New energy station oscillation precise traceability and emergency control method and storage medium

Abstract

The invention discloses a new energy station oscillation precise traceability and emergency control method and a storage medium. The method comprises the steps of performing frequency sweeping to obtain impedance data of a new energy station and a large power grid under different working conditions; a new energy station oscillation emergency control structure and a control parameter selection method are provided; according to real-time monitoring results of tidal currents of all nodes in the new energy grid-connected system, working conditions of new energy equipment and a large power grid are judged on line, impedance under the corresponding working conditions is extracted for oscillation mode judgment, key mode information under the current working condition is obtained, and the optimal controllable observable node position under the current working condition is obtained; and when the oscillation mode judgment result is that the oscillation risk exists, adding an emergency controller in a control loop of the new energy equipment of the optimal controllable observable node. According to the new energy station oscillation accurate traceability and emergency control method and system provided by the invention, resonance risk and damped oscillation risk modes of a new energy grid-connected system can be responded online, and the operation stability of the new energy station is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a method and storage medium for accurate tracing and emergency control of oscillations in a new energy station. Background Art

[0002] The large-scale access of new energy equipment to the power grid has made the multi-modal weak damping characteristics of the new power system significant. The modal diversity characteristics have led to an increasingly serious risk of multi-band oscillations in the new power system. Since the geographical locations of my country's new energy bases and load centers are inversely distributed, large-scale new energy transmission via high-voltage AC and DC has become the norm, which has aggravated the complexity of the power system grid. The short-circuit ratio of the power grid varies greatly under complex working conditions. In addition, the external characteristics change under the random fluctuations of new energy output. The stability of the new energy grid-connected system has become increasingly critical. Assessing the potential multi-band oscillation risks of the power system under different operating conditions is crucial to ensuring the safe and stable operation of the new power system.

[0003] The increase in the penetration rate of new energy in the new power system has highlighted the weak damping characteristics of the system. The negative resistance effect and capacitive effect of power electronic equipment have further reduced the modal damping ratio. After a large number of power electronic equipment are connected to the large power grid, the oscillation mode increases, the modal analysis becomes more difficult, and the oscillation risk of the new energy power system increases. The oscillation problem has become an important factor endangering the stable operation of new energy sites.

[0004] In addition, due to the rapid propagation speed of oscillations, in order to avoid the expansion of the impact range, the oscillation control strategy must be formulated in a short time, which is relatively difficult in actual operation. There are relatively few existing research programs for accurate tracing and emergency control of oscillations, and they are mainly offline tracing programs. There are few studies based on real-time monitoring data to conduct oscillation tracing and apply emergency control measures. In summary, the existing research programs cannot meet the emergency control needs of new energy site oscillations, and it is difficult to ensure the stable operation of new energy power systems.

[0005] Therefore, it is necessary to study a method and storage medium for accurate tracing and emergency control of oscillations in new energy stations, design an accurate tracing method and an emergency control strategy for oscillations, and provide a feasible solution for accurate tracing and emergency control of oscillations in new energy stations. Summary of the invention

[0006] In order to solve the above-mentioned problems in the prior art, the present invention provides a method and system for accurate tracing and emergency control of oscillations in new energy stations, which aims to accurately trace the oscillations in new energy stations, while suppressing the propagation of oscillations in new energy stations, improving the oscillation modal damping ratio, and ensuring the safe and stable operation of new energy stations.

[0007] In order to achieve the above-mentioned invention object, the present invention provides a method and system for accurately tracing the source of oscillation and emergency control of a new energy station, including a method for accurately tracing the source of oscillation and emergency control of a new energy station, characterized in that it includes the following steps:

[0008] Step 1: Sweep the frequency to obtain and store the impedance data of each power electronic device in the new energy station in the new energy grid-connected system under different working conditions, and sweep the frequency to obtain and store the impedance data of the large power grid under different working conditions;

[0009] Step 2: Design the control structure of the new energy oscillation emergency controller, define the key modal stability index, traverse the optimal parameters of the emergency controller based on the maximization of the modal stability index, and adjust the new energy oscillation emergency controller with the optimal parameters;

[0010] Step 3: Based on the real-time monitoring results of the power flow at each node in the new energy grid-connected system, the working conditions of the new energy equipment and the large power grid are judged online, and the impedance of the large power grid and each new energy device under the corresponding working conditions is extracted from the impedance data obtained by the frequency sweep;

[0011] Step 4: Combine the extracted impedance under the current working condition to identify the oscillation mode, obtain the key mode information under the current working condition, and obtain the best controllable and observable node position under the current working condition;

[0012] Step 5: When it is determined that there is no oscillation risk under the current working condition according to the oscillation mode identification result, continue to monitor the power flow of each node in the new energy grid-connected system in real time;

[0013] Step 6: When it is determined that there is an oscillation risk according to the oscillation mode discrimination result, an emergency controller is added to the control loop of the new energy equipment of the best controllable and observable node;

[0014] Step 7: Improve the damping of key modes and suppress oscillation according to the additional emergency controller.

[0015] Furthermore, the grid connection point is selected as the harmonic signal injection point, the harmonic voltage source is selected as the signal source, the harmonic injection amplitude is set according to the response voltage of the real-time injected harmonic voltage, and the harmonic signal amplitude is selected as 10% of the response harmonic voltage amplitude;

[0016] Furthermore, the oscillation emergency control structure includes a proportional link, a bandpass filter link, a phase correction link and a limit link, and the four links are cascaded to form an oscillation emergency controller, the controller input signal is the dq axis component of the AC voltage, and the controller additional position is the input end of the current inner loop control;

[0017] The transfer function expression of the controller is:

[0018]

[0019]

[0020]

[0021] Among them G F (s) is the transfer function of the bandpass filter link, which is composed of a first-order low-pass filter link and a first-order high-pass filter link in cascade, z is the damping ratio of the bandpass filter, ω0 is the cutoff frequency of the bandpass filter, and s is the Laplace operator. PC (s) is the transfer function of the phase correction link, which includes two cascaded phase correction controllers, T1 is the upper limit cut-off time constant of the phase correction controller, T2 is the lower limit cut-off time constant of the phase correction controller, and s is the Laplace operator. G(s) is the transfer function of the oscillation emergency control structure, K G is the proportional coefficient of the proportional link.

[0022] Furthermore, the cutoff frequency ω0 in the bandpass filtering link, the upper limit cutoff time constant T1 in the phase correction link, and the lower limit cutoff time constant T2 are set to satisfy the relationship:

[0023]

[0024]

[0025] where ω b is the bandwidth angular frequency, which characterizes the correction range of the phase correction link. The bandwidth angular frequency ω is selected b and the proportional coefficient K of the proportional link G As the control variable, the objective function Q is set to the negative of the real part of the characteristic root corresponding to the key mode. The objective function Q is:

[0026] Q=-Re(λ critical )

[0027] where λ critical It is the characteristic root with the largest real part among all characteristic roots, that is, the key characteristic root, also known as the key oscillation mode, and Re() is the algorithm for taking the real part.

[0028] Traverse when ω b and K G When Q takes the maximum value, the real part of the key modal characteristic root is in the left half plane and is farthest from the imaginary axis. The control parameters at this time are the optimal control parameters of the selected emergency control:

[0029] Furthermore, based on the online monitoring device, the current working conditions of the large power grid and the new energy equipment are judged, and based on the stored impedance data of the large power grid under different working conditions acquired by the sweep frequency, and the stored impedance data of each new energy equipment in the new energy station under different working conditions acquired by the sweep frequency, the impedance data of the large power grid and the new energy station under the current working conditions are extracted.

[0030] Furthermore, according to the extracted impedance data of each unit of the new energy grid-connected system under the current operating conditions, a node admittance matrix of the new energy grid-connected system is established based on the impedance data, the oscillation mode is calculated based on the node admittance matrix, the key oscillation mode is judged based on the frequency domain characteristics of the oscillation mode, and whether there is an oscillation risk is judged based on the position of the real part of the key mode in the complex plane. If the real part of the key mode is in the left half plane, there is an oscillation risk, and if the real part of the key mode is in the right half plane, there is no oscillation risk.

[0031] Furthermore, the modal analysis method is used to obtain the key modes under the current working conditions, and the left and right eigenvectors of the key modes are calculated. The participation factor of the key mode at each node is calculated based on the left and right eigenvectors, and the node with the largest participation factor is the best controllable and observable node.

[0032] The node admittance matrix contains the system oscillation mode information. The relationship between the power system node voltage and node current is:

[0033] I=YU

[0034]

[0035] Where n is the number of nodes in the power system, which is also the order of the node admittance matrix, U is the node voltage, and I is the node injection current. The node admittance matrix in the above formula is diagonalized:

[0036]

[0037] In the above formula, L is the left eigenvector matrix, whose row vector is the left eigenvector of the node admittance matrix Y, Λ is the characteristic matrix, whose diagonal elements are the eigenvalues ​​of the node admittance matrix Y, and V is the right eigenvector matrix, whose column vector is the right eigenvector of the node admittance matrix Y. The diagonal elements of the characteristic matrix Λ represent the modal information of each node. When the value of the diagonal elements of Λ is close to 0, the corresponding mode is the key oscillation mode.

[0038] Furthermore, the step of obtaining the best controllable and observable node of the key mode of oscillation in step four is: obtaining the key mode under the current working condition by the modal analysis method, calculating the left and right eigenvectors of the key mode, and calculating the participation factor of the key mode at each node based on the left and right eigenvectors. The node with the largest participation factor is the best controllable and observable node.

[0039] In particular, for the i-th oscillation mode, the participation factor is calculated as:

[0040]

[0041] Where L is the left eigenvector matrix, whose row vector is the left eigenvector of the node admittance matrix Y, and V is the right eigenvector matrix, whose column vector is the right eigenvector of the node admittance matrix Y. PF i is the participation factor corresponding to the i-th oscillation mode.

[0042] Furthermore, the basis for judging whether there is an oscillation risk in steps five and six is: judging whether there is an oscillation risk according to the position of the real part of the key mode in the complex plane, if the real part of the key mode is in the left half plane, there is an oscillation risk, and if the real part of the key mode is in the right half plane, there is no oscillation risk. Based on the oscillation mode discrimination result, when it is judged that there is no oscillation risk under the current working condition, the current of each node in the new energy grid-connected system continues to be monitored in real time; when it is judged that there is an oscillation risk, an emergency controller is added to the control loop of the new energy equipment of the best controllable and observable node.

[0043] Furthermore, the invention includes a storage medium, characterized in that it includes a stored program, and when the program is running, it controls the device where the storage medium is located to execute any of the above-mentioned methods for precise tracing and emergency control of oscillations in new energy stations.

[0044] Based on the oscillation mode identification result, when it is judged that there is no oscillation risk under the current working conditions, continue to monitor the current of each node in the new energy grid-connected system in real time; based on the oscillation mode identification result, when it is judged that there is an oscillation risk, add an emergency controller in the control loop of the new energy equipment of the best controllable and observable node.

[0045] The beneficial effects of the present invention are as follows: the present invention can accurately trace the source of and urgently control the oscillations in the new energy stations, help industry personnel obtain the modal information of the new energy grid-connected system in real time, and when there is an oscillation risk, can quickly control the oscillation at the lowest cost, suppress the propagation of the oscillation in the new energy stations, improve the oscillation modal damping ratio, and ensure the safe and stable operation of the new energy stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0047] Figure 1 This is a flow chart of the method for accurate tracing and emergency control of oscillations in new energy stations of the present invention;

[0048] Figure 2This is a flow chart of the precise tracing and emergency control system for oscillations in new energy stations of the present invention;

[0049] Figure 3 A topological diagram of a new energy grid-connected system in an embodiment of the present invention;

[0050] Figure 4 It is a schematic diagram of the structure of a controller in which an emergency controller in an embodiment of the present invention is attached to a control loop of an inverter of a new energy device;

[0051] Figure 5 Schematic diagram of the feasible domain of control parameters of the emergency controller in an embodiment of the present invention;

[0052] Figure 6 A schematic diagram of the change of the system oscillation mode before and after the emergency control is applied in an embodiment of the present invention;

[0053] Figure 7 This is a comparison diagram of impedance characteristics of a power grid and a new energy station before and after applying emergency control in an embodiment of the present invention;

[0054] Figure 8 A Nyquist curve diagram of the ratio of the grid impedance to the new energy station impedance before and after the emergency control is applied in an embodiment of the present invention;

[0055] Fig. 9 The time domain simulation results of the three-phase current and active power of the grid connection point before and after the emergency control is applied in the embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to clearly illustrate the technical features of this solution, this solution is described below through a specific implementation method.

[0057] See also Figure 1 and Figure 2 The embodiment of the present invention provides a method and system for accurate tracing and emergency control of oscillations in a new energy station, including the following steps:

[0058] based on Figure 3 The new energy grid-connected system shown in the figure obtains and stores the impedance data of each new energy device in the new energy station under different working conditions by frequency sweeping, and obtains and stores the impedance data of the large power grid under different working conditions by frequency sweeping; specifically:

[0059] The method for frequency sweeping of new energy equipment and large power grid is as follows: select the grid connection point of new energy power system as the harmonic injection point of large power grid frequency sweeping, drill the grid connection point of new energy equipment as the harmonic injection point of frequency sweeping of each equipment in new energy station, select the harmonic voltage source as the signal source, set the harmonic injection amplitude according to the response voltage of the real-time injected harmonic voltage, and keep the harmonic signal amplitude at 10% of the response harmonic voltage amplitude at all times;

[0060] In particular, the amplitude of the response harmonic voltage is obtained through Fourier transform. Assuming that the current injected harmonic frequency is f, the component with the frequency f after Fourier transform is extracted, and the amplitude of this component is the amplitude of the response harmonic voltage. The frequency sweeping step under this method ensures that the injected harmonic signal can always cause 10% voltage distortion by monitoring the real-time response of the injected harmonic, which effectively reduces the frequency sweeping error;

[0061] Based on the new energy grid-connected system, a new energy station oscillation emergency control structure and control parameter selection method are proposed; specifically:

[0062] The oscillation emergency control structure includes a proportional link, a bandpass filter link, a phase correction link and a limit link. The four links are cascaded to form an oscillation emergency controller. The controller input signal is the dq axis component of the AC voltage. The controller additional position is the input end of the current inner loop control.

[0063] The bandpass filter link is composed of a first-order low-pass filter link and a first-order high-pass filter link in cascade, and its transfer function G F The expression of (s) is:

[0064]

[0065] Where z is the damping ratio of the bandpass filter, ω0 is the cutoff frequency of the bandpass filter, and s is the Laplace operator.

[0066] The phase correction link includes two phase correction controllers connected in cascade, and the transfer function G PC The expression of (s) is:

[0067]

[0068] Wherein T1 is the upper limit cut-off time constant of the phase correction controller, and T2 is the lower limit cut-off time constant of the phase correction controller.

[0069] The transfer function G(s) of the oscillation emergency control structure is:

[0070]

[0071] Where K G is the proportional coefficient of the proportional link.

[0072] In this embodiment, the emergency controller is attached to the controller structure diagram in the inverter control loop of the new energy equipment as shown in Figure 4 As shown;

[0073] Furthermore, the steps of establishing a control parameter selection method for emergency control are:

[0074] The cutoff frequency ω0 in the bandpass filter link, the upper limit cutoff time constant T1 in the phase correction link, and the lower limit cutoff time constant T2 satisfy the relationship:

[0075]

[0076]

[0077] where ω b is the bandwidth angular frequency, which characterizes the correction range of the phase correction link. The bandwidth angular frequency ω is selected b and the proportional coefficient K of the proportional link G As the control variable, the objective function Q is set to the negative of the real part of the characteristic root corresponding to the key mode. The objective function Q is:

[0078] Q=-Re(λ critical )

[0079] where λ critical It is the characteristic root with the largest real part among all characteristic roots, that is, the key characteristic root, also known as the key oscillation mode, and Re() is the algorithm for taking the real part.

[0080] Traverse when ω b and K G When Q takes the maximum value, the real part of the key modal characteristic root is in the left half plane and is farthest from the imaginary axis. The control parameters at this time are the optimal control parameters of the selected emergency control:

[0081] The schematic diagram of the feasible domain of the control parameters of the emergency controller in this embodiment is as follows: Figure 5 As shown, the x-axis is the parameter, the y-axis is the parameter, and the z-axis is the objective function Q. When the objective function Q reaches the maximum value, the control effect of the emergency controller under this control parameter combination is optimal.

[0082] Based on the real-time monitoring results of the power flow at each node in the new energy grid-connected system, the working conditions of the new energy equipment and the large power grid are judged online, and the impedance of the large power grid and each new energy device under the corresponding working conditions is extracted from the impedance data obtained by the frequency sweep; specifically:

[0083] The current working conditions of the large power grid and new energy equipment are judged based on the online monitoring device. Based on the stored impedance data of the large power grid under different working conditions acquired by frequency scanning and the stored impedance data of each new energy equipment in the new energy station under different working conditions acquired by frequency scanning, the impedance data of the large power grid and the new energy station under the current working conditions are extracted.

[0084] Based on the extracted impedance under the current working condition, the oscillation mode is identified, and the key mode information under the current working condition is obtained, and the optimal controllable and observable node position under the current working condition is obtained; specifically:

[0085] Based on the extracted impedance data of each unit of the new energy grid-connected system under the current operating conditions, the node admittance matrix of the new energy grid-connected system is established based on the impedance data, the oscillation mode is calculated based on the node admittance matrix, the key oscillation mode is judged based on the frequency domain characteristics of the oscillation mode, and whether there is an oscillation risk is judged based on the position of the real part of the key mode in the complex plane. If the real part of the key mode is in the left half plane, there is an oscillation risk, and if the real part of the key mode is in the right half plane, there is no oscillation risk.

[0086] The relationship between the node admittance matrix and the system oscillation mode can be proved as follows. The relationship between the node voltage and node current of the power system is:

[0087] I=YU

[0088]

[0089] Where n is the number of nodes in the power system, which is also the order of the node admittance matrix, U is the node voltage, and I is the node injection current. The node admittance matrix in the above formula is diagonalized:

[0090]

[0091] In the above formula, L is the left eigenvector matrix, whose row vector is the left eigenvector of the node admittance matrix Y, Λ is the characteristic matrix, whose diagonal elements are the eigenvalues ​​of the node admittance matrix Y, and V is the right eigenvector matrix, whose column vector is the right eigenvector of the node admittance matrix Y. The diagonal elements of the characteristic matrix Λ represent the modal information of each node. When the value of the diagonal elements of Λ is close to 0, the corresponding mode is the key oscillation mode.

[0092] The steps to obtain the best controllable and observable nodes of the key modes of oscillation are:

[0093] The modal analysis method is used to obtain the key modes under the current working condition, calculate the left and right eigenvectors of the key modes, and calculate the participation factor of the key mode at each node based on the left and right eigenvectors. The node with the largest participation factor is the best controllable and observable node.

[0094] For the i-th oscillation mode, its participation factor is calculated as:

[0095]

[0096] When it is determined that there is no oscillation risk under the current working condition based on the oscillation mode identification result, the power flow of each node in the new energy grid-connected system continues to be monitored in real time;

[0097] Based on the oscillation mode discrimination result, when it is determined that there is an oscillation risk, an emergency controller is added to the control loop of the new energy equipment of the best controllable and observable node;

[0098] According to the additional emergency controller, the damping of the critical modes is improved and the oscillation is suppressed.

[0099] The schematic diagram of the system oscillation mode change before and after emergency control is applied is shown in Figure 6 As shown in the figure, the three modes in the figure all move to the left half plane of the complex plane after the emergency control is applied, the modal damping is improved, and the movement of the key mode closest to the imaginary axis is the most obvious;

[0100] The impedance characteristics comparison of the power grid and the new energy station before and after the emergency control is applied is shown in the figure below: Figure 7 As shown, it can be seen that the phase difference of the network source impedance at the critical modal frequency before emergency control is 185.4°, and the phase margin is -5.4°. After emergency control, the phase difference of the network source impedance at the critical modal frequency becomes 154.6°, and the phase margin becomes 25.4°. The emergency control improves the phase margin of the new energy grid-connected system. The conclusion is consistent with the conclusion of modal analysis.

[0101] The Nyquist curve of the ratio of grid impedance to new energy station impedance before and after emergency control is applied is as follows: Figure 8 As shown, it can be seen that the Nyquist curve of the ratio of network source impedance before emergency control surrounds the point (-1, j0) counterclockwise and is located within the safety margin circle. The Nyquist curve of the ratio of network source impedance after emergency control no longer surrounds the point (-1, j0), but is far away from the point (-1, j0), indicating that the stability margin of the new energy grid-connected system is improved;

[0102] The time domain simulation results of the active power and three-phase current of the grid connection point before and after the emergency control are as follows: Fig. 9 As shown in the figure, the feasibility of emergency control to suppress oscillation is verified from the time domain simulation level.

[0103] Specifically, the modal information before and after applying emergency control is shown in Table 1:

[0104] Table 1

[0105]

[0106] It can be seen that after applying emergency control to the new energy station, the oscillation mode damping ratio corresponding to each resonant frequency has increased, the key mode has the largest increase, the propagation of oscillation in the new energy station has been suppressed, and the emergency control has improved the stability of the new energy station.

[0107] The system embodiment described above is merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art may understand and implement it without creative work.

[0108] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0109] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for accurate tracing and emergency control of oscillations in new energy stations, characterized in that: The following steps are involved: Step 1: Sweep the frequency to obtain and store the impedance data of each power electronic device in the new energy station in the new energy grid-connected system under different working conditions, and sweep the frequency to obtain and store the impedance data of the large power grid under different working conditions; Step 2: Design the control structure of the new energy oscillation emergency controller, define the key modal stability index, traverse the optimal parameters of the emergency controller based on the maximization of the modal stability index, and adjust the new energy oscillation emergency controller with the optimal parameters; Step 3: Based on the real-time monitoring results of the power flow at each node in the new energy grid-connected system, the working conditions of the new energy equipment and the large power grid are judged online, and the impedance of the large power grid and each new energy device under the corresponding working conditions is extracted from the impedance data obtained by the frequency sweep; Step 4: Combine the extracted impedance under the current working condition to identify the oscillation mode, obtain the key mode information under the current working condition, and obtain the best controllable and observable node position under the current working condition; Step 5: When it is determined that there is no oscillation risk under the current working condition according to the oscillation mode identification result, continue to monitor the power flow of each node in the new energy grid-connected system in real time; Step 6: When it is determined that there is an oscillation risk according to the oscillation mode discrimination result, an emergency controller is added to the control loop of the new energy equipment of the best controllable and observable node; Step 7: Improve the damping of key modes and suppress oscillation according to the additional emergency controller.

2. According to claim 1, a new energy station oscillation precise tracing and emergency control method is characterized in that: The step one also includes the following steps: The grid connection point is selected as the harmonic signal injection point, the harmonic voltage source is selected as the signal source, the harmonic injection amplitude is set according to the response voltage of the real-time injected harmonic voltage, and the harmonic signal amplitude is selected as 10% of the response harmonic voltage amplitude.

3. The method for accurate tracing and emergency control of oscillations of new energy stations according to claim 1 is characterized in that: The step 2 also includes the following steps: The oscillation emergency control structure includes a proportional link, a bandpass filter link, a phase correction link and a limit link. The four links are cascaded to form an oscillation emergency controller. The controller input signal is the dq axis component of the AC voltage. The controller additional position is the input end of the current inner loop control. The transfer function expression of the controller is: Among them G F (s) is the transfer function of the bandpass filter link, which is composed of a first-order low-pass filter link and a first-order high-pass filter link cascaded, z is the damping ratio of the bandpass filter, ω0 is the cutoff frequency of the bandpass filter, s is the Laplace operator, where G PC (s) is the transfer function of the phase correction link, the phase correction link includes two phase correction controllers cascaded to each other, T1 is the upper limit cut-off time constant of the phase correction controller, T2 is the lower limit cut-off time constant of the phase correction controller, s is the Laplace operator, G(s) is the transfer function of the oscillation emergency control structure, K G is the proportional coefficient of the proportional link.

4. The method for accurate tracing and emergency control of oscillations of new energy stations according to claim 1 is characterized in that: The step 2 also includes the following steps: The cutoff frequency ω0 in the bandpass filter link, the upper limit cutoff time constant T1 in the phase correction link, and the lower limit cutoff time constant T2 satisfy the relationship: where ω b is the bandwidth angular frequency, which characterizes the correction range of the phase correction link. The bandwidth angular frequency ω is selected b and the proportional coefficient K of the proportional link G As the control variable, the objective function Q is set to the negative of the real part of the characteristic root corresponding to the key mode. The objective function Q is: Q=-Re(λ critical ) where λ critical It is the characteristic root with the largest real part among all characteristic roots, that is, the key characteristic root, also known as the key oscillation mode, and Re() is the algorithm for taking the real part; Traverse when ω b and K G When Q takes the maximum value, the real part of the key modal characteristic root is in the left half plane and is farthest from the imaginary axis. The control parameters at this time are the optimal control parameters of the selected emergency control.

5. The method for accurate tracing and emergency control of oscillations of new energy stations according to claim 1 is characterized in that: The step three also includes the following steps: The current working conditions of the large power grid and new energy equipment are judged based on the online monitoring device. Based on the stored impedance data of the large power grid under different working conditions acquired by frequency scanning and the stored impedance data of each new energy equipment in the new energy station under different working conditions acquired by frequency scanning, the impedance data of the large power grid and the new energy station under the current working conditions are extracted.

6. The method for accurate tracing and emergency control of oscillations of new energy stations according to claim 1 is characterized in that: The step 4 also includes the following steps: According to the extracted impedance data of each unit of the new energy grid-connected system under the current operating conditions, the node admittance matrix of the new energy grid-connected system is established based on the impedance data, the oscillation mode is calculated based on the node admittance matrix, the key oscillation mode is judged based on the frequency domain characteristics of the oscillation mode, the left and right eigenvectors of the key mode are calculated, and the participation factor of the key mode at each node is calculated based on the left and right eigenvectors. The node with the largest participation factor is the best controllable and observable node.

7. The method for accurate tracing and emergency control of oscillations of new energy stations according to claim 1 is characterized in that: The step 4 also includes the following steps: The node admittance matrix contains the system oscillation mode information. The relationship between the power system node voltage and node current is: I=YU Where n is the number of nodes in the power system, which is also the order of the node admittance matrix, U is the node voltage, and I is the node injection current. The node admittance matrix in the above formula is diagonalized: In the above formula, L is the left eigenvector matrix, whose row vector is the left eigenvector of the node admittance matrix Y, Λ is the characteristic matrix, whose diagonal elements are the eigenvalues ​​of the node admittance matrix Y, V is the right eigenvector matrix, whose column vector is the right eigenvector of the node admittance matrix Y, and the diagonal elements of the characteristic matrix Λ represent the modal information of each node. When the value of the diagonal elements of Λ is close to 0, the corresponding mode is the key oscillation mode.

8. The method for accurate tracing and emergency control of oscillations in new energy stations according to claim 1 is characterized in that: The step 4 also includes the following steps: The steps of obtaining the best controllable and observable node of the key mode of oscillation are: obtaining the key mode under the current working condition by the modal analysis method, calculating the left and right eigenvectors of the key mode, and calculating the participation factor of the key mode at each node based on the left and right eigenvectors, and the node with the largest participation factor is the best controllable and observable node; In particular, for the i-th oscillation mode, the participation factor is calculated as: Where L is the left eigenvector matrix, whose row vector is the left eigenvector of the node admittance matrix Y, V is the right eigenvector matrix, whose column vector is the right eigenvector of the node admittance matrix Y, PF i is the participation factor corresponding to the i-th oscillation mode.

9. The method for accurate tracing and emergency control of oscillations of new energy stations according to claim 1 is characterized in that: The steps five and six also include the following steps: The basis for judging whether there is an oscillation risk is as follows: judging whether there is an oscillation risk according to the position of the real part of the key mode in the complex plane; if the real part of the key mode is in the left half plane, there is an oscillation risk; if the real part of the key mode is in the right half plane, there is no oscillation risk; based on the oscillation mode discrimination result, when it is judged that there is no oscillation risk under the current working condition, continue to monitor the power flow of each node in the new energy grid-connected system in real time; When it is determined that there is an oscillation risk, an emergency controller is added to the control loop of the new energy equipment at the best controllable and observable node.

10. A storage medium, characterized in that: It includes a stored program, which, when running, controls the device where the storage medium is located to execute the new energy station oscillation precise tracing and emergency control method as described in any one of claims 1 to 9.

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