New energy transient stability optimization method for controlling and adjusting through new energy station distribution energy storage

Abstract

The invention provides a new energy transient stability optimization method based on new energy station energy distribution and storage control adjustment, and relates to the technical field of power systems.The new energy transient stability optimization method comprises the steps that new energy station access node positions, installed capacity and operation mode data of a target power grid system are collected, and a power grid simulation model comprising a new energy station, an energy storage system and load characteristics is constructed; calculating a shrinkage admittance matrix after the new energy station is accessed, simulating a fault scene through time domain simulation, and generating a stable and unstable balance point of the unit; then calculating transient critical energy of fault scenes in different operation modes based on an energy function method; and finally, generating a transient stability risk margin through a difference value between the transient energy and the critical energy at the fault clearing moment, thereby evaluating the transient stability risk of the power grid after the new energy is accessed. According to the method, through dynamic adjustment of the energy storage system, the transient stability of the power grid after new energy grid connection is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of power system technology, specifically to a method for optimizing the transient stability of new energy sources through control and adjustment of energy storage at new energy stations. Background Technology

[0002] With the large-scale grid connection of renewable energy generation, the transient stability of the power system faces new challenges. The integration of renewable energy power plants alters the power flow distribution and dynamic characteristics of the traditional power grid. Especially under fault scenarios, the low inertia and weak damping characteristics of renewable energy units may lead to problems such as power angle instability and frequency fluctuations. In existing technologies, grid transient stability analysis is mainly based on the model of traditional synchronous generators, lacking a precise characterization of the dynamic characteristics of renewable energy power plants and failing to fully consider the regulatory role of energy storage systems during transient processes. Furthermore, traditional methods struggle to quantify the transient stability risks after renewable energy integration, resulting in insufficient assessment of the grid's safety margin and an inability to effectively guide the dynamic adjustment of energy storage systems, thus hindering the high-proportion consumption of renewable energy.

[0003] In the prior art, CN118232339A discloses a transient stability analysis method for new energy grid access during the planning stage. Based on the operating parameters of the power grid and multiple new energy power stations, an operating model of the power grid is constructed, and the first admittance information of the grid nodes after the multiple new energy power stations are connected to the grid is obtained. Based on the fault factors of the power grid and the operating model, the instability power angle information of the generator units within the grid is obtained when transient instability occurs under different operating conditions after the multiple new energy power stations are connected to the grid, and the transient power angle information of the generator units at preset fault times under different operating conditions is also obtained. Based on the first admittance information, the instability power angle information, and the transient power angle information, the configuration scheme of the reactive power compensation device for each new energy power station is determined.

[0004] The main problems with the above scheme are: calculations are based on grid parameters and preset fault scenarios in the planning stage, without taking into account the power fluctuations and dynamic changes in load during the actual operation of new energy power plants, resulting in deviations between the calculation results and the actual transient response; analysis is conducted through preset fault factors and instability power angles, but the transient stability margin under different operating modes is not clearly quantified, resulting in poor adaptability of the scheme; and the reactive power compensation requirements of each new energy power plant are calculated independently without considering the mutual influence of multiple new energy power plants during the transient process.

[0005] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a method for optimizing the transient stability of new energy sources through the control and adjustment of energy storage in new energy stations, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for optimizing the transient stability of new energy sources through control and adjustment of energy storage at new energy stations, comprising the following steps:

[0009] Step 1: Collect the installed capacity of the new energy power stations and their node locations connected to the target power grid system, and collect the operation mode of the DC receiving-end grid of the target power grid system under different start-up combinations, load levels and grid structures. Construct a grid simulation model of the target power grid system, which includes the dynamic characteristics of new energy power stations, energy storage systems and loads.

[0010] Step 2: Calculate the contraction admittance matrix of the power grid after the new energy power station is connected in the power grid simulation model, set the steady state of the unit, and determine the rotor angle of each unit under the steady state to generate a set of stable equilibrium points. Perform time-domain simulation on the power grid simulation model to simulate the rotor angle of each unit under the fault scenario. Generate the set of unstable equilibrium points of the unit based on the set of stable equilibrium points of the unit and the rotor angle of each unit under the fault scenario.

[0011] Step 3: Set up different fault scenarios and calculate the transient critical energy of the target power grid system under a single fault scenario based on the energy function method;

[0012] Step 4: Set the fault clearing time, calculate the transient energy corresponding to the fault clearing time under the same fault scenario after connecting a group of new energy power stations, generate a transient stability risk margin based on the transient critical energy and the transient energy corresponding to the fault clearing time, and judge the transient stability risk of the target power grid system after connecting the group of new energy power stations based on the value of the transient stability risk margin.

[0013] Furthermore, a new energy power station refers to a collection of multiple new energy generating units, with the entire new energy power station connected to the power grid at the node.

[0014] The data required to build a power grid simulation model includes:

[0015] The data on new energy power stations specifically includes the specific node location where the new energy power station is connected to the target power grid system, the total installed capacity of the new energy power station, the type of new energy, and the power output curve of the new energy power station;

[0016] Energy storage system data: The energy storage system is an auxiliary part of the new energy power station. The data includes the rated power, energy capacity, charging and discharging efficiency and response time of the energy storage system, as well as the charging and discharging logic of the energy storage system.

[0017] Basic power grid data specifically includes the connection relationships of nodes and branches in the target power grid system, line impedance, transformer turns ratio and generator dynamic parameters, static load and dynamic load;

[0018] Operation mode data, specifically including different generator start-stop states and output distribution, load peaks and valleys at different times, and grid segmentation;

[0019] Based on the aforementioned power grid basic data, a power grid basic model is established in the power system simulation software. New energy power plant models are connected at the corresponding node locations, and loads are set for the power grid basic model based on static and dynamic loads. At the same time, different operating modes are configured to generate a power grid simulation model.

[0020] Furthermore, the formula used to calculate the contraction admittance matrix of the power grid after the integration of new energy power plants is as follows:

[0021]

[0022] Among them, Y q Y represents the contraction admittance matrix of the power grid system. m,m Y represents the mutual admittance matrix of all generator units in the power grid, m represents the number of generator units in the power grid system, and Y represents the mutual admittance matrix of all generator units in the power grid system. m,m The element in is Y m,m (x, z) represents the admittances of the x-th and z-th generators, where x and z are the indices of the generator sets, and x ≠ z. m,w Y represents the mutual admittance matrix between generator units and other non-generator units, w represents the number of non-generator units in the power grid system, and Y represents the mutual admittance matrix between generator units and other non-generator units. m,w The element in is Y m,w (x, z′) represents the admittance between the x-th generator set and the z′-th non-generator set, where z′ represents the index of the non-generator set. w,m Y represents m,w The transpose of the matrix Y w,w Y represents the mutual admittance matrix between non-generator units. w,w The element in is Y w,w (x′, z′) represents the admittance between the x′-th and z′-th non-generator sets, where x′ represents the index of the non-generator set that is different from z′.

[0023] Furthermore, the principle upon which the set of stable equilibrium points for the unit is based is as follows:

[0024]

[0025] Where, θ S Represents the set of stable equilibrium points. This represents the rotor angle of the k-th generating unit under steady-state operation of the power grid, where k represents the index of the generating unit.

[0026] For a specific fault, fault simulation calculations are performed on the power grid simulation model of the power system after the integration of new energy sources. The fault time is gradually extended until the power system experiences transient power angle instability. The rotor angle of the unit under the fault scenario is obtained, and then the set of unstable equilibrium points of the unit is calculated. The formula used is as follows:

[0027]

[0028] Where, θ u Represents the set of unstable equilibrium points. This represents the rotor angle of the k-th unit under the fault scenario.

[0029] Furthermore, the principles underlying the setting of different fault scenarios are as follows:

[0030] The specific fault scenarios include: fault type, fault location, fault duration, and fault impact range;

[0031] The fault types include short-circuit faults, open-circuit faults, combined faults, and internal equipment faults; the fault locations include electrical equipment, power grid levels, and the distance between the fault point and the power source; the fault durations include transient faults and permanent faults; and the fault impact ranges include local impacts and cascading impacts.

[0032] Furthermore, the principle underlying the generation of transient critical energy is as follows:

[0033] The rotor motion equation of the generator rotor in the reference coordinates of the center of inertia is:

[0034]

[0035] C xz =E x E z B xz

[0036] D xz =E x E z G xz

[0037] Among them, M x Let x represent the moment of inertia of the x-th generator, where x and z represent the indices of the generators. Let P represent the angular velocity of the x-th generator relative to the center of inertia. m,x P represents the mechanical power of the x-th generator. e,x M represents the electromagnetic power of the x-th generator, where X represents the number of generators in the system. T P represents the total moment of inertia of the generators within the system. COI C represents the total unbalanced power at the center of inertia. xzD represents the synchronous torque coefficient. xz E represents the damping torque coefficient. x E represents the magnitude of the internal electromotive force of generator x. z B represents the amplitude of the internal electromotive force of generator z. xz G represents the real part of the element in the x-th row and z-th column of the node shrinkage admittance matrix. xz This represents the imaginary part of the element in the x-th row and z-th column of the node shrinkage admittance matrix;

[0038] Based on the above formula, the expression for the system's transient energy function is:

[0039]

[0040] Where V represents the transient energy function, Let θ represent the rotor angle of the x-th generator at its stable equilibrium point. xz This represents the angle difference between the x-th and z-th generators. This represents the angle difference between the x-th and z-th generators at the stable equilibrium point.

[0041] Based on the unstable equilibrium point under the fault scenario, the transient critical energy of the system under this fault scenario is calculated using the following formula:

[0042]

[0043] Among them, V cr This represents the transient critical energy. This represents the rotor angle of the x-th generator at the unstable equilibrium point. The angle between the x-th and z-th generators represents the relative angle at the unstable equilibrium point.

[0044] Furthermore, the principle underlying the generation of transient stability risk margin is as follows:

[0045] The transient energy at the fault clearing moment is calculated based on the transient energy function, using the following formula:

[0046]

[0047] Among them, V t This represents the transient energy at the fault clearing time, where t represents the fault clearing time. This represents the rotor angle of the x-th generator at the moment the fault is cleared. This represents the angle difference between the x-th and z-th generators at the moment of fault clearing;

[0048] The formula used to calculate the transient stability risk margin is:

[0049] ΔV=V cr -V t

[0050] Where ΔV represents the transient stability risk margin.

[0051] Furthermore, the principle underlying the assessment of transient stability risk based on transient stability risk margin is as follows:

[0052] When ΔV > 0, the transient energy of the system is lower than the critical energy, and the system is transiently stable.

[0053] When -1≤ΔV<0, the transient energy of the system is close to or at the critical energy, and the transient stability margin is insufficient, but the system does not directly become unstable.

[0054] When ΔV < -1, the transient energy of the system is higher than the critical energy, and the system becomes unstable.

[0055] Compared with the prior art, the beneficial effects of the present invention are:

[0056] This invention collects key data such as the location of access nodes, installed capacity, and operation mode of renewable energy power plants, and then establishes a power grid simulation model that includes the dynamic characteristics of renewable energy power plants, energy storage systems, and loads. It considers various operating modes, including different start-up combinations, peak / valley loads, and grid structures, covering typical and extreme power grid conditions, providing a high-precision simulation foundation for subsequent transient stability optimization. By calculating the shrinkage admittance matrix after renewable energy power plant access, it accurately reflects the impact of renewable energy grid connection on the grid impedance characteristics, solving the problem that traditional static models cannot capture dynamic interactions. Furthermore, by simulating fault scenarios in the time domain, it generates stable and unstable equilibrium points, quantifying the critical state of the system under disturbances, providing a data foundation for subsequent transient stability analysis. Dynamically correcting the admittance matrix ensures that the model is updated in real time with renewable energy access, avoiding the errors of traditional fixed-parameter models.

[0057] This invention also calculates the transient critical energy of the fault scenario under different operating modes using the energy function method, quantifying the stability limit of the system under fault conditions, providing a more accurate stability assessment standard, and avoiding misjudgments caused by conservative or aggressive threshold settings. By comparing the transient energy and critical energy at the fault clearing time, the energy storage charging and discharging strategy can be adjusted in real time to make up for the energy difference. By directly linking the energy margin to the urgency of energy storage actions, precise scheduling of energy storage resources is achieved, thereby more effectively suppressing transient instability. By calculating the difference between the transient energy and the transient critical energy at the fault clearing time, the transient stability risk is transformed into a quantifiable indicator, improving the reliability of the judgment. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the method flow of an embodiment of the present invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0060] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0061] Example:

[0062] Please see Figure 1 The present invention provides a technical solution:

[0063] A method for optimizing the transient stability of new energy sources through control and adjustment of energy storage at new energy stations, comprising the following steps:

[0064] Step 1: Collect the installed capacity of the new energy power stations and their node locations connected to the target power grid system, and collect the operation mode of the DC receiving-end grid of the target power grid system under different start-up combinations, load levels and grid structures. Construct a grid simulation model of the target power grid system, which includes the dynamic characteristics of new energy power stations, energy storage systems and loads.

[0065] In this embodiment, a new energy power station refers to a collection of multiple new energy units, and the entire new energy power station is connected to the power grid at the node.

[0066] The data required to build a power grid simulation model includes:

[0067] The data on new energy power stations specifically includes the specific node location where the new energy power station is connected to the target power grid system, the total installed capacity of the new energy power station, the type of new energy, and the power output curve of the new energy power station;

[0068] Energy storage system data: The energy storage system is an auxiliary part of the new energy power station. The data includes the rated power, energy capacity, charging and discharging efficiency and response time of the energy storage system, as well as the charging and discharging logic of the energy storage system.

[0069] Basic power grid data specifically includes the connection relationships of nodes and branches in the target power grid system, line impedance, transformer turns ratio and generator dynamic parameters, static load and dynamic load;

[0070] Operation mode data, specifically including different generator start-stop states and output distribution, load peaks and valleys at different times, and grid segmentation;

[0071] Based on the aforementioned power grid basic data, a power grid basic model is established in the power system simulation software. New energy power plant models are connected at the corresponding node locations, and loads are set for the power grid basic model based on static and dynamic loads. At the same time, different operating modes are configured to generate a power grid simulation model.

[0072] When constructing a power grid simulation model, the power system simulation software DIgSILENT is used. The PowerFactory is used to build the network. It takes the node and branch data of the power grid as input and constructs a complete network topology to form the basic power grid model. New energy power station models are connected to the corresponding nodes, specifically wind power and photovoltaic (PV). The wind power model is a doubly-fed induction generator (DFIG) model, and the PV model includes PV arrays and inverter models. Power output curves and control parameters for the new energy power stations are set. Energy storage models, specifically battery energy storage systems (BESS), are connected to designated nodes. The charging and discharging characteristics and control strategies of the BESS are set based on actual application scenarios. Charging and discharging characteristics include charging and discharging efficiency and SOC limits, while control and measurement include power command tracking and droop control. Load models are configured for the basic power grid model based on static and dynamic loads. Static load models include constant power, constant impedance, and constant current configurations, while dynamic loads are induction motor models. Based on this, the power grid operation modes are configured, specifically including DC receiving-end grid parameters and operation mode combinations. DC receiving-end grid parameters include converter station location, DC power transmission capacity, and constant power or constant voltage control modes. Operation mode combinations include different start-up combinations, load levels, and grid structures.

[0073] Step 2: Calculate the contraction admittance matrix of the power grid after the new energy power station is connected in the power grid simulation model, set the steady state of the unit, and determine the rotor angle of each unit under the steady state to generate a set of stable equilibrium points. Perform time-domain simulation on the power grid simulation model to simulate the rotor angle of each unit under the fault scenario. Generate the set of unstable equilibrium points of the unit based on the set of stable equilibrium points of the unit and the rotor angle of each unit under the fault scenario.

[0074] In this embodiment, the formula used to calculate the contraction admittance matrix of the power grid after the new energy power station is connected is:

[0075]

[0076] Among them, Y qY represents the contraction admittance matrix of the power grid system. m,m Y represents the mutual admittance matrix of all generator units in the power grid, m represents the number of generator units in the power grid system, and Y represents the mutual admittance matrix of all generator units in the power grid system. m,m The element in is Y m,m (x, z) represents the admittances of the x-th and z-th generators, where x and z are the indices of the generator sets, and x ≠ z. m,w Y represents the mutual admittance matrix between generator units and other non-generator units, w represents the number of non-generator units in the power grid system, and Y represents the mutual admittance matrix between generator units and other non-generator units. m,w The element in is Y m,w (x, z′) represents the admittance between the x-th generator set and the z′-th non-generator set, where z′ represents the index of the non-generator set. w,m Y represents m,w The transpose of the matrix Y w,w Y represents the mutual admittance matrix between non-generator units. w,w The element in is Y w,w (x′, z′) represents the admittance between the x′th and z′th non-generator sets, where x′ represents the index of the non-generator set that is different from z′.

[0077] Y q This represents the admittance matrix of the entire power grid system when renewable energy power plants are connected. It includes the admittance relationships between all generator nodes and non-generator nodes, reflecting the topology of the entire power grid. After the renewable energy power plants are connected, Y... q Dynamic updates occur due to changes caused by the addition of new nodes; in power systems, the dynamic differences between generator nodes and non-generator nodes are significant. The coupling relationships between generators and non-generators are described separately using a block matrix approach, Y. m,m This represents the electrical coupling relationship between generator nodes, reflecting the synchronous torque and damping characteristics between units; the matrix dimension is m×m. m,w and Y w,m The mutual admittance matrix represents the interaction between generator sets and non-generator sets, used to describe the interaction between generator sets and non-generator nodes such as loads and energy storage. It reflects the impact of new energy grid connection and load dynamic characteristics. w,w This represents the mutual admittance matrix between non-generator units, used to describe the self-admittance and mutual admittance between non-generator nodes such as loads and energy storage.

[0078] The principle underlying the setting of the unit's stable equilibrium point set is as follows:

[0079]

[0080] Where, θ s Represents the set of stable equilibrium points. This represents the rotor angle of the k-th generating unit under steady-state operation of the power grid, where k represents the index of the generating unit.

[0081] For a specific fault, fault simulation calculations are performed on the power grid simulation model of the power system after the integration of new energy sources. The fault time is gradually extended until the power system experiences transient power angle instability. The rotor angle of the unit under the fault scenario is obtained, and then the set of unstable equilibrium points of the unit is calculated. The formula used is as follows:

[0082]

[0083] Where, θ u Represents the set of unstable equilibrium points. This represents the rotor angle of the k-th unit under the fault scenario.

[0084] The set of stable equilibrium points reflects the synchronous state of the generator units in the target power grid system during normal steady-state operation. At this time, the mechanical and electromagnetic power of all generators are balanced, the rotor angle is constant, and the system is in a stable operating state. The stable equilibrium point defines the boundary of system stability. The unstable equilibrium point is the critical state in which the system cannot recover synchronous operation under fault disturbance. The rotor angle will continue to increase, and the system will gradually become unstable. The set of unstable equilibrium points reflects the critical point of the system transitioning from stability to instability under fault scenarios. It is a quantitative indicator of the transient stability limit. By gradually extending the fault time through time-domain simulation until the system becomes unstable, the rotor angle at the critical moment is recorded. The difference between the rotor angle at the critical moment and the stable equilibrium is the offset relative to the stable state, which represents the limit of the system's transient stability. If the rotor angle exceeds this limit after the fault is cleared, the system will not be able to recover synchronous operation.

[0085] Step 3: Set up different fault scenarios and calculate the transient critical energy of the target power grid system under a single fault scenario based on the energy function method;

[0086] In this embodiment, the principle underlying the setting of different fault scenarios is as follows:

[0087] The specific fault scenarios include: fault type, fault location, fault duration, and fault impact range;

[0088] The fault types include short-circuit faults, open-circuit faults, combined faults, and internal equipment faults; the fault locations include electrical equipment, power grid levels, and the distance between the fault point and the power source; the fault durations include transient faults and permanent faults; and the fault impact ranges include local impacts and cascading impacts.

[0089] The principle underlying the generation of transient critical energy is:

[0090] The rotor motion equation of the generator rotor in the reference coordinates of the center of inertia is:

[0091]

[0092] C xz =E x E z B xz

[0093] D xz =E x E z G xz

[0094] Among them, M x Let x represent the moment of inertia of the x-th generator, where x and z represent the indices of the generators. Let P represent the angular velocity of the x-th generator relative to the center of inertia. m,x P represents the mechanical power of the x-th generator. e,x M represents the electromagnetic power of the x-th generator, where X represents the number of generators in the system. T P represents the total moment of inertia of the generators within the system. COI C represents the total unbalanced power at the center of inertia. xz D represents the synchronous torque coefficient. xz E represents the damping torque coefficient. x E represents the magnitude of the internal electromotive force of generator x. z B represents the amplitude of the internal electromotive force of generator z. xz G represents the real part of the element in the x-th row and Z-th column of the node shrinkage admittance matrix. xz This represents the imaginary part of the element in the x-th row and z-th column of the node shrinkage admittance matrix;

[0095] In the rotor motion equation, Let P represent the inertial torque of the x-th generator. m,x -P e,x This represents the difference between mechanical power and electromagnetic power, i.e., the net acceleration power of the rotor. It is the center of inertia correction term, used to eliminate the influence of the overall system acceleration on the dynamics of the individual machine, and to ensure that the equations hold in the center of inertia coordinate system.

[0096] Based on the above formula, the expression for the system's transient energy function is:

[0097]

[0098] Where V represents the transient energy function, Let θ represent the rotor angle of the x-th generator at its stable equilibrium point. xz This represents the angle difference between the x-th and z-th generators. This represents the angle difference between the x-th and z-th generators at the stable equilibrium point.

[0099] The transient energy function transforms the dynamic behavior of a power system into an energy form, quantifying the changes in kinetic and potential energy of the system under fault disturbances. The kinetic energy component reflects the kinetic energy when the generator rotor angular velocity deviates from the synchronous speed. It is determined by the rotor inertia and angular velocity. The greater the kinetic energy, the higher the risk of system instability. The potential energy component includes power-angular potential energy and electrical coupling potential energy. This is power-angle potential energy, reflecting the change in potential energy caused by the imbalance between the mechanical power and electromagnetic power of the generator. It is the electrical coupling potential energy, reflecting the interaction between the synchronous torque and damping torque between generators.

[0100] Based on the unstable equilibrium point under the fault scenario, the transient critical energy of the system under this fault scenario is calculated using the following formula:

[0101]

[0102] Among them, V cr This represents the transient critical energy. This represents the rotor angle of the x-th generator at the unstable equilibrium point. The angle between the x-th and z-th generators represents the relative angle at the unstable equilibrium point.

[0103] The core of calculating the transient critical energy is to assess transient stability by quantifying the energy state of the power system under fault disturbances. The energy function method transforms the dynamic behavior of the power system into an energy form, converting the transient stability problem into an energy comparison problem. If the transient energy of the system during a fault exceeds the critical energy, it becomes unstable; otherwise, it remains stable. cr It reflects the minimum energy required for the system to recover from an unstable equilibrium point to a stable equilibrium point, and represents the maximum energy disturbance the system can withstand under fault conditions. By measuring the difference between the unstable equilibrium point and the stable equilibrium point, it quantifies the energy difference between the system's critical unstable state and its stable state. This represents the power-angle difference between the generator in its critical instability state and its steady state, reflecting the contribution of the power angle deviation to the potential energy. (C) xz and D xz V represents the synchronizing torque coefficient and the damping torque coefficient, respectively, determined by the real and imaginary parts of the admittance matrix, and is used to describe the electrical coupling strength between generators. cr This is the upper limit of energy required for the system to maintain transient stability. Exceeding this value will cause the power angle to become unstable, and different fault scenarios will lead to V cr The smaller the value, the weaker the system's ability to resist disturbances.

[0104] Step 4: Set the fault clearing time, calculate the transient energy corresponding to the fault clearing time under the same fault scenario after connecting a group of new energy power stations, generate a transient stability risk margin based on the transient critical energy and the transient energy corresponding to the fault clearing time, and judge the transient stability risk of the target power grid system after connecting the group of new energy power stations based on the value of the transient stability risk margin.

[0105] In this embodiment, the principle underlying the generation of transient stability risk margin is as follows:

[0106] The transient energy at the fault clearing moment is calculated based on the transient energy function, using the following formula:

[0107]

[0108] Among them, V t This represents the transient energy at the fault clearing time, where t represents the fault clearing time. This represents the rotor angle of the x-th generator at the moment the fault is cleared. This represents the angle difference between the x-th and z-th generators at the moment of fault clearing;

[0109] The formula used to calculate the transient stability risk margin is:

[0110] ΔV=V cr -V t

[0111] Where ΔV represents the transient stability risk margin.

[0112] The transient critical energy is the upper limit of energy that a system can maintain stability under fault conditions. If the transient energy of the system exceeds this value during a fault, the system will become unstable. The transient energy at the moment of fault clearing refers to the total dynamic energy accumulated by all generators and energy storage devices in the system at the instant the fault is cleared after a power system fault occurs. It reflects the kinetic and potential energy stored in the system due to disturbances during the fault period. When ΔV > 0, i.e., V cr >V t When the energy margin is sufficient, it indicates that the system has enough energy to recover and stabilize; otherwise, it may become unstable.

[0113] The principle underlying the assessment of transient stability risk based on transient stability risk margin is as follows:

[0114] When ΔV > 0, the transient energy of the system is lower than the critical energy, and the system is transiently stable.

[0115] When -1≤ΔV<0, the transient energy of the system is close to or at the critical energy, and the transient stability margin is insufficient, but the system does not directly become unstable.

[0116] When ΔV < -1, the transient energy of the system is higher than the critical energy, and the system becomes unstable.

[0117] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0118] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0119] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0120] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for optimizing the transient stability of new energy sources through control and adjustment of energy storage in new energy stations, characterized in that, The specific steps include: Step 1: Collect the installed capacity of the new energy power stations and their node locations connected to the target power grid system, and collect the operation mode of the DC receiving-end grid of the target power grid system under different start-up combinations, load levels and grid structures. Construct a grid simulation model of the target power grid system, which includes the dynamic characteristics of new energy power stations, energy storage systems and loads. Step 2: Calculate the contraction admittance matrix of the power grid after the new energy power station is connected in the power grid simulation model, set the steady state of the unit, and determine the rotor angle of each unit under the steady state to generate a set of stable equilibrium points. Perform time-domain simulation on the power grid simulation model to simulate the rotor angle of each unit under the fault scenario. Generate the set of unstable equilibrium points of the unit based on the set of stable equilibrium points of the unit and the rotor angle of each unit under the fault scenario. Step 3: Set up different fault scenarios and calculate the transient critical energy of the target power grid system under a single fault scenario based on the energy function method; Step 4: Set the fault clearing time, calculate the transient energy corresponding to the fault clearing time under the same fault scenario after connecting a group of new energy power stations, generate a transient stability risk margin based on the transient critical energy and the transient energy corresponding to the fault clearing time, and judge the transient stability risk of the target power grid system after connecting the group of new energy power stations based on the value of the transient stability risk margin.

2. The method for optimizing the transient stability of new energy sources through control and adjustment of energy storage at new energy stations, as described in claim 1, is characterized in that: In step 1, the new energy power station refers to a collection of multiple new energy units, and the entire new energy power station is connected to the power grid at the node. The data required to build a power grid simulation model includes: The data on new energy power stations specifically includes the specific node location where the new energy power station is connected to the target power grid system, the total installed capacity of the new energy power station, the type of new energy, and the power output curve of the new energy power station; Energy storage system data: The energy storage system is an auxiliary part of the new energy power station. The data includes the rated power, energy capacity, charging and discharging efficiency and response time of the energy storage system, as well as the charging and discharging logic of the energy storage system. Basic power grid data specifically includes the connection relationships of nodes and branches in the target power grid system, line impedance, transformer turns ratio and generator dynamic parameters, static load and dynamic load; Operation mode data, specifically including different generator start-stop states and output distribution, load peaks and valleys at different times, and grid segmentation; Based on the aforementioned power grid basic data, a power grid basic model is established in the power system simulation software. New energy power plant models are connected at the corresponding node locations, and loads are set for the power grid basic model based on static and dynamic loads. At the same time, different operating modes are configured to generate a power grid simulation model.

3. The method for optimizing the transient stability of new energy sources through control and adjustment of energy storage at new energy stations, as described in claim 1, is characterized in that: The formula used in step 2 to calculate the contraction admittance matrix of the power grid after the new energy power station is connected is: Among them, Y q Y represents the contraction admittance matrix of the power grid system. m,m Y represents the mutual admittance matrix of all generator units in the power grid, m represents the number of generator units in the power grid system, and Y represents the mutual admittance matrix of all generator units in the power grid system. m,m The element in is Y m,m (x, z) represents the admittances of the x-th and z-th generators, where x and z are the indices of the generator sets, and x ≠ z. m,w Y represents the mutual admittance matrix between generator units and other non-generator units, w represents the number of non-generator units in the power grid system, and Y represents the mutual admittance matrix between generator units and other non-generator units. m,w The element in is Y m,w (x,z ′ ), representing the x-th generator set and the z-th generator set. ′ Admittance between non-generator sets, z ′ Indicates the index of non-generator sets, Y w,m Y represents m,w The transpose of the matrix Y w,w Y represents the mutual admittance matrix between non-generator units. w,w The element in is Y w,w (x ′ ,z ′ ), representing the x-th ′ Taiwan and the zth ′ Admittance between non-generator sets, x ′ Indicates with z ′ Different non-generator set indexes.

4. The method for optimizing the transient stability of new energy sources through control and adjustment of energy storage at new energy stations, as described in claim 3, is characterized in that: The principle upon which the set of stable equilibrium points for the unit is set in step 2 is: Where, θ s Represents the set of stable equilibrium points. This represents the rotor angle of the k-th generating unit under steady-state operation of the power grid, where k represents the index of the generating unit. For a specific fault, fault simulation calculations are performed on the power grid simulation model of the power system after the integration of new energy sources. The fault time is gradually extended until the power system experiences transient power angle instability. The rotor angle of the unit under the fault scenario is obtained, and then the set of unstable equilibrium points of the unit is calculated. The formula used is as follows: Where, θ u Represents the set of unstable equilibrium points. This represents the rotor angle of the k-th unit under the fault scenario.

5. The method for optimizing the transient stability of new energy sources through control and adjustment of energy storage at new energy stations, as described in claim 1, is characterized in that: The principle underlying the setting of different fault scenarios in step 3 is as follows: The specific fault scenarios include: fault type, fault location, fault duration, and fault impact range; The fault types include short-circuit faults, open-circuit faults, combined faults, and internal equipment faults; the fault locations include electrical equipment, power grid levels, and the distance between the fault point and the power source; the fault durations include transient faults and permanent faults; and the fault impact ranges include local impacts and cascading impacts.

6. The method for optimizing the transient stability of new energy sources through control and adjustment of energy storage at new energy stations, as described in claim 5, is characterized in that: The principle underlying the generation of the transient critical energy in step 3 is as follows: The rotor motion equation of the generator rotor in the reference coordinates of the center of inertia is: C xz =E x E z B xz D xz =E x E z G xz Among them, M x Let x represent the moment of inertia of the x-th generator, where x and z represent the indices of the generators. Let P represent the angular velocity of the x-th generator relative to the center of inertia. m,x P represents the mechanical power of the x-th generator. e,x M represents the electromagnetic power of the x-th generator, where X represents the number of generators in the system. T P represents the total moment of inertia of the generators within the system. COI C represents the total unbalanced power at the center of inertia. xz D represents the synchronous torque coefficient. xz E represents the damping torque coefficient. x E represents the magnitude of the internal electromotive force of generator x. z B represents the amplitude of the internal electromotive force of generator z. xz G represents the real part of the element in the x-th row and z-th column of the node shrinkage admittance matrix. xz This represents the imaginary part of the element in the x-th row and z-th column of the node shrinkage admittance matrix; Based on the above formula, the expression for the system's transient energy function is: Where V represents the transient energy function, Let θ represent the rotor angle of the x-th generator at its stable equilibrium point. xz This represents the angle difference between the x-th and z-th generators. This represents the angle difference between the x-th and z-th generators at the stable equilibrium point. Based on the unstable equilibrium point under the fault scenario, the transient critical energy of the system under this fault scenario is calculated using the following formula: Among them, V cr This represents the transient critical energy. This represents the rotor angle of the x-th generator at the unstable equilibrium point. The angle between the x-th and z-th generators represents the relative angle at the unstable equilibrium point.

7. The method for optimizing the transient stability of new energy sources through control and adjustment of energy storage at new energy stations, as described in claim 6, is characterized in that: The principle underlying the generation of transient stability risk margin in step 4 is as follows: The transient energy at the fault clearing moment is calculated based on the transient energy function, using the following formula: Among them, V t This represents the transient energy at the fault clearing time, where t represents the fault clearing time. This represents the rotor angle of the x-th generator at the moment the fault is cleared. This represents the angle difference between the x-th and z-th generators at the moment of fault clearing; The formula used to calculate the transient stability risk margin is: ΔV=V cr -V t Where ΔV represents the transient stability risk margin.

8. The method for optimizing the transient stability of new energy sources through control and adjustment of energy storage at new energy stations, as described in claim 7, is characterized in that: The principle underlying the assessment of transient stability risk based on transient stability risk margin is as follows: When ΔV > 0, the transient energy of the system is lower than the critical energy, and the system is transiently stable. When -1≤ΔV<0, the transient energy of the system is close to or at the critical energy, and the transient stability margin is insufficient, but the system does not directly become unstable. When ΔV < -1, the transient energy of the system is higher than the critical energy, and the system becomes unstable.

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