Cooperative frequency regulation system and method for multi-transformer-area interconnected power system

Abstract

The invention belongs to the field of power system load frequency control, and relates to a cooperative frequency regulation system and method for a multi-zone-area interconnected power system. The method comprises the following steps: acquiring an area control error of each area according to inter-area tie line power deviation and system frequency deviation; constructing a memory output signal based on the historical data of the transformer area state; based on the memory output signal and the system state, utilizing a preset sliding mode surface function and solving according to a sliding mode control theory to obtain an equivalent control signal; and according to the equivalent control signal and a preset participation weight, generating and issuing a control instruction aiming at the traditional generator set, the electric vehicle cluster and the battery energy storage system so as to cooperatively adjust the system frequency. According to the system, cooperative adjustment of various heterogeneous resources in a multi-zone-area interconnection system is realized, the frequency adjustment effect is improved, the adjustment potential evaluation precision is improved, the accuracy and stability of frequency adjustment can be ensured, and the new energy consumption capability and operation flexibility of a power grid are effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of power system load frequency control, and relates to a coordinated frequency regulation system and method for multi-station interconnected power systems. Background Technology

[0002] Driven by the global energy transition and the "dual-carbon" strategy, a new power system based on new energy sources is being rapidly constructed. In this process, the high proportion of distributed power sources, represented by photovoltaics, and the widespread adoption of electric vehicles, while bringing significant clean energy benefits, also pose serious challenges to the safe and stable operation of the power system, especially the distribution network. On the one hand, electric vehicle charging loads are highly random and spatially concentrated, easily overlapping with traditional grid load peaks, leading to localized overloads and voltage exceedances. On the other hand, photovoltaic power generation output is significantly intermittent and volatile due to weather conditions, creating a sharp supply-demand mismatch with the equally uncertain charging load, severely restricting the grid's ability to absorb new energy and its operational flexibility.

[0003] To address these challenges, better resource utilization of adjustable loads such as electric vehicles has become a key research direction. Existing technologies mainly focus on improving the matching of distributed energy resources and loads within a single power station area through optimization algorithms, or on frequency regulation under simplified models. However, when facing complex scenarios such as high-proportion renewable energy penetration, aggregation of multiple types of heterogeneous resources (such as traditional units, energy storage, and electric vehicle clusters), and interconnection of multiple power stations, existing solutions still have significant limitations: First, the ability to dynamically characterize and online evaluate multiple uncertainties such as the output and charging behavior of photovoltaics and electric vehicles is insufficient, resulting in limited accuracy in evaluating regulation potential; second, the robustness of collaborative control strategies needs to be strengthened, and it is difficult to guarantee the accuracy and stability of frequency regulation under complex disturbances and communication constraints; third, research on comprehensive control systems for power mutual assistance and frequency coordination between multiple interconnected power stations is still insufficient, and there is a lack of global optimization schemes that can coordinate autonomy within a power station area and mutual assistance between power stations. Summary of the Invention

[0004] The purpose of this invention is to provide a coordinated frequency regulation system and method for multi-region interconnected power systems, in order to solve the technical problems of difficulty in accurately assessing multiple uncertain disturbances, insufficient robustness of coordinated control strategies, and decreased frequency regulation accuracy and stability in multi-region interconnected systems under high-proportion renewable energy access.

[0005] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides a coordinated frequency regulation system for a multi-station interconnected power system, wherein the multi-station interconnected power system includes at least two stations connected by a tie line; each station includes: a conventional generator set, a battery energy storage system, and a cluster of electric vehicles connected by an aggregator; The coordinated frequency adjustment system includes a controller configured to: The regional control error of each transformer area is obtained based on the power deviation of the inter-transformer tie lines and the frequency deviation of each transformer area. Obtain the status of each transformer area and construct a memory output signal based on the historical data of the transformer area status; Based on the regional control error, the memory output signal, and the station state, the equivalent control signal is obtained by using a preset sliding surface function and solving according to sliding mode control theory. Based on the equivalent control signal and the preset participation weights, control commands are generated and issued for the traditional generator set, the electric vehicle cluster, and the battery energy storage system to coordinately adjust the frequency of the multi-area interconnected power system.

[0006] Secondly, the present invention provides a method for coordinated frequency regulation of a multi-region interconnected power system, applied to a coordinated frequency regulation system for a multi-region interconnected power system, the method comprising: S1, obtain the power deviation of the inter-station tie line and the frequency deviation of each station area; S2, obtain the area control error of each substation based on the power deviation of the inter-substation tie line and the frequency deviation of each substation; S3, acquire the status of each transformer area, and construct a memory output signal based on the historical data of the transformer area status; S4. Based on the regional control error, the memory output signal, and the station state, the equivalent control signal is obtained by using a preset sliding surface function and solving according to sliding mode control theory. S5. Based on the equivalent control signal and the preset participation weight, generate and issue control commands for the traditional generator set, the electric vehicle cluster and the battery energy storage system to coordinately adjust the frequency of the multi-area interconnected power system.

[0007] Compared with the prior art, the present invention has the following beneficial effects: In this invention's multi-region interconnected power system, traditional generator sets serve as the fundamental support for stable power system operation. Battery energy storage systems possess flexible charging and discharging capabilities, absorbing excess energy for charging when the power system frequency is too high and releasing energy for discharging when the frequency is too low, thus balancing system power and stabilizing frequency. Electric vehicle charging loads exhibit strong randomness and spatiotemporal aggregation characteristics. After being connected to the multi-region interconnected power system via an aggregator, electric vehicle clusters can be managed and controlled as adjustable loads, adjusting charging or discharging behavior according to power system demand and participating in frequency regulation. This invention obtains the regional control error for each transformer area based on the power deviation of the interconnection lines between transformer areas and the frequency deviation of each area. The regional control error comprehensively reflects the power imbalance and frequency deviation of each transformer area, providing crucial information for subsequent frequency regulation. The transformer status of each area is acquired, and a memory output signal is constructed based on the historical data of the transformer status, making frequency regulation more forward-looking and adaptable, better able to cope with multiple uncertainties and disturbances. Based on the regional control error, the memory output signal, and the transformer area status, a preset sliding mode surface function is used, and an equivalent control signal is obtained according to sliding mode control theory. Sliding mode control has strong robustness, enabling the multi-transformer interconnected power system to still move according to the preset sliding mode surface even under complex disturbances and communication constraints, ensuring the accuracy and stability of frequency regulation. Based on the equivalent control signal and preset participation weights, control commands are generated and issued for the traditional generator sets, the electric vehicle clusters, and the battery energy storage system to coordinately regulate the frequency of the multi-transformer interconnected power system. This invention achieves coordinated regulation of various heterogeneous resources in a multi-transformer interconnected system, improves the frequency regulation effect, enhances the accuracy of regulation potential assessment, and ensures the accuracy and stability of frequency regulation under complex disturbances and communication constraints. It effectively improves the grid's ability to absorb new energy sources and its operational flexibility, ensuring the safe and stable operation of the multi-transformer interconnected power system.

[0008] This invention achieves coordinated regulation of various heterogeneous resources in a multi-region interconnected system by rationally allocating regulation tasks among different resources, fully leveraging the advantages of each resource, and improving frequency regulation effectiveness. By comprehensively considering the regional control errors of each region, utilizing memory output signals and sliding mode control theory to solve for equivalent control signals, and rationally allocating control commands, this invention achieves dynamic assessment and precise response to multiple uncertainties such as photovoltaic and electric vehicle output and charging behavior, improving the accuracy of regulation potential assessment. The coordinated control strategy of this invention has strong robustness, ensuring the accuracy and stability of frequency regulation under complex disturbances and communication constraints. This invention constructs a comprehensive control system for power mutual assistance and frequency coordination between multiple interconnected regions, coordinating intra-region autonomy and inter-region mutual assistance, achieving global optimization, effectively improving the grid's capacity to absorb new energy and its operational flexibility, and ensuring the safe and stable operation of the multi-region interconnected power system. Attached Figure Description

[0009] Figure 1 This is a simplified multi-zone interconnection structure diagram according to an embodiment of the present invention; Figure 2 The multi-zone interconnection of the present invention is the first embodiment of the present invention. Regional structure diagram; Figure 3 This is a flowchart of a method according to an embodiment of the present invention; Figure 4 This is a simplified model diagram of a single-diode photovoltaic power generation unit according to an embodiment of the present invention; Figure 5 This is a diagram showing the charging and discharging state of the energy storage system as a function of frequency deviation, according to an embodiment of the present invention. Figure 6 This is a frequency variation diagram of a multi-zone interconnection system according to an embodiment of the present invention; Figure 7 This is a diagram showing the power switching variation of a multi-zone interconnection system according to an embodiment of the present invention. Figure 8 This is a diagram showing the output power variation of a multi-zone interconnection system according to an embodiment of the present invention. Figure 9 This is a diagram showing the output power variation of an electric vehicle in a multi-zone interconnected system according to an embodiment of the present invention. Detailed Implementation

[0010] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0011] It should be noted that the terms "first," "second," etc., in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0012] The present invention will now be described in further detail with reference to the accompanying drawings: Example 1: See Figure 1 This is a diagram illustrating the interconnection structure of a multi-distribution power system, which includes at least two distribution areas connected by tie lines; the diagram shows... <1> to <36> As power nodes, T1 is the first transformer area, T2 is the second transformer area, and T3 is the third transformer area. The multi-transformer area interconnected power system of this invention includes three transformer areas. Each transformer area includes: a traditional generator set, a battery energy storage system, and a cluster of electric vehicles connected via an aggregator. See also... Figure 2 This is the first embodiment of the multi-zone interconnection of the present invention. A regional structure diagram, in which... For speed controller model, It is a steam turbine model. For the generator model, s is the integral operator, + represents positive feedback, and - represents negative feedback.

[0013] This invention discloses a coordinated frequency regulation system for a multi-region interconnected power system. The coordinated frequency regulation system includes a controller configured to: The regional control error for each transformer substation is obtained by calculating the power deviation of the interconnecting lines between substations and the frequency deviation of each substation. The regional control error can comprehensively reflect the power imbalance and frequency deviation of each substation, providing a crucial basis for subsequent frequency regulation.

[0014] In a preferred embodiment of the present invention, the formula for obtaining the regional control error is as follows:

[0015] in, For the station area index, For the current time, For the first Regional control error of each transformer area For the first Inter-regional interconnection line power deviation in each transformer area This is the frequency deviation coefficient. For the first Frequency deviation of each station area.

[0016] The status of each transformer substation is acquired, and a memory output signal is constructed based on the historical data of the substation status. The memory output signal takes into account the system's historical information, which helps to improve the system's responsiveness to dynamic changes, making frequency regulation more forward-looking and adaptable, and better able to cope with multiple uncertain disturbances.

[0017] In a preferred embodiment of the present invention, the formula for obtaining the memory output signal is as follows:

[0018] in, For the first The memory output signal of each station area The size of the historical data , For the first The output parameter matrix of each transformer area For the first The status of each station area.

[0019] In a preferred embodiment of the present invention, the transformer substation status includes at least the mechanical output power deviation of the conventional generator set, the governor position deviation of the conventional generator set, the power deviation of the tie line, the frequency deviation of each transformer substation, the aggregated output power of the electric vehicle cluster, and the output power of the battery energy storage system.

[0020] Based on the regional control error, the memory output signal, and the station state, an equivalent control signal is obtained by using a preset sliding mode surface function and solving according to sliding mode control theory. Sliding mode control has strong robustness, enabling the system to continue moving according to the preset sliding mode surface even when subjected to complex disturbances and communication constraints, thus ensuring the accuracy and stability of frequency regulation.

[0021] In a preferred embodiment of the present invention, the sliding surface function is specifically as follows:

[0022] in, For the first Sliding surface function of each platform area For the first The sliding surface parameter vectors for each platform area are selected to ensure... It is neither strange nor unusual. For the first The status of each transformer station area For the first The transformer state parameter matrix of each transformer area For integration variables The corresponding number The status of each transformer station area For the current time, The size of the historical data For the first Control signal parameter matrix for each transformer area For the first Controller gain for each station area For the first The integral value of the regional control error of each transformer station area.

[0023] In a preferred embodiment of the present invention, the expression for the equivalent control signal is as follows:

[0024] in, This is the equivalent sliding mode control signal. For the first External interference in individual transformer areas For the first The output parameter matrix of each transformer area For the first Historical averages or estimates of the status of each transformer substation.

[0025] In a preferred embodiment of the present invention, the dynamic relationship between the transformer area state, the transformer area state parameter matrix, the transformer area output parameter matrix, and the integral value of the area control error is defined by the following system state-space equation and system state dynamic equation: The system state-space equation is:

[0026]

[0027] in, For the first The derivative of the state of each transformer area. For the first The state parameter matrix of each station area For the first The status of each transformer station area For the first Control signal parameter matrix for each transformer area For the first Interference coefficient matrix of each station area For system output, For the first The output parameter matrix of each transformer area For the first External interference in each station area For the first Controller gain for each station area For the first Historical average or estimated value of the status of each transformer area For the first The equivalent perturbation matrix of each station area For the first The status of each transformer station area For the first The sliding surface parameter vectors for each platform area are selected to ensure... It is strange and unusual.

[0028] The dynamic equations of the system state are as follows:

[0029] in, For the first The differential mechanical output power deviation of each transformer area For the first Differential power deviation of inter-regional interconnection lines in each transformer area For the first The differential frequency deviation of each station area For the first The differential position deviation of the speed controller in each distribution zone For the first The differential output power of electric vehicles in each power station area The derivative of the output power of the battery energy storage system. For the first Mechanical output power deviation in each station area For the first Speed ​​controller position deviation in each station area For the first The time constant of the turbine / steam turbine in each distribution area For the first Inter-regional interconnection line power deviation in each transformer area For the first The first and second districts Inter-regional synchronization coefficient of each station area For the first Frequency deviation of each station area For adjacent Frequency deviation of each station area For the first The generator inertia constant of each transformer substation area For the first Damping coefficient of generators in each distribution area For the first Load deviation of each transformer area For the first The renewable energy output power of each substation area For the first The sagging coefficient of each platform area For the first The time constant of the speed controller in each distribution zone For the first The integral of ACE (Area Control Error) for each control zone. The participation ratio of traditional generator sets. For the first Control signals for each transformer area For the first The output power of electric vehicles in each power station area This represents the participation rate coefficient for electric vehicles. For the first Electric vehicle control coefficients for each district For the first The time constant of electric vehicles in each power station area For the output power of the battery energy storage system, The participation ratio of battery energy storage systems. For the control coefficient of the battery energy storage system, This represents the time constant of the battery energy storage system.

[0030] In a preferred embodiment of the present invention, the external disturbances or load deviations in the system state-space equations include the power output of the photovoltaic power generation unit, and the formula for obtaining the power output of the photovoltaic power generation unit is:

[0031] in, For the first The power output of the photovoltaic power generation units in each substation area For the gain of photovoltaic power generation units, It is a time constant. For the Laplace operator, For the first Solar irradiance intensity of each station area.

[0032] Based on the equivalent control signal and preset participation weights, control commands are generated and issued for the traditional generator sets, the electric vehicle clusters, and the battery energy storage system to coordinately regulate the frequency of the multi-region interconnected power system. By rationally allocating the regulation tasks of each resource, the coordinated regulation of various heterogeneous resources in the multi-region interconnected power system is achieved, giving full play to the advantages of each resource and improving the frequency regulation effect. This coordinated regulation of the power system frequency fully leverages the advantages of each resource.

[0033] In a preferred embodiment of the present invention, the step of generating and issuing control commands for the conventional generator set, the electric vehicle cluster, and the battery energy storage system based on the equivalent control signal and preset participation weights, wherein the controller is further configured to adaptively select the controller gain of the battery energy storage system according to the interval where the frequency deviation of the distribution area is located after the battery energy storage system receives the control command, as follows: When the frequency deviation of the substation is greater than the positive threshold of the dead zone of the response frequency change, the controller gain of the battery energy storage system is greater than zero, and the battery energy storage system is in a discharging state.

[0034] When the frequency deviation of the substation is greater than or equal to the negative threshold of the dead zone of the response frequency change and less than or equal to the positive threshold of the dead zone of the response frequency change, the controller gain of the battery energy storage system is equal to zero, and the battery energy storage system stops charging and discharging.

[0035] When the frequency deviation of the substation is less than the negative threshold of the dead zone of the response frequency change, the controller gain of the battery energy storage system is less than zero, and the battery energy storage system is in a charging state.

[0036] The formula for obtaining the controller gain of the battery energy storage system is as follows:

[0037] in, For discharge control gain, To control the charging gain, For the desired charging power ratio, For the desired discharge power ratio, A positive threshold for responding to frequency changes. The negative threshold for responding to frequency changes, The positive threshold for the dead zone in response to frequency changes, The negative threshold for the dead zone in response to frequency changes.

[0038] In a preferred embodiment of the present invention, the controller is further configured to monitor and manage the state of charge of the battery energy storage system when generating control commands for the battery energy storage system. The formula for obtaining the state of charge of the battery energy storage system is as follows:

[0039]

[0040] in, For the working performance of battery energy storage systems, Represents the initial value of the state of charge. Indicates the storage capacity of energy storage. The output power of the battery energy storage system. This refers to the output voltage of the battery energy storage system. This refers to the output current of the battery energy storage system.

[0041] In a preferred embodiment of the present invention, the participation weights include: participation weights for traditional generator sets, electric vehicles, and battery energy storage systems, and the participation weights for traditional generator sets, electric vehicles, and battery energy storage systems satisfy the following relationship:

[0042] in, For traditional generator sets to participate in the weighting, For electric vehicles to participate in the weighting, The weighting is assigned to the battery energy storage system.

[0043] This invention effectively solves the technical problems faced by multi-region interconnected systems with a high proportion of renewable energy access. By comprehensively considering the regional control errors of each region, using memory output signals and sliding mode control theory to solve for equivalent control signals, and rationally allocating control commands, it achieves dynamic assessment and precise response to multiple uncertainties such as photovoltaic and electric vehicle output and charging behavior, improving the accuracy of regulation potential assessment. The collaborative control strategy has strong robustness, ensuring the accuracy and stability of frequency regulation under complex disturbances and communication constraints. A comprehensive control system for power mutual assistance and frequency collaborative support between multiple interconnected regions is constructed, coordinating intra-region autonomy and inter-region mutual assistance, achieving global optimization, effectively improving the grid's ability to absorb renewable energy and its operational flexibility, and ensuring the safe and stable operation of the multi-region interconnected power system.

[0044] See Figure 3 A method for coordinated frequency regulation in a multi-region interconnected power system, applied to a coordinated frequency regulation system for a multi-region interconnected power system, the method comprising: S1, obtain the power deviation of the inter-station tie line and the frequency deviation of each station area.

[0045] S2, based on the power deviation of the interconnection lines between stations and the frequency deviation of each station, obtains the regional control error of each station. The regional control error can comprehensively reflect the power imbalance and frequency deviation of each station, providing a key basis for subsequent frequency regulation.

[0046] S3. Obtain the status of each transformer area and construct a memory output signal based on the historical data of the transformer area status. This helps to improve the response capability of the multi-transformer interconnected power system to dynamic changes, making frequency regulation more forward-looking and adaptable, and better able to cope with multiple uncertain disturbances.

[0047] S4. Based on the regional control error, the memory output signal, and the transformer area status, the equivalent control signal is obtained by using a preset sliding surface function and solving according to sliding mode control theory. Sliding mode control has strong robustness and can ensure that the interconnected power system of multiple transformer areas still moves according to the preset sliding surface when subjected to complex disturbances and communication constraints, thus ensuring the accuracy and stability of frequency regulation.

[0048] S5. Based on the equivalent control signal and the preset participation weight, control commands are generated and issued for the traditional generator set, the electric vehicle cluster and the battery energy storage system to coordinately adjust the frequency of the multi-area interconnected power system, realize the coordinated adjustment of various heterogeneous resources in the multi-area interconnected system, give full play to the advantages of each resource and improve the frequency regulation effect.

[0049] This invention fully leverages the advantages of various resources to improve frequency regulation performance. By comprehensively considering the regional control errors of each distribution area, it utilizes memory output signals and sliding mode control theory to solve for equivalent control signals and rationally allocates control commands. This enables dynamic assessment and precise response to multiple uncertainties related to photovoltaic power generation and electric vehicle power output and charging behavior, thereby improving the accuracy of regulation potential assessment. The collaborative control strategy of this invention exhibits strong robustness, ensuring the accuracy and stability of frequency regulation under complex disturbances and communication constraints. Furthermore, this invention constructs a comprehensive control system for power mutual assistance and frequency collaborative support between multiple interconnected distribution areas. It coordinates intra-area autonomy and inter-area mutual assistance, achieving global optimization, effectively enhancing the grid's capacity to absorb new energy and its operational flexibility, and ensuring the safe and stable operation of the multi-area interconnected power system.

[0050] Example 2: See Figure 1 This is a diagram illustrating the interconnection structure of a multi-regional power system. The multi-regional power system includes traditional generators, electric vehicle clusters, and battery energy storage systems. The diagram shows... <1> to <36> As power nodes, T1 is the first transformer area, T2 is the second transformer area, and T3 is the third transformer area. The multi-transformer area interconnected power system of this invention includes three transformer areas. Each transformer area includes: a traditional generator set, a battery energy storage system, and a cluster of electric vehicles connected via an aggregator. See also... Figure 2 This is the first embodiment of the multi-zone interconnection of the present invention. A regional structure diagram, in which... For speed controller model, It is a steam turbine model. For the generator model, s is the integral operator, + represents positive feedback, and - represents negative feedback.

[0051] This invention discloses a coordinated frequency regulation system for a multi-region interconnected power system. The multi-region interconnected power system has participation weights set according to the regulation capabilities provided by traditional generators, electric vehicle clusters, and battery energy storage systems. , and ,in, For generator sets to participate in weighting, For electric vehicles to participate in the weighting, For battery energy storage systems to participate in the weighting, and satisfy the following conditions: Since the participation of battery energy storage systems can smooth out fluctuations and improve the operational capability of multi-regional power generation systems, they should be given priority in the regulation of interconnected multi-regional power generation systems compared to power generation devices such as thermal power generators. Therefore, the participation weight is set to... .

[0052] Using photovoltaic (PV) panels, solar energy is converted into electric current that can be transmitted through wires. In theory, ideal solar energy can be modeled as a system integrating a photocurrent source and diodes. Variations in ambient temperature and solar irradiance affect the power supply of PV panels. To study the application of PV in substation power systems, a simplified PV power generation unit model can be constructed considering the relationships between various electronic components. An equivalent circuit model of a single-diode PV power generation unit is shown below. Figure 4 As shown.

[0053] To analyze the output power of a photovoltaic (PV) power generation unit, the photocurrent of the PV panel under illumination is considered. The current of the PV power generation unit is described by the following equation:

[0054] in, The current of the photovoltaic power generation unit. , , These are the photocurrent, diode current, and parallel resistor current, respectively.

[0055] When exposed to sunlight at a certain temperature, photovoltaic panels generate photocurrent, which is described by the following equation:

[0056] in, Photocurrent, Represents solar radiation intensity. Represents short-circuit current. Represents the temperature coefficient. Represents the temperature of the photovoltaic panel. This represents the rated temperature.

[0057] Diode current Described by the following equation:

[0058] in, This is the diode current. Indicates terminal voltage. Indicates the current of the photovoltaic power generation unit. Indicates series resistance. Represents the diode's ideality factor. Represents the Boltzmann constant. This is the saturation current.

[0059] Saturation current It can be described by the following formula:

[0060] in, It is the reverse current of the diode. It is the bandgap energy of the battery semiconductor. It is the charge of the electron.

[0061] In addition, the current of the parallel resistor It can be calculated using the following formula:

[0062] in, This refers to the voltage of the photovoltaic power generation unit. This is the resistance value of the parallel resistor.

[0063] The above equations provide the current, voltage, and other characteristics of the photovoltaic power generation unit, which can be used to describe the operation of the photovoltaic power generation unit in the system. Based on the above analysis, the power output of the photovoltaic power generation unit can be described by a first-order function, as shown in the following formula:

[0064] in, For the first The power output of the photovoltaic power generation units in each substation area For the gain of photovoltaic power generation units, It is a time constant. For the Laplace operator, For the first Solar irradiance intensity of each station area.

[0065] Power exchange between battery energy storage system and local power system The dynamic changes can be represented by the following function:

[0066] in: It is a time constant. For control signals, For the controller gain of the battery energy storage system, The derivative of the output power of the battery energy storage system. This provides the output power for the battery energy storage system.

[0067] The controller gain of the battery energy storage system is determined by the following formula. Behavior:

[0068] in, For discharge control gain, To control the charging gain, For the desired charging power ratio, For the desired discharge power ratio, A positive threshold for responding to frequency changes. The negative threshold for responding to frequency changes, The positive threshold for the dead zone in response to frequency changes, The negative threshold for the dead zone in response to frequency changes.

[0069] For interconnected power systems with battery storage, the frequency of the power system can be adjusted by changing the state of charge and discharge of the batteries. The main challenge in achieving this is identifying the charging and discharging status. Frequency deviation of power system in each region It can be used to determine the charging and discharging status of a battery energy storage system, where, For the first Frequency deviation of power system in each region For system reference frequency, This refers to the real-time frequency. Based on the interaction between the power system frequency and the battery energy storage system, the following can be determined:

[0070] Changes in system frequency directly reflect the balance of active power. When the total active power generated by generators in a power system balances the total active power consumed by the load, the system frequency can be maintained at the reference value. When power generation exceeds load demand, the system frequency increases, leading to… When power generation is less than load demand, the system frequency decreases. .

[0071] For a normally operating power system, the frequency fluctuations of the power distribution area are within a tolerable range. Therefore, based on the above analysis, the battery energy storage system will meet the following operating conditions: when At that time, the battery energy storage system is in a discharging state, and ; when At that time, the battery energy storage system stops charging and discharging, and It should be noted that, Dead zone for tolerable frequency deviation; when At that time, the battery energy storage system is in a charging state, and .

[0072] Figure 5 This demonstrates how battery energy storage systems change with frequency deviation. Power exchange characteristics under varying conditions.

[0073] Typically, SOC (State of Charge) is used as an indicator to analyze the performance of battery energy storage systems. Using the coulomb counting method, the performance formula for a battery energy storage system can be obtained:

[0074] in, For the working performance of battery energy storage systems, This represents the initial value of SOC. Indicates the storage capacity of energy storage. This refers to the output current of the battery energy storage system.

[0075] The output power of a battery energy storage system can be expressed as:

[0076] in, The output power of the battery energy storage system. This refers to the output voltage of the battery energy storage system. This refers to the output current of the battery energy storage system.

[0077] For ease of discussion, we can assume the output voltage of the battery energy storage system is... If the state of charge remains constant over a wide range, then the performance formula for the battery energy storage system can be rewritten as:

[0078] in, For the working performance of battery energy storage systems, Represents the initial value of the state of charge. Indicates the storage capacity of energy storage. The output power of the battery energy storage system. This is the output voltage of the battery energy storage system.

[0079] To enable electric vehicles (EVs) to participate in frequency regulation of the power grid in a distribution area, V2G (Vehicle-to-Grid) technology is typically used to control the charging and discharging states of EVs. However, the participation capability of a single EV is limited and its willingness to participate is unknown. Therefore, it is necessary to aggregate EVs within the distribution area via a communication network to enable them to participate in grid regulation. The integrated EVs consolidate their charging and discharging states under V2G through an aggregator, thereby obtaining a model of the EVs' ability to participate in distribution area regulation. The dynamic performance of EVs can be expressed as:

[0080] in, For the first The differential output power of electric vehicles in each power station area For the first The output power of electric vehicles in each power station area The participation coefficient for electric vehicles. For the first The time constant of electric vehicles in each power station area For the first Electric vehicle control coefficients for each district For the first Control signals for each station area.

[0081] based on Figure 5 Information transmission between devices can obtain the first The dynamic equations of the multi-station system are as follows:

[0082] in, For the first The differential mechanical output power deviation of each transformer area For the first Differential power deviation of inter-regional interconnection lines in each transformer area For the first The differential frequency deviation of each station area For the first The differential position deviation of the speed controller in each distribution zone For the first The differential output power of electric vehicles in each power station area The derivative of the output power of the battery energy storage system. For the first Mechanical output power deviation in each station area For the first Speed ​​controller position deviation in each station area For the first The time constant of the turbine / steam turbine in each distribution area For the first Inter-regional interconnection line power deviation in each transformer area For the first The first and second districts Inter-regional synchronization coefficient of each station area For the first Frequency deviation of each station area For adjacent Frequency deviation of each station area For the first The generator inertia constant of each transformer substation area For the first Damping coefficient of generators in each distribution area For the first Load deviation of each transformer area For the first The renewable energy output power of each substation area For the first The sagging coefficient of each platform area For the first The time constant of the speed controller in each distribution zone For the first The ACE points for each region The participation ratio of traditional generator sets. For the first Control signals for each transformer area For the first The output power of electric vehicles in each power station area This represents the participation rate coefficient for electric vehicles. For the first Electric vehicle control coefficients for each district For the first The time constant of electric vehicles in each power station area For the output power of the battery energy storage system, The participation ratio of battery energy storage systems. For the control coefficient of the battery energy storage system, This represents the time constant of the battery energy storage system.

[0083] Define the system state as The system output is the area control error. , This is the frequency deviation coefficient.

[0084] The system state-space equation is:

[0085] in, For the first The derivative of the state of each transformer area. For the first The state parameter matrix of each station area For the first The status of each transformer station area For the first Control signal parameter matrix for each transformer area For the first Interference coefficient matrix of each station area For system output, For the first The output parameter matrix of each transformer area For the first External interference of each transformer area, satisfying , For the first Load deviation in individual transformer areas It is a positive constant. And it has the following definition:

[0086]

[0087] , , , .

[0088] in, For the first Mechanical output power deviation in each station area For the first Speed ​​controller position deviation in each station area For the first Inter-regional interconnection line power deviation in each transformer area For the first Frequency deviation of each station area For the first The output power of electric vehicles in each power station area For the output power of the battery energy storage system, For the first Regional control error of each transformer area For the first The transformer state parameter matrix of each transformer area For the first The damping coefficient of the generator in each distribution area.

[0089] The sliding mode control strategy for the multi-zone system of this invention is as follows: A sliding mode control scheme was developed using historical output information from the power system. First, a definition is made... and ; in, For the first The ACE points for each region For the first Regional control error of each transformer area For the first The time derivative of the integral of the ACE of each station area.

[0090] Define the memory output signal as:

[0091] in, For the first The memory output signal of each station area The size of the historical data , For the first The output parameter matrix of each transformer area For the first The status of each station area.

[0092] The sliding surface containing historical output information is:

[0093] in, For the first Sliding surface function of each platform area For the first The sliding surface parameter vectors for each platform area are selected to ensure... It is neither strange nor unusual. For the first The status of each transformer station area For the first The transformer state parameter matrix of each transformer area For integration variables The corresponding number The status of each transformer station area For the current time, The size of the historical data For the first Control signal parameter matrix for each transformer area For the first Controller gain for each station area For the first The integral value of the regional control error of each transformer station area.

[0094] In some existing research, sliding mode surface design uses only the most recently transmitted signal or the current output signal. However, there are cases where the system trajectory exceeds the steady state, and using the signal at the moment of contact may misjudge the stability of the power system. In contrast, the proposed memory output sliding mode surface is designed based on historical output signals. Using multiple pieces of information can more accurately guarantee the stable state of the system and improve its robustness to a certain extent.

[0095] According to sliding mode control theory, a suitable sliding surface should satisfy... and Therefore, we can conclude that:

[0096] in, For the design of the first Sliding surface function of each platform area The rate of change of the mold surface, For the first The derivative of the state of each transformer zone.

[0097] Substituting the system state-space equations into equation (18), we get:

[0098] Therefore, the equivalent memory SMC (Sliding Mode Control) can be derived as:

[0099] in, This is the equivalent sliding mode control signal. For the first External interference in individual transformer areas For the first The output parameter matrix of each transformer area For the first Historical averages or estimates of the status of each transformer substation.

[0100] No. The state-space equation of a multi-station power system in a region is expressed as:

[0101] in: .

[0102] Among them, among them, For the first The derivative of the state of each transformer area. For the first The state parameter matrix of each station area For the first The status of each transformer station area For the first Control signal parameter matrix for each transformer area For the first Interference coefficient matrix of each station area For system output, For the first The output parameter matrix of each transformer area For the first External interference in each station area For the first Controller gain for each station area For the first Historical average or estimated value of the status of each transformer area For the first The equivalent perturbation matrix of each station area For the first The status of each transformer station area For the first The sliding surface parameter vectors for each platform area are selected to ensure... It is strange and unusual.

[0103] The simulation verification of the multi-zone interconnection system of this invention is as follows: Building such Figure 2 The system shown comprises three distribution substations of different sizes, each containing photovoltaic power generation units, a battery energy storage system, and a cluster of electric vehicles. The substations are connected via interconnecting lines. To illustrate the effectiveness of the coordinated control scheme, it is assumed that an imbalance between power generation and load demand causes instability in the substation system.

[0104] Frequency variations in multi-zone interconnection systems, such as Figure 6 As shown in the figure. The results show that under the control scheme of the present invention, the frequency of the multi-station system can reach a stable state, proving the effectiveness of the proposed scheme.

[0105] In a multi-transformer interconnection system, power exchange is achieved between transformer areas via tie lines. The dynamic change process of the exchanged power is as follows: Figure 7 As shown. In this multi-station interconnection system, the tie line serves a dual function: firstly, it is the physical channel for power transmission, enabling power exchange and support between stations; secondly, it is also a communication link for information exchange, transmitting key information such as load, power generation, energy storage status, and control commands from each station, supporting the system's collaborative decision-making. Under the collaborative scheduling and optimization scheme of this invention, the multi-station system continuously adjusts the operating status of controllable resources within each station through real-time information exchange and distributed computing. From Figure 7 As can be seen, with the advancement of the optimization process, the fluctuation range of the power exchanged via the tie lines between distribution stations gradually decreases, eventually approaching a near-zero equilibrium state. This convergence process indicates that the system is gradually reducing its dependence on external power exchange through the autonomous coordination and optimized allocation of internal resources. Physically speaking, when the load demand of each distribution station matches the local energy supply capacity such as distributed generation and energy storage in real time, i.e., when a local supply-demand balance is achieved, there will no longer be a net power difference between distribution stations. Therefore, there is no need for power exchange via tie lines, and the theoretical value of the tie line exchange power will stabilize near zero. This state not only reduces the transmission pressure and losses of the tie lines but also demonstrates the ability of a multi-distribution station system to achieve optimal overall resource allocation through collaborative optimization.

[0106] The output power variation of the multi-regional interconnected power system coordinated frequency regulation system is as follows: Figure 8As shown. Due to differences in the conditions of different power distribution areas, the capacity and energy of the battery energy storage systems in each area vary. Under the control method of this invention, each battery energy storage system no longer responds to local information in isolation, but rather conducts organized charging and discharging behavior under a unified coordination mechanism based on global or regional optimization goals. During peak load periods or periods of insufficient local power generation, the battery energy storage system discharges in a timely manner to supplement the power deficit; during off-peak periods or periods of high renewable energy generation, the battery energy storage system switches to charging mode to absorb excess energy, thereby achieving power balance and energy time shift between power distribution areas and the system as a whole. Through this cross-power distribution area collaborative charging and discharging strategy, the battery energy storage system not only smooths the net load fluctuations of each power distribution area, but also significantly improves the overall operational stability and economy of the multi-power distribution area system through power mutual assistance and time complementarity between power distribution areas. This invention enables the efficient utilization of heterogeneous energy storage resources, jointly supporting system voltage stability, suppressing power fluctuations, and enhancing the ability to absorb renewable energy fluctuations. Through continuous charging and discharging behavior, stable operation of the multi-power distribution area system is achieved.

[0107] In a multi-regional interconnected power system with coordinated frequency regulation, the output power variation of electric vehicles is as follows: Figure 9 As shown in the diagram, under the control method of this invention, electric vehicles within a multi-station system participate in system frequency regulation via V2G technology. Through electric vehicle aggregators or centralized charging stations, dispersed electric vehicles participate in the frequency regulation of the multi-station system in an aggregated manner. Simulation results show that electric vehicles within the station participate in the system's frequency regulation, ultimately reaching a stable state.

[0108] This invention relates to a control system designed for the power supply area of ​​distribution transformers (i.e., "transformer substations"). It aims to achieve flexible energy sharing and efficient energy management within and between adjacent transformer substations through distributed energy resources, substation energy storage devices, and intelligent control technology. In modern smart grids, coordinated control among multiple distribution transformer substations is crucial. Each substation has unique load characteristics and power generation capacity; independent control may lead to resource waste or system instability. Therefore, multi-substation coordinated control strategies are of great significance for improving the efficiency and stability of the entire power grid.

[0109] For multi-station interconnection systems of photovoltaics, energy storage, and electric vehicles, appropriate control schemes are needed to realize resource exchange between systems and ensure the stable operation of the entire system.

[0110] Power balancing across multiple distribution substations is a key means of achieving efficient mutual assistance of power resources between regions. It addresses localized supply-demand imbalances by dynamically adjusting power flow between each substation and the main grid or adjacent substations. Its significance lies in improving the overall operating efficiency of the power grid, reducing equipment losses, voltage fluctuations, and outage risks caused by overload or underload in individual substations, while simultaneously promoting the integration of distributed energy sources (such as photovoltaic and wind power) and enhancing the flexibility and reliability of the distribution network. The core objective of power balancing is to achieve load equilibrium between substations by optimizing power allocation and avoiding resource waste. Specifically, this includes reducing grid transmission losses, delaying equipment expansion investment, improving power quality, and supporting rapid power compensation during fault or islanded operation to ensure system stability. The ultimate goal is to build a resilient distribution network that can adapt to the needs of high-proportion renewable energy integration and complex load changes.

[0111] Frequency balancing in multi-distribution area interconnected systems is fundamental to maintaining stable regional power grid operation. It coordinates the generation units, battery storage systems, and other equipment in each distribution area to ensure the interconnected system frequency remains near its rated value (e.g., 50Hz). Its core significance lies in two aspects: firstly, it effectively suppresses frequency deviations caused by distributed power output fluctuations, sudden load changes, or other reasons, preventing cascading failures such as generator disconnection and protection malfunctions; secondly, it enhances the inertia support capacity of the interconnected system. Through the coordinated participation of multiple distribution areas in primary frequency regulation, it significantly strengthens the grid's adaptability to high-proportion renewable energy penetration, providing key technical support for building a new power system dominated by renewable energy. Especially in extreme weather or main grid failure situations, interconnected distribution areas can achieve stable islanded operation through rapid frequency adjustment, significantly improving the power supply reliability of critical loads.

[0112] The fundamental purpose of frequency balancing in multi-distribution area systems is to establish a multi-timescale collaborative control system to achieve safe and economical operation of the distribution network. Technically, a unified frequency coordination control strategy is needed to enable the battery storage systems, adjustable loads, and distributed power sources in each distribution area to work together to control frequency deviation within the standard range of ±0.2Hz. Operationally, frequency regulation resources in each distribution area need to be optimized to reduce the frequency regulation pressure on individual areas. At the system architecture level, a robust communication network needs to be built to ensure that frequency regulation commands are executed within a short timeframe. The ultimate goal is to form an adaptive frequency coordination control mechanism for distribution areas that meets power quality requirements during normal operation while also addressing the frequency stability challenges posed by the randomness of new energy generation and load shocks, providing crucial support for the construction of smart distribution networks.

[0113] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A coordinated frequency regulation system for a multi-distribution power system, wherein the multi-distribution power system comprises at least two distribution areas connected by a tie line; each distribution area comprises: Traditional generator sets, battery energy storage systems, and electric vehicle clusters connected via aggregators; The characteristic feature is that the coordinated frequency adjustment system includes a controller configured to: The regional control error of each transformer area is obtained based on the power deviation of the inter-transformer tie lines and the frequency deviation of each transformer area. Obtain the status of each transformer area and construct a memory output signal based on the historical data of the transformer area status; Based on the regional control error, the memory output signal, and the station state, the equivalent control signal is obtained by using a preset sliding surface function and solving according to sliding mode control theory. Based on the equivalent control signal and the preset participation weights, control commands are generated and issued for the traditional generator set, the electric vehicle cluster, and the battery energy storage system to coordinately adjust the frequency of the multi-area interconnected power system.

2. The multi-regional interconnected power system coordinated frequency regulation system according to claim 1, characterized in that, The formula for obtaining the regional control error is as follows: in, For the station area index, For the current time, For the first Regional control error of each transformer area For the first Inter-regional interconnection line power deviation in each transformer area This is the frequency deviation coefficient. For the first Frequency deviation of each station area; The formula for obtaining the memory output signal is as follows: in, For the first The memory output signal of each station area The size of the historical data , For the first The output parameter matrix of each transformer area For the first The status of each station area.

3. The multi-regional interconnected power system coordinated frequency regulation system according to claim 2, characterized in that, The status of the transformer substation includes at least the mechanical output power deviation of the conventional generator set, the governor position deviation of the conventional generator set, the power deviation of the tie line, the frequency deviation of each transformer substation, the aggregated output power of the electric vehicle cluster, and the output power of the battery energy storage system.

4. The multi-regional interconnected power system coordinated frequency regulation system according to claim 1, characterized in that, The specific sliding surface function is as follows: in, For the first Sliding surface function of each platform area For the first The sliding surface parameter vectors for each platform area are selected to ensure... It is neither strange nor unusual. For the first The status of each transformer station area For the first The transformer state parameter matrix of each transformer area For integration variables The corresponding number The status of each transformer station area For the current time, The size of the historical data For the first Control signal parameter matrix for each transformer area For the first Controller gain for each station area For the first The integral value of the area control error of each transformer station area; The expression for the equivalent control signal is as follows: in, This is the equivalent sliding mode control signal. For the first External interference in individual transformer areas For the first The output parameter matrix of each transformer area For the first Historical averages or estimates of the status of each transformer substation.

5. The multi-station interconnected power system coordinated frequency regulation system according to claim 4, characterized in that, The dynamic relationship between the transformer area state, transformer area state parameter matrix, transformer area output parameter matrix, and integral value of the area control error is defined by the following system state-space equation and system state dynamic equation: The system state-space equation is: in, For the first The derivative of the state of each transformer area. For the first The state parameter matrix of each station area For the first The status of each transformer station area For the first Control signal parameter matrix for each transformer area For the first Interference coefficient matrix of each station area For system output, For the first The output parameter matrix of each transformer area For the first External interference in each station area For the first Controller gain for each station area For the first Historical average or estimated value of the status of each transformer area For the first The equivalent perturbation matrix of each station area For the first The status of each transformer station area For the first The sliding surface parameter vectors for each platform area are selected to ensure... It is neither right nor wrong; The dynamic equations of the system state are as follows: in, For the first The differential mechanical output power deviation of each transformer area For the first Differential power deviation of inter-regional interconnection lines in each transformer area For the first The differential frequency deviation of each station area For the first The differential position deviation of the speed controller in each distribution zone For the first The differential output power of electric vehicles in each power station area The derivative of the output power of the battery energy storage system. For the first Mechanical output power deviation in each station area For the first Speed ​​controller position deviation in each station area For the first The time constant of the turbine / steam turbine in each distribution area For the first Inter-regional interconnection line power deviation in each transformer area For the first The first and second districts Inter-regional synchronization coefficient of each station area For the first Frequency deviation of each station area For adjacent Frequency deviation of each station area For the first The generator inertia constant of each transformer substation area For the first The damping coefficient of the generator in each distribution area For the first Load deviation of each transformer area For the first The renewable energy output power of each substation area For the first The sagging coefficient of each platform area For the first The time constant of the speed controller in each distribution zone For the first The ACE points for each region The participation ratio of traditional generator sets. For the first Control signals for each transformer area For the first The output power of electric vehicles in each power station area This represents the participation rate coefficient for electric vehicles. For the first Electric vehicle control coefficients for each district For the first The time constant of electric vehicles in each station area For the output power of the battery energy storage system, The participation ratio of battery energy storage systems. For the control coefficient of the battery energy storage system, This represents the time constant of the battery energy storage system.

6. The multi-regional interconnected power system coordinated frequency regulation system according to claim 5, characterized in that, The external disturbances or load deviations in the system state-space equations include the power output of the photovoltaic power generation unit, and the formula for obtaining the power output of the photovoltaic power generation unit is as follows: in, For the first Power output of photovoltaic power generation units in each substation area For the gain of photovoltaic power generation units, It is a time constant. For the Laplace operator, For the first Solar irradiance intensity of each station area.

7. The multi-regional interconnected power system coordinated frequency regulation system according to claim 1, characterized in that, The controller generates and issues control commands to the traditional generator set, the electric vehicle cluster, and the battery energy storage system based on the equivalent control signal and preset participation weights. The controller is further configured to adaptively select the controller gain of the battery energy storage system based on the interval where the frequency deviation of the distribution area is located after the battery energy storage system receives the control command, as detailed below: When the frequency deviation of the substation is greater than the positive threshold of the dead zone of the response frequency change, the controller gain of the battery energy storage system is greater than zero, and the battery energy storage system is in a discharging state. When the frequency deviation of the substation is greater than or equal to the negative threshold of the dead zone of the response frequency change and less than or equal to the positive threshold of the dead zone of the response frequency change, the controller gain of the battery energy storage system is equal to zero, and the battery energy storage system stops charging and discharging. When the frequency deviation of the substation area is less than the negative threshold of the dead zone of the response frequency change, the controller gain of the battery energy storage system is less than zero, and the battery energy storage system is in a charging state. The formula for obtaining the controller gain of the battery energy storage system is as follows: in, For the controller gain of the battery energy storage system, For discharge control gain, To control the charging gain, For the desired charging power ratio, For the desired discharge power ratio, A positive threshold for responding to frequency changes. The negative threshold for responding to frequency changes, The positive threshold for the dead zone in response to frequency changes, The negative threshold for the dead zone in response to frequency changes.

8. The multi-regional interconnected power system coordinated frequency regulation system according to claim 7, characterized in that, The controller is also configured to monitor and manage the state of charge of the battery energy storage system when generating control commands for the battery energy storage system. The formula for obtaining the state of charge of the battery energy storage system is as follows: in, For the working performance of battery energy storage systems, Represents the initial value of the state of charge. Indicates the storage capacity of energy storage. The output power of the battery energy storage system. This refers to the output voltage of the battery energy storage system. This is the output current of the battery energy storage system.

9. The multi-regional interconnected power system coordinated frequency regulation system according to claim 1, characterized in that, The participation weights include: participation weights for traditional generator sets, electric vehicles, and battery energy storage systems. The participation weights for traditional generator sets, electric vehicles, and battery energy storage systems satisfy the following relationship: in, For traditional generator sets to participate in the weighting, For electric vehicles to participate in the weighting, Weighting is assigned to battery energy storage systems.

10. A method for coordinated frequency regulation in a multi-region interconnected power system, characterized in that, The method, applied to the multi-area interconnected power system coordinated frequency regulation system according to any one of claims 1 to 9, comprises: S1, obtain the power deviation of the inter-station tie line and the frequency deviation of each station area; S2, obtain the area control error of each substation based on the power deviation of the inter-substation tie line and the frequency deviation of each substation; S3, acquire the status of each transformer area, and construct a memory output signal based on the historical data of the transformer area status; S4. Based on the regional control error, the memory output signal, and the station state, the equivalent control signal is obtained by using a preset sliding surface function and solving according to sliding mode control theory. S5. Based on the equivalent control signal and the preset participation weight, generate and issue control commands for the traditional generator set, the electric vehicle cluster and the battery energy storage system to coordinately adjust the frequency of the multi-area interconnected power system.

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