Light storage system regulation and control method and system considering economical efficiency and small signal stability

Abstract

The invention discloses an optical storage system regulation and control method and system considering economical efficiency and small signal stability, mainly relates to the technical field of optical storage system regulation and control, and aims to solve the problem that an existing scheme lacks an optical storage system primary frequency modulation capacity configuration scheme considering both operation economical efficiency and power grid stability. Comprising the steps of obtaining a preset primary frequency modulation total cost minimum formula and a preset constraint condition, and further obtaining the minimum primary frequency modulation total cost which is full of the preset constraint condition; obtaining the active power of the photovoltaic power station under the lowest primary frequency modulation total cost, and constructing a stable domain variable parameter vector; and on the basis of a preset stability constraint condition and a preset target function containing the frequency modulation parameter, obtaining a specific value of the preset frequency modulation parameter in the preset target function meeting the preset stability constraint condition.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic storage system control, and in particular to a photovoltaic storage system control method and system that considers both economy and small-signal stability. Background Art

[0002] As the penetration rate of renewable energy power generation equipment continues to increase, the replacement of traditional synchronous generators with wind and photovoltaic power generation has become an inevitable trend in the development of the renewable energy industry. However, this poses new challenges to system frequency security and stability. When building new power systems, both national renewable energy grid connection guidelines and the latest national standards require renewable energy stations to participate in the system's primary frequency regulation, providing inertia support, etc. However, renewable energy power generation equipment is connected to the grid via a converter. Due to the phase-locked loop (PLL) system, grid-following converters exhibit weak inertia in response to grid dynamics and lack the ability to adjust upward frequency. Therefore, the converter control strategy must be adjusted to mimic the static frequency characteristic curve of the synchronous generator.

[0003] Currently, methods for photovoltaic and other renewable energy units to participate in grid frequency regulation include combined photovoltaic and energy storage response and load shedding droop control, often achieved through setting control parameters. However, existing research is limited to single units or single stations, failing to consider the differences in capacity and output limits across different equipment operating conditions, leading to complex frequency regulation calculations. Furthermore, renewable energy stations participating in frequency regulation must operate at reduced load, resulting in economic losses. When applied to renewable energy clusters, traditional single-unit frequency regulation strategies fail to fully utilize the frequency regulation power capacity, leading to power curtailment.

[0004] New energy storage systems offer diverse service capabilities and are a key enabler of new power systems. Existing research focuses on power allocation strategies and capacity optimization, but the primary frequency regulation configuration and operating model for renewable energy combined with shared energy storage remain unclear, making it difficult for PV cluster control mechanisms to adapt to the demands of coordinated operation. Specifically, there is a lack of primary frequency regulation capacity configuration solutions and adaptive operating models for PV-storage systems that balance economic efficiency and grid friendliness. Existing solutions fail to consider small-signal stability in primary frequency regulation scenarios, effectively failing to leverage the advantages of energy storage. Summary of the Invention

[0005] The present application provides a photovoltaic storage system control method and system that considers economy and small signal stability, so as to solve the problem that the existing solutions lack a photovoltaic storage system primary frequency regulation capacity configuration solution that takes into account both operation economy and grid stability.

[0006] In a first aspect, the present application provides a method for controlling a photovoltaic storage system taking into account both economy and small-signal stability, the method comprising: Obtain the preset minimum total primary frequency regulation cost formula and preset constraints, and then obtain the minimum total primary frequency regulation cost that satisfies all preset constraints; wherein the preset constraints include at least: small signal stability constraints of the photovoltaic system, primary frequency regulation power constraints, energy storage system power and state constraints, energy storage system SOC constraints, energy storage operation constraints, and random planning constraints; Obtain the active power of the photovoltaic power station under the lowest total cost of primary frequency regulation, and then construct the variable parameter vector in the stability domain; Based on the preset stability constraints and the preset objective function including the frequency modulation parameters, the specific values ​​of the preset frequency modulation parameters in the preset objective function including the frequency modulation parameters that meet the preset stability constraints are obtained; wherein, the preset stability constraints include: the frequency modulation stability domain constraints of the photovoltaic power station including the stability domain variable parameter vector and the single frequency modulation time constraints.

[0007] In one implementation of the present application, the preset formula for the lowest total cost of a frequency modulation operation specifically includes: Get the formula for the lowest total cost of preset primary frequency modulation: , calculate and obtain the lowest total cost F of primary frequency regulation; in, represents the reserve cost of the PV cluster participating in primary frequency regulation, represents the investment, construction, and operation and maintenance costs of shared energy storage. represents the energy storage charging and discharging cost; and , , ; in, represents the photovoltaic grid-connected electricity price, represents the photovoltaic sampling time interval, represents the total number of photovoltaic power stations, Indicates the theoretical power reserve retained when the PV cluster is operating at load shedding. Indicates the duration of one frequency modulation. Indicates the frequency reduction value, Indicates the frequency regulation auxiliary compensation electricity price; Indicates the power demand allocated by the photovoltaic system during a frequency regulation process; and

[0008] ， ， ， in, Indicates the annual interest rate conversion coefficient of energy storage ， Indicates annual interest rate ， Indicates energy storage life， Indicates the energy storage operation and maintenance cost coefficient ， Indicates the annual unit power cost of energy storage ， Indicates the average annual power of energy storage ， represents the rated capacity cost of energy storage, Indicates the rated capacity of energy storage; represents the annual unit power cost of energy storage; and ； in, Indicates the duration of one frequency modulation. Indicates the time of the charge and discharge process, represents the electricity purchase price in the power grid, It represents the electric power purchased from the grid when maintaining its own SOC balance at time t, Indicates the purchase and sale of electricity in the power grid, It represents the electric power sold to the grid when maintaining its own SOC balance at time t.

[0009] In one implementation of the present application, the preset constraints specifically include: The small signal stability constraint of the photovoltaic system is: ; in, represents the active power of the PV cluster at time t, Indicates the stable power output limit of the PV cluster; The primary frequency modulation power constraint is: ; in, represents the upward frequency at time t, It represents the power retained by the load-reduced operation of the ith PV power station at time t during the frequency increase process. A 0-1 decision variable representing the upward frequency regulation state of the photovoltaic cluster at time t, represents the down-regulation frequency at time t, It represents the power retained by the ith PV power station during load reduction during frequency reduction at time t. A 0-1 decision variable representing the downward frequency regulation state of the photovoltaic cluster at time t, Indicates the current frequency of the power grid, Indicates the upper boundary of the frequency regulation dead zone of the photovoltaic cluster, Indicates the lower boundary of the frequency regulation dead zone of the photovoltaic cluster; The power and state constraints of the energy storage system are: ; in, represents the lower bound of SOC when the energy storage system is operating safely, represents the SOC of the energy storage system, It represents the upper bound of SOC when the energy storage system is operating safely; The SOC constraint of the energy storage system is: ; in, represents the SOC of the energy storage system at the next moment t, represents the SOC of the energy storage system at time t, represents the operating power of the energy storage system at time t when the frequency is increased, express, represents the discharge loss coefficient, represents the capacity of the energy storage system, represents the charging loss coefficient, represents the operating power of the energy storage system at time t when the frequency is reduced; The energy storage operation constraints are: ; in, ; Indicates the rated operating power of the photovoltaic power station. Indicates the rated frequency, represents the power demand retained when the i-th PV power station in the PV cluster is operating at load shedding at time t, Indicates frequency control gain; The planning constraints are then: ; ; in, Indicates the confidence level that the spare capacity can meet the primary frequency regulation demand during the disturbance. It indicates the confidence level that the spare capacity can meet the primary frequency regulation demand during the disturbance. The power retained during load shedding during the frequency increase at time t, Indicates the power retained during load shedding during frequency reduction at time t. represents the operating power of the energy storage system when the frequency is increased at time t, represents the operating power of the energy storage system when the frequency is reduced at time t, represents the total frequency modulation power at time t, It represents the total frequency modulation power at time t.

[0010] In one implementation of the present application, constructing a stable domain variable parameter vector specifically includes: By formula: , construct a stable domain variable parameter vector ; in, Indicates the i Active power of a photovoltaic power station; Indicates the total number of PV power plants.

[0011] In one implementation of the present application, the preset stability constraints specifically include: Stability domain constraints of photovoltaic power station frequency regulation with variable stability domain parameter vector: ; in, Represents the stable domain variable parameter vector The maximum real part of the corresponding node admittance matrix characteristic root, represents the stable domain variable parameter vector; Time constraints for a frequency modulation: ; ; in, Indicates the longest adjustment time and load reduction rate among all photovoltaic power stations Photovoltaic cluster i The steady-state operating power of a photovoltaic power station before frequency regulation, Indicates the rated operating power of the photovoltaic power station. Indicates the i The gain coefficient of a photovoltaic power station, Indicates the frequency change value during a frequency modulation process. Indicates the i The power demand retained during load shedding operation of a PV power station.

[0012] In one implementation of the present application, a frequency modulation parameter preset objective function is included, specifically including: ; in, represents the first weight coefficient of the objective function, represents the second weight coefficient of the objective function, Indicates the longest adjustment time among all PV power plants, and , Indicates the i The adjustment time of a photovoltaic power station participating in a frequency regulation process, and , Indicates the i The left frequency modulation gain coefficient of a photovoltaic power station, Indicates the i The right frequency modulation gain coefficient of a photovoltaic power station, Represents the preset adjustment time calculation function; , Indicates the i The eigenvalue of the impedance ratio matrix of each photovoltaic power station, represents the impedance ratio matrix, represents the stable domain variable parameter vector, represents the Laplace operator, represents the stability margin, Indicates the angular frequency.

[0013] In a second aspect, the present application provides a control system for a photovoltaic storage system that takes into account both economy and small-signal stability. The system includes: The upper-level optimization module is used to obtain the preset minimum total primary frequency regulation cost formula and preset constraints, and then obtain the minimum total primary frequency regulation cost that satisfies all preset constraints. The preset constraints include at least: small-signal stability constraints of the photovoltaic system, primary frequency regulation power constraints, energy storage system power and state constraints, energy storage system SOC constraints, energy storage operation constraints, and random planning constraints. A construction module is used to obtain the active power of the photovoltaic power station under the lowest total cost of primary frequency regulation, and then construct a variable parameter vector in the stability domain; The lower-level optimization module is used to obtain the specific values ​​of the preset frequency modulation parameters in the preset objective function containing the frequency modulation parameters that meet the preset stability constraints based on the preset stability constraints and the preset objective function containing the frequency modulation parameters; wherein the preset stability constraints include: the frequency modulation stability domain constraints of the photovoltaic power station containing the stability domain variable parameter vector and the single frequency modulation time constraints.

[0014] In one implementation of the present application, the upper-layer optimization module includes a formula acquisition unit, which is used to obtain a preset formula for the lowest total cost of primary frequency modulation: , calculate and obtain the lowest total cost F of primary frequency regulation; in, represents the reserve cost of the PV cluster participating in primary frequency regulation, represents the investment, construction, and operation and maintenance costs of shared energy storage. Represents the energy storage charging and discharging cost; and , , ; in, represents the photovoltaic grid-connected electricity price, represents the photovoltaic sampling time interval, Represents the total number of photovoltaic power stations, Indicates the theoretical power reserve retained when the PV cluster is operating at load shedding. Indicates the duration of one frequency modulation. Indicates the frequency reduction value, Indicates the frequency regulation auxiliary compensation electricity price; Indicates the power demand allocated by the photovoltaic system during a frequency regulation process; and

[0015] ， ， ， in, represents the annual interest rate conversion coefficient of energy storage, represents the annual interest rate, Indicates energy storage life, represents the energy storage operation and maintenance cost coefficient, represents the annual unit power cost of energy storage, represents the average annual power of energy storage, represents the rated capacity cost of energy storage, Indicates the rated capacity of energy storage; represents the annual unit power cost of energy storage; and ； in ， Indicates the duration of one frequency modulation ， Indicates the time of the charging and discharging process ， Indicates the electricity purchase price in the power grid ， Indicates the power purchased from the grid to maintain its own SOC balance at time t ， Indicates the purchase and sale of electricity in the power grid, Indicates the electric power sold to the grid when maintaining its own SOC balance at time t 。

[0016] In one implementation of the present application, the upper optimization module includes a constraint acquisition unit for acquiring the photovoltaic power station frequency modulation stability domain constraint conditions of the stability domain variable parameter vector: ; in, Represents the stable domain variable parameter vector The maximum real part of the corresponding node admittance matrix characteristic root, represents the stable domain variable parameter vector; Time constraints for a frequency modulation: ; ; in, Indicates the longest adjustment time and load reduction rate among all photovoltaic power stations Photovoltaic cluster i The steady-state operating power of a photovoltaic power station before frequency regulation, Indicates the rated operating power of the photovoltaic power station. Indicates the i The gain coefficient of a photovoltaic power station, Indicates the frequency change value during a frequency modulation process. Indicates the i The power demand retained during load shedding operation of a PV power station.

[0017] In one implementation of the present application, the building block includes a building unit, Used by the formula: , construct a stable domain variable parameter vector ; in, Indicates the i Active power of a photovoltaic power station; Indicates the total number of PV power plants.

[0018] It can be seen from the above technical solutions that this application has the following advantages: This application provides a control method and system for a photovoltaic (PV)-storage system that considers both economic efficiency and small-signal stability. It also proposes a joint frequency regulation scheduling optimization strategy for a photovoltaic cluster and energy storage system that takes both economic efficiency and stability into account, employing a hierarchical sequential optimization approach. The upper-level optimization strategy for primary frequency regulation is a proposed power allocation optimization strategy for the PV-storage system that considers both economic efficiency and small-signal stability. The objective function is to reduce the primary frequency regulation cost of the PV-storage system (preset formula for minimizing total primary frequency regulation cost). The constraints (preset constraints) consider the grid-connected stability limit of the PV cluster. The upper-level optimization strategy yields the optimal power allocation solution for the energy storage system and the PV cluster under the current state. The power allocated to the PV cluster further serves as a prerequisite for the lower-level optimization strategy. The lower-level optimization strategy aims to further improve the dynamic performance of the PV cluster's primary frequency regulation response and enhance the grid-connected stability margin (including pre-set objective functions for frequency regulation parameters). It optimizes the primary frequency regulation parameters—the frequency regulation control gain coefficient and the load shedding ratio—to achieve redistribution of primary frequency regulation power within the PV cluster. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for the description. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a flow chart of a method for controlling a photovoltaic storage system that takes into account economy and small-signal stability, provided in an embodiment of the present application.

[0021] Figure 2 This is a schematic diagram of the internal structure of a photovoltaic storage system control system provided in an embodiment of the present application, taking into account economy and small signal stability. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] It should be understood by those skilled in the art that the embodiments described below are merely preferred embodiments of the present disclosure and do not imply that the present disclosure can only be implemented through these preferred embodiments. These preferred embodiments are merely intended to explain the technical principles of the present disclosure and are not intended to limit the scope of protection of the present disclosure. Based on the preferred embodiments provided by the present disclosure, all other embodiments obtained by those skilled in the art without creative effort should still fall within the scope of protection of the present disclosure.

[0024] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0025] The technical solutions proposed in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0026] The embodiment provides a method for controlling a photovoltaic storage system taking into account economy and small signal stability. Figure 1As shown, the method provided in the embodiment of the present application mainly includes the following steps: Step 110: Obtain a preset formula for the lowest total cost of primary frequency regulation and preset constraints, and then obtain the lowest total cost of primary frequency regulation that satisfies all preset constraints.

[0027] Among them, the preset constraints include at least: small signal stability constraints of the photovoltaic system, primary frequency regulation power constraints, energy storage system power and state constraints, energy storage system SOC constraints, energy storage operation constraints, and random planning constraints.

[0028] In some embodiments, the preset formula for minimizing the total cost of a frequency modulation operation specifically includes: Get the formula for the lowest total cost of preset primary frequency modulation: , calculate and obtain the lowest total cost F of primary frequency regulation; in, represents the reserve cost of the PV cluster participating in primary frequency regulation, represents the investment, construction, and operation and maintenance costs of shared energy storage. Represents the energy storage charging and discharging cost; and , , ; in, represents the photovoltaic grid-connected electricity price, represents the photovoltaic sampling time interval, Represents the total number of photovoltaic power stations, Indicates the theoretical power reserve retained when the PV cluster is operating at load shedding. Indicates the duration of one frequency modulation. Indicates the frequency reduction value, Indicates the frequency regulation auxiliary compensation electricity price; Indicates the power demand allocated by the photovoltaic system during a frequency regulation process; and

[0029] ， ， ， in, Indicates the annual interest rate conversion coefficient of energy storage ， Indicates annual interest rate ， Indicates energy storage life ， Indicates the energy storage operation and maintenance cost coefficient ， Indicates the annual unit power cost of energy storage ， Indicates the average annual power of energy storage ， represents the rated capacity cost of energy storage, Indicates the rated capacity of energy storage; represents the annual unit power cost of energy storage; and ； in, Indicates the duration of one frequency modulation. Indicates the time of the charge and discharge process, represents the electricity purchase price in the power grid, It represents the electric power purchased from the grid when maintaining its own SOC balance at time t, Indicates the purchase and sale of electricity in the power grid, It represents the electric power sold to the grid when maintaining its own SOC balance at time t.

[0030] This step predefines the formula for minimizing the total primary frequency regulation cost, including the reserved reserve costs of the PV cluster participating in primary frequency regulation, the investment, construction, and maintenance costs of shared energy storage, and the energy storage charging and discharging costs. This detailed cost calculation method helps the system more accurately assess frequency regulation costs, leading to more reasonable decisions.

[0031] Assume that in a PV-storage system, the reserve cost of the PV cluster, the investment, construction, and maintenance costs of the energy storage system, and the charging and discharging costs of the energy storage are X, Y, and Z, respectively. Using the formula in this method, the system can calculate the sum of these costs and formulate an optimal frequency regulation strategy accordingly. For example, at a given moment, the system might choose to reduce the number of times the energy storage system is charged and discharged to lower Z, while simultaneously adjusting the power output of the PV cluster to lower X, thereby reducing the total cost.

[0032] In some embodiments, the preset constraints specifically include: The small signal stability constraint of the photovoltaic system is: ; in, represents the active power of the PV cluster at time t, Indicates the stable power output limit of the PV cluster; The primary frequency modulation power constraint is: ; in, represents the upward frequency at time t, It represents the power retained by the load-reduced operation of the ith PV power station at time t during the frequency increase process. A 0-1 decision variable representing the upward frequency regulation state of the photovoltaic cluster at time t, represents the down-regulation frequency at time t, It represents the power retained by the ith PV power station during load reduction during frequency reduction at time t. A 0-1 decision variable representing the downward frequency regulation state of the photovoltaic cluster at time t, Indicates the current frequency of the power grid, Indicates the upper boundary of the frequency regulation dead zone of the photovoltaic cluster, Indicates the lower boundary of the frequency regulation dead zone of the photovoltaic cluster; The power and state constraints of the energy storage system are: ; in, represents the lower bound of SOC when the energy storage system is operating safely, represents the SOC of the energy storage system, It represents the upper bound of SOC when the energy storage system is operating safely; The SOC constraint of the energy storage system is: ; in, represents the SOC of the energy storage system at the next moment t, represents the SOC of the energy storage system at time t, represents the operating power of the energy storage system at time t when the frequency is increased, express, represents the discharge loss coefficient, represents the capacity of the energy storage system, represents the charging loss coefficient, represents the operating power of the energy storage system at time t when the frequency is reduced; The energy storage operation constraints are: ; in, ; Indicates the rated operating power of the photovoltaic power station. Indicates the rated frequency, represents the power demand retained when the i-th PV power station in the PV cluster is operating at load shedding at time t, Indicates frequency control gain; The planning constraints are then: ; ; in, Indicates the confidence level that the spare capacity can meet the primary frequency regulation demand during the disturbance. It indicates the confidence level that the spare capacity can meet the primary frequency regulation demand during the disturbance. The power retained during load shedding during the frequency increase at time t, Indicates the power retained during load shedding during frequency reduction at time t. represents the operating power of the energy storage system when the frequency is increased at time t, represents the operating power of the energy storage system when the frequency is reduced at time t, represents the total frequency modulation power at time t, It represents the total frequency modulation power at time t.

[0033] The specific contents of the preset constraints involved in this step include the small-signal stability constraints of the PV system, the primary frequency regulation power constraints, and the energy storage system power and state constraints. Setting these constraints helps ensure the stability and safety of the system during the frequency regulation process.

[0034] Imagine a PV-storage system experiencing frequency modulation, where the PV plant's active power exceeds its stable power output limit, or the energy storage system's SOC exceeds its safe operating range. By employing the constraints in this method, the system can promptly detect and correct these issues, preventing system instability or damage. For example, if the system detects that the PV plant's active power exceeds its stable limit at a certain moment, it will automatically adjust the power output to ensure stable system operation.

[0035] Step 120: Obtain the active power of the photovoltaic power station under the lowest total primary frequency regulation cost, and then construct a stable domain variable parameter vector.

[0036] The construction of the stable domain variable parameter vector can be specifically as follows: By formula: , construct a stable domain variable parameter vector ; in, Indicates the i Active power of a photovoltaic power station; Indicates the total number of PV power plants.

[0037] Those skilled in the art will appreciate that the present application associates the active power of the photovoltaic power station with the stability domain variable parameter vector through a formula, which helps the system to more accurately evaluate the stability during the frequency modulation process.

[0038] Assume that a photovoltaic storage system needs to evaluate its stability during frequency modulation. By using the formula in this method, the system can calculate the specific value of the variable parameter vector in the stable domain and judge whether the system is in a stable state based on it. For example, at a certain moment, if the system calculates that the value of the variable parameter vector in the stable domain is within a certain range, the system is considered to be in a stable state. Step 130: Based on the preset stability constraint condition and the preset objective function including the frequency modulation parameter, obtain a specific value of the preset frequency modulation parameter in the preset objective function that satisfies the preset stability constraint condition.

[0039] Among them, the preset stability constraint conditions include: photovoltaic power station frequency regulation stability domain constraint conditions including stability domain variable parameter vector and primary frequency regulation time constraint conditions.

[0040] In some embodiments, the preset stability constraints specifically include: Stability domain constraints of photovoltaic power station frequency regulation with variable stability domain parameter vector: ; in, Represents the stable domain variable parameter vector The maximum real part of the corresponding node admittance matrix characteristic root, represents the stable domain variable parameter vector; Time constraints for a frequency modulation: ; ; in, Indicates the longest adjustment time and load reduction rate among all photovoltaic power stations Photovoltaic cluster i The steady-state operating power of a photovoltaic power station before frequency regulation, Indicates the rated operating power of the photovoltaic power station. Indicates the i The gain coefficient of a photovoltaic power station, Indicates the frequency change value during a frequency modulation process. Indicates the i The power demand retained during load shedding operation of a PV power station.

[0041] This claim details the specific content of the preset stability constraints, including the PV power plant frequency regulation stability domain constraints and the primary frequency regulation time constraints. Setting these constraints helps the system more accurately control the stability and response speed during the frequency regulation process.

[0042] Consider a scenario where a PV-storage system needs to ensure stability and responsiveness during frequency modulation. By employing the constraints in this method, the system can monitor and adjust the frequency modulation strategy in real time to ensure that the system meets the stability domain constraints and the frequency modulation time constraints. For example, if the system detects that the frequency modulation time exceeds the limit, it will automatically adjust the frequency modulation strategy to shorten the frequency modulation time and improve the response speed.

[0043] The frequency modulation parameter preset objective function includes: ; in, represents the first weight coefficient of the objective function, represents the second weight coefficient of the objective function, Indicates the longest adjustment time among all PV power plants, and , Indicates the i The adjustment time of a photovoltaic power station participating in a frequency regulation process, and , Indicates the i The left frequency modulation gain coefficient of a photovoltaic power station, Indicates the i The right frequency modulation gain coefficient of a photovoltaic power station, Represents the preset adjustment time calculation function; , Indicates the i The eigenvalue of the impedance ratio matrix of each photovoltaic power station, represents the impedance ratio matrix, represents the stable domain variable parameter vector, represents the Laplace operator, represents the stability margin, Indicates the angular frequency.

[0044] As described above, this embodiment minimizes the total frequency regulation cost while meeting system stability requirements by obtaining a preset formula for the lowest total primary frequency regulation cost and pre-set constraints. This approach not only improves the economic efficiency of the solar-to-storage system but also ensures its stable operation, which is of great significance for improving the reliability and economic efficiency of the power grid.

[0045] Assuming a PV-storage system comprises multiple PV plants and energy storage devices, this method automatically calculates the lowest total primary frequency regulation cost while satisfying small-signal stability constraints, primary frequency regulation power constraints, and energy storage system power and state constraints. For example, at a given moment, the system calculates the optimal frequency regulation strategy based on real-time data, optimizing power allocation between PV plants and energy storage devices. This reduces frequency regulation costs while ensuring system stability.

[0046] In addition, this application Figure 2 The embodiment of the present application provides a control system for a photovoltaic storage system that takes into account economy and small signal stability. Figure 2 As shown, the system provided in the embodiment of the present application mainly includes: The upper-layer optimization module 210 is used to obtain a preset minimum formula for the total cost of primary frequency regulation and preset constraints, and then obtain the minimum total cost of primary frequency regulation that satisfies all preset constraints; wherein the preset constraints include at least: small-signal stability constraints of the photovoltaic system, primary frequency regulation power constraints, energy storage system power and state constraints, energy storage system SOC constraints, energy storage operation constraints, and random planning constraints.

[0047] The upper layer optimization module 210 includes a formula obtaining unit, which is used to obtain the preset minimum total cost formula for primary frequency modulation: , calculate and obtain the lowest total cost F of primary frequency regulation; in, represents the reserve cost of the PV cluster participating in primary frequency regulation, represents the investment, construction, and operation and maintenance costs of shared energy storage. Represents the energy storage charging and discharging cost; and , , ; in, represents the photovoltaic grid-connected electricity price, represents the photovoltaic sampling time interval, Represents the total number of photovoltaic power stations, Indicates the theoretical power reserve retained when the PV cluster is operating at load shedding. Indicates the duration of one frequency modulation. Indicates the frequency reduction value, Indicates the frequency regulation auxiliary compensation electricity price; Indicates the power demand allocated by the photovoltaic system during a frequency regulation process; and

[0048] ， ， ， in, represents the annual interest rate conversion coefficient of energy storage, represents the annual interest rate, Indicates energy storage life, represents the energy storage operation and maintenance cost coefficient, represents the annual unit power cost of energy storage, represents the average annual power of energy storage, represents the rated capacity cost of energy storage, Indicates the rated capacity of energy storage; represents the annual unit power cost of energy storage; and ； in ， Indicates the duration of one frequency modulation ， Indicates the time of the charging and discharging process ， Indicates the electricity purchase price in the power grid ， Indicates the power purchased from the grid to maintain its own SOC balance at time t ， Indicates the purchase and sale of electricity in the power grid, Indicates the electric power sold to the grid when maintaining its own SOC balance at time t 。

[0049] The upper optimization module 210 includes a constraint acquisition unit for acquiring the stability domain constraint conditions of the photovoltaic power station frequency modulation of the stability domain variable parameter vector: ; in, Represents the stable domain variable parameter vector The maximum real part of the corresponding node admittance matrix eigenvalue, represents the stable domain variable parameter vector; Time constraints for a frequency modulation: ; ; in, Indicates the longest adjustment time and load reduction rate among all photovoltaic power stations Photovoltaic cluster i The steady-state operating power of a photovoltaic power station before frequency regulation, Indicates the rated operating power of the photovoltaic power station. Indicates the i The gain coefficient of a photovoltaic power station, Indicates the frequency change value during a frequency modulation process. Indicates the i The power demand retained during load shedding operation of a PV power station.

[0050] The construction module 220 is used to obtain the active power of the photovoltaic power station under the lowest total primary frequency regulation cost, and then construct a stable domain variable parameter vector.

[0051] The building block 220 includes building units, Used by the formula: , construct a stable domain variable parameter vector ; in, Indicates the i Active power of a photovoltaic power station; Indicates the total number of PV power plants.

[0052] The lower-level optimization module 230 is used to obtain the specific values ​​of the preset frequency modulation parameters in the preset objective function that meet the preset stability constraints based on the preset stability constraints and the preset objective function including the frequency modulation parameters; wherein the preset stability constraints include: the frequency modulation stability domain constraints of the photovoltaic power station including the stability domain variable parameter vector and the one-time frequency modulation time constraints.

[0053] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for a photovoltaic storage system considering economic efficiency and small signal stability, characterized in that: The method comprises: Obtain the preset minimum total primary frequency regulation cost formula and preset constraints, and then obtain the minimum total primary frequency regulation cost that satisfies all preset constraints; wherein the preset constraints include at least: small signal stability constraints of the photovoltaic system, primary frequency regulation power constraints, energy storage system power and state constraints, energy storage system SOC constraints, energy storage operation constraints, and random planning constraints; Obtain the active power of the photovoltaic power station under the lowest total cost of primary frequency regulation, and then construct the variable parameter vector in the stability domain; Based on the preset stability constraint conditions and the preset objective function including the frequency modulation parameters, the specific values ​​of the preset frequency modulation parameters in the preset objective function that meet the preset stability constraint conditions are obtained; wherein, the preset stability constraint conditions include: the frequency modulation stability domain constraint conditions of the photovoltaic power station including the stability domain variable parameter vector and the single frequency modulation time constraint conditions.

2. The control method for a photovoltaic storage system considering economy and small signal stability according to claim 1 is characterized in that: The preset formula for the lowest total cost of primary frequency regulation specifically includes: Get the formula for the lowest total cost of preset primary frequency modulation: , calculate and obtain the lowest total cost F of primary frequency regulation; in, represents the reserve cost of the PV cluster participating in primary frequency regulation, represents the investment, construction, and operation and maintenance costs of shared energy storage. Represents the energy storage charging and discharging cost; and , ， ； in, represents the photovoltaic grid-connected electricity price, represents the photovoltaic sampling time interval, Represents the total number of photovoltaic power stations, Indicates the theoretical power reserve retained when the PV cluster is operating at load shedding. Indicates the duration of one frequency modulation. Indicates the frequency reduction value, Indicates the frequency regulation auxiliary compensation electricity price; Indicates the power demand allocated by the photovoltaic system during a frequency regulation process; and ， ， ， in, Indicates the annual interest rate conversion coefficient of energy storage ， Indicates annual interest rate ， Indicates energy storage life ， Indicates the energy storage operation and maintenance cost coefficient ， Indicates the annual unit power cost of energy storage ， Indicates the average annual power of energy storage ， represents the rated capacity cost of energy storage, Indicates the rated capacity of energy storage; represents the annual unit power cost of energy storage; and ； in, Indicates the duration of one frequency modulation. Indicates the time of the charge and discharge process, represents the electricity purchase price in the power grid, It represents the electric power purchased from the grid when maintaining its own SOC balance at time t, Indicates the purchase and sale of electricity in the power grid, It represents the electric power sold to the grid when maintaining its own SOC balance at time t.

3. The control method for a photovoltaic storage system considering economy and small signal stability according to claim 1 is characterized in that: The preset constraints include: The small signal stability constraint of the photovoltaic system is: ； in, represents the active power of the PV cluster at time t, Indicates the stable power output limit of the PV cluster; The primary frequency modulation power constraint is: ； in, represents the upward frequency at time t, It represents the power retained by the load-reduced operation of the ith PV power station at time t during the frequency increase process. A 0-1 decision variable representing the upward frequency regulation state of the photovoltaic cluster at time t, represents the down-regulation frequency at time t, It represents the power retained by the ith PV power station during load reduction during frequency reduction at time t. A 0-1 decision variable representing the downward frequency regulation state of the photovoltaic cluster at time t, Indicates the current frequency of the power grid, Indicates the upper boundary of the frequency regulation dead zone of the photovoltaic cluster, Indicates the lower boundary of the frequency regulation dead zone of the photovoltaic cluster; The power and state constraints of the energy storage system are: ； in, represents the lower bound of SOC when the energy storage system is operating safely, Represents the SOC of the energy storage system, It represents the upper bound of SOC when the energy storage system is operating safely; The SOC constraint of the energy storage system is: ； in, represents the SOC of the energy storage system at the next moment t, represents the SOC of the energy storage system at time t, represents the operating power of the energy storage system at time t when the frequency is increased, express, represents the discharge loss coefficient, represents the capacity of the energy storage system, represents the charging loss coefficient, represents the operating power of the energy storage system at time t when the frequency is reduced; The energy storage operation constraints are: ； in, ; Indicates the rated operating power of the photovoltaic power station. Indicates the rated frequency, represents the power demand retained when the i-th PV power station in the PV cluster is operating at load shedding at time t, Indicates frequency control gain; The planning constraints are then: ； ； in, Indicates the confidence level that the spare capacity can meet the primary frequency regulation demand during the disturbance. It indicates the confidence level that the spare capacity can meet the primary frequency regulation demand during the disturbance. The power retained during load shedding during the frequency increase at time t, Indicates the power retained during load shedding during frequency reduction at time t. represents the operating power of the energy storage system when the frequency is increased at time t, represents the operating power of the energy storage system when the frequency is reduced at time t, represents the total frequency modulation power at time t, It represents the total frequency modulation power at time t.

4. The control method for a photovoltaic storage system considering economy and small signal stability according to claim 1, characterized in that: Construct a stable domain variable parameter vector, specifically including: By formula: , construct a stable domain variable parameter vector ; in, Indicates the i Active power of a photovoltaic power station; Indicates the total number of PV power plants.

5. The control method for a photovoltaic storage system considering economy and small signal stability according to claim 1 is characterized in that: Preset stability constraints, including: Stability domain constraints of photovoltaic power station frequency regulation with variable stability domain parameter vector: ； in, Represents the stable domain variable parameter vector The maximum real part of the corresponding node admittance matrix characteristic root, represents the stable domain variable parameter vector; Time constraints for a frequency modulation: ； ； in, Indicates the longest adjustment time and load reduction rate among all photovoltaic power stations Photovoltaic cluster i The steady-state operating power of a photovoltaic power station before frequency regulation, Indicates the rated operating power of the photovoltaic power station. Indicates the i The gain coefficient of a photovoltaic power station, Indicates the frequency change value during a frequency modulation process. Indicates the i The power demand retained during load shedding operation of a PV power station.

6. The control method for a photovoltaic storage system considering economy and small signal stability according to claim 1, characterized in that: Contains the preset objective function of frequency modulation parameters, including: ； in, represents the first weight coefficient of the objective function, represents the second weight coefficient of the objective function, Indicates the longest adjustment time among all PV power plants, and , Indicates the i The adjustment time of a photovoltaic power station participating in a frequency regulation process, and , Indicates the i The left frequency modulation gain coefficient of a photovoltaic power station, Indicates the i The right frequency modulation gain coefficient of a photovoltaic power station, represents the preset adjustment time calculation function, and and The value range of is the preset range; , Indicates the i The eigenvalue of the impedance ratio matrix of each photovoltaic power station, represents the impedance ratio matrix, represents the stable domain variable parameter vector, represents the Laplace operator, represents the stability margin, Represents the angular frequency.

7. A solar storage system control system considering economy and small signal stability, characterized by: The system comprises: The upper-level optimization module is used to obtain the preset minimum total primary frequency regulation cost formula and preset constraints, and then obtain the minimum total primary frequency regulation cost that satisfies all preset constraints. The preset constraints include at least: small-signal stability constraints of the photovoltaic system, primary frequency regulation power constraints, energy storage system power and state constraints, energy storage system SOC constraints, energy storage operation constraints, and random planning constraints. A construction module is used to obtain the active power of the photovoltaic power station under the lowest total cost of primary frequency regulation, and then construct a variable parameter vector in the stability domain; The lower-level optimization module is used to obtain the specific values ​​of the preset frequency modulation parameters in the preset objective function that meet the preset stability constraints based on the preset stability constraints and the preset objective function containing the frequency modulation parameters; wherein the preset stability constraints include: the frequency modulation stability domain constraints of the photovoltaic power station containing the stability domain variable parameter vector and the single frequency modulation time constraints.

8. The photovoltaic storage system control system considering economy and small signal stability according to claim 7 is characterized in that: The upper-level optimization module includes a formula acquisition unit, which is used to obtain the preset minimum total cost formula for primary frequency modulation: , calculate and obtain the lowest total cost F of primary frequency regulation; in, represents the reserve cost of the PV cluster participating in primary frequency regulation, represents the investment, construction, and operation and maintenance costs of shared energy storage. Represents the energy storage charging and discharging cost; and , ， ； in, represents the photovoltaic grid-connected electricity price, represents the photovoltaic sampling time interval, Represents the total number of photovoltaic power stations, Indicates the theoretical power reserve retained when the PV cluster is operating at load shedding. Indicates the duration of one frequency modulation. Indicates the frequency reduction value, Indicates the frequency regulation auxiliary compensation electricity price; Indicates the power demand allocated by the photovoltaic system during a frequency regulation process; and ， ， ， in, represents the annual interest rate conversion coefficient of energy storage, represents the annual interest rate, Indicates energy storage life, represents the energy storage operation and maintenance cost coefficient, represents the annual unit power cost of energy storage, represents the average annual power of energy storage, represents the rated capacity cost of energy storage, Indicates the rated capacity of energy storage; represents the annual unit power cost of energy storage; and ； in ， Indicates the duration of one frequency modulation ， Indicates the time of the charging and discharging process ， Indicates the electricity purchase price in the power grid ， Indicates the power purchased from the grid to maintain its own SOC balance at time t ， Indicates the purchase and sale of electricity in the power grid, It represents the electric power sold to the grid when maintaining its own SOC balance at time t.

9. The photovoltaic storage system control system considering economy and small signal stability according to claim 7 is characterized in that: The upper optimization module includes a constraint acquisition unit, which is used to obtain the stability domain constraint conditions of the photovoltaic power station frequency regulation of the stability domain variable parameter vector: ； in, Represents the stable domain variable parameter vector The maximum real part of the corresponding node admittance matrix characteristic root, represents the stable domain variable parameter vector; Time constraints for a frequency modulation: ； ； in, Indicates the longest adjustment time and load reduction rate among all photovoltaic power stations Photovoltaic cluster i The steady-state operating power of a photovoltaic power station before frequency regulation, Indicates the rated operating power of the photovoltaic power station. Indicates the i The gain coefficient of a photovoltaic power station, Indicates the frequency change value during a frequency modulation process. Indicates the i The power demand retained during load shedding operation of a PV power station.

10. The photovoltaic storage system control system considering economy and small signal stability according to claim 7, characterized in that: The building blocks include building units, Used by the formula: , construct a stable domain variable parameter vector ; in, Indicates the i Active power of a photovoltaic power station; Indicates the total number of PV power plants.

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