Energy storage system coordination control method and system based on dual-objective optimization

Abstract

The invention discloses an energy storage system coordination control method and system based on dual-objective optimization, and relates to the technical field of frequency modulation. Comprising the following steps: accessing energy storage equipment into a unit control system and acquiring first operation data; based on the first operation data, constructing an energy storage-unit loss cost model and calculating to obtain a first operation reference value; according to the first operation reference value, establishing a frequency fluctuation and energy storage balance dual-objective optimization model; calculating an energy storage-unit output distribution proportion based on the optimization model; and controlling combined frequency modulation of the energy storage system and the unit according to the output distribution proportion. According to the method, the energy storage-unit combined loss cost model is established, so that the operation states of the energy storage system and the thermal power unit are accurately evaluated, and the charge state of the energy storage system is reasonably maintained by establishing the frequency fluctuation and energy storage balance dual-target optimization model; and dynamic optimization operation of the energy storage system and the thermal power generating unit is realized through a coordination control mechanism based on the optimal output distribution proportion.

Description

Technical Field

[0001] The present invention relates to the technical field of frequency modulation, and in particular to a method and system for coordinated control of an energy storage system based on dual-objective optimization. Background Art

[0002] As the scale of the power system continues to expand and the proportion of renewable energy power generation continues to increase, the task of power grid frequency regulation is becoming increasingly complex. As the main power source for frequency regulation, traditional thermal power units are difficult to meet the requirements of modern power systems for frequency regulation performance due to their inherent characteristics such as large mechanical inertia and slow regulation response. To address this problem, researchers have proposed a variety of optimized frequency regulation control strategies, such as adaptive control based on model prediction and intelligent control based on neural networks. However, these methods mainly optimize a single unit and fail to fully consider the synergistic effect of frequency regulation resources. At the same time, the frequent participation of existing thermal power units in frequency regulation not only increases unit wear, but also leads to an increase in coal consumption, which is contrary to the development requirements of energy conservation and emission reduction. Therefore, how to achieve economical and efficient use of frequency regulation resources while ensuring the stability of the power grid frequency has become a key issue that needs to be solved urgently.

[0003] In recent years, energy storage systems have received extensive attention in the field of power grid frequency regulation due to their advantages such as fast response speed and high regulation accuracy. At present, the research on energy storage systems participating in frequency regulation mainly focuses on the optimization of control strategies under independent operation mode, or simply uses energy storage systems as auxiliary frequency regulation devices for thermal power units. This type of method has the following shortcomings: First, the coordinated loss model of energy storage systems and thermal power units has not been established, making it difficult to achieve overall economic optimization; second, existing control strategies often take frequency control performance as a single optimization goal, ignoring the charge and discharge balance constraints of energy storage systems, which can easily lead to energy storage systems being in a non-optimal working state for a long time; third, there is a lack of effective multi-objective coordination mechanisms, making it difficult to achieve a good balance between frequency stability and economy. These problems have seriously restricted the application effect of energy storage systems in power grid frequency regulation, and it is urgent to propose a coordinated control method that can comprehensively consider the economy and stability of the system. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention is proposed.

[0005] Therefore, the problem to be solved by the present invention is how to optimize the overall economy of the system by establishing a joint loss cost model of energy storage and units; on the other hand, by constructing a dual-objective optimization model of frequency fluctuation and energy storage balance, the optimal working state of the energy storage system is maintained while ensuring the frequency regulation performance of the system; ultimately achieving the purpose of improving the frequency regulation quality and reducing operating costs.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a method for coordinated control of an energy storage system based on dual-objective optimization, which includes connecting an energy storage device to a unit control system and acquiring first operating data;

[0008] Based on the first operating data, construct an energy storage-unit loss cost model and calculate a first operating reference value;

[0009] According to the first operating reference value, a dual-objective optimization model of frequency fluctuation and energy storage balance is established;

[0010] The energy storage-unit output distribution ratio is calculated based on the optimization model;

[0011] The energy storage system and the unit are jointly frequency-regulated according to the output distribution ratio.

[0012] As a preferred solution of the energy storage system coordinated control method based on dual-objective optimization of the present invention, wherein: connecting the energy storage device to the unit control system and obtaining the first operation data includes: connecting the electric energy storage device to the unit circuit breaker and connecting it to the plant high-voltage bus in a preset access mode, and establishing a communication link with the unit control system through the main control unit;

[0013] When the control device sends a frequency modulation instruction to the unit, the unit responds in the original way. At the same time, the main control unit of the energy storage system collects the frequency modulation instruction, the output of the generator set and the output data of the energy storage device to form the first operating data. The first operating data is sampled at a preset frequency.

[0014] As a preferred solution of the energy storage system coordinated control method based on dual-objective optimization of the present invention, wherein: constructing an energy storage-unit loss cost model and calculating the first operating reference value includes: based on power fluctuation prediction data within a preset period, and taking the charging and discharging loss of the energy storage system, the battery state of charge loss and the unit power regulation loss as optimization targets, setting conditions including energy storage power limit, state of charge range and unit climbing constraint, and obtaining the system's optimal economic operating value as the first operating reference value by minimizing the loss cost.

[0015] As a preferred solution of the coordinated control method of the energy storage system based on dual-objective optimization of the present invention, establishing a dual-objective optimization model of frequency fluctuation and energy storage balance includes: taking the first operating reference value as the optimization benchmark point, constructing a frequency deviation minimization target based on the real-time fluctuation data of the system, constructing an energy storage quantity balance target according to the charge state of the energy storage system, and using a multi-objective optimization method based on the entropy weight method to coordinate and optimize the frequency control performance and energy storage balance performance.

[0016] As a preferred solution of the energy storage system coordinated control method based on dual-objective optimization of the present invention, wherein: calculating the energy storage-unit output distribution ratio based on the optimization model includes: updating the energy storage system charge state in real time, calculating the current optimization objective function, and obtaining the optimal power distribution coefficient;

[0017] Determine whether the preset cycle constraints are met. If so, use the current allocation coefficient as the optimal output allocation ratio and update the operating reference value. If not, continue to optimize and calculate the allocation coefficient at the next moment.

[0018] As a preferred solution of the energy storage system coordinated control method based on dual-objective optimization of the present invention, the loss cost minimization is achieved by the following objective function:

[0019]

[0020] Among them, S represents the total value of the combined frequency regulation loss of energy storage and units, and the smaller S is, the smaller the economic loss of the combined frequency regulation of energy storage and units in the preset time period is. T1 represents the power fluctuation time, E(b) represents the frequency regulation loss of the energy storage system at time b, which is determined by the charging and discharging power and the battery state of charge SOC, J(b) represents the frequency regulation loss of the unit at time b, d c Expressed as the energy storage power offset cost coefficient of the energy storage system, P c (b) is expressed as the charging and discharging power of the energy storage system, f c Expressed as the SOC shift cost coefficient, It is expressed as the average value of the SOC of the energy storage system during the preset cycle time. It represents the SOC that the energy storage system can maintain after the preset cycle ends, d g Expressed as the frequency regulation cost coefficient of unit power deviation, P g (b) is the power of the unit participating in the frequency regulation change at time b;

[0021] The objective function is solved, and the mean value is calculated every preset time period to finally obtain the first operating reference value.

[0022] As a preferred solution of the energy storage system coordinated control method based on dual-objective optimization of the present invention, the specific implementation of the dual-objective optimization model includes:

[0023] The frequency modulation performance function Y1 is constructed based on the system deviation coefficient and frequency deviation, the energy storage balance function Y2 is constructed based on the battery state of charge, and the optimization objective function is established:

[0024] Y=min(αY1+βY2)

[0025] Wherein, α represents the weight factor of the frequency regulation performance function, β represents the weight factor of the energy storage balance function, and α+β=1;

[0026] Update the battery state of charge SOC at the kth minute in real time;

[0027] When the optimization objective function takes the minimum value, the power allocation coefficient between the current energy storage system and the unit is obtained as the optimal compensation coefficient;

[0028] Determine whether the kth minute is greater than the preset period. If so, use the current optimal compensation coefficient as the output allocation ratio and calculate the reference value for the next period. Otherwise, calculate the optimal compensation coefficient for the k+1th minute.

[0029] In a second aspect, an embodiment of the present invention provides a coordinated control system for an energy storage system based on dual-objective optimization, which includes an energy storage state evaluation module, a joint optimization control module, and a frequency modulation execution module;

[0030] The energy storage status assessment module is used to collect unit output data, energy storage power data, and grid frequency regulation instruction data to establish an energy storage-unit joint operation status assessment model;

[0031] The joint optimization control module is used to build a dual-objective optimization model of economic loss and frequency stability based on the system operation status to generate the optimal output distribution ratio;

[0032] The frequency regulation execution module is used to monitor the energy storage-generator joint frequency regulation process, coordinate the energy storage system and the generator through the allocation ratio, and regularly update and optimize the frequency regulation control strategy.

[0033] In a third aspect, an embodiment of the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program instructions are executed by the processor, the steps of the energy storage system coordinated control method based on dual-objective optimization as in the first aspect of the present invention are implemented.

[0034] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program instructions are executed by a processor, the steps of the energy storage system coordinated control method based on dual-objective optimization as in the first aspect of the present invention are implemented.

[0035] The beneficial effects of the present invention are as follows: the energy storage system coordinated control method based on dual-objective optimization provided by the present invention realizes accurate evaluation of the operating status of the energy storage system and the thermal power unit by establishing a joint loss cost model of energy storage-unit, reduces the overall operating cost of the system, and optimizes the configuration efficiency of frequency regulation resources, effectively reducing unit wear and coal consumption; by constructing a dual-objective optimization model of frequency fluctuation and energy storage balance, on the basis of ensuring the frequency stability of the power grid, the charge state of the energy storage system is reasonably maintained, the system frequency regulation performance is improved, the service life of the energy storage equipment is extended, and the reliability and economy of the frequency regulation control are ensured; through a coordinated control mechanism based on the optimal output allocation ratio, the dynamic optimization operation of the energy storage system and the thermal power unit is realized, which not only improves the frequency regulation response speed, but also reduces the frequency fluctuation, and ensures the stable operation of the power system. The present invention has achieved significant improvement effects in frequency regulation quality, operating cost and system stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0037] Figure 1 A flow chart of a coordinated control method for an energy storage system based on dual-objective optimization; DETAILED DESCRIPTION

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0039] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0040] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0041] Example 1

[0042] Reference Figure 1, which is the first embodiment of the present invention, and provides a coordinated control method of an energy storage system based on dual-objective optimization, comprising:

[0043] S1, connecting the energy storage device to the unit control system and obtaining first operating data;

[0044] It should be noted that energy storage equipment can be electrochemical energy storage equipment or physical energy storage equipment. Electrochemical energy storage equipment such as lithium battery energy storage system is connected to the unit circuit breaker through the PCS system and connected to the DSC control system through the plant high-voltage bus; physical energy storage equipment such as flywheel energy storage system is connected to the unit circuit breaker through the inverter and connected to the DSC control system through the plant high-voltage bus. Among them, the lithium battery energy storage system includes the PCS container system, the battery container system, the high-voltage ring network cabinet container and the centralized control container; the flywheel energy storage system includes the flywheel body, the inverter system, the cooling system and the control system.

[0045] It should also be noted that the first operating data includes real-time operating data and historical operating data. Real-time operating data includes frequency modulation instruction data, real-time output data of the unit, and real-time output data of the energy storage device, which are used to reflect the current operating status of the system; historical operating data includes historical frequency modulation response data of the unit and historical output data of the energy storage device, which are used for system performance evaluation and optimization. The main control unit of the energy storage system collects this data through a one-way communication protocol. The sampling frequency can be set according to system requirements, and the typical value is millisecond sampling.

[0046] S2, based on the first operating data, constructing an energy storage-unit loss cost model and calculating a first operating reference value;

[0047] It should be noted that the energy storage-unit loss cost can include equipment loss cost and operation and maintenance loss cost. Equipment loss cost includes the energy storage system charging and discharging loss and the unit regulation energy consumption loss, which is mainly reflected in the loss during the energy conversion process; operation and maintenance loss cost includes equipment maintenance cost and overhaul cost, which reflects the equipment service life and maintenance needs.

[0048] It should also be noted that the charging and discharging losses of the energy storage system mainly come from the energy conversion efficiency of the energy storage unit and the loss of the power conversion system. The battery state of charge loss reflects the cycle life loss of the energy storage system, and the unit power regulation loss includes increased coal consumption and equipment wear. By setting reasonable power limits and ramp constraints, economic optimization can be achieved while ensuring the safe operation of the system.

[0049] S3, establishing a dual-objective optimization model of frequency fluctuation and energy storage balance according to the first operation reference value;

[0050] It should be noted that the dual-objective optimization can adopt the linear weighted method based on weight coefficients and the non-dominated sorting method based on Pareto optimality. The linear weighted method based on weight coefficients achieves multi-objective coordination by adjusting the weight factors α and β, which is suitable for situations where the correlation between objective functions is strong; the non-dominated sorting method based on Pareto optimality can obtain the Pareto solution set of multi-objective optimization, which is suitable for dealing with situations where there is a competitive relationship between objective functions.

[0051] S4, calculating the energy storage-unit output distribution ratio based on the optimization model;

[0052] It should be noted that the output distribution ratio determination method includes a dynamic distribution method based on optimization calculation and a fixed distribution method based on experience value. The dynamic distribution method dynamically adjusts the distribution ratio according to the real-time optimization results, which can better adapt to the changes in the system operation status; the fixed distribution method sets a fixed distribution ratio based on historical operation experience, which is simple to implement and has small calculation amount.

[0053] It should also be noted that in the dynamic allocation mode, the system continuously updates the energy storage status and calculates the optimization objective function, and obtains the optimal allocation ratio through iterative optimization. The fixed allocation mode determines a reasonable fixed allocation ratio based on statistical analysis of historical data, and regularly evaluates and adjusts it. The two methods can be selected and used according to the actual application scenario, or combined to take into account both effect and efficiency.

[0054] S5, controlling the energy storage system and the unit to jointly adjust the frequency according to the output distribution ratio;

[0055] It should be noted that joint frequency control can adopt centralized control strategy and distributed control strategy. Centralized control coordinates the output regulation of energy storage system and units through the central controller, which is suitable for scenarios with smaller system scale; distributed control realizes autonomous coordination of energy storage system and units through local controller, which is suitable for large-scale system application.

[0056] It should also be noted that by connecting the energy storage system to the thermal power unit and implementing coordinated control, the system performance can be significantly improved. This is mainly reflected in: in terms of frequency regulation performance, the frequency regulation response speed and accuracy are improved; in terms of economy, the coal consumption and equipment maintenance costs are reduced; in terms of reliability, the equipment wear caused by frequent unit adjustments is reduced. The control method based on dual-objective optimization achieves the coordinated optimization of economic benefits and frequency regulation performance.

[0057] Example 2

[0058] Reference Figure 1 , which is the second embodiment of the present invention, and provides a coordinated control method of an energy storage system based on dual-objective optimization, comprising:

[0059] S1, connecting the energy storage device to the unit control system and obtaining first operating data;

[0060] In an embodiment of the present application, connecting the energy storage device to the unit control system and obtaining the first operating data includes: connecting the energy storage device to the unit circuit breaker and connecting it to the plant high-voltage bus in a preset access mode, and establishing a communication link with the unit control system through the main control unit;

[0061] When the control device sends a frequency modulation instruction to the unit, the unit responds in the original way. At the same time, the main control unit of the energy storage system collects the frequency modulation instruction, the output of the generator set and the output data of the energy storage device to form the first operating data. The first operating data is sampled at a preset frequency.

[0062] It should be noted that energy storage equipment includes PCS container system, battery container system, high-voltage ring main unit container and centralized control container; the preset access method refers to adding energy storage equipment to the power plant, and connecting the energy storage equipment to the plant high-voltage bus through a circuit breaker, thereby connecting to the DSC system of the power plant unit to complete the access of the energy storage system; the DSC system is a distributed control system; the energy storage system is mainly composed of a main control unit, an energy storage cell unit, an energy storage inverter unit and a distribution unit, among which the energy storage cell unit refers to a DC power supply system, which can convert DC into AC through an energy storage inverter, and the distribution unit is used to access auxiliary frequency regulation objects and thermal power units.

[0063] It should be noted that the RTU device is a motion device installed in a power plant or substation. It is a key device in the dispatching automation, distribution automation and process automation systems. It is used to send AGC instructions to the unit and the energy storage system, and to merge the unit output with the energy storage system output and upload them to the power grid; the energy storage system main control unit refers to the main control unit in the energy storage system, which is used to collect the frequency modulation instructions sent by the control device and determine the output of the energy storage system; the communication protocol refers to one-way communication, sending by the control device and receiving by the energy storage system main control unit.

[0064] S2, based on the first operating data, constructing an energy storage-unit loss cost model and calculating a first operating reference value;

[0065] In the embodiment of the present application, constructing the energy storage-unit loss cost model and calculating the first operating reference value includes: based on the power fluctuation prediction data within a preset period, and taking the charging and discharging loss of the energy storage system, the battery state of charge loss and the unit power regulation loss as the optimization target, setting conditions including energy storage power limit, state of charge range and unit climbing constraint, and obtaining the system optimal economic operation value as the first operating reference value by minimizing the loss cost. The loss cost minimization is achieved by the following objective function:

[0066]

[0067] Among them, S represents the total value of the combined frequency regulation loss of energy storage and units, and the smaller S is, the smaller the economic loss of the combined frequency regulation of energy storage and units in the preset time period is. T1 represents the power fluctuation time, E(b) represents the frequency regulation loss of the energy storage system at time b, which is determined by the charging and discharging power and the battery state of charge SOC, J(b) represents the frequency regulation loss of the unit at time b, d c Expressed as the energy storage power offset cost coefficient of the energy storage system, P c (b) is expressed as the charging and discharging power of the energy storage system, f c Expressed as the SOC shift cost coefficient, It is expressed as the average value of the SOC of the energy storage system during the preset cycle time. It represents the SOC that the energy storage system can maintain after the preset cycle ends, d g Expressed as the frequency regulation cost coefficient of unit power deviation, P g (b) is the power of the unit participating in the frequency regulation change at time b;

[0068] The objective function is solved, and the mean value is calculated every preset time period to finally obtain the first operation reference value. The first operation reference value refers to the economic operation value of the energy storage-unit combined frequency regulation system.

[0069] It should be noted that the first operating data is obtained from the grid AGC dispatching instructions, the real-time output of the generator set, and the output feedback data of the energy storage device. The AGC instructions are used to control the output power of the unit and the energy storage system; the energy storage-unit joint frequency regulation optimization strategy is an implementation plan established with the purpose of minimizing frequency fluctuations and interconnection line deviations and optimizing the energy storage system's power balance; the optimal output allocation ratio refers to the output power allocation ratio of the unit and the energy storage system that satisfies the minimum frequency fluctuations and interconnection line deviations and the optimal energy storage system's power balance.

[0070] The preset time period refers to the period of time during which frequency regulation is performed according to the preset frequency regulation times; the fluctuation prediction data refers to the power prediction fluctuation data corresponding to the frequency regulation time period; the energy storage-unit joint frequency regulation system refers to the energy storage system connected to the unit DSC, which serves as a frequency regulation auxiliary resource to assist thermal power units in frequency control; the preset time period is set in advance; the first operating reference value refers to the economic operating value of the energy storage-unit joint frequency regulation system, and the solution value of the objective function is calculated once every preset time period to obtain the average value.

[0071] It should also be noted that the frequency deviation minimization goal is to improve the system frequency regulation performance, and the energy storage power balance goal ensures the sustainable operation of the energy storage system. Through the entropy weight method for multi-objective optimization, the weight of each goal can be objectively determined to achieve the optimal coordination of frequency control and energy storage balance. The system deviation coefficient reflects the measurement error of the energy storage-unit combined frequency regulation system, and the frequency deviation represents the frequency control accuracy of the system.

[0072] S3, establishing a dual-objective optimization model of frequency fluctuation and energy storage balance according to the first operating reference value;

[0073] In an embodiment of the present application, establishing a dual-objective optimization model of frequency fluctuation and energy storage balance includes: taking the first operating reference value as the optimization benchmark point, constructing a frequency deviation minimization target based on the real-time fluctuation data of the system, constructing an energy storage quantity balance target according to the charge state of the energy storage system, and using a multi-objective optimization method based on the entropy weight method to coordinate and optimize the frequency control performance and energy storage balance performance.

[0074] Furthermore, the specific implementation of the dual-objective optimization model includes:

[0075] The frequency modulation performance function Y1 is constructed based on the system deviation coefficient and frequency deviation, the energy storage balance function Y2 is constructed based on the battery state of charge, and the optimization objective function is established:

[0076] Y=min(αY1+βY2)

[0077] Wherein, α represents the weight factor of the frequency regulation performance function, β represents the weight factor of the energy storage balance function, and α+β=1;

[0078] Update the battery state of charge SOC at the kth minute in real time;

[0079] When the optimization objective function takes the minimum value, the power allocation coefficient between the current energy storage system and the unit is obtained as the optimal compensation coefficient;

[0080] Determine whether the kth minute is greater than the preset period. If so, use the current optimal compensation coefficient as the output allocation ratio and calculate the reference value for the next period. Otherwise, calculate the optimal compensation coefficient for the k+1th minute.

[0081] It should be noted that the frequency deviation minimization goal is to improve the system frequency regulation performance, and the energy storage power balance goal is to ensure the sustainable operation of the energy storage system. Through the entropy weight method for multi-objective optimization, the weight of each goal can be objectively determined to achieve the optimal coordination of frequency control and energy storage balance. The system deviation coefficient reflects the measurement error of the energy storage-unit combined frequency regulation system, and the frequency deviation represents the frequency control accuracy of the system.

[0082] S4, calculate the energy storage-unit output distribution ratio based on the optimization model;

[0083] In the embodiment of the present application, calculating the energy storage-unit output distribution ratio based on the optimization model includes: updating the energy storage system charge state in real time, calculating the current optimization objective function, and obtaining the optimal power distribution coefficient;

[0084] Determine whether the preset cycle constraints are met. If so, use the current allocation coefficient as the optimal output allocation ratio and update the operating reference value. If not, continue to optimize and calculate the allocation coefficient at the next moment.

[0085] It should be noted that the battery state of charge SOC of the kth minute is updated in real time. When the optimization objective function takes the minimum value, the power distribution coefficient of the current energy storage system and the unit is obtained as the optimal compensation coefficient, and it is determined whether the kth minute is greater than the preset cycle. If so, the current optimal compensation coefficient is used as the output distribution ratio and the reference value for the next cycle is calculated. Otherwise, the optimal compensation coefficient for the k+1th minute is calculated.

[0086] It should also be noted that the optimal compensation coefficient is used to describe the optimal power ratio of the energy storage system and the unit. By updating the state of the energy storage system in real time and dynamically calculating the optimization objective function, changes in the system operating state can be adapted. The judgment of the preset periodic constraints ensures the periodic update of the optimization process, which is conducive to maintaining the stable operation of the system.

[0087] S5, controlling the energy storage system and the unit's joint frequency regulation according to the output distribution ratio;

[0088] It should be noted that the specific implementation of controlling the joint frequency regulation of the energy storage system and the unit includes: the energy storage status assessment module is used to collect the unit output data, energy storage power data, and grid frequency regulation instruction data, and establish an energy storage-unit joint operation status assessment model; the joint optimization control module is used to build a dual-objective optimization model of economic loss and frequency stability based on the system operation status, and generate the optimal output allocation ratio; the frequency regulation execution module is used to monitor the energy storage-unit joint frequency regulation process, coordinate the energy storage system and the unit through the allocation ratio, and regularly update and optimize the frequency regulation control strategy.

[0089] It should also be noted that the optimal output distribution ratio generated by the joint optimization control module is used to guide the coordinated control of the energy storage system and the unit. The frequency regulation execution module ensures the effectiveness of the control strategy through real-time monitoring and regular updates. The system operation status evaluation provides basic data support for optimization control.

[0090] It should also be noted that by connecting the energy storage system to the thermal power unit and implementing coordinated control, the unit's frequency regulation performance indicators can be significantly improved, the frequency regulation benefits can be increased, and the cost of power generation plan assessment can be reduced. At the same time, the increase in coal consumption and equipment wear caused by frequent output adjustments of the unit can be reduced, effectively reducing the unit's operating and maintenance costs. The control method based on dual-objective optimization can achieve a comprehensive balance between economy and frequency regulation performance.

[0091] Furthermore, this embodiment also provides a coordinated control system for an energy storage system based on dual-objective optimization, including an energy storage state evaluation module, a joint optimization control module, and a frequency regulation execution module;

[0092] The energy storage status assessment module is used to collect unit output data, energy storage power data, and grid frequency regulation instruction data to establish an energy storage-unit joint operation status assessment model;

[0093] The joint optimization control module is used to build a dual-objective optimization model of economic loss and frequency stability based on the system operation status to generate the optimal output distribution ratio;

[0094] The frequency regulation execution module is used to monitor the energy storage-generator joint frequency regulation process, coordinate the energy storage system and the generator through the allocation ratio, and regularly update and optimize the frequency regulation control strategy.

[0095] This embodiment also provides a computer device, which is suitable for the case of a coordinated control method of an energy storage system based on dual-objective optimization, and includes a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute computer-executable instructions to implement the coordinated control method of an energy storage system based on dual-objective optimization as proposed in the above embodiment.

[0096] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0097] This embodiment further provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the energy storage system coordinated control method based on dual-objective optimization as proposed in the above embodiment.

[0098] In summary, the energy storage system coordinated control method based on dual-objective optimization provided by the present invention realizes the accurate evaluation of the operating status of the energy storage system and the thermal power unit by establishing a joint loss cost model of energy storage-unit, reduces the overall operating cost of the system, optimizes the configuration efficiency of frequency regulation resources, and effectively reduces unit wear and coal consumption; by constructing a dual-objective optimization model of frequency fluctuation and energy storage balance, on the basis of ensuring the stability of power grid frequency, the charge state of the energy storage system is reasonably maintained, the system frequency regulation performance is improved, the service life of the energy storage equipment is extended, and the reliability and economy of the frequency regulation control are ensured; through the coordinated control mechanism based on the optimal output allocation ratio, the dynamic optimization operation of the energy storage system and the thermal power unit is realized, which not only improves the frequency regulation response speed, but also reduces the frequency fluctuation, and ensures the stable operation of the power system. The present invention has achieved significant improvement effects in frequency regulation quality, operating cost and system stability.

[0099] Example 3

[0100] This is the third embodiment of the present invention. This embodiment provides a coordinated control method for an energy storage system based on dual-objective optimization. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0101] In order to verify the effectiveness of the energy storage system coordinated control method based on dual-objective optimization proposed in this invention, a 300MW thermal power unit was selected for experiment. The unit is equipped with a 40MW / 80MWh lithium battery energy storage system, which is connected to the unit DSC system through a 35kV bus. The energy storage system adopts a containerized design, including 20 2MW / 4MWh energy storage units, each equipped with an independent PCS system and BMS system. The test process is as follows:

[0102] First, the energy storage system is connected to the unit control system according to the design plan. A vacuum circuit breaker is used as the main disconnecting device on the high-voltage side, and a complete relay protection device is configured. The communication between the energy storage system main control unit and the unit DSC system is realized through industrial Ethernet. The communication protocol adopts IEC 60870-5-104, and the sampling period is set to 100ms. The original AGC control loop of the unit remains unchanged, and the energy storage system is connected as a frequency regulation auxiliary device.

[0103] In the stage of obtaining system operation data, the 24-hour operation data of the system under the traditional AGC control mode as Scheme 1, the simple energy storage auxiliary control mode as Scheme 2 and the dual-objective optimization control mode of the present invention as Scheme 3 were recorded respectively. Among them, Scheme 2 adopts a fixed 7:3 power allocation ratio, and Scheme 3 adopts the optimization method proposed by the present invention to dynamically allocate power. The system operation parameters are set as follows: the energy storage power limit is ±40MW, the SOC operation range is 20%-90%, and the unit climbing rate is limited to 2% rated power / minute. The parameters in the loss cost model are optimized and set: dc=0.015, fc=0.008, dg=0.025. The weight factors in the dual-objective optimization model are calculated by the entropy weight method: α=0.65, β=0.35.

[0104] A 24-hour comparative test was conducted on the three schemes. During the test, the unit load fluctuated between 180MW and 240MW, and the AGC command was issued every 2 minutes. All operating indicators were fully recorded, and the test data is shown in the following table:

[0105]

[0106] The following conclusions can be drawn from the analysis of the test data:

[0107] In terms of frequency control performance, the dual-objective optimization control scheme (Scheme 3) proposed in the present invention is significantly better than the other two schemes. The root mean square of the frequency deviation is reduced to 18.6mHz, which is 59.4% lower than the traditional AGC control and 42.6% lower than the simple energy storage auxiliary scheme. This shows that the optimization control strategy proposed in the present invention can effectively improve the frequency modulation quality of the system. The frequency modulation response time is greatly shortened from the traditional 185 seconds to 45 seconds, which improves the system's ability to respond quickly to frequency fluctuations.

[0108] In terms of system economy, the daily adjustment times of Scheme 3 are only 245 times, which is significantly lower than the other two schemes. This means that the adjustment intensity of the unit is greatly reduced, effectively reducing the increase in coal consumption and equipment wear. The economic loss cost is reduced from 126,000 yuan / day of the traditional scheme to 72,000 yuan / day, saving 42.9%. This fully demonstrates the advantages of the invention in terms of economy.

[0109] In terms of energy storage system utilization efficiency, Scheme 3 controls the SOC deviation of the energy storage system within 3.2% through optimization control, which is much better than the 8.5% of the simple energy storage auxiliary scheme. This shows that the present invention can better balance the charging and discharging process of the energy storage system and extend the service life of the energy storage system. The smaller SOC deviation also ensures that the energy storage system has sufficient adjustment margin to cope with large power fluctuations.

[0110] In summary, the control scheme based on dual-objective optimization proposed in the present invention has achieved significant improvements in frequency regulation performance, economy and energy storage utilization efficiency. This scheme achieves optimal coordination of frequency control and energy storage balance by establishing an accurate loss cost model and adopting a multi-objective optimization method based on the entropy weight method. The experimental results show that this scheme not only improves the frequency regulation quality of the system, but also significantly reduces the operating cost, and has obvious engineering application value.

[0111] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A coordinated control method for an energy storage system based on dual-objective optimization, characterized in that: include, Connecting the energy storage device to the unit control system and obtaining first operating data; Based on the first operating data, construct an energy storage-unit loss cost model and calculate a first operating reference value; According to the first operating reference value, a dual-objective optimization model of frequency fluctuation and energy storage balance is established; Calculate the energy storage-unit output distribution ratio based on the optimization model; The energy storage system and the unit are jointly frequency-regulated according to the output distribution ratio.

2. The energy storage system coordinated control method based on dual-objective optimization according to claim 1, characterized in that: The step of connecting the energy storage device to the unit control system and obtaining the first operation data includes: connecting the energy storage device to the unit circuit breaker and the plant high-voltage bus according to a preset connection method, and establishing a communication link with the unit control system through the main control unit; When the control device sends a frequency modulation instruction to the unit, the unit responds in the original way. At the same time, the main control unit of the energy storage system collects the frequency modulation instruction, the output of the generator set and the output data of the energy storage device to form the first operating data, which is sampled at a preset frequency.

3. The energy storage system coordinated control method based on dual-objective optimization according to claim 2, characterized in that: The construction of the energy storage-unit loss cost model and calculation of the first operating reference value includes: based on the power fluctuation prediction data within a preset period, and taking the charging and discharging loss of the energy storage system, the battery state of charge loss and the unit power regulation loss as optimization targets, setting conditions including energy storage power limit, state of charge range and unit climbing constraint, and obtaining the system optimal economic operation value as the first operating reference value by minimizing the loss cost.

4. The energy storage system coordinated control method based on dual-objective optimization according to claim 3 is characterized in that: The establishment of the frequency fluctuation and energy storage balance dual-objective optimization model includes: taking the first operating reference value as the optimization benchmark point, constructing a frequency deviation minimization target based on the system real-time fluctuation data, constructing an energy storage quantity balance target according to the charge state of the energy storage system, and using a multi-objective optimization method based on the entropy weight method to coordinately optimize the frequency control performance and the energy storage balance performance.

5. The energy storage system coordinated control method based on dual-objective optimization according to claim 4, characterized in that: The calculation based on the optimization model to obtain the energy storage-unit output distribution ratio includes: updating the energy storage system charge state in real time, calculating the current optimization objective function, and obtaining the optimal power distribution coefficient; Determine whether the preset cycle constraints are met. If so, use the current allocation coefficient as the optimal output allocation ratio and update the operating reference value. If not, continue to optimize and calculate the allocation coefficient at the next moment.

6. The energy storage system coordinated control method based on dual-objective optimization according to claim 5, characterized in that: The loss cost minimization is achieved through the following objective function: Among them, S represents the total value of the combined frequency regulation loss of energy storage and units, and the smaller S is, the smaller the economic loss of the combined frequency regulation of energy storage and units in the preset time period is. T1 represents the power fluctuation time, E(b) represents the frequency regulation loss of the energy storage system at time b, which is determined by the charging and discharging power and the battery state of charge SOC, J(b) represents the frequency regulation loss of the unit at time b, d c Expressed as the energy storage power offset cost coefficient of the energy storage system, P c (b) is expressed as the charging and discharging power of the energy storage system, f c Expressed as the SOC shift cost coefficient, It is expressed as the average value of the SOC of the energy storage system during the preset cycle time. It represents the SOC that the energy storage system can maintain after the preset cycle ends, d g Expressed as the frequency regulation cost coefficient of unit power deviation, P g (b) is the power of the unit participating in the frequency regulation change at time b; The objective function is solved, and the mean value is calculated once every preset time period to finally obtain a first operating reference value.

7. The energy storage system coordinated control method based on dual-objective optimization according to claim 6, characterized in that: The specific implementation of the dual-objective optimization model includes: The frequency modulation performance function Y1 is constructed based on the system deviation coefficient and frequency deviation, the energy storage balance function Y2 is constructed based on the battery state of charge, and the optimization objective function is established: Y=min(αY1+βY2) Wherein, α represents the weight factor of the frequency regulation performance function, β represents the weight factor of the energy storage balance function, and α+β=1; Update the battery state of charge SOC at the kth minute in real time; When the optimization objective function takes the minimum value, the power allocation coefficient between the current energy storage system and the unit is obtained as the optimal compensation coefficient; Determine whether the kth minute is greater than the preset period. If so, use the current optimal compensation coefficient as the output allocation ratio and calculate the reference value for the next period. Otherwise, calculate the optimal compensation coefficient for the k+1th minute.

8. A coordinated control system for an energy storage system based on dual-objective optimization, based on the coordinated control method for an energy storage system based on dual-objective optimization according to any one of claims 1 to 7, characterized in that: It also includes an energy storage status assessment module, a joint optimization control module, and a frequency regulation execution module; The energy storage status assessment module is used to collect unit output data, energy storage power data, and power grid frequency regulation instruction data to establish an energy storage-unit joint operation status assessment model; The joint optimization control module is used to construct a dual-objective optimization model of economic loss and frequency stability based on the system operation status to generate an optimal output distribution ratio; The frequency regulation execution module is used to monitor the energy storage-generator joint frequency regulation process, coordinate the energy storage system and the generator through the allocation ratio, and regularly update and optimize the frequency regulation control strategy.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the energy storage system coordinated control method based on dual-objective optimization described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the energy storage system coordinated control method based on dual-objective optimization described in any one of claims 1 to 7 are implemented.

Images