A non-fixed load precise removal method based on load control fairness and effectiveness considerations

Abstract

The present invention relates to the field of load control, and in particular to a non-fixed load precision shedding method based on the consideration of fairness and effectiveness of load control. It comprises: collecting the power grid system frequency, calculating the frequency change rate, and judging whether to send a "prepare to shear load" instruction to all substations by monitoring the power grid system frequency and frequency change rate, and entering the load shedding amount calculation stage, calculating the load amount that needs to be sheared off in each area through a dynamic weighted load precision shedding algorithm, and calculating the total load shedding amount; based on the load amount that needs to be sheared off in each area, the substation optimizes the shedding combination of load lines in the area, and after the optimization is completed, the substation executes shedding, and the main station monitors the power grid system frequency and frequency change rate after shedding, and judges whether the locking conditions are met to stop further shedding. It solves the technical problem that power grid frequency monitoring mostly relies on low sampling rate equipment, which is difficult to capture rapidly changing frequency dynamics, resulting in delayed or misjudgment of instability detection.

Description

Technical Field

[0001] The present invention relates to the field of load control, and in particular to a non-fixed load precision removal method based on considerations of load control fairness and effectiveness. Background Art

[0002] With the rapid development of power systems and the profound transformation of energy structures, the safe and stable operation of power systems faces unprecedented challenges. In particular, with the integration of a high proportion of renewable energy, the widespread use of distributed power sources, and the marketization of electricity, the load characteristics of power systems are becoming increasingly complex, diverse, and dynamic. Traditional fixed load shedding strategies, due to their lack of flexibility and inattention to differences in load characteristics, are unable to meet the fairness, effectiveness, and accuracy requirements of modern power systems. Therefore, non-fixed load shedding methods, based on considerations of load control fairness and effectiveness, have emerged as a research hotspot in the field of power system operation and control.

[0003] Non-stationary load precision shedding methods refer to control strategies that dynamically determine the load shedding targets, load amounts, and timing based on real-time system status, load characteristics, and optimization objectives. Compared with traditional fixed methods, non-stationary methods offer greater flexibility and adaptability, better addressing the operational demands of modern power systems. While ensuring system stability, they can improve user experience and resource efficiency, supporting the intelligent transformation of power systems. In the future, with the further development of artificial intelligence, big data, and communication technologies, they are expected to play a greater role in power system operation and control, laying a solid technical foundation for achieving a safe, green, and efficient smart grid.

[0004] However, the above-mentioned existing load shedding methods still have technical problems such as difficulty in quickly responding to frequency instability caused by fluctuations in renewable energy, which can easily lead to large-scale power outages or grid system collapse; insufficient regional management and coordinated control of the grid; and insufficient fairness and accuracy in load shedding. Summary of the Invention

[0005] The present invention provides a non-fixed load precision shedding method based on the consideration of load control fairness and effectiveness, so as to solve the technical problems that power grid frequency monitoring mostly relies on low sampling rate equipment, which is difficult to capture rapidly changing frequency dynamics, resulting in delayed or misjudgment of instability detection; based on static allocation, it ignores regional load characteristics and priority differences, which easily leads to excessive shedding of high-priority areas or insufficient shedding of low-priority areas; and the line shedding decision of existing substations mostly relies on manual experience or simple rules, making it difficult to find the optimal combination among multiple lines.

[0006] The present invention provides a non-fixed load precision removal method based on load control fairness and effectiveness considerations, specifically including the following technical solutions:

[0007] A non-fixed load precise removal method based on load control fairness and effectiveness considerations includes the following steps:

[0008] S1. The power grid is divided into regions based on physical topology. Each region is managed and controlled by a substation, while the master station coordinates and controls the load between regions. The system frequency is collected, the frequency change rate is calculated, and the system frequency and frequency change rate are monitored to determine whether to send a "prepare to shed load" command to all substations.

[0009] S2. Following the "Prepare for Load Shedding" command, the load shedding calculation phase begins. Based on the master station's real-time monitoring of the grid system frequency and frequency change rate, combined with preset regional priority weights, a dynamic weighted load shedding algorithm is used to calculate the load shedding required for each region. A maximum load shedding amount is preset, and the total load shedding amount is calculated, imposing a total load constraint.

[0010] S3. Based on the load shedding required in each area, the substation optimizes the load shedding combination within the area. After optimization, the substation executes shedding. The master station monitors the grid system frequency and frequency change rate after shedding to determine whether the blocking conditions are met to stop further shedding.

[0011] Preferably, the S1 specifically includes:

[0012] The load of each load line in the area is collected through the substation, and the substation presets the load line priority weight according to the grid user profile and priority power supply agreement; the total load of each area is collected through the main station, and the main station presets the regional priority weight according to the regional load characteristics.

[0013] Preferably, the S1 specifically includes:

[0014] Based on the grid system frequency and frequency change rate, a frequency threshold and a frequency change rate threshold are set, the grid system frequency is compared with the frequency threshold, and the frequency change rate is compared with the frequency change rate threshold to determine whether to send a "prepare to shed load" instruction to all substations.

[0015] Preferably, the S1 specifically includes:

[0016] When the grid system frequency is lower than the frequency threshold and the absolute value of the frequency change rate exceeds the frequency change rate threshold, the master station considers that the grid system frequency stability is threatened and immediately sends a "prepare to shed load" instruction to all substations, entering the load shedding amount calculation stage. When any condition is not met, the master station continues to monitor the grid system frequency and frequency change rate.

[0017] Preferably, the S2 specifically includes:

[0018] In the implementation process of the dynamic weighted load precise removal algorithm, the frequency deviation between the current power grid system frequency and the rated frequency is calculated, and the frequency deviation is divided by the deviation threshold for normalization; at the same time, the absolute value of the frequency change rate is divided by the frequency change rate threshold to reflect the urgency of dynamic instability of the power grid system.

[0019] Preferably, the S2 specifically includes:

[0020] In the implementation process of the dynamic weighted load precise removal algorithm, the frequency deviation and the frequency change rate are weighted and summed as the weighted instability factor to comprehensively consider the influence of static instability and dynamic instability, and a priority adjustment factor is introduced to adjust the priority of each area.

[0021] Preferably, the S2 specifically includes:

[0022] In the implementation of the dynamic weighted load precise shedding algorithm, the current total load, the weighted sum of the frequency deviation and the frequency change rate, and the priority adjustment factor are combined to obtain the load that needs to be shedding in each area.

[0023] Preferably, the S3 specifically includes:

[0024] The master station distributes the calculated load shedding amount for each region to the corresponding regional substation, which then optimizes the load shedding combination within the region. During the optimization process, the substation ensures that the load shedding amount is equal to the allocated load shedding amount, and that the shedding amount of each load line does not exceed the current load of the load line. The optimal load line combination is found through iterative solution.

[0025] Preferably, the S3 specifically includes:

[0026] The locking conditions include two aspects: one is that the frequency of the power grid system reaches or exceeds the frequency threshold; the other is that the absolute value of the frequency change rate is less than the frequency change rate threshold; when the two locking conditions are met at the same time, the master station sends a "stop removal" instruction to all substations through the optical fiber network. When any condition is not met, the load amount that needs to be removed in each area is recalculated and a new round of removal is started.

[0027] The beneficial effects of the technical solution of the present invention are:

[0028] 1. The master station monitors the power grid system frequency and frequency change rate in real time, quickly monitors frequency instability caused by fluctuations in renewable energy output or emergencies, and promptly triggers the "prepare to shed load" command, ensuring accurate identification and rapid response to power grid system frequency anomalies, effectively preventing frequency collapse and maintaining the overall stability of the power grid system.

[0029] 2. A dynamic weighted load shedding algorithm is used to accurately shear off loads, comprehensively considering frequency deviation and frequency change rate, quantifying the degree of static and dynamic instability of the power grid system, and combining regional priority weights and nonlinear adjustment mechanisms to rationally allocate the load shedding required in each region. This avoids the problems of mis-shrinking critical loads or insufficient shedding in traditional load shedding methods, ensuring that the shedding process is both efficient and fair, and protecting the power supply needs of important users to the greatest extent possible.

[0030] 3. Based on the load shedding amount allocated by the master station, the substation optimizes the shedding combination of specific load lines in the area through a linear programming algorithm, giving priority to protecting high-priority load lines and reducing social and economic losses. The rapid response capabilities of intelligent circuit breakers and distribution automation switches further shorten the shedding action time and improve the accuracy and execution efficiency of load management.

[0031] 4. The master station imposes a total constraint by presetting the maximum load removal to ensure that the load removal is within a safe range, avoiding instability or secondary failures of the power grid system caused by excessive load removal. At the same time, the setting of the locking condition enables the master station to stop load removal in time when the frequency returns to normal or the dynamic instability is alleviated, preventing unnecessary load loss and optimizing the economic efficiency of the power grid operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flow chart of a non-fixed load precision removal method based on load control fairness and effectiveness considerations described in the present invention. DETAILED DESCRIPTION

[0033] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0034] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0035] The following describes in detail a specific solution of a non-fixed load precision removal method based on load control fairness and effectiveness considerations provided by the present invention with reference to the accompanying drawings.

[0036] Refer to the attached Figure 1 , which shows a flow chart of a non-fixed load precise removal method based on load control fairness and effectiveness considerations provided by an embodiment of the present invention, the method comprising the following steps:

[0037] S1. The power grid is divided into regions based on physical topology. Each region is managed and controlled by a substation, while the master station is responsible for coordinated control between regions. The system frequency is collected, the frequency change rate is calculated, and the system frequency and frequency change rate are monitored to determine whether to send a "prepare to shed load" command to all substations.

[0038] The power grid is divided into: Each area is managed and controlled by a substation (such as a regional substation intelligent control unit equipped with a SCADA system). The substation collects the load of each load line in the area, and the substation presets the priority weight of the load line according to the grid user profile and priority power supply agreement. The main station (such as a provincial grid dispatching center, running an EMS energy management system) is responsible for inter-regional coordination and control, and collects grid system frequency from key nodes (such as the 220kV bus of the main substation) at a sampling frequency of 100Hz through a synchronized phasor measurement unit (PMU). (Unit: Hz), and calculate the frequency change rate The frequency change rate (unit: Hz / s) quantifies the speed at which the power grid system frequency decreases or increases, reflecting the severity of dynamic instability. The master station also collects the total load of each region (unit: MW) and presets regional priority weights based on regional load characteristics (such as the proportion of critical loads and user types). The master station and substations are connected via a fiber optic network (bandwidth ≥ 100Mbps) or a 5G network, with data transmission latency controlled within 10ms to ensure real-time interaction.

[0039] Set frequency thresholds based on grid system frequency and frequency change rate and frequency change rate threshold , compare the grid system frequency with the frequency threshold, compare the frequency change rate with the frequency change rate threshold, and determine whether to send a "prepare to shed load" instruction to all substations. If the grid system frequency is lower than the frequency threshold, that is, , or the absolute value of the frequency change rate exceeds the frequency change rate threshold, that is, , the master station considers that the frequency stability of the power grid system is threatened and immediately sends a "prepare to shed load" instruction to all substations via optical fiber or 5G network transmission, entering the load shedding amount calculation phase. If any of the conditions are not met, the master station continues to monitor the power grid system frequency and frequency change rate to maintain real-time response capabilities; the frequency threshold and frequency change rate threshold are preset by the master station based on the scale of the power grid, the proportion of new energy and historical operating data;

[0040] By real-time monitoring of the power grid system frequency and frequency change rate, it can quickly detect frequency instability caused by renewable energy output fluctuations or emergencies, providing data support and triggering basis for subsequent precise load shedding;

[0041] S2. Following the "prepare to shed load" instruction, the load shedding calculation phase begins. Based on the master station's real-time monitoring of the grid system frequency and frequency change rate, combined with preset regional priority weights, a dynamic weighted load precision shedding algorithm is used to calculate the load shedding required for each region. The maximum load shedding amount is preset, and the total load shedding amount is calculated, imposing a total amount constraint.

[0042] Following the "prepare to shed load" instruction, the load shedding calculation phase begins. Based on the master station's real-time monitoring of the grid system frequency and frequency change rate, combined with the preset regional priority weights, a dynamic weighted load precision shedding algorithm is used to calculate the load shedding required for each region. The specific implementation process is as follows:

[0043] By calculating the frequency deviation between the current grid system frequency and the rated frequency, the degree of static instability of the grid system is reflected, that is, the severity of the frequency deviation from the normal operating state. The larger the frequency deviation, the more serious the grid system imbalance, and the more load shedding is required to restore balance. Furthermore, the frequency deviation is divided by the deviation threshold set according to expert experience for standardization processing.

[0044] Dividing the absolute value of the frequency change rate by the frequency change rate threshold reflects the urgency of the dynamic instability of the power grid system, that is, the speed of frequency drop. The larger the frequency change rate, the faster the power grid system imbalance occurs, and a faster load shedding response is required.

[0045] By taking a weighted sum of the frequency deviation and the frequency change rate, the effects of static and dynamic instability are combined to reflect the overall severity of the imbalance in the power grid system. At the same time, the selection of the weighting coefficient is optimized through power grid simulation to ensure the balance between static and dynamic factors.

[0046] Furthermore, each area applies Function priority adjustment, The core of the function is to map the regional priority weight to a value between 0 and 1, using The nonlinear characteristics of the function ensure that the amount of resection in high-priority areas (such as hospitals) is sharply reduced, while the amount of resection in low-priority areas (such as industry) is smoothly distributed, avoiding the extreme distribution that may be caused by linear weighting, such as no resection in high-priority areas or full resection in low-priority areas;

[0047] area The formula for calculating the amount of load that needs to be removed is:

[0048] ,

[0049] in, Indicates area The amount of load that needs to be removed; Indicates area The current total load is used as the basis for the resection volume; The weighted coefficient of the frequency deviation term reflects the weight of the impact of static instability on the load removed. It is used to balance the contribution of frequency deviation and frequency change rate in the calculation of the load removed, satisfying , determined through power grid simulation optimization, with a value range of ; It represents the frequency deviation term, which is the ratio of the frequency deviation to the deviation threshold and is used to quantify the degree of static instability; Indicates the frequency deviation between the current grid system frequency and the rated frequency; Indicates the deviation threshold, which is set according to expert experience; The weighted coefficient of the frequency change rate term reflects the urgency of dynamic instability and is determined through power grid simulation optimization. The value range is ; It represents the frequency change rate term, which is the ratio of the absolute value of the frequency change rate to the frequency change rate threshold, and is used to quantify the degree of dynamic instability; It represents the weighted instability factor, which is the weighted sum of the frequency deviation and the frequency change rate, and combines static instability and dynamic instability; Indicates the priority adjustment factor, the value range is ; Represents the steepness parameter, which is used to control The steepness of the function affects the sensitivity of priority regulation. Through power grid simulation optimization, the value range is ; Indicates area Priority weight, reflecting the importance of the region, the value range ;

[0050] The frequency deviation and frequency change rate in the above formula provide the quantification and urgency of the imbalance, and the regional priority weight and The function ensures fairness, and the weighted coefficient balances the response speed and accuracy. It combines the current total load, weighted instability factor and priority adjustment factor. Based on the total load of the region, the removal ratio is determined according to the severity of the grid imbalance. At the same time, fair distribution is achieved through priority adjustment, and the region is finally accurately calculated. The load shedding amount needs to be determined while taking into account both grid stability and socioeconomic impact. The dynamic weighted load shedding algorithm addresses the shortcomings of traditional methods in terms of fairness (mis-shedding critical loads) and effectiveness (insufficient or excessive shedding) through nonlinear priority adjustment and a dynamic weighting mechanism.

[0051] At the same time, the master station presets the maximum load removal amount based on the total load of the power grid and the safety margin, calculates the total load removal amount, and imposes a total amount constraint:

[0052] ,

[0053] in, It represents the sum of the loads that need to be removed in all areas, that is, the total load removed; Indicates the number of regions; Indicates the maximum load that can be removed. It is set as the upper limit of the load removal to ensure the safety margin of the power grid. It is preset by the master station based on the total load of the power grid and the safety margin.

[0054] S3. Based on the load shedding required in each area, the substation optimizes the load shedding combination within the area. After optimization, the substation executes the shedding. The master station monitors the grid system frequency and frequency change rate after shedding to determine whether the blocking conditions are met to stop further shedding.

[0055] The master station distributes the calculated load shedding amount for each region to the corresponding regional substation. The substation further optimizes the shedding combination of specific load lines within the region to meet the allocated load shedding amount, while giving priority to protecting high-priority load lines to reduce social and economic impacts.

[0056] Specifically, for multiple load lines within the area, the substation selects the load lines to be removed using an existing linear programming algorithm. The goal is to minimize the impact of removing high-priority load lines while ensuring that the total amount of load removed accurately matches the load amount required to be removed assigned by the master station. The optimization formula is as follows:

[0057] ,

[0058] in, Represents the minimization objective, that is, the objective function of linear programming, and finds the solution that minimizes the objective function; Indicates the area The weighted removal amounts of all load lines in the system are summed up; Indicates area Total number of load lines within; Indicates area Neidi The priority weight of each load line; Represents the load line removal decision variable, which is a binary variable and represents the load line Whether it was removed, , 1 for resection, 0 for preservation; Indicates area Neidi The amount of load that needs to be removed from the load line;

[0059] During the optimization process, the substation ensures that the load shedding is precisely equal to the assigned load shedding amount, and that the shedding amount of each load line does not exceed the current load of the load line, as a constraint. A linear programming algorithm iteratively solves the problem to find the optimal load line combination that meets the constraints. After optimization is complete, the substation executes shedding using an intelligent circuit breaker or distribution automation switch, with an operating time of less than 100 milliseconds to quickly respond to frequency drops.

[0060] Furthermore, the master station continuously monitors the power system frequency and frequency change rate after the shedding to determine whether the blocking conditions are met to stop further shedding;

[0061] The locking conditions include two aspects: one is that the frequency of the power grid system reaches or exceeds the frequency threshold, indicating that the frequency of the power grid system is close to normal; the other is that the absolute value of the frequency change rate is less than the frequency change rate threshold, indicating that the dynamic instability has been alleviated. If both conditions are met at the same time, the master station sends a "stop removal" instruction to all substations through the optical fiber network to suspend further actions. If any condition is not met, it means that the power grid system frequency has not yet stabilized, and the load that needs to be removed in each area is recalculated and a new round of removal is started.

[0062] In summary, a non-fixed load precise removal method based on the fairness and effectiveness of load control was completed.

[0063] The order in which the embodiments of the invention are presented is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0064] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A non-fixed load precise removal method based on load control fairness and effectiveness considerations, characterized by: The following steps are involved: S1. The power grid is divided into regions based on physical topology. Each region is managed and controlled by a substation, while the master station coordinates and controls the load between regions. The system frequency is collected, the frequency change rate is calculated, and the system frequency and frequency change rate are monitored to determine whether to send a "prepare to shed load" command to all substations. S2. Following the "Prepare to Shed Load" command, the load shedding calculation phase begins. Based on the master station's real-time monitoring of the grid system frequency and frequency change rate, combined with preset regional priority weights, a dynamic weighted load shedding algorithm is used to calculate the load required for each region. Preset the maximum load removal amount, calculate the total load removal amount, and impose total amount constraints; In the implementation of the dynamic weighted load precise shedding algorithm, the current total load, the weighted sum of the frequency deviation and the frequency change rate, and the priority adjustment factor are combined to obtain the load that needs to be shedding in each area; area The formula for calculating the amount of load that needs to be removed is: ， in, Indicates area The amount of load that needs to be removed; Indicates area The current total load; Represents the weighting coefficient of the frequency deviation term; Indicates the frequency deviation between the current grid system frequency and the rated frequency; represents the deviation threshold; Represents the weighting coefficient of the frequency change rate term; represents the frequency change rate term; Indicates the frequency change rate threshold; represents the steepness parameter; Indicates area Priority weight; S3. Based on the load shedding required in each area, the substation optimizes the load shedding combination within the area. After optimization, the substation executes shedding. The master station monitors the grid system frequency and frequency change rate after shedding to determine whether the blocking conditions are met to stop further shedding.

2. The non-fixed load precise removal method based on load control fairness and effectiveness considerations according to claim 1 is characterized in that: Said S1 specifically includes: The load of each load line in the area is collected through the substation, and the substation presets the load line priority weight according to the grid user profile and priority power supply agreement; the total load of each area is collected through the main station, and the main station presets the regional priority weight according to the regional load characteristics.

3. The non-fixed load precise removal method based on load control fairness and effectiveness considerations according to claim 1 is characterized in that: Said S1 specifically includes: Based on the grid system frequency and frequency change rate, set the frequency threshold and frequency change rate threshold. Compare the grid system frequency with the frequency threshold, and compare the frequency change rate with the frequency change rate threshold to determine whether to send a "prepare to shed load" command to all substations.

4. The non-fixed load precise removal method based on load control fairness and effectiveness considerations according to claim 3 is characterized in that: Said S1 specifically includes: When the grid system frequency falls below the frequency threshold and the absolute value of the frequency change rate exceeds the frequency change rate threshold, the master station deems the grid system frequency stability threatened and immediately sends a "prepare for load shedding" command to all substations, entering the load shedding amount calculation phase. If neither condition is met, the master station continues to monitor the grid system frequency and frequency change rate.

5. The non-fixed load precise removal method based on load control fairness and effectiveness considerations according to claim 1 is characterized in that: Said S2 specifically includes: In the implementation process of the dynamic weighted load precise removal algorithm, the frequency deviation between the current power grid system frequency and the rated frequency is calculated, and the frequency deviation is divided by the deviation threshold for normalization; at the same time, the absolute value of the frequency change rate is divided by the frequency change rate threshold to reflect the urgency of dynamic instability of the power grid system.

6. The non-fixed load precise removal method based on load control fairness and effectiveness considerations according to claim 1 is characterized in that: Said S2 specifically includes: In the implementation process of the dynamic weighted load precise removal algorithm, the frequency deviation and the frequency change rate are weighted and summed as the weighted instability factor to comprehensively consider the influence of static instability and dynamic instability, and a priority adjustment factor is introduced to adjust the priority of each area.

7. The non-fixed load precise removal method based on load control fairness and effectiveness considerations according to claim 1 is characterized in that: Said S3 specifically includes: The master station distributes the calculated load shedding amount for each region to the corresponding regional substation, which then optimizes the load shedding combination within the region. During the optimization process, the substation ensures that the load shedding amount is equal to the allocated load shedding amount, and that the shedding amount of each load line does not exceed the current load of the load line. The optimal load line combination is found through iterative solution.

8. The non-fixed load precise shedding method based on load control fairness and effectiveness considerations according to claim 1 is characterized in that: Said S3 specifically includes: The blocking conditions include two aspects: one is that the grid system frequency reaches or exceeds the frequency threshold; the other is that the absolute value of the frequency change rate is less than the frequency change rate threshold. When both blocking conditions are met, the master station sends a "stop shedding" command to all substations via the optical fiber network. If either condition is not met, the load shedding amount required for each area is recalculated and a new round of shedding is initiated.

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