A small signal analysis method and system suitable for high-inertia energy storage type synchronous condensers

Abstract

The application provides a small disturbance analysis method and system suitable for high-inertia energy storage type synchronous condensers, the method comprising: obtaining initial simulation data of a power system in which a set of synchronous condensers is located; setting network faults of the power system and output variables of the synchronous condenser group based on the initial simulation data; determining an oscillation mode of the synchronous condenser group relative to a converter station, and a frequency and a damping ratio of the oscillation mode according to a simulation curve of the obtained output variables; equivalencing V / f control converter stations in the initial simulation data to synchronous generators, generating a plurality of sets of equivalent simulation data, and respectively performing small disturbance calculation to determine corresponding small disturbance calculation results; and determining a small disturbance analysis result according to the frequency and the damping ratio of the oscillation mode and the small disturbance calculation results. The method and system are simple and easy to use, and are suitable for simulation analysis calculation personnel in power grid planning and operation.

Description

Technical Field

[0001] This invention relates to the field of power system simulation and analysis technology, and more specifically, to a method and system for analyzing small disturbances applicable to high-inertia energy storage synchronous condensers. Background Technology

[0002] Against the backdrop of the power industry's green and low-carbon transformation, the construction of large-scale new energy bases is increasing year by year. These large-scale new energy bases are often located far from load centers, and transmitting the collected electricity via flexible DC transmission systems has become an important application scenario in current power grid planning and operation. However, in this scenario, the new energy bases connected to the flexible DC transmission system are either isolated grids, or even if they are connected to the grid, they lack strong reactive power and inertia support due to the weakness of the local AC power grid. Therefore, configuring new synchronous condensers (SCDCs) at new energy bases has become an important measure to improve the operational risks of the AC power grid. SCDCs, by providing dynamic reactive power support, can effectively improve the system's short-circuit ratio and voltage stability, compensating for the inherent defects of new energy units in terms of lack of inertia and weak support. New SCDC technologies, such as high-inertia SCDCs based on coaxial flywheels / high-speed vacuum flywheels and energy storage SCDCs based on flywheel speed regulation / doubly fed motor speed regulation, have become important technological development directions.

[0003] In scenarios where large-scale renewable energy bases transmit power via flexible DC transmission systems, the connected AC grid typically has no power source or a weak power source. In such cases, the active power control of the flexible DC converter station on the renewable energy side can adopt a voltage-frequency control strategy, i.e., V / f control, to maintain a stable voltage amplitude and frequency at the grid connection point. The V / f control mode adopted by the flexible DC converter station can be considered the most ideal grid-type control method.

[0004] Prony analysis is an important technique in signal processing. It is commonly used for dynamic simulation and stability studies of power systems. Meanwhile, small-disturbance stability analysis is another important method for dynamic analysis of power systems. The results of the two methods can corroborate each other, but differences exist. Generally, under the same oscillation mode, the damping ratio obtained from Prony analysis is usually smaller than that obtained from small-disturbance analysis.

[0005] Although there are relatively mature small-disturbance analysis methods for existing synchronous condensers, most commercial power system analysis software currently lacks the function of performing small-disturbance analysis on the oscillation modes between flexible DC converter stations using V / f control mode and synchronous condensers configured in renewable energy plants. This hinders the research on the large-grid safety and stability of existing or future flexible DC converter stations and synchronous condensers configured in renewable energy plants under V / f control mode, and impedes the development of the technology for renewable energy plants with synchronous condensers to collect power and transmit it through flexible DC transmission systems in the field of large-grid safety and stability analysis. Summary of the Invention

[0006] To address the technical problem that existing power system analysis software lacks the capability to perform small-disturbance analysis on the oscillation modes between flexible DC converter stations and synchronous condensers configured in new energy power plants under V / f control mode, this invention provides a small-disturbance analysis method and system applicable to high-inertia energy storage synchronous condensers. This method is used in scenarios where new energy power is collected and transmitted through a flexible DC transmission system, simulating a small-disturbance analysis scenario between a group of synchronous condensers and a flexible DC converter station using V / f control, when the flexible DC converter station employs V / f control mode and the new energy power plant is equipped with synchronous condensers, to identify the oscillation modes between the two.

[0007] According to one aspect of the present invention, the present invention provides a method for small disturbance analysis applicable to high-inertia energy storage synchronous condensers, the method comprising: A set of initial simulation data for a power system in which synchronous condensers are located is obtained. The power system includes a new energy power station equipped with synchronous condensers and a complete flexible DC transmission system. The complete flexible DC transmission system includes a flexible DC converter station using V / f control mode. The synchronous condenser group of the new energy power station and the AC bus of the flexible DC converter station using V / f control mode are located in the same synchronous AC network. The initial simulation data satisfies the convergence of power flow calculation and can perform disturbance-free transient stability calculation normally. Based on the initial data used in the simulation, the network faults of the power system and the output variables of the synchronous condenser group are set; After the transient stability calculation involving the network fault is completed, the simulation curve of the output variable is obtained, and the first oscillation mode of the synchronous condenser group relative to the flexible DC converter station using V / f control mode, as well as the frequency and damping ratio of the first oscillation mode, are determined based on the simulation curve. The flexible DC converter station using V / f control mode in the initial data for simulation is equated to a synchronous generator, and several sets of equivalent data for simulation are generated. Based on at least one set of simulation equivalent data that satisfies the convergence of power flow calculation and can normally perform disturbance-free transient stability calculation, small disturbance calculation is performed respectively to determine the corresponding small disturbance calculation results, wherein the small disturbance results include a second oscillation mode, and the oscillation frequency and damping ratio of the second oscillation mode; Based on the frequency and damping ratio of the first oscillation mode, and the frequency and damping ratio of the second oscillation mode corresponding to the first oscillation mode, the small disturbance analysis results between the synchronous condenser group and the flexible DC converter station using the V / f control mode are determined.

[0008] According to another aspect of the present invention, the present invention provides a small disturbance analysis system suitable for high-inertia energy storage synchronous condensers, the system comprising: The data acquisition module is used to acquire a set of initial simulation data for the power system where the synchronous condensers are located. The power system includes a new energy power station equipped with synchronous condensers and a complete flexible DC transmission system. The complete flexible DC transmission system includes a flexible DC converter station using V / f control mode. The synchronous condenser group of the new energy power station and the AC bus of the flexible DC converter station using V / f control mode are located in the same synchronous AC network. The initial simulation data satisfies the convergence of power flow calculation and can perform disturbance-free transient stability calculation normally. The initial setup module is used to set the network faults of the power system and the output variables of the synchronous condenser group based on the initial data for simulation. The first analysis module is used to obtain the simulation curve of the output variable after the transient stability calculation containing the network fault is completed, and to determine the first oscillation mode of the synchronous condenser group relative to the flexible DC converter station using V / f control mode, as well as the frequency and damping ratio of the first oscillation mode, based on the simulation curve. The equivalent data module is used to convert the flexible DC converter station using the V / f control mode in the initial data for simulation into a synchronous generator, and generate several sets of equivalent data for simulation. The second analysis module is used to perform small disturbance calculations on at least one set of simulation equivalent data that meet the requirements of power flow calculation convergence and can normally perform disturbance-free transient stability calculations, and to determine the corresponding small disturbance calculation results. The small disturbance results include a second oscillation mode, as well as the oscillation frequency and damping ratio of the second oscillation mode. The result output module is used to determine the small disturbance analysis results between the synchronous condenser group of the new energy power station and the flexible DC converter station using the V / f control mode, based on the frequency and damping ratio of the first oscillation mode and the frequency and damping ratio of the second oscillation mode corresponding to the first oscillation mode.

[0009] According to another aspect of the present invention, a computer-readable storage medium is provided, the storage medium storing a computer program that, when executed by a processor, implements the methods described in any of the above aspects of the present invention.

[0010] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising: a processor; a memory for storing executable instructions of the processor; the processor being configured to read the executable instructions from the memory and execute the instructions to implement the method described in any of the preceding aspects of the present invention.

[0011] The present invention discloses a method and system for small disturbance analysis applicable to high-inertia energy storage synchronous condensers. The method includes: acquiring a set of initial simulation data for a power system where the synchronous condenser is located; setting network faults and output variables of the synchronous condenser group based on the initial simulation data; after the transient stability calculation including the network fault is completed, acquiring the simulation curve of the output variables, and determining the first oscillation mode of the synchronous condenser group relative to a flexible DC converter station using V / f control mode, as well as the frequency and damping ratio of the first oscillation mode, based on the simulation curve; equating the flexible DC converter station using V / f control mode in the initial simulation data to a synchronous generator, generating several sets of equivalent simulation data; performing small disturbance calculations on at least one set of equivalent simulation data that satisfies power flow calculation convergence and can normally perform disturbance-free transient stability calculations, and determining the corresponding small disturbance calculation results; and performing small disturbance analysis based on the frequency and damping ratio of the first oscillation mode and the small disturbance calculation results. The described method and system, by performing equivalent modeling of a flexible DC converter station employing V / f control mode and comparing the small-disturbance analysis results obtained after modeling with the Prony analysis results of transient stability simulation curves, can effectively simulate the small-disturbance oscillation modes between a high-inertia energy storage synchronous condenser and a V / f-controlled flexible DC converter station. The determined small-disturbance analysis results can guide the safe and stable operation of the system. This method is simple and easy to implement, suitable for simulation analysis and calculation personnel in power grid planning and operation. Attached Figure Description

[0012] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures: Figure 1 This is a flowchart of a small disturbance analysis method applicable to high-inertia energy storage synchronous condensers according to a preferred embodiment of the present invention; Figure 2 A geographical wiring diagram based on initial simulation data according to a preferred embodiment of the present invention; Figure 3This is a schematic diagram of the power angle curve of any synchronous condenser in a synchronous condenser group of a new energy power station according to a preferred embodiment of the present invention. Figure 4 This is a screenshot of the Prony analysis results of the power angle curve of any synchronous condenser in a synchronous condenser group of a new energy power station according to a preferred embodiment of the present invention. Figure 5 This is a schematic diagram of a geographic wiring diagram based on equivalent data for simulation according to a preferred embodiment of the present invention; Figure 6 This is a screenshot of the results of a small disturbance analysis based on a set of equivalent simulation data according to a preferred embodiment of the present invention. Figure 7 This is a screenshot of the results of a small disturbance analysis based on another set of equivalent simulation data according to a preferred embodiment of the present invention. Figure 8 This is a schematic diagram of a small disturbance analysis system suitable for high-inertia energy storage synchronous condensers according to a preferred embodiment of the present invention. Figure 9 This is a schematic diagram of the structure of an electronic device according to a preferred embodiment of the present invention. Detailed Implementation

[0013] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0014] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0015] Exemplary methods Figure 1 This is a flowchart illustrating a small-disturbance analysis method suitable for high-inertia energy storage synchronous condensers according to a preferred embodiment of the present invention. Figure 1 As shown, the small disturbance analysis method for high inertia energy storage synchronous condensers described in this preferred embodiment starts from step 101.

[0016] In step 101, a set of initial simulation data for the power system where the synchronous condenser is located is obtained. The power system includes a new energy power station equipped with synchronous condensers and a complete flexible DC transmission system. The complete flexible DC transmission system includes a flexible DC converter station using V / f control mode. The synchronous condenser group of the new energy power station and the AC bus of the flexible DC converter station using V / f control mode are located in the same synchronous AC network. The initial simulation data satisfies the convergence of power flow calculation and can perform disturbance-free transient stability calculation normally.

[0017] In this preferred embodiment, the initial data used for simulation satisfies the convergence of power flow calculation and can perform normal, disturbance-free transient stability calculation, including reasonable power flow calculation results, no errors, over-limit alarms, or action information in the electromechanical transient simulation software log, and no high / low voltage ride-through or grid disconnection of new energy sources.

[0018] Figure 2 A geographical wiring diagram based on initial simulation data according to a preferred embodiment of the present invention. Figure 2 As shown, the power system of this preferred embodiment has four renewable energy power stations: Renewable Energy Station 1, Renewable Energy Station 2, Renewable Energy Station 3, and Renewable Energy Station 4. Each renewable energy power station collects power from its own substation (in order: Substation 1, Substation 2, Substation 3, Substation 4) and gathers it at Substation 1. Each of the four renewable energy power stations is equipped with a synchronous condenser. Substation 1 is connected to the AC bus of the flexible DC converter station via four AC interconnection lines, and transmits the collected power through the flexible DC transmission system. The flexible DC converter station is a rectifier station, employing a V / f control mode, i.e., constant AC voltage control on the rectifier side. For the obtained data containing... Figure 2 The initial data used in the power system simulation by China Information showed normal power flow calculation results, flat and unfluctuated transient stability calculation curves, no errors, over-limit alarms, or action information in the logs, and no high / low voltage ride-throughs or grid disconnections from renewable energy sources.

[0019] In step 102, the network faults of the power system and the output variables of the synchronous condenser group are set based on the initial data for simulation.

[0020] Preferably, the network faults of the power system and the output variables of the synchronous condenser group are set based on the initial data for the simulation, wherein: Setting up network faults in the power system includes: The faulty line is set as any AC line among the outgoing lines of the AC bus of the flexible DC converter station using V / f control mode. The fault location is set to the side closest to the AC bus of the flexible DC converter station using V / f control mode; Set the fault type to either asymmetrical short circuit fault or three-phase short circuit fault; Set the fault duration to 0.5 cycles to 10 cycles; The output variables are set to the power angle of any synchronous condenser in the synchronous condenser group and the positive sequence voltage of the bus near it.

[0021] In this preferred embodiment, a single-phase short-circuit ground fault with a duration of 0.01s (i.e. 0.5 cycles) is set on one of the four AC tie lines between substation 1 and converter station AC bus, and the power angle and bus voltage of any synchronous condenser in the synchronous condenser group are set as output variables.

[0022] In step 103, after the transient stability calculation including the network fault is completed, the simulation curve of the output variable is obtained, and the first oscillation mode of the synchronous condenser group relative to the flexible DC converter station using V / f control mode, as well as the frequency and damping ratio of the first oscillation mode, are determined based on the simulation curve.

[0023] Preferably, determining the first oscillation mode of the synchronous condenser group relative to the flexible DC converter station using V / f control mode, as well as the frequency and damping ratio of the first oscillation mode, based on the simulation curve includes: Using the positive sequence voltage curve of the bus near the synchronous condenser group as the candidate curve, the power angle curve of any synchronous condenser in the synchronous condenser group is preferentially retrieved for Prony analysis to determine the first oscillation mode of the synchronous condenser group relative to the flexible DC converter station using V / f control mode, as well as the frequency and damping ratio of the first oscillation mode.

[0024] Figure 3 This is a schematic diagram of the power angle curve of any synchronous condenser in a synchronous condenser group of a new energy power station according to a preferred embodiment of the present invention. Figure 3 The diagram shows the power angle curve of a synchronous condenser within the new energy power station 1 connected to substation 1. From... Figure 3 It can be seen that the amplitude of the camera adjustment angle curve decreases significantly after several fluctuations.

[0025] Figure 4 This is a screenshot of the Prony analysis results of the power angle curve of any synchronous condenser in a synchronous condenser group at a new energy power station, according to a preferred embodiment of the present invention. Figure 4 As shown, for Figure 3 Using the Prony analysis tool, the power angle curve can identify the first oscillation mode of the flexible DC converter station with V / f control mode relative to the synchronous condenser group of the new energy power station. The corresponding frequency is 1.4205Hz and the damping ratio is 0.1121.

[0026] In step 104, the flexible DC converter station using V / f control mode in the initial simulation data is equated to a synchronous generator, and several sets of equivalent simulation data are generated.

[0027] Preferably, the flexible DC converter station using V / f control mode in the initial simulation data is equated to a synchronous generator, generating several sets of equivalent simulation data, including: The entire set of flexible DC transmission system data in the initial simulation data is invalidated to generate the first data; In the power flow calculation data of the initial data used in the simulation, the AC bus of the converter station is set as the slack node, and the voltage amplitude and phase angle of the slack node are set as constant values ​​to generate the second data; When the AC bus of the flexible DC converter station using V / f control mode is equivalent to a synchronous generator, several sets of third data are generated in the transient stability calculation data of the initial data used in the simulation by configuring the values ​​of the parameters in the classic generator model. Based on the first data, the second data, and each group of third data, equivalent simulation data for the corresponding group is generated.

[0028] Preferably, the entire set of flexible DC transmission system data in the initial simulation data is invalidated to generate the first data, including: In the power flow calculation data of the initial data used in the simulation, the flexible DC converter, converter transformer, DC line and other auxiliary components in the entire flexible DC transmission system are all changed to an invalid state.

[0029] Preferably, in the power flow calculation data of the initial data used for simulation, the AC bus of the converter station is set as a slack node, and the voltage amplitude and phase angle of the slack node are set to constant values ​​to generate the second data, wherein: The voltage amplitude is set to 1.0 pu; The phase angle is set to 0°.

[0030] Preferably, when the AC bus of the flexible DC converter station using V / f control mode is equivalent to a synchronous generator, several sets of third data are generated in the transient stability calculation data of the initial data used in the simulation by configuring the values ​​of parameters in the classic generator model, wherein: The kinetic energy EMWS of the synchronous generator ranges from 50,000 to 999,999, and the unit of EMWS is MW*second; The per-unit parameter benchmark value of the motor is taken as the local capacity of the synchronous generator or the benchmark capacity of the power system; Direct-axis transient reactance It takes a value between 0.00001 and 0.01 pu.

[0031] In this preferred embodiment, two sets of equivalent simulation data are generated. The first set of equivalent simulation data for each set is obtained by invalidating the entire set of flexible DC transmission system data in the initial simulation data. The second set of data is obtained by setting the AC bus of the converter station as a slack node in the power flow calculation data of the initial simulation data, and setting the voltage amplitude of the slack node to 1.0 pu and the phase angle to 0°. In the third set of data, the per-unit parameter reference values ​​of the motor are all taken as 100MW of synchronous generator capacity and direct-axis transient reactance. Both are set to 0.0001 pu, the difference being that EMWS in one group is 50000 MW*s, while EMWS in the other group is 900000 MW*s.

[0032] Will Figure 2 The rectifier station in the middle is equivalent to the electrical system wiring after the synchronous motor, such as... Figure 5 As shown.

[0033] In this preferred embodiment, power flow calculation and undisturbed transient stability calculation are performed based on two sets of equivalent simulation data, respectively. Both calculations satisfy power flow convergence, and the undisturbed transient stability calculation is normal.

[0034] In step 105, small disturbance calculations are performed on at least one set of simulation equivalent data that meet the requirements of power flow calculation convergence and can perform normal undisturbed transient stability calculation, and the corresponding small disturbance calculation results are determined. The small disturbance results include a second oscillation mode, as well as the oscillation frequency and damping ratio of the second oscillation mode.

[0035] In this preferred embodiment, linearization and eigenvalue calculation are sequentially performed on the two sets of equivalent simulation data using a small disturbance analysis tool. The generator kinetic energy (EMWS) is calculated at 50000 MW*seconds, as shown in the following figure. Figure 6 As shown, there exists an oscillation mode of a set of equivalent generator PCCs (equivalent to a flexible DC converter station using V / f control mode) relative to the synchronous condenser group of the new energy power station, with a corresponding frequency of 1.629Hz and a damping ratio of 0.133. The calculated result of the generator kinetic energy EMWS being taken as 900000MW*seconds is as follows... Figure 7 As shown, there exists an oscillation mode of a set of equivalent generator PCC relative to the synchronous condenser group of the new energy power station, with a corresponding frequency of 1.586Hz and a damping ratio of 0.148.

[0036] In step 106, based on the frequency and damping ratio of the first oscillation mode and the frequency and damping ratio of the second oscillation mode corresponding to the first oscillation mode, the small disturbance analysis results between the synchronous condenser group and the flexible DC converter station using the V / f control mode are determined.

[0037] Preferably, based on the frequency and damping ratio of the first oscillation mode, and the frequency and damping ratio of the second oscillation mode corresponding to the first oscillation mode, the small disturbance analysis results between the synchronous condenser group and the flexible DC converter station using V / f control mode are determined, including: Calculate the frequency of the second oscillation mode corresponding to the first oscillation mode and the frequency of the first oscillation mode to obtain the frequency deviation; Calculate the damping ratio of the second oscillation mode corresponding to the first oscillation mode and the damping ratio of the first oscillation mode to obtain the damping ratio deviation; When the frequency deviation and the damping ratio deviation meet the set small disturbance analysis validity criteria, the second oscillation mode corresponding to the frequency deviation and the damping ratio deviation is determined, and the frequency and damping ratio of the second oscillation mode are the small disturbance analysis results between the synchronous condenser group and the flexible DC converter station using the V / f control mode. The small disturbance analysis validity criteria are that the frequency deviation is less than the defined frequency deviation threshold and the damping ratio deviation is less than the defined damping ratio deviation threshold.

[0038] Preferably, the frequency deviation threshold is 0.2 Hz and the damping ratio deviation threshold is 0.1 Hz.

[0039] In this preferred embodiment, when the frequency deviation threshold is 0.2Hz and the damping ratio deviation threshold is 0.1, if the first oscillation mode is the oscillation mode of the flexible DC converter station using V / f control mode relative to the synchronous condenser group of the new energy power station, then after equating the flexible DC converter station using V / f control mode to a synchronous generator, its corresponding second oscillation mode is the oscillation mode of the equivalent generator PCC relative to the synchronous condenser group of the new energy power station. Therefore, the deviations of the frequency and damping ratio of the two sets of second oscillation modes from the frequency and damping ratio of the first oscillation mode are calculated respectively, and the results are shown in Table 1.

[0040] Table 1

[0041] As shown in Table 1, based on the small disturbance calculation results obtained using two sets of equivalent simulation data, it can be seen that the damping ratio obtained by the small disturbance analysis is improved in both cases compared with the Prony analysis results. This is consistent with the general rule in theoretical analysis that the damping ratio value in the Prony analysis results is smaller than the damping ratio value in the small disturbance calculation results under the same oscillation mode. Comparing the results of the two EMWS values, it can also be found that the larger the EMWS value, the smaller the deviation of the small disturbance oscillation frequency, and the greater the improvement of the damping ratio. Furthermore, when the generator kinetic energy EMWS value is 50000MW*second, the frequency deviation exceeds 0.2Hz, while when the generator kinetic energy is 900000MW*second, the oscillation frequency deviation is less than 0.2Hz, and the damping ratio deviation is less than 0.1, satisfying the validity criterion of the small disturbance analysis. It can be considered that the small disturbance calculation results generated by the equivalent simulation data when the generator kinetic energy is 900000MW*second are the small disturbance analysis results between the synchronous condenser group of the new energy power station and the flexible DC converter station using the V / f control mode.

[0042] The small disturbance analysis method for high-inertia energy storage synchronous condensers described in this preferred embodiment calculates small disturbances by equivalently modeling the V / f control mode converter station as a synchronous generator, and then comparing the small disturbance calculation results with the Prony analysis results of the transient stability simulation curves to determine the small disturbance analysis results of the V / f control mode converter station relative to the synchronous condenser connected to the renewable energy power station. This achieves effective simulation of the small disturbance oscillation mode between the high-inertia energy storage synchronous condenser and the V / f control flexible DC converter station, and the simulation results can guide the safe and stable operation of the system. This method is simple and easy to implement, suitable for simulation analysis and calculation personnel in power grid planning and operation.

[0043] Exemplary System Figure 8 This is a schematic diagram of a small disturbance analysis system suitable for high-inertia energy storage synchronous condensers according to a preferred embodiment of the present invention. Figure 8 As shown, the small disturbance analysis system 200 for high-inertia energy storage synchronous condensers according to this preferred embodiment includes: The data acquisition module 201 is used to acquire a set of initial simulation data for the power system where the synchronous condensers are located. The power system includes a new energy power station equipped with synchronous condensers and a complete flexible DC transmission system. The complete flexible DC transmission system includes a flexible DC converter station using V / f control mode. The synchronous condenser group of the new energy power station and the AC bus of the flexible DC converter station using V / f control mode are located in the same synchronous AC network. The initial simulation data satisfies the convergence of power flow calculation and can perform disturbance-free transient stability calculation normally. Initial setup module 202 is used to set the network faults of the power system and the output variables of the synchronous condenser group based on the initial data for simulation. The first analysis module 203 is used to obtain the simulation curve of the output variable after the transient stability calculation of the included network fault is completed, and to determine the first oscillation mode of the synchronous condenser group relative to the flexible DC converter station using V / f control mode, as well as the frequency and damping ratio of the first oscillation mode, based on the simulation curve. Equivalent data module 204 is used to convert the flexible DC converter station using V / f control mode in the initial data for simulation into a synchronous generator, and generate several sets of equivalent data for simulation. The second analysis module 205 is used to perform small disturbance calculations on at least one set of simulation equivalent data that meet the requirements of power flow calculation convergence and can normally perform disturbance-free transient stability calculation, and to determine the corresponding small disturbance calculation results. The small disturbance results include a second oscillation mode, and the oscillation frequency and damping ratio of the second oscillation mode. The result output module 206 is used to determine the small disturbance analysis results between the synchronous condenser group and the flexible DC converter station using the V / f control mode, based on the frequency and damping ratio of the first oscillation mode and the frequency and damping ratio of the second oscillation mode corresponding to the first oscillation mode.

[0044] The small disturbance analysis system for high-inertia energy storage synchronous condensers described in this preferred embodiment and the small disturbance analysis method for high-inertia energy storage synchronous condensers follow the same steps as the method described above. First, the converter station in V / f control mode is modeled as an equivalent synchronous generator. Then, small disturbance calculations are performed. Finally, the small disturbance calculation results are compared with the Prony analysis results of the transient stability simulation curve to determine the small disturbance analysis results of the synchronous condenser connected to the new energy power station in V / f control mode. The technical effects achieved are also the same, and will not be elaborated further here.

[0045] Exemplary electronic devices Figure 9 This is a schematic diagram of the structure of an electronic device according to a preferred embodiment of the present invention. Figure 9 As shown, the electronic device includes one or more processors 301 and memory 302.

[0046] The processor 301 may be a central processing unit (CPU) or other form of processing unit with data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0047] The memory 302 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 301 may execute the program instructions to implement the small disturbance analysis method for high-inertia energy storage synchronous condensers and / or other desired functions as described in the various embodiments disclosed above. In one example, the electronic device may also include an input device 303 and an output device 304, these components being interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0048] In addition, the input device 303 may also include, for example, a keyboard, a mouse, etc.

[0049] The output device 304 can output various information to the outside. The output device 304 may include, for example, a display, a speaker, a printer, and a communication network and its connected remote output devices, etc.

[0050] Of course, for the sake of simplicity, Figure 9 Only some of the components of the electronic device relevant to this disclosure are shown, omitting components such as buses, input / output interfaces, etc. In addition, the electronic device may include any other suitable components depending on the specific application.

[0051] Exemplary computer program products and computer-readable storage media In addition to the methods and apparatus described above, embodiments of this disclosure may also be computer program products comprising computer program instructions that, when executed by a processor, cause the processor to perform the steps in the small disturbance analysis method for high-inertia energy storage synchronous condensers according to various embodiments of this disclosure as described in the "Exemplary Methods" section of this specification.

[0052] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of this disclosure. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on a user's computing device, partially on a user's computing device, as a standalone software package, partially on a user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0053] Furthermore, embodiments of this disclosure may also be computer-readable storage media storing computer program instructions that, when executed by a processor, cause the processor to perform the steps in the small disturbance analysis method for high-inertia energy storage synchronous condensers according to various embodiments of this disclosure as described in the "Exemplary Methods" section above.

[0054] The computer-readable storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof.

[0055] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0056] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For system embodiments, since they largely correspond to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0057] The block diagrams of devices, apparatuses, devices, and systems disclosed herein are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0058] The apparatus and methods of this disclosure may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods of this disclosure are not limited to the order specifically described above unless otherwise specifically stated. Furthermore, in some embodiments, this disclosure may also be implemented as a program recorded on a recording medium, the program including machine-readable instructions for implementing the methods according to this disclosure. Thus, this disclosure also covers recording media storing programs for performing the methods according to this disclosure.

[0059] It should also be noted that in the apparatus, devices, and methods of this disclosure, the components or steps are decomposable and / or recombinable. Such decomposition and / or recombination should be considered equivalent to the present disclosure. The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0060] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A method for analyzing small disturbances applicable to high-inertia energy storage synchronous condensers, characterized in that, The method includes: A set of initial simulation data for a power system in which synchronous condensers are located is obtained. The power system includes a new energy power station equipped with synchronous condensers and a complete flexible DC transmission system. The complete flexible DC transmission system includes a flexible DC converter station using V / f control mode. The synchronous condenser group of the new energy power station and the AC bus of the flexible DC converter station using V / f control mode are located in the same synchronous AC network. The initial simulation data satisfies the convergence of power flow calculation and can perform disturbance-free transient stability calculation normally. Based on the initial data used in the simulation, the network faults of the power system and the output variables of the synchronous condenser group are set; After the transient stability calculation involving the network fault is completed, the simulation curve of the output variable is obtained, and the first oscillation mode of the synchronous condenser group relative to the flexible DC converter station using V / f control mode, as well as the frequency and damping ratio of the first oscillation mode, are determined based on the simulation curve. The flexible DC converter station using V / f control mode in the initial data for simulation is equated to a synchronous generator, and several sets of equivalent data for simulation are generated. Based on at least one set of simulation equivalent data that satisfies the convergence of power flow calculation and can normally perform disturbance-free transient stability calculation, small disturbance calculation is performed respectively to determine the corresponding small disturbance calculation results, wherein the small disturbance results include a second oscillation mode, and the oscillation frequency and damping ratio of the second oscillation mode; Based on the frequency and damping ratio of the first oscillation mode, and the frequency and damping ratio of the second oscillation mode corresponding to the first oscillation mode, the small disturbance analysis results between the synchronous condenser group and the flexible DC converter station using the V / f control mode are determined.

2. The method according to claim 1, characterized in that, Based on the initial data used in the simulation, the network faults of the power system and the output variables of the synchronous condenser group are set, wherein: Setting up network faults in the power system includes: The faulty line is set as any AC line among the outgoing lines of the AC bus of the flexible DC converter station using V / f control mode. The fault location is set to the side closest to the AC bus of the flexible DC converter station using V / f control mode; Set the fault type to either asymmetrical short circuit fault or three-phase short circuit fault; Set the fault duration to 0.5 cycles to 10 cycles; The output variables are set to the power angle of any synchronous condenser in the synchronous condenser group and the positive sequence voltage of the bus near it.

3. The method according to claim 2, characterized in that, Based on the simulation curves, the first oscillation mode of the synchronous condenser group relative to the flexible DC converter station using V / f control mode is determined, along with the frequency and damping ratio of the first oscillation mode, including: Using the positive sequence voltage curve of the bus near the synchronous condenser group as the candidate curve, the power angle curve of any synchronous condenser in the synchronous condenser group is preferentially retrieved for Prony analysis to determine the first oscillation mode of the synchronous condenser group relative to the flexible DC converter station using V / f control mode, as well as the frequency and damping ratio of the first oscillation mode.

4. The method according to claim 1, characterized in that, The flexible DC converter station using V / f control mode in the initial simulation data is equated to a synchronous generator, generating several sets of equivalent simulation data, including: The entire set of flexible DC transmission system data in the initial simulation data is invalidated to generate the first data. In the power flow calculation data of the initial data used in the simulation, the AC bus of the converter station is set as the slack node, and the voltage amplitude and phase angle of the slack node are set as constant values ​​to generate the second data; When the AC bus of the flexible DC converter station using V / f control mode is equivalent to a synchronous generator, several sets of third data are generated in the transient stability calculation data of the initial data used in the simulation by configuring the values ​​of the parameters in the classic generator model. Based on the first data, the second data, and each group of third data, equivalent simulation data for the corresponding group is generated.

5. The method according to claim 4, characterized in that, The entire set of flexible DC transmission system data in the initial simulation data is invalidated to generate the first data, including: In the power flow calculation data of the initial data used in the simulation, the flexible DC converter, converter transformer, DC line and other auxiliary components in the entire flexible DC transmission system are all changed to an invalid state.

6. The method according to claim 4, characterized in that, In the power flow calculation data of the initial data used in the simulation, the AC bus of the converter station is set as the slack node, and the voltage amplitude and phase angle of the slack node are set to constant values ​​to generate the second data, wherein: The voltage amplitude is set to 1.0 pu; The phase angle is set to 0°.

7. The method according to claim 1, characterized in that, When the AC bus of a flexible DC converter station using V / f control mode is equivalent to a synchronous generator, several sets of third data are generated in the transient stability calculation data of the initial data used in the simulation by configuring the values ​​of parameters in the classic generator model, wherein: The synchronous generator kinetic energy EMWS ranges from 50000 to 999999, and the unit of EMWS is MW*second; The per-unit parameter benchmark value of the motor is taken as the local capacity of the synchronous generator or the benchmark capacity of the power system; Direct-axis transient reactance It takes a value between 0.00001 and 0.01 pu.

8. The method according to claim 1, characterized in that, Based on the frequency and damping ratio of the first oscillation mode, and the frequency and damping ratio of the second oscillation mode corresponding to the first oscillation mode, the small disturbance analysis results between the synchronous condenser group and the flexible DC converter station using V / f control mode are determined, including: Calculate the frequency of the second oscillation mode corresponding to the first oscillation mode and the frequency of the first oscillation mode to obtain the frequency deviation; Calculate the damping ratio of the second oscillation mode corresponding to the first oscillation mode and the damping ratio of the first oscillation mode to obtain the damping ratio deviation; When the frequency deviation and the damping ratio deviation meet the set small disturbance analysis validity criteria, the second oscillation mode corresponding to the frequency deviation and the damping ratio deviation is determined, and the frequency and damping ratio of the second oscillation mode are the small disturbance analysis results between the synchronous condenser group and the flexible DC converter station using the V / f control mode. The small disturbance analysis validity criteria are that the frequency deviation is less than the defined frequency deviation threshold and the damping ratio deviation is less than the defined damping ratio deviation threshold.

9. The method according to claim 8, characterized in that, The frequency deviation threshold is set to 0.2 Hz, and the damping ratio deviation threshold is set to 0.1 Hz.

10. A small-disturbance analysis system suitable for high-inertia energy storage synchronous condensers, characterized in that, The system includes: The data acquisition module is used to acquire a set of initial simulation data for the power system where the synchronous condensers are located. The power system includes a new energy power station equipped with synchronous condensers and a complete flexible DC transmission system. The complete flexible DC transmission system includes a flexible DC converter station using V / f control mode. The synchronous condenser group of the new energy power station and the AC bus of the flexible DC converter station using V / f control mode are located in the same synchronous AC network. The initial simulation data satisfies the convergence of power flow calculation and can perform disturbance-free transient stability calculation normally. The initial setup module is used to set the network faults of the power system and the output variables of the synchronous condenser group based on the initial data for simulation. The first analysis module is used to obtain the simulation curve of the output variable after the transient stability calculation containing the network fault is completed, and to determine the first oscillation mode of the synchronous condenser group of the new energy power station in the power system relative to the flexible DC converter station using the V / f control mode, as well as the frequency and damping ratio of the first oscillation mode, based on the simulation curve. The equivalent data module is used to convert the flexible DC converter station using the V / f control mode in the initial data for simulation into a synchronous generator, and generate several sets of equivalent data for simulation. The second analysis module is used to perform small disturbance calculations on at least one set of simulation equivalent data that meet the requirements of power flow calculation convergence and can normally perform disturbance-free transient stability calculations, and to determine the corresponding small disturbance calculation results. The small disturbance results include a second oscillation mode, as well as the oscillation frequency and damping ratio of the second oscillation mode. The result output module is used to determine the small disturbance analysis results between the synchronous condenser group of the new energy power station and the flexible DC converter station using the V / f control mode, based on the frequency and damping ratio of the first oscillation mode and the frequency and damping ratio of the second oscillation mode corresponding to the first oscillation mode.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method as described in any one of claims 1-9.

12. An electronic device, characterized in that, include: processor; Memory used to store the processor's executable instructions; The processor is configured to read the executable instructions from the memory and execute the executable instructions to implement the steps of the method according to any one of claims 1-9.

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