A simulation evaluation method for new energy carrying capacity of a sending end power grid

Abstract

The application belongs to the technical field of new energy carrying capacity analysis, and specifically discloses a kind of sending end power grid new energy carrying capacity simulation evaluation method, comprising the following steps: S1, distributed new energy is equivalent to main grid according to access point, adjust power grid actual operation factor;S2, increase new energy output, increase rotating reserve capacity;S3, carry out fault checking, obtain checking result;S4, evaluate the constraint factors and new energy carrying capacity of current power grid typical operation mode;S5, re-adjust the actual operation factor of power grid, comparative analysis actual operation factor on the influence of new energy carrying capacity of whole network, evaluate new energy carrying capacity influencing factor and carrying capacity.This application fully excavates the new energy carrying capacity of power system from multiple angles, and accurately locates the key influencing factors restricting new energy carrying capacity.This application is suitable for sending end power grid new energy carrying capacity simulation evaluation.

Description

Technical Field

[0001] This invention belongs to the field of new energy carrying capacity analysis technology, specifically a simulation evaluation method for the new energy carrying capacity of the sending-end power grid. Background Technology

[0002] The large-scale integration of new energy sources has given the sending-end power grid the characteristics of "high proportion of new energy and high proportion of power electronic equipment" on the outside, and "low immunity, low inertia and low short-circuit capacity" on the inside. This will pose a huge challenge to the power system's support capacity, balance capacity, regulation capacity and safety and stability.

[0003] Therefore, it is particularly important to thoroughly explore the factors affecting the renewable energy carrying capacity of the sending-end power grid and to assess the renewable energy carrying capacity of the sending-end power grid. This is of great significance for the future planning and development of the power grid and for avoiding the problems of wind and solar power curtailment and the occurrence of power stagnation.

[0004] Currently, research on renewable energy carrying capacity largely focuses on the receiving-end power grid, and the influencing factors are not comprehensive enough. For example, some methods consider the impact of peak-shaving and security / stability constraints to set a renewable energy carrying capacity ceiling for the East China receiving-end power grid; others analyze the impact of factors such as load, peak-shaving capacity, and reserve ratio to propose renewable energy absorption coefficients and renewable energy carrying capacity coefficients to reflect the renewable energy carrying capacity of the power system; still others establish linear optimal power flow models for renewable energy carrying capacity, considering node voltage, line power flow, power backflow, and generator ramping constraints to evaluate the renewable energy carrying capacity of the power system. However, these studies focus on the receiving-end power grid or analyze renewable energy carrying capacity from one or a few influencing factors, lacking a comprehensive consideration of real-time operational factors such as traditional generator unit operating levels, peak-shaving capacity (spinning reserve capacity), load levels, cross-sectional power flow, renewable energy absorption priorities, as well as grid security / stability constraints and power balance constraints. Therefore, they are insufficient to accurately reflect the renewable energy carrying capacity of the power grid.

[0005] In conclusion, it is necessary to invent a method that can accurately assess the renewable energy carrying capacity of the sending-end power grid, analyze the key factors affecting the renewable energy carrying capacity of the sending-end power grid, and provide a theoretical basis for the rational planning and development of large sending-end power grids and the determination of the commissioning sequence and spatial location of renewable energy. Summary of the Invention

[0006] The purpose of this invention is to provide a simulation evaluation method for the renewable energy carrying capacity of the sending-end power grid, so as to analyze the key factors affecting the renewable energy carrying capacity of the sending-end power grid, and provide a theoretical basis for the rational planning and development of large sending-end power grids and the determination of the commissioning sequence and spatial location of renewable energy.

[0007] To achieve the above objectives, the present invention employs the following technical methods:

[0008] A simulation evaluation method for the renewable energy carrying capacity of a sending-end power grid, based on factors influencing renewable energy carrying capacity, including safety and stability constraints, power balance constraints, and actual grid operation factors, comprises the following steps:

[0009] S1. Equip the distributed new energy sources connected to the distribution network in the sending-end power grid / system to the main grid according to the access point, and adjust the actual operation factors of the power grid according to the typical operation mode that occurs in the actual operation of the power grid.

[0010] S2. Increase the output of new energy sources, and at the same time reduce the output of traditional generator sets according to the actual peak-shaving capacity of traditional generator sets, increase the spinning reserve capacity of the sending-end grid / system, and make room for the transmission of new energy sources until the grid reaches the static safety constraint boundary.

[0011] S3. Perform static analysis of N-1 fault, dynamic safety and stability verification of N-1 and N-2 faults. The verification of N-2 fault needs to consider the machine switching strategy of the safety and stability control system, and obtain the verification results.

[0012] S4. Based on the verification results, assess the limiting factors and scale of new energy carrying capacity under the current typical power grid operation mode;

[0013] S5. Return to step S1, readjust the actual operating factors of the power grid to make the power grid operate under another typical operating mode, and proceed to steps S2-S4 to compare and analyze the impact of the actual operating factors on the new energy carrying capacity of the entire power grid, and evaluate the influencing factors and carrying capacity scale of the new energy carrying capacity under the current typical operating mode of the power grid.

[0014] As a limitation: In step S1, the distributed new energy connected to the distribution network is connected to the main network at the same access point as the main network. Specifically, after the new energy model of the same capacity is used for equivalence processing, the new energy is connected to the main network according to the power source nature.

[0015] As a limitation: the static safety constraint boundary includes the following: the increase in new energy output causing the voltage of the hub station to reach the lower limit of the operating voltage curve; the power transmission from the new energy gathering area causing the main transformer to reach the thermal stability limit; the key lines and sections of the power transmission channel reaching the stability control limit; and the power balance limitation caused by insufficient peak-shaving capacity of traditional generator sets or the control of key sections reaching the limit value. In step S2, the output of new energy is increased, and at the same time, the output of traditional generator sets is reduced according to the actual peak-shaving capacity of traditional generator sets, and the spinning reserve capacity of the sending-end grid / system is increased to make room for the transmission of new energy, until the grid reaches at least one of the static safety constraint boundaries.

[0016] As a limitation: In step S4, the constraints on the carrying capacity of new energy sources and the scale of new energy carrying capacity are evaluated based on the verification results. Specifically, if the verification results meet the safety and stability constraints, the constraint on the carrying capacity of new energy sources under the current typical operating mode is determined to be the static safety constraint boundary reached in step S2, and the total output of new energy sources at this time is taken as the scale of new energy carrying capacity under the current typical operating mode of the power grid. If the verification results do not meet the safety and stability constraints, the output of new energy sources is reduced, and the power flow of the sending-end power grid / system is adjusted to be within the static safety constraint boundary. Then, the operation of step S3 is performed again until the verification results of step S3 meet the safety and stability constraints. Then, the final safety and stability constraints reached are determined to be the constraint on the carrying capacity of new energy sources, and the total output of new energy sources at this time is taken as the scale of new energy carrying capacity under the current typical operating mode of the power grid.

[0017] As a limitation: In step S5, the factors influencing the renewable energy carrying capacity and the carrying scale under the current typical power grid operation mode are evaluated as follows: If the verification result meets the safety and stability constraints, the renewable energy carrying capacity constraint under the current typical power grid operation mode is determined to be the static safety constraint boundary reached in step S2, and the total renewable energy output at this time is taken as the renewable energy carrying scale under the current typical power grid operation mode; if the verification result does not meet the safety and stability constraints, the renewable energy output is reduced, and the power flow of the sending-end power grid / system is adjusted to be within the static safety constraint boundary, and then the operation of step S3 is performed until the verification result of step S3 meets the safety and stability constraints, then the final safety and stability constraint reached is determined to be the constraint factor of renewable energy carrying capacity, and the total renewable energy output at this time is taken as the renewable energy carrying scale under the current typical power grid operation mode; if, during the adjustment of the actual power grid operation factors, due to power balance constraints, the typical operation mode fails to reach the static safety constraint boundary in step S2, and the verification result in step S3 also meets the safety and stability constraints, then the power balance constraint is determined to be the constraint factor of renewable energy carrying capacity, and the total renewable energy output at this time is taken as the renewable energy carrying scale under the current typical power grid operation mode.

[0018] As a limitation: safety and stability constraints include frequency stability constraints, static voltage safety constraints, transient stability constraints, dynamic stability constraints, thermal stability constraints, and new energy-related constraints;

[0019] Frequency stability constraint: After a large disturbance (N-2 / N-3 fault) occurs in the sending-end power grid system and the tripping strategy of the safety and stability control system is considered, the lowest frequency of the sending-end power grid system should not cause the grid to perform low-frequency load shedding. The lowest frequency that will not cause the grid to perform low-frequency load shedding is 49.25Hz.

[0020] Static voltage safety constraint: refers to the initial power flow voltage of hub stations of 500kV and above meeting the lower limit of the operating voltage curve, and the voltage of 500kV stations can be adjusted back to 500kV after an N-1 fault;

[0021] Transient stability constraints: Transient voltage stability requires recovery to above 0.8 pu within 10 seconds and above 0.9 pu over a long period; transient power angle stability of synchronous units across the entire network is required.

[0022] Dynamic stability constraints: Damping ratio for large disturbances reaches 0.01–0.015;

[0023] Thermal stability constraints: Key sections, lines, and main transformers all meet thermal stability or control limit requirements;

[0024] Constraints related to renewable energy: During transient processes, except for active tripping, renewable energy should not disconnect from the grid on a large scale due to voltage problems or insufficient system inertia support capacity. Furthermore, during fault recovery, renewable energy should not frequently enter and exit high / low voltage ride-through states, causing oscillations in the sending-end power grid system.

[0025] As a limitation, the actual operating factors of the power grid include the operating level of traditional generator units, the peak-shaving capacity of traditional generator units, the power supply load level, the power flow of key transmission sections, and the priority of new energy consumption.

[0026] The beneficial effects achieved by this invention, due to the adoption of the above-described solution, compared with the prior art, are as follows:

[0027] (1) The present invention provides a simulation evaluation method for the new energy carrying capacity of the power grid at the sending end. It takes into account the characteristics of the large power grid at the sending end, comprehensively considers the safety and stability constraints, power balance constraints and actual operation factors of the power grid, and comprehensively explores the new energy carrying capacity of the power system from multiple perspectives. It accurately identifies the key influencing factors that restrict the new energy carrying capacity, and provides a theoretical basis for the future planning and development of the power grid, the safe and stable operation of the system, and the large-scale internal consumption and external transmission of new energy.

[0028] (2) The present invention provides a simulation evaluation method for the carrying capacity of new energy in the sending-end power grid. For distributed new energy connected to the distribution network, after equalization with the same capacity, it is connected to the main grid according to the power source nature, instead of simply treating it as a negative load. This preserves the dynamic response characteristics of new energy and more realistically and accurately reflects the dynamic response of the power system during the evaluation of the carrying capacity of new energy, thereby more accurately evaluating the carrying capacity of new energy.

[0029] This invention is applicable to the simulation evaluation of the renewable energy carrying capacity of the sending-end power grid. Attached Figure Description

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0031] Figure 1 This is a diagram showing the factors affecting the renewable energy carrying capacity of the sending-end power grid in this embodiment;

[0032] Figure 2 This is a flowchart of a simulation evaluation method for the renewable energy carrying capacity of a power grid at the sending end, as described in this embodiment.

[0033] Figure 3 This embodiment shows the grid structure and distribution of new energy sources in part of the power grid.

[0034] Figure 4 Transient voltage curve for a fault in the DK-XT line in this embodiment;

[0035] Figure 5 This embodiment illustrates the impact of load levels and peak-shaving capacity on the carrying capacity of new energy sources.

[0036] Figure 6 This embodiment illustrates the impact of renewable energy consumption priority and cross-sectional power flow on renewable energy carrying capacity. Detailed Implementation

[0037] The present invention will be further described below with reference to the embodiments. However, those skilled in the art should understand that the present invention is not limited to the following embodiments. Any improvements and equivalent changes made based on the specific embodiments of the present invention are within the scope of protection of the claims of the present invention.

[0038] Example 1: A Simulation Evaluation Method for the Carrying Capacity of New Energy Sources in Sending-End Power Grids

[0039] Factors affecting the carrying capacity of new energy sources include safety and stability constraints, power balance constraints, and actual grid operation factors, such as... Figure 1 As shown.

[0040] Safety and stability constraints include frequency stability constraints, static voltage safety constraints, transient stability constraints, dynamic stability constraints, thermal stability constraints, and new energy-related constraints.

[0041] Frequency stability constraint: After a large disturbance (N-2 / N-3 fault) occurs in the sending-end power grid system and the tripping strategy of the safety and stability control system is considered, the lowest frequency of the sending-end power grid system should not cause the grid to perform low-frequency load shedding. The lowest frequency that will not cause the grid to perform low-frequency load shedding is 49.25Hz.

[0042] Static voltage safety constraint: refers to the initial power flow voltage of hub stations of 500kV and above meeting the lower limit of the operating voltage curve, and the voltage of 500kV stations can be adjusted back to 500kV after an N-1 fault;

[0043] Transient stability constraints: Transient voltage stability requires recovery to above 0.8 pu within 10 seconds and above 0.9 pu over a long period; transient power angle stability of synchronous units across the entire network is required.

[0044] Dynamic stability constraints: Damping ratio for large disturbances reaches 0.01–0.015;

[0045] Thermal stability constraints: Key sections, lines, and main transformers all meet thermal stability or stability control limit requirements;

[0046] Constraints related to renewable energy: During transient processes, except for active tripping, renewable energy should not disconnect from the grid on a large scale due to voltage problems or insufficient system inertia support capacity. Furthermore, during fault recovery, renewable energy should not frequently enter and exit high / low voltage ride-through states, causing oscillations in the sending-end power grid system.

[0047] Power balance constraints: For the sending-end power grid, power balance refers to the balance between the sum of the output of traditional units and the output of new energy sources and the sum of the power supply load (including plant power), the total network loss and the power transmitted to other regions. Power balance constraints refer to the constraints on the output of new energy sources caused by maintaining the above balance relationship under a certain operating mode of the power grid.

[0048] Actual operating factors of the power grid include the operating level of traditional generator units, the peak-shaving capacity of traditional generator units, the power supply load level, the power flow of key transmission sections, and the priority of renewable energy consumption.

[0049] This embodiment relies on a provincial power grid and uses PSD-BPA software to simulate and evaluate the renewable energy carrying capacity of the sending-end power grid. The partial grid structure and renewable energy distribution of the provincial power grid are shown below. Figure 3 As shown, the power grid in this embodiment uses a typical operating mode to explain steps S1-S4, and uses the new energy carrying capacity assessment results of eight typical operating modes to explain step S5.

[0050] A simulation evaluation method for the renewable energy carrying capacity of the sending-end power grid, the flowchart of which is as follows: Figure 2 As shown, the steps are performed sequentially:

[0051] S1. Distributed new energy sources connected to the distribution network in the sending-end power grid / system are equivalently processed using the same capacity new energy model and then connected to the main grid according to the power source nature. The actual operating factors of the power grid are adjusted according to the typical operating modes that occur in the actual operation of the power grid. In this embodiment, the total thermal power generation capacity is 36603MW, the thermal power unit output is 18599MW, the total wind power output is 18590MW, the power supply load is 27967MW (including self-provided load), the plant power load is 3319MW, and the total loss is 1066MW. The power flow situation of the main transmission sections is shown in Table 1.

[0052] Table 1. Cross-sectional tidal flow conditions

[0053] BWDH section / MW XBKD cross-section / MW HB section / MW HF section / MW WS section / MW 514 1015 2374 1629 4859

[0054] S2. Increase the output of new energy sources, while reducing the output of traditional generator sets according to their actual peak-shaving capacity, increasing the spinning reserve capacity of the sending-end grid / system, and making room for the transmission of new energy sources until the grid reaches at least one of the static safety constraint boundaries.

[0055] Static safety constraints include: increased output of new energy sources causing the voltage of hub stations to reach the lower limit of the operating voltage curve; power transmission from new energy gathering areas causing the main transformer to reach the thermal stability limit; key lines and sections of power transmission channels reaching the stability control limit; and power balance restrictions caused by insufficient peak-shaving capacity of traditional generator sets or key section control reaching the limit value.

[0056] In this embodiment, the power transmission from the new energy gathering area reaches the static safety constraint boundary, causing the main transformer to reach the thermal stability limit, and the key lines and sections of the power transmission channel to reach the stability control limit.

[0057] S3. Perform static analysis of N-1 fault, dynamic safety and stability verification of N-1 and N-2 faults. The dynamic safety and stability verification of N-2 fault needs to consider the machine switching strategy of the safety and stability control system and obtain the verification results.

[0058] Static analysis of N-1 fault: Static analysis of N-1 fault was performed on the 500kV line. The voltage after some faults is shown in Table 2.

[0059] Table 2 Static Analysis of Fault N-1 on 500kV Line

[0060]

[0061]

[0062] When the DK-XT line is faulty, the static voltage of the system drops below 500kV after the N-1 fault, and the power flow convergence result is inaccurate. Therefore, the stable value calculated by transient stability is used as the standard.

[0063] Based on transient stability analysis, the medium- and long-term bus voltages of typical wind power collection areas are as follows: HT station 0.971 pu (509.7 kV), BL station 0.954 pu (500.8 kV), WC station 0.978 pu (513.4 kV), CYZ station 0.984 pu (516.6 kV), HH station 0.987 pu (518.1 kV), BYGL station 0.976 pu (512.4 kV), HTL station 0.969 pu (508.7 kV), and DLS station 0.961 pu (504.5 kV). The transient voltage curves are shown below. Figure 4As shown, the voltage at each node recovers to above 0.8 pu in 10 seconds and above 0.9 pu over a longer period, which meets the requirements for transient voltage operation and satisfies the transient stability constraint. Since the bus voltage at BL station can recover to 500kV after the fault, it is at the boundary value of the static voltage safety constraint in the safety stability constraint. Therefore, it is determined that the new energy carrying capacity constraint factors under this typical operation mode also have static voltage safety constraints.

[0064] Dynamic safety and stability verification of N-1 and N-2 faults: Dynamic safety and stability verification of N-1 and N-2 faults of 500kV North-South Channel is carried out. Among them, the tripping strategy of N-2 needs to be considered. In this embodiment, the step-by-step tripping and linear tripping strategies are adopted. Only one type of N-1 and N-2 fault is listed here as an example, as shown in Tables 3 and 4.

[0065] Table 3. Stability Calculation Results for N-1

[0066]

[0067] Table 4. Stability calculation results for N-2

[0068]

[0069] Under the current typical operating mode, the power grid has a static voltage safety problem. The limiting fault is the N-1 fault of the DK-XT line. After the fault, the bus voltage of the BL station can be adjusted back to 0.954pu (500.8kV), which is within the static voltage safety constraint boundary. Moreover, the key sections, lines and main transformers of the new energy aggregation station all meet the thermal stability or control limit requirements, and satisfy the dynamic stability constraints, transient stability constraints, frequency stability constraints and new energy-related constraints.

[0070] S4. Based on the verification results, assess the limiting factors and scale of new energy carrying capacity under the current typical power grid operation mode;

[0071] If the verification result meets the safety and stability constraints, then the limiting factor of the new energy carrying capacity under the current typical operation mode is determined to be the static safety constraint boundary reached in step S2, and the total output of new energy at this time is taken as the new energy carrying capacity under the current typical operation mode of the power grid.

[0072] If the verification result does not meet the safety and stability constraints, reduce the output of new energy sources, and at the same time adjust the power flow of the sending-end grid / system within the static safety constraint boundary, then perform step S3 again until the verification result of step S3 meets the safety and stability constraints. Then, determine that the final safety and stability constraints reached are the limiting factors of the new energy carrying capacity, and take the total output of new energy sources at this time as the new energy carrying capacity under the current typical grid operation mode.

[0073] The verification result in this embodiment just meets the static voltage safety constraint in the safety and stability constraints, and is at the boundary value of the static voltage safety constraint in the safety and stability constraints. Therefore, in addition to the thermal stability constraints of the key sections, lines and main transformers in S2, the new energy carrying capacity constraints under this typical operation mode also include the static voltage safety constraint. Therefore, it is determined that the main constraints of the new energy carrying capacity under the current typical operation mode of the power grid in this embodiment are static voltage safety and thermal stability, and the new energy carrying capacity of the whole grid is 18590MW.

[0074] S5. Return to step S1, readjust the actual operating factors of the power grid to operate under another typical operating mode, and perform steps S2-S4 to compare and analyze the impact of the actual operating factors on the overall grid's renewable energy carrying capacity, and evaluate the influencing factors and carrying capacity scale of renewable energy carrying capacity under this operating mode; if the verification result meets the safety and stability constraints, then the renewable energy carrying capacity constraint factor under the current typical operating mode of the power grid is determined to be the factor in step S2. If the static safety constraint boundary is reached in step S2, and the total output of new energy at this point is taken as the new energy carrying capacity under the current typical operation mode of the power grid; if the verification result does not meet the safety and stability constraint, the output of new energy is reduced, and the power flow of the sending-end power grid / system is adjusted within the static safety constraint boundary, and then the operation of step S3 is performed again until the verification result of step S3 meets the safety and stability constraint. Then the safety and stability constraint finally reached is determined to be the limiting factor of new energy carrying capacity, and the total output of new energy at this point is taken as the new energy carrying capacity under the current typical operation mode of the power grid; if, during the adjustment of actual operating factors, due to power balance constraints, the typical operation mode does not reach the static safety constraint boundary in step S2, and the verification result of step S3 also meets the safety and stability constraint, then the power balance constraint is determined to be the limiting factor of new energy carrying capacity, and the total output of new energy at this point is taken as the new energy carrying capacity under the current typical operation mode of the power grid.

[0075] This embodiment lists the assessment results of renewable energy carrying capacity under eight different operating modes, and compares and illustrates the impact of several practical operating factors, including load level, peak-shaving capacity, cross-sectional power flow, and wind / solar power consumption priority. The results analysis diagram is shown below. Figure 5 , Figure 6 As shown.

[0076] Figure 5The results shown represent the renewable energy carrying capacity under the same thermal / hydropower generation levels and power flow of the transmission section, under the three operating modes. The simulation results show that the limiting factor for renewable energy carrying capacity under the three operating modes is static voltage safety. As the power supply load decreases, the reactive load and losses of the system decrease, the grid voltage level improves, and the renewable energy carrying capacity increases. At the same time, in order to ensure that the transmission section remains unchanged, the output of traditional generator units needs to be reduced synchronously, the system's spinning reserve capacity increases, the dynamic stability support capacity of the system is increased, and it is also conducive to the transmission of renewable energy.

[0077] Figure 6 The results shown for the five operating modes are an analysis of the impact of wind power and photovoltaic power consumption priorities and cross-sectional power flow on the carrying capacity of new energy sources under the same thermal / hydropower operating levels, peak-shaving capacity (50%), and power flow at the transmission section; comparison Figure 5 and Figure 6 Simulation results for 1 large load, 2 off-peak loads, and 5 small loads show that the grid's renewable energy carrying capacity is significantly improved after photovoltaic (PV) grid connection. This is because PV grid connection points are relatively dispersed, distributed in both the north and south of the grid, and individual power stations have small capacities and short transmission distances, resulting in better voltage support for the grid. In contrast, wind power is concentrated along the northern route, so the combination of wind and solar power generation has a significant impact on carrying capacity due to voltage safety concerns. Compared to wind power generation only along the northern route, prioritizing the combination of wind and solar power generation can improve the overall renewable energy carrying capacity of the entire grid.

[0078] contrast Figure 6 As can be seen from the three and four small loads, the carrying capacity of prioritizing photovoltaic power consumption and only consuming wind power is almost the same. Although the reduction of grid load level can improve the grid voltage support capacity and is conducive to improving the carrying capacity of new energy from a safety perspective, as the load decreases, the demand for power consumption of the whole grid decreases, and the constraint on the consumption capacity of new energy becomes the power balance constraint.

[0079] contrast Figure 6 As can be seen from the 4th and 5th loads, when the overall grid load is small and there is no demand for electricity, the peak-shaving capacity of traditional generator sets is constrained, and the renewable energy absorption capacity is determined by the power balance. If traditional generator sets have deep peak-shaving capacity (in this embodiment, the peak-shaving capacity of traditional generator sets reaches 35% under the current typical operation mode of the power grid), the renewable energy carrying capacity of the power grid can be fully tapped.

Claims

1. A simulation evaluation method for the renewable energy carrying capacity of a power grid at the sending end, characterized in that, Based on the factors influencing the carrying capacity of new energy sources, which include safety and stability constraints, power balance constraints, and actual grid operation factors, the simulation evaluation method for the carrying capacity of new energy sources in the sending-end power grid includes the following steps in sequence: S1. After the distributed new energy sources connected to the distribution network in the sending-end power grid are equivalently processed using the same capacity new energy model, they are connected to the main grid according to the power source nature. The actual operation factors of the power grid are adjusted according to the typical operation mode that occurs in the actual operation of the power grid. S2. Increase the output of new energy sources, and at the same time reduce the output of traditional generator sets according to the actual peak-shaving capacity of traditional generator sets, increase the spinning reserve capacity of the sending-end grid, and make room for the transmission of new energy sources until the grid reaches the static safety constraint boundary. S3. Perform static analysis of N-1 fault, dynamic safety and stability verification of N-1 and N-2 faults. The verification of N-2 fault needs to consider the machine switching strategy of the safety and stability control system, and obtain the verification results. S4. Based on the verification results, assess the limiting factors and scale of new energy carrying capacity under the current typical power grid operation mode; S5. Return to step S1, readjust the actual operating factors of the power grid to make the power grid operate under another typical operating mode, and proceed to steps S2-S4 to compare and analyze the impact of the actual operating factors on the new energy carrying capacity of the entire power grid, and evaluate the influencing factors and carrying capacity scale of the new energy carrying capacity under the current typical operating mode of the power grid.

2. The simulation and evaluation method for the renewable energy carrying capacity of a power grid at the sending end, as described in claim 1, is characterized in that... Static safety constraint boundaries include at least one of the following: increased output of new energy sources causing the voltage of the hub station to reach the lower limit of the operating voltage curve; power transmission from new energy gathering areas causing the main transformer to reach the thermal stability limit; key lines and sections of power transmission channels reaching the stability control limit; and power balance restrictions caused by insufficient peak-shaving capacity of traditional generator units or key section control reaching the limit value.

3. The simulation and evaluation method for the renewable energy carrying capacity of a power grid at the sending end, as described in claim 1, is characterized in that... In step S4, the limiting factors and scale of new energy carrying capacity are evaluated based on the verification results. Specifically, if the verification results meet the safety and stability constraints, the limiting factor of new energy carrying capacity under the current typical operating mode is determined to be the static safety constraint boundary reached in step S2, and the total output of new energy at this time is taken as the scale of new energy carrying capacity under the current typical operating mode of the power grid. If the verification results do not meet the safety and stability constraints, the output of new energy is reduced, and the power flow of the sending-end power grid is adjusted to be within the static safety constraint boundary. Then, the operation of step S3 is performed until the verification results of step S3 meet the safety and stability constraints. Then, the final safety and stability constraint reached is determined to be the limiting factor of new energy carrying capacity, and the total output of new energy at this time is taken as the scale of new energy carrying capacity under the current typical operating mode of the power grid.

4. The simulation evaluation method for the renewable energy carrying capacity of a power grid at the sending end according to claim 1, characterized in that, In step S5, the factors influencing the renewable energy carrying capacity and the carrying scale under the current typical operation mode of the power grid are evaluated. Specifically, if the verification result meets the safety and stability constraints, the renewable energy carrying capacity constraint under the current typical operation mode of the power grid is determined to be the static safety constraint boundary reached in step S2, and the total renewable energy output at this time is taken as the renewable energy carrying scale under the current typical operation mode of the power grid. If the verification result does not meet the safety and stability constraints, the renewable energy output is reduced, and the power flow of the sending-end power grid is adjusted to be within the static safety constraint boundary. Then, the operation of step S3 is performed until the verification result of step S3 meets the safety and stability constraints. Then, the final safety and stability constraint reached is determined to be the constraint factor of the renewable energy carrying capacity, and the total renewable energy output at this time is taken as the renewable energy carrying scale under the current typical operation mode of the power grid. If, during the adjustment of actual grid operating factors, the typical operating mode fails to reach the static safety constraint boundary in step S2 due to power balance limitations, and the verification result in step S3 also satisfies the safety and stability constraints, then the power balance constraint is determined to be a limiting factor for the new energy carrying capacity, and the total output of new energy at this time is taken as the new energy carrying capacity under the current typical grid operating mode.

5. The simulation evaluation method for the renewable energy carrying capacity of a power grid at the sending end according to claim 1, characterized in that, Safety and stability constraints include frequency stability constraints, static voltage safety constraints, transient stability constraints, dynamic stability constraints, thermal stability constraints, and new energy-related constraints. Frequency stability constraint: After a large disturbance (N-2 / N-3 fault) occurs in the sending-end power grid system and the tripping strategy of the safety and stability control system is considered, the lowest frequency of the sending-end power grid system should not cause the grid to perform low-frequency load shedding. The lowest frequency that will not cause the grid to perform low-frequency load shedding is 49.25Hz. Static voltage safety constraint: refers to the initial power flow voltage of hub stations of 500kV and above meeting the lower limit of the operating voltage curve, and the voltage of 500kV stations can be adjusted back to 500kV after an N-1 fault; Transient stability constraints: Transient voltage stability requires recovery to above 0.8 pu within 10 seconds and above 0.9 pu over a long period; transient power angle stability of synchronous units across the entire network is required. Dynamic stability constraints: The damping ratio for large disturbances reaches 0.01 to 0.015; Thermal stability constraints: Key sections, lines, and main transformers all meet thermal stability or control limit requirements; Constraints related to renewable energy: During transient processes, except for active tripping, renewable energy should not disconnect from the grid on a large scale due to voltage problems or insufficient system inertia support capacity. Furthermore, during fault recovery, renewable energy should not frequently enter and exit high / low voltage ride-through states, causing oscillations in the sending-end power grid system.

6. The simulation evaluation method for the renewable energy carrying capacity of a power grid at the sending end according to claim 1, characterized in that, Actual operating factors of the power grid include the operating level of traditional generator units, the peak-shaving capacity of traditional generator units, the power supply load level, the power flow of key transmission sections, and the priority of renewable energy consumption.

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