Electric power system electromagnetic oscillation stabilizer and stabilization method

Abstract

The invention belongs to the technical field of power system stability control, and particularly discloses a power system electromagnetic oscillation stabilizer and a stabilization method. The stabilizer comprises an input conversion system, a state conversion system and a state feedback control system, the input conversion system is used for determining a target control position where the external power system has a target electromagnetic oscillation mode so as to obtain an original electromagnetic oscillation signal of the external power system at the target control position; the state conversion system is used for outputting a target signal related to a characteristic value of the external power system based on the original electromagnetic oscillation signal generated at the target control position; the state feedback control system is used for measuring a target signal and generating a control signal through a state feedback control law based on an observer by using the target signal, so that a real part of a characteristic value of the external power system is a negative number. According to the invention, the power system can reach a high stability margin, the electromagnetic oscillation of the power system is effectively suppressed, and a safety guarantee is provided for the operation of a large-scale power grid.

Description

Technical Field

[0001] The present application belongs to the technical field of power system stability control, and more specifically, relates to a power system electromagnetic oscillation stabilizer and a stabilization method. Background Art

[0002] In the development history of the smart grid industry, with the large-scale application of power electronic equipment represented by wind power, photovoltaics, and DC transmission, modern power systems have shown power electronic characteristics. Power electronic equipment generally has a complex multi-scale cascade control structure, complex dynamic characteristics, and is prone to induce electromagnetic oscillation problems. In recent years, electromagnetic oscillation problems in power systems at home and abroad have occurred frequently, with frequencies ranging from a few hertz to several thousand hertz, causing damage to power equipment, disconnection of new energy sites, and shutdown of DC transmission systems, and even affecting the safe and stable operation of large-scale power grids, causing significant economic losses. Designing a stable control strategy to effectively suppress electromagnetic oscillations is of great significance to ensure the safe and stable operation of power systems. Due to the widespread existence of phase-locked loops, switch switching and other links, power electronic equipment such as wind power, photovoltaics, and DC transmission have time-varying characteristics. Specifically, their steady-state operation trajectories contain multiple frequency components. Existing studies have shown that the above time-varying characteristics have an important influence on the electromagnetic oscillation mode of the power system. Therefore, in order to effectively suppress electromagnetic oscillations and ensure the safe operation of large-scale power grids, the time-varying characteristics of power electronic equipment need to be considered when designing stable control strategies.

[0003] The electromagnetic oscillation stabilization control strategy of the existing power system mainly includes subsynchronous oscillation damper based on linear time-invariant state space theory and virtual impedance control based on impedance theory. However, in the above electromagnetic oscillation stabilization control strategy, the derivation of the relevant control law is based on time-invariant processing, and in this process, some time-varying characteristics of the system are ignored. Therefore, the linear time-invariant model as the basis for the derivation of the control law is not accurate enough, which leads to the limited stability margin that the power system can achieve in actual application, and it is difficult to apply to power systems containing large-scale power electronic equipment.

[0004] Therefore, how to better achieve stable control of electromagnetic oscillations in power systems has become a technical problem that needs to be urgently solved in the industry. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of this application is to better achieve stable control of electromagnetic oscillations in power systems, aiming to solve the problem that in the actual application of existing electromagnetic oscillation stability control strategies, the stability margin that can be achieved by power systems is limited and it is difficult to apply to power systems containing large-scale power electronic equipment.

[0006] To achieve the above objectives, in a first aspect, the present application provides an electromagnetic oscillation stabilizer for an electric power system, comprising: Input transformation system, state conversion system and state feedback control system; The output end of the input transformation system is connected to the input end of the external power system; the input end of the state conversion system is connected to the output end of the external power system, and the output end of the state conversion system is connected to the input end of the state feedback control system; the input end of the input transformation system is connected to the output end of the state feedback control system; The input transformation system is used to determine the target control position where the target electromagnetic oscillation mode exists in the external power system, so as to obtain the original electromagnetic oscillation signal of the external power system at the target control position; The state conversion system is used to output a target signal related to the eigenvalue of the external power system based on the original electromagnetic oscillation signal generated at the target control position; The state feedback control system is used to measure the target signal, and use the target signal to generate a control signal through the state feedback control law based on the observer, so that the real part of the eigenvalue of the external power system is negative. Optionally, the state conversion system includes an oscillation signal output system, a filter and an output transformation system connected in sequence; the input of the oscillation signal output system is used as the input end of the state conversion system, and the output end of the output transformation system is used as the output end of the state conversion system; The oscillation signal output system is used to obtain the original electromagnetic oscillation signal generated by the external power system at the target control position; The filter is used to filter the original electromagnetic oscillation signal to obtain the electromagnetic oscillation signal in the target frequency band; The output transformation system is used to perform signal conversion on the electromagnetic oscillation signal in the target frequency band and output a target signal related to the eigenvalue of the external power system.

[0007] In a second aspect, the present application provides a stabilization method applied to the power system electromagnetic oscillation stabilizer described in any one of the foregoing, including: The input transformation system determines the target control position where the target electromagnetic oscillation mode exists in the external power system, so as to obtain the original electromagnetic oscillation signal of the external power system at the target control position; The state conversion system outputs a target signal related to the eigenvalue of the external power system based on the original electromagnetic oscillation signal generated at the target control position; The state feedback control system measures the target signal, and uses the target signal to generate a control signal through the state feedback control law based on the observer, so that the real part of the eigenvalue of the target power system is negative. Optionally, the state transition system includes an oscillation signal output system, a filter, and an output transformation system that are connected in sequence; Correspondingly, the state transition system outputs a target signal related to the eigenvalue of the external power system based on the original electromagnetic oscillation signal generated at the target control position, including: The oscillation signal output system acquires the original electromagnetic oscillation signal generated by the external power system at the target control position; The filter filters the original electromagnetic oscillation signal to obtain an electromagnetic oscillation signal in a target frequency band; The output transformation system performs signal conversion on the electromagnetic oscillation signal in the target frequency band and outputs a target signal related to the eigenvalue of the external power system.

[0008] Optionally, before the input transformation system determines the target control position of the target electromagnetic oscillation mode in the external power system, the method further includes: Converting the linear periodic time-varying model of the external power system into a first linear model with the eigenvalue matrix of the external power system as the system matrix; Sorting the elements in the system eigenvalue matrix in descending order according to the real part of the eigenvalue, and dividing the sorted eigenvalue matrix into a first eigenvalue matrix and a second eigenvalue matrix; Performing block input-output transformation on the first linear model using the first eigenvalue matrix and the second eigenvalue matrix to obtain a second linear model; the second linear model includes a block input matrix and a block output matrix; Based on the controllability and observability analysis results of the first eigenvalue matrix, simplifying the second linear model into a third linear model with the target control position as a variable.

[0009] Optionally, the converting the linear periodic time-varying model of the external power system into a first linear model with the eigenvalue matrix of the external power system as the system matrix includes: Solving the state transition matrix of the linear periodic time-varying model of the external power system to determine the eigenvalue matrix of the state transition matrix, so as to obtain the eigenvalue matrix of the external power system; Determining a periodic time-varying transformation matrix based on the system eigenvalue matrix; Using the periodic time-varying transformation matrix to convert the linear periodic time-varying model into a first linear model with the system eigenvalue matrix as the system matrix.

[0010] Optionally, before the input transformation system determines the target control position of the target electromagnetic oscillation mode in the external power system, the method further includes: Determine the system model of the input transformation system based on the block input matrix of the second linear model and the first eigenvalue matrix.

[0011] Optionally, before the input transformation system determines the target control position of the target electromagnetic oscillation mode in the external power system, the method further includes: Determine the system model of the output transformation system based on the first eigenvalue matrix, the block output matrix of the second linear model, and the output variables.

[0012] Optionally, before the input transformation system determines the target control position of the target electromagnetic oscillation mode in the external power system, the method further includes: Obtain the system matrix, input matrix, and output matrix corresponding to the state space model of the filter; Based on the system matrix, the input matrix, the output matrix, the first eigenvalue matrix, the block input matrix, and the block output matrix of the second linear model, construct the system model of a discrete linear time-invariant system; Based on the discrete linear time-invariant system, determine the system model of the state feedback control system based on the observer.

[0013] Optionally, the obtaining the system matrix, input matrix, and output matrix corresponding to the state space model of the filter includes: Obtain the system model of a preset band-pass filter; Using the minimum realization method of the band-pass filter, solve the system model of the band-pass filter to obtain the system matrix, input matrix, and output matrix corresponding to the state space model of the filter.

[0014] Generally speaking, compared with the prior art by the above technical solution conceived by the present application, the following beneficial effects are achieved: An electromagnetic oscillation stabilizer and a stabilization method for a power system provided by the present application, in the scenario of a periodic time-varying power system containing a large number of power electronic devices, form an electromagnetic oscillation stabilizer by designing an input transformation system, a state conversion system, and a state feedback control system. Using state feedback control based on an observer, the control problem of the original continuous linear periodic time-varying power system is transformed into the control problem of a discrete linear time-invariant system, and the eigenvalues of the converted discrete system are configured to the desired positions, so that the real parts of the system eigenvalues are all less than zero and far from the imaginary axis, so that the power system can reach a higher stability margin, and thus can effectively suppress the electromagnetic oscillation of the power system and provide safety guarantee for the operation of a large-scale power grid. Description of the Drawings

[0015] Figure 1 is one of the structural schematic diagrams of the electromagnetic oscillation stabilizer for a power system provided by an embodiment of the present application; Figure 2 This is the second schematic structural diagram of the power system electromagnetic oscillation stabilizer provided by the embodiments of the present application; Figure 3 This is the schematic flow diagram of the power system electromagnetic oscillation stabilization method provided by the embodiments of the present application; Figure 4 This is the schematic design flow diagram of the power system electromagnetic oscillation stabilizer provided by the embodiments of the present application; Figure 5 This is the schematic diagram of the effect of the power system electromagnetic oscillation stabilizer provided by the embodiments of the present application. Detailed implementation manners

[0016] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0017] The terms "first" and "second" in the description and claims of the present application are used to distinguish different objects, rather than to describe a specific order of the objects. For example, the first eigenvalue matrix and the second eigenvalue matrix are used to distinguish different eigenvalue matrices, rather than to describe the specific order of the eigenvalue matrices.

[0018] In the embodiments of the present application, words such as "exemplary" or "for example" are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific manner.

[0019] The embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

[0020] Figure 1 This is one of the schematic structural diagrams of the power system electromagnetic oscillation stabilizer provided by the embodiments of the present application. As Figure 1 shown, it includes: an input transformation system 1, a state conversion system 2, and a state feedback control system 3; The output end of the input transformation system 1 is connected to the input end of the external power system 4; the input end of the state conversion system 2 is connected to the output end of the external power system 4, the output end of the state conversion system 2 is connected to the input end of the state feedback control system 3; the input end of the input transformation system 1 is connected to the output end of the state feedback control system 3; The input transformation system 1 is used to determine the target control location where the target electromagnetic oscillation mode exists in the external power system 4, so as to obtain the original electromagnetic oscillation signal of the external power system 4 at the target control location; The state conversion system 2 is used to output a target signal related to the eigenvalue of the external power system 4 based on the original electromagnetic oscillation signal generated at the target control location of the external power system 4; The state feedback control system 3 is used to measure the target signal and use the target signal to generate a control signal through the observer-based state feedback control law, so that the real part of the eigenvalue of the external power system 4 is negative.

[0021] Specifically, in the embodiment of the present application, a power system electromagnetic oscillation stabilizer is constructed by using three systems: an input transformation system, a state conversion system, and a state feedback control system.

[0022] It should be noted that in the embodiment of the present application, the external power system refers to a power system containing large-scale power electronic devices. Based on the trajectory linearization control theory, a linear periodic time-varying model of the power system containing large-scale power electronic devices can be obtained: ; Where, x ( t ) is the n -dimensional state variable; represents x ( t ) differentiated with respect to time, u ( t ) is the p -dimensional input variable, that is, the undetermined control position information; y ( t ) is the q -dimensional output variable, that is, the measurement signal; A ( t ), B ( t ) and C ( t ) are respectively the n × n -dimensional system matrix, n × p -dimensional input matrix and q × n -dimensional output matrix of the linear periodic time-varying system, and all satisfy: A ( t ) = A ( t + T ), B ( t ) = B ( t + T ), C (t ) = C ( t + T ), where T is the minimum period of the system; A ( t ), B ( t ) and C ( t ) reflect the structure and parameters of the power system with large-scale power electronic devices.

[0023] In the embodiments of the present application, the external power system is connected between the input conversion system and the state conversion system. The state feedback control system feeds back the output of the state conversion system to the input conversion system through feedback control, so that the input conversion system traverses different pending control position information in the external power system until the target control position with the target electromagnetic oscillation mode is determined. Here, the target electromagnetic oscillation mode refers to the electromagnetic oscillation mode with a large electromagnetic oscillation amplitude and weak damping, which is used to determine the target control position in the external power system where significant electromagnetic oscillation occurs.

[0024] Among them, in this process, it can be realized through the following system model of the input conversion system: ; where ξ i is the new input variable, which is a constant in the time interval iT , ( i + 1) T ; i is the result of t / T after rounding; exp(·) is the exponential function; J e1 represents the eigenvalue matrix of the external power system, and its corresponding eigenvalue λ pd is the eigenvalue whose position needs to be reconfigured; u 1( t ) represents the control position with a high controllability for the eigenvalue λ pd of the external power system; represents the block input matrix, which can be determined by performing a periodic time-varying transformation on the input variables of the linear periodic time-varying model.

[0025] Furthermore, the external power system, as the controlled object, provides the original electromagnetic oscillation measurement signal at the target control position.

[0026] In an embodiment of the present application, the state conversion system is mainly responsible for signal processing and system eigenvalue transformation of the original electromagnetic oscillation signal generated at the target control position of the external power system, and outputs a target signal related to the eigenvalues of the external power system. This process can be represented by the following system model: ; Wherein, represents a block output matrix, which can be determined by performing a periodic time-varying transformation on the output variables of the linear periodic time-varying model; represents the eigenvalues of the external power system λ pd measurement signals with relatively high observability.

[0027] Furthermore, in an embodiment of the present application, the state feedback control system can measure the target signal and use the target signal to generate a control signal through an observer-based state feedback control law, so as to control the real part of the eigenvalues of the external power system to remain negative, thereby improving the stability margin of the power system. Continuing to refer to Figure 1 , in an embodiment of the present application, converting the control problem of the original continuous linear periodic time-varying power system into the control problem of a discrete linear time-invariant system can be achieved through the aforementioned linear periodic time-varying model for controllability and observability transformation into a discrete linear time-invariant system. Based on the transformed discrete linear time-invariant system, a corresponding observer-based state feedback control system can be designed, and its model can be represented as: ; Wherein, is the observer state; K is n × n dimensional state feedback matrix, which can make ln( – K ) / T the corresponding target system eigenvalues be the desired eigenvalues λ , and their real parts are all less than 0 and far from the imaginary axis; L is n × n dimensional observer matrix, which can make the absolute value of the real part of the eigenvalues of ln( – L ) / T be 3 to 10 times the absolute value of the real part of the desired eigenvalue λ ; , , respectively represent intermediate variables, which can be determined by Je1 and calculated from the foregoing block input matrix, block output matrix, etc.

[0028] In the embodiments of the present application, after introducing the stabilizer, the eigenvalues of the power system change from λ pd to the desired eigenvalues λ and ln( A e – LC e ) / T The real parts of the above matrix eigenvalues are all less than 0 and far from the imaginary axis. Therefore, after introducing the stabilizer, the power system can have a high stability margin, thereby effectively suppressing the electromagnetic oscillation of the power system.

[0029] The power system electromagnetic oscillation stabilizer of the embodiments of the present application, in the scenario of a periodic time-varying power system containing a large number of power electronic devices, forms an electromagnetic oscillation stabilizer by designing an input transformation system, a state conversion system, and a state feedback control system. Using the state feedback control based on an observer, the control problem of the original continuous linear periodic time-varying power system is transformed into the control problem of a discrete linear time-invariant system, and the eigenvalues of the converted discrete system are configured to the desired positions, so that the real parts of the system eigenvalues are all less than zero and far from the imaginary axis, so that the power system can reach a high stability margin, and further can effectively suppress the electromagnetic oscillation of the power system, providing a safety guarantee for the operation of a large-scale power grid.

[0030] Figure 2 is the second structural schematic diagram of the power system electromagnetic oscillation stabilizer provided by the embodiments of the present application. As Figure 2 shown, in the embodiments of the present application, the state conversion system 2 includes an oscillation signal output system 21, a filter 22, and an output transformation system 23 that are connected in sequence; the input of the oscillation signal output system 21 is used as the input end of the state conversion system 2, and the output end of the output transformation system 23 is used as the output end of the state conversion system 2; The oscillation signal output system 21 is used to obtain the original electromagnetic oscillation signal generated by the external power system at the target control position; The filter 22 is used to filter the original electromagnetic oscillation signal to obtain the electromagnetic oscillation signal in the target frequency band; The output transformation system 23 is used to perform signal conversion on the electromagnetic oscillation signal in the target frequency band and output a target signal related to the eigenvalues of the external power system.

[0031] Specifically, in the embodiments of the present application, the state conversion system includes an oscillation signal output system, a filter, and an output transformation system that are connected in sequence.

[0032] In an embodiment of the present application, the oscillation signal output system can acquire the original electromagnetic oscillation signal generated by the external power system at the target control position. Further, in an embodiment of the present application, a band-pass filter can be used as the filter, which can filter the original electromagnetic oscillation signal to remove the components of other oscillation modes except the concerned oscillation mode, and acquire the electromagnetic oscillation signal in the target frequency band.

[0033] Further, in an embodiment of the present application, the output transformation system can perform signal conversion on the electromagnetic oscillation signal in the target frequency band by utilizing the output characteristics of the above system model, so as to output a target signal related to the eigenvalue of the external power system. .

[0034] The stabilizer in the embodiment of the present application constructs a state transformation system by using an oscillation signal output system, a filter, and an output transformation system connected in sequence, performs filtering and denoising processing on the original electromagnetic oscillation measurement signal of the system, combines the functions of input transformation and output transformation, further simplifies the design process of subsequent state feedback control based on an observer, and is beneficial to improving the electromagnetic oscillation suppression effect of the entire stabilizer.

[0035] Figure 3 is a schematic flow chart of the method for stabilizing electromagnetic oscillations in a power system provided by an embodiment of the present application, which can be applied to any of the aforementioned power system electromagnetic oscillation stabilizers, such as Figure 3 shown, the method includes: Step S100, the input transformation system determines the target control position of the target electromagnetic oscillation mode in the external power system to acquire the original electromagnetic oscillation signal of the external power system at the target control position; Step S200, the state transformation system outputs a target signal related to the eigenvalue of the external power system based on the original electromagnetic oscillation signal generated at the target control position; Step S300, the state feedback control system measures the target signal and uses the target signal to generate a control signal through the state feedback control law based on an observer, so that the real part of the eigenvalue of the external power system is negative. It should be understood that the method in the above embodiment is applied to the aforementioned power system electromagnetic oscillation stabilizer, and its implementation principle and technical effect are similar to the description of the above stabilizer. The detailed process of this method can refer to the corresponding description process in the stabilizer embodiment above, and will not be elaborated here.

[0036] The electromagnetic oscillation stability method of the embodiment of the present application, in the scenario of a periodic time-varying power system with a large number of power electronic devices, forms an electromagnetic oscillation stabilizer by designing an input transformation system, a state conversion system, and a state feedback control system. Using observer-based state feedback control, the control problem of the original continuous linear periodic time-varying power system is transformed into the control problem of a discrete linear time-invariant system. The eigenvalues of the transformed discrete system are configured to the desired positions, so that the real parts of the system eigenvalues are all less than zero and far away from the imaginary axis, so that the power system can reach a higher stability margin, and thus can effectively suppress the electromagnetic oscillation of the power system and improve the safety guarantee of the operation of the large-scale power grid.

[0037] Based on the content of the above embodiment, as an alternative embodiment, the state conversion system includes an oscillation signal output system, a filter, and an output transformation system connected in sequence; Correspondingly, the state conversion system outputs a target signal related to the eigenvalues of the external power system based on the original electromagnetic oscillation signal generated at the target control position of the external power system, including: The oscillation signal output system obtains the original electromagnetic oscillation signal generated by the external power system at the target control position; The filter filters the original electromagnetic oscillation signal to obtain the electromagnetic oscillation signal in the target frequency band; The output transformation system performs signal conversion on the electromagnetic oscillation signal in the target frequency band and outputs a target signal related to the eigenvalues of the external power system.

[0038] The method of the embodiment of the present application constructs a state conversion system by using an oscillation signal output system, a filter, and an output transformation system connected in sequence, performs filtering and denoising processing on the original electromagnetic oscillation measurement signal of the system, combines the functions of input transformation and output transformation, further simplifies the design process of the subsequent observer-based state feedback control, and is beneficial to improving the electromagnetic oscillation suppression effect of the entire stabilizer.

[0039] Based on the content of the above embodiment, as an alternative embodiment, before the input transformation system determines the target control position of the target electromagnetic oscillation mode of the external power system, the method further includes: Converting the linear periodic time-varying model of the external power system into a first linear model with the eigenvalue matrix of the external power system as the system matrix; Sorting the elements in the system eigenvalue matrix in descending order according to the real part of the eigenvalue, and dividing the sorted eigenvalue matrix into a first eigenvalue matrix and a second eigenvalue matrix; Performing block input-output transformation on the first linear model by using the first eigenvalue matrix and the second eigenvalue matrix to obtain a second linear model; the second linear model includes a block input matrix and a block output matrix; Based on the controllability and observability analysis results of the first eigenvalue matrix, the second linear model is simplified to a third linear model with the target control position as the variable.

[0040] Specifically, in the embodiments of the present application, before putting the power system electromagnetic oscillation stabilizer into application, it is also necessary to design and calculate each system of the stabilizer.

[0041] In the embodiments of the present application, first, according to the linear periodic time-varying model of the external power system introduced above, through eigenvalue matrix calculation, the linear periodic time-varying model of the external power system is converted into a first linear model with the eigenvalue matrix of the external power system as the system matrix.

[0042] Based on the content of the above embodiments, as an alternative embodiment, converting the linear periodic time-varying model of the external power system into a first linear model with the eigenvalue matrix of the external power system as the system matrix includes: Solving the state transition matrix of the linear periodic time-varying model of the external power system to determine the eigenvalue matrix of the state transition matrix, so as to obtain the eigenvalue matrix of the external power system; Based on the system eigenvalue matrix, determining the periodic time-varying transformation matrix; Using the periodic time-varying transformation matrix to convert the linear periodic time-varying model into a first linear model with the system eigenvalue matrix as the system matrix.

[0043] In the embodiments of the present application, using the numerical calculation method, according to the linear periodic time-varying model of the power system, solve the value of the state transition matrix Φ( t , 0) in the time interval [0, T , and then solve the eigenvalues and eigenvectors of the state transition matrix Φ( T , 0) at the moment T . This process can be expressed as: ; Wherein, Q is the diagonal matrix composed of the eigenvalues of Φ( T , 0), and U (0), V (0) are the left and right eigenvectors respectively.

[0044] Furthermore, calculate the eigenvalue matrix J of the power system: ; Wherein, J is a diagonal matrix, and its diagonal elements are the eigenvalues of the linear periodic time-varying system, reflecting the stability of the power system.

[0045] Furthermore, takingU (0) is the initial value. By solving the following preset differential equation, the periodic time-varying transformation matrix within the time interval [0, T is obtained. U ( t ) ; Furthermore, by using the formula V ( t ) = U -1 ( t ), the periodic time-varying transformation matrix V ( t ) is solved.

[0046] Then, through the transformation formula x ( t ) = U ( t ) z ( t ), the linear periodic time-varying model of the aforementioned power system is transformed into a first linear model with the system eigenvalue matrix as the system matrix, which can be expressed as: ; where z ( t ) is the state variable of the transformed system, ( t ) = V ( t ) B ( t ), ( t ) = C ( t ) U ( t ) are respectively the n × p -dimensional input matrix and q × n -dimensional output matrix of the transformed system.

[0047] Furthermore, for the above system eigenvalue matrix J , its elements are sorted in descending order according to the real part to obtain the sorted eigenvalue matrix, which forms a new diagonal matrix J e . Then, this diagonal matrix J e is partitioned into a combination of a first eigenvalue matrix J e1 and a second eigenvalue matrix J e2 , that is: ; Among them, J e1 The real parts of the diagonal elements are all greater than – a , a which is a relatively small positive number; J e2 The real parts of the diagonal elements are all less than or equal to – a . Here, J e1 The corresponding eigenvalue λ pd is the eigenvalue that needs to be reconfigured.

[0048] Furthermore, based on the first eigenvalue matrix J e1 perform controllability and observability analysis, that is, use the following formula to calculate the controllability of the k th input with respect to the J e1 th eigenvalue in i : ; Among them, represents the element in the ( t ) at the i th row and k th column, and |·| represents the modulus of a complex number.

[0049] And calculate the observability of the j th output with respect to the J e1 th eigenvalue in i through the following formula: ; Among them, represents the element in the ( t ) at the j th row and i th column.

[0050] Thus, the controllability of different inputs of the transformed system with respect to the eigenvalue J e1 corresponding to λ pd and the observability of different outputs with respect to λ pd can be calculated. Furthermore, through sorting by magnitude, filter the control positions λ pd with relatively high controllability u 1( t ) and the measurement signals y 1(t )。

[0051] Furthermore, in the embodiments of the present application, the above first linear model is subjected to a block input-output transformation using the first eigenvalue matrix and the second eigenvalue matrix, and the system equation of the transformed linear model is reorganized into the following form to obtain a second linear model, that is: ; wherein, z ( t ) = z 1( t ), z 2( t )] T , u ( t ) = u 1( t ), u 2( t )] T , y ( t ) = y 1( t ), y 2( t )] T 。

[0052] In the formula, z 1( t ) and z 2( t ) are the transformed state variables corresponding to J e1 、 J e2 respectively; 、 、 、 are the block input matrices divided according to the input variables; 、 、 、 are the block output matrices divided according to the output variables.

[0053] Furthermore, in the embodiments of the present application, based on the controllability and observability analysis results of the foregoing first eigenvalue matrix J e1 , the second linear model is simplified to a third linear model with the target control position u 1( t ) as the variable. Specifically, by setting the input variable u 2( t ) to 0 and ignoring the output variable y2( t ), the foregoing transformed system can be further simplified to obtain a third linear model, which can be expressed as: ; Here, according to the above third linear model, the oscillation signal output system can measure y 1( t ) signal, and at the same time, it can provide a reference for the parameter design of the subsequent input transformation system and output transformation system.

[0054] Based on the content of the foregoing embodiments, as an alternative embodiment, before the input transformation system determines the target control position of the target electromagnetic oscillation mode in the external power system, the method further includes: Determining the system model of the input transformation system based on the block input matrix and the first eigenvalue matrix of the second linear model.

[0055] Specifically, in the embodiments of the present application, by combining the foregoing second linear model and third linear model, using the block input matrix and the first eigenvalue matrix J e1 , the following input transformation system can be designed, and its system model can be expressed as: ; Among them, ξ i is a new input variable, and it is a constant in the time interval iT , ( i +1) T ; i is the result of t / T rounded down; exp(·) is an exponential function.

[0056] Based on the content of the foregoing embodiments, as an alternative embodiment, before the input transformation system determines the target control position of the target electromagnetic oscillation mode in the external power system, the method further includes: Determining the system model of the output transformation system based on the first eigenvalue matrix, the block output matrix of the second linear model, and the output variable.

[0057] Specifically, in the embodiments of the present application, by combining the foregoing first eigenvalue matrix J e1 and the block output matrix of the second linear model, and the output variable , the following output transformation system can be designed, and its system model can be expressed as: ; Among them,η i is a new output variable, in the time interval iT , ( i +1) T is a constant.

[0058] Based on the content of the above embodiments, as an alternative embodiment, before the input transformation system determines the target control position of the target electromagnetic oscillation mode in the external power system, the method further includes: Obtain the system matrix, input matrix, and output matrix corresponding to the state space model of the filter; Based on the system matrix, input matrix, output matrix, the first eigenvalue matrix, and the block input matrix and block output matrix of the second linear model, construct the system model of the discrete linear time-invariant system; Based on the discrete linear time-invariant system, determine the system model of the state feedback control system based on the observer.

[0059] Specifically, in the embodiments of the present application, the filter may adopt a band-pass filter, and then obtain the system matrix, input matrix, and output matrix corresponding to the state space model of the band-pass filter.

[0060] Based on the content of the above embodiments, as an alternative embodiment, obtaining the system matrix, input matrix, and output matrix corresponding to the state space model of the filter includes: Obtain the system model of the preset band-pass filter; Use the minimum realization method of the band-pass filter to solve the system model of the band-pass filter, and obtain the system matrix, input matrix, and output matrix corresponding to the state space model of the filter.

[0061] Specifically, in the embodiments of the present application, the system model of the preset band-pass filter may be expressed as follows: ; where ω n represents the center frequency, and the oscillation frequency corresponding to the oscillation mode in the output variable y 1( t ) can be taken; λ pd corresponds to the oscillation frequency of the oscillation mode; k represents the bandwidth ratio, and generally takes a relatively small value such as 0.1.

[0062] Furthermore, by solving the minimum realization of the above band-pass filter, the state space model of the filter can be obtained, and this process can be expressed as: ; where z f (t ) and y f ( t ) are the state variable and the output variable corresponding to the filter state space model, respectively. J f 、 B f and C f are the system matrix, the input matrix, and the output matrix corresponding to the filter state space model, respectively.

[0063] Further, in the embodiments of the present application, based on the above system matrix, input matrix, output matrix, first eigenvalue matrix, and the block input matrix and block output matrix of the second linear model, the following matrices are calculated: ; Based on the above matrix calculation results, the following form of matrix is calculated: ; Further, in combination with the foregoing calculation results, the following discrete linear time-invariant system can be constructed: ;

[0064] ; Among them, z 1, i ( t ) = z 1( iT ), z f, i ( t ) = z f ( iT ), I represents the identity matrix of an appropriate dimension.

[0065] Even further, in the embodiments of the present application, for the above constructed discrete linear time-invariant system, a corresponding observer-based state feedback control system is designed, and its system model can be expressed as: ; Among them, is the observer state; K is n × n dimensional state feedback matrix, which can make the eigenvalues of ln( – K ) / T be the desired eigenvalues λ, the real parts of which are all less than 0 and far from the imaginary axis; L is n × n dimensional observer matrix, which can make ln( – L ) / T have the absolute value of the real part of the eigenvalue as the expected eigenvalue λ 3 to 10 times the absolute value of the real part.

[0066] In summary, in the embodiments of the present application, the power system electromagnetic oscillation stabilizer mainly includes an input transformation system, an oscillation signal output system, a filter, an output transformation system, and a state feedback control system. Among them, the oscillation signal output system is used to measure the electromagnetic oscillation signal of the external power system, and the comprehensive relational expressions corresponding to the other modules can be expressed as: Input transformation system: ; Filter: ; Output transformation system: ; State feedback control system: ; Thus, a power system linear periodic time-varying electromagnetic oscillation stabilizer can be formed by the above-mentioned modules. After introducing this stabilizer, the eigenvalues of the power system can be changed from λ pd to the expected eigenvalues λ and the eigenvalues of ln( – L ) / T . Since the real parts of the eigenvalues of the above matrix are all less than 0 and far from the imaginary axis, after introducing this stabilizer, the entire power system can have a high stability margin, effectively suppress the electromagnetic oscillation generated during the operation of the power system, and improve the system stability.

[0067] Figure 4 is a schematic diagram of the design process of the power system electromagnetic oscillation stabilizer provided by the embodiments of the present application. As Figure 4 shown, in a specific embodiment of the present application, the design process of the power system electromagnetic oscillation stabilizer includes the following steps: Step S1, establish a linear periodic time-varying model of a power system containing a large number of power electronic devices. The specific form of the model can refer to the content of the foregoing embodiments.

[0068] Step S2, through numerical calculation, determine the state transition matrix Φ( t , 0) of the linear periodic time-varying model of the power system in [0, TValues within the time interval and solve T The state transition matrix Φ( T , 0) of the eigenvalue matrix Q And the eigenvector U (0) and V (0).

[0069] Step S3, calculate the eigenvalue matrix of the linear periodic time-varying system J e , and according to the damping magnitude of the eigenvalues, divide J e Into the first eigenvalue matrix corresponding to negative damping / weak damping J e1 And the second eigenvalue matrix J e2 .

[0070] Step S4, obtain the time-varying matrix U ( t ) and V ( t ) by solving the preset differential equation.

[0071] Step S5, through the transformation formula x ( t ) = U ( t ) z ( t ), transform the aforementioned linear periodic time-varying model into a linear model with J e As the system matrix, that is, obtain the first linear model.

[0072] Step S6, calculate the controllability / observability of different inputs / outputs for J e1 The corresponding eigenvalues, and screen the high-controllability input u 1( t ) and the high-observability output y 1( t ).

[0073] Step S7, based on the controllability / observability analysis results of the first eigenvalue matrix J e1 , simplify the transformed first linear model to obtain a low-order linear model, that is, obtain the third linear model.

[0074] Step S8, based on the aforementioned linear model, block input matrix, block output matrix, output variable and other parameters and the first eigenvalue matrix, construct the system models of the input transformation system and the output transformation system.

[0075] Step S9: Design the aforementioned preset band-pass filter according to the negative damping / weak damping mode information, and obtain the system matrix, input matrix, and output matrix corresponding to the state-space model of the filter.

[0076] Step S10: Calculate the intermediate variable matrix E from 1 to E 3, W from 1 to W 3.

[0077] Step S11: Combine the aforementioned calculation results to construct the discrete linear time-invariant system in the aforementioned embodiment.

[0078] Step S12: Based on the above discrete linear time-invariant system and the desired eigenvalue information, design the system model of the state feedback control system based on the observer.

[0079] Step S13: Integrate the system models of the aforementioned designed input transformation system, oscillation signal output system, filter, output transformation system, and state feedback control system to obtain the linear periodic time-varying electromagnetic oscillation stabilizer for the power system.

[0080] Figure 5 This is the effect schematic diagram of the power system electromagnetic oscillation stabilizer provided by the embodiment of the present application. As Figure 5 shown, an electromagnetic transient simulation model of a certain actual power system is constructed in MATLAB / Simulink. Before the stabilizer is connected, the time-domain waveforms of the output voltage amplitude of a certain photovoltaic power station and the DC-side current of the conventional HVDC transmission both oscillate and diverge; while after the stabilizer of the embodiment of the present application is connected at 6 s (seconds), the oscillation is quickly suppressed. The above electromagnetic transient simulation results verify the effectiveness and reliability of the linear periodic time-varying electromagnetic oscillation stabilizer for the power system provided by the present application.

[0081] It should be understood that the above device is used to execute the method in the above embodiment. For the corresponding program modules in the device, their implementation principles and technical effects are similar to those described in the above method. The working process of the device can refer to the corresponding process in the above method, which will not be elaborated here.

[0082] The method steps in the embodiments of this application can be implemented in a hardware manner or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in a random access memory (RAM), flash memory, read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), register, hard disk, removable hard disk, CD-ROM, or any other form of storage medium well-known in the art. An exemplary storage medium is coupled to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC.

[0083] In the above embodiments, it can be implemented in whole or in part through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of this application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center in a wired manner (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wirelessly (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that the computer can access or a data storage device such as a server or data center that includes one or more integrated available media. The available medium can be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a DVD), or a semiconductor medium (such as a solid state disk (SSD)), etc.

[0084] It can be understood that the various numerical numbers involved in the embodiments of this application are only for the convenience of description and are not used to limit the scope of the embodiments of this application.

[0085] It should be understood that expressions such as "including" and "may include" that can be used in this application indicate the existence of the disclosed functions, operations, or components, and do not limit the existence of one or more additional functions, operations, and components. In this application, terms such as "including" and / or "having" can be interpreted as indicating a specific characteristic, number, operation, component, component, or a combination thereof, but cannot be interpreted as excluding the existence or possibility of addition of one or more other characteristics, numbers, operations, components, components, or a combination thereof.

[0086] As described above, the above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present application can easily think of changes or substitutions, which should be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An electromagnetic oscillation stabilizer for a power system, characterized in that, Comprising: An input transformation system, a state conversion system, and a state feedback control system; The output end of the input transformation system is connected to the input end of an external power system; The input end of the state conversion system is connected to the output end of the external power system, and the output end of the state conversion system is connected to the input end of the state feedback control system; the input end of the input transformation system is connected to the output end of the state feedback control system; The input transformation system is used to determine a target control position where the external power system has a target electromagnetic oscillation mode, so as to obtain an original electromagnetic oscillation signal of the external power system at the target control position; The state conversion system is used to output a target signal related to the eigenvalue of the external power system based on the original electromagnetic oscillation signal generated at the target control position; The state feedback control system is used to measure the target signal and use the target signal to generate a control signal through an observer-based state feedback control law, so that the real part of the eigenvalue of the external power system is negative.

2. The electromagnetic oscillation stabilizer for a power system according to claim 1, characterized in that, The state conversion system includes an oscillation signal output system, a filter, and an output transformation system connected in sequence; the input of the oscillation signal output system serves as the input end of the state conversion system, and the output end of the output transformation system serves as the output end of the state conversion system; The oscillation signal output system is used to obtain the original electromagnetic oscillation signal generated by the external power system at the target control position; The filter is used to filter the original electromagnetic oscillation signal to obtain an electromagnetic oscillation signal in a target frequency band; The output transformation system is used to perform signal conversion on the electromagnetic oscillation signal in the target frequency band and output a target signal related to the eigenvalue of the external power system.

3. A stabilization method applied to the electromagnetic oscillation stabilizer of the power system according to any one of claims 1 or 2, characterized in that, Comprising: The input transformation system determines a target control position where the external power system has a target electromagnetic oscillation mode, so as to obtain an original electromagnetic oscillation signal of the external power system at the target control position; The state conversion system outputs a target signal related to the eigenvalue of the external power system based on the original electromagnetic oscillation signal generated at the target control position; The state feedback control system measures the target signal and uses the target signal to generate a control signal through an observer-based state feedback control law, so that the real part of the eigenvalue of the target power system is negative.

4. The stabilization method according to claim 3, characterized in that, The state conversion system includes an oscillation signal output system, a filter, and an output transformation system connected in sequence; Correspondingly, the state conversion system outputs a target signal related to the eigenvalue of the external power system based on the original electromagnetic oscillation signal generated at the target control position, including: The oscillation signal output system obtains the original electromagnetic oscillation signal generated by the external power system at the target control position; The filter filters the original electromagnetic oscillation signal to obtain an electromagnetic oscillation signal in a target frequency band; The output transformation system performs signal conversion on the electromagnetic oscillation signal in the target frequency band and outputs a target signal related to the eigenvalue of the external power system.

5. The stabilization method according to claim 4, characterized in that, Before the input transformation system determines the target control position of the target electromagnetic oscillation mode in the external power system, the method further includes: Converting the linear periodic time-varying model of the external power system into a first linear model with the eigenvalue matrix of the external power system as the system matrix; Sorting the elements in the system eigenvalue matrix in descending order according to the real part of the eigenvalues, and dividing the sorted eigenvalue matrix into a first eigenvalue matrix and a second eigenvalue matrix; Performing a block input-output transformation on the first linear model by using the first eigenvalue matrix and the second eigenvalue matrix to obtain a second linear model; the second linear model includes a block input matrix and a block output matrix; Based on the controllability and observability analysis results of the first eigenvalue matrix, simplifying the second linear model into a third linear model with the target control position as a variable.

6. The stabilization method according to claim 5, characterized in that, The converting the linear periodic time-varying model of the external power system into a first linear model with the eigenvalue matrix of the external power system as the system matrix includes: Solving the state transition matrix of the linear periodic time-varying model of the external power system to determine the eigenvalue matrix of the state transition matrix, so as to obtain the eigenvalue matrix of the external power system; Determining a periodic time-varying transformation matrix based on the system eigenvalue matrix; Using the periodic time-varying transformation matrix to convert the linear periodic time-varying model into a first linear model with the system eigenvalue matrix as the system matrix.

7. The stabilization method according to claim 5, characterized in that Before the input transformation system determines the target control position of the target electromagnetic oscillation mode in the external power system, the method further includes: Determining the system model of the input transformation system based on the block input matrix of the second linear model and the first eigenvalue matrix.

8. The stabilization method according to claim 5, wherein Before the input transformation system determines the target control position of the target electromagnetic oscillation mode in the external power system, the method further includes: Determining the system model of the output transformation system based on the first eigenvalue matrix, the block output matrix of the second linear model, and the output variable.

9. The stabilization method according to claim 5, characterized in that, Before the input transformation system determines the target control position of the target electromagnetic oscillation mode in the external power system, the method further includes: Obtaining the system matrix, input matrix, and output matrix corresponding to the state space model of the filter; Based on the system matrix, the input matrix, the output matrix, the first eigenvalue matrix, and the block input matrix and block output matrix of the second linear model, constructing a system model of a discrete linear time-invariant system; Based on the discrete linear time-invariant system, determining a system model of a state feedback control system based on an observer.

10. The stabilization method according to claim 9, characterized in that, The obtaining the system matrix, input matrix, and output matrix corresponding to the state space model of the filter includes: Obtaining the system model of a preset band-pass filter; Using the minimum realization method of the band-pass filter to solve the system model of the band-pass filter to obtain the system matrix, input matrix, and output matrix corresponding to the state space model of the filter.

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