CN117200331A - Nonlinear fusion synchronization method and device for converter - Google Patents
Nonlinear fusion synchronization method and device for converter Download PDFInfo
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Abstract
The application relates to a nonlinear fusion synchronization method and device of a converter, wherein the method comprises the following steps: acquiring grid-connected point voltage and grid-connected point current of a target power grid, identifying a power grid short-circuit ratio based on the grid-connected point voltage and the grid-connected point current, and obtaining a follow-up characteristic proportionality coefficient by utilizing the power grid short-circuit ratio; calculating q-axis components and active power of the grid-connected point voltage based on the grid-connected point voltage and the grid-connected point current, obtaining grid-connected point frequency disturbance quantity by using the q-axis components, and obtaining self-synchronous frequency disturbance quantity by using the active power; and carrying out fusion calculation on the following network characteristic proportionality coefficient, the grid-connected point frequency disturbance quantity and the self-synchronous frequency disturbance quantity to obtain a synchronous phase angle of the converter, so as to control the converter to carry out self-adaptive adjustment based on the synchronous phase angle when detecting the change of the following network characteristic proportionality coefficient. Therefore, the technical problems that the power system is not suitable for flexible and changeable working conditions of the power system and has no real-time performance in the related technology, and the safety and stability of the power system are difficult to ensure are solved.
Description
Technical Field
The application relates to the technical field of analysis and control of power systems, in particular to a nonlinear fusion synchronization method and device of a converter.
Background
In an electric power system, a new energy unit is connected into a power grid through a following grid or a grid-structured converter, and broadband oscillation is caused by complex control interaction between the converters and the power grid. The broadband oscillation can cause damage or network disconnection of a new energy unit, shafting torsion crack of a turbine unit and even cause global safety and stability problems, and becomes one of the important technical problems restricting the development of a novel power system.
In order to solve the influence of broadband oscillation on a power system, in the related technology, the broadband oscillation problem can be analyzed by pre-evaluating whether the new energy station generates the broadband oscillation risk during grid connection so as to prevent the new energy station in advance, and building an analysis model and a simulation platform after the broadband oscillation is detected.
However, in the related art, a plurality of working conditions need to be preset in advance to evaluate the broadband oscillation risk in advance, factors with incomplete coverage of the working conditions exist, the method is not suitable for the flexible and changeable conditions of the power system, the broadband oscillation problem is analyzed by establishing an analysis model and setting up a simulation platform, analysis is needed after oscillation occurs, and the real-time performance is not achieved.
In summary, the related technology is not suitable for flexible and changeable working conditions of the power system, and does not have real-time performance, so that the safety and stability of the power system are difficult to ensure, and the improvement is needed.
Disclosure of Invention
The application provides a nonlinear fusion synchronization method and device of a converter, which are used for solving the technical problems that in the related art, the method and device are not suitable for flexible and changeable working conditions of a power system, and do not have instantaneity, so that the safety and stability of the power system are difficult to ensure.
An embodiment of a first aspect of the present application provides a nonlinear fusion synchronization method for a current transformer, including the following steps: acquiring grid-connected point voltage and grid-connected point current of a target power grid, identifying a power grid short-circuit ratio based on the grid-connected point voltage and the grid-connected point current, and obtaining a follow-up characteristic proportionality coefficient by utilizing the power grid short-circuit ratio; calculating q-axis components and active power of the grid-connected point voltage based on the grid-connected point voltage and the grid-connected point current, obtaining grid-connected point frequency disturbance quantity by using the q-axis components, and obtaining self-synchronous frequency disturbance quantity by using the active power; and carrying out fusion calculation on the grid-following characteristic proportionality coefficient, the grid-connected point frequency disturbance quantity and the self-synchronous frequency disturbance quantity to obtain a synchronous phase angle of the converter, so as to control the converter to carry out self-adaptive adjustment based on the synchronous phase angle when the change of the grid-following characteristic proportionality coefficient is detected.
Optionally, in an embodiment of the present application, the obtaining the ratio of the power grid to the grid characteristic by using the power grid short circuit ratio includes: and constructing a mathematical relation equation of the grid short-circuit ratio and the grid-following characteristic proportionality coefficient by utilizing nonlinear hysteresis characteristics, and calculating the grid-following characteristic proportionality coefficient by utilizing the mathematical relation equation.
Optionally, in an embodiment of the present application, the mathematical relationship equation is:
or alternatively, the first and second heat exchangers may be,
wherein SCR represents the power grid short-circuit ratio, delta SCR represents the mixed characteristic short-circuit ratio range, alpha is an independent variable under a polar coordinate system, and SCR high Represents the corresponding short circuit ratio of the power grid when the ratio of the network following characteristics is 1, SCR low Represents the corresponding short circuit ratio of the power grid when the ratio of the follow-up characteristic is 0, r GFL The ratio coefficient of the following net characteristic is represented, and n and m represent constant coefficients.
Optionally, in an embodiment of the present application, the obtaining the ratio of the power grid to the grid characteristic by using the power grid short circuit ratio includes: and matching the corresponding grid following characteristic proportionality coefficient in a preset mathematical relationship comparison table by utilizing the grid short-circuit ratio.
Optionally, in an embodiment of the present application, the calculation formula of the synchronization phase angle is:
wherein θ represents the synchronization phase angle,transfer function representing the integration element, s representing the complex variable in the transfer function, ω 1 Represents an angular frequency reference value, Δω GFL Represents the frequency disturbance quantity of the grid-connected point, delta omega GFM Indicating the amount of self-synchronizing frequency disturbance.
An embodiment of a second aspect of the present application provides a nonlinear fusion synchronization device of a current transformer, including: the acquisition module is used for acquiring grid-connected point voltage and grid-connected point current of a target power grid, identifying a power grid short-circuit ratio based on the grid-connected point voltage and the grid-connected point current, and acquiring a follow-up characteristic proportionality coefficient by utilizing the power grid short-circuit ratio; the computing module is used for computing q-axis components and active power of the grid-connected point voltage based on the grid-connected point voltage and the grid-connected point current, obtaining grid-connected point frequency disturbance quantity by using the q-axis components, and obtaining self-synchronous frequency disturbance quantity by using the active power; and the fusion module is used for carrying out fusion calculation on the grid-following characteristic proportionality coefficient, the grid-connected point frequency disturbance quantity and the self-synchronous frequency disturbance quantity to obtain a synchronous phase angle of the converter, so as to control the converter to carry out self-adaptive adjustment based on the synchronous phase angle when the change of the grid-following characteristic proportionality coefficient is detected.
Optionally, in one embodiment of the present application, the acquiring module includes: and the calculating unit is used for constructing a mathematical relation equation of the grid short-circuit ratio and the grid following characteristic proportionality coefficient by utilizing the nonlinear hysteresis characteristic, and calculating the grid following characteristic proportionality coefficient by utilizing the mathematical relation equation.
Optionally, in an embodiment of the present application, the mathematical relationship equation is:
or alternatively, the first and second heat exchangers may be,
wherein SCR represents the power grid short-circuit ratio, delta SCR represents the mixed characteristic short-circuit ratio range, alpha represents the independent variable under the polar coordinate system, and SCR high Represents the corresponding short circuit ratio of the power grid when the ratio of the network following characteristics is 1, SCR low Represents the corresponding short circuit ratio of the power grid when the ratio of the follow-up characteristic is 0, r GFL The ratio coefficient of the following net characteristic is represented, and n and m represent constant coefficients.
Optionally, in one embodiment of the present application, the acquiring module includes:
and the matching unit is used for matching corresponding grid following characteristic proportionality coefficients in a preset mathematical relationship comparison table by utilizing the grid short-circuit ratio.
Optionally, in an embodiment of the present application, the calculation formula of the synchronization phase angle is:
wherein θ represents the synchronization phase angle,transfer function representing the integration element, s representing the complex variable in the transfer function, ω 1 Represents an angular frequency reference value, Δω GFL Represents the frequency disturbance quantity of the grid-connected point, delta omega GFM Indicating the amount of self-synchronizing frequency disturbance.
An embodiment of a third aspect of the present application provides an electronic device, including: the system comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the program to realize the nonlinear fusion synchronization method of the converter as described in the embodiment.
An embodiment of a fourth aspect of the present application provides a computer readable storage medium storing computer instructions for causing a computer to perform the nonlinear fusion synchronization method of a current transformer according to the above embodiment.
According to the embodiment of the application, the grid short-circuit ratio can be identified according to the grid-connected point voltage and the grid-connected point current of the target grid, so that the grid-following characteristic proportion coefficient is obtained by utilizing the grid short-circuit ratio, the q-axis component and the active power of the grid-connected point voltage are calculated based on the grid-connected point voltage and the grid-connected point current, the grid-connected point frequency disturbance quantity and the self-synchronous frequency disturbance quantity are respectively obtained according to the q-axis component and the active power, the grid-following characteristic proportion coefficient, the grid-connected point frequency disturbance quantity and the self-synchronous frequency disturbance quantity are subjected to fusion calculation, and the synchronous phase angle of the current transformer is obtained, so that when the grid-following characteristic proportion coefficient is detected to change, the current transformer is controlled to carry out self-adaptive adjustment based on the synchronous phase angle, the grid-following and the grid-constructing characteristics of the current transformer can be self-adaptively adjusted according to the grid short-circuit ratio, and the current transformer is ensured to have good oscillation stability under different grid intensities. Therefore, the technical problems that the power system is not suitable for flexible and changeable working conditions of the power system and has no real-time performance in the related technology, and the safety and stability of the power system are difficult to ensure are solved.
Additional aspects and advantages of the application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the application.
Drawings
The foregoing and/or additional aspects and advantages of the application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:
fig. 1 is a flowchart of a nonlinear fusion synchronization method of a current transformer according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a nonlinear hysteresis characteristic in accordance with one embodiment of the present application;
fig. 3 is a schematic diagram of a nonlinear fusion synchronization method of a current transformer according to an embodiment of the present application;
fig. 4 is a flowchart of a method of nonlinear fusion synchronization of a current transformer according to an embodiment of the present application;
fig. 5 is a schematic diagram of a nonlinear fusion synchronization method of a current transformer according to another embodiment of the present application;
fig. 6 is a schematic structural diagram of a nonlinear fusion synchronization device of a current transformer according to an embodiment of the present application;
fig. 7 is a schematic structural diagram of an electronic device according to an embodiment of the present application.
Detailed Description
Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present application and should not be construed as limiting the application.
The nonlinear fusion synchronization method and device of the current transformer are described below with reference to the accompanying drawings. Aiming at the technical problems that in the related technology mentioned in the background art, the method is not suitable for flexible and changeable working conditions of a power system and does not have real-time performance, so that safety and stability of the power system are difficult to ensure, the application provides a nonlinear fusion synchronization method of a converter. Therefore, the technical problems that the power system is not suitable for flexible and changeable working conditions of the power system and has no real-time performance in the related technology, and the safety and stability of the power system are difficult to ensure are solved.
Specifically, fig. 1 is a schematic flow chart of a nonlinear fusion synchronization method of a current transformer according to an embodiment of the present application.
As shown in fig. 1, the nonlinear fusion synchronization method of the converter comprises the following steps:
in step S101, a grid-connected point voltage and a grid-connected point current of a target power grid are obtained, a power grid short-circuit ratio is identified based on the grid-connected point voltage and the grid-connected point current, and a follow-up characteristic proportionality coefficient is obtained by using the power grid short-circuit ratio.
It will be appreciated that the oscillation characteristics of the grid-connected, grid-connected converters have "complementarity", in particular: the follow-up grid converter has the risk of oscillation instability in a weak power grid, and the strong power grid has good oscillation stability; in contrast, the grid-built converter is prone to destabilization in a strong power grid, while its weak power grid is better in stability.
In order to improve broadband oscillation stability of the converter under the complex power grid operation working condition, the embodiment of the application can combine the advantages of the grid-following and grid-constructing control structure so as to realize the integration synchronous control of the grid-following and the grid-constructing.
The embodiment of the application can firstly acquire the grid-connected point voltage u of the target power grid abc And grid-connected point current i abc Thereby utilizing the grid-connected point voltage u abc And grid-connected point current i abc Identifying a grid short circuit ratio SCR, and solving a follow-up characteristic proportionality coefficient r by utilizing the grid short circuit ratio SCR GFL The nonlinear hysteresis characteristic is realized so as to facilitate the subsequent integration of the following network and the networking characteristics.
Optionally, in an embodiment of the present application, obtaining the ratio of the following characteristics by using the power grid short circuit ratio includes: constructing a mathematical relation equation of the short-circuit ratio of the power grid and the proportional coefficient of the network following characteristic by utilizing the nonlinear hysteresis characteristic, and calculating the proportional coefficient of the network following characteristic by utilizing the mathematical relation equation; wherein, the mathematical relation equation is:
or alternatively, the first and second heat exchangers may be,
wherein SCR represents a power grid short-circuit ratio, delta SCR represents a mixed characteristic short-circuit ratio range, alpha represents an independent variable under a polar coordinate system, and SCR high Represents the corresponding short circuit ratio of the power grid when the ratio of the network following characteristics is 1, SCR low Represents the corresponding short circuit ratio of the power grid when the ratio of the follow-up characteristic is 0, r GFL The ratio coefficient of the following net characteristic is represented, and n and m represent constant coefficients.
In the actual implementation process, the embodiment of the application can utilize the nonlinear hysteresis characteristic to construct a mathematical relation equation of the power grid short-circuit ratio and the following-network characteristic proportionality coefficient, so as to generate the following-network characteristic proportionality coefficient r according to the short-circuit ratio SCR GFL 。
Wherein r is GFL Representing the duty ratio of the following net characteristic in the external characteristic of the converter, 1-r GFL The duty cycle of the networking characteristic in the external characteristic of the converter is shown. When the SCR is lower, the occupation of the network characteristic is lower; as SCR increases, the off-grid characteristic duty cycle gradually increases until saturation is reached, i.e. r GFL =1. In addition, to avoid r GFL Is greatly adjusted, r GFL The change in (c) should lag the change in SCR. r is (r) GFL The saturation characteristic and hysteresis of the magnetic material are similar to those of ferromagnetic materials.
Therefore, the embodiment of the application can construct SCR and r by utilizing the nonlinear hysteresis characteristic GFL Is a function of the equation (c). Wherein the nonlinear hysteresis characteristic curve can be shown in FIG. 2, which shows SCR low 、SCR high The specific numerical values of the short circuit ratios of the power grid corresponding to the network characteristic ratio of 0 and 1 can be selected by combining the converter and the power grid conditions. Definition of being located at SCR low With SCR high The short-circuit ratio between the two is a mixed characteristic short-circuit ratio, and the mixed characteristic short-circuit ratio range Δscr expression may be:
ΔSCR＝SCR high -SCR low ，
SCR and r can be obtained based on nonlinear hysteresis characteristics GFL The mathematical relationship equation of (2) is:
wherein alpha is an independent variable under a polar coordinate system, and the value interval is [0,2p ]; n and m are constant coefficients, and hysteresis curves corresponding to different n and m are different. Generally, n has a value of 1, and m may be 1, 3 or 5.
In addition, SCR and r GFL The nonlinear hysteresis characteristic of (2) can also be expressed as
Optionally, in an embodiment of the present application, obtaining the ratio of the following characteristics by using the power grid short circuit ratio includes: and matching corresponding grid following characteristic proportionality coefficients in a preset mathematical relationship comparison table by utilizing the grid short-circuit ratio.
Those skilled in the art can understand that solving the mathematical relation equation of the hysteresis characteristic is time-consuming, and when the actual engineering application is implemented, if the computational force resource is limited, the real-time requirement of the application is difficult to ensure.
In order to save calculation time, the embodiment of the application can also realize nonlinear hysteresis characteristics by using a table look-up method.
Specifically, the embodiment of the application can obtain the following network characteristic proportionality coefficient r corresponding to different SCR according to the mathematical relation equation GFL Storing the data into a preset mathematical relationship comparison table; therefore, in practical application, the reference table is looked up according to the real-time short circuit ratio SCR of the power grid, and the required follow-up characteristic proportion coefficient r is further determined GFL 。
In step S102, a q-axis component and active power of the grid-connected point voltage are calculated based on the grid-connected point voltage and the grid-connected point current, the grid-connected point frequency disturbance quantity is obtained by using the q-axis component, and the self-synchronization frequency disturbance quantity is obtained by using the active power.
As one possible implementation, embodiments of the present application may track the q-axis component u of the grid-tie voltage q And obtaining the frequency disturbance quantity delta omega of the grid-connected point GFL The transfer function may be:
wherein K is pPLL 、K iPLL The proportional gain and the integral gain are synchronous with the network respectively.
The network formation synchronization can obtain self-synchronization frequency disturbance delta omega according to the grid-connected point active power P GFM Implementations include a self-synchronization control method such as droop control and virtual synchronous machine control.
In step S103, the following network characteristic proportionality coefficient, the grid-connected point frequency disturbance quantity and the self-synchronization frequency disturbance quantity are fused and calculated to obtain a synchronous phase angle of the converter, so that when the following network characteristic proportionality coefficient change is detected, the converter is controlled to perform self-adaptive adjustment based on the synchronous phase angle; the calculation formula of the synchronous phase angle is as follows:
wherein θ represents the synchronization phase angle,transfer function representing the integration element, s representing the complex variable in the transfer function, ω 1 Represents an angular frequency reference value, Δω GFL Represents the frequency disturbance quantity of the grid-connected point, delta omega GFM Indicating the amount of self-synchronizing frequency disturbance.
In order to combine the characteristics of network following and network constructing control, in some technologies, network following/network constructing switching control and hybrid synchronous control are proposed.
Specifically, the following network/construction network switching control adopts construction network and following network control in the weak network and the strong network respectively, however, the switching of the control modes can influence the stable operation of the converter and deteriorate the electric energy quality.
The hybrid synchronous control realizes synchronization by adopting a phase-locked loop and a power synchronization link at the same time, thereby ensuring that the converter has the characteristics of network following and network constructing at the same time. However, the duty ratio of the network following and constructing characteristics in the strategy is fixed, and cannot be adjusted in a self-adaptive manner according to the external power grid conditions, so that the strategy is insufficient to adapt to complex and variable power grid operation conditions. Therefore, the self-adaptive adjustment of the following network and the networking characteristics according to the operation conditions of the power grid is particularly important.
In the actual execution process, the embodiment of the application can adaptively fuse the frequency disturbance quantity delta omega of the grid-connected point GFL Self-synchronizing frequency disturbance delta omega GFM And solving the synchronous phase angle theta by integration:
wherein,transfer function representing the integration step, s being the complex variable in the transfer function, ω 1 Is an angular frequency reference value, typically 100 pi.
Based on the fusion step, the embodiment of the application can realize the self-adaptive adjustment of the ratio of the characteristics of the current transformer to the network and the network structure by utilizing the nonlinear hysteresis characteristic, and ensure that the current transformer has good oscillation stability under different power grid intensities.
The working principle of the nonlinear fusion synchronization method of the current transformer according to the embodiment of the present application is described in detail with reference to fig. 2 to 5.
As shown in fig. 3, the principle schematic diagram of the embodiment of the application is shown, and the embodiment of the application can be composed of a grid-following synchronization link, a grid-constructing synchronization link, a short-circuit ratio identification, a nonlinear hysteresis loop and a fusion link, so that the self-adaptive adjustment of the grid-following and grid-constructing characteristic ratio of the converter by utilizing the nonlinear hysteresis loop and the fusion link is realized, and the converter is ensured to have good oscillation stability under different grid intensities.
On the basis of fig. 3, as shown in fig. 4, the embodiment of the application may include the following steps:
step S401: and identifying the short circuit ratio of the power grid according to the grid-connected point voltage and the grid-connected point current of the target power grid, and further solving the follow-up characteristic proportionality coefficient by utilizing the nonlinear hysteresis loop.
The embodiment of the application can construct SCR and r by utilizing nonlinear hysteresis characteristics GFL Is a function of the equation (c). Wherein the nonlinear hysteresis characteristic curve can be shown in FIG. 2, which shows SCR low 、SCR high The specific numerical values of the short circuit ratios of the power grid corresponding to the network characteristic ratio of 0 and 1 can be selected by combining the converter and the power grid conditions. Definition of being located at SCR low With SCR high The short-circuit ratio between the two is a mixed characteristic short-circuit ratio, and the mixed characteristic short-circuit ratio range Δscr expression may be:
ΔSCR＝SCR high -SCR low ，
SCR and r can be obtained based on nonlinear hysteresis characteristics GFL The mathematical relationship equation of (2) is:
wherein alpha is an independent variable under a polar coordinate system, and the value interval is [0,2p ]; n and m are constant coefficients, and hysteresis curves corresponding to different n and m are different. Generally, n has a value of 1, and m may be 1, 3 or 5.
In addition, SCR and r GFL The nonlinear hysteresis characteristic of (2) can also be expressed as
Those skilled in the art can understand that solving the mathematical relation equation of the hysteresis characteristic is time-consuming, and when the actual engineering application is implemented, if the computational force resource is limited, the real-time requirement of the application is difficult to ensure.
In order to save calculation time, the embodiment of the application can also realize nonlinear hysteresis characteristics by using a table look-up method.
Specifically, the embodiment of the application can obtain the following network characteristic proportionality coefficient r corresponding to different SCR according to the mathematical relation equation GFL Storing the data into a preset mathematical relationship comparison table; from the slaveIn practical application, the ratio coefficient r of the required network following characteristic is determined according to the grid real-time short circuit ratio SCR lookup table GFL 。
Step S402: and the frequency disturbance quantity of the grid-connected point and the self-synchronization frequency disturbance quantity are obtained by utilizing the grid-following synchronization link and the grid-constructing synchronization link respectively.
The embodiment of the application can track the q-axis component u of the grid-connected point voltage q And obtaining the frequency disturbance quantity delta omega of the grid-connected point GFL The transfer function may be:
wherein K is pPLL 、K iPLL The proportional gain and the integral gain of the link synchronous with the network are respectively.
The networking synchronization link can acquire self-synchronization frequency disturbance quantity delta omega according to the grid-connected point active power P GfM The implementation mode of the method comprises a self-synchronous control method such as droop control and virtual synchronous machine control, so that the method provided by the embodiment of the application can have the characteristics of both network following and network constructing.
Step S403: and the fusion link utilizes the frequency disturbance quantity of the grid-connected point, the self-synchronous frequency disturbance quantity and the ratio coefficient of the grid-following characteristic to solve the synchronous phase angle of the converter.
The embodiment of the application can adaptively fuse the frequency disturbance quantity delta omega of the grid-connected point GfL Self-synchronizing frequency disturbance delta omega GFM And the synchronous phase angle theta is solved through integration, so that the self-adaptive adjustment of the grid following characteristic and the grid constructing characteristic of the converter according to the short circuit ratio of the power grid is ensured.
The calculation formula of the synchronous phase angle of the converter can be as follows:
wherein,transfer function representing the integration step, s being the complex variable in the transfer function, ω 1 Is an angular frequency reference value, typically 100 pi. Further, in the actual implementation process, the embodiment of the present application may further implement the above steps based on the device structure shown in fig. 5.
As shown in fig. 5, an embodiment of the present application may include: the system comprises a signal solving and collecting module 501, a network following synchronization link module 502, a network constructing synchronization link module 503, a short circuit ratio identifying module 504, a nonlinear hysteresis loop module 505 and a fusion link module 506.
Wherein, the signal solving and acquiring module 501 may be configured to acquire the grid-connected point voltage u of the target power grid abc Grid-connected point current i abc Solving the q-axis component u of the grid-connected point voltage q Active power P.
The network synchronization link module 502 may be configured to utilize u q Generating frequency disturbance quantity delta omega of grid-connected point GFL Thereby the converter has the following net characteristic.
The network synchronization link module 503 may be configured to generate the self-synchronization frequency disturbance quantity Δω using the active power P GFM Thereby the converter has the networking characteristic.
The short ratio identification module 504 may be configured to utilize the grid-tie voltage u abc Grid-connected point current i abc And identifying the grid short circuit ratio SCR.
The nonlinear hysteresis loop module 505 may be used to solve for the following-net characteristic scaling factor r using the short-circuit ratio SCR GFL Thereby realizing nonlinear hysteresis characteristics.
The fusion link module 506 may be configured to utilize the grid-tie point frequency disturbance quantity Δω GFL Self-synchronizing frequency disturbance delta omega GFM And the heel net characteristic proportionality coefficient r GFL And solving a synchronous phase angle theta to ensure that the characteristics of the converter in following the grid and constructing the grid are adaptively adjusted according to the short-circuit ratio of the power grid.
According to the nonlinear fusion synchronization method for the current transformer, provided by the embodiment of the application, the grid short-circuit ratio can be identified according to the grid-connected point voltage and the grid-connected point current of the target grid, so that the grid-following characteristic proportion coefficient is obtained by utilizing the grid short-circuit ratio, the q-axis component and the active power of the grid-connected point voltage are calculated based on the grid-connected point voltage and the grid-connected point current, the grid-connected point frequency disturbance quantity and the self-synchronous frequency disturbance quantity are respectively obtained according to the q-axis component and the active power, fusion calculation is carried out on the grid-following characteristic proportion coefficient, the grid-connected point frequency disturbance quantity and the self-synchronous frequency disturbance quantity, and the synchronous phase angle of the current transformer is obtained, so that when the change of the grid-following characteristic proportion coefficient is detected, the current transformer is controlled to carry out self-adaption adjustment based on the synchronous phase angle, and the grid-following characteristics of the current transformer can be self-adaption adjusted according to the grid short-circuit ratio, and the current transformer can be ensured to have good oscillation stability under different grid intensities. Therefore, the technical problems that the power system is not suitable for flexible and changeable working conditions of the power system and has no real-time performance in the related technology, and the safety and stability of the power system are difficult to ensure are solved.
The nonlinear fusion synchronization device of the current transformer according to the embodiment of the application is described with reference to the accompanying drawings.
Fig. 6 is a block schematic diagram of a nonlinear fusion synchronization device of a current transformer according to an embodiment of the present application.
As shown in fig. 6, the nonlinear fusion synchronization device 60 of the current transformer includes: an acquisition module 601, a calculation module 602 and a fusion module 603.
Specifically, the obtaining module 601 is configured to obtain a grid-connected point voltage and a grid-connected point current of the target power grid, identify a power grid short-circuit ratio based on the grid-connected point voltage and the grid-connected point current, and obtain a follow-up characteristic scaling factor by using the power grid short-circuit ratio.
The calculation module 602 is configured to calculate a q-axis component and active power of the grid-connected point voltage based on the grid-connected point voltage and the grid-connected point current, obtain a grid-connected point frequency disturbance quantity by using the q-axis component, and obtain a self-synchronization frequency disturbance quantity by using the active power.
And the fusion module 603 is configured to perform fusion calculation on the following network characteristic proportionality coefficient, the grid-connected point frequency disturbance quantity and the self-synchronization frequency disturbance quantity, so as to obtain a synchronous phase angle of the converter, so that when detecting the change of the following network characteristic proportionality coefficient, the converter is controlled to perform self-adaptive adjustment based on the synchronous phase angle.
Optionally, in one embodiment of the present application, the acquiring module 601 includes: and a calculation unit.
The calculation unit is used for constructing a mathematical relation equation of the power grid short-circuit ratio and the grid-following characteristic proportionality coefficient by utilizing the nonlinear hysteresis characteristic, and calculating the grid-following characteristic proportionality coefficient by utilizing the mathematical relation equation.
Alternatively, in one embodiment of the application, the mathematical relationship equation is:
or alternatively, the first and second heat exchangers may be,
wherein SCR represents a power grid short-circuit ratio, delta SCR represents a mixed characteristic short-circuit ratio range, alpha represents an independent variable under a polar coordinate system, and SCR high Represents the corresponding short circuit ratio of the power grid when the ratio of the network following characteristics is 1, SCR low Represents the corresponding short circuit ratio of the power grid when the ratio of the follow-up characteristic is 0, r GFL The ratio coefficient of the following net characteristic is represented, and n and m represent constant coefficients.
Optionally, in one embodiment of the present application, the acquiring module 100 includes: and a matching unit.
The matching unit is used for matching corresponding network following characteristic proportionality coefficients in a preset mathematical relationship comparison table by utilizing the power grid short-circuit ratio.
Optionally, in one embodiment of the present application, the calculation formula of the synchronization phase angle is:
wherein θ represents the synchronization phase angle,transfer function representing the integration element, s representing the complex variable in the transfer function, ω 1 Represents an angular frequency reference value, Δω GFL Represents the frequency disturbance quantity of the grid-connected point, delta omega GFM Indicating the amount of self-synchronizing frequency disturbance.
It should be noted that the foregoing explanation of the embodiment of the nonlinear fusion synchronization method of the current transformer is also applicable to the nonlinear fusion synchronization device of the current transformer of this embodiment, and will not be repeated herein.
According to the nonlinear fusion synchronization device of the current transformer, provided by the embodiment of the application, the grid short-circuit ratio can be identified according to the grid-connected point voltage and the grid-connected point current of the target grid, so that the grid-following characteristic proportion coefficient is obtained by utilizing the grid short-circuit ratio, the q-axis component and the active power of the grid-connected point voltage are calculated based on the grid-connected point voltage and the grid-connected point current, the grid-connected point frequency disturbance quantity and the self-synchronous frequency disturbance quantity are respectively obtained according to the q-axis component and the active power, fusion calculation is carried out on the grid-following characteristic proportion coefficient, the grid-connected point frequency disturbance quantity and the self-synchronous frequency disturbance quantity, and the synchronous phase angle of the current transformer is obtained, so that when the change of the grid-following characteristic proportion coefficient is detected, the current transformer is controlled to carry out self-adaptive adjustment based on the synchronous phase angle, and the grid-following characteristics of the current transformer can be self-adaptively adjusted according to the grid short-circuit ratio, and the current transformer can be ensured to have good oscillation stability under different grid intensities. Therefore, the technical problems that the power system is not suitable for flexible and changeable working conditions of the power system and has no real-time performance in the related technology, and the safety and stability of the power system are difficult to ensure are solved.
Fig. 7 is a schematic structural diagram of an electronic device according to an embodiment of the present application. The electronic device may include:
memory 701, processor 702, and computer programs stored on memory 701 and executable on processor 702.
The processor 702 implements the nonlinear fusion synchronization method of the converter provided in the above embodiment when executing the program.
Further, the electronic device further includes:
a communication interface 703 for communication between the memory 701 and the processor 702.
Memory 701 for storing a computer program executable on processor 702.
The memory 701 may include a high-speed RAM memory or may further include a non-volatile memory (non-volatile memory), such as at least one magnetic disk memory.
If the memory 701, the processor 702, and the communication interface 703 are implemented independently, the communication interface 703, the memory 701, and the processor 702 may be connected to each other through a bus and perform communication with each other. The bus may be an industry standard architecture (Industry Standard Architecture, abbreviated ISA) bus, an external device interconnect (Peripheral Component, abbreviated PCI) bus, or an extended industry standard architecture (Extended Industry Standard Architecture, abbreviated EISA) bus, among others. The buses may be divided into address buses, data buses, control buses, etc. For ease of illustration, only one thick line is shown in fig. 7, but not only one bus or one type of bus.
Alternatively, in a specific implementation, if the memory 701, the processor 702, and the communication interface 703 are integrated on a chip, the memory 701, the processor 702, and the communication interface 703 may communicate with each other through internal interfaces.
The processor 702 may be a central processing unit (Central Processing Unit, abbreviated as CPU) or an application specific integrated circuit (Application Specific Integrated Circuit, abbreviated as ASIC) or one or more integrated circuits configured to implement embodiments of the present application.
The present embodiment also provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the nonlinear fusion synchronization method of a current transformer as above.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or N embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, "N" means at least two, for example, two, three, etc., unless specifically defined otherwise.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and additional implementations are included within the scope of the preferred embodiment of the present application in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order from that shown or discussed, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the embodiments of the present application.
Logic and/or steps represented in the flowcharts or otherwise described herein, e.g., a ordered listing of executable instructions for implementing logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or N wires, a portable computer cartridge (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). In addition, the computer readable medium may even be paper or other suitable medium on which the program is printed, as the program may be electronically captured, via optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
It is to be understood that portions of the present application may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, the N steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. As with the other embodiments, if implemented in hardware, may be implemented using any one or combination of the following techniques, as is well known in the art: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like.
Those of ordinary skill in the art will appreciate that all or a portion of the steps carried out in the method of the above-described embodiments may be implemented by a program to instruct related hardware, where the program may be stored in a computer readable storage medium, and where the program, when executed, includes one or a combination of the steps of the method embodiments.
In addition, each functional unit in the embodiments of the present application may be integrated in one processing module, or each unit may exist alone physically, or two or more units may be integrated in one module. The integrated modules may be implemented in hardware or in software functional modules. The integrated modules may also be stored in a computer readable storage medium if implemented in the form of software functional modules and sold or used as a stand-alone product.
The above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, or the like. While embodiments of the present application have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the application, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the application.
Claims (12)
1. The nonlinear fusion synchronization method of the converter is characterized by comprising the following steps of:
acquiring grid-connected point voltage and grid-connected point current of a target power grid, identifying a power grid short-circuit ratio based on the grid-connected point voltage and the grid-connected point current, and obtaining a follow-up characteristic proportionality coefficient by utilizing the power grid short-circuit ratio;
calculating q-axis components and active power of the grid-connected point voltage based on the grid-connected point voltage and the grid-connected point current, obtaining grid-connected point frequency disturbance quantity by using the q-axis components, and obtaining self-synchronous frequency disturbance quantity by using the active power;
and carrying out fusion calculation on the grid-following characteristic proportionality coefficient, the grid-connected point frequency disturbance quantity and the self-synchronous frequency disturbance quantity to obtain a synchronous phase angle of the converter, so as to control the converter to carry out self-adaptive adjustment based on the synchronous phase angle when the change of the grid-following characteristic proportionality coefficient is detected.
2. The method of claim 1, wherein said deriving a ratio of the off-grid characteristics using the grid short ratio comprises: and constructing a mathematical relation equation of the grid short-circuit ratio and the grid-following characteristic proportionality coefficient by utilizing nonlinear hysteresis characteristics, and calculating the grid-following characteristic proportionality coefficient by utilizing the mathematical relation equation.
3. The method of claim 2, wherein the mathematical relationship equation is:
or alternatively, the first and second heat exchangers may be,
wherein SCR represents the power grid short-circuit ratio, delta SCR represents the mixed characteristic short-circuit ratio range, alpha represents the independent variable under the polar coordinate system, and SCR high Represents the corresponding short circuit ratio of the power grid when the ratio of the network following characteristics is 1, SCR low Represents the corresponding short circuit ratio of the power grid when the ratio of the follow-up characteristic is 0, r GFL The ratio coefficient of the following net characteristic is represented, and n and m represent constant coefficients.
4. The method of claim 1, wherein said deriving a ratio of the off-grid characteristics using the grid short ratio comprises:
and matching the corresponding grid following characteristic proportionality coefficient in a preset mathematical relationship comparison table by utilizing the grid short-circuit ratio.
5. The method of claim 1, wherein the synchronization phase angle is calculated by the formula:
wherein θ represents the synchronization phase angle,transfer function representing the integration element, s representing the complex variable in the transfer function, ω 1 Represents an angular frequency reference value, Δω GFL Represents the frequency disturbance quantity of the grid-connected point, delta omega GFM Indicating the amount of self-synchronizing frequency disturbance.
6. A non-linear fusion synchronization device for a current transformer, comprising:
the acquisition module is used for acquiring grid-connected point voltage and grid-connected point current of a target power grid, identifying a power grid short-circuit ratio based on the grid-connected point voltage and the grid-connected point current, and acquiring a follow-up characteristic proportionality coefficient by utilizing the power grid short-circuit ratio;
the computing module is used for computing q-axis components and active power of the grid-connected point voltage based on the grid-connected point voltage and the grid-connected point current, obtaining grid-connected point frequency disturbance quantity by using the q-axis components, and obtaining self-synchronous frequency disturbance quantity by using the active power;
and the fusion module is used for carrying out fusion calculation on the grid-following characteristic proportionality coefficient, the grid-connected point frequency disturbance quantity and the self-synchronous frequency disturbance quantity to obtain a synchronous phase angle of the converter, so as to control the converter to carry out self-adaptive adjustment based on the synchronous phase angle when the change of the grid-following characteristic proportionality coefficient is detected.
7. The apparatus of claim 6, wherein the acquisition module comprises:
and the calculating unit is used for constructing a mathematical relation equation of the grid short-circuit ratio and the grid following characteristic proportionality coefficient by utilizing the nonlinear hysteresis characteristic, and calculating the grid following characteristic proportionality coefficient by utilizing the mathematical relation equation.
8. The apparatus of claim 7, wherein the mathematical relationship equation is:
or alternatively, the first and second heat exchangers may be,
wherein SCR represents the power grid short-circuit ratio, delta SCR represents the mixed characteristic short-circuit ratio range, alpha represents the independent variable under the polar coordinate system, and SCR high Represents the corresponding short circuit ratio of the power grid when the ratio of the network following characteristics is 1, SCR low Represents the corresponding short circuit ratio of the power grid when the ratio of the follow-up characteristic is 0, r GFL The ratio coefficient of the following net characteristic is represented, and n and m represent constant coefficients.
9. The apparatus of claim 6, wherein the acquisition module comprises:
and the matching unit is used for matching corresponding grid following characteristic proportionality coefficients in a preset mathematical relationship comparison table by utilizing the grid short-circuit ratio.
10. The apparatus of claim 6, wherein the synchronization phase angle is calculated by the formula:
wherein θ represents the synchronization phase angle,transfer function representing the integration element, s representing the complex variable in the transfer function, ω 1 Represents an angular frequency reference value, Δω GFL Represents the frequency disturbance quantity of the grid-connected point, delta omega GFM Indicating the amount of self-synchronizing frequency disturbance.
11. An electronic device, comprising: a memory, a processor and a computer program stored on the memory and executable on the processor, the processor executing the program to implement the method of non-linear fusion synchronization of a current transformer according to any one of claims 1-5.
12. A computer readable storage medium having stored thereon a computer program, characterized in that the program is executed by a processor for implementing a non-linear fusion synchronization method of a current transformer according to any of claims 1-5.
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