward mechanism, resulting in a delayed response when the output of the distributed generator (DG) drops sharply and an inability to adapt to the increased power deficit after the DG output drops sharply.

[0065] After adopting the method of this embodiment, the load reduction is dynamically adjusted to 5.0 + 0.9 × 4.99 = 9.49 MW, and feeders F4 and F5 (with a total net load of approximately 9.96 MW ≥ 9.49 MW) are selected from the feeders not disconnected in the first round according to net load priority for additional disconnection. Figure 3 As shown, through feedforward adjustment, the lowest system frequency point increased from 48.5Hz to 49.2Hz, and the frequency recovery time was shortened by approximately 40%. It is evident that after adopting the method of this embodiment, the lowest system frequency point is higher than that of the traditional scheme, and the frequency recovery is faster with less overshoot. This embodiment's method, through a feedforward mechanism, adds load reduction in the early stages of DG output reduction, avoiding a secondary frequency drop.

[0066] like Figure 4 As shown, the net load of each feeder is dynamically adjusted according to the output of the DG. The DG output of feeders (F1, F2) in area H continues to provide frequency support for the system during the load reduction process. Figure 5 As shown, the total output of the DG decreases from 7.12MW to 2.14MW within the time interval t=2~7s. (As...) Figure 6As shown, the load reduction amount of the method in this embodiment is dynamically matched with the actual power deficit, while the fixed load reduction amount of the traditional solution cannot adapt to the dynamic changes in the deficit.

[0067] Furthermore, this embodiment also proposes an adaptive adjustment system for low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output. The system includes interconnected processors and a computer-readable storage medium. The computer-readable storage medium stores a computer program, which is executed by the processor to implement the adaptive adjustment method for low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output described in this embodiment. The system includes: The data acquisition module is used to collect the active power of the distributed power source at the grid connection point of each feeder in the distribution network, the total active power of the feeder, and the system frequency signal. The penetration rate zoning module is used to calculate the penetration rate of distributed power sources for each feeder and automatically divide them into high penetration rate zones, medium penetration rate zones, and low penetration rate zones. The net load calculation and sorting module is used to calculate the net load of each feeder in real time and dynamically sort the load reduction priority according to the net load from largest to smallest. The feedforward pre-adjustment module is used to monitor the output change rate of distributed power sources and the system frequency change rate, and to additionally cut off the feeder when the feedforward triggering condition is met. The load reduction execution module is used to determine the combination of feeders to be cut based on the basic load reduction requirements and the feedforward addition requirements, and to perform the load reduction action when the frequency is triggered or the feedforward is triggered.

[0068] Furthermore, this embodiment also proposes a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the adaptive adjustment method for low-frequency load shedding in the distribution network based on real-time sensing of distributed renewable energy output described in this embodiment.

[0069] Furthermore, this embodiment also proposes a computer program product, including a computer program, which, when executed by a processor, implements the adaptive adjustment method for low-frequency load shedding in the distribution network based on real-time sensing of distributed renewable energy output described in this embodiment.

[0070] In summary, this invention addresses the problem that traditional fixed low-frequency load shedding schemes cannot adapt to dynamic changes in feeder net load after a high proportion of distributed renewable energy (DG) is integrated into the distribution network. It proposes a method and system for adaptive adjustment of low-frequency load shedding in the distribution network based on real-time sensing of DG output. This method employs a differentiated load shedding strategy based on DG penetration rate zoning, dynamic priority ranking based on feeder net load, and feedforward supplementary load shedding based on the DG output change rate. The advantages of this invention are: 1. By employing automatic zoning based on DG penetration rate and a differentiated load reduction strategy, the frequency support loss caused by cutting off feeders with high DG penetration rates was avoided, thus preserving the positive contribution of distributed generation to the system frequency. Simulation results show that the DG output of feeders (F1, F2) in region H continuously provides frequency support to the system during load reduction.

[0071] 2. By calculating the feeder net load in real time and dynamically prioritizing it, the actual load reduction amount of each load shedding action is precisely matched with the expected load reduction amount, avoiding over- or under-shearing caused by neglecting the output of DG in traditional solutions. As shown in the simulation example, after sorting by net load, only two feeders (F4 and F5, with a total net load of 9.96MW) need to be cut off to meet the load reduction requirement of about 10MW.

[0072] 3. By adopting a step-by-step strategy of "basic load reduction + feedforward addition", the first round is to accurately cut off the basic deficit. When the feedforward mechanism detects a rapid decrease in DG output, it actively adds additional cut-off. This avoids frequency overshoot caused by one-time over-cutting and can respond in a timely manner to the increase in power deficit caused by the decrease in DG output, thus achieving dynamic and accurate matching between load reduction and power deficit.

[0073] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can 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 application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. 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, create a machine for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The 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 1The 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.

[0074] 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 method for adaptive adjustment of low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output, characterized in that, The method is applied to distribution networks containing a high proportion of distributed renewable energy sources, and includes the following steps: Calculate the distributed generation penetration rate of each feeder in the distribution network; The penetration rate zone of each feeder is determined based on the distributed power penetration rate of each feeder, and the penetration rate zone includes a high penetration rate zone, a medium penetration rate zone, and a low penetration rate zone. For feeders in low-permeability and medium-permeability zones, calculate the net load of each feeder and sort them according to the size of the net load to obtain the priority of each feeder; When the system frequency drops and triggers the low-frequency load shedding criterion, feeders are selected starting from the feeder with the highest priority until the net load accumulation value of the selected feeder is greater than or equal to the base power deficit, thus obtaining the first set of feeders to be cut off. The feeders in the first set of feeders to be cut off are then cut off. After the feeders in the first set of feeder cut-offs are cut off, the output change rate of distributed power sources and the system frequency change rate of each feeder are monitored in real time. If the feedforward triggering condition is met, the feedforward additional load reduction is calculated. Among the feeders that have not been cut off in the low-permeability and medium-permeability areas, feeders are selected starting from the feeder with the highest priority until the net load accumulation value of the selected feeder is greater than or equal to the feedforward additional load reduction, thus obtaining the second set of feeder cut-offs. The feeders in the second set of feeder cut-offs are then cut off. If the system frequency drops and triggers a backup load reduction criterion with a lower frequency threshold, the remaining uncut feeders in the low-permeability and medium-permeability zones will be disconnected, and a power reduction command will be sent to the controllable load in the feeders of the high-permeability zone.

2. The adaptive adjustment method for low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output as described in claim 1, characterized in that, The mathematical expression for calculating the distributed generation penetration rate of each feeder in a distribution network is as follows: in, For the first i Distributed power penetration rate of single feeder lines; For the first i Total installed capacity of distributed power sources within each feeder line; For the first i The maximum load of the feeder.

3. The adaptive adjustment method for low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output as described in claim 1, characterized in that, When determining the penetration rate zone of each feeder based on its distributed power penetration rate, the specific method is to compare the distributed power penetration rate of each feeder with the high penetration rate threshold and the low penetration rate threshold. If the distributed power penetration rate is less than the low penetration rate threshold, the corresponding feeder belongs to the low penetration rate zone. If the distributed power penetration rate is greater than or equal to the low penetration rate threshold and less than or equal to the high penetration rate threshold, the corresponding feeder belongs to the medium penetration rate zone. If the distributed power penetration rate is greater than the high penetration rate threshold, the corresponding feeder belongs to the high penetration rate zone.

4. The adaptive adjustment method for low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output as described in claim 1, characterized in that, When calculating the net load of each feeder, the total active power of the load on each feeder and the real-time active power output of the distributed generation are obtained in real time, and the difference between the two is calculated. The mathematical expression is as follows: in, Let be the net load of the i-th feeder at time t; Let be the total active power of the feeder load at time t; The active power output of the distributed power source within the feeder at time t is the real-time output of the distributed power source.

5. The adaptive adjustment method for low-frequency load shedding in distribution networks based on real-time sensing of distributed renewable energy output according to claim 1, characterized in that, When the feedforward triggering condition is met, the mathematical expression is as follows: in, It is the total output change rate of all distributed generation sources within the distribution network, specifically the sum of the output change rates of distributed generation sources along each feeder. It is the rate of change of system frequency. It refers to the total installed capacity of distributed power sources within the distribution network. This is the threshold coefficient for the rate of change of output.

6. The adaptive adjustment method for low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output, as described in claim 5, is characterized in that... When calculating the feedforward additional load reduction, the following is included: The mathematical expression for calculating the total expected decrease in distributed power generation output is as follows: in, For the prediction time window; The feedforward load reduction is calculated based on the expected total decrease in distributed power output, and the mathematical expression is as follows: in, This is the feedforward compensation coefficient.

7. The adaptive adjustment method for low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output as described in claim 1, characterized in that, When cutting off the remaining uncut feeders in the low-permeability and medium-permeability zones, and sending a power reduction command to the controllable load in the feeders of the high-permeability zone, the specific steps include: Wait for the system frequency to drop to the first backup load reduction threshold, then cut off the remaining uncut feeders in the low-permeability and medium-permeability areas; Once the system frequency drops to a second backup load reduction threshold below the first backup load reduction threshold, a power reduction command is sent to the controllable load within the feeder in the high-penetration area.

8. A distribution network low-frequency load shedding adaptive adjustment system based on real-time sensing of distributed renewable energy output, characterized in that, The device includes an interconnected processor and a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program that is executed by the processor to implement the adaptive adjustment method for low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the adaptive adjustment method for low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output as described in any one of claims 1 to 7.

10. A computer program product, characterized in that, The method includes a computer program that, when executed by a processor, implements the adaptive adjustment method for low-frequency load shedding in a distribution network based on real-time sensing of distributed renewable energy output, as described in any one of claims 1 to 7.

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