A method and system for calculating generator tripping sensitivity for transient stability control

Abstract

The application provides a method and system for calculating generator tripping sensitivity for transient stability control, which comprises the following steps: grouping generators by using power system instability scene power angle trajectory data and combining complex power angle algorithm; calculating the comprehensive difference of accumulated unbalanced energy and decelerable area of equivalent generators before and after generator tripping to form an estimated value of unbalanced energy directly taken away by generator tripping; calculating the electromagnetic power transfer amount of tripped generators by using power flow information and power system network topology at the time of generator tripping, combining the change of decelerable area caused by the translation of equivalent generator power angle curve; finally, calculating the change of stability margin by adding the unbalanced energy directly taken away by generator tripping and the change of decelerable area corresponding to power transfer, and dividing the capacity of tripped generators to calculate the generator tripping sensitivity. Based on the method, a system for calculating generator tripping sensitivity for transient stability control is provided. The application provides application prospect for online or real-time transient stability control generator tripping scheme optimization decision.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new power system emergency control technology, in particular to a method and system for calculating generator tripping sensitivity for transient stability control. BACKGROUND

[0002] When a power system suffers from a serious disturbance, it may cause the generator to lose step and the power angle to become unstable, i.e., the transient stability cannot be guaranteed. Generator tripping has the characteristics of rapid implementation, significant effect of avoiding power angle instability, and small impact on user power supply, and thus is the most important control means for maintaining the transient stability of the power system when a serious fault occurs. However, generator tripping inevitably causes active power loss and changes in the power grid structure, and excessive generator tripping may lead to subsequent problems such as insufficient system thermal reserve and frequency drop. How to reduce the total capacity of generator tripping as much as possible while guaranteeing the control target of system stability is the main problem that needs to be considered in generator tripping control.

[0003] The key to generator tripping scheme optimization is to quickly identify the most unstable generator and the most sensitive generator, and to remove the generator that has the greatest impact on system stability, thereby minimizing the total capacity of generator tripping. Currently, there are two main methods for generator tripping scheme optimization. One method is to first calculate the total capacity of generator tripping based on the energy function method or the EEAC theory, and then combine engineering experience, such as using the electrical distance between the generator and the fault location, the power angle deviation, or the acceleration trend to represent the sensitivity of generator tripping, and then selecting the tripping location according to the above indicators until the total capacity of generator tripping meets the requirements. The other method is to first construct an optimization decision model for generator tripping control, and then linearize the model by quantifying the impact of removing different generators on the stability margin of the power system using the sensitivity of generator tripping, and directly determine the optimal tripping location and capacity by solving the linear optimization decision model. The first method adopts the idea of calculating the total capacity first and then decomposing, and can calculate the total capacity of generator tripping without simulation, which is fast and can be used for online or real-time transient stability control optimization decision, but the method simplifies the calculation of the total capacity of generator tripping by only considering the change in mechanical power of the equivalent system, which cannot take into account the changes in equivalent electromagnetic power of the critical generator group, system inertia time constant, and other parameters after generator tripping, resulting in inaccurate total capacity of generator tripping. Moreover, the method of determining the tripping location based on the generator output, electrical distance, or power angle lead time lacks theoretical support, and it is usually difficult to obtain the optimal generator tripping scheme. The second method simultaneously determines the tripping amount and location, which is theoretically more complete, but it is difficult to obtain the sensitivity of generator tripping, which is the key to applying this method.

[0004] To obtain the cutting machine sensitivity, one way is to obtain the state trajectory of each electrical quantity of the system through super real-time simulation, and then calculate the stability margin change quantity combined with the stability margin quantitative theory, and calculate the sensitivity by numerical difference method. However, the method of calculating the sensitivity based on super real-time simulation has high requirements on simulation calculation performance and it is difficult to balance the detailed level of the model and the rapidity of the sensitivity calculation: when applied to online stability control, it needs to generate an optimized cutting machine scheme for a large number of faults that may occur in several typical scenarios within a few minutes (typically 15 minutes), so the hardware configuration requirement is high and the model refinement degree is limited; when applied to real-time stability control, it also faces challenges in computing resources and accuracy to generate an optimized cutting machine scheme for a single fault in a single operating scenario within a few hundred milliseconds (typically 100 milliseconds). Another way is to generate a large number of cutting machine sensitivity samples under typical scenarios and faults, and through offline training, the data rules are fixed into a neural network, and the cutting machine sensitivity of the specified scenario and fault is obtained within 1ms through online mapping during online or real-time stability control. However, the sensitivity acquisition method based on neural network has the problem of generalization difficulty, which may increase the error of sensitivity calculation due to changes in operating mode or instability mode, thereby affecting the cutting machine control effect. Therefore, how to quickly and accurately calculate the cutting machine sensitivity at different positions and then support the subsequent cutting machine scheme optimization has become an important technical point of transient stability control. SUMMARY

[0005] The purpose of the embodiments of the present application is to provide a cutting machine sensitivity calculation method and system for transient stability control, which can accurately and quickly calculate the stability margin change quantity of different cutting machine schemes based on real-time state information of the power grid, and further divide the stability margin change quantity by the cutting amount of the cutting machine unit to calculate the cutting machine sensitivity.

[0006] In a first aspect, the present application provides a cutting machine sensitivity calculation method for transient stability control, comprising the following steps:

[0007] Obtain the instability scenario trajectory data according to the stability control mode of the instability scenario; calculate the composite power angle difference value using the instability scenario trajectory data, and divide the units into leading groups and lagging groups based on the composite power angle difference value;

[0008] Using the system trajectory data from the fault to the cutting machine time as input, the electromagnetic power angle curve and the mechanical power angle curve are determined by using the extended equal-area criterion; the acceleration area, the deceleration area and the remaining deceleration area of the equivalent unit before and after cutting are calculated according to the grouping result using the electromagnetic power angle curve and the mechanical power angle curve; and then the imbalance energy jump caused by cutting is calculated;

[0009] Using the cutting machine time flow information and the power system network topology as input, the electromagnetic power transfer amount of the cutting machine unit is calculated, and the deceleration area change quantity is calculated assuming that the cutting causes the equivalent unit power angle curve to shift;

[0010] The unstable energy sudden change quantity of the cut machine is corresponding to the change quantity of the deceleration area of the power transfer, and the change quantity of the stable margin is calculated, and the cut machine sensitivity is calculated by dividing the cut machine quantity of the cut machine group.

[0011] In a second aspect, the application provides a cut machine sensitivity calculation system for transient stability control, comprising a grouping module, a first calculation module, a second calculation module and a third calculation module.

[0012] The grouping module is used to obtain unstable scene trajectory data according to the stability control mode of the unstable scene; the composite power angle difference value is calculated by using the unstable scene trajectory data, and the units are divided into leading groups and lagging groups based on the composite power angle difference value.

[0013] The first calculation module is used to take the system trajectory data from the fault to the cut machine time as input, and determine the electromagnetic power angle curve and the mechanical power angle curve by using the extended equal-area criterion; the acceleration area, the deceleration area and the remaining deceleration area of the equivalent unit before and after the cut machine are calculated according to the grouping result by using the electromagnetic power angle curve and the mechanical power angle curve; then the unstable energy sudden change quantity caused by the cut machine is calculated.

[0014] The second calculation module is used to take the power flow information at the cut machine time and the power system network topology as input, calculate the electromagnetic power transfer quantity of the cut machine group, and calculate the change quantity of the deceleration area corresponding to the power transfer assuming that the cut machine causes the equivalent unit power angle curve to shift.

[0015] The third calculation module is used to calculate the stable margin change quantity by the unstable energy sudden change quantity of the cut machine corresponding to the change quantity of the deceleration area of the power transfer, and calculate the cut machine sensitivity by dividing the cut machine quantity of the cut machine group.

[0016] The effects provided in the summary of the invention are only the effects of the embodiments, not all the effects of the invention, and one of the above technical solutions has the following advantages or beneficial effects:

[0017] The application provides a method and system for calculating the sensitivity of generator tripping for transient stability control, which comprises the following steps: obtaining trajectory data of an unstable scenario according to the stability control mode of the unstable scenario; calculating the composite power angle difference value by using the trajectory data of the unstable scenario, and dividing the units into leading and lagging groups based on the composite power angle difference value; taking the system trajectory data from the fault to the tripping time as input, and determining the electromagnetic power angle curve and the mechanical power angle curve by using the extended equal-area criterion; calculating the accelerated area, the decelerated area and the remaining decelerated area of the equivalent units before and after the tripping by using the electromagnetic power angle curve and the mechanical power angle curve according to the grouping result; then calculating the imbalance energy mutation caused by the tripping; taking the power flow information and the network topology of the power system at the tripping time as input, calculating the electromagnetic power transfer of the tripped units, and assuming that the power angle curve of the equivalent units is translated and changed to calculate the change of the decelerated area; calculating the stability margin change by using the imbalance energy mutation caused by the tripping and the change of the decelerated area corresponding to the power transfer, and dividing the tripping amount of the tripped units to calculate the tripping sensitivity. Based on the method for calculating the sensitivity of generator tripping for transient stability control, a system for calculating the sensitivity of generator tripping for transient stability control is also provided. The application uses the power angle, the speed, the electromagnetic and mechanical power, the terminal voltage and the active and reactive power output information of the power system at the tripping time and before the tripping time under the basic unstable scenario, and calculates the tripping sensitivity of each trippable unit by using algebraic operation, so that the time-consuming for calculation is small, the calculation method is simple, the time sequence trajectory of each electrical quantity of the power system after the tripping is not needed, and the application can provide basic information for the sensitivity-based control sensitive point screening and the optimal tripping scheme generation, and has a certain application prospect in the online or real-time transient stability control tripping scheme optimization decision. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and serve to explain the principles of the application, and do not limit the application in any way. In the drawings:

[0019] Figure 1 A flowchart of a method for quickly calculating the sensitivity of generator tripping for transient stability control is provided for the embodiment 1 of the application;

[0020] Figure 2 A flowchart of the grouping of generator units based on the composite power angle algorithm is provided for the embodiment 1 of the application;

[0021] Figure 3 A relationship diagram of each time node is provided for the embodiment 1 of the application;

[0022] Figure 4 A flowchart of the calculation of the imbalance energy mutation caused by the tripping of the generator based on the EEAC is provided for the embodiment 1 of the application;

[0023] Figure 5 Equivalent power angle curve of different stability control modes proposed for embodiment 1 of the present application;

[0024] Figure 6 Equivalent power angle characteristic curve before and after rejecting the cut-off unit proposed for embodiment 1 of the present application;

[0025] Figure 7 Flowchart for calculating change amount of decelerable area considering continuous impact of power transfer proposed for embodiment 1 of the present application;

[0026] Figure 8 Flowchart for calculating unit cutting sensitivity based on stability margin change amount proposed for embodiment 1 of the present application;

[0027] Figure 9 Structure diagram of a certain power system;

[0028] Figure 10 Equivalent power angle curve diagram of cutting off 109 units;

[0029] Figure 11 Schematic diagram of a unit cutting sensitivity rapid calculation system for transient stability control proposed in embodiment 2 of the present application. DETAILED DESCRIPTION

[0030] Embodiment 1

[0031] Embodiment 1 of the present application proposes a unit cutting sensitivity rapid calculation method for transient stability control, which is used to solve the technical problem that the unit cutting sensitivity information used when cutting off units for transient stability control of a power system relies on electromechanical transient simulation trajectory, resulting in long time consumption and being difficult to meet the online control requirement.

[0032] The process realized by the present application includes: firstly, grouping units by using power system basic instability scene power angle trajectory data combined with composite power angle algorithm; then, calculating comprehensive difference of cumulative unbalanced energy and decelerable area of equivalent units before and after cutting off units based on extended equal area criterion (EEAC), to form estimated value of unbalanced energy directly taken away by cutting off units; further, calculating electromagnetic power transfer amount of cut-off units by using power flow information at the time of cutting off units and power system network topology, and calculating change amount of decelerable area combined with EEAC equivalent unit power angle curve translation change assumption; finally, adding the unbalanced energy directly taken away by cutting off units and the change amount of decelerable area corresponding to power transfer to estimate stability margin change amount, and dividing the stability margin change amount by capacity of the cut-off unit to calculate unit cutting sensitivity.

[0033] Figure 1 Flowchart of a unit cutting sensitivity rapid calculation method for transient stability control proposed in embodiment 1 of the present application;

[0034] In step 1, the trajectory data of the instability scenario is obtained according to the stabilization control method of the instability scenario; the composite power angle difference is calculated using the trajectory data of the instability scenario, and the units are divided into leading units and lagging units based on the composite power angle difference;

[0035] In basic instability scenarios, firstly, based on different stability control methods, the generator inertia parameters and generator power angle, angular velocity (the difference between the actual angular velocity per unit value and the synchronous angular velocity per unit value), electromagnetic power, and mechanical power trajectory data are acquired. Then, based on the trajectory data, a composite power angle index is used to group the generator units. Figure 2 This is a flowchart of generator grouping based on the composite power angle algorithm proposed in Embodiment 1 of the present invention.

[0036] The process of obtaining trajectory data for an unstable scenario based on the stabilization control method includes:

[0037] If the stability control method is online stability control, then the generator inertia parameter data in the simulation file is read to form the generator inertia vector; the generator inertia vector is represented as:

[0038] (1)

[0039] in, For the moment of inertia of all operating generators, For the first Moment of inertia of a generator;

[0040] If the stability control method is real-time stability control, then the inertia parameter data of the operating generator is acquired through acquisition devices such as PMU and WAMS to form the generator inertia vector:

[0041] (2)

[0042] If the stability control method is online stability control, perform electromechanical transient simulation on the instability scenario, and record the time of fault occurrence with a step size of 0.01s. Until the system reaches the non-return point The state quantity trajectory data is used to form the state trajectory of each generator; the state trajectory of each generator is represented as follows:

[0043] (3)

[0044] in, For the first Power angle of generator; For the first The generator speed; For the first Electromagnetic power of the generator; the i-th generator generator mechanical power state trajectory; , the number of generators the time of fault occurrence the time of system reaching the non-return point.

[0045] Let the time of fault removal the control delay the time of generator removal control Figure 3 the relationship diagram of each time node proposed by the embodiment 1 of the present application

[0046] If the stable control mode is real-time stable control, the PMU and WAMS devices are started to collect the generator state quantity trajectory after detecting the fault occurrence, the sampling frequency is 100 Hz, and the data between the time of fault occurrence and the time of generator removal control are stored in the state quantity trajectory vector, which is the same as the expression of formula (3), but the data length is shorter.

[0047] The units are divided into the leading unit group and the lagging unit group by using the composite power angle algorithm.

[0048] If the stable control mode is online stable control, the composite power angle of each generator is expressed as:

[0049] ; (4)

[0050] wherein, the i-th generator the composite power angle of the i-th generator; the power angle at the time of system non-return point the speed at the time of system non-return point the angular velocity of the inertia center of the system the setting coefficient, which is a positive real number ;

[0051] ; (5)

[0052] If the stable control mode is real-time stable control, the composite power angle of each generator is expressed as:

[0053] ; (6)

[0054] wherein, the power angle at the time of system removal control the speed at the time of system removal control the angular velocity of the inertia center of the system

[0055] (7)

[0056] Press all generators Sort from largest to smallest to form an ordered sequence. Calculate the combined power angle difference between adjacent generators in sequence:

[0057] (8)

[0058] With difference Largest position This serves as the boundary for dividing the generator group; the first [part of the sorting sequence]... The generators are divided into advanced generator groups. The remaining generator groups are classified as lagging generator groups. Among them, advanced aircraft group It is also a group of machine cutting solutions.

[0059] In step 2, the system trajectory data from the time of the fault to the time of tripping is used as input, and the electromagnetic power angle curve and the mechanical power angle curve are determined by the extended equal area criterion. Using the electromagnetic power angle curve and the mechanical power angle curve, the acceleration area, the decelerated area and the remaining decelerated area of ​​the equivalent unit before and after tripping are calculated according to the grouping results. Then, the unbalanced energy mutation caused by tripping is calculated.

[0060] Using EEAC theory, we calculate the acceleration area, deceleration area, and remaining deceleration area of ​​the equivalent system under two conditions: whether the cut-off unit is removed or not. We then compare the differences between the two conditions to calculate the unbalanced energy mutation caused by the cut-off unit. Figure 4 This is a flowchart of the calculation of the energy mutation of the machine switching imbalance based on EEAC proposed in Embodiment 1 of the present invention.

[0061] Using the clustering results and the trajectory data of each generator as input, the equivalent system power angle, speed, electromagnetic power and mechanical power trajectory are calculated according to EEAC theory, forming electromagnetic power-power angle curves and mechanical power-power angle curves.

[0062] If the stability control method is online stability control, then the equivalent process includes: utilizing... to The trajectory data at any given time is used to calculate the work angle, angular velocity, electromagnetic power, and mechanical power of the center of inertia.

[0063] (9)

[0064] in, for Group equivalent moment of inertia; for Group equivalent rotational inertia; For Group equivalent power angle; For Group rotational speed, For Group electromagnetic power; For Group mechanical power trajectory data; For Group equivalent power angle; For Group rotational speed; For Group electromagnetic power; For Group mechanical power trajectory data;

[0065] The equivalent system power angle, angular velocity, electromagnetic power and mechanical power trajectory data from the time of fault occurrence to the time of system return point are calculated as:

[0066] ; (10)

[0067] wherein, is the inertia of the equivalent system; is the power angle of the equivalent system; is the rotational speed of the equivalent system; is the mechanical power of the equivalent system; is the electromagnetic power trajectory data of the equivalent system;

[0068] The equivalent system state trajectory is represented as:

[0069] ; (11)

[0070] If the stable control mode is real-time stable control, the equivalent process includes: substituting the trajectory data from the time of to into equations (9)-(10) to calculate the equivalent system power angle, angular velocity, electromagnetic power and mechanical power trajectory data from the time of fault occurrence to the time of generator tripping control;

[0071] Modeling the relationship between electromagnetic power, mechanical power and power angle:

[0072] ; (12)

[0073] ; (13)

[0074] wherein, is the first to-be-fitted parameter; is the second to-be-fitted parameter; is the third to-be-fitted parameter; is the fourth to-be-fitted parameter; is the fifth to-be-fitted parameter; is the sixth to-be-fitted parameter; is the equivalent system power angle, is the equivalent system electromagnetic power angle curve, is the equivalent system mechanical power angle curve;

[0075] is the equivalent system power angle, , and , is the mapping sequence, the to-be-identified parameter is calculated by using a nonlinear and least square parameter identification method ;

[0076] is the equivalent system power angle, is the starting point, is the ending point, and the extrapolated power angle prediction sequence is generated at equal intervals with a step of 0.01 rad in the interval , , the prediction sequence is substituted into the established power angle curve equation, thereby obtaining the corresponding electromagnetic power and mechanical power prediction sequences , ; the sequence elements satisfying are searched from front to back, the electromagnetic power prediction sequence corresponding to the period from the machine shedding control time to the occurrence time of the system non-return point is formed and the mechanical power prediction sequence , at this time, the corresponding power angle prediction sequence is ;

[0077] The equivalent system state quantity trajectory data and the state quantity prediction sequence data are stored into a state quantity trajectory vector, and the equivalent system state trajectory in the same form as equation (11) is obtained. Figure 5 is the equivalent power angle curve of different stable control modes proposed in embodiment 1 of the application; the equivalent power angle curve of the online stable control mode is shown in Fig. 5(a), and the equivalent power angle curve of the real-time stable control mode is shown in Fig. 5(b).

[0078] The electromagnetic power angle curve and the mechanical power angle curve are used to calculate the accelerated area, the decelerated area and the remaining decelerated area of the equivalent unit before and after the machine shedding according to the grouping result; then the process of calculating the unbalanced energy mutation caused by the machine shedding includes:

[0079] Based on the trajectory data during the fault, the rectangular method is used to calculate the accelerated area during the fault with the power angle as the independent variable and the mechanical power and the electromagnetic power as the dependent variables;

[0080] ; (14)

[0081] wherein, is the accelerated area of the equivalent system during the fault, i.e., the accumulated unbalanced energy during the fault;

[0082] Based on the trajectory data after the fault is removed, the decelerated area from the time when the fault is removed to the time when the generator is controlled to be removed is calculated by taking the power angle as the independent variable and the mechanical power and the electromagnetic power as the dependent variables using the rectangular method.

[0083] ; (15)

[0084] wherein, is the decelerated area of the equivalent system from the time when the fault is removed to the time when the generator is controlled to be removed, i.e., the unbalanced energy calculation from the time when the fault is removed to the time when the generator is controlled to be removed;

[0085] The accumulated unbalanced energy is calculated by subtracting the decelerated area after the fault is removed from the accelerated area:

[0086] ; (16)

[0087] In the formula, is the accumulated unbalanced energy from the time when the fault occurs to the time when the generator is controlled to be removed;

[0088] Based on the trajectory data after the generator is controlled to be removed, the decelerable area from the time when the generator is controlled to be removed to the time when the non-return point is calculated by taking the power angle as the independent variable and the mechanical power and the electromagnetic power as the dependent variables using the rectangular method:

[0089] ; (17)

[0090] wherein, is the decelerable area of the equivalent system from the time when the generator is controlled to be removed to the time when the non-return point is;

[0091] From the leading group of generators , any one generator is removed to form a remaining leading group of generators , and the grouping results of the remaining leading group of generators and the lagging group of generators are obtained. By taking the trajectory data of the basic instability scenario as input, the operation of step 2 above is performed to obtain:

[0092] According to the new leading group of generators and the lagging group of generators , the trajectory data of the power angle , the speed , the mechanical power , and the electromagnetic power of the equivalent system after the removed generator are calculated. The equivalent power angle curves before and after the removed generator are shown in FIG. 6.Figure 6 (a) is the pre-tripped unit equivalent power angle characteristic curve; Figure 6 (b) is the post-tripped unit equivalent power angle characteristic curve.

[0093] Cumulative unbalance energy calculation during fault:

[0094] (18)

[0095] where, is the acceleration area of the equivalent system during fault, i.e. the cumulative unbalance energy during fault

[0096] Unbalance energy calculation from fault clearing to generator tripping control:

[0097] (19)

[0098] where, is the deceleration area of the equivalent system from fault clearing to generator tripping control, i.e. the unbalance energy calculation from fault clearing to generator tripping control;

[0099] Cumulative unbalance energy calculation at generator tripping control:

[0100] (20)

[0101] where, is the cumulative unbalance energy from fault occurrence to generator tripping control;

[0102] Deceleration area calculation:

[0103] (21)

[0104] where, is the deceleration area of the equivalent system from generator tripping control to non-return point;

[0105] Calculate the change of the difference between the cumulative unbalance energy and the deceleration area of the tripped generator, i.e. the unbalance energy jump of the tripped generator:

[0106] (22)

[0107] where, is the unbalance energy jump of the tripped generator

[0108] Detect whether all generators in the leading group have been evaluated, if yes, go to step 3, otherwise, re-calculate the cumulative unbalance energy and the deceleration area of the tripped generator.

[0109] In step 3, the electromagnetic power transfer of the cut-off unit is calculated using the power flow information and power system network topology at the time of the cut-off as input, and the change in the deceleration area is calculated by assuming that the cut-off causes a shift in the equivalent unit's power angle curve. Figure 7 This is a flowchart of the calculation of the change in deceleration area considering the continuous impact of power transfer, as proposed in Embodiment 1 of the present invention.

[0110] Using power flow information at the time of generator tripping and power system network topology as input, the transient internal potential of the generator and its phase angle in synchronous coordinates are calculated.

[0111] Using power flow information at the time of generator tripping and power system network topology as input, calculate the transient internal potential of the generator and the phase angle in synchronous coordinates; expand the internal nodes of the generator and eliminate non-generator nodes to form a simplified admittance matrix.

[0112] Select any one unit from the advanced generator group for disconnection, and calculate the change in electromagnetic power of each generator and the change in electromagnetic power of the equivalent system; assume that disconnection causes the overall translation of the EEAC equivalent unit power angle curve, and calculate the change in the deceleration area.

[0113] Based on power flow information at the time of generator tripping and power system network topology data, including generators active power and reactive power ,dynamo The magnitude of the terminal voltage and phase angle ,dynamo Subtransient reactance Calculate the transient internal electromotive force of the generator Phase angle in synchronous coordinates :

[0114] ;(twenty three)

[0115] ;(twenty four)

[0116] By expanding the internal nodes of the generator and eliminating non-generator nodes, a simplified admittance matrix is ​​formed. Based on the power system network topology, the original node admittance matrix of the power system generators is established. ;

[0117] (25)

[0118] Calculate the equivalent admittance parameters of the generator:

[0119] (26)

[0120] in, For the first Equivalent admittance parameters of the generator; For the Equivalent resistance of the generator; For the Equivalent reactance of the generator;

[0121] The equivalent internal impedance admittance of the generator is merged into the original node admittance matrix Y, and the modification method is to select one generator from the generator set, and the original node number of the generator is , the newly added internal node number is , and the admittance matrix is expanded:

[0122] ; (27)

[0123] Wherein, is the original generator node self-admittance; is the newly added generator node self-admittance; is the mutual admittance between the original generator node and the newly added generator node; is the mutual admittance between the newly added generator node and the original generator node;

[0124] Detect whether all the equivalent internal impedance admittances of the generator set are merged into the original node admittance matrix, if yes, go to the next step, if not, select another generator set to perform the process;

[0125] Arbitrarily select a load Model the load as a parallel admittance, and calculate the parallel admittance:

[0126] ; (28)

[0127] Wherein, is the parallel admittance; is the active load before control; is the reactive load before control; is the node bus voltage amplitude;

[0128] Merge the equivalent admittance of the load into the original node admittance matrix ;

[0129] ; (29)

[0130] Wherein, is the original load node self-admittance;

[0131] Detect whether all the equivalent admittances of the load are merged into the original node admittance matrix, if yes, go to the next step, if not, select another load to perform the process.

[0132] The rearranged and corrected nodal admittance matrix is ​​arranged as follows: non-generator internal nodes are placed at the beginning of the admittance matrix, and generator internal nodes are placed at the end. The rearranged admittance matrix is ​​as follows:

[0133] (30)

[0134] in, This represents the rearranged admittance matrix; This represents the self-admittance submatrix between nodes within a non-generator. This represents the nodal admittance matrix of the generator. This represents the mutual admittance between nodes within a non-generator and nodes within a generator; This represents the mutual admittance between nodes within the generator and nodes outside the generator;

[0135] Performing the Kron reduction operation eliminates non-generator internal nodes, resulting in a simplified equivalent admittance matrix containing only generator internal nodes:

[0136] (31)

[0137] in, To simplify the equivalent admittance matrix;

[0138] The simplified equivalent admittance matrix is ​​separated into real and imaginary parts to form the simplified equivalent conductance matrix. With simplified equivalent susceptance matrix .

[0139] Select any one unit from the advanced turbine fleet. The process of performing the cut-off operation and calculating the changes in electromagnetic power of each generator and the equivalent system electromagnetic power includes:

[0140] The specific calculation of the change in electromagnetic power of the remaining units due to the turbine cut-off is as follows:

[0141] (32)

[0142] ;

[0143] in, For generator nodes With the disconnected generator node The synchronous torque coefficient between them; For generator nodes The internal potential; This refers to the generator terminal voltage before the unit being switched out is controlled. To simplify the equivalent susceptance matrix, the first... OK Column values, For generator pre-disturbance voltage phase angle difference, for the removed generator set node active power;

[0144] Substitute equation (32) into equation (10) to calculate the equivalent system electromagnetic power variation of the removed generator set :

[0145] ; (33)

[0146] wherein, is the variation of electromagnetic power of the i-th generator in the leading group at the time of generator removal control; is the variation of electromagnetic power of the i-th generator in the lagging group at the time of generator removal control; is the variation of electromagnetic power of the i-th generator in the leading group at the time of generator removal control; is the variation of electromagnetic power of the i-th generator in the lagging group at the time of generator removal control; is the inertia of the removed generator set ; is the sum of the inertia of the leading group and the inertia of the lagging group;

[0147] Assuming that the removal of the generator causes the overall translation of the EEAC equivalent generator power angle curve, the process of calculating the change in the deceleration area includes:

[0148] If the stability control mode is online stability control, the method for determining the equivalent system power angle curve after the removal of the generator is to translate the equivalent system electromagnetic power angle curve upward to obtain the translated equivalent system electromagnetic power angle curve :

[0149] ; (34)

[0150] wherein, is the equivalent system power angle after the removal of the generator;

[0151] is the equivalent system mechanical power angle curve after the removal of the generator;

[0152] If the stability control mode is real-time stability control, the method for determining the equivalent system power angle curve after the removal of the generator is to translate the equivalent system electromagnetic power angle curve upward to obtain the translated equivalent system electromagnetic power angle curve :

[0153] ; (35)

[0154] is the equivalent system mechanical power angle curve after the removal of the generator​ :

[0155] ; (36)

[0156] Take the power angle of the cut-off control moment as the starting point, Take the power angle of the cut-off control moment as the starting point, Take the power angle of the cut-off control moment as the starting point, and generate an extrapolated power angle sequence with equal intervals of 0.01 rad in the interval Take the power angle of the cut-off control moment as the starting point, and generate an extrapolated power angle sequence with equal intervals of 0.01 rad in the interval Take the power angle of the cut-off control moment as the starting point, and generate an extrapolated power angle sequence with equal intervals of 0.01 rad in the interval Take the power angle of the cut-off control moment as the starting point, and generate an extrapolated power angle sequence with equal intervals of 0.01 rad in the interval ;

[0157] Calculate the change in decelerable area after cutting the machine control using the trapezoidal formula:

[0158] ; (37)

[0159] Where, is the power angle of the system not returned point after the cut generator set is removed;

[0160] Detect whether all units in the leading machine group have been evaluated, if yes, go to step 4, otherwise recalculate the electromagnetic power transfer amount of the cut unit.

[0161] In step 4, the change in stability margin is calculated by the cut machine imbalance energy jump and the decelerable area change corresponding to the power transfer, and the cut machine sensitivity is calculated by dividing the cut machine amount of the cut unit.

[0162] The change in stability margin is calculated by the cut machine imbalance energy jump and the decelerable area change corresponding to the power transfer, and the cut machine sensitivity is calculated by dividing the cut machine amount of the cut unit. The specific calculation process is shown in Figure 8. Figure 8 The cut machine sensitivity calculation flowchart based on the change in stability margin is proposed in embodiment 1 of the present application;

[0163] Based on the imbalance energy jump and the decelerable area change of all units in the leading machine group calculated in steps 2 and 3, the two are added to obtain the change in stability margin:

[0164] ; (38)

[0165] Divide the stability margin change corresponding to each cut unit by the cut machine amount of the cut unit to calculate the cut machine sensitivity of all units in the leading machine group:

[0166] ; (39)

[0167] The application provides a machine tripping sensitivity rapid calculation method for transient stability control, which is suitable for rapid sensitivity calculation when an online stability control generates a strategy table or a real-time stability control generates a machine tripping scheme, and realizes rapid calculation of machine tripping sensitivity through four parts of generator set grouping based on composite power angle, machine tripping unbalanced energy jump variable calculation based on EEAC, decelerable area variable calculation considering the continuous influence of power transfer, and machine tripping sensitivity calculation based on stability margin variable. In step 1, real-time state information from power system measurement devices such as PMU / WAMS or simulation data of a basic instability scenario is taken as input, composite power angle algorithm is adopted, grouping of machine sets is carried out according to the power angle trajectory and angular velocity deviation of each machine set, and the machine set set for machine tripping sensitivity calculation is determined; in step 2, system trajectory data from the time after fault to the time of machine tripping is taken as input, the cumulative unbalanced energy and the comprehensive difference of decelerable area of equivalent machine sets before and after machine tripping are calculated according to the grouping result, and the energy directly taken away by machine tripping is formed; in step 3, the power flow information at the time of machine tripping and the power system network topology are taken as input, the electromagnetic power transfer amount of the tripped machine set is calculated, and the decelerable area variable is calculated by assuming that the power angle curve of the equivalent machine set is translated and changed due to machine tripping; in step 4, the stability margin variable is calculated by comprehensively calculating the results in steps 2 and 3, and the machine tripping sensitivity is obtained by dividing the stability margin variable by the machine tripping amount of the tripped machine set.

[0168] The machine tripping sensitivity rapid calculation method provided by the embodiment 1 of the application can accurately and rapidly calculate the stability margin variable of different machine tripping schemes based on real-time state information of the power grid, and further divide the stability margin variable by the machine tripping amount of the tripped machine set to calculate the machine tripping sensitivity.

[0169] In order to verify the technical effect realized by the application, the effectiveness of the embodiment 1 of the application is illustrated by taking a power supply system as an example. Figure 9 The structure diagram of a certain power system is shown in the figure, which comprises 11 1000kV nodes, constitutes an AC main network frame, 122 500kV nodes, 199 AC lines and 6 DC lines, and forms a complex power network. The fault scenario is that three-phase short-circuit faults are set on lines 178-152 and 124-110 in the first section at 1s, the fault duration is 0.15s, the fault line is tripped by relay protection after 0.15s, and machine tripping control is performed 0.1s after the fault line is tripped.

[0170] Firstly, the inertia parameter data of the generator and the state quantity trajectory data from the time of fault occurrence to the time of machine tripping control are recorded to form a state quantity trajectory vector, and the data time step is 0.01s.

[0171] Read the power angle and speed of the system switching control moment from the generator trajectory data, calculate the composite power angle of each generator, and sort it from large to small, then calculate the composite power angle difference between adjacent generators, the largest difference is the boundary of the generator group division, divide the generator unit into leading and lagging groups;

[0172] Based on the generator group division results and state quantity trajectory vector, the equivalent system state trajectory from fault occurrence to switching control moment is obtained by equivalent calculation according to formula (9) - formula (10);

[0173] According to the equivalent system state trajectory during the fault, the system acceleration area is calculated as 11.37;

[0174] According to the equivalent system state trajectory after fault removal, the deceleration area is calculated as -8.66;

[0175] Subtract the deceleration area from the acceleration area to get the cumulative unbalanced energy of 20.03;

[0176] Based on the equivalent system state trajectory after fault removal, the system power angle curve is obtained by curve fitting, and the equivalent system power angle characteristic prediction curve of the system non-return point is formed by extrapolation;

[0177] Based on the power angle curve prediction electromagnetic power and mechanical power prediction results, the deceleration area is calculated as 4.09;

[0178] After removing the related variables of G109, G149, G179, G190, G192 and G219 respectively, the generator trajectory data is re-grouped, equivalent and curve fitting and prediction, the cumulative unbalanced energy and deceleration area after removing different units are calculated, the cumulative unbalanced energy change and deceleration area change are added to get the switching unbalanced energy jump;

[0179] Simplify the system admittance matrix and calculate the electromagnetic power change of each generator at the switching moment, and further calculate the equivalent electromagnetic power change;

[0180] The switching causes the equivalent unit power angle curve to shift, and the deceleration area change is calculated, for example, the equivalent power angle curve of G109 removal is shown in Figure 10; Figure 10 Equivalent power angle curve for removing 109 unit;

[0181] Add the switching unbalanced energy jump and the deceleration area change to get the stability margin change, and divide it by the capacity of the removed unit to get the switching sensitivity, the calculation results are shown in Table 1.

[0182] Table 1: Switching sensitivity calculation results

[0183]

[0184] According to the analysis of the sensitivity calculation result, the error of the partial generator tripping scheme is relatively large, but the calculated sensitivity ranking is basically consistent with the actual sensitivity ranking, and the control effect of different generator tripping control measures can still be compared, wherein the average error between the calculated value and the actual value of the sensitivity of the node with high sensitivity is about 10%, the error is controlled within the allowable range, which indicates that the sensitivity calculation of the high sensitive node is accurate, and the effectiveness of the generator tripping sensitivity fast calculation method for transient stability control provided in embodiment 1 of the present application is verified.

[0185] Embodiment 2

[0186] Based on the generator tripping sensitivity calculation method for transient stability control provided in embodiment 1 of the present application, embodiment 2 of the present application further provides a generator tripping sensitivity calculation system for transient stability control, Figure 11 A schematic diagram of the generator tripping sensitivity fast calculation system for transient stability control provided in embodiment 2 of the present application is shown in the figure, and the system comprises a grouping module, a first calculation module, a second calculation module and a third calculation module;

[0187] The grouping module is used to obtain trajectory data of the instability scene according to the stability control mode of the instability scene; the composite work angle difference value is calculated by using the trajectory data of the instability scene, and the units are divided into leading groups and lagging groups based on the composite work angle difference value;

[0188] The first calculation module is used to take the system trajectory data from the fault to the generator tripping time as input, and determine the electromagnetic power angle curve and the mechanical power angle curve by using the extended equal-area criterion; the acceleration area, the deceleration area and the remaining deceleration area of the equivalent unit before and after the generator tripping are calculated according to the grouping result by using the electromagnetic power angle curve and the mechanical power angle curve; and then the imbalance energy jump caused by the generator tripping is calculated;

[0189] The second calculation module is used to take the power flow information at the generator tripping time and the power system network topology as input, calculate the electromagnetic power transfer amount of the tripped unit, and calculate the deceleration area change amount by assuming that the equivalent unit power angle curve is translated and changed due to the generator tripping;

[0190] The third calculation module is used to calculate the stability margin change amount by taking the imbalance energy jump caused by the generator tripping and the deceleration area change amount corresponding to the power transfer, and divide the generator tripping sensitivity by the generator tripping amount of the tripped unit.

[0191] The generator tripping sensitivity fast calculation system for transient stability control provided in embodiment 2 of the present application can accurately and quickly calculate the stability margin change amount of different generator tripping schemes based on the real-time state information of the power grid, and further divide the stability margin change amount by the generator tripping amount of the tripped unit to calculate the generator tripping sensitivity.

[0192] The related part of the system for calculating the generator tripping sensitivity for transient stability control provided in the embodiment 2 of the present application can refer to the detailed description of the corresponding part of the method for calculating the generator tripping sensitivity for transient stability control provided in the embodiment 1 of the present application, which will not be repeated here.

[0193] The above merely provides the embodiments of the present application but should not be used to limit the present application. Various modifications and changes can be made by those skilled in the art based on the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for calculating a generator tripping sensitivity for transient stability control, characterized in that, The method comprises the following steps: According to the instability scene, the trajectory data of the instability scene is obtained by the stability control mode, and the composite work angle difference value is calculated by using the trajectory data of the instability scene, and the units are divided into the leading group and the lagging group based on the composite work angle difference value; The system trajectory data from the fault to the time of cutting off the unit is taken as the input, and the electromagnetic power angle curve and the mechanical power angle curve are determined by using the extended equal-area criterion;The acceleration area, the deceleration area and the remaining deceleration area of the equivalent unit before and after cutting off the unit are calculated according to the grouping result by using the electromagnetic power angle curve and the mechanical power angle curve;Then, the imbalance energy mutation caused by cutting off the unit is calculated; The power flow information and the power system network topology at the time of cutting off the unit are taken as the input, the electromagnetic power transfer amount of the unit to be cut off is calculated, and the change amount of the deceleration area is calculated by assuming that the cutting off of the unit causes the equivalent unit power angle curve to shift; The stability margin change amount is calculated by the imbalance energy mutation caused by cutting off the unit and the change amount of the deceleration area corresponding to the power transfer, and the cutting off sensitivity is calculated by dividing the cutting off amount of the unit to be cut off; The acceleration area, the deceleration area and the remaining deceleration area of the equivalent unit before and after cutting off the unit are calculated according to the grouping result by using the electromagnetic power angle curve and the mechanical power angle curve; The process of calculating the imbalance energy mutation caused by cutting off the unit includes: Based on the trajectory data during the fault, the acceleration area during the fault is calculated by using the rectangular method with the power angle as the independent variable and the mechanical power and the electromagnetic power as the dependent variables; ； wherein, is the accelerated area of the equivalent system during the fault, i.e. the cumulative unbalanced energy during the fault; Based on the trajectory data after the fault is cut off, the deceleration area after the fault is cut off to the time of cutting off the unit is calculated by using the rectangular method with the power angle as the independent variable and the mechanical power and the electromagnetic power as the dependent variables; ； wherein, is the deceleration area of the equivalent system from fault removal to the generator tripping control moment, i.e. the unbalanced energy calculation from fault removal to generator tripping control The calculated acceleration area is subtracted from the deceleration area after the fault is cut off to calculate the cumulative imbalance energy: ； In the formula, is the cumulative unbalanced energy from the system fault to the time of the generator trip control. Based on the trajectory data after the cutting off control, the deceleration area from the cutting off control to the non-return point is calculated by using the rectangular method with the power angle as the independent variable and the mechanical power and the electromagnetic power as the dependent variables: ； wherein, Acut is the cut-off control to the equivalent deceleration area of the system at the moment of the point of no return. The cumulative imbalance energy and the deceleration area of the cut-off generator are calculated, and the sum of the change amount of the difference between the cumulative imbalance energy and the deceleration area before and after cutting off the unit is calculated, that is, the imbalance energy mutation caused by cutting off the unit; The process of calculating the change amount of the deceleration area by assuming that the cutting off of the unit causes the EEAC equivalent unit power angle curve to shift as a whole includes: If the stable control mode is online stable control, the method for determining the equivalent system power angle curve after the generator is tripped is as follows: the equivalent system electromagnetic power angle curve after the generator tripping control time is obtained by upward translation , and the equivalent system electromagnetic power angle curve after translation is obtained : ； in, To eliminate the equivalent system power angle after the generator unit is cut off; For the disconnected generator node The change in electromagnetic power of the equivalent system; Mechanical power is the equivalent system mechanical power power angle curve after the cutting machine control moment ; If the stable control mode is real-time stable control, the method for determining the equivalent system power angle curve after the generator is tripped is: the equivalent system electromagnetic power angle curve after the generator tripping control time is obtained by upward translation , to obtain the translated equivalent system electromagnetic power angle curve : ； Mechanical power is the equivalent system mechanical power power angle curve after the cutting machine control moment : ； wherein, is a first parameter to be fitted; is a second parameter to be fitted; is a third parameter to be fitted; is a fourth parameter to be fitted; is a fifth parameter to be fitted; is a sixth parameter to be fitted; The power angle at the moment of machine cutting control Starting from, As the endpoint, in The extrapolated work angle sequence is generated at equal intervals with a step size of 0.01 rad within the interval. Substitute the power angle sequence into the established power angle curve, and search from front to back for the first curve that satisfies the condition. The power angle value is the power angle value at the non-return point of the power angle curve of the translated equivalent system. ; The change amount of the deceleration area after the cutting off control is calculated: ； wherein, is the power angle at the point where the system after the cut generator group is not returned; is the change in the deceleration area after the generator control Until all units in the leading group are evaluated.

2. The method of claim 1, wherein, The process of obtaining the trajectory data of the instability scene according to the stability control mode of the instability scene includes: If the stability control mode is online stability control, the generator inertia parameter data in the simulation file is read to form a generator inertia vector;If the stability control mode is real-time stability control, the generator inertia parameter data of the running generator is obtained by the acquisition device to form a generator inertia vector;The generator inertia vector is represented as: ； wherein, J is the moment of inertia of the rotor of the generator, J is the moment of inertia of the rotor of the generator, J is the moment of inertia of the rotor of the generator, If the stability control mode is online stability control, the electromechanical transient simulation of the instability scene is performed to obtain the state quantity trajectory data to form the state trajectory of each generator;If the stability control mode is real-time stability control, the state quantity trajectory data of the generator is collected by the acquisition device to form the state trajectory of each generator;The state trajectory of each generator is represented as: ； Wherein, is the number of the generator unit is the generator unit power angle; is the number of the generator unit is the generator unit speed; is the number of the generator unit is the generator unit mechanical power; is the number of the generator unit is the generator unit electromagnetic power state trajectory; , is the number of the generator unit; is the time of fault occurrence; is the time of the system reaching the non-return point.

3. The method of claim 2, wherein, The process of calculating the composite work angle difference value by using the unstable scene trajectory data and grouping the units into the leading group and the lagging group based on the composite work angle difference value includes: If the stable control mode is online stability control, the composite work angle of each generator is represented as: ； wherein, is the composite power angle of the generator; is the composite power angle of the generator; is the power angle at the time of system non-return point; is the speed at the time of system non-return point; is the angular speed of the center of inertia of the system; is the setting coefficient; ； If the stable control mode is real-time stability control, the composite work angle of each generator is represented as: ； wherein, is the power angle at the system switching control moment; is the rotational speed at the system switching control moment; is the angular speed of the system inertia center; ； Sort all generators by in descending order to form an ordered sequence , and calculate the composite power angle difference between adjacent generators in turn: ； differences maximum position as a boundary of the generator group; the first generator in the sorted sequence is divided into a lead group of generators and the remaining generators are divided into a lag group of generators wherein the lead group of generators 4. The method of claim 3, wherein, The process of determining the electromagnetic power work angle curve and the mechanical power work angle curve by using the extended equal-area criterion with the system trajectory data from the fault to the time of cutting off the unit includes: If the stable control mode is online stable control, the equivalent process comprises: to calculating the power angle, angular velocity, electromagnetic power and mechanical power trajectory data of the center of inertia by using the trajectory data of the moment of time; ； wherein, is the equivalent moment of inertia of the group; is the equivalent moment of inertia of the group; is the equivalent power angle of the group; is the rotational speed of the group, is the electromagnetic power of the group; is the mechanical power trajectory data of the group; is the equivalent power angle of the group; is the rotational speed of the group; is the electromagnetic power of the group; is the mechanical power trajectory data of the group; The trajectory data of the equivalent system state from the time of the fault to the time of the system not returning is calculated, including the work angle, the angular velocity, the electromagnetic power and the mechanical power. ； wherein, is the inertia of the equivalent system; is the power angle of the equivalent system; is the rotational speed of the equivalent system; is the mechanical power of the equivalent system; is the electromagnetic power trajectory data of the equivalent system; The equivalent system state trajectory is represented as: ； If the stable control mode is real-time stable control, the equivalent process comprises: to calculating the power angle, angular velocity, electromagnetic power and mechanical power trajectory data of the equivalent system from the fault occurrence time to the generator tripping control time by using the trajectory data at the time. The relationship between the electromagnetic power, the mechanical power and the work angle is modeled. ； ； wherein, is the equivalent system power angle, is the equivalent system electromagnetic power angle curve, is the equivalent system mechanical power angle curve; With , and , as the mapping sequence, the nonlinear and least square parameter identification method is used to calculate the to-be-identified parameters ; The power angle at the moment of machine cutting control Starting from, As the endpoint, in An extrapolated power angle prediction sequence is generated at equal intervals with a step size of 0.01 rad within the interval. Substituting the predicted sequence into the established power angle curve equation, the corresponding electromagnetic power and mechanical power predicted sequences are obtained. , Search from front to back for the satisfied The sequence elements form the electromagnetic power prediction sequence for the period from the moment the tripping control occurs to the moment the system does not return. and mechanical power prediction sequence The corresponding power angle prediction sequence at this time is ; The equivalent system state trajectory data and the state quantity prediction sequence data are stored in the state quantity trajectory vector to obtain the equivalent system state trajectory.

5. The method of claim 4, wherein, The process of calculating the electromagnetic power transfer amount of the cut-off unit with the power flow information and the power system network topology at the time of cutting off the unit and assuming that the cutting off of the unit causes the work angle curve of the equivalent unit to shift to calculate the change amount of the deceleration area includes: The phase angle of the generator in the transient internal potential and the synchronous coordinate is calculated with the power flow information and the power system network topology at the time of cutting off the unit; The internal nodes of the generator are extended, and the non-generator nodes are eliminated to form a simplified admittance matrix; 6. The method of claim 5, wherein, The process of calculating the change amount of the electromagnetic power of each generator and the change amount of the electromagnetic power of the equivalent system by arbitrarily selecting a unit from the leading group to cut off includes: The phase angle of the generator in the transient internal potential and the synchronous coordinate is calculated with the power flow information and the power system network topology at the time of cutting off the unit; Based on the information of power flow at the time of generator switching and the network topology data of the power system, including the active power and the reactive power of the generator , the amplitude and the phase angle of the terminal voltage of the generator , the sub-transient reactance of the generator , the transient internal voltage of the generator and the phase angle in the synchronous coordinate are calculated: ； ； Based on the power system network topology, the power system generator original node admittance matrix is established ; ； The process of extending the internal nodes of the generator and eliminating the non-generator nodes to form a simplified admittance matrix includes: ； wherein, is the equivalent admittance parameter of the n-th generator; is the equivalent resistance of the n-th generator; is the equivalent reactance of the n-th generator; The equivalent admittance parameters of the generator are calculated: ； wherein, is the original generator node self-admittance; is the new generator node self-admittance; is the original generator node to new generator node mutual admittance; is the new generator node to original generator node mutual admittance; The admittance matrix is extended: arbitrarily chosen load modeling the load as a parallel admittance, calculating the parallel admittance: ； wherein, is the parallel admittance; is the active load at the control instant; is the reactive load at the control instant; is the node bus voltage magnitude; Combining load equivalent admittances into the original node admittance matrix ; ； wherein Y is the self-impedance of the source node. Until all the internal impedance equivalent admittances of the generator units are combined into the original node admittance matrix; Until all the load equivalent admittances are combined into the original node admittance matrix; ； wherein, represents the reordered admittance matrix; represents the self-admittance sub-matrix between non-generator internal nodes, represents the generator internal node admittance matrix, represents the mutual admittance between non-generator internal nodes and generator internal nodes; represents the mutual admittance between generator internal nodes and non-generator internal nodes. The non-generator internal nodes are arranged to the front of the admittance matrix, and the generator internal nodes are arranged to the rear, and the rearranged admittance matrix is: ； wherein to simplify the equivalent admittance matrix; The simplified equivalent admittance matrix is divided into a real part and an imaginary part to form a simplified equivalent conductance matrix and the simplified equivalent admittance matrix .

7. The method of claim 6, wherein, The non-generator internal nodes are eliminated to obtain a simplified equivalent admittance matrix containing only the generator internal nodes: The process of calculating the change amount of the electromagnetic power of each generator and the change amount of the electromagnetic power of the equivalent system by arbitrarily selecting a unit from the leading group to cut off includes: ； ； in, For generator nodes With the disconnected generator node The synchronous torque coefficient between them; For generator nodes The internal potential; This refers to the generator terminal voltage before the unit being switched out is controlled. To simplify the equivalent susceptance matrix, the first... OK Column values, For generator Voltage phase angle difference before disturbance For the disconnected generator node Active power; Further, the equivalent system electromagnetic power variation of the cut-off generator set node is calculated: ​ ； wherein, is the change in electromagnetic power of the nth generator in the lead group at the time of the generator shedding control; is the change in electromagnetic power of the nth generator in the lead group at the time of the generator shedding control; is the change in electromagnetic power of the nth generator in the lag group at the time of the generator shedding control; is the change in electromagnetic power of the nth generator in the lag group at the time of the generator shedding control; is the inertia of the nth generator group being shed; is the inertia of the nth generator group being shed; is the sum of the inertia of the lead group and the inertia of the lag group.

8. The method of claim 7, wherein, The change amount of the electromagnetic power of the remaining units caused by the cutting off of the unit is calculated, and the process is as follows: The process of calculating the stability margin change amount by the unbalanced energy sudden change amount corresponding to the power transfer and the change amount of the deceleration area and dividing the stability margin change amount by the cutting-off amount of the cut-off unit to calculate the cutting-off sensitivity includes: ； for the stable margin variation amount; for the sudden change of the unbalance energy of the cutting machine The stability margin change amount is obtained by adding the unbalanced energy sudden change amount of all the units in the leading group and the change amount of the deceleration area; ； wherein, is the cutback sensitivity for all units in the machine group; is the cutback amount for the cutback unit.

9. A system for calculating the generator tripping sensitivity for transient stability control, for implementing the method for calculating the generator tripping sensitivity for transient stability control according to any one of claims 1 to 8, characterized in that, The cutting-off sensitivity of all the units in the leading group is calculated by dividing the stability margin change amount corresponding to each cut-off unit by the cutting-off amount of the cut-off unit. The process includes a grouping module, a first calculation module, a second calculation module and a third calculation module. The grouping module is configured to obtain unstable scene trajectory data according to a stable control mode of the unstable scene; calculate a composite work angle difference value by using the unstable scene trajectory data; and divide the units into leading units and lagging units based on the composite work angle difference value. The first calculation module is configured to take system trajectory data from a fault to a machine tripping time as input, determine an electromagnetic power work angle curve and a mechanical power work angle curve by using an extended equal-area criterion; calculate an acceleration area, a deceleration area already reduced, and a remaining deceleration area of an equivalent unit before and after the machine tripping according to the grouping result by using the electromagnetic power work angle curve and the mechanical power work angle curve; and then calculate an unbalanced energy sudden change variable caused by the machine tripping. The second calculation module is configured to take power flow information and a power system network topology at the machine tripping time as input, calculate an electromagnetic power transfer amount of the tripped unit, and calculate a deceleration area change variable by assuming that the equivalent unit work angle curve is translated and changed due to the machine tripping. The third calculation module is configured to calculate a stability margin change variable by using the unbalanced energy sudden change variable caused by the machine tripping and the deceleration area change variable corresponding to the power transfer, and divide the stability margin change variable by a tripped unit amount of the tripped unit to calculate a machine tripping sensitivity.

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