Flexible coal power synchronous generator wideband harmonic impedance modeling method and related equipment

Abstract

The application discloses a flexible coal power synchronous generator wideband harmonic impedance modeling method and related equipment, constructs a small signal model of a synchronous generator unit considering a prime mover speed regulation system and a generator excitation system, obtains an output impedance expression of the synchronous generator through theoretical analysis and mathematical derivation, and provides a model basis and theoretical support for stability research of a hybrid new energy and thermal power unit. Based on analysis of the synchronous generator, a synchronous generator original impedance model is established, considering the influence of the generator excitation regulation system and the prime mover speed regulation system on the output impedance, a synchronous generator impedance model considering only the excitation system and a synchronous generator impedance model considering only the prime mover speed regulation system are established, the impedance analysis results of the generator excitation system and the prime mover speed regulation system are combined, a complete synchronous generator impedance expression containing excitation and speed regulation control is obtained, and the correctness of the impedance modeling result and the effectiveness of the modeling scheme are ensured.

Description

Technical Field

[0001] This invention belongs to the field of impedance modeling technology, specifically a flexible broadband harmonic impedance modeling method and related equipment for coal-fired synchronous generators. Background Technology

[0002] With the continuous advancement of carbon peaking and carbon neutrality, new energy equipment such as wind power, photovoltaics, and energy storage are being widely used, and my country's power system is gradually entering a critical stage of coal-fired power transformation. However, my country currently has a large number of coal-fired power units, and in the short term, the power generation of new energy sources cannot meet the increase in electricity consumption across society. The high demand for electricity from the public means that coal-fired power units still need to provide most of the incremental demand. At the same time, the peak-load capacity of power sources other than coal-fired power is insufficient to support the growth in electricity load, and the remaining electricity gap needs to be filled by traditional coal-fired power. Therefore, before energy storage technology is fully developed, coal-fired power cannot be withdrawn from the electricity market. Wind and solar power are responsible for low-carbon development, while traditional coal-fired power is responsible for peak shaving and regulation. Coal-fired power still plays a significant supporting role in the stable operation of the power system.

[0003] Against the backdrop of accelerating energy structure transformation, the diversity of coupling forms between power electronic equipment such as wind power and photovoltaics, power transmission networks and traditional thermal power has gradually highlighted the problem of broadband electromagnetic oscillation, which seriously affects equipment safety and power quality, restricts the efficient consumption of new energy sources, and threatens the safety and stability of the power grid.

[0004] Impedance stability analysis is a modular, efficient, and accurate stability analysis method widely used in the analysis of broadband electromagnetic oscillations. Impedance analysis requires simplifying each module using the Thevenin or Norton equivalent principle to establish its impedance model. The system impedance ratio is determined based on the relationships between the equivalent impedance models, and then the stability characteristics of the power system are analyzed according to the Nyquist criterion. Since impedance-based stability analysis methods rely on accurate impedance models, establishing impedance models for scenarios involving the coordinated operation of thermal power and new energy sources is crucial.

[0005] From the perspective of power systems, accurately and completely establishing equivalent impedance models for each subsystem is a prerequisite for stability analysis. Currently, some progress has been made in impedance modeling for voltage source converters (VSCs). Researchers have established relatively complete converter impedance models based on different control modes, and have also made significant advancements in subsequent impedance characteristic analysis, instability mechanism research, system stability analysis, and optimization. Impedance models of voltage source converters are widely used in scenarios where new energy power generation equipment is connected to the power system. However, while research on impedance modeling for new energy power systems is deepening, there is relatively little research on impedance modeling for traditional thermal power scenarios. Synchronous generators, as a basic building block of traditional power systems, have impedance modeling as the foundation for the stability analysis of the entire system. Establishing impedance models for synchronous generators is of great significance for the stability analysis of systems under today's complex energy structures. Summary of the Invention

[0006] This invention provides a flexible broadband harmonic impedance modeling method and related equipment for coal-fired synchronous generators to solve the problem of insufficient impedance models for thermal power units in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A flexible method for modeling broadband harmonic impedance of coal-fired synchronous generators includes:

[0009] Establish the original impedance model of the synchronous generator;

[0010] Based on the original impedance model of the synchronous generator, an impedance model of the synchronous generator considering only the excitation system is established.

[0011] Based on the original impedance model of the synchronous generator, an impedance model of the synchronous generator considering only the prime mover speed control system is established.

[0012] Based on the original impedance model of the synchronous generator, the impedance model of the synchronous generator considering only the excitation system, and the impedance model of the synchronous generator considering only the prime mover speed control system, a synchronous generator impedance model that simultaneously includes excitation and speed control is established.

[0013] Preferably, the establishment of the original impedance model of the synchronous generator is specifically as follows:

[0014] Based on the rotor winding voltage balance equation of the synchronous generator, the subtransient electromotive force (EMF) of the d-axis and q-axis in the synchronous rotating coordinate system is determined. Based on the subtransient EMF, stator winding flux linkage equation, and stator winding voltage balance equation, and ignoring the influence of the excitation system, the transfer function between the stator voltage, stator current, and rotor angular velocity of the synchronous generator is obtained. Based on the rotor motion equation, the transfer function between the rotor angular velocity and the net rotor shaft torque is determined. The relationship between mechanical power and mechanical torque is obtained, and ignoring the influence of the speed regulation system, the transfer function between mechanical torque and rotor angular velocity is obtained. Based on the electromagnetic torque expression and the stator winding flux linkage equation, the transfer function between electromagnetic torque and stator current is determined. Based on the obtained transfer functions, the original impedance model of the synchronous generator is established.

[0015] The original impedance model of the synchronous generator is:

[0016]

[0017] Z out_sg Z is the output impedance of the synchronous generator. out G is the impedance matrix between the stator winding voltage and the stator winding current. ωt G is the transfer function between the rotor angular velocity and the net torque of the rotor shaft. mω Let g be the transfer function between mechanical torque and rotor angular velocity. ti This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. Let g be the transfer function between the stator winding flux linkage and the stator winding current. vω This is the transfer function between the stator winding voltage and the rotor angular velocity.

[0018] Preferably, the establishment of the synchronous generator impedance model considering only the excitation system is specifically as follows:

[0019] A mathematical model of the generator excitation system is established. Based on the mathematical model of the excitation system, the transfer function vector between the stator voltage and the magnitude of the stator voltage vector, and the transfer function between the magnitude of the stator voltage vector and the hypothetical no-load potential are obtained. Based on the excitation system transfer function and the original impedance model of the synchronous generator, an impedance model of the synchronous generator considering only the excitation system is established.

[0020] Preferably, considering only the excitation system, the synchronous generator impedance model is as follows:

[0021]

[0022] Z out_exc To consider only the output impedance of the excitation regulation system, I is a 2×2 identity matrix, G excLet g be the transfer function between the magnitude of the stator voltage vector and the hypothetical no-load potential, k1 represent the transfer function vector between the stator voltage and the magnitude of the stator voltage vector, and g be the transfer function between the stator voltage and the magnitude of the stator voltage vector. ve Z represents the transfer function vector between the stator voltage and the hypothetical no-load potential. out G is the impedance matrix between stator voltage and stator current. ωt G is the transfer function between the rotor angular velocity and the net torque of the rotor shaft. mω Let g be the transfer function between mechanical torque and rotor angular velocity. ti This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. Let g be the transfer function between the stator winding flux linkage and the stator winding current. vω This is the transfer function between the stator winding voltage and the rotor angular velocity. This is the transfer function between the stator winding flux linkage and the hypothetical no-load potential.

[0023] Preferably, the establishment of the synchronous generator impedance model considering only the prime mover speed control system is specifically as follows:

[0024] A mathematical model of the prime mover speed regulation system is obtained. Based on the mathematical model of the prime mover speed regulation system, the transfer function between mechanical power and rotor angular velocity can be obtained. Based on the expression of mechanical torque, the transfer function between mechanical torque and rotor angular velocity and the transfer function between mechanical torque and mechanical power are obtained. Finally, based on the transfer function of the synchronous generator and the transfer function of the speed regulation system, the impedance model of the synchronous generator considering only the prime mover speed regulation system is obtained.

[0025] Preferably, considering only the synchronous generator impedance model of the prime mover speed control system, the model is as follows:

[0026]

[0027] Z out_gov To consider only the output impedance of the speed control system, G ωt G1 is the transfer function between rotor angular velocity and rotor shaft net torque, G2 is the transfer function between mechanical torque and rotor angular velocity, and G3 is the transfer function between mechanical torque and mechanical power. gov Let g be the transfer function between mechanical power and rotor angular velocity. ti This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. Let g be the transfer function between the stator winding flux linkage and the stator winding current. vω Z is the transfer function between the stator winding voltage vector and the rotor angular velocity. outThis is the impedance matrix between stator voltage and stator current.

[0028] Preferably, the impedance model of the synchronous generator that simultaneously includes excitation and speed control is as follows:

[0029]

[0030] I is a 2×2 identity matrix, G ωt Let g be the transfer function between the rotor angular velocity and the net rotor shaft torque. vω G is the transfer function between the stator winding voltage vector and the rotor angular velocity. exc Let g be the transfer function between the magnitude of the stator voltage vector and the hypothetical no-load potential. ve Let G1 be the transfer function vector between stator voltage and hypothetical no-load potential, k1 be the transfer function vector between stator voltage and the magnitude of stator voltage vector, G1 be the transfer function between mechanical torque and rotor angular velocity, and G2 be the transfer function between mechanical torque and mechanical power. gov Let g be the transfer function between mechanical power and rotor angular velocity. ti This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. This is the transfer function between the stator winding flux linkage and the stator winding current. Z is the transfer function between the stator winding flux linkage and the hypothetical no-load potential. out This is the impedance matrix between stator voltage and stator current.

[0031] A flexible broadband harmonic impedance modeling system for coal-fired synchronous generators includes:

[0032] First model building module: used to build the original impedance model of the synchronous generator;

[0033] The second model building module is used to build a synchronous generator impedance model that only considers the excitation system, based on the original impedance model of the synchronous generator.

[0034] The third model building module is used to build a synchronous generator impedance model that only considers the prime mover speed control system, based on the original impedance model of the synchronous generator.

[0035] Overall Model Building Module: This module is used to build a synchronous generator impedance model that includes both excitation and speed control, based on the original synchronous generator impedance model, the synchronous generator impedance model considering only the excitation system, and the synchronous generator impedance model considering only the prime mover speed control system.

[0036] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements steps such as a method for modeling broadband harmonic impedance of a flexible coal-fired synchronous generator.

[0037] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of a method for modeling the broadband harmonic impedance of a flexible coal-fired synchronous generator.

[0038] Compared with existing technologies, this invention has the following advantages: This invention provides a flexible broadband harmonic impedance modeling method for coal-fired synchronous generators. Based on synchronous generator analysis, it establishes an impedance model for thermal power units. First, it establishes the original impedance model of the synchronous generator. Then, considering the influence of the excitation regulation system, the prime mover speed control system, and the rotor motion equation on the output impedance, it establishes synchronous generator impedance models considering only the excitation system and only the prime mover speed control system, respectively. This ensures the correctness of the impedance modeling results and the effectiveness of the modeling scheme, helping to further guarantee the stability of the system in scenarios where new energy and thermal power units work together. Compared with existing impedance modeling theories, this method is more targeted and fills the theoretical gap in synchronous generator impedance models. Attached Figure Description

[0039] Figure 1 Flowchart of a method for modeling broadband harmonic impedance of flexible coal-fired synchronous generators;

[0040] Figure 2 Block diagram of a broadband harmonic impedance modeling system for flexible coal-fired synchronous generators;

[0041] Figure 3 This is the original small-signal control block diagram for a synchronous generator;

[0042] Figure 4 This is a small-signal model of a synchronous generator that only considers the excitation system;

[0043] Figure 5 This is a small-signal model of a synchronous generator that only considers the speed control system;

[0044] Figure 6 This is a small-signal model of a synchronous generator that simultaneously considers the excitation system and the speed control system. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0046] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0047] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0048] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0049] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0050] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0051] like Figure 1 The present invention provides a flexible broadband harmonic impedance modeling method for coal-fired synchronous generators, comprising:

[0052] S101 Establish the original impedance model of the synchronous generator;

[0053] S102 establishes a synchronous generator impedance model that only considers the excitation system based on the original impedance model of the synchronous generator.

[0054] S103 establishes a synchronous generator impedance model that only considers the prime mover speed control system based on the original impedance model of the synchronous generator.

[0055] S104 establishes a synchronous generator impedance model that simultaneously includes excitation and speed control based on the original impedance model of the synchronous generator, the synchronous generator impedance model considering only the excitation system, and the synchronous generator impedance model considering only the prime mover speed control system.

[0056] The establishment of the original impedance model of the synchronous generator is specifically as follows:

[0057] Based on the rotor winding voltage balance equation of the synchronous generator, the subtransient electromotive force (EMF) of the d-axis and q-axis in the synchronous rotating coordinate system is determined. Based on the subtransient EMF, stator winding flux linkage, and stator winding voltage balance equation, and ignoring the influence of the excitation system, the transfer function between the stator voltage, stator current, and rotor angular velocity of the synchronous generator is obtained. Based on the rotor motion equation, the transfer function between the rotor angular velocity and the net rotor shaft torque is determined. The relationship between mechanical power and mechanical torque is obtained, and ignoring the influence of the speed regulation system, the transfer function between mechanical torque and rotor angular velocity is obtained. Based on the electromagnetic torque expression and the stator winding flux linkage equation, the transfer function between electromagnetic torque and stator current is determined. Based on the obtained transfer functions, the original impedance model of the synchronous generator is established.

[0058] The original impedance model of the synchronous generator is:

[0059]

[0060] Z out_sg Z is the output impedance of the synchronous generator. out G is the impedance matrix between the stator winding voltage and the stator winding current. ωt G is the transfer function between the rotor angular velocity and the net torque of the rotor shaft. mω Let g be the transfer function between mechanical torque and rotor angular velocity. ti This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. Let g be the transfer function between the stator winding flux linkage and the stator winding current. vω This is the transfer function between the stator winding voltage and the rotor angular velocity.

[0061] The establishment of the synchronous generator impedance model considering only the excitation system is specifically as follows:

[0062] A mathematical model of the generator excitation system is established. Based on the mathematical model of the excitation system, the transfer function vector between the stator voltage and the magnitude of the stator voltage vector and the transfer function between the magnitude of the stator voltage vector and the hypothetical no-load potential are obtained. Based on the excitation system transfer function and the original transfer function of the synchronous generator, an impedance model of the synchronous generator considering only the excitation system is established.

[0063] The impedance model of the synchronous generator considering only the excitation system is as follows:

[0064]

[0065] Z out_exc To consider only the output impedance of the excitation regulation system, I is a 2×2 identity matrix, G exc Let g be the transfer function between the magnitude of the stator voltage vector and the hypothetical no-load potential, k1 represent the transfer function vector between the stator voltage and the magnitude of the stator voltage vector, and g be the transfer function between the stator voltage and the magnitude of the stator voltage vector. ve Z represents the transfer function vector between the stator voltage and the hypothetical no-load potential. out G is the impedance matrix between stator voltage and stator current. ωt G is the transfer function between the rotor angular velocity and the net torque of the rotor shaft. mω Let g be the transfer function between mechanical torque and rotor angular velocity. ti This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. Let g be the transfer function between the stator winding flux linkage and the stator winding current. vω This is the transfer function between the stator winding voltage and the rotor angular velocity. This is the transfer function between the stator winding flux linkage and the hypothetical no-load potential.

[0066] The establishment of the synchronous generator impedance model considering only the prime mover speed control system is as follows:

[0067] A mathematical model of the prime mover speed regulation system is obtained. Based on this model, the transfer functions between mechanical power and rotor angular velocity can be derived. Using the expression for mechanical torque, the transfer functions between mechanical torque and rotor angular velocity, as well as between mechanical torque and mechanical power, are obtained. Finally, based on the original transfer function of the synchronous generator and the transfer function of the speed regulation system, an impedance model of the synchronous generator considering only the prime mover speed regulation system is obtained.

[0068] The synchronous generator impedance model considering only the prime mover speed control system is as follows:

[0069]

[0070] Z out_gov To consider only the output impedance of the speed control system, G ωt G1 is the transfer function between rotor angular velocity and rotor shaft net torque, G2 is the transfer function between mechanical torque and rotor angular velocity, and G3 is the transfer function between mechanical torque and mechanical power. gov Let g be the transfer function between mechanical power and rotor angular velocity. ti This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. Let g be the transfer function between the stator winding flux linkage and the stator winding current. vω Z is the transfer function between the stator winding voltage vector and the rotor angular velocity. out This is the impedance matrix between stator voltage and stator current.

[0071] The impedance model of the synchronous generator that simultaneously includes excitation and speed control is as follows:

[0072]

[0073] I is a 2×2 identity matrix, G ωt Let g be the transfer function between the rotor angular velocity and the net rotor shaft torque. vω G is the transfer function between the stator winding voltage vector and the rotor angular velocity. exc Let g be the transfer function between the magnitude of the stator voltage vector and the hypothetical no-load potential. ve Let G1 be the transfer function vector between stator voltage and hypothetical no-load potential, k1 be the transfer function vector between stator voltage and the magnitude of stator voltage vector, G1 be the transfer function between mechanical torque and rotor angular velocity, and G2 be the transfer function between mechanical torque and mechanical power. gov Let g be the transfer function between mechanical power and rotor angular velocity. ti This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. This is the transfer function between the stator winding flux linkage and the stator winding current. Z is the transfer function between the stator winding flux linkage and the hypothetical no-load potential. out This is the impedance matrix between stator voltage and stator current.

[0074] Example:

[0075] To address the stability analysis problem under the interaction of new energy and thermal power units, a synchronous generator impedance modeling method based on small-signal analysis is proposed. A small-signal control block diagram of the synchronous generator unit based on influencing factors such as the prime mover speed regulation system and the generator excitation system is constructed. The output impedance expression of the synchronous generator is obtained through theoretical analysis and mathematical derivation, providing a model basis and theoretical support for the stability study of hybrid new energy and thermal power units. The specific modeling process is as follows.

[0076] 1. Original Impedance Model of Synchronous Generator

[0077] The original small-signal control block diagram of the synchronous generator is as follows: Figure 3 As shown. Among them, and These represent the small-signal values ​​of the current and voltage components of the stator windings of the synchronous generator in the synchronous rotating coordinate system, specifically the d-axis and q-axis components. Z is the small signal value of the rotor angular velocity controlled by the speed regulation system. out G is the impedance matrix between the stator winding voltage and the stator winding current. ωt G is the transfer function between the rotor angular velocity and the net torque of the rotor shaft. mω Let g be the transfer function between mechanical torque and rotor angular velocity. ti This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. Let g be the transfer function between the stator winding flux linkage and the stator winding current. vω This is the transfer function between the stator winding voltage and the rotor angular velocity. Unless otherwise specified, variables and parameters are per-unit values.

[0078] Assuming the synchronous generator's magnetic circuit is symmetrical and unsaturated, and the spatial magnetomotive force is sinusoidally distributed, then the voltage balance equations for the stator and rotor windings are:

[0079]

[0080]

[0081] The stator winding flux linkage equation can be expressed as:

[0082]

[0083] The algebraic variable e″ can be solved from the rotor winding voltage balance equation (2). d and e″ q For convenience, let

[0084]

[0085] Then e″d and e″ q Represented as

[0086]

[0087] e″ of equation (5) d and e″ q Substituting into the stator winding flux linkage and voltage balance equations, and through mathematical derivation, while eliminating steady-state values ​​and neglecting higher-order infinitesimals, and assuming the influence of the excitation system is ignored, the original small-signal model of the synchronous generator can be obtained, where the impedance matrix Z... out and the transfer function vector g vω The expression is

[0088]

[0089]

[0090] The small-signal voltage value of the stator winding can be expressed as:

[0091]

[0092] The stator winding voltage balance equation of a synchronous generator introduces the rotor angular velocity ω, which is closely related to the rotor motion equation. The rotor motion equation is:

[0093]

[0094] The relationship between mechanical power and mechanical torque can be expressed as follows:

[0095] P m =T m ω (10)

[0096] The expression for electromagnetic torque is:

[0097]

[0098] From the rotor motion equation of equation (9), we can obtain

[0099]

[0100] Assuming the influence of the speed control system is ignored, then P m It can be considered a constant, and from the relationship between mechanical power and mechanical torque in equation (10), we can obtain...

[0101]

[0102] Eliminating steady-state values ​​and ignoring higher-order infinitesimals results in

[0103]

[0104] From the electromagnetic torque expression of equation (11), we can obtain

[0105]

[0106] in

[0107]

[0108] At the same time but

[0109]

[0110] according to Figure 3 The block diagram shown can be used to solve for the output impedance of the synchronous generator.

[0111]

[0112] 2. Synchronous generator impedance model considering only the excitation system

[0113] To generate a magnetic field in the generator stator space and maintain the required generator terminal voltage and corresponding reactive power output, a suitable DC current needs to be supplied to the generator's excitation winding. The voltage balance equation for the synchronous generator rotor winding contains the variable E. fq If we only consider the effect of the excitation system on the synchronous generator, then the effect of the speed control system on the synchronous generator can be ignored, that is... The stator voltage v, stator current i, rotor electrical angular velocity ω, and hypothetical no-load potential E are used. fq Linearization, eliminating steady-state values ​​and ignoring higher-order infinitesimals, yields:

[0114]

[0115] Small-signal model of synchronous generator, such as Figure 4 As shown. Where k1 represents the stator voltage. The magnitude of the stator voltage vector The transfer function vector between them, G exc The magnitude of the stator voltage vector and hypothetical no-load potential The transfer function between them, g ve Z represents the transfer function vector between the stator voltage and the hypothetical no-load potential. out G is the impedance matrix between stator voltage and stator current. ωt G is the transfer function between the rotor angular velocity and the net torque of the rotor shaft. mω Let g be the transfer function between mechanical torque and rotor angular velocity. ti This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. Let g be the transfer function between the stator winding flux linkage and the stator winding current. vω This is the transfer function between the stator winding voltage and the rotor angular velocity. This is the transfer function between the stator winding flux linkage and the hypothetical no-load potential.

[0116] The hypothetical no-load potential can be expressed as

[0117]

[0118] The hypothetical no-load potential E from equation (20) fq The expression yields

[0119]

[0120] By eliminating the steady-state value and ignoring higher-order infinitesimals, we can obtain k1 and G. exc expression

[0121]

[0122]

[0123] The small-signal model of the excitation system can be obtained by refining the model.

[0124]

[0125] From the stator winding flux linkage balance equation, we can know

[0126]

[0127] in

[0128]

[0129] according to Figure 4 The control block diagram shown can be mathematically derived to obtain the output impedance expression considering only the excitation regulation system.

[0130]

[0131] 3. Synchronous generator impedance model considering only the prime mover speed control system

[0132] The stator winding voltage balance equation of a synchronous generator introduces the rotor angular velocity ω, which is closely related to the rotor motion equation. The generator's rotor motion equation contains the variable T. m variable T m With P m Closely related, P mSince the generator is controlled by the speed regulation system, it is necessary to analyze the impact of the prime mover speed regulation system on the generator output impedance.

[0133] The prime mover mechanical power P in the rotor motion equation m It is related to the operating conditions of the prime mover and is controlled by the speed control system. When the role of the speed control system is taken into account, that is, P is not considered... m When the constant value is used, the mathematical model of the prime mover speed regulation system can be obtained as follows:

[0134]

[0135] When only considering the effect of the speed control system on the output impedance, the disturbance of the hypothetical no-load potential The value is 0. Considering the small-signal model of the synchronous generator in the speed regulation system, it is shown in equation (8).

[0136] From the relationship between mechanical power and mechanical torque, we can obtain

[0137]

[0138] Eliminating steady-state values ​​and ignoring higher-order infinitesimals results in

[0139]

[0140] From the mechanical power expression of equation (28), we can obtain

[0141]

[0142] according to Figure 5 The transfer function block diagram shown can be mathematically derived to obtain the expression for the output impedance considering only the speed control system.

[0143]

[0144] 4. Impedance Modeling Method for Synchronous Generator Sets

[0145] The voltage balance equation of the synchronous generator rotor winding contains the variable E. fq Hypothetical no-load potential E fq The synchronous generator is controlled by the generator excitation system. Meanwhile, the voltage balance equation of the stator winding of the synchronous generator introduces the variable ω. The rotor electrical angular velocity ω is affected by mechanical and electromagnetic torque, while the mechanical torque of the prime mover is controlled by the speed regulation system. Therefore, the actual synchronous generator is jointly controlled by the excitation system and the speed regulation system, requiring the establishment of a synchronous generator output impedance model that simultaneously considers both the excitation system and the speed regulation system. Figure 6To develop a small-signal model of a synchronous generator that simultaneously considers both the excitation and speed control systems, through mathematical derivation and block diagram simplification, and combining the impedance analysis results considering only the generator excitation system or the prime mover speed control system, a comprehensive solution yields the complete impedance expression for the synchronous generator that simultaneously includes excitation and speed control.

[0146]

[0147] like Figure 2 As shown, the present invention also provides a flexible broadband harmonic impedance modeling system for coal-fired synchronous generators, comprising:

[0148] First model building module: used to build the original impedance model of the synchronous generator;

[0149] The second model building module is used to build a synchronous generator impedance model that only considers the excitation system.

[0150] The third model building module is used to build a synchronous generator impedance model that only considers the prime mover speed regulation system.

[0151] Overall Model Building Module: This module is used to build a synchronous generator impedance model that includes both excitation and speed control, based on the original synchronous generator impedance model, the synchronous generator impedance model considering only the excitation system, and the synchronous generator impedance model considering only the prime mover speed control system.

[0152] An embodiment of the present invention provides a terminal device. This terminal device includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the various method embodiments described above. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the various device embodiments described above.

[0153] The computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention.

[0154] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0155] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0156] The memory can be used to store the computer program and / or module. The processor implements various functions of the terminal device by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0157] If the modules / units integrated into the terminal device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0158] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art, guided by the specification, can make many other modifications without departing from the scope of the claims of the present invention, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A flexible broadband harmonic impedance modeling method for coal-fired synchronous generators, characterized in that, include: Establish the original impedance model of the synchronous generator; Based on the original impedance model of the synchronous generator, an impedance model of the synchronous generator considering only the excitation system is established. Based on the original impedance model of the synchronous generator, an impedance model of the synchronous generator considering only the prime mover speed control system is established. Based on the original impedance model of the synchronous generator, the impedance model of the synchronous generator considering only the excitation system, and the impedance model of the synchronous generator considering only the prime mover speed control system, a synchronous generator impedance model that simultaneously includes excitation and speed control is established, which is the flexible coal-fired synchronous generator broadband harmonic impedance model. The impedance model of the synchronous generator that simultaneously includes excitation and speed control is as follows: for The identity matrix, This is the transfer function between the rotor angular velocity and the net torque of the rotor shaft. The transfer function between stator winding voltage and rotor angular velocity. Let be the transfer function between the magnitude of the stator voltage vector and the hypothetical no-load potential. The vector representing the transfer function between the stator voltage and the hypothetical no-load potential. The vector representing the transfer function between the stator voltage and the magnitude of the stator voltage vector. The transfer function between mechanical torque and rotor angular velocity. This is the transfer function between mechanical torque and mechanical power. This is the transfer function between mechanical power and rotor angular velocity. This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. This is the transfer function between the stator winding flux linkage and the stator winding current. Let be the transfer function between the stator winding flux linkage and the hypothetical no-load potential. This is the impedance matrix between the stator winding voltage and the stator winding current. The output impedance of a synchronous generator that simultaneously includes excitation and speed control.

2. The method for modeling broadband harmonic impedance of flexible coal-fired synchronous generators according to claim 1, characterized in that, The establishment of the original impedance model of the synchronous generator is specifically as follows: Based on the rotor winding voltage balance equation of the synchronous generator, the subtransient electromotive force (EMF) of the d-axis and q-axis in the synchronous rotating coordinate system is determined. Based on the subtransient EMF, stator winding flux linkage equation, and stator winding voltage balance equation, and ignoring the influence of the excitation system, the transfer function between the stator voltage, stator current, and rotor angular velocity of the synchronous generator is obtained. Based on the rotor motion equation, the transfer function between the rotor angular velocity and the net rotor shaft torque is determined. The relationship between mechanical power and mechanical torque is obtained, and ignoring the influence of the speed regulation system, the transfer function between mechanical torque and rotor angular velocity is obtained. Based on the electromagnetic torque expression and the stator winding flux linkage equation, the transfer function between electromagnetic torque and stator current is determined. Based on the obtained transfer functions, the original impedance model of the synchronous generator is established. The original impedance model of the synchronous generator is: in The output impedance of the synchronous generator. This is the impedance matrix between the stator winding voltage and the stator winding current. This is the transfer function between the rotor angular velocity and the net torque of the rotor shaft. This is the transfer function between mechanical torque and rotor angular velocity when only the excitation system is considered. This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. This is the transfer function between the stator winding flux linkage and the stator winding current. This is the transfer function between the stator winding voltage and the rotor angular velocity.

3. The method for modeling broadband harmonic impedance of flexible coal-fired synchronous generators according to claim 1, characterized in that, The establishment of the synchronous generator impedance model considering only the excitation system is specifically as follows: A mathematical model of the generator excitation system is established. Based on the mathematical model of the excitation system, the transfer function vector between the stator voltage and the magnitude of the stator voltage vector, and the transfer function between the magnitude of the stator voltage vector and the hypothetical no-load potential are obtained. Based on the excitation system transfer function and the original impedance model of the synchronous generator, an impedance model of the synchronous generator considering only the excitation system is established.

4. The method for modeling broadband harmonic impedance of flexible coal-fired synchronous generators according to claim 3, characterized in that, The impedance model of the synchronous generator considering only the excitation system is as follows: in To consider only the output impedance of the excitation regulation system, for The identity matrix, Let be the transfer function between the magnitude of the stator voltage vector and the hypothetical no-load potential. The vector representing the transfer function between the stator voltage and the magnitude of the stator voltage vector. The vector representing the transfer function between the stator voltage and the hypothetical no-load potential. This is the impedance matrix between the stator winding voltage and the stator winding current. This is the transfer function between the rotor angular velocity and the net torque of the rotor shaft. This is the transfer function between mechanical torque and rotor angular velocity when only the excitation system is considered. This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. This is the transfer function between the stator winding flux linkage and the stator winding current. The transfer function between stator winding voltage and rotor angular velocity. This is the transfer function between the stator winding flux linkage and the hypothetical no-load potential.

5. The method for modeling broadband harmonic impedance of flexible coal-fired synchronous generators according to claim 1, characterized in that, The establishment of the synchronous generator impedance model considering only the prime mover speed control system is as follows: A mathematical model of the prime mover speed regulation system is obtained. Based on the mathematical model of the prime mover speed regulation system, the transfer function between mechanical power and rotor angular velocity can be obtained. Based on the expression of mechanical torque, the transfer function between mechanical torque and rotor angular velocity and the transfer function between mechanical torque and mechanical power are obtained. Finally, based on the transfer function of the synchronous generator and the transfer function of the speed regulation system, the impedance model of the synchronous generator considering only the prime mover speed regulation system is obtained.

6. The method for modeling broadband harmonic impedance of flexible coal-fired synchronous generators according to claim 5, characterized in that, The synchronous generator impedance model considering only the prime mover speed control system is as follows: in To consider only the output impedance of the speed control system, This is the transfer function between the rotor angular velocity and the net torque of the rotor shaft. The transfer function between mechanical torque and rotor angular velocity. This is the transfer function between mechanical torque and mechanical power. This is the transfer function between mechanical power and rotor angular velocity. This is the transfer function between electromagnetic torque and stator winding current. This is the transfer function between electromagnetic torque and stator winding flux linkage. This is the transfer function between the stator winding flux linkage and the stator winding current. The transfer function between stator winding voltage and rotor angular velocity. This is the impedance matrix between the stator winding voltage and the stator winding current.

7. A flexible broadband harmonic impedance modeling system for coal-fired synchronous generators, characterized in that, The method for implementing the broadband harmonic impedance modeling method for flexible coal-fired synchronous generators according to any one of claims 1-6 includes: First model building module: used to build the original impedance model of the synchronous generator; The second model building module is used to build a synchronous generator impedance model that only considers the excitation system, based on the original impedance model of the synchronous generator. The third model building module is used to build a synchronous generator impedance model that only considers the prime mover speed control system, based on the original impedance model of the synchronous generator. Overall Model Building Module: This module is used to build a synchronous generator impedance model that includes both excitation and speed control, based on the original synchronous generator impedance model, the synchronous generator impedance model considering only the excitation system, and the synchronous generator impedance model considering only the prime mover speed control system.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the flexible coal-fired synchronous generator broadband harmonic impedance modeling method as described in any one of claims 1 to 6.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the broadband harmonic impedance modeling method for flexible coal-fired synchronous generators as described in any one of claims 1 to 6.

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