Method, system and equipment for evaluating stable operation capability of isolated network of regional power grid and medium

Abstract

The invention discloses a method, a system, equipment and a medium for evaluating stable operation capability of an isolated network of a regional power grid. The method comprises the following steps: acquiring related data of an isolated network system; based on related data of the isolated network system, initial equivalent inertia and initial power deviation are obtained through calculation; based on the frequency deviation value of the isolated network system, operating equipment of the isolated network system is adjusted, and equivalent inertia and power deviation are calculated and updated; calculating a disturbance frequency change rate according to the equivalent inertia and the power deviation; and judging a corresponding relation between the power deviation and the disturbance frequency change rate, and obtaining an evaluation result of the stable operation capability of the isolated network system. According to the isolated network stability quantitative evaluation method constructed based on the frequency change rate, only two core parameters of the system inertia and the new energy proportion are needed, complex modeling and time-consuming simulation are not needed, and the evaluation efficiency is improved through a dynamic parameter updating mechanism of high-frequency generator tripping and low-frequency load shedding in combination with a simplified frequency response model; whether the isolated network is endangered to collapse is determined in real time, and an emergency control decision basis is provided for power grid personnel.

Description

Technical Field

[0001] This invention relates to the field of power grid assessment technology, and in particular to a method, system, equipment and medium for assessing the stable operation capability of isolated regional power grids. Background Technology

[0002] The output of clean energy sources such as wind, solar, and small hydropower has reached over 80%. Grids with such a high proportion of clean energy face unique challenges during operation, especially when the system is passively placed into islanded operation due to emergencies such as tie-line faults or tie-line transformer tripping. Islanded operation means the grid is disconnected from the main grid and independently undertakes power balancing tasks. The high proportion of renewable energy integration significantly reduces the system's rotational inertia, making the grid more sensitive to fluctuations in key operating parameters such as frequency and voltage. Therefore, targeted stability assessment technologies are urgently needed to support the safe operation of the grid.

[0003] Existing technologies exhibit significant shortcomings in assessing the stability of isolated power grids in regions with a high proportion of renewable energy sources. On one hand, traditional assessment methods rely on complex time-domain simulations and multi-parameter modeling, consuming substantial computational resources and time, making them unsuitable for real-time assessments in isolated grid scenarios. On the other hand, existing technologies lack clear quantitative analysis methods for the dynamic response characteristics of the power grid under different power source proportions and disturbance types, failing to accurately identify key factors affecting isolated grid stability. Furthermore, when severe frequency fluctuations occur in the isolated grid, existing technologies fail to effectively integrate the dynamic impact of emergency control measures such as high-frequency generator tripping and low-frequency load shedding, leading to discrepancies between assessment results and actual operating conditions, making it difficult to reliably predict the risk of isolated grid system collapse. Therefore, there is an urgent need to develop an efficient, accurate, and adaptable quantitative assessment method for the stable operation capability of isolated grids with high renewable energy characteristics. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a method for assessing the stable operation capability of isolated regional power grids to address the problems of unclear dynamic response characteristics, low assessment efficiency, and inability to accurately determine stability in real time when isolated power grids in regions with a high proportion of renewable energy are in operation.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a method for assessing the stable operation capability of an isolated regional power grid, comprising:

[0008] Obtain relevant data from the isolated network system;

[0009] Based on the relevant data of the isolated network system, the initial equivalent inertia and initial power deviation are calculated and obtained.

[0010] Based on the frequency deviation value of the isolated network system, adjust the operating equipment of the isolated network system and calculate and update the equivalent inertia and power deviation;

[0011] The rate of change of the disturbance frequency is calculated based on the equivalent inertia and power deviation.

[0012] Determine the correspondence between the power deviation and the rate of change of the disturbance frequency to obtain the evaluation result of the stable operation capability of the isolated grid system.

[0013] As a preferred embodiment of the method for assessing the stable operation capability of isolated regional power grids according to the present invention, the method includes: calculating and obtaining the equivalent inertia and initial power deviation based on relevant data of the isolated grid system, including:

[0014] The relevant parameters of the generating units and the parameters of the new energy sources in the isolated grid system are input into the equivalent inertia calculation model to calculate and obtain the equivalent inertia;

[0015] The initial power deviation is calculated based on the total power output and load data of the isolated grid system.

[0016] The beneficial effects of this preferred technical solution are as follows: by inputting data such as unit parameters and the proportion of new energy into the equivalent inertia calculation model, the impact of system inertia on the frequency response of the isolated grid is quantified, avoiding the ambiguity of traditional methods that rely on empirical parameters; based on the real-time data of power output and load, the initial power deviation is calculated, and a benchmark value for the power balance of the isolated grid is established, providing an accurate starting point for subsequent dynamic evaluation and improving the credibility and repeatability of the evaluation results.

[0017] As a preferred embodiment of the method for assessing the stable operation capability of isolated power grids according to the present invention, the method includes: adjusting the operating equipment of the isolated power grid system and calculating and updating the equivalent inertia and power deviation based on the frequency deviation value of the isolated power grid system, including:

[0018] If the peak value of the positive frequency deviation is greater than the first threshold, it is determined to be over-frequency, all new energy equipment and units are disconnected, and the equivalent inertia and power deviation are calculated and updated.

[0019] If the peak value of the negative frequency deviation is greater than the second threshold, it is determined to be low frequency, the load is cut off, and the updated power deviation is calculated.

[0020] The beneficial effects of this preferred technical solution are as follows: setting a clear frequency deviation threshold to trigger tripping or load reduction actions standardizes the emergency control strategy in islanded grid operation, avoiding the lag and uncertainty of manual intervention; by updating the equivalent inertia and power deviation in real time, it dynamically reflects the impact of equipment adjustments on system inertia and power balance, enabling the evaluation model to track changes in the islanded grid operation status, solving the defect of static evaluation in existing technologies that cannot adapt to dynamic disturbances, and improving the timeliness and accuracy of the evaluation.

[0021] As a preferred embodiment of the method for assessing the stable operation capability of isolated regional power grids according to the present invention, the method for determining the correspondence between the power deviation and the rate of change of disturbance frequency to obtain the assessment result of the stable operation capability of the isolated grid system includes:

[0022] Determine whether the power deviation and disturbance frequency change rate corresponding to different evaluation indicators are within the set threshold;

[0023] If the rate of change of the disturbance frequency is less than the third threshold range, and the total output of the unit is greater than the load or the absolute value of the initial power deficit minus the total low-frequency load reduction is less than the regional spinning reserve, then the islanded grid system is determined to be stable.

[0024] If the rate of change of the disturbance frequency is greater than the third threshold range, or if the absolute value of the initial power deficit minus the total low-frequency load reduction is greater than or equal to the regional spinning reserve, the islanded system is determined to be unstable.

[0025] The beneficial effects of this preferred technical solution are as follows: Based on the preset frequency change rate threshold range and power balance verification rules, a multi-dimensional stability judgment logic is constructed to avoid misjudgment by a single indicator; the complex system stability assessment is transformed into threshold comparison and simple arithmetic comparison, which greatly reduces the computational complexity; by distinguishing between the two causes of instability, namely, excessive frequency change rate and power imbalance, differentiated fault handling strategies are provided for operators, thereby improving the pertinence and effectiveness of power grid emergency response.

[0026] As a preferred embodiment of the method for assessing the stable operation capability of isolated grids in the region described in this invention, the assessment indicators include the frequency control target of the isolated grid system, the frequency protection action of new energy sources, high-frequency action, and low-frequency action.

[0027] As a preferred embodiment of the method for assessing the stable operation capability of isolated regional power grids described in this invention, the calculation formulas for calculating the updated equivalent inertia and power deviation are expressed as follows:

[0028]

[0029] ΔP d ′=ΔP d -ΔP c

[0030] ΔP d ′=ΔP d +ΔP L

[0031] Among them, H′ s For the updated equivalent inertia, H si S is the per-unit value of the inertia for each traditional generator unit. Bi Where η is the rated capacity of each unit, H is the proportion of renewable energy, and η is the percentage of renewable energy. sj S cjΔP′ represents the inertia and rated capacity of each unit that was disconnected. d For the updated power deviation, ΔP d Initial power deficit, with the direction of islanded grid transmission as positive, ΔP c For the active power output of the disconnected unit, ΔP L The sum of the capacities of the loads that were removed.

[0032] As a preferred embodiment of the method for assessing the stable operation capability of isolated regional power grids described in this invention, the formula for calculating the disturbance frequency change rate is expressed as:

[0033]

[0034] Where RoCoFmax is the rate of change of the perturbation frequency, ΔP′ d For the updated power deviation, H′ s The updated equivalent inertia is given by f0, where f0 is the rated power.

[0035] Secondly, the present invention provides a regional power grid isolated grid stability operation capability assessment system, including: a data acquisition module, used to acquire relevant data of the isolated grid system;

[0036] A primary calculation module is used to calculate and obtain the initial equivalent inertia and initial power deviation based on the relevant data of the isolated network system;

[0037] The update module is used to adjust the operating equipment of the isolated network system and calculate and update the equivalent inertia and power deviation based on the frequency deviation value of the isolated network system.

[0038] The secondary calculation module is used to calculate and obtain the rate of change of the disturbance frequency based on the power deviation.

[0039] The evaluation module is used to determine the correspondence between the power deviation and the rate of change of the disturbance frequency, and to obtain the evaluation results of the stable operation capability of the isolated grid system.

[0040] Thirdly, the present invention provides an electronic device, comprising:

[0041] Memory and processor;

[0042] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the method for assessing the stable operation capability of isolated regional power grids are implemented.

[0043] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the method for assessing the stable operation capability of the regional power grid in isolated grids.

[0044] Compared with existing technologies, the advantages of this invention are as follows: This invention constructs a quantitative assessment method for isolated grid stability based on the frequency change rate. It requires only two core parameters: system inertia and the proportion of renewable energy. Through an equivalent inertia calculation model and a table showing the correspondence between the frequency change rate and deviation, it achieves rapid threshold-based assessment of isolated grid stability. This invention eliminates the need for complex modeling and time-consuming simulations. Through a dynamic parameter update mechanism involving high-frequency generator tripping and low-frequency load shedding, combined with a simplified frequency response model, it improves assessment efficiency, enabling real-time identification of whether an isolated grid is on the verge of collapse, and providing grid operators with precise emergency control decision-making support. Attached Figure Description

[0045] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the overall process of the method for assessing the stable operation capability of isolated regional power grids according to an embodiment of the present invention.

[0047] Figure 2 This is a schematic diagram of the isolated grid frequency deviation calculation model of the method for assessing the stable operation capability of isolated grids in a regional power grid according to an embodiment of the present invention. Detailed Implementation

[0048] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0049] Example 1, referring to Figure 1 As an embodiment of the present invention, a method for assessing the stable operation capability of an isolated regional power grid is provided, comprising:

[0050] S100: Acquire relevant data for the isolated network system; based on the isolated network system data, calculate and obtain the initial equivalent inertia and initial power deviation;

[0051] S102: Based on the frequency deviation value of the isolated network system, adjust the operating equipment of the isolated network system and calculate and update the equivalent inertia and power deviation;

[0052] S104: Calculate and obtain the rate of change of the disturbance frequency based on the equivalent inertia and power deviation;

[0053] S106: Determine the correspondence between power deviation and disturbance frequency change rate to obtain the evaluation results of the stable operation capability of the isolated grid system.

[0054] It should be noted that this invention acquires relevant data of the isolated grid system, calculates initial parameters based on the equivalent inertia model and power balance formula, providing a quantitative benchmark for evaluation and solving the ambiguity problem of traditional methods relying on experience. Then, it triggers tripping or load shedding actions based on frequency deviation, dynamically updating system inertia and power deviation to reflect changes in the isolated grid's operating status in real time, avoiding the lag of static evaluation. Furthermore, it calculates the disturbance frequency change rate using a simplified formula, transforming the complex frequency response into a quantifiable characteristic indicator. Stability is comprehensively judged by comparing preset thresholds and power balance conditions, achieving full automation from data acquisition to result output. This method requires only two core parameters: system inertia and the proportion of renewable energy. Through a logical chain of data-driven modeling, dynamic parameter updates, and threshold comparison evaluation, it provides an efficient and accurate real-time means of judging the stability of isolated grids with a high proportion of renewable energy, reducing the risk of power accident events.

[0055] Example 2, refer to Figures 1-2 Table 1 and the above embodiment are examples of the present invention. Based on the above embodiment, a method for evaluating the stable operation capability of isolated regional power grids is provided.

[0056] In this embodiment of the invention, the data related to the isolated grid system in step S100 includes the per-unit inertia value, rated capacity, droop coefficient of traditional units, the proportion of new energy output, total power output data, load data, and real-time frequency monitoring data, etc.

[0057] In one optional implementation, after obtaining the relevant data of the isolated network system, the data is preprocessed. The preprocessing includes data format standardization and outlier removal, converting parameters such as inertia and capacity of different units into per-unit values, removing jump values ​​caused by sensor failures in the frequency monitoring data, and ensuring that the data input to the model meets the per-unit calculation requirements and is true and valid.

[0058] In this embodiment of the invention, the relevant parameters of the generator units and the parameters of the new energy sources in the isolated grid system are input into the equivalent inertia calculation model to calculate and obtain the equivalent inertia;

[0059] For example, the equivalent inertia H S Represented as:

[0060]

[0061] Among them, H si S is the per-unit value of the inertia for each traditional generator unit. Bi η represents the rated capacity of each unit, and η represents the proportion of renewable energy.

[0062] In this embodiment of the invention, the initial power deviation is calculated based on the total power output data and load data of the isolated grid system.

[0063] It should be noted that by inputting data such as unit parameters and the proportion of renewable energy into the equivalent inertia calculation model, the impact of system inertia on the frequency response of the isolated grid is quantified, avoiding the ambiguity of relying on empirical parameters in traditional methods. The initial power deviation is calculated based on real-time data of power output and load, and a benchmark value for the power balance of the isolated grid is established, providing an accurate starting point for subsequent dynamic evaluation and improving the credibility and repeatability of the evaluation results.

[0064] In this embodiment of the invention, step S102, which involves adjusting the operating equipment of the isolated network system based on the frequency deviation value and calculating and updating the equivalent inertia and power deviation, further includes sub-steps A1-A2:

[0065] A1: If the peak value of the positive frequency deviation is greater than the first threshold, it is determined to be over-frequency. All new energy equipment and units are disconnected, and the equivalent inertia and power deviation are calculated and updated.

[0066] A2: If the peak value of the negative frequency deviation is greater than the second threshold, it is determined to be low frequency, the load is cut off, and the updated power deviation is calculated.

[0067] In this embodiment of the invention, the calculation formulas for calculating the updated equivalent inertia and power deviation are expressed as follows:

[0068]

[0069] ΔP d ′=ΔP d -ΔP c

[0070] ΔP d ′=ΔP d +ΔP L

[0071] Among them, H′ s For the updated equivalent inertia, H si S is the per-unit value of the inertia for each traditional generator unit. Bi Where η is the rated capacity of each unit, H is the proportion of renewable energy, and η is the percentage of renewable energy. sj S cj ΔP′ represents the inertia and rated capacity of each unit that was disconnected. d For the updated power deviation, ΔP d Initial power deficit, with the direction of islanded grid transmission as positive, ΔP c The active power output of the disconnected unit.

[0072] In this embodiment of the invention, the frequency deviation value of the isolated network system is obtained through an isolated network frequency deviation calculation model, as shown in the following example: Figure 2 As shown, Figure 2 In, H′ s For the updated equivalent inertia, T R η is the frequency regulation response time constant, approximately taken as 12s (typical data); R is the droop coefficient of traditional units, taken as the minimum value of all units, R = 0.04; η is the proportion of renewable energy; ΔP′ d For the updated power deviation, ΔP m For power feedback; K L For the load feedback loop, K is approximated. L =1.8; Δf is the frequency deviation.

[0073] In one alternative implementation, the first threshold and the second threshold can be set to 5Hz and -2Hz, which correspond to the peak values ​​of the positive / negative frequency deviations of the isolated network stability boundary.

[0074] In one alternative implementation, the frequency deviation value of the isolated network system can be obtained by a real-time frequency monitoring device. High-precision frequency sensors, such as synchronous phasor measurement units, are deployed at key nodes in the isolated network to collect system frequency data at a millisecond-level sampling frequency, calculate the peak frequency deviation, and transmit it to the system.

[0075] In another alternative implementation, the frequency deviation value of the isolated grid system can be obtained through a state estimation model. Based on the active power output, real-time load data, and equivalent inertia model of each unit within the isolated grid, the value can be obtained using the formula: Estimate the frequency deviation and adjust the model parameters based on historical data.

[0076] It should be noted that this invention standardizes the emergency control strategy in isolated grid operation by setting a clear frequency deviation threshold to trigger tripping or load reduction actions, thus avoiding the lag and uncertainty of manual intervention. By updating the equivalent inertia and power deviation in real time, it dynamically reflects the impact of equipment adjustments on system inertia and power balance, enabling the evaluation model to track changes in the isolated grid operation status. This solves the problem that static evaluation in the prior art cannot adapt to dynamic disturbances, and improves the timeliness and accuracy of the evaluation.

[0077] In this embodiment of the invention, the calculation formula for obtaining the rate of change of the disturbance frequency based on the equivalent inertia and power deviation in step S104 is expressed as follows:

[0078]

[0079] Where RoCoFmax is the rate of change of the perturbation frequency, ΔP d ′ represents the updated power deviation, H s ′ represents the updated equivalent inertia, and f0 represents the rated power.

[0080] In this embodiment of the invention, the rated power f0 = 50Hz.

[0081] It should be noted that by combining the updated power deviation with the equivalent inertia using a formula, and taking the rated power f0 = 50Hz as a benchmark, a rapid calculation of the disturbance frequency change rate is achieved. This allows for real-time quantification of the frequency fluctuation rate of an islanded network system after control measures such as tripping and load reduction.

[0082] After adjusting for high-frequency generator switching and low-frequency load reduction, the rate of change of the most disturbed frequency decreased from the initial 5.94 Hz / s to 1.01 Hz / s, falling into the stable range [-1 Hz / s, 3 Hz / s], directly reflecting the transition of the isolated grid from instability to stability. This calculation method relies only on basic parameters such as system inertia and the proportion of renewable energy sources, without requiring complex modeling. Its evaluation efficiency is significantly improved compared to traditional methods, and the results highly match the actual operating state of the isolated grid. This effectively solves the problem of difficulty in quantifying dynamic response characteristics in existing technologies, providing accurate quantitative basis for real-time assessment of the stable operation capability of isolated grids.

[0083] In one alternative implementation, the disturbance frequency change rate can be obtained through real-time monitoring and calculation. Specifically, the frequency data of the isolated grid system is collected in real time using a synchronous phasor measurement unit, the frequency change per unit time is calculated, and the disturbance frequency change rate is directly output. Based on measured data, the accuracy can reach the millisecond level, which is suitable for power grid stability assessment scenarios with extremely high real-time requirements.

[0084] In another alternative implementation, the disturbance frequency change rate can be obtained by state-space model deduction. Specifically, a state-space model is established based on the dynamic equations of the power system. The updated equivalent inertia and power deviation are used as input parameters. The frequency change curve over time is deduced by numerical integration algorithms, such as the Euler method and the Runge-Kutta method, and then the maximum frequency change rate is calculated to simulate the entire frequency response process after the disturbance. This method is suitable for offline analysis or stability prediction of complex disturbance scenarios.

[0085] In this embodiment of the invention, step S106, which determines the correspondence between power deviation and disturbance frequency change rate to obtain the evaluation result of the stable operation capability of the isolated grid system, further includes sub-steps B1-B3:

[0086] B1: Determine whether the power deviation and disturbance frequency change rate corresponding to different evaluation indicators are within the set threshold;

[0087] B2: If the rate of change of the disturbance frequency is less than the third threshold range, and the total output of the unit is greater than the load or the absolute value of the initial power deficit minus the total low-frequency load reduction is less than the regional spinning reserve, then the islanded grid system is determined to be stable.

[0088] B3: If the rate of change of the disturbance frequency is greater than the third threshold range or the absolute value of the initial power deficit minus the total low-frequency load reduction is greater than or equal to the regional spinning reserve, the islanded system is determined to be unstable.

[0089] In this embodiment of the invention, the evaluation indicators include the frequency control target of the isolated grid system, the frequency protection action of new energy sources, high-frequency action, and low-frequency action.

[0090] Specifically, the corresponding rate of change of disturbance frequency according to different control target frequency deviations Δf is shown in Table 1.

[0091] Table 1 Correspondence between the rate of change of disturbance frequency and frequency deviation

[0092]

[0093] Specifically, the threshold values ​​are determined based on the correspondence between different evaluation indicators in Table 1. The threshold values ​​for the rate of change of disturbance frequency that the isolated network can maintain stability are [-1Hz / s, 3Hz / s], corresponding to the maximum frequency deviation [-2.5Hz, 5Hz]; the threshold values ​​for the isolated network frequency control target are [-1Hz / s, 2Hz / s], corresponding to the frequency deviation [-2Hz, 3Hz].

[0094] When the rate of change of the disturbance frequency falls within the stable threshold range, and the total output of the unit is greater than the load (positive power balance) or the absolute value of the initial power deficit minus the total low-frequency load reduction is less than the spinning reserve (power deficit can be dynamically compensated), the islanded grid is determined to be stable.

[0095] If the rate of change of the disturbance frequency exceeds the threshold range, or if the power deficit cannot be compensated for by load shedding and spinning reserve (i.e., the absolute value of the initial power deficit minus the total low-frequency load shedding is greater than the spinning reserve), then the islanded grid is determined to be unstable. This logic integrates the dynamic frequency response and the static power balance condition, achieving multi-dimensional and accurate determination of islanded grid stability.

[0096] In this embodiment of the invention, a frequency not greater than 55Hz and not less than 47.5Hz is used as the boundary for the stability of the isolated network frequency. The final rate of change of the disturbance frequency is calculated, and the range of [-1Hz / s, 3Hz / s] is checked according to Table 1. The corresponding maximum frequency deviation is [-2.5Hz, 5Hz], and the stability of the isolated network is determined.

[0097] In one alternative implementation, the stability of an isolated grid can be assessed using the high-frequency operation characteristic verification method for small hydropower plants. Since small hydropower units can still maintain operation and participate in primary frequency regulation under high-frequency conditions, if such units exist in the isolated grid and the total output is greater than the load, even if the disturbance frequency change rate briefly exceeds the upper limit threshold, it can still be determined that the isolated grid has short-term stability capability. Further evaluation is required in conjunction with subsequent frequency trends.

[0098] In another optional implementation, the stability of the isolated grid is determined by using the pre-evaluation method of the new energy protection action. By monitoring whether the rate of change of the disturbance frequency is close to the new energy frequency protection threshold of 0.5Hz / s or -2Hz / s, it is predicted whether a large-scale trip of new energy units will be triggered. When the rate of change of the disturbance frequency reaches 0.4Hz / s or is close to the 0.5Hz / s threshold of the new energy high-frequency protection, even if the current isolated grid frequency deviation does not exceed the limit, the tripping strategy should be adjusted in advance to avoid a chain reaction caused by a sudden drop in inertia due to the protection action.

[0099] It should be noted that due to the special characteristics of small hydropower units, they can still maintain operation at higher frequencies such as 70Hz and can operate at minimum power for a long time under the action of primary frequency regulation. Therefore, in this assessment, when the unit power is greater than the load, it is generally considered that the isolated grid can maintain stable operation. At the same time, if the absolute value of the initial power deficit ΔPd minus the total low-frequency load reduction is less than the rotating reserve in the region, it is directly considered that the isolated grid cannot operate stably.

[0100] Example 3, referring to Table 2, is an embodiment of the present invention. Based on the above embodiments, a method for evaluating the stable operation capability of isolated regional power grids is provided. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0101] Taking a typical operation mode of a regional power grid as an example, the effectiveness of the above quantitative evaluation method is verified:

[0102] The output, inertia, and power deviation of each unit in the isolated grid at each stage are shown in Table 2; the final system frequency disturbance change rate is 1.01 Hz / s, and the isolated grid system can operate stably.

[0103] Table 2 Calculation of Disturbance Frequency Change Rate at Each Stage of Isolated Network

[0104]

[0105] It should be noted that the frequency protection operation cut off 1 unit (20MW) of G12, 2 units (36MW) of G13, 22MW of G14, 30MW of W11, 20MW of W12 and 32MW of PV11, totaling 160MW; and shuffled 21MW of load (not considering special wheel operation).

[0106] As shown in Table 2, the power deviation of a certain power grid in each stage of isolated operation was analyzed using a quantitative evaluation method. In the initial state, the power deviation was 133MW and the disturbance frequency change rate was 5.94Hz / s. After triggering high-frequency generator tripping, the equivalent inertia decreased from 2.35s to 3.52s, the power deviation dropped to -7MW, and the frequency change rate turned to -0.51Hz / s, effectively suppressing the risk of overfrequency. After low-frequency load reduction adjustment, the final power deviation was 14MW and the disturbance frequency change rate was 1.01Hz / s, falling into the stable range [-1Hz / s, 3Hz / s]. Moreover, the total output of the units (98MW) was greater than the remaining load (84MW), and the isolated grid was determined to be stable. This process only requires basic parameters such as unit inertia and the proportion of renewable energy. By dynamically updating the equivalent inertia and power deviation, combined with threshold comparison, it achieves rapid determination of isolated grid stability. The evaluation efficiency is improved compared with traditional methods, and the results are consistent with actual operation. This verifies the effectiveness of the present invention in accurately and efficiently evaluating the stable operation capability of isolated grids in power grids with a high proportion of renewable energy, which can reduce the risk of power accident events.

[0107] Example 4 illustrates a schematic scheme for a method to assess the stable operation capability of an isolated regional power grid. It should be noted that the technical solution of the system for assessing the stable operation capability of an isolated regional power grid in this example is based on the same concept as the technical solution of the method described above. Details not described in detail in the technical solution of the system for assessing the stable operation capability of an isolated regional power grid in this example can be found in the description of the technical solution of the method described above.

[0108] This embodiment also provides a system for assessing the stable operation capability of isolated regional power grids, including:

[0109] The data acquisition module is used to acquire relevant data from the isolated network system.

[0110] The primary calculation module is used to calculate and obtain the initial equivalent inertia and initial power deviation based on relevant data of the isolated network system.

[0111] The update module is used to adjust the operating equipment of the isolated network system and calculate and update the equivalent inertia and power deviation based on the frequency deviation value of the isolated network system.

[0112] The secondary calculation module is used to calculate and obtain the rate of change of the disturbance frequency based on the power deviation.

[0113] The evaluation module is used to determine the correspondence between power deviation and disturbance frequency change rate, and to obtain the evaluation results of the stable operation capability of the isolated grid system.

[0114] This embodiment also provides an electronic device applicable to the assessment of the stable operation capability of isolated regional power grids, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the method for assessing the stable operation capability of isolated regional power grids as proposed in the above embodiment.

[0115] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the method for assessing the stable operation capability of isolated regional power grids as proposed in the above embodiments.

[0116] The storage medium proposed in this embodiment and the method for assessing the stable operation capability of isolated regional power grids proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0117] Based on the above description of the implementation methods, those skilled in the art will clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0118] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for assessing the stable operation capability of an isolated regional power grid, characterized in that, include: Obtain relevant data from the isolated network system; Based on the relevant data of the isolated network system, the initial equivalent inertia and initial power deviation are calculated and obtained. Based on the frequency deviation value of the isolated network system, adjust the operating equipment of the isolated network system and calculate and update the equivalent inertia and power deviation; The rate of change of the disturbance frequency is calculated based on the equivalent inertia and power deviation. Determine the correspondence between the power deviation and the rate of change of the disturbance frequency to obtain the evaluation result of the stable operation capability of the isolated grid system.

2. The method for assessing the stable operation capability of isolated regional power grids as described in claim 1, characterized in that, Based on the relevant data of the isolated network system, the equivalent inertia and initial power deviation are calculated and obtained, including: The relevant parameters of the generating units and the parameters of the new energy sources in the isolated grid system are input into the equivalent inertia calculation model to calculate and obtain the equivalent inertia; The initial power deviation is calculated based on the total power output and load data of the isolated grid system.

3. The method for assessing the stable operation capability of isolated regional power grids as described in claim 2, characterized in that, Based on the frequency deviation value of the isolated network system, adjust the operating equipment of the isolated network system and calculate and update the equivalent inertia and power deviation, including: If the peak value of the positive frequency deviation is greater than the first threshold, it is determined to be over-frequency, all new energy equipment and units are disconnected, and the equivalent inertia and power deviation are calculated and updated. If the peak value of the negative frequency deviation is greater than the second threshold, it is determined to be low frequency, the load is cut off, and the updated power deviation is calculated.

4. The method for assessing the stable operation capability of isolated regional power grids as described in claim 3, characterized in that, Determine the correspondence between the power deviation and the rate of change of the disturbance frequency to obtain the evaluation results of the stable operation capability of the isolated grid system, including: Determine whether the power deviation and disturbance frequency change rate corresponding to different evaluation indicators are within the set threshold; If the rate of change of the disturbance frequency is less than the third threshold range, and the total output of the unit is greater than the load or the absolute value of the initial power deficit minus the total low-frequency load reduction is less than the regional spinning reserve, then the islanded grid system is determined to be stable. If the rate of change of the disturbance frequency is greater than the third threshold range, or if the absolute value of the initial power deficit minus the total low-frequency load reduction is greater than or equal to the regional spinning reserve, the islanded system is determined to be unstable.

5. The method for assessing the stable operation capability of isolated regional power grids as described in claim 4, characterized in that, The evaluation indicators include the frequency control target of the isolated grid system, the frequency protection action of new energy sources, high-frequency action, and low-frequency action.

6. The method for assessing the stable operation capability of isolated regional power grids as described in claim 2, characterized in that, The formulas for calculating the updated equivalent inertia and power deviation are expressed as follows: ΔP d ′=ΔP d -ΔP c ΔP d ′=ΔP d +ΔP L Among them, H′ s For the updated equivalent inertia, H si S is the per-unit value of the inertia for each traditional generator unit. Bi Where η is the rated capacity of each unit, H is the proportion of renewable energy, and η is the percentage of renewable energy. sj S cj ΔP′ represents the inertia and rated capacity of each unit that was disconnected. d For the updated power deviation, ΔP d Initial power deficit, with the direction of islanded grid transmission as positive, ΔP c For the active power output of the disconnected unit, ΔP L The sum of the capacities of the loads that were removed.

7. The method for assessing the stable operation capability of isolated regional power grids as described in claim 5, characterized in that, The formula for calculating the rate of change of the disturbance frequency is as follows: Where RoCoFmax is the rate of change of the perturbation frequency, ΔP′ d For the updated power deviation, H′ s The updated equivalent inertia is given by f0, where f0 is the rated power.

8. A system for assessing the stable operation capability of an isolated regional power grid, comprising the method described in any one of claims 1-7, characterized in that, include: The data acquisition module is used to acquire relevant data from the isolated network system. A primary calculation module is used to calculate and obtain the initial equivalent inertia and initial power deviation based on the relevant data of the isolated network system; The update module is used to adjust the operating equipment of the isolated network system and calculate and update the equivalent inertia and power deviation based on the frequency deviation value of the isolated network system. The secondary calculation module is used to calculate and obtain the rate of change of the disturbance frequency based on the power deviation. The evaluation module is used to determine the correspondence between the power deviation and the rate of change of the disturbance frequency, and to obtain the evaluation results of the stable operation capability of the isolated grid system.

9. An electronic device, characterized in that, include: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the method for assessing the stable operation capability of isolated regional power grids as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores computer-executable instructions, which, when executed by a processor, implement the steps of the method for assessing the stable operation capability of isolated regional power grids as described in any one of claims 1 to 7.

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