Calculation method and device for evaluating the overvoltage level suppression effect of new energy station access points considering transformer saturation characteristics

Abstract

The embodiment of the present invention provides a method and device for calculating an overvoltage level suppression effect evaluation index of a new energy station access point considering the saturation characteristics of a transformer, and relates to the field of power grid technology. The calculation method includes: using formula 1 to calculate the overvoltage suppression effect index K(n, i); wherein formula 1 is: #imgabs0# The calculation method and device can evaluate the impact of the saturation characteristics of the transformer on the overvoltage of new energy equipment, and provide an optimized strategy for the safe and stable operation and security control measures of new energy equipment.

Description

Technical Field

[0001] The present invention relates to the field of power grid technology, and in particular to a method and device for calculating an evaluation index of an overvoltage level suppression effect at a new energy station access point taking into account transformer saturation characteristics. Background Art

[0002] With the massive construction of new energy access projects such as DC, wind power, and photovoltaics, the proportion of power electronic equipment in the power grid has increased dramatically, and the power supply and power grid structure has continued to undergo major changes. Factors such as power obstruction and shock caused by various forms of cross-regional DC faults have led to increasing safety risks in the power grid. New energy such as wind power will continue to grow, and the characteristics of a high proportion of new energy power grids will become more and more obvious. At the same time, the installed capacity of traditional rotating synchronous generators has gradually decreased, and the proportion of new energy characterized by low inertia and weak support in the power grid has continued to increase, which has also brought safety risks to the stable operation of the power grid.

[0003] The traditional electromechanical transient simulation program can no longer meet the simulation accuracy requirements when facing complex scenarios such as commutation failure and subsynchronous oscillation. Therefore, electromagnetic transient simulation is currently required for the dynamic characteristics analysis of actual power grids.

[0004] When faults such as grounding short circuit of AC transmission line and commutation failure of DC transmission converter occur in the power system, the voltage level of the entire power grid will fluctuate greatly, especially the overvoltage at the access points of new energy sources such as wind turbines. In fact, in electromagnetic transient simulation, the saturation characteristics of the transformer on the topological link of the power grid where the new energy equipment is located will greatly affect the overvoltage level of the new energy equipment, and further affect the accuracy of the electromagnetic transient simulation results.

[0005] However, the current electromagnetic transient simulation of the power grid does not consider the saturation characteristics of all transformers for two reasons. First, the saturation characteristics of the transformer will affect the efficiency of the electromagnetic transient simulation. In addition, turning on a large number of transformer saturation characteristics will lead to reduced numerical stability, and the electromagnetic transient simulation may not converge. In this regard, one solution is to evaluate the impact of the saturation characteristics of each transformer on the overvoltage of renewable energy, select the transformers with greater saturation characteristics to turn on the saturation characteristics, and disable saturation for the remaining transformers. There is still a lack of research on evaluating the impact of transformer saturation characteristics, so this application proposes an indicator for evaluating the impact of transformer saturation characteristics on overvoltage levels. Summary of the invention

[0006] The purpose of the present invention includes providing a calculation method and device for evaluating the overvoltage level suppression effect of a new energy station access point taking into account the saturation characteristics of the transformer, which can evaluate the impact of the saturation characteristics of the transformer on the overvoltage of new energy equipment and provide an optimized strategy for the safe and stable operation and security control measures of new energy equipment.

[0007] The embodiments of the present invention can be implemented as follows:

[0008] In a first aspect, the present invention provides a method for calculating an evaluation index of an overvoltage level suppression effect of a new energy station access point considering transformer saturation characteristics, the calculation method comprising:

[0009] The overvoltage suppression effect index K(n, i) is calculated using formula 1;

[0010] Among them, formula 1 is:

[0011]

[0012] Where V 0i V is the maximum overvoltage per unit value of the access point of new energy equipment i when all N transformers on the link are disabled for saturation; V 1i is the maximum overvoltage per unit value at the access point of new energy equipment i when all N transformers on the link are turned on and saturated; Q S1n When all N transformers on the link are turned on and saturated, the nth transformer is c The total reactive power absorbed during the time; Q S1m When all N transformers on the link are turned on and saturated, the mth transformer is at t c The total reactive power absorbed during the time; Q S0n When all N transformers on the link are disabled for saturation, the nth transformer is c The total reactive power absorbed during the time; Q S0m When all N transformers on the link are disabled for saturation, the mth transformer is c The total reactive power absorbed during the time t c The time it takes for the system to recover to stability after a failure; 1≤n≤N, 1≤m≤N.

[0013] In an optional implementation, before the step of calculating the overvoltage suppression effect index K(n, i) using formula 1, the calculation method further includes:

[0014] Use formula 2 to calculate Q S1n , Q S1m , Q S0n and Q S0m ;

[0015] Among them, formula 2 is:

[0016]

[0017] In the formula, j represents 0 or 1; x represents m or n; t s is the failure time; Q 0m(t) is the change of reactive power absorbed by the mth transformer over time when all N transformers on the link are disabled from saturation; Q 0n (t) is the variation of reactive power absorbed by the nth transformer over time when all N transformers on the link are disabled from saturation; Q 1m (t) is the change of reactive power absorbed by the mth transformer over time when all N transformers on the link are turned on and saturated; Q 1n (t) is the variation of reactive power absorbed by the nth transformer over time when all N transformers on the link are turned on and saturated.

[0018] In an optional embodiment, when Q is calculated using Formula 2 S1n , Q S1m , Q S0n and Q S0m Before the step of, the calculation method further comprises:

[0019] For the actual power grid system, set up a fault scenario;

[0020] Perform electromagnetic transient simulation and record V 0i 、V 1i , Q 0m (t), Q 0n (t), Q 1m (t), Q 1n (t), t s and t c .

[0021] In an optional embodiment, electromagnetic transient simulation is performed to record V 0i 、V 1i , Q 0m (t), Q 0n (t), Q 1m (t) and Q 1n The steps of (t) include:

[0022] Set all transformers on the link where new energy equipment i is located to disable saturation characteristics and run electromagnetic transient simulation;

[0023] Record V 0i , Q 0m (t), Q 0n (t)t s and t c .

[0024] In an optional embodiment, electromagnetic transient simulation is performed to record V 0i 、V 1i , Q 0m (t), Q 0n (t), Q 1m (t) and Q1n The step (t) further comprises:

[0025] Set all transformers on the link where new energy equipment i is located to enable saturation characteristics and run electromagnetic transient simulation;

[0026] Record V 1i , Q 1m (t) and Q 1n (t).

[0027] In an optional implementation, after the step of calculating the overvoltage suppression effect index K(n, i) using formula 1, the calculation method further includes:

[0028] Determine whether all new energy devices have been traversed;

[0029] If not, K(n, i) is calculated for the new energy equipment that has not been traversed yet, until K(n, i) of all new energy equipment is calculated.

[0030] In a second aspect, the present invention provides a device for calculating an evaluation index of an overvoltage level suppression effect of a new energy station access point considering transformer saturation characteristics, the computing device comprising:

[0031] The memory stores a formula 1 for calculating an overvoltage suppression effect index K(n, i), where the formula 1 is:

[0032]

[0033] Where V 0i V is the maximum overvoltage per unit value of the access point of new energy equipment i when all N transformers on the link are disabled for saturation; V 1i is the maximum overvoltage per unit value at the access point of new energy equipment i when all N transformers on the link are turned on and saturated; Q S1n When all N transformers on the link are turned on and saturated, the nth transformer is c The total reactive power absorbed during the time; Q S1m When all N transformers on the link are turned on and saturated, the mth transformer is at t c The total reactive power absorbed during the time; Q S0n When all N transformers on the link are disabled for saturation, the nth transformer is c The total reactive power absorbed during the time; Q S0m When all N transformers on the link are disabled for saturation, the mth transformer is c The total reactive power absorbed during the time t c The time from failure to system restoration of stability; 1≤n≤N, 1≤m≤N;

[0034] The processor is used to read Formula 1 in the memory to calculate the overvoltage suppression effect index K(n, i).

[0035] In an optional embodiment, the memory further stores a method for calculating Q S1n , Q S1m , Q S0n and Q S0m Formula 2, Formula 2 is:

[0036]

[0037] In the formula, j represents 0 or 1; x represents m or n; t s is the failure time; Q 0m (t) is the change of reactive power absorbed by the mth transformer over time when all N transformers on the link are disabled from saturation; Q 0n (t) is the variation of reactive power absorbed by the nth transformer over time when all N transformers on the link are disabled from saturation; Q 1m (t) is the change of reactive power absorbed by the mth transformer over time when all N transformers on the link are turned on and saturated; Q 1n (t) is the change of reactive power absorbed by the nth transformer over time when all N transformers on the link are turned on and saturated;

[0038] The processor is used to read Formula 2 in the memory to calculate Q S1n , Q S1m , Q S0n and Q S0m .

[0039] In an optional implementation, the processor is further configured to set a fault scenario for the actual power grid system; perform electromagnetic transient simulation, and record V 0i 、V 1i , Q 0m (t), Q 0n (t), Q 1m (t), Q 1n (t), t s and t c .

[0040] In an optional implementation manner, the processor is further configured to disable saturation characteristics of all transformers on the link where the new energy device i is located, and to run electromagnetic transient simulation; record V 0i , Q 0m (t), Q 0n (t), t s and t c ; Set all transformers on the link where new energy equipment i is located to enable saturation characteristics and run electromagnetic transient simulation; record V 1i , Q1m (t) and Q 1n (t).

[0041] The beneficial effects of the method and device for calculating the overvoltage level suppression effect evaluation index of the new energy station access point considering the transformer saturation characteristics provided by the embodiment of the present invention include:

[0042] 1. The electromagnetic transient simulation calculation results are used as the data source for the proposed index calculation, which has high accuracy;

[0043] 2. By comparing the reactive power absorption and overvoltage values ​​of transformers without saturation and with saturation, the suppression effect of transformer saturation characteristics on overvoltage can be accurately described;

[0044] 3. In the calculation method of the index, the coupling relationship between the effects of saturation of multiple transformers on overvoltage suppression under a single chain is taken into account, and the overvoltage suppression effect of a single transformer is calculated by using reactive power as a weight, which is accurate and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0046] Figure 1 A flow chart of a method for calculating an evaluation index of an overvoltage level suppression effect of a new energy station access point considering transformer saturation characteristics provided by an embodiment of the present invention;

[0047] Figure 2 Overvoltage curve of the fan access point when there is no saturation and single chain saturation;

[0048] Figure 3 This is the curve of reactive power absorbed by the first transformer changing with time;

[0049] Figure 4 This is the curve of the reactive power absorbed by the second transformer changing with time. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, 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 part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0051] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0053] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0054] When the power system is grounded due to a short circuit in a transmission line somewhere, the voltage level of the power grid will fluctuate for a certain period of time, and a large transient overvoltage will appear at the access point of new energy equipment such as wind turbines. In order to ensure the safe operation of new energy equipment, safety control measures such as machine cutting must be taken when overvoltage occurs. However, in reality, the saturation characteristics of many transformers in the power grid will have a great impact on the transient overvoltage at the access point of new energy equipment. In order to accurately evaluate the safety control operation threshold overvoltage of new energy equipment, it is necessary to first evaluate the suppression effect of the transformer saturation characteristics in the power grid on the overvoltage level of the new energy access point.

[0055] This embodiment proposes an evaluation index and calculation method for suppressing overvoltage levels at renewable energy access points taking into account transformer saturation characteristics. For power grid fault scenarios, electromagnetic transient simulation is used to calculate renewable energy overvoltages and transformer absorbed reactive power when transformer saturation characteristics are turned on or off, and an evaluation index for suppressing overvoltage levels is calculated.

[0056] Please refer to Figure 1 This embodiment provides a calculation method for evaluating the overvoltage level suppression effect of a new energy station access point considering the transformer saturation characteristics (hereinafter referred to as the calculation method). The calculation method is used to measure the operation scenario of the overvoltage level suppression effect evaluation index, and the main calculation process of the proposed index based on electromagnetic transient simulation is designed. The proposed calculation method of the evaluation index can be used to guide the construction of power grids and prevent accidents, for example, it can guide the setting of the overvoltage cut-off threshold of new energy power generation equipment.

[0057] The calculation method includes the following steps:

[0058] S1: Set a fault scenario for the actual power grid system.

[0059] Specifically, for the electromagnetic transient simulation example of the actual power grid system, a typical fault scenario of N-2 fault, N-1 fault or DC commutation failure is set, where N represents the total number of transformers on the link.

[0060] S2: Set all transformers on the link where new energy equipment i is located to disable saturation characteristics, run electromagnetic transient simulation, and record V 0i , Q 0m (t), Q 0n (t), t s and t c .

[0061] Specifically, all transformers on the link where the new energy device i is located are set to disable saturation characteristics, and run electromagnetic transient simulation; record the maximum overvoltage per unit value V at the access point of the new energy device i 0i Assume that there are N transformers in the transformer chain where the new energy equipment i is located, and the reactive power absorbed by the nth transformer changes with time as Q 0n (t), the reactive power absorbed by the mth transformer changes with time as Q 0m (t), the failure time is t s , the time from failure to system restoration is t c ; 1≤n≤N, 1≤m≤N.

[0062] S3: Set all transformers on the link where new energy equipment i is located to enable saturation characteristics, run electromagnetic transient simulation, and record V 1i , Q 1m (t) and Q 1n (t).

[0063] Specifically, the saturation characteristics of the N transformers on the link where the new energy device i is located are enabled, and the electromagnetic transient simulation is re-run to calculate the maximum overvoltage per unit value at the access point of the new energy device i as V 1i , the reactive power absorbed by the mth transformer changes with time as Q 1m (t), the reactive power absorbed by the nth transformer changes with time as Q 1n (t).

[0064] S4: Calculate the overvoltage suppression effect index K(n, i) using formula 1.

[0065] The physical meaning of the proposed overvoltage suppression effect index K(n, i) is the overvoltage suppression effect of the saturation characteristic of transformer n on the access point i of new energy equipment.

[0066] Among them, formula 1 is:

[0067]

[0068] Where V 0i V is the maximum overvoltage per unit value of the access point of new energy equipment i when all N transformers on the link are disabled for saturation; V 1i is the maximum overvoltage per unit value at the access point of new energy equipment i when all N transformers on the link are turned on and saturated; Q S1n When all N transformers on the link are turned on and saturated, the nth transformer is c The total reactive power absorbed during the time; Q S1m When all N transformers on the link are turned on and saturated, the mth transformer is at t c The total reactive power absorbed during the time; Q S0n When all N transformers on the link are disabled for saturation, the nth transformer is c The total reactive power absorbed during the time; Q S0m When all N transformers on the link are disabled for saturation, the mth transformer is c The total reactive power absorbed during the time.

[0069] Q S1n , Q S1m , Q S0n and Q S0m The formula 2 is used to calculate:

[0070]

[0071] In the formula, j represents 0 or 1; x represents m or n.

[0072] S5: Determine whether all new energy devices have been traversed.

[0073] If not, for the new energy devices that have not been traversed, the process returns to S2 and continues until S6: K(n, i) of all new energy devices is calculated.

[0074] This embodiment also provides a calculation device (hereinafter referred to as: calculation device) for evaluating the overvoltage level suppression effect of a new energy station access point taking into account the saturation characteristics of the transformer. The calculation device includes a memory and a processor. The processor is used to read the program in the memory to implement the calculation method of the aforementioned implementation method.

[0075] Example

[0076] For an actual power grid system, a DC commutation failure is set, and the overvoltage curve of the wind turbine access point when there is no saturation and single-chain saturation can be observed, such as Figure 2 As shown in the figure, DC commutation failure occurs at 2.5 seconds.

[0077] The maximum overvoltage change at the fan access point is:

[0078] V11 -V 01 =1.328-1.287=0.041

[0079] There are two transformers in the link where the wind turbine is located, namely a 110kV transformer and a 37kV transformer, which are respectively denoted as the first transformer and the second transformer. The reactive power absorbed by the first transformer changes with time as shown in the figure below: Figure 3 As shown in the figure, the reactive power absorbed by the second transformer changes with time as shown in the figure Figure 4 shown.

[0080] For the first transformer, the calculation is:

[0081] Q S11 -Q S01 =2.3501e+02MVA

[0082] For the second transformer, the calculation is:

[0083] Q S12 -Q S02 =2.3666e+03MVA

[0084] Based on this, the evaluation index values ​​K(1,1) and K(2,1) of the saturation characteristics of the two transformers for the overvoltage suppression effect of the wind turbine connection can be calculated respectively:

[0085] K(1,1)=(V 11 -V 01 )*(Q S11 -Q S01 ) / (Q S11 -Q S01 +Q S12 -Q S02 )=0.370%

[0086] K(2,1)=(V 11 -V 01 )*(Q S12 -Q S02 ) / (Q S11 -Q S01 +Q S12 -Q S02 )=3.729%

[0087] By calculating the suppression effect evaluation index of the overvoltage level at the new energy access point considering the saturation characteristics of the transformer based on electromagnetic transient simulation, the impact of the saturation characteristics of the transformer on the overvoltage of the new energy equipment can be evaluated, and the optimized strategy scheme can be provided for the safe and stable operation and security control measures of the new energy equipment.

[0088] The beneficial effects of the calculation method and device provided in this embodiment include:

[0089] 1. The electromagnetic transient simulation calculation results are used as the data source for the proposed index calculation, which has high accuracy;

[0090] 2. By comparing the reactive power absorption and overvoltage values ​​of transformers without saturation and with saturation, the suppression effect of transformer saturation characteristics on overvoltage can be accurately described;

[0091] 3. In the calculation method of the index, the coupling relationship between the effects of saturation of multiple transformers on overvoltage suppression under a single chain is taken into account, and the overvoltage suppression effect of a single transformer is calculated by using reactive power as a weight, which is accurate and reliable.

[0092] 4. The results generated by this embodiment can be used to screen transformers with greater saturation characteristics. In further electromagnetic transient simulation analysis, only transformers with greater saturation characteristics can be turned on, taking into account simulation efficiency, accuracy and numerical stability.

[0093] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for calculating the overvoltage level suppression effect evaluation index of a new energy station access point considering the transformer saturation characteristics, characterized in that: The calculation method includes: The overvoltage suppression effect index K (n, i) is calculated using formula 1; Wherein, the formula 1 is: Where V 0i V is the maximum overvoltage per unit value of the access point of new energy equipment i when all N transformers on the link are disabled for saturation; V 1i is the maximum overvoltage per unit value at the access point of new energy equipment i when all N transformers on the link are turned on and saturated; Q S1n When all N transformers on the link are turned on and saturated, the nth transformer is t c The total reactive power absorbed during the time; Q S1m When all N transformers on the link are turned on and saturated, the mth transformer is t c The total reactive power absorbed during the time; Q S0n When all N transformers on the link are disabled for saturation, the nth transformer is t c The total reactive power absorbed during the time; Q S0m When all N transformers on the link are disabled for saturation, the mth transformer is t c Total reactive power absorbed during time; t c The time from failure to system restoration to stability; 1≤n≤N, 1≤m≤N; Before the step of calculating the overvoltage suppression effect index K(n, i) by using formula 1, the calculation method further includes: Use formula 2 to calculate Q S1n , Q S1m , Q S0n and Q S0m ; Wherein, the formula 2 is: In the formula, j represents 0 or 1; x represents m or n; t s is the failure time; Q 0m (t) is the change of reactive power absorbed by the mth transformer over time when all N transformers on the link are disabled for saturation; Q 0n (t) is the variation of reactive power absorbed by the nth transformer over time when all N transformers on the link are disabled for saturation; Q 1m (t) is the change of reactive power absorbed by the mth transformer over time when all N transformers on the link are turned on and saturated; Q 1n (t) is the variation of reactive power absorbed by the nth transformer over time when all N transformers on the link are turned on and saturated; In the formula 2, Q is calculated S1n , Q S1m , Q S0n and Q S0m Before the step of, the calculation method further comprises: For the actual power grid system, set up a fault scenario; Perform electromagnetic transient simulation and record V 0i 、V 1i , Q 0m (t)Q 0n (t)Q 1m (t)Q 1n (t), t s and t c .

2. The calculation method of the overvoltage level suppression effect evaluation index of the new energy station access point considering the transformer saturation characteristics according to claim 1 is characterized in that: The electromagnetic transient simulation is performed and V 0i 、V 1i , Q 0m (t)Q 0n (t)Q 1m (t) and Q 1n The steps of (t) include: Set all transformers on the link where new energy equipment i is located to disable saturation characteristics and run electromagnetic transient simulation; Record V 0i , Q 0m (t)Q 0n (t), t s and t c .

3. The calculation method of the evaluation index of the overvoltage level suppression effect of the new energy station access point considering the transformer saturation characteristics according to claim 1 is characterized in that: The electromagnetic transient simulation is performed and V 0i 、V 1i , Q 0m (t)Q 0n (t)Q 1m (t) and Q 1n The step (t) further comprises: Set all transformers on the link where new energy equipment i is located to enable saturation characteristics and run electromagnetic transient simulation; Record V 1i , Q 1m (t) and Q 1n (t).

4. The calculation method of the overvoltage level suppression effect evaluation index of the new energy station access point considering the transformer saturation characteristics according to claim 1 is characterized in that: After the step of calculating the overvoltage suppression effect index K(n, i) by using formula 1, the calculation method further includes: Determine whether all new energy devices have been traversed; If not, K(n, i) is calculated for the new energy equipment that has not been traversed yet, until K(n, i) of all the new energy equipment is calculated.

5. A device for calculating the overvoltage level suppression effect evaluation index of a new energy station access point considering the transformer saturation characteristics, characterized in that: The computing device comprises: The memory stores a formula 1 for calculating an overvoltage suppression effect index K(n, i), wherein the formula 1 is: Where V 0i V is the maximum overvoltage per unit value of the access point of new energy equipment i when all N transformers on the link are disabled for saturation; V 1i is the maximum overvoltage per unit value at the access point of new energy equipment i when all N transformers on the link are turned on and saturated; Q S1n When all N transformers on the link are turned on and saturated, the nth transformer is t c The total reactive power absorbed during the time; Q S1m When all N transformers on the link are turned on and saturated, the mth transformer is t c The total reactive power absorbed during the time; Q S0n When all N transformers on the link are disabled for saturation, the nth transformer is t c The total reactive power absorbed during the time; Q S0m When all N transformers on the link are disabled for saturation, the mth transformer is t c Total reactive power absorbed during time; t c The time from failure to system restoration to stability; 1≤n≤N, 1≤m≤N; A processor, configured to read the formula 1 in the memory to calculate the overvoltage suppression effect index K(n, i); The memory also stores the information for calculating Q S1n , Q S1m , Q S0n and Q S0m Formula 2, the formula 2 is: In the formula, j represents 0 or 1; x represents m or n; t s is the failure time; Q 0m (t) is the change of reactive power absorbed by the mth transformer over time when all N transformers on the link are disabled for saturation; Q 0n (t) is the variation of reactive power absorbed by the nth transformer over time when all N transformers on the link are disabled for saturation; Q 1m (t) is the change of reactive power absorbed by the mth transformer over time when all N transformers on the link are turned on and saturated; Q 1n (t) is the variation of reactive power absorbed by the nth transformer over time when all N transformers on the link are turned on and saturated; The processor is used to read the formula 2 in the memory to calculate Q S1n , Q S1m , Q S0n and Q S0m ; The processor is also used to set a fault scenario for the actual power grid system; perform electromagnetic transient simulation, and record V 0i 、V 1i , Q 0m (t)Q 0n (t)Q 1m (t)Q 1n (t), t s and t c .

6. The device for calculating the overvoltage level suppression effect evaluation index of the new energy station access point considering the transformer saturation characteristics according to claim 5 is characterized in that: The processor is also used to set all transformers on the link where the new energy device i is located to disable saturation characteristics and run electromagnetic transient simulation; record V 0i , Q 0m (t)Q 0n (t), t s and t c ; Set all transformers on the link where new energy equipment i is located to enable saturation characteristics and run electromagnetic transient simulation; record V 1i , Q 1m (t) and Q 1n (t).

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