Oscillation stability analysis method and system suitable for photo-thermal photovoltaic coupling power generation system

Abstract

The invention discloses an oscillation stability analysis method and system suitable for a photo-thermal photovoltaic coupling power generation system. The method comprises the following steps: establishing a small signal model of a photo-thermal photovoltaic coupling power generation system network according to an equivalent circuit; establishing a small signal model of each subsystem in the photovoltaic power generation system to obtain a phase-locked loop-based small signal model of the photovoltaic power generation system; and establishing a small signal model of the photo-thermal generator set based on the internal electrical relationship of the photo-thermal generator set and the electrical relationship between the PCC nodes. Establishing an integral small-signal model of the photo-thermal photovoltaic coupling power generation system, and calculating a characteristic value, a left characteristic vector, a right characteristic vector and a participation factor of the photo-thermal photovoltaic coupling power generation system; and according to the characteristic values, the left and right characteristic vectors and the participation factors, analyzing the oscillation stability of the photo-thermal photovoltaic coupling power generation system. According to the method, the dynamic state of the photo-thermal photovoltaic coupling power generation system can be well reflected, the oscillation stability of the photo-thermal photovoltaic coupling power generation system can be effectively analyzed, the modeling process is simple and clear, and the method can be popularized to stability analysis of other systems.

Description

Technical Field

[0001] The present invention relates to the field of power system modeling, and in particular to an oscillation stability analysis method and system applicable to a solar-thermal-photovoltaic coupled power generation system. Background Art

[0002] Among all types of renewable energy power generation, solar thermal power generation has the ability to provide continuous power supply day and night, while providing the inertial support and backup energy required for the stability of the power grid. Solar thermal power generation has a relatively small impact on the environment, and its heat storage medium (such as molten salt) can be recycled. At the same time, with the continuous advancement of power electronic equipment and grid-connected control technology, photovoltaic power generation technology has gradually matured, and its installed capacity has continued to increase. Nevertheless, solar thermal power generation and photovoltaic power generation are limited by weather conditions, which makes them more suitable for large-scale development in areas with sufficient sunshine (such as deserts and wastelands).

[0003] To more efficiently utilize solar energy resources in the same region, CSP plants and photovoltaic bases are typically connected to the same or nearby grid connection points, forming a CSP-PV coupled power generation system. Unlike traditional synchronous units, CSP generators have smaller individual capacities and are more numerous. Improper excitation controller parameter settings can lead to electromagnetic oscillations within the CSP plant. Furthermore, the use of large-scale power electronic converters in grid-connected photovoltaic systems can introduce negative damping characteristics into the entire coupled power generation system, further destabilizing the grid and exacerbating electromagnetic oscillations.

[0004] Currently, research on oscillation stability primarily focuses on photovoltaic power generation systems connected to the grid via inverters. Existing research uses the system's dynamic processes and control strategies to achieve dynamic modeling of photovoltaic power generation systems, thereby conducting oscillation stability analysis. However, this research has certain limitations. First, in actual production applications, to efficiently utilize solar energy resources in the same region, an increasing number of CSP and PV power generation systems are connected to the grid at the same or nearby grid connection points. Existing research, which focuses solely on the oscillation stability of photovoltaic power generation systems, ignores the impact of CSP units on the entire power generation system, resulting in certain limitations. Second, existing technologies lack in-depth research on overall dynamic modeling, small signal modeling, and oscillation stability analysis of CSP-PV coupled power generation systems. Summary of the Invention

[0005] The object of the present invention is to provide an oscillation stability analysis method and system applicable to a solar-thermal-photovoltaic coupled power generation system to solve the above-mentioned problems.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides an oscillation stability analysis method applicable to a solar-thermal-photovoltaic coupled power generation system, comprising:

[0008] Construct the corresponding equivalent circuit model according to the coupled power generation system network topology, and establish the small signal model of the solar-thermal-photovoltaic coupled power generation system network based on the equivalent circuit;

[0009] Establish the small signal model of each subsystem in the photovoltaic power generation system and obtain the small signal model of the photovoltaic power generation system based on the phase-locked loop;

[0010] A small signal model of each subsystem of the CSP generator set is established, and a small signal model of the CSP generator set is established based on the internal electrical relationship of the CSP generator set and the electrical relationship between PCC nodes.

[0011] Combining the small signal model of the photovoltaic power generation system, the small signal model of the solar thermal power generation unit and the small signal model of the solar thermal photovoltaic coupled power generation system network, an overall small signal model of the solar thermal photovoltaic coupled power generation system is established. The overall small signal model of the solar thermal photovoltaic coupled power generation system is expressed in state space form, and the eigenvalues, left and right eigenvectors and participation factors of the solar thermal photovoltaic coupled power generation system are calculated; based on the eigenvalues, left and right eigenvectors and participation factors, the oscillation stability analysis of the solar thermal photovoltaic coupled power generation system is carried out.

[0012] Furthermore, the corresponding equivalent circuit model is constructed according to the coupled power generation system network topology, and the small signal model of the solar-thermal-photovoltaic coupled power generation system network is established according to the equivalent circuit, including:

[0013] An equivalent circuit model of the solar-thermal-photovoltaic coupled power generation system network is established. The solar-thermal-photovoltaic coupled power generation system network is a Y-type circuit. Each power generation node is coupled to the grid node through the PCC node. According to the circuit equivalent transformation principle, the Y-type circuit is equivalently transformed into a Δ-type circuit. Based on the circuit principle and the equivalent circuit, the small signal model of the coupled power generation system network is derived.

[0014] Furthermore, the small signal model of each subsystem in the photovoltaic power generation system is established to obtain a small signal model of the photovoltaic power generation system based on a phase-locked loop, including:

[0015] Build a small signal model of the DC line:

[0016]

[0017] Where U dc is the DC line voltage, P in1 is the grid-side converter input power, C is the DC line capacitance;

[0018] The grid-side converter adopts voltage and current dual closed-loop control, while ignoring the dynamics of the current inner loop. Based on the basic circuit principles, the voltage and current relationship between the photovoltaic power generation system node and the PCC is derived, and the small signal model of the photovoltaic power generation system grid-side converter is obtained:

[0019]

[0020] Δδ PCC =K4Δδ1+K5ΔP1

[0021] Where, is the introduced intermediate variable, I d is the d-axis current, K P1 and K I1 is the PI controller parameter of the DC voltage control loop, δ PCC is the PCC node phase angle; the superscript “p” represents the corresponding variable in the controller dq coordinate system.

[0022] Furthermore, the small signal model of each subsystem of the CSP generator set is established based on the internal electrical relationship of the CSP generator set and the electrical relationship between PCC nodes, including:

[0023] Construct a small signal model of the excitation subsystem of the CSP generator: generator excitation voltage E fd It consists of two parts: one is the excitation voltage E fd0 , constant; second, the output voltage of the automatic voltage regulator At the same time, the small signal model of the excitation subsystem is established by combining the dynamic model of the automatic voltage regulator and the excitation winding voltage equation.

[0024] Construct a small signal model of the synchronous generator subsystem of the CSP generator set: Based on the synchronous generator rotor motion equation, a small signal model of the synchronous generator subsystem is established;

[0025] Construct a small-signal model for the grid-connected CSP generator set: Based on the internal electrical relationship of the CSP generator set and the electrical relationship between the CSP generator set and the PCC node, a small-signal model for the grid-connected CSP generator set is established.

[0026] Furthermore, the small signal model of the photovoltaic power generation system, the small signal model of the solar thermal power generation unit and the small signal model of the solar thermal photovoltaic coupled power generation system network are combined to establish an overall small signal model of the solar thermal photovoltaic coupled power generation system, including:

[0027] The established solar-thermal-photovoltaic coupled power generation system network small signal model, photovoltaic power generation system small signal model, and solar-thermal generator set small signal model are combined to form an overall small signal model. Through the solar-thermal-photovoltaic coupled power generation system network small signal model, the photovoltaic power generation system and solar-thermal generator set variables are linked. The photovoltaic power generation system small signal model is coupled with the solar-thermal generator set small signal model to realize the construction of the overall small signal model.

[0028] The established small-signal model of the solar-thermal-photovoltaic coupled power generation system network, the small-signal model of the photovoltaic power generation system, and the small-signal model of the solar-thermal power generation unit are Laplace transformed and expressed as a frequency domain transfer function. The overall small-signal model of the solar-thermal-photovoltaic coupled power generation system is displayed through a transfer function block diagram.

[0029] Furthermore, the overall small signal model of the CSP coupled power generation system is expressed in a state space form, and the eigenvalues, left and right eigenvectors, and participation factors of the CSP coupled power generation system are calculated; and based on the eigenvalues, left and right eigenvectors, and participation factors, an oscillation stability analysis of the CSP coupled power generation system is performed, including:

[0030] The overall small signal model of the CSP system is expressed in state space form. Based on the state space form of the overall small signal model of the CSP system, the eigenvalues, left and right eigenvectors, and participation factors of the system are calculated. The specific calculation method is as follows:

[0031] det(A-λI)=0

[0032] (A-λ k I)Φ k =0

[0033] Ψ k (A-λ k I)=0

[0034] Ψ k Φ k =1

[0035] p lk =Φ lk Ψ kl

[0036] Where λ is the eigenvalue of the state matrix A, I is the identity matrix, Φ k is the kth eigenvalue λ k The corresponding right eigenvector, Ψ k is the kth eigenvalue λ k The corresponding left eigenvector, p lk is the participation factor;

[0037] Based on the calculation results of eigenvalues, left and right eigenvectors, and participation factors, a modal analysis of the oscillation stability of the CSP system is performed, as follows:

[0038] The eigenvalues ​​of the state matrix A correspond to the oscillation modes of the system. Specifically, according to the kth eigenvalue λ of the state matrix A k =σ k +jω k , calculate the oscillation frequency f of the kth oscillation mode of the system k and damping ζ k :

[0039]

[0040] The mode shape is given by the right eigenvector Φ k Given, describes the relative activity of the state variables when a specific mode is excited, the participation factor Ψ k It is an indicator to measure the relative participation of the lth state variable in the kth mode.

[0041] In a second aspect, the present invention provides an oscillation stability analysis system applicable to a solar-thermal-photovoltaic coupled power generation system, comprising:

[0042] The first model building module is used to build a corresponding equivalent circuit model according to the coupled power generation system network topology, and to establish a small signal model of the solar-thermal-photovoltaic coupled power generation system network according to the equivalent circuit;

[0043] The second model building module is used to establish a small signal model of each subsystem in the photovoltaic power generation system, and obtain a small signal model of the photovoltaic power generation system based on a phase-locked loop;

[0044] The third model building module is used to establish the small signal model of each subsystem of the CSP generator set, and to establish the small signal model of the CSP generator set based on the internal electrical relationship of the CSP generator set and the electrical relationship between PCC nodes.

[0045] The analysis module is used to combine the small signal model of the photovoltaic power generation system, the small signal model of the solar thermal power generation unit and the small signal model of the solar thermal photovoltaic coupled power generation system network to establish an overall small signal model of the solar thermal photovoltaic coupled power generation system, express the overall small signal model of the solar thermal photovoltaic coupled power generation system in a state space form, calculate the eigenvalues, left and right eigenvectors and participation factors of the solar thermal photovoltaic coupled power generation system; and perform oscillation stability analysis of the solar thermal photovoltaic coupled power generation system based on the eigenvalues, left and right eigenvectors and participation factors.

[0046] Furthermore, the overall small signal model of the CSP system in the analysis module is expressed in a state space form. Based on the state space form of the overall small signal model of the CSP system, the eigenvalues, left and right eigenvectors, and participation factors of the system are calculated. The specific calculation method is as follows:

[0047] det(A-λI)=0

[0048] (A-λ k I)Φ k =0

[0049] Ψ k (A-λ k I)=0

[0050] Ψ k Φ k =1

[0051] p lk =Φ lk Ψ kl

[0052] Where λ is the eigenvalue of the state matrix A, I is the identity matrix, Φ k is the kth eigenvalue λ k The corresponding right eigenvector, Ψ k is the kth eigenvalue λ k The corresponding left eigenvector, p lk is the participation factor;

[0053] Based on the calculation results of eigenvalues, left and right eigenvectors, and participation factors, a modal analysis of the oscillation stability of the CSP system is performed, as follows:

[0054] The eigenvalues ​​of the state matrix A correspond to the oscillation modes of the system. Specifically, according to the kth eigenvalue λ of the state matrix A k =σ k +jω k , calculate the oscillation frequency f of the kth oscillation mode of the system k and damping ζ k :

[0055]

[0056] The mode shape is given by the right eigenvector Φ k Given, describes the relative activity of the state variables when a specific mode is excited, the participation factor Ψ k It is an indicator to measure the relative participation of the lth state variable in the kth mode.

[0057] In a third aspect, the present invention provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the oscillation stability analysis method applicable to a solar-thermal photovoltaic coupled power generation system are implemented.

[0058] In a fourth aspect, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the oscillation stability analysis method applicable to a solar-thermal photovoltaic coupled power generation system.

[0059] Compared with the prior art, the present invention has the following technical effects:

[0060] Based on the consideration of the oscillation stability analysis of the photovoltaic power generation system, the present invention takes into account the influence of the solar thermal power generation unit at the same grid connection point near the photovoltaic power generation, thereby better performing the oscillation stability analysis of the solar thermal photovoltaic coupled power generation system. Specifically, dynamic small signal models of the photovoltaic power generation system and the solar thermal power generation system are established respectively. The photovoltaic power generation system takes into account the dynamics of the DC line, the grid-side converter, etc., while the solar thermal power generation unit takes into account the dynamics of the excitation system and the dynamics of the synchronous generator system, etc. At the same time, coupling is achieved through the network model of the coupled system, thereby better reflecting the dynamics of the solar thermal photovoltaic coupled power generation system. Subsequently, based on the established small signal model of the state space of the entire system, the modal analysis method is used to achieve an effective analysis of the oscillation stability of the solar thermal photovoltaic coupled power generation system. The modeling process is simple and clear, the analysis method is logically clear, and it can be extended to the stability analysis of other systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is a network equivalent circuit diagram of a solar-thermal-photovoltaic coupled power generation system provided by the present invention.

[0062] Figure 2 This is an internal electrical relationship diagram of a photovoltaic power generation system based on a phase-locked loop provided by the present invention.

[0063] Figure 3 This is a transfer function block diagram of a solar-thermal-photovoltaic coupled power generation system provided by the present invention.

[0064] Figure 4 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0065] The present invention will be further described below with reference to the accompanying drawings:

[0066] Example 1, please refer to Figure 4 The present invention provides an oscillation stability analysis method applicable to a solar-thermal-photovoltaic coupled power generation system, comprising:

[0067] Construct the corresponding equivalent circuit model according to the coupled power generation system network topology, and establish the small signal model of the solar-thermal-photovoltaic coupled power generation system network based on the equivalent circuit;

[0068] Establish the small signal model of each subsystem in the photovoltaic power generation system and obtain the small signal model of the photovoltaic power generation system based on the phase-locked loop;

[0069] A small signal model of each subsystem of the CSP generator set is established, and a small signal model of the CSP generator set is established based on the internal electrical relationship of the CSP generator set and the electrical relationship between PCC nodes.

[0070] Combining the small signal model of the photovoltaic power generation system, the small signal model of the solar thermal power generation unit and the small signal model of the solar thermal photovoltaic coupled power generation system network, an overall small signal model of the solar thermal photovoltaic coupled power generation system is established. The overall small signal model of the solar thermal photovoltaic coupled power generation system is expressed in state space form, and the eigenvalues, left and right eigenvectors and participation factors of the solar thermal photovoltaic coupled power generation system are calculated; based on the eigenvalues, left and right eigenvectors and participation factors, the oscillation stability analysis of the solar thermal photovoltaic coupled power generation system is carried out.

[0071] The present invention can better reflect the dynamics of the solar-thermal-photovoltaic coupled power generation system and effectively analyze the oscillation stability of the solar-thermal-photovoltaic coupled power generation system. The modeling process is simple and clear and can be extended to the stability analysis of other systems.

[0072] In Example 2, the present invention provides an oscillation stability analysis method applicable to a solar-thermal-photovoltaic coupled power generation system, specifically comprising:

[0073] First, a small-signal model is constructed for the CSP coupled photovoltaic power generation system network. Next, small-signal modeling is performed for the PV system's DC link, grid-side converter subsystem, and phase-locked loop (PLL) grid connection. Next, small-signal modeling is performed for the CSP generator's excitation subsystem and synchronous generator subsystem. Combining these small-signal models, an overall small-signal model of the CSP coupled photovoltaic power generation system is derived. Finally, a modal analysis method for oscillation stability is developed based on the state-space representation of the overall small-signal model of the CSP coupled photovoltaic power generation system.

[0074] Step S1: The CSP-PV coupled system includes CSP generator nodes and PV generation nodes, which are integrated into an equivalent grid node at the PCC. The equivalent grid is modeled as an ideal voltage source. First, an equivalent circuit model is constructed based on the coupled power generation system network topology. Then, a small-signal model of the CSP-PV coupled power generation system network is established based on the equivalent circuit and basic circuit principles.

[0075] The specific steps of step S1 are as follows:

[0076] Step S11: The solar-thermal-photovoltaic coupled power generation system network can be regarded as a Y-type circuit, where each power generation node is coupled to the grid node through the PCC node. According to the circuit equivalent transformation principle, the Y-type circuit can be equivalently transformed into a Δ-type circuit, as shown in Figure 1 As shown, the line equivalent impedance expression is as follows:

[0077]

[0078] Where X12, X1g, and X2g are the equivalent line impedances after transformation, and the subscripts "1," "2," and "g" represent the PV system node, CSP generator node, and grid node, respectively. X1, X2, and Xg are the impedances between the PV system node, CSP generator node, grid node, and PCC node, respectively.

[0079] Step S12: Establish a small signal model of the solar-thermal-photovoltaic coupled power generation system network. Based on the circuit principle and equivalent circuit, the small signal model of the coupled power generation system network is derived:

[0080] ΔP1=K1Δδ1+K2Δδ2

[0081] ΔP2=K2Δδ1+K3Δδ2

[0082] Where P1 and δ1 are the active power and phase angle of the photovoltaic power generation system node output respectively, and P2 and δ2 are the active power and phase angle of the solar thermal power generation unit node output respectively. U1, U2, U g are the node voltages of photovoltaic, solar thermal, and power grid, respectively. Δ is a small perturbation of the corresponding variable. The subscript “0” represents the value of the corresponding variable at the steady-state operating point of the system. These two notations will be used in the following sections.

[0083] Step S2: The photovoltaic power generation system includes a DC line and a grid-side converter subsystem. First, a small signal model of each subsystem in the photovoltaic power generation system is established; then, a phase-locked loop-based photovoltaic power generation grid-connected small signal model is established.

[0084] The specific steps of step S2 are as follows:

[0085] Step S21: Ignore the resistance of the DC line between the generator-side converter and the grid-side converter, only consider the filter capacitor on the line, and ignore the active power loss of the converter to establish a small signal model of the DC line:

[0086]

[0087] Where U dc is the DC line voltage, P in1 is the grid-side converter input power, and C is the DC line capacitance.

[0088] Step S22: First, dual closed-loop voltage and current control is applied to the grid-side converter, while ignoring the inner current loop dynamics. Then, based on the basic circuit principles, the voltage and current relationship between the photovoltaic power generation system node 1 and the PCC is derived, i.e., the small signal model of the photovoltaic power generation system grid-side converter is:

[0089]

[0090] Δδ PCC =K4Δδ1+K5ΔP1

[0091] Where, is the introduced intermediate variable, I d is the d-axis current, K P1 and K I1 is the PI controller parameter of the DC voltage control loop, δ PCC is the PCC node phase angle. The superscript “p” denotes the corresponding variable in the controller dq coordinate system, and this notation will be used in the following.

[0092] Step S23: The photovoltaic power generation system uses phase-locked loop technology to track the PCC node voltage phase angle. Its internal electrical relationship is as follows: Figure 2 As shown in the figure, according to the internal electrical relationship and the dynamic process of the phase-locked loop controller, a small signal model of the photovoltaic power generation system grid-connected based on the phase-locked loop is established:

[0093]

[0094] Where θ PLL is the phase-locked loop phase angle, and is the introduced intermediate variable, K P2 and K I2 are the PI controller parameters of the phase-locked loop control loop.

[0095] Step S3: The CSP generator set includes an excitation subsystem and a synchronous generator subsystem. First, a small-signal model of each subsystem of the CSP generator set is established. Then, based on the electrical relationships within the CSP generator set and the electrical relationships between PCC nodes, a small-signal model of CSP grid connection is established.

[0096] The specific steps of step S3 are as follows:

[0097] Step S31: The generator excitation voltage Efd consists of two parts: one is the excitation voltage Efd0, which is constant; the other is the output voltage of the automatic voltage regulator At the same time, combining the dynamic model of the automatic voltage regulator and the excitation winding voltage equation, a small signal model of the excitation subsystem is established:

[0098] ΔE fd =ΔEfd0 +ΔE′ fd

[0099]

[0100] Where KA is the gain of the automatic voltage regulator, TA is the time constant of the automatic voltage regulator, is the quadrature axis transient electromotive force of the CSP generator set, E q is the quadrature axis no-load electromotive force.

[0101] Step S32: Based on the synchronous generator rotor motion equation, a small signal model of the synchronous generator subsystem is established:

[0102]

[0103] Where M is the rotor inertia constant; P in2 is the input mechanical power; D is the damping coefficient; ω0 is the synchronous speed; ω2 is the speed of the synchronous generator of the solar thermal unit.

[0104] Step S33: Based on the internal electrical relationship of the CSP generator set and the electrical relationship between the CSP generator set and the PCC node, a small signal model for the CSP generator set to be connected to the grid is established:

[0105]

[0106] Where,

[0107]

[0108] X′ dΣ =X2+X′ d , X qΣ =X2+X q , X dΣ =X2+X d , X′ d is the d-axis transient reactance, X d 、X q are the self-reactances of the d and q axes, U 2d 、U 2q are the d and q components of the node voltage of the CSP generator set, respectively.

[0109] Step S4: comprehensively considering the small signal model of the photovoltaic power generation system, the small signal model of the solar thermal power generation unit and the small signal model of the solar thermal photovoltaic coupled power generation system network, an overall small signal model of the solar thermal photovoltaic coupled power generation system is established.

[0110] The specific steps of step S4 are as follows:

[0111] Step S41: Comprehensively consider the small signal models of the photovoltaic power generation system, the solar thermal power generation unit and the solar thermal photovoltaic coupled power generation system network to obtain the overall small signal model of the solar thermal photovoltaic coupled power generation system.

[0112] Step S42: The overall small signal model of the solar-thermal-photovoltaic coupled power generation system is expressed in the form of a transfer function block diagram, as shown in Figure 3 .

[0113] Step S5: First, the overall small signal model of the solar-thermal-photovoltaic coupled power generation system is expressed in state space form; then, the eigenvalues, left and right eigenvectors, and participation factors of the solar-thermal-photovoltaic coupled power generation system are calculated; finally, based on the eigenvalues, left and right eigenvectors, and participation factors, a modal analysis method for the oscillation stability of the solar-thermal-photovoltaic coupled power generation system is established.

[0114] The specific steps of step S5 are as follows:

[0115] Step S51: Express the overall small signal model of the solar-thermal-photovoltaic coupled power generation system in step S41 in a state space form:

[0116]

[0117] Where x is the system state variable and A is the system state matrix.

[0118] Step S52: Based on the state space form of the overall small signal model of the CSP system, the eigenvalue, left and right eigenvectors, and participation factor of the system are calculated. The specific calculation method is as follows:

[0119] det(A-λI)=0

[0120] (A-λ k I)Φ k =0

[0121] Ψ k (A-λ k I)=0

[0122] Ψ k Φ k =1

[0123] p lk =Φ lk Ψ kl

[0124] Where λ is the eigenvalue of the state matrix A, I is the identity matrix, Φ k is the kth eigenvalue λ k The corresponding right eigenvector, Ψ k is the kth eigenvalue λ k The corresponding left eigenvector, p lkis the participation factor.

[0125] Step S53: Based on the calculation results of the eigenvalues, left and right eigenvectors, and participation factors, a modal analysis method for the oscillation stability of the solar-thermal-photovoltaic coupled power generation system is established, as follows.

[0126] The eigenvalues ​​of the state matrix A correspond to the oscillation modes of the system. Specifically, according to the kth eigenvalue λ of the state matrix A k =σ k +jω k , the oscillation frequency f of the kth oscillation mode of the system can be calculated k and damping ζ k :

[0127]

[0128] The mode shape is given by the right eigenvector Φ k Given, it describes the relative activity of the state variables when a specific mode is excited. If the vector Φ k If the magnitude of the lth element of is significant, then the kth mode of the corresponding eigenvalue is one of the main modes affecting the lth state variable of the system. k It is an indicator to measure the relative participation of the lth state variable in the kth mode.

[0129] In yet another embodiment of the present invention, an oscillation stability analysis system applicable to a solar-thermal-photovoltaic coupled power generation system is provided, which can be used to implement the above-mentioned oscillation stability analysis method applicable to a solar-thermal-photovoltaic coupled power generation system. Specifically, the system includes:

[0130] The first model building module is used to build a corresponding equivalent circuit model according to the coupled power generation system network topology, and to establish a small signal model of the solar-thermal-photovoltaic coupled power generation system network according to the equivalent circuit;

[0131] The second model building module is used to establish a small signal model of each subsystem in the photovoltaic power generation system, and obtain a small signal model of the photovoltaic power generation system based on a phase-locked loop;

[0132] The third model building module is used to establish the small signal model of each subsystem of the CSP generator set, and to establish the small signal model of the CSP generator set based on the internal electrical relationship of the CSP generator set and the electrical relationship between PCC nodes.

[0133] The analysis module is used to combine the small signal model of the photovoltaic power generation system, the small signal model of the solar thermal power generation unit and the small signal model of the solar thermal photovoltaic coupled power generation system network to establish an overall small signal model of the solar thermal photovoltaic coupled power generation system, express the overall small signal model of the solar thermal photovoltaic coupled power generation system in a state space form, calculate the eigenvalues, left and right eigenvectors and participation factors of the solar thermal photovoltaic coupled power generation system; and perform oscillation stability analysis of the solar thermal photovoltaic coupled power generation system based on the eigenvalues, left and right eigenvectors and participation factors.

[0134] The module division in the embodiments of the present invention is illustrative and represents only one logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional modules in various embodiments of the present invention may be integrated into a single processor, exist physically as separate modules, or two or more modules may be integrated into a single module. The integrated modules may be implemented in either hardware or software functional modules.

[0135] In another embodiment of the present invention, a computer device is provided, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function; the processor described in the embodiment of the present invention can be used for the operation of the oscillation stability analysis method applicable to the solar thermal photovoltaic coupled power generation system.

[0136] In another embodiment of the present invention, the present invention further provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It is understandable that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the oscillation stability analysis method applicable to the solar-thermal photovoltaic coupled power generation system in the above embodiment.

[0137] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0138] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0139] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0140] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. An oscillation stability analysis method applicable to a solar-thermal-photovoltaic coupled power generation system, characterized in that: include: Construct the corresponding equivalent circuit model according to the coupled power generation system network topology, and establish the small signal model of the solar-thermal-photovoltaic coupled power generation system network based on the equivalent circuit; Establish the small signal model of each subsystem in the photovoltaic power generation system and obtain the small signal model of the photovoltaic power generation system based on the phase-locked loop; Establish a small signal model for each subsystem of the CSP generator set. This model is based on the electrical relationships within the CSP generator set and between PCC nodes. Combining the small signal model of the photovoltaic power generation system, the small signal model of the solar thermal power generation unit and the small signal model of the solar thermal photovoltaic coupled power generation system network, an overall small signal model of the solar thermal photovoltaic coupled power generation system is established. The overall small signal model of the solar thermal photovoltaic coupled power generation system is expressed in state space form, and the eigenvalues, left and right eigenvectors and participation factors of the solar thermal photovoltaic coupled power generation system are calculated; based on the eigenvalues, left and right eigenvectors and participation factors, the oscillation stability analysis of the solar thermal photovoltaic coupled power generation system is carried out.

2. The oscillation stability analysis method for a solar-thermal-photovoltaic coupled power generation system according to claim 1, characterized in that: The method of constructing a corresponding equivalent circuit model according to the coupled power generation system network topology and establishing a small signal model of the solar-thermal-photovoltaic coupled power generation system network according to the equivalent circuit includes: An equivalent circuit model of the solar-thermal-photovoltaic coupled power generation system network is established. The solar-thermal-photovoltaic coupled power generation system network is a Y-type circuit. Each power generation node is coupled to the grid node through the PCC node. According to the circuit equivalent transformation principle, the Y-type circuit is equivalently transformed into a Δ-type circuit. Based on the circuit principle and the equivalent circuit, the small signal model of the coupled power generation system network is derived.

3. The oscillation stability analysis method for a solar-thermal-photovoltaic coupled power generation system according to claim 1, characterized in that: The small signal model of each subsystem in the photovoltaic power generation system is established to obtain a small signal model of the photovoltaic power generation system based on a phase-locked loop, including: Build a small signal model of the DC line: Where U dc is the DC line voltage, P in1 is the grid-side converter input power, C is the DC line capacitance; The grid-side converter adopts voltage and current dual closed-loop control, while ignoring the dynamics of the current inner loop. Based on the basic circuit principles, the voltage and current relationship between the photovoltaic power generation system node and the PCC is derived, and the small signal model of the photovoltaic power generation system grid-side converter is obtained: Where, is the introduced intermediate variable, I d is the d-axis current, K P1 and K I1 is the PI controller parameter of the DC voltage control loop, δ PCC is the PCC node phase angle; the superscript "p" represents the corresponding variable in the controller dq coordinate system.

4. The oscillation stability analysis method for a solar-thermal-photovoltaic coupled power generation system according to claim 1, characterized in that: The small signal model of each subsystem of the CSP generator set is established based on the internal electrical relationship of the CSP generator set and the electrical relationship between PCC nodes, including: Construct a small signal model of the excitation subsystem of the CSP generator: generator excitation voltage E fd It consists of two parts: one is the excitation voltage E fd0 , constant; second, the output voltage of the automatic voltage regulator At the same time, the small signal model of the excitation subsystem is established by combining the dynamic model of the automatic voltage regulator and the excitation winding voltage equation. Construct a small signal model of the synchronous generator subsystem of the CSP generator set: Based on the synchronous generator rotor motion equation, a small signal model of the synchronous generator subsystem is established; Construct a small-signal model for the grid-connected CSP generator set: Based on the internal electrical relationship of the CSP generator set and the electrical relationship between the CSP generator set and the PCC node, a small-signal model for the grid-connected CSP generator set is established.

5. The oscillation stability analysis method applicable to a solar-thermal-photovoltaic coupled power generation system according to claim 1, characterized in that: The small signal model of the photovoltaic power generation system, the small signal model of the solar thermal power generation unit and the small signal model of the solar thermal photovoltaic coupled power generation system network are combined to establish an overall small signal model of the solar thermal photovoltaic coupled power generation system, including: The established solar-thermal-photovoltaic coupled power generation system network small signal model, photovoltaic power generation system small signal model, and solar-thermal generator set small signal model are combined to form an overall small signal model. Through the solar-thermal-photovoltaic coupled power generation system network small signal model, the photovoltaic power generation system and solar-thermal generator set variables are linked. The photovoltaic power generation system small signal model is coupled with the solar-thermal generator set small signal model to realize the construction of the overall small signal model. The established small-signal model of the solar-thermal-photovoltaic coupled power generation system network, the small-signal model of the photovoltaic power generation system, and the small-signal model of the solar-thermal power generation unit are Laplace transformed and expressed as a frequency domain transfer function. The overall small-signal model of the solar-thermal-photovoltaic coupled power generation system is displayed through a transfer function block diagram.

6. The oscillation stability analysis method for a solar-thermal-photovoltaic coupled power generation system according to claim 1, characterized in that: The overall small signal model of the CSP coupled power generation system is expressed in a state space form, and the eigenvalues, left and right eigenvectors, and participation factors of the CSP coupled power generation system are calculated; and the oscillation stability analysis of the CSP coupled power generation system is performed based on the eigenvalues, left and right eigenvectors, and participation factors, including: The overall small signal model of the CSP system is expressed in state space form. Based on the state space form of the overall small signal model of the CSP system, the eigenvalues, left and right eigenvectors, and participation factors of the system are calculated. The specific calculation method is as follows: det(A-λI)=0 (A-λ k I)F k =0 P k (A-λ k I)=0 P k F k =1 p lk =Φ lk P kl Where λ is the eigenvalue of the state matrix A, I is the identity matrix, Φ k is the kth eigenvalue λ k The corresponding right eigenvector, Ψ k is the kth eigenvalue λ k The corresponding left eigenvector, p lk is the participation factor; Based on the calculation results of eigenvalues, left and right eigenvectors, and participation factors, a modal analysis of the oscillation stability of the CSP system is performed, as follows: The eigenvalues ​​of the state matrix A correspond to the oscillation modes of the system. Specifically, according to the kth eigenvalue λ of the state matrix A k =σ k +jω k , calculate the oscillation frequency f of the kth oscillation mode of the system k and damping ζ k : The mode shape is given by the right eigenvector Φ k Given, describes the relative activity of the state variables when a specific mode is excited, the participation factor Ψ k It is an indicator to measure the relative participation of the lth state variable in the kth mode.

7. An oscillation stability analysis system suitable for a solar-thermal-photovoltaic coupled power generation system, characterized in that: include: The first model building module is used to build a corresponding equivalent circuit model according to the coupled power generation system network topology, and to establish a small signal model of the solar-thermal-photovoltaic coupled power generation system network according to the equivalent circuit; The second model building module is used to establish a small signal model of each subsystem in the photovoltaic power generation system, and obtain a small signal model of the photovoltaic power generation system based on a phase-locked loop; The third model building module is used to establish the small signal model of each subsystem of the CSP generator set. The small signal model of the CSP generator set is established based on the internal electrical relationship of the CSP generator set and the electrical relationship between PCC nodes. The analysis module is used to combine the small signal model of the photovoltaic power generation system, the small signal model of the solar thermal power generation unit and the small signal model of the solar thermal photovoltaic coupled power generation system network to establish an overall small signal model of the solar thermal photovoltaic coupled power generation system, express the overall small signal model of the solar thermal photovoltaic coupled power generation system in a state space form, calculate the eigenvalues, left and right eigenvectors and participation factors of the solar thermal photovoltaic coupled power generation system; and perform oscillation stability analysis of the solar thermal photovoltaic coupled power generation system based on the eigenvalues, left and right eigenvectors and participation factors.

8. The oscillation stability analysis system for a solar-thermal-photovoltaic coupled power generation system according to claim 7, characterized in that: In the analysis module, the overall small signal model of the CSP system is expressed in state space form. Based on the state space form of the overall small signal model of the CSP system, the eigenvalues, left and right eigenvectors, and participation factors of the system are calculated. The specific calculation method is as follows: det(A-λI)=0 (A-λ k I)F k =0 P k (A-λ k I)=0 P k F k =1 p lk =Φ lk P kl Where λ is the eigenvalue of the state matrix A, I is the identity matrix, Φ k is the kth eigenvalue λ k The corresponding right eigenvector, Ψ k is the kth eigenvalue λ k The corresponding left eigenvector, p lk is the participation factor; Based on the calculation results of eigenvalues, left and right eigenvectors, and participation factors, a modal analysis of the oscillation stability of the CSP system is performed, as follows: The eigenvalues ​​of the state matrix A correspond to the oscillation modes of the system. Specifically, according to the kth eigenvalue λ of the state matrix A k =σ k +jω k , calculate the oscillation frequency f of the kth oscillation mode of the system k and damping ζ k : The mode shape is given by the right eigenvector Φ k Given, describes the relative activity of the state variables when a specific mode is excited, the participation factor Ψ k It is an indicator to measure the relative participation of the lth state variable in the kth mode.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the oscillation stability analysis method applicable to a solar-thermal-photovoltaic coupled power generation system as claimed in any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the oscillation stability analysis method applicable to a solar-thermal-photovoltaic coupled power generation system as claimed in any one of claims 1 to 6 are implemented.

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