A coordinated control method and system for improving the stability of broadband oscillations in power grids

Abstract

A coordinated control method and system for improving the stability of broadband oscillations in power grids utilizes a coordinated combination of local substation control at the plant end and regional master station control at the dispatch end to improve the stability of broadband oscillations in power grids. Local substations collect information, analyze broadband oscillation characteristics, upload data, generate local control strategies, and implement these strategies. Regional master stations access characteristic data uploaded by multiple local substations and perform global monitoring, analysis, and display, forming regional control strategies that are then distributed to each local substation for execution. Local substations receive the regional master station strategy and optimize it in combination with the local control strategy to form a final stabilization strategy. Furthermore, local substations autonomously execute local control strategies when regional control fails. This invention constructs a broadband oscillation defense control system at different temporal and spatial scales to achieve multi-dimensional linkage to quell regional and local broadband oscillations.

Description

Technical Field

[0001] The present invention belongs to the technical field of power grid stability control, and relates to a coordinated control method and system for improving the broadband oscillation stability of a power grid. Background Art

[0002] my country is experiencing rapid development in renewable energy generation technologies, such as wind and photovoltaic power, and the proportion of installed renewable energy capacity is increasing. Wind and solar resources are primarily concentrated in western my country. This inverse distribution of resources and loads dictates that large-scale centralized development and long-distance transmission are the dominant forms of large-scale renewable energy development and utilization in my country. High-voltage direct current (HVDC) and flexible alternating current (FACT) transmission have become the primary transmission methods for regional interconnection. With the grid connection of numerous renewable energy units and the integration of high-power power electronic equipment, the power system is characterized by a high proportion of power electronics.

[0003] While the high proportion of power electronics in power systems brings controllability and flexibility to grid operations, it also presents unprecedented challenges to the grid's dynamic security, stability, and control. When wind power, photovoltaic power, and DC transmission lines reach a certain scale in a power system, interactions between power electronic converters and between them and the grid can induce broadband oscillations ranging from a few hertz to several kilohertz. For example, clusters of direct-drive wind turbines experience sub- and super-synchronous oscillations when connected to weak AC grids. Offshore wind power, through flexible direct current (FDC) grid integration, and FDC transmission projects can also experience medium- and high-frequency oscillations ranging from several hundred to several kilohertz.

[0004] Broadband oscillations caused by grid-connected power electronic equipment can cause serious consequences, including equipment damage, large-scale wind turbine disconnections, and system outages. These threats threaten the safety of power grid equipment, the stability of the system, and the quality of electricity consumption. They also hinder the efficient integration of renewable energy sources like wind and solar power, threatening the safe and stable operation of the power system. Therefore, real-time monitoring and online early warning of broadband oscillations in power systems, along with effective control and control, are crucial for regional protection against broadband oscillations.

[0005] The current broadband oscillation regional master station focuses on the monitoring and early warning functions of broadband oscillations. By connecting to multiple broadband oscillation monitoring devices, it can realize the display and risk assessment of broadband oscillations in the regional power grid. Summary of the Invention

[0006] In order to address the deficiencies in the prior art, the present invention provides a coordinated control method and system for improving the stability of broadband oscillations in power grids. A multi-dimensional linkage broadband oscillation defense control system based on time-driven and space-driven is established through regional master stations and local devices. In terms of control, the regional master station integrates the power grid architecture and monitoring information to implement stability judgment within the region, generates and issues control strategies from a global perspective for local execution, and simultaneously arranges layered protection strategies in local substations to analyze and calculate access interval oscillations in real time, thereby achieving accurate, orderly, and optimal removal of disturbance sources. The method is suitable for the coordinated control of the stability of broadband oscillations in power grids caused by the grid connection of high-proportion and large-capacity new energy and the access of power electronic equipment.

[0007] In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0008] A coordinated control method for improving the stability of broadband oscillations in a power grid, the coordinated control method comprising the following steps:

[0009] Step 1: The local substation collects the three-phase voltage and three-phase current signals of the connected line to obtain the voltage and current sampling sequence;

[0010] Step 2: The regional master station communicates with multiple local substations within the area under its jurisdiction;

[0011] Step 3: The local substation performs real-time calculations on the voltage and current sampling sequences to obtain a set of broadband oscillation characteristic data, and sends the time-stamped oscillation characteristic data to the regional master station.

[0012] Step 4: The regional master station aligns the oscillation characteristic data sent by the local substations using a time scale. It then performs line oscillation analysis based on the topology of the regional power grid lines, the load levels of the lines, and the broadband oscillation characteristics of each line. It then generates a regional-level generator-shedding line set and sends it to the local substations.

[0013] Step 5: The local substation implements a localized broadband oscillation control strategy based on the local real-time identified oscillation pattern to form a localized power-off line set that is conducive to local stability.

[0014] Step 6: After receiving the regional-level power-off line set from the regional master station, the local substation summarizes and analyzes it with the local power-off line set decided locally. With regional stability as the priority, it selects and removes power-off lines for this round. If the regional master station fails to control the line, the local substation autonomously executes the local control strategy to quell local broadband oscillations.

[0015] Step 7: After the line is removed, wait for a while to determine whether the area is stable. If not, repeat steps 3 to 6 until the area is stable or all oscillating lines are removed.

[0016] The present invention further includes the following preferred embodiments:

[0017] Preferably, the broadband oscillation monitoring and control local substation is deployed at a new energy plant or wind power collection station or substation;

[0018] The broadband oscillation monitoring and control regional master station is deployed in the hub substation or regional dispatching center.

[0019] Preferably, in step 2, the regional master station communicates with multiple local substations within the area under its jurisdiction in real time through the dispatching data network, obtains the electrical quantity data sent by the local substations through the monitoring channel, and sends the power-off instruction to the local substations through the control channel. The monitoring channel and the control channel are independent of each other.

[0020] Preferably, in step 3, the broadband oscillation characteristic quantity data set includes: low-frequency oscillation power, sub- / super-synchronous oscillation power, broadband oscillation power; sub- / super-synchronous oscillation voltage / current, broadband oscillation voltage / current; sub- / super-synchronous oscillation positive-sequence impedance, broadband oscillation positive-sequence impedance, and the specific calculation process is:

[0021] Calculate the three-phase instantaneous power sequence using the voltage and current sampling sequence;

[0022] Perform fast Fourier transform on the voltage and current sampling sequence and the three-phase instantaneous power sequence;

[0023] The oscillation extreme points in the low-frequency, sub- / super-synchronous, and broadband frequency bands are found through the spectrum line extreme value discrimination method, and the corresponding oscillation characteristic quantities are obtained through the interpolation algorithm in the frequency domain, including the oscillating voltage phasor, oscillating current phasor, oscillating power phasor, and positive-sequence impedance phasor.

[0024] Preferably, step 4 specifically includes the following steps:

[0025] Step 41: The regional master station synchronizes the oscillation characteristic data sent by the w local substations according to the time stamp, and stores them in the real-time database at the corresponding time stamp position, obtaining broadband oscillation characteristic information for all lines in the region at each time section.

[0026] Step 42: The oscillation power amplitude P of the tie lines of v substations in the area i (j) Compare with the threshold TH, if P is satisfied i (j)≥TH, it means that the oscillation power amplitude of this tie line exceeds the limit, and the amplitude exceeding limit time counter accumulates. When the accumulated time reaches the fixed value T1, the amplitude exceeding limit action flag of this tie line is set to 1;

[0027] Step 43: According to the tie line oscillation power amplitude P i (j) The changing trend of the tie line is used to determine whether the oscillation of the tie line is diverging and set the divergence action flag of the tie line;

[0028] Step 44: allocating tie line oscillation weights according to the tie line oscillation determination results of steps 42 and 43;

[0029] Step 45: If the tie line meets the amplitude over-limit condition of step 42 or the divergent action condition of step 43, u power lines electrically connected to the tie line are formed into a power line cutting set arranged in the cutting order, taking into account the negative impedance degree of the line, the real-time power, and the grid connection strength factor.

[0030] Step 46: traverse all tie lines to form a power line cutter set of all oscillating tie lines, that is, a power line cutter optimal set within the station;

[0031] Step 47: Based on the optimal power line cutting set within the station and the tie line oscillation weight, the optimal power line cutting set within the region is obtained, and the regional-level power line sequential cutting combination is obtained by screening, i.e., the regional-level cutting line set.

[0032] Step 48: Send the regional level power-off line set to the local substation to execute the power-off command.

[0033] Preferably, in step 45, the order of cutting the power supply is arranged from large to small according to the magnitude of the cutting optimization factor Cu, and the cutting optimization factor Cu of the rth power supply line is r is calculated as follows:

[0034]

[0035] m represents the number of factors affecting generator tripping, which include the degree of line negative impedance, real-time power, and grid connection strength factor;

[0036] S i represents the equivalent value of the influencing factor of the i-th cutting machine;

[0037] Q i Represents the allocation weight of the i-th cutting factor.

[0038] Preferably, step 5 specifically includes the following steps:

[0039] Step 51: The local substation divides the access line into a power line group and a tie line group according to whether the access line is a wind farm collection line or a booster station outgoing line, and sets corresponding oscillation amplitude conditions for each group.

[0040] Step 52: Determine whether the power-off time has been reached based on the amplitude condition and duration of the oscillation circuit;

[0041] Step 53: When the power-off time is reached, a local power-off line set is formed based on the sorting results of the line negative impedance values ​​and active power values ​​at the current moment;

[0042] Step 54: Based on the limit on the number of disconnected lines or the power loss due to disconnection, a final set of local disconnected lines is screened and obtained.

[0043] Preferably, in step 6, after receiving the regional-level power-off line set issued by the regional master station, the local substation summarizes and analyzes the local power-off line set decided locally, with the goal of prioritizing regional stability. The specific implementation process of selecting and removing power-off lines in this round is as follows:

[0044] (1) The local substation and the regional master station detect whether the communication link is interrupted in real time based on the established real-time heartbeat signal;

[0045] (2) When the communication link between the master and substations is intact, the regional master station sends a regional-level cutting line set cutting control signal to the local substation after a delay of T1. The local substation generates a local cutting signal for the local cutting line set after a delay of T2, and T1≤T2 is satisfied.

[0046] (3) After receiving the power-off command from the regional master station, the local substation executes the power-off command from the regional master station and selects and cuts the power-off line for this round if the local power-off restriction conditions are met. The local substation also clears the local time counter and starts counting again.

[0047] Preferably, in step 6, if the regional master station fails to control, the local substation autonomously executes the local control strategy to quell the local broadband oscillation. The specific process is as follows:

[0048] (1) The local substation determines whether the connection is lost by checking the continuity of the real-time heartbeat signal with the regional master station;

[0049] (2) If the regional master station loses connection, the regional master station control fails, and the local substation executes the local power-off strategy after the set time T2 is reached according to the accumulation of its own time counter;

[0050] (3) After the communication link between the regional master station and the local substation is restored, the time counters of the local substation and the regional master station are reset and restarted.

[0051] A coordinated control system for implementing the coordinated control method for improving the broadband oscillation stability of a power grid, the coordinated control system comprising:

[0052] The electrical quantity data acquisition module is used to collect the three-phase voltage and three-phase current signals of the connected line at the local substation to obtain the voltage and current sampling sequence;

[0053] Communication module, used for regional master station to communicate with multiple local substations within the area under its jurisdiction;

[0054] The oscillation characteristic quantity data acquisition and upload module is used to perform real-time calculations on the voltage and current sampling sequences at the local substation to obtain a set of broadband oscillation characteristic quantity data, and upload the oscillation characteristic quantity data with time stamps to the regional master station;

[0055] The regional-level power-off line set generation and distribution module is used by the regional master station to align the oscillation characteristic data sent by the local substations through time scales. It then performs line oscillation analysis based on the topology of the power grid lines in the entire region, the load level of the lines, and the broadband oscillation characteristics of each line. It then generates a regional-level power-off line set and distributes it to the local substations.

[0056] The local cutting line set generation module is used by the local substation to implement a localized broadband oscillation control strategy based on the local real-time identification of the oscillation mode, thereby forming a local cutting line set that is conducive to local stability.

[0057] The coordination control module is used to collect and analyze the regional-level power-off line set received by the local substation from the regional master station, and then select and remove the power-off line set determined locally. This prioritizes regional stability and selects and removes the power-off lines for this round. If the regional master station fails, the local substation will autonomously execute the local control strategy to quell local broadband oscillations.

[0058] The iterative module is used to determine whether the area is stable after a delay after line removal. If it is unstable, the iterative module repeatedly runs the oscillation characteristic data acquisition and upload module, the regional-level line removal set generation and download module, the local line removal set generation module, and the coordination control module until the area is stable or all oscillating lines are removed.

[0059] The beneficial effects of the present invention are as follows:

[0060] To address the frequent broadband oscillations that occur in new power systems with large-scale renewable energy transmission and a high proportion of power electronic equipment connected to the grid, the present invention proposes a coordinated control method and system that improves the stability of broadband oscillations in the power grid by integrating local substation control at the power plant end with regional master station control at the dispatch end. The local substations collect information, analyze broadband oscillation characteristics, upload data, generate local control strategies, and implement these strategies. The regional master station accesses the characteristic data uploaded by multiple local substations for global monitoring, analysis, and display. It then combines the line network architecture, real-time power, and other factors to form a regional control strategy, which is then distributed to each local substation for execution. The local substations receive the regional master station strategy and optimize it in combination with the local control strategy to form a final stabilization strategy. Furthermore, when regional control fails, the local substations autonomously execute the local control strategy, achieving hierarchical, multi-dimensional, and mutually redundant broadband oscillation stability control for the power grid. By constructing a broadband oscillation defense control system with different temporal and spatial scales, the present invention forms a multi-dimensional linkage to quell regional and local broadband oscillations.

[0061] This invention achieves regional-level control through panoramic monitoring information from regional master stations and precise control through the in-station control functions of local substations. The regional master station and local substations work together to implement hierarchical protection control for broadband oscillations and multiple oscillation modes. This invention utilizes a broadband oscillation stabilization control method that coordinates regional and local control. This method eliminates oscillating lines within a region in a graded and gradual manner, quelling broadband oscillations with minimal generator disconnection. This prevents the impact of a large number of generators going offline on system stability and the adverse effects of frequent generator disconnections on generators, protecting the safety of the power grid and equipment while also improving the efficient absorption of renewable energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is a flowchart of the coordinated control method of the present invention;

[0063] Figure 2 This is a flow chart of the coordinated control method of the present invention;

[0064] Figure 3 This is a schematic diagram of the network topology structure of a certain area in Example 1 of the present invention;

[0065] Figure 4 This is a schematic diagram of the logic execution of the local substation in Example 1 of the present invention;

[0066] Figure 5 This is a schematic diagram of the logic execution of the regional master station in Example 1 of the present invention. DETAILED DESCRIPTION

[0067] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without making creative efforts are all within the scope of protection of the present invention.

[0068] like Figure 1 As shown, the present invention provides a coordinated control method for improving the stability of broadband oscillations in power grids. Regional-level control is performed through panoramic monitoring information from regional master stations, and precise control is performed through the in-station control functions of local substations. The regional master station and local substations cooperate to perform hierarchical protection control of broadband oscillations in multiple oscillation modes. The problem of broadband oscillations that frequently occur in new "double-high" power systems is solved by coordinated control that quells regional oscillations with minimal power outages. In a preferred but non-limiting embodiment of the present invention, the steps include the following steps 1-7:

[0069] Step 1: Deploy a broadband oscillation monitoring and control substation at a renewable energy plant, wind power collection station, or substation. The substation collects the three-phase voltage and current signals of the connected line to obtain a voltage and current sampling sequence.

[0070] Step 2: Deploy a broadband oscillation monitoring and control regional master station at a hub substation or regional dispatching center to communicate with multiple local substations within the jurisdiction;

[0071] Further preferably, in step 2, the regional master station communicates with multiple local substations within the area under its jurisdiction in real time through the dispatching data network, obtains the electrical quantity data sent by the local substations through the monitoring channel, and sends the power-off instruction to the local substations through the control channel. The monitoring channel and the control channel are independent of each other.

[0072] Step 3: The local substation performs real-time calculations on the voltage and current sampling sequences to obtain a broadband oscillation characteristic quantity data set, and sends the oscillation characteristic quantity data with time stamps to the regional master station.

[0073] Further preferably, in step 3, the local substation obtains a multi-dimensional broadband oscillation characteristic quantity data set of each line by analyzing the sampling sequence of the three-phase voltage and three-phase current of the collected line;

[0074] The broadband oscillation characteristic quantity data set includes:

[0075] Low frequency oscillation power, sub / super synchronous oscillation power, broadband oscillation power;

[0076] Sub / supersynchronous oscillation voltage / current, broadband oscillation voltage / current;

[0077] Sub / super synchronous oscillation positive sequence impedance, broadband oscillation positive sequence impedance.

[0078] The specific calculation process is:

[0079] Using the voltage and current sampling sequence u ai (k),u bi (k),u ci (k) and i ai (k), i bi (k), i ci (k) (where i represents the i-th line and k represents the sampling sequence point), calculate the three-phase instantaneous power sequence p i (k);

[0080] For sequence u ai (k),u bi (k),u ci (k), i ai (k), i bi (k), i ci (k), pi (k) Perform weight processing and fast Fourier transform.

[0081] When implemented in an embedded device, in order to ensure the resolution of each frequency band and consider computational efficiency, coarse sampling processing is performed at different intervals according to the frequency band range.

[0082] The oscillation extreme points in each frequency band (low frequency, sub / super synchronous, broadband) are found by the spectrum line extreme value discrimination method, and the accurate oscillation characteristic quantity, i.e., the phasor, is obtained by the interpolation algorithm in the frequency domain. (j represents the jth frequency point, j=1,…,m).

[0083] Calculate the oscillating positive sequence voltage phasor based on the oscillating voltage phasor and the oscillating current phasor and positive sequence current phasor Further obtain the positive sequence impedance phasor

[0084] The calculation formulas for the positive sequence voltage phasor and the positive sequence current phasor are as follows:

[0085]

[0086]

[0087]

[0088] The calculation formula of the positive sequence impedance phasor is as follows:

[0089]

[0090] calculate The real part of the positive sequence resistance characteristic is obtained,

[0091] The local substation packages the broadband oscillation characteristic quantity data obtained by the above real-time calculation, marks it with a synchronization time stamp, and sends it to the regional master station through the monitoring channel of the dispatching data network.

[0092] Step 4: The regional master station aligns the oscillation characteristic data sent by the local substations through time calibration, and performs line oscillation analysis based on the topology of the power grid lines in the entire region, the load level of the lines, and the broadband oscillation characteristic information of each line. It generates a regional-level generator-cutting line set and sends it to the local substations.

[0093] Further preferably, in the above step 4, the regional master station determines regional stability based on the oscillation characteristic data sent by the local substation, and forms a regional control shutdown quantity set. The specific process of regional control implementation is as follows:

[0094] Step 41: The regional master station synchronizes the oscillation characteristic data sent by the w local substations according to the time stamp, and stores them in the real-time database at the corresponding time stamp position, obtaining broadband oscillation characteristic information for all lines in the region at each time section.

[0095] Step 42: The oscillation power amplitude P of the tie lines of v substations in the area i (j) Compare with the threshold TH, if P is satisfied i (j)≥TH, it means that the oscillation power amplitude of this tie line exceeds the limit, and the amplitude exceeding limit time counter accumulates. When the accumulated time reaches the fixed value T1, the amplitude exceeding limit action flag of this tie line is set to 1;

[0096] Step 43: According to the tie line oscillation power amplitude P i (j) The changing trend of the tie line is used to determine whether the oscillation of the tie line is diverging and set the divergence action flag of the tie line;

[0097] Step 44: allocating tie line oscillation weights according to the tie line oscillation determination results of steps 42 and 43;

[0098] Step 45: If the tie line meets the amplitude over-limit condition of step 42 or the divergent action condition of step 43, u power lines electrically connected to the tie line are formed into a power line cutting set arranged in the cutting order, taking into account the negative impedance degree of the line, the real-time power, and the grid connection strength factor.

[0099] The order of power line cutting is arranged from large to small according to the magnitude of the power line cutting optimization factor Cu. The power line cutting optimization factor Cu of the rth power line is calculated as follows:

[0100]

[0101] m represents the number of factors affecting generator tripping, which include the degree of line negative impedance, real-time power, and grid connection strength factor.

[0102] S i Represents the equivalent value of the factor influencing the i-th generator tripping. For the negative line impedance, S is equivalent to the absolute value of the negative resistance relative to the rated resistance (per unit). For positive resistance, this value is infinite, and the contribution to the optimal value of the corresponding generator tripping is zero. For real-time power, S is equivalent to the per-unit value of the real-time power relative to the rated power. For the grid connection strength factor, S is equivalent to the number of connected nodes.

[0103] Q i Represents the allocation weight of the i-th cutting factor.

[0104] Step 46: traverse all tie lines to form a power line cutter set of all oscillating tie lines, that is, a power line cutter optimal set within the station;

[0105] Step 47: The optimal power line cutting set in the local station is combined with the tie line oscillation weight to obtain the optimal power line cutting set in the region, and the regional level power line sequential cutting combination is obtained by screening, that is, the regional level cutting line set.

[0106] Step 48: Send the regional level power-off line set to the local substation to execute the power-off command.

[0107] Step 5: The local substation implements a localized broadband oscillation control strategy based on the local real-time identified oscillation mode to form a local switching line set that is conducive to local stability.

[0108] Further preferably, in the above step 5, the local substation forms a local control strategy based on the identification of the real-time oscillation mode, and the specific implementation process is:

[0109] Step 51: The local substation divides the access line into a power line group and a tie line group according to whether the access line is a wind farm collection line or a booster station outgoing line, and sets corresponding oscillation amplitude conditions for each group.

[0110] Step 52: Determine whether the power-off time has been reached based on the amplitude condition and duration of the oscillation circuit;

[0111] Step 53: When the power-off time is reached, a local power-off line set is formed based on the sorting results of the line negative impedance values ​​and active power values ​​at the current moment;

[0112] Step 54: Based on the limit on the number of disconnected lines or the power loss due to disconnection, a final set of local disconnected lines is screened and obtained.

[0113] Step 6: After receiving the regional-level power-off line set from the regional master station, the local substation summarizes and analyzes it with the local power-off line set decided locally. With the goal of prioritizing regional stability, it selects and removes power-off lines for this round. If the regional master station fails to control, the local substation autonomously executes the local control strategy to quell local broadband oscillations.

[0114] Further preferably, in step 6 above, after receiving the regional-level power-off line set sent by the regional master station, the local substation summarizes and analyzes the set of local power-off lines decided locally, with the goal of prioritizing regional stability. The specific implementation process of selecting and removing power-off lines in this round is as follows:

[0115] (1) The local substation and the regional master station detect whether the communication link is interrupted in real time based on the established real-time heartbeat signal;

[0116] (2) When the communication link between the master and substations is intact, the regional master station sends a regional-level cutting line set cutting control signal to the local substation after a delay of T1. The local substation generates a local cutting signal for the local cutting line set after a delay of T2, and T1≤T2 is satisfied.

[0117] (3) After receiving the power-off command from the regional master station, the local substation executes the power-off command from the regional master station and selects and cuts the power-off line for this round if the local power-off restriction conditions are met. The local substation also clears the local time counter and starts counting again.

[0118] In step 6 above, if the regional master station fails to control, the local substation will autonomously implement the local control strategy to quell the local broadband oscillation. The specific process is as follows:

[0119] (1) The local substation determines whether it is disconnected by checking the continuity of the real-time heartbeat signal with the regional master station;

[0120] (2) If the regional master station loses connection, the regional master station control fails, and the local substation accumulates its own time counter and executes the local power-off strategy after reaching the set time T2;

[0121] (3) After the communication link between the regional master station and the local substation is restored, the time counters of the local substation and the regional master station are reset and restarted.

[0122] Step 7: After the line is removed, wait for a while to determine whether the area is stable. If not, repeat steps 3 to 6 until the area is stable or all oscillating lines are removed.

[0123] Example 1

[0124] The present invention discloses a coordinated control method implementation process for improving the broadband oscillation stability of a power grid. First, the local side substation collects the three-phase voltage and three-phase current of the connected line and calculates the instantaneous power. Then, the three-phase phase voltage, phase current phasor and oscillation power within a wide frequency range are obtained through fast Fourier transform calculation. The positive sequence impedance phasor is calculated based on the three-phase phase voltage phasor and the three-phase phase current phasor. The phase voltage phasor, phase current phasor, positive sequence impedance phasor and oscillation power form a local oscillation characteristic quantity set, and the time scales are aligned and then sent to the regional master station. At the same time, the local substation forms a local control strategy based on the local oscillation characteristic quantity set. The regional master station forms a minimum power-off quantity set to maintain regional stability based on the information sent by all substations, combined with the grid structure of the entire region and the line flow conditions, and sends it to each local substation. Each local substation receives the regional control strategy, and combines and optimizes it with the local control strategy to form a local final control strategy export.

[0125] like Figure 1-2As shown, a coordinated control method for improving the broadband oscillation stability of a power grid provided by embodiment 1 of the present invention specifically adopts the following steps 1-7:

[0126] Step 1: Further preferably, a broadband oscillation monitoring and control local substation is deployed at a new energy plant, wind power collection station, or transformer substation, and the local substation uses a sampling frequency f samp Collect the three-phase voltage and three-phase current of all connected lines, and stipulate that the direction of outflow from the AC bus is the positive direction. The corresponding voltage and current sampling sequences are u ai (k),u bi (k),u ci (k) and i ai (k), i bi (k), i ci (k), where i represents the i-th line and k represents the sampling sequence point.

[0127] In this embodiment, Figure 3 The broadband oscillation monitoring and control system is deployed in the regional power grid shown in the figure. Broadband oscillation monitoring and control local substations 1-4 are deployed in three 220kV switch stations and a 500kV booster station respectively:

[0128] On-site substation 1 is connected to four lines: three wind farm incoming lines and one interconnecting line between switch stations, marked as S1-L1, S1-L2, S1-L3, and S1-L4. The rated current of the four lines is 1000A.

[0129] On-site substation 2 is connected to four lines: three wind farm incoming lines and one interconnecting line between switch stations, marked as S2-L1, S2-L2, S2-L3, and S2-L4. The rated current of the four lines is 1000A.

[0130] On-site substation 3 is connected to seven lines, namely: 4 wind farm incoming lines and 3 switch station interconnection lines, marked as S3-L1, S3-L2, S3-L3, S3-L4, S3-L5, S3-L6, S3-L7. The rated current of the seven lines is 1000A.

[0131] The local substation 4 is connected to six lines, namely: 3 wind farm incoming lines, 1 interconnecting line between switch stations and 2 booster station outgoing lines, marked as S4-L1, S4-L2, S4-L3, S4-L4, S4-L5 and S4-L6. The rated current of the first four lines is 1000A, and the rated current of the last two lines is 1500A.

[0132] Each substation measures the three-phase voltage and three-phase current of the line it accesses in terms of f samp = Sampling is performed at a sampling frequency of 12800 Hz.

[0133] Step 2: Deploy a broadband oscillation monitoring and control master station at the 500kV booster station. This station communicates with the four local substations via the dispatching data network. The master station and the four substations are connected to the same timing source.

[0134] Step 3: The local substation calculates the broadband oscillation characteristic quantity for the access line.

[0135] The specific calculation process is:

[0136] Using the voltage and current sampling sequence u ai (k),u bi (k),u ci (k) and i ai (k), i bi (k), i ci (k) Calculate the three-phase instantaneous power sequence p i (k);

[0137] For sequence u ai (k),u bi (k),u ci (k), i ai (k), i bi (k), i ci (k), p i (k) Perform a fast Fourier transform (FFT).

[0138] The calculation range of broadband oscillation frequency is 0.1Hz~2500Hz, which is divided into low frequency band 0.1Hz~2.5Hz, sub / super synchronous frequency band 2.5Hz~95Hz, and broadband band 100Hz~2500Hz.

[0139] The low frequency band and sub-supersynchronous frequency band are coarsely sampled, the sampling frequencies are reduced to 128Hz and 1280Hz respectively, and the number of FFT analysis points is 1024;

[0140] For wide frequency bands, the number of FFT analysis points is 2048.

[0141] The data windowing function is a Hamming window, and the spectrum line extreme value discrimination method is used to find the oscillation extreme points of each frequency band. Then, the double-peak spectrum line interpolation algorithm is used to correct the data of the oscillation characteristic points.

[0142] The calculation cycle of the full-band characteristic quantities of all lines is 100ms. After the calculation is completed, it is sent to the regional master station together with the current time stamp.

[0143] The main oscillation modes of the multi-dimensional oscillation characteristics of the monitoring lines of each substation are shown in Table 1 below.

[0144] Table 1 List of all line oscillation characteristics

[0145]

[0146]

[0147]

[0148]

[0149] The positive sequence impedance calculated for each substation is listed in Table 2. For the inter-station tie lines, the sequence impedance is not considered.

[0150] Table 2 List of positive sequence impedances of all power lines

[0151]

[0152]

[0153] Step 4: The regional master station determines the regional stability based on the oscillation of the wind farm incoming lines, inter-station interconnection lines, and outgoing lines of the substations within its jurisdiction, and forms a regional control curtailment volume set for the incoming power lines.

[0154] In this embodiment, the regional master station uses the oscillation power of S1-L4, S2-L4, S3-L7, S4-L5, and S4-L6 (collectively referred to as tie lines) to determine regional stability.

[0155] The amplitudes of the sub- / super-synchronous oscillation power and the broadband oscillation power are compared with a judgment threshold TH, which is 3% of the line rated power. If the oscillation power exceeds the judgment threshold, it is considered that a disturbance has occurred.

[0156] The rated power of S1-L4, S2-L4, and S3-L7 is 381MW, and the judgment threshold is 11MW;

[0157] The rated power of S4-L5 and S4-L6 is 1299MW, and the judgment threshold is 39MW.

[0158] According to the numerical conditions in Table 1, all tie lines have disturbances exceeding the threshold.

[0159] The oscillation trend of the tie line is determined by judging whether the tie line is divergent based on the oscillation power amplitude of the continuous time section. In this embodiment, the oscillations of the lines S1-L4 and S3-L7 show a divergent trend.

[0160] The distribution weights of the tie line oscillation exceeding the threshold and the divergent oscillation are respectively Therefore, the oscillation severity set of each tie line is {{S1-L4, 1}, {S3-L7, 1},

[0161] For the interconnecting line S1-L4, the power lines electrically connected to it are S1-L1, S1-L2, and S1-L3 respectively.

[0162] According to Table 2, S1-L1 is a positive resistor, and the negative resistance values ​​of S1-L2 and S1-L3 are 80Ω and 120Ω respectively;

[0163] The real-time power is 200MW, 250MW and 160MW respectively;

[0164] They all have only electrical connections to the switch station, and the number of grid connection nodes is 1.

[0165] The weights of the factors affecting the degree of line negative resistance are: The weights of real-time power influencing factors are: The weights of the factors influencing the grid connection strength factor are:

[0166] Based on this, the optimal factor for cutting off the power line S1-L1 is:

[0167]

[0168] Similarly, the power line S1-L2 and S1-L3 switching priority factors are:

[0169]

[0170]

[0171] Similarly, the optimal factors for cutting off the power lines associated with the tie line S2-L4 are Cu S2-L1 =1.38,Cu S2-L2 =1.43,Cu S2-L3 =1.36;

[0172] The optimal factors for power line disconnection associated with tie line S3-L7 are Cu S3-L1 =1.35,Cu S3-L2 =1.21,Cu S3-L3 =1.28,Cu S3-L4 =1.52;

[0173] The optimal factors for power lines associated with tie lines S4-L5 and S4-L6 are Cu S4-L1 =1.43,Cu S4-L2 =1.47,Cu S4-L3 =1.39,Cu S4-L4 =1.28.

[0174] For substation 1, the tie line oscillation severity set is {S1-L4, 1}, and the power line cut-off optimization set in this station is {Cu S1-L1 =1.41,Cu S1-L2 =1.45,Cu S1-L3 =1.44}; Considering the serious oscillation of the tie line, the optimal set of power line cut-offs in the region is {Cu S1-L1 =1.41,Cu S1-L2 =1.45,Cu S1-L3 =1.44}.

[0175] For substation 2, the tie line oscillation severity set is The preferred set of power cord cutting machines in this site is {Cu S2-L1 =1.38,Cu S2-L2 =1.43,Cu S2-L3 =1.36}; Considering the serious oscillation of the tie line, the optimal set of power line cut-offs in the region is {Cu S2-L1 =0.69, Cu S2-L2 =0.715, Cu S2-L3 =0.68}.

[0176] For substation 3, the tie line oscillation severity set is {S3-L7, 1}, and the power line internal cutting machine optimization set is {Cu S3-L1 =1.35,Cu S3-L2 =1.21,Cu S3-L3 =1.28,Cu S3-L4 =1.52}; Considering the serious oscillation of the tie line, the optimal set of power line cut-offs in the region is {Cu S3-L1 =1.35,Cu S3-L2 =1.21,Cu S3-L3 =1.28,Cu S3-L4 =1.52}.

[0177] For substation 4, the tie line oscillation severity set is The preferred set of power cord cutting machines in this site is {Cu S4-L1 =1.43,Cu S4-L2 =1.47,Cu S4-L3 =1.39,Cu S4-L4 =1.28}; Considering the serious oscillation of the tie line, the optimal set of power line cut-offs in the region is: {Cu S4-L1 =0.715, Cu S4-L2 =0.735, Cu S4-L3 =0.695,Cu S4-L4 =0.64}.

[0178] Assuming that the number of wind farm power lines cut off in a round in the region does not exceed 3, for this round of oscillation, the set of power lines cut off in the region, that is, the set of regional-level power lines cut off is {Cu S3-L4 |1.52, Cu S1-L2 |1.45, Cu S1-L3 |1.44} and sent to the local side substation.

[0179] Step 5: The local substation forms a local control strategy based on the oscillation mode identified in real time.

[0180] In this embodiment, the local substation 1 is taken as an example for description, the power line groups are S1-L1, S1-L2, S1-L3, and the tie line group is S1-L4.

[0181] Whether oscillation occurs is determined based on the current or power oscillation amplitude of the power line and the tie line. For the power line, the oscillation threshold is designed to be 1% of the rated value, and for the tie line, the oscillation threshold is designed to be 3% of the rated value.

[0182] Therefore, the oscillation current threshold and oscillation power threshold of the power line are set to 100A and 3.8MW respectively, and the oscillation threshold of the tie line is set to 300A and 11MW.

[0183] According to Table 1, the current amplitude of line S1-L1 exceeds the set threshold, the power amplitude of line S1-L2 exceeds the set threshold, the current amplitude and power amplitude of line S1-L3 both exceed the set threshold, and the power amplitude of line S1-L4 exceeds the set threshold. The real-time active power values ​​of lines S1-L1, S1-L2, and S1-L3 are 200MW, 250MW, and 160MW, respectively.

[0184] According to Table 2, line S1-L1 has positive impedance, and line S1-L2 has a lower negative impedance than line S1-L3. Therefore, based on the negative impedance ranking, the order of removal is S1-L2, then S1-L3. After removing the negative impedance lines, the order of removal is S1-L1, sorted from low to high by real-time power value.

[0185] The local switching line set of the local substation is limited by the power loss value within the station. In this embodiment, the power loss threshold is set to 450MW. Therefore, during this oscillation, the local switching line set of local substation 1 is {S1-L2, S1-L3}.

[0186] Using the same calculation idea, the local cutting line set of local substation 2 is {S2-L1, S2-L2}, the local cutting line set of local substation 3 is {S3-L4, S3-L1}, and the local cutting line set of local substation 4 is {S4-L2, S4-L1, S4-L3}.

[0187] Steps 6-7: The local substation and the regional master station determine the interruption of the communication link through the ten-millisecond heartbeat signal. If the communication link is intact, the local substation implements the regional master station's power-off strategy, and the local time accumulation counter is cleared and does not accumulate.

[0188] For example, in the above embodiment, the regional-level power-off line set received by substation 1 is Line 2 and Line 3. Compared with the local power-off constraint of "power loss less than 450MW", it can be met. Therefore, Line 2 and Line 3 of this station are disconnected.

[0189] Similarly, the regional-level disconnection line set received by substation 3 is line 4, and it meets the local disconnection restriction conditions of substation 3, so line 4 of this station is disconnected;

[0190] For substations 2 and 4, the regional master station does not send down the regional-level disconnection line set, so the lines are not disconnected.

[0191] If the communication link is interrupted, the local switching strategy is implemented. For example, if the communication between local substation 2 and the regional master station is interrupted, lines 1 and 2 of the local switching line set decided by this station are cut off.

[0192] When the communication link is intact, the regional master station generates a regional control strategy (i.e., the cutting control signal of the regional-level cutting line set) after time T1 and sends it to the local substation. If the communication link is interrupted, the regional time accumulation counter is reset to zero and does not accumulate.

[0193] The local policy time setting value T2 is higher than the regional policy time setting value T1. In this embodiment, T1 = 2 seconds and T2 = 3 seconds.

[0194] The control logic of the regional master station and the local substation cooperates. The logic execution diagram of the local substation is as follows Figure 4 As shown, the logic execution diagram of the regional master station is as follows Figure 5 shown.

[0195] A coordinated control system for implementing the coordinated control method for improving the broadband oscillation stability of a power grid is characterized by:

[0196] The coordinated control system includes:

[0197] The electrical quantity data acquisition module is used to collect the three-phase voltage and three-phase current signals of the connected line at the local substation to obtain the voltage and current sampling sequence;

[0198] Communication module, used for regional master station to communicate with multiple local substations within the area under its jurisdiction;

[0199] The oscillation characteristic quantity data acquisition and upload module is used to perform real-time calculations on the voltage and current sampling sequences at the local substation to obtain a set of broadband oscillation characteristic quantity data, and upload the oscillation characteristic quantity data with time stamps to the regional master station;

[0200] The regional-level power-off line set generation and distribution module is used by the regional master station to align the oscillation characteristic data sent by the local substations through time scales. It then performs line oscillation analysis based on the topology of the power grid lines in the entire region, the load level of the lines, and the broadband oscillation characteristics of each line. It then generates a regional-level power-off line set and distributes it to the local substations.

[0201] The local cutting line set generation module is used by the local substation to implement a localized broadband oscillation control strategy based on the local real-time identification of the oscillation mode, thereby forming a local cutting line set that is conducive to local stability.

[0202] The coordination control module is used to collect and analyze the regional-level power-off line set received by the local substation from the regional master station, and then select and remove the power-off line set determined locally. This prioritizes regional stability and selects and removes the power-off lines for this round. If the regional master station fails, the local substation will autonomously execute the local control strategy to quell local broadband oscillations.

[0203] The iterative module is used to determine whether the area is stable after a delay after line removal. If it is unstable, the iterative module repeatedly runs the oscillation characteristic data acquisition and upload module, the regional-level line removal set generation and download module, the local line removal set generation module, and the coordination control module until the area is stable or all oscillating lines are removed.

[0204] The beneficial effects of the present invention are as follows:

[0205] To address the frequent broadband oscillations that occur in new power systems with large-scale renewable energy transmission and a high proportion of power electronic equipment connected to the grid, the present invention proposes a coordinated control method and system that improves the stability of broadband oscillations in the power grid by integrating local substation control at the power plant end with regional master station control at the dispatch end. The local substations collect information, analyze broadband oscillation characteristics, upload data, generate local control strategies, and implement these strategies. The regional master station accesses the characteristic data uploaded by multiple local substations for global monitoring, analysis, and display. It then combines the line network architecture, real-time power, and other factors to form a regional control strategy, which is then distributed to each local substation for execution. The local substations receive the regional master station strategy and optimize it in combination with the local control strategy to form a final stabilization strategy. Furthermore, when regional control fails, the local substations autonomously execute the local control strategy, achieving hierarchical, multi-dimensional, and mutually redundant broadband oscillation stability control for the power grid. By constructing a broadband oscillation defense control system with different temporal and spatial scales, the present invention forms a multi-dimensional linkage to quell regional and local broadband oscillations.

[0206] This invention achieves regional-level control through panoramic monitoring information from regional master stations and precise control through the in-station control functions of local substations. The regional master station and local substations work together to implement hierarchical protection control for broadband oscillations and multiple oscillation modes. This invention utilizes a broadband oscillation stabilization control method that coordinates regional and local control. This method eliminates oscillating lines within a region in a graded and gradual manner, quelling broadband oscillations with minimal generator disconnection. This prevents the impact of a large number of generators going offline on system stability and the adverse effects of frequent generator disconnections on generators, protecting the safety of the power grid and equipment while also improving the efficient absorption of renewable energy.

[0207] The present disclosure may be a system, method and / or computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0208] A computer-readable storage medium can be a tangible device that can hold and store instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination thereof. As used herein, a computer-readable storage medium is not to be construed as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through an electrical wire.

[0209] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions to be stored in the computer-readable storage medium in each computing / processing device.

[0210] The computer program instructions for performing the operations of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, and conventional procedural programming languages ​​such as "C" language or similar programming languages. Computer-readable program instructions may be executed entirely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., utilizing an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be personalized by utilizing the state information of the computer-readable program instructions. The electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0211] Various aspects of the present disclosure are described herein with reference to flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present disclosure. It should be understood that each block of the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer-readable program instructions.

[0212] These computer-readable program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, thereby producing a machine, so that when these instructions are executed by the processor of the computer or other programmable data processing device, a device is generated that implements the functions / actions specified in one or more blocks in the flowchart and / or block diagram. These computer-readable program instructions can also be stored in a computer-readable storage medium, where these instructions cause the computer, programmable data processing device, and / or other device to operate in a specific manner. Thus, the computer-readable medium storing the instructions comprises an article of manufacture that includes instructions for implementing various aspects of the functions / actions specified in one or more blocks in the flowchart and / or block diagram.

[0213] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device so that a series of operational steps are performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby causing the instructions executed on the computer, other programmable data processing apparatus, or other device to implement the functions / actions specified in one or more blocks in the flowchart and / or block diagram.

[0214] The flow charts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the systems, methods and computer program products according to multiple embodiments of the present disclosure. In this regard, each box in the flow chart or block diagram can represent a part of a module, program segment or instruction, and the part of the module, program segment or instruction contains one or more executable instructions for realizing the prescribed logical function. In some alternative implementations, the functions marked in the box can also occur in a sequence different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flow chart, and the combination of the boxes in the block diagram and / or flow chart can be implemented by a dedicated hardware-based system that performs the prescribed function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0215] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A coordinated control method for improving the stability of broadband oscillations in a power grid, characterized by: The coordinated control method comprises the following steps: Step 1: The local substation collects the three-phase voltage and three-phase current signals of the connected line to obtain the voltage and current sampling sequence; Step 2: The regional master station communicates with multiple local substations within the area under its jurisdiction; Step 3: The local substation performs real-time calculations on the voltage and current sampling sequences to obtain a set of broadband oscillation characteristic data, and sends the time-stamped oscillation characteristic data to the regional master station. Step 4: The regional master station aligns the oscillation characteristic data sent by the local substations using a time scale. It then performs line oscillation analysis based on the topology of the regional power grid lines, the load levels of the lines, and the broadband oscillation characteristics of each line. It then generates a regional-level generator-shedding line set and sends it to the local substations. Step 5: The local substation implements a localized broadband oscillation control strategy based on the local real-time identified oscillation pattern to form a localized power-off line set that is conducive to local stability. Step 6: After receiving the regional-level power-off line set from the regional master station, the local substation summarizes and analyzes it with the local power-off line set decided locally. With regional stability as the priority, it selects and removes power-off lines for this round. If the regional master station fails to control the line, the local substation autonomously executes the local control strategy to quell local broadband oscillations. Step 7: After the line is removed, wait for a while to determine whether the area is stable. If not, repeat steps 3 to 6 until the area is stable or all oscillating lines are removed.

2. A coordinated control method for improving the broadband oscillation stability of a power grid according to claim 1, characterized in that: Broadband oscillation monitoring and control substations are deployed in new energy plants, wind power collection stations, or substations; The broadband oscillation monitoring and control regional master station is deployed in the hub substation or regional dispatching center.

3. The coordinated control method for improving the broadband oscillation stability of a power grid according to claim 1, characterized in that: In step 2, the regional master station communicates with multiple local substations within its jurisdiction in real time through the dispatching data network, obtains the electrical quantity data sent by the local substations through the monitoring channel, and sends the generator tripping command to the local substations through the control channel. The monitoring channel and the control channel are independent of each other.

4. The coordinated control method for improving the broadband oscillation stability of a power grid according to claim 1, characterized in that: In step 3, the broadband oscillation characteristic quantity data set includes: low-frequency oscillation power, sub- / super-synchronous oscillation power, broadband oscillation power; sub- / super-synchronous oscillation voltage, sub- / super-synchronous oscillation current, broadband oscillation voltage, broadband oscillation current; sub- / super-synchronous oscillation positive-sequence impedance, broadband oscillation positive-sequence impedance. The specific calculation process is: Calculate the three-phase instantaneous power sequence using the voltage and current sampling sequence; Perform fast Fourier transform on the voltage and current sampling sequence and the three-phase instantaneous power sequence; The oscillation extreme points in the low-frequency, sub- / super-synchronous, and broadband frequency bands are found through the spectrum line extreme value discrimination method, and the corresponding oscillation characteristic quantities are obtained through the interpolation algorithm in the frequency domain, including the oscillating voltage phasor, oscillating current phasor, oscillating power phasor, and positive-sequence impedance phasor.

5. The coordinated control method for improving the broadband oscillation stability of a power grid according to claim 1, characterized in that: Step 4 specifically includes the following steps: Step 41: The regional master station synchronizes the oscillation characteristic data sent by the w local substations according to the time stamp, and stores them in the real-time database at the corresponding time stamp position, obtaining broadband oscillation characteristic information for all lines in the region at each time section. Step 42: The oscillation power amplitude P of the tie lines of v substations in the area i (j) Compare with the threshold TH, if P is satisfied i (j)≥TH, it means that the oscillation power amplitude of this tie line exceeds the limit, and the amplitude exceeding limit time counter accumulates. When the accumulated time reaches the fixed value T1, the amplitude exceeding limit action flag of this tie line is set to 1; Step 43: According to the tie line oscillation power amplitude P i (j) The changing trend of the tie line is used to determine whether the oscillation of the tie line is diverging and set the divergence action flag of the tie line; Step 44: allocating tie line oscillation weights according to the tie line oscillation determination results of steps 42 and 43; Step 45: If the tie line meets the amplitude over-limit condition of step 42 or the divergence action condition of step 43, u power lines electrically connected to the tie line are formed into a power line disconnection set arranged in a disconnection order, taking into account the negative impedance of the line, the real-time power, and the grid connection strength factor; Step 46: traverse all tie lines to form a power line cutter set of all oscillating tie lines, that is, a power line cutter optimal set within the station; Step 47: Based on the optimal power line cutting set within the station and the tie line oscillation weight, the optimal power line cutting set within the region is obtained. The regional-level power line sequential cutting combination is screened to obtain the regional-level cutting line set. Step 48: Send the regional level power-off line set to the local substation to execute the power-off command.

6. A coordinated control method for improving the broadband oscillation stability of a power grid according to claim 5, characterized in that: In step 45, the order of cutting the power supply is arranged from large to small according to the magnitude of the cutting optimization factor Cu. The cutting optimization factor Cu of the rth power supply line is r is calculated as follows: m represents the number of factors affecting generator tripping, which include the degree of line negative impedance, real-time power, and grid connection strength factor; S i represents the equivalent value of the influencing factor of the i-th cutting machine; Q i Represents the allocation weight of the i-th cutting factor.

7. The coordinated control method for improving the broadband oscillation stability of a power grid according to claim 1, characterized in that: Step 5 specifically includes the following steps: Step 51: The local substation divides the access line into a power line group and a tie line group according to whether the access line is a wind farm collection line or a booster station outgoing line, and sets corresponding oscillation amplitude conditions for each group. Step 52: Determine whether the power-off time has been reached based on the amplitude condition and duration of the oscillation circuit; Step 53: When the power-off time is reached, a local power-off line set is formed based on the sorting results of the line negative impedance values ​​and active power values ​​at the current moment; Step 54: Based on the limit on the number of disconnected lines or the power loss due to disconnection, a final set of local disconnected lines is screened and obtained.

8. The coordinated control method for improving the broadband oscillation stability of a power grid according to claim 1, characterized in that: In step 6, after receiving the regional-level power-off line set from the regional master station, the local substation summarizes and analyzes it with the local power-off line set decided locally. With the goal of prioritizing regional stability, the specific implementation process for selecting and removing power-off lines in this round is as follows: (1) The local substation and the regional master station detect whether the communication link is interrupted in real time based on the established real-time heartbeat signal; (2) When the communication link between the master and substations is intact, the regional master station sends a regional-level cutting line set cutting control signal to the local substation after a delay of T1. The local substation generates a local cutting signal for the local cutting line set after a delay of T2, and T1≤T2 is satisfied. (3) After receiving the power-off command from the regional master station, the local substation executes the power-off command from the regional master station and selects and cuts the power-off line for this round if the local power-off restriction conditions are met. The local substation also clears the local time counter and starts counting again.

9. The coordinated control method for improving the broadband oscillation stability of a power grid according to claim 1, characterized in that: In step 6, if the regional master station fails to control, the local substation will autonomously implement the local control strategy to quell the local broadband oscillation. The specific process is as follows: (1) The local substation determines whether the connection is lost by checking the continuity of the real-time heartbeat signal with the regional master station; (2) If the regional master station loses connection, the regional master station control fails, and the local substation executes the local power-off strategy after the set time T2 is reached according to the accumulation of its own time counter; (3) After the communication link between the regional master station and the local substation is restored, the time counters of the local substation and the regional master station are reset and restarted.

10. A coordinated control system for implementing the coordinated control method for improving the broadband oscillation stability of a power grid according to any one of claims 1 to 9, characterized in that: The coordinated control system includes: The electrical quantity data acquisition module is used to collect the three-phase voltage and three-phase current signals of the connected line at the local substation to obtain the voltage and current sampling sequence; Communication module, used for regional master station to communicate with multiple local substations within the area under its jurisdiction; The oscillation characteristic quantity data acquisition and upload module is used to perform real-time calculations on the voltage and current sampling sequences at the local substation to obtain a set of broadband oscillation characteristic quantity data, and upload the oscillation characteristic quantity data with time stamps to the regional master station; The regional-level power-off line set generation and distribution module is used by the regional master station to align the oscillation characteristic data sent by the local substations through time scales. It then performs line oscillation analysis based on the topology of the power grid lines in the entire region, the load level of the lines, and the broadband oscillation characteristics of each line. It then generates a regional-level power-off line set and distributes it to the local substations. The local cutting line set generation module is used by the local substation to implement a localized broadband oscillation control strategy based on the local real-time identification of the oscillation mode, thereby forming a local cutting line set that is conducive to local stability. The coordination control module is used to collect and analyze the regional-level power-off line set received by the local substation from the regional master station, and then select and remove the power-off line set determined locally. This prioritizes regional stability and selects and removes the power-off lines for this round. If the regional master station fails, the local substation will autonomously execute the local control strategy to quell local broadband oscillations. The iterative module is used to determine whether the area is stable after a delay after line removal. If it is unstable, the iterative module repeatedly runs the oscillation characteristic data acquisition and upload module, the regional-level line removal set generation and download module, the local line removal set generation module, and the coordination control module until the area is stable or all oscillating lines are removed.

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