A method and system for transient stability analysis of integrated energy delivery systems

Abstract

The application discloses a kind of for comprehensive energy export system transient stability analysis method and system, belong to electric power system transient angle stability technical field, method includes: based on synchronous machine-wind power-infinite system equivalent model, the self-impedance of synchronous machine, mutual impedance and its phase angle surplus are calculated, and then determine its electromagnetic power.Combining rotor motion equation and wind power, iteration is solved after fault power angle and speed;Accordingly, the existence of transient energy is calculated according to the trend of its change with power angle, to determine the critical stability point of power angle constraint and corresponding critical voltage.Finally, the critical point and critical voltage obtained are used as the quantitative index of evaluating transient stability margin, for guiding the safe and stable operation and control decision of the export system containing high proportion of new energy.The application can quickly and accurately evaluate system stability boundary, provide effective analysis tool for preventing cascading failure caused by large-scale new energy off-grid.

Description

Technical Field

[0001] This invention relates to a method and system for transient stability analysis of integrated energy transmission systems, belonging to the field of power system transient power angle stability technology. Background Technology

[0002] With the advancement of the "dual carbon" target, the proportion of new energy sources, represented by wind power and photovoltaics, in the power system continues to increase rapidly, especially the large-scale integrated energy transmission systems formed in areas rich in wind and solar resources. While these systems increase the proportion of clean energy consumption, they also bring new challenges to the transient safety and stability of the power grid. Unlike traditional pure synchronous machine systems, the dynamic behavior of the system changes profoundly after a high proportion of new energy is connected, and the instability mode exhibits complex "power angle-voltage" strong coupling characteristics. On the one hand, the power angle swing behavior of the synchronous machine after a fault still dominates the transient stability process of the system; on the other hand, the voltage dynamics of the new energy grid connection point (PCC) will affect its electromagnetic power output by changing the equivalent impedance between the synchronous machine and the system, causing the transient power angle characteristics to shift, and the traditional stability criterion based on pure sinusoidal power angle characteristics is no longer applicable.

[0003] Currently, transient power angle stability analysis of power systems mainly relies on time-domain simulation and transient energy function methods. While time-domain simulation offers high accuracy, its computational time is long, making it difficult to meet the needs of online analysis and rapid decision-making. The transient energy function method provides the possibility for rapid stability assessment, but in traditional applications, it typically assumes that the system structure remains unchanged and that the electromagnetic power is a sinusoidal function of the power angle. For integrated energy systems containing a high proportion of renewable energy sources, this assumption no longer holds. The constant power characteristics of renewable energy sources and the dynamic changes in the grid connection point voltage cause dynamic shifts in both amplitude and phase of the electromagnetic power characteristic curve of the synchronous machine after a fault, making it difficult to accurately find the critical unstable equilibrium point, thus affecting the accuracy of transient energy calculations and the reliability of critical stability point judgment.

[0004] Therefore, there is an urgent need for an analytical method that can accurately characterize the "power angle-voltage" coupling mechanism under the access of new energy sources and quickly and accurately calculate the critical stability point of the transient power angle of the system, so as to assess the stability margin of the system, guide the planning, operation and control of the power grid, prevent the chain failure caused by the large-scale disconnection of new energy sources from the grid, and ensure the safe and stable operation of the integrated energy transmission system. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and system for transient stability analysis of integrated energy transmission systems. This method can quickly and accurately calculate the transient power angle critical stability point of the system to assess the stability margin of the system, guide the planning, operation and control of the power grid, prevent cascading failures caused by large-scale disconnection of new energy sources from the grid, and ensure the safe and stable operation of integrated energy transmission systems.

[0006] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0007] In a first aspect, the present invention provides a method for transient stability analysis of an integrated energy transmission system, comprising:

[0008] Based on the pre-established equivalent model of the synchronous machine-wind power-infinite system, the self-impedance and mutual impedance of the system as viewed from the synchronous machine are calculated, and the corresponding complementary angles of self-impedance and mutual impedance are determined.

[0009] Calculate the electromagnetic power of the synchronizing machine based on the self-impedance, mutual impedance, complementary angle of self-impedance, and complementary angle of mutual impedance.

[0010] Based on the electromagnetic power, the synchronous machine rotor motion equation and the wind power input, the power angle and speed deviation at each moment after the fault are solved iteratively.

[0011] Based on the power angle, speed deviation, and post-fault system parameters, calculate the transient energy at each moment;

[0012] Based on the trend of transient energy change with power angle, determine whether the system has a minimum power angle, and determine the critical stability point constrained by power angle and the corresponding critical voltage.

[0013] The critical stability point and critical voltage are used as indicators to evaluate the transient power angle stability margin of the system, and are used to guide the safe and stable operation or control decisions of the integrated energy transmission system.

[0014] Furthermore, the electromagnetic power of the computing synchronizer is given by the following formula:

[0015] ;

[0016] in, The electromagnetic power of the synchronizing machine. and These are the self-impedance and mutual impedance of the system as viewed from the synchronizing machine. and These are the magnitudes of the self-impedance and the mutual impedance, respectively. and These are the self-impedance angles. and mutual impedance angle The complementary angle, For the current working angle, The internal potential of the synchronizing machine, The equivalent internal potential of an infinite system This is the internal potential of the synchronizing machine.

[0017] Furthermore, the iterative solution of the power angle and speed deviation at each moment after the fault includes:

[0018] Based on the electromagnetic power during the fault Changes, based on the implicit integration method to solve the differential equations of motion of the synchronous machine rotor:

[0019] ;

[0020] Get each time step incremental power angle Increment of speed deviation Its implicit integral recursive formula is:

[0021] ;

[0022] ;

[0023] ;

[0024] ;

[0025] Based on the angle of attack in the previous moment With speed deviation Iteratively update the power angle and speed deviation at the current moment.

[0026] Furthermore, the calculation of transient energy at each time step includes:

[0027] Based on the power angle at each moment after the fault With the rate of change of speed The rotor kinetic energy is calculated as follows: ;

[0028] Based on the electromagnetic power at each moment after the fault With mechanical power Integrating over the work angle, the potential energy of the system is calculated as follows: ,in, To achieve a stable equilibrium point;

[0029] The transient energy at that moment is obtained by adding the rotor kinetic energy to the system potential energy, and the calculation formula is as follows:

[0030] ;

[0031] The system potential energy expansion formula is as follows: ;

[0032] in, , , , These are the self-impedance, mutual impedance, and complementary impedance angle after the accident.

[0033] Furthermore, the determination system determines whether a minimum power angle exists. Specifically, it includes:

[0034] During the oscillation of the work angle, the potential energy of the monitoring system changes with the work angle. Changes;

[0035] If the system's potential energy has extreme points in both the positive and negative oscillations of the work angle, then the system is determined to have a minimum work angle. ;

[0036] If the system's potential energy has an extreme point only during the positive oscillation, then the system is determined to be transiently unstable in terms of power angle, and the maximum power angle at this time is recorded. This is denoted as the critical stable point constrained by the work angle.

[0037] Furthermore, the method also includes: determining the critical stability point constrained by the power angle. Then, based on the system parameters corresponding to that point, the grid connection point voltage is solved. Regarding the angle of attack Using a quartic equation in one variable, the grid connection point voltage is calculated, and the power angle-dependent critical voltage is obtained. The formula for calculating the grid connection point voltage is as follows:

[0038] ;

[0039] Among them, coefficient , , The expression is as follows:

[0040] ;

[0041] in, The equivalent reactance from the synchronous machine to the grid connection point, The equivalent impedance from the grid connection point to the infinite system. The internal potential of the synchronizing machine, For the angle of attack, , These represent the active power and reactive power fed into the system by wind power, respectively.

[0042] Secondly, the present invention provides a system for transient stability analysis of an integrated energy transmission system, for implementing the method for transient stability analysis of an integrated energy transmission system as described in any one of the preceding claims, comprising:

[0043] The impedance calculation module is used to calculate the self-impedance and mutual impedance of the system as seen from the synchronous machine, based on a pre-established equivalent model of the synchronous machine-wind power-infinite system, and to determine the corresponding complementary angles of the self-impedance angle and mutual impedance angle.

[0044] The electromagnetic power calculation module is used to calculate the electromagnetic power of the synchronous machine based on the self-impedance, mutual impedance, self-impedance angle complement, and mutual impedance angle complement.

[0045] The motion equation solving module is used to iteratively solve the power angle and speed deviation at each moment after the fault, based on the electromagnetic power, the synchronous machine rotor motion equation and the wind power fed in.

[0046] The transient energy calculation module is used to calculate the transient energy at each moment based on the power angle, speed deviation, and system parameters after the fault.

[0047] The stability point determination module is used to determine whether the system has a minimum power angle based on the trend of the transient energy changing with the power angle, and to determine the critical stability point constrained by the power angle and the corresponding critical voltage.

[0048] The evaluation module is used to use the critical stability point and critical voltage as indicators to evaluate the transient power angle stability margin of the system, and to guide the safe and stable operation or control decisions of the integrated energy transmission system.

[0049] Thirdly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the methods described above.

[0050] Fourthly, the present invention provides an electronic device, comprising:

[0051] Memory, used to store computer programs / instructions;

[0052] A processor for executing the computer program / instructions to implement the steps of any of the methods described above.

[0053] Fifthly, the present invention provides a computer program product, including a computer program / instructions that, when executed by a processor, implement the steps of any of the methods described above.

[0054] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0055] This invention provides a method and system for transient stability analysis of integrated energy transmission systems. By calculating the critical stability point of the power angle of the integrated energy transmission system, the system operator can react quickly after a fault occurs, thereby enhancing the reliability and security of the power grid. The method of this invention provides more accurate data support by precisely calculating the critical stability point of the power angle of the integrated energy transmission system under transient energy conditions, helping engineers better assess the stability of the power grid and potential risks, and improving the transient power angle stability and accuracy of the integrated energy transmission system in the face of power grid faults. The method of this invention also supports flexible adjustments of the power grid under different operating conditions and fault scenarios, which helps optimize the allocation and management of power resources, ensure the continuity and efficiency of power supply, and thus improve the economics of the power grid while ensuring the stable satisfaction of the power supply needs of the public and industrial users. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the topology of the integrated energy transmission system provided in an embodiment of the present invention;

[0057] Figure 2 This is a schematic diagram of the equivalent circuit of the integrated energy transmission system provided in an embodiment of the present invention;

[0058] Figure 3 This is a schematic diagram of the equivalent potential provided by the synchronizing machine and the system according to an embodiment of the present invention;

[0059] Figure 4 This is a graph showing the relationship between the synchronous motor power angle and the grid connection point voltage, provided in an embodiment of the present invention.

[0060] Figure 5 This is a schematic diagram illustrating the effect of the power angle swing on the offset provided in an embodiment of the present invention;

[0061] Figure 6 This is a schematic diagram of the electromagnetic power curve of the synchronous machine provided in an embodiment of the present invention;

[0062] Figure 7 This is a graph showing the influence of wind power output on the sinusoidal offset angle of electromagnetic power during transient periods, provided by an embodiment of the present invention.

[0063] Figure 8 This is a sinusoidal component amplitude curve provided in an embodiment of the present invention;

[0064] Figure 9 This is a DC component curve provided in an embodiment of the present invention;

[0065] Figure 10 This is a system energy curve diagram provided in an embodiment of the present invention;

[0066] Figure 11 This is a diagram of the actual power grid structure in a certain region of North China provided in an embodiment of the present invention;

[0067] Figure 12 This is a power angle instability curve diagram under different operating conditions of the actual power grid provided in the embodiments of the present invention. Detailed Implementation

[0068] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0069] Example 1: This example describes a method for transient stability analysis of an integrated energy transmission system, including:

[0070] Based on the pre-established equivalent model of the synchronous machine-wind power-infinite system, the self-impedance and mutual impedance of the system as viewed from the synchronous machine are calculated, and the corresponding complementary angles of self-impedance and mutual impedance are determined.

[0071] Calculate the electromagnetic power of the synchronizing machine based on the self-impedance, mutual impedance, complementary angle of self-impedance, and complementary angle of mutual impedance.

[0072] Based on the electromagnetic power, the synchronous machine rotor motion equation and the wind power input, the power angle and speed deviation at each moment after the fault are solved iteratively.

[0073] Based on the power angle, speed deviation, and post-fault system parameters, calculate the transient energy at each moment;

[0074] Based on the trend of transient energy change with power angle, determine whether the system has a minimum power angle, and determine the critical stability point constrained by power angle and the corresponding critical voltage.

[0075] The critical stability point and critical voltage are used as indicators to evaluate the transient power angle stability margin of the system, and are used to guide the safe and stable operation or control decisions of the integrated energy transmission system.

[0076] The method for transient stability analysis of a comprehensive energy transmission system provided in this embodiment involves the following steps in its application:

[0077] Establish a small-system model of synchronous machine-wind power-infinite element structure, and its integrated energy system topology diagram is shown below. Figure 1 As shown in the figure. Among them, the synchronous machine adopts the second-order classical model; the wind power is simplified to a constant power source. Taking the traditional dual-machine single-load system model as an example, the static load model can be analogized to the wind power. Therefore, the wind power output power is represented by the negative active load; the equivalent impedance of the line, transformer and infinite system only retains the reactance.

[0078] like Figure 2 As shown, The internal potential of the synchronizing machine, The equivalent internal potential of an infinite system This represents the voltage modulus on the high-voltage side of the wind power grid connection point. , These are the active power and reactive power at the wind power grid connection point, respectively. This represents the subtransient reactance value of the synchronous machine. This is the transformer reactance value. and These are the equivalent reactance values ​​of the lines shown in the diagram. It is the equivalent impedance of an infinite system. The equivalent reactance from the synchronous machine to the grid connection point, The equivalent impedance from the grid connection point to the infinite system. The negative impedance is the equivalent of the wind power output and the reactance of the branch, expressed by the grid connection point voltage and the wind power fed in. It represents the imaginary unit.

[0079] To study the transient stability characteristics of integrated energy systems, the electromagnetic power of the synchronous machine can be used. Expressed using self-impedance and mutual impedance:

[0080] ;

[0081] In the formula, and These are the self-impedance and mutual impedance of the system as viewed from the synchronizing machine. and These are the self-impedance angles. and mutual impedance angle The complementary angle is as follows:

[0082] ;

[0083] ;

[0084] After wind power is connected, the equation of motion for the synchronous machine rotor can be expressed as:

[0085] ;

[0086] in, For the angle of attack, For time, The mechanical angular velocity of the synchronous generator. For the grid synchronization angular velocity, This is the difference between the mechanical angular velocity and the synchronous angular velocity. The inertial time constant, This refers to the mechanical power of the synchronous generator.

[0087] Considering the coupling relationship between the grid connection point voltage and the synchronous motor power angle, the external power supplies of the two turbines and the wind power are considered as a single power source using Thevenin's theorem. Looking into the system from the grid connection point, the Thevenin equivalent potential represents the wind power branch voltage. The equivalent potentials provided by the synchronous motor and the system power supply are calculated separately using the superposition theorem. Figure 3 As shown, the grid connection point voltage as a function of the power angle and the wind power fed in is obtained as equation (5):

[0088] ;

[0089] in, The voltage at the grid connection point. The equivalent potential of the synchronous machine, The equivalent potential provided to the system power supply, The current supplied to the synchronous machine The current supplied to the system power supply.

[0090] Multiplying both sides of the equation by their conjugates yields:

[0091] ;

[0092] Divide both sides by By rearranging the terms, we obtain information about A quartic equation in one variable, with real high-voltage solutions:

[0093] ;

[0094] ;

[0095] Considering that the active power generated by wind power remains constant during the transient period, the low-voltage active power control link of wind power is ignored. Therefore, according to equation (6), while keeping the power transmitted from the grid connection point to the wind power collection station constant, the power angle-voltage characteristic curve can be plotted by changing the power angle value, as shown in equation (6). Figure 4 As shown. By Figure 4 It can be seen that as the grid-connected power increases, the range of solutions for the grid connection point voltage gradually decreases as the power angle expands.

[0096] A three-phase permanent short-circuit fault N-1 is set to occur at the beginning of line L2 at 0.2 seconds, and line L2 is disconnected 0.1 seconds later. Consider that the electromagnetic power of the synchronous motor and the active power output of the wind power are both 0 during the short circuit, and the voltage at the grid connection point is 0. Solve the differential equation system (3) using the implicit integration method to obtain the power angle and speed at any time t during the fault:

[0097] ;

[0098] ;

[0099] ;

[0100] ;

[0101] in, For time step, Let be the angle of attack at time t. For the increment of the work angle, This represents the increment of the rotational speed deviation. For speed deviation, Electromagnetic power during the fault, Let be the angle of attack at time t. For frequency increment, For electromagnetic power increment, It is the power frequency, specifically 50Hz.

[0102] Troubleshooting At any given moment, the wind power output jumps back to its initial value, while the power angle... No sudden changes are allowed; in this case, fault clearing is calculated according to equation (6). The voltage at the grid connection point at time is used to substitute the above variables and the system impedance after the accident into equation (1) to obtain the electromagnetic power at the time of fault clearance.

[0103] Considering that the point at which electromagnetic power equals mechanical power at critical stability corresponds to the smaller power angle, the point of stable equilibrium is considered. According to equation (7), the electrical parameters at each moment are obtained sequentially. Then, the transient energy at any moment after the fault is:

[0104] ;

[0105] In the formula, For rotor kinetic energy, For the system potential energy, , , , These are the self-impedance, mutual impedance, and complementary impedance angle after the accident. This refers to the transient energy after the fault. This represents the rate of change of rotational speed.

[0106] Because the system uses a second-order synchronous machine model that does not consider damping terms, the power angle should maintain a periodic reciprocating motion with constant amplitude swings under stable operating conditions. For a single-machine infinite bus system, the unstable equilibrium point after a fault is represented by a sine function of the static stability limit after the fault. However, in a dual-machine load system, the presence of the grid connection point means that the power angle swings will cause voltage fluctuations at the grid connection point. This causes the DC and AC components of the electromagnetic power to change over time, and the electromagnetic power curve after a fault is not a constant sine function. Therefore, it is not possible to rely on... The unstable equilibrium point after the accident is directly calculated. The electromagnetic power at each moment after the fault is cleared is calculated iteratively using equations (1), (2), (6), and (7). When the power angle swings positively during the transient period, the grid connection voltage decreases, and the amplitudes of the DC and AC components decrease monotonically while the complementary angle of the mutual impedance increases monotonically. Figure 5 As shown, the increase in the power angle causes the electromagnetic power curve to shift to the lower right. Figure 6 As shown, where and These represent the electromagnetic power before and after the accident, respectively, without considering the offset during the transient period. This represents the electromagnetic power during the actual transient period.

[0107] As wind power output is gradually increased, it can be seen that this offset becomes more pronounced as the proportion of wind power output increases. Figure 7 , Figure 8 , Figure 9 As shown. Therefore, when the high output of wind power causes the system's stable state to be constrained by voltage stability, the synchronous motor's power angle characteristics will gradually weaken, and the electromagnetic power offset will decrease.

[0108] Based on the conservation of rotor kinetic energy and system potential energy, from Figure 10 The energy curve shows that during the oscillation of the work angle, the system's potential energy increases monotonically with the increase of the absolute value of the work angle, that is, the system's potential energy increases during the oscillation of the work angle. and If a maximum potential energy exists, iterative calculations will not be possible. The time is defined as transient power angle instability, thus yielding the critical power angle stabilization mode. At this point, the critical energy is the maximum potential energy. ,lie in and ,Will Let be the critical stability point constrained by the work angle, and the corresponding This is denoted as the critical voltage constrained by the power angle.

[0109] This embodiment provides a method for transient stability analysis of integrated energy transmission systems, improving upon the shortcomings of stability analysis in new power systems, particularly enhancing the transient power angle stability and accuracy of bundled wind and thermal power transmission systems in the face of grid faults. Conventional methods require considerable time to process complex dynamics and large amounts of data, a significant drawback for power system operation and maintenance requiring rapid response. This invention introduces a rapid estimation method, enabling power system engineers to obtain key system stability indicators in a short time, crucial for timely adjustments to grid operations and prevention of potential large-scale faults. This invention utilizes optimized mathematical models and algorithms to simplify the calculation process, thereby significantly improving calculation speed without sacrificing accuracy, and meeting the application requirements of power systems in real-time environments.

[0110] In a further embodiment, to verify the accuracy of the power angle critical stability point calculation method proposed in this invention, for Figure 1 The small system model shown is analyzed. Let the baseline capacity of the small system model be... The synchronous generator has a rated power of 600MW, and its transient reactance is converted to a system per-unit value. Typical values ​​for boost transformers The system-side reactance was calculated based on the voltage level and the typical short-circuit current of 40kA. Impedance of the branch line from the wind power collection station to the grid connection point The line reactance value is determined based on the system's static power angle stability limit of the synchronous motor after a fault. and wind power static voltage stability limit The common constraint serves as the lower limit of the line transmission power. Considering that the upper limit of the synchronous machine output is 10% over-generation, wind power is replaced by constant power load, and the maximum power is taken as 500MW. The single-circuit reactance of the two lines is taken as... .

[0111] Table 1 Critical voltage and critical energy under various critical stability conditions

[0112]

[0113] As shown in Table 1, with the increase in the proportion of wind power output, the critical voltage constrained by the power angle first decreases and then increases. This is related to the replacement output of wind power and synchronous machines. When the wind power output is 0~200MW, the proportion of wind power is very small, the initial power angle of the synchronous machine is large, resulting in large transient acceleration energy and a large transient power angle swing. When the wind power output is 300~500MW, the replacement output significantly weakens the power angle characteristics of the synchronous machine, so the critical voltage shows an increasing trend at this time.

[0114] In a further embodiment, to analyze the applicability of the critical voltage criterion in a real power grid, a real power grid in North China includes integrated energy transmission systems A and B, which transmit power to the North China receiving-end main grid via UHV AC dual channels B~C and D~E. System A is a traditional energy base, and system B is a new energy base. Long-distance transmission presents a problem of static voltage stability for new energy sources. In particular, after the occurrence of the UHV AC Sanyong N-2 fault, the power angle of thermal power plants in system A fluctuates, and when the oscillation center is near system B, the voltage level of the UHV bus drops significantly, further exacerbating the voltage instability of new energy sources.

[0115] Therefore, this section takes the aforementioned power grid as an example to analyze the evolution of system instability modes under the scenario of thermal power in System A and renewable energy transmission in System B, and to verify the effectiveness of the critical voltage criterion. The fault is UHV AC N-2 in section D~E. The models of thermal power and renewable energy units are all measured models, and the low-voltage ride-through control strategy for renewable energy is ignored. The system grid structure is as follows: Figure 11 As shown.

[0116] It should be noted that the calculation of the output impedance of the new energy branch in System B is complex. This section uses the partition loss calculation method to calculate the impedance:

[0117] ;

[0118] In the formula, The partition loss of the i-th partition is calculated and read from the BPA power flow calculation. , These represent the active and reactive power of the main transformer in the i-th partition, respectively. Let be the voltage of the high-voltage bus of the main transformer in the i-th zone, assuming the per-unit voltage value is 1. Consider that during steady-state operation, the renewable energy source only generates active power, and the line... Therefore, the equivalent impedance of the new energy power generation unit in the i-th partition is... It can be approximately equivalent to:

[0119] ;

[0120] The equivalent impedance of the total new energy to B-station UHV bus is obtained by connecting the zoning impedance and the high-voltage collection branch impedance in series and parallel. By fixing different new energy output levels and adjusting the thermal power output, the critical stability conditions are calculated, and the critical voltages under each condition are shown in Table 2. The minimum voltage value of the B-station UHV bus was obtained by reading the simulation curve, which showed that the voltage was reasonable.

[0121] Table 2 Critical Voltages under Different Operating Conditions in Actual Power Grids

[0122]

[0123] Table 2 shows that when the renewable energy output of System B is between 2000-3500MW, the system is dominated by transient power angle instability, which manifests as the power angle first reaching the critical stability point and then leading to voltage instability. When the output exceeds 3500MW, it transitions to voltage instability. The power angle instability curves for each operating condition are shown in Table 2. Figure 12 As shown.

[0124] Example 2: This example provides a system for transient stability analysis of a comprehensive energy transmission system, comprising:

[0125] The impedance calculation module is used to calculate the self-impedance and mutual impedance of the system as seen from the synchronous machine, based on a pre-established equivalent model of the synchronous machine-wind power-infinite system, and to determine the corresponding complementary angles of the self-impedance angle and mutual impedance angle.

[0126] The electromagnetic power calculation module is used to calculate the electromagnetic power of the synchronous machine based on the self-impedance, mutual impedance, self-impedance angle complement, and mutual impedance angle complement.

[0127] The motion equation solving module is used to iteratively solve the power angle and speed deviation at each moment after the fault, based on the electromagnetic power, the synchronous machine rotor motion equation and the wind power fed in.

[0128] The transient energy calculation module is used to calculate the transient energy at each moment based on the power angle, speed deviation, and system parameters after the fault.

[0129] The stability point determination module is used to determine whether the system has a minimum power angle based on the trend of the transient energy changing with the power angle, and to determine the critical stability point constrained by the power angle and the corresponding critical voltage.

[0130] The evaluation module is used to use the critical stability point and critical voltage as indicators to evaluate the transient power angle stability margin of the system, and to guide the safe and stable operation or control decisions of the integrated energy transmission system.

[0131] The specific functions of each module described above are explained in the relevant content of the method in Embodiment 1, and will not be repeated here.

[0132] Example 3: This example provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the methods described in Example 1.

[0133] Example 4: This example provides an electronic device, including:

[0134] Memory, used to store computer programs / instructions;

[0135] A processor for executing the computer program / instructions to implement the steps of any of the methods described in Embodiment 1.

[0136] Example 5: This example provides a computer program product, including a computer program / instructions, which, when executed by a processor, implement the steps of the method described in any one of Examples 1.

[0137] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0138] Those skilled in the art will understand that embodiments of this disclosure can be provided as methods, systems, or computer program products. Therefore, this disclosure can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this disclosure can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0139] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0140] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0141] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0142] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and not to limit its protection scope. Although this disclosure has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this disclosure, they can still make various changes, modifications or equivalent substitutions to the specific implementation of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims.

Claims

1. A method for transient stability analysis of an integrated energy transmission system, characterized in that, include: Based on the pre-established equivalent model of the synchronous machine-wind power-infinite system, the self-impedance and mutual impedance of the system as viewed from the synchronous machine are calculated, and the corresponding complementary angles of self-impedance and mutual impedance are determined. Calculate the electromagnetic power of the synchronizing machine based on the self-impedance, mutual impedance, complementary angle of self-impedance, and complementary angle of mutual impedance. Based on the electromagnetic power, the synchronous machine rotor motion equation and the wind power input, the power angle and speed deviation at each moment after the fault are solved iteratively. Based on the power angle, speed deviation, and post-fault system parameters, calculate the transient energy at each moment; Based on the trend of transient energy change with power angle, determine whether the system has a minimum power angle, and determine the critical stability point constrained by power angle and the corresponding critical voltage. The critical stability point and critical voltage are used as indicators to evaluate the transient power angle stability margin of the system, and are used to guide the safe and stable operation or control decisions of the integrated energy transmission system.

2. The method for transient stability analysis of an integrated energy transmission system according to claim 1, characterized in that, The electromagnetic power of the computing synchronizer is given by the following formula: ； in, The electromagnetic power of the synchronizing machine. and These are the self-impedance and mutual impedance of the system as viewed from the synchronizing machine. and These are the magnitudes of the self-impedance and the mutual impedance, respectively. and These are the self-impedance angles. and mutual impedance angle The complementary angle, For the current working angle, The internal potential of the synchronizing machine, The equivalent internal potential of an infinite system This is the internal potential of the synchronizing machine.

3. The method for transient stability analysis of an integrated energy transmission system according to claim 2, characterized in that, The iterative solution for the deviations in power angle and rotational speed at each time point after the fault includes: Based on the electromagnetic power during the fault Changes, based on the implicit integration method to solve the differential equations of motion of the synchronous machine rotor: ； Get each time step incremental power angle Increment of speed deviation Its implicit integral recursive formula is: ； ； ； ； Based on the angle of attack in the previous moment With speed deviation Iteratively update the power angle and speed deviation at the current moment.

4. The method for transient stability analysis of an integrated energy transmission system according to claim 3, characterized in that, The calculation of transient energy at each time step includes: Based on the power angle at each moment after the fault With the rate of change of speed The rotor kinetic energy is calculated as follows: ; Based on the electromagnetic power at each moment after the fault With mechanical power Integrating over the work angle, the potential energy of the system is calculated as follows: ,in, To achieve a stable equilibrium point; The transient energy at that moment is obtained by adding the rotor kinetic energy to the system potential energy, and the calculation formula is as follows: ； The system potential energy expansion formula is as follows: ； in, , , , These are the self-impedance, mutual impedance, and complementary impedance angle after the accident. This refers to the transient energy after the fault. This represents the rate of change of rotational speed.

5. The method for transient stability analysis of an integrated energy transmission system according to claim 1, characterized in that, The determination system is said to have a minimum power angle. Specifically, it includes: During the oscillation of the work angle, the potential energy of the monitoring system changes with the work angle. Changes; If the system's potential energy has extreme points in both the positive and negative oscillations of the work angle, then the system is determined to have a minimum work angle. ; If the system's potential energy has an extreme point only during the positive oscillation, then the system is determined to be transiently unstable in terms of power angle, and the maximum power angle at this time is recorded. This is denoted as the critical stable point constrained by the work angle.

6. The method for transient stability analysis of an integrated energy transmission system according to claim 5, characterized in that, The method further includes: determining the critical stability point constrained by the power angle. Then, based on the system parameters corresponding to that point, the grid connection point voltage is solved. Regarding the angle of attack Using a quartic equation in one variable, the grid connection point voltage is calculated, and the power angle-dependent critical voltage is obtained. The formula for calculating the grid connection point voltage is as follows: ； Among them, coefficient , , The expression is as follows: ； in, The equivalent reactance from the synchronous machine to the grid connection point, The equivalent impedance from the grid connection point to the infinite system. The internal potential of the synchronizing machine, For the angle of attack, , These represent the active power and reactive power fed into the system by wind power, respectively.

7. A system for transient stability analysis of an integrated energy transmission system, used to implement the method for transient stability analysis of an integrated energy transmission system as described in any one of claims 1-6, characterized in that, include: The impedance calculation module is used to calculate the self-impedance and mutual impedance of the system as seen from the synchronous machine, based on a pre-established equivalent model of the synchronous machine-wind power-infinite system, and to determine the corresponding complementary angles of the self-impedance angle and mutual impedance angle. The electromagnetic power calculation module is used to calculate the electromagnetic power of the synchronous machine based on the self-impedance, mutual impedance, self-impedance angle complement, and mutual impedance angle complement. The motion equation solving module is used to iteratively solve the power angle and speed deviation at each moment after the fault, based on the electromagnetic power, the synchronous machine rotor motion equation and the wind power fed in. The transient energy calculation module is used to calculate the transient energy at each moment based on the power angle, speed deviation, and system parameters after the fault. The stability point determination module is used to determine whether the system has a minimum power angle based on the trend of the transient energy changing with the power angle, and to determine the critical stability point constrained by the power angle and the corresponding critical voltage. The evaluation module is used to use the critical stability point and critical voltage as indicators to evaluate the transient power angle stability margin of the system, and to guide the safe and stable operation or control decisions of the integrated energy transmission system.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When executed by a processor, the computer program implements the steps of the method described in any one of claims 1-6.

9. An electronic device, characterized in that, include: Memory, used to store computer programs / instructions; A processor for executing the computer program / instructions to implement the steps of the method according to any one of claims 1-6.

10. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method described in any one of claims 1-6.

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