Method and system for adjusting output coefficient of auxiliary thermal power generating unit of electrochemical energy storage system

Abstract

The invention discloses a method and system for adjusting the output coefficient of an auxiliary thermal power generating unit of an electrochemical energy storage system, and relates to the field of power grid frequency modulation control, and the method comprises the steps: determining an energy storage output distribution coefficient k1 and a thermal power generating unit output coefficient k2 at a frequency modulation starting stage, and adjusting k1 and k2 to meet the demands after the frequency deviation reaches the maximum value; when the power grid frequency deviation exceeds an energy storage frequency modulation dead zone, analyzing frequency change characteristics to obtain specific gravity coefficients omega1 and omega2 for adaptively adjusting energy storage output; omega 1 and Omega 2 are set according to different frequency modulation stages so as to distribute the output proportion of virtual inertia control and virtual droop control. The invention provides a control strategy for adaptively adjusting the electrochemical energy storage frequency modulation output based on the frequency deviation. An active-disturbance-rejection controller is used for deep output control of a traditional thermal power generating unit, the stability of a system is judged through a frequency domain analysis method, and optimal controller parameters are obtained.

Description

Technical Field

[0001] The present invention relates to the field of power grid frequency regulation control, and in particular to a method and system for regulating the output coefficient of an electrochemical energy storage system assisting a thermal power unit. Background Art

[0002] Due to the randomness and volatility of new energy, the smooth operation of the power grid faces huge challenges. However, using high-penetration new energy to compensate for traditional power generation systems will reduce the system's inertia and frequency regulation capacity. Thermal power has the characteristics of slow response, low precision and large capacity, and cannot achieve fast frequency regulation. Energy storage systems with fast response and high control accuracy cannot meet the frequency regulation capacity requirements. Therefore, it will be difficult to maintain the stability of the power grid with only a single frequency regulation system.

[0003] Compared with other energy storage methods, electrochemical energy storage systems, such as lithium-ion batteries and supercapacitors, have the ability to charge and discharge quickly, and can respond to changes in grid frequency within milliseconds, thereby quickly adjusting the active power output of the power system. And because the regulation deviation of electrochemical energy storage systems is generally small, much smaller than that of thermal power units, it can achieve high-precision regulation of grid frequency.

[0004] The electrochemical energy storage and thermal power coordinated frequency regulation technology requires coordinated control between the energy storage system and the thermal power units. This requires that the two maintain a high degree of consistency in terms of response speed, regulation accuracy and stability, and the access of the energy storage system may change the dynamic characteristics of the original power system, thereby affecting the stability of the system. In particular, when a power system fails or is abnormal, the response and control strategy of the energy storage system needs to be robust.

[0005] The core of electrochemical energy storage and thermal power coordinated frequency regulation technology is to ensure effective coordination and control between the energy storage system and the thermal power unit. To this end, the two must achieve a high degree of coordination in multiple key performance indicators such as response speed, regulation accuracy and stability to achieve seamless cooperation and efficient operation.

[0006] In order to effectively coordinate the control of electrochemical energy storage and thermal power units, this patent proposes a frequency modulation control method for electrochemical energy storage-thermal power complementation. It aims to eliminate the potential impact of the access of the electrochemical energy storage system on the stability of the system. In particular, when the power system encounters a fault or abnormal situation, it ensures that the system can maintain stable operation with sufficient robustness. Summary of the invention

[0007] In view of the above-mentioned problems, the present invention is proposed.

[0008] Therefore, the problem to be solved by the present invention is: how to achieve effective coordinated control between electrochemical energy storage and thermal power generation units.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for adjusting the output coefficient of an electrochemical energy storage system to assist a thermal power unit, which comprises: determining the energy storage output allocation coefficient k1 and the thermal power unit output coefficient k2 at the beginning of the frequency modulation stage; when the frequency deviation reaches the maximum value, adjusting k1 and k2 to meet the demand; when the grid frequency deviation exceeds the energy storage frequency modulation dead zone, obtaining the weight coefficients ω1 and ω2 for adaptively adjusting the energy storage output by analyzing the frequency change characteristics; setting ω1 and ω2 according to different frequency modulation stages to allocate the output ratios of virtual inertia control and virtual droop control.

[0010] As a preferred solution of the method for adjusting the output coefficient of the electrochemical energy storage system assisting the thermal power unit of the present invention, when the frequency regulation is in the starting stage, the energy storage output distribution coefficient k1 and the thermal power unit output coefficient k2 are determined to be expressed as:

[0011]

[0012] Among them, Δf represents the current frequency deviation, f db Expressed as the energy storage action dead zone limit, Δf g Expressed as the maximum frequency deviation allowed by the power grid.

[0013] As a preferred solution of the method for adjusting the output coefficient of the electrochemical energy storage system auxiliary thermal power unit of the present invention, when the frequency deviation reaches the maximum value, k1 and k2 are adjusted to meet the demand, and the adjusted k1 and k2 are expressed as:

[0014]

[0015] Among them, n represents the adjustment coefficient, f set Expressed as the steady-state frequency deviation of the power grid.

[0016] As a preferred solution of the method for adjusting the output coefficient of the electrochemical energy storage system assisting the thermal power unit described in the present invention, the frequency regulation stage includes a deterioration stage, a maximum frequency deviation point stage and a frequency recovery stage.

[0017] As a preferred solution of the method for adjusting the output coefficient of the electrochemical energy storage system auxiliary thermal power unit of the present invention, wherein: the setting of ω1 and ω2 according to different frequency modulation stages includes that when the frequency modulation stage is the deterioration stage, the frequency control mode is mainly inertial control, supplemented by droop control, and ω1 and ω2 are expressed as,

[0018]

[0019] Among them, n1 represents the adjustment coefficient.

[0020] As a preferred solution of the method for adjusting the output coefficient of the electrochemical energy storage system auxiliary thermal power unit of the present invention, wherein: the setting of ω1 and ω2 according to different frequency modulation stages also includes, when the frequency modulation stage is the maximum frequency deviation point stage, using virtual droop control to suppress the maximum frequency deviation, ω1 and ω2 are expressed as,

[0021]

[0022] Among them, n2 represents the adjustment coefficient.

[0023] As a preferred solution of the method for adjusting the output coefficient of the electrochemical energy storage system auxiliary thermal power unit of the present invention, wherein: the setting of ω1 and ω2 according to different frequency modulation stages also includes that when the frequency modulation stage is the recovery stage, ω1 and ω2 are expressed as,

[0024]

[0025] Another object of the present invention is to provide a system for adjusting the output coefficient of an electrochemical energy storage system to assist a thermal power unit, which can perform frequency modulation control on a power grid.

[0026] To solve the above technical problems, the present invention provides the following technical solutions: a system for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit, comprising: an output distribution coefficient adjustment module, a weight coefficient determination module and an output ratio distribution module; at the beginning of frequency modulation, the output distribution coefficient adjustment module determines the energy storage output distribution coefficient k1 and the thermal power unit output coefficient k2, and when the frequency deviation reaches a maximum value, adjusts k1 and k2 to meet the demand; when the grid frequency deviation exceeds the energy storage frequency modulation dead zone, the weight coefficient determination module obtains the weight coefficients ω1 and ω2 for adaptively adjusting the energy storage output by analyzing the frequency change characteristics; the output ratio distribution module sets ω1 and ω2 according to different frequency modulation stages to distribute the output ratios of virtual inertia control and virtual droop control.

[0027] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit as described above are implemented.

[0028] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit as described above.

[0029] The beneficial effects of the present invention are as follows: the present invention utilizes the rapid charging and discharging capability of the electrochemical energy storage system to respond to the needs of the power grid or equipment within milliseconds, and proposes a control strategy for adaptively adjusting the frequency modulation output of the electrochemical energy storage system based on the frequency deviation. An anti-disturbance controller is used on the deep output control of the traditional thermal power unit, and the frequency domain analysis method is used to determine the stability of the system and obtain the optimal controller parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing 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. Among them:

[0031] Figure 1 This is a flow chart of the method for adjusting the output coefficient of the electrochemical energy storage system assisting the thermal power unit in Example 1.

[0032] Figure 2 This is a frequency regulation process diagram of the method for regulating the output coefficient of the electrochemical energy storage system assisting the thermal power unit in Example 1.

[0033] Figure 3 This is a module structure diagram of the system for adjusting the output coefficient of the electrochemical energy storage system assisting the thermal power unit in Example 2. DETAILED DESCRIPTION

[0034] 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.

[0035] 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.

[0036] Example 1, reference Figure 1 and Figure 2 , which is the first embodiment of the present invention, and which provides a method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit, including: Figure 1 As shown:

[0037] S1. At the beginning of frequency regulation, determine the energy storage output allocation coefficient k1 and the thermal power unit output coefficient k2. When the frequency deviation reaches the maximum value, adjust k1 and k2 to meet the demand.

[0038] Electrochemical energy storage systems have the characteristics of fast response speed and high control accuracy. Therefore, in the stage of rapid frequency change, the energy storage system can be used to adjust the grid frequency in time. For the stage of relatively stable frequency, the sufficiently large frequency regulation capacity of thermal power units can maintain the stability of grid frequency for a long time. Therefore, the appropriate distribution of output ratio can better adjust the grid frequency.

[0039] At the beginning of frequency regulation, the frequency changes rapidly, and the energy storage output needs to be increased to quickly respond to the frequency deviation change. At this time, a larger energy storage output allocation coefficient k1 is required. In order to reduce the maximum frequency deviation during the regulation process, it is necessary to increase the output ratio of the thermal power unit to achieve this. Therefore, the thermal power unit output coefficient k2 should be gradually increased during the frequency regulation process. The energy storage output allocation coefficient k1 and the thermal power unit output coefficient k2 are expressed as,

[0040]

[0041] Among them, Δf represents the current frequency deviation, f db Expressed as the energy storage action dead zone limit, Δf g Expressed as the maximum frequency deviation allowed by the power grid.

[0042] When the frequency deviation reaches the maximum value, the grid frequency needs to be restored to a stable value. At this time, the frequency deviation is quickly restored by increasing the energy storage output ratio until it stabilizes. At the same time, for the frequency change stage, the allocation coefficient should be adjusted to allow energy storage to participate in frequency regulation in a timely manner. For the frequency recovery stage, SOC recovery should be guaranteed. The adjusted k1 and k2 are expressed as,

[0043]

[0044] Among them, n represents the adjustment coefficient, f set Expressed as the steady-state frequency deviation of the power grid.

[0045] S2. When the grid frequency deviation exceeds the dead zone of energy storage frequency regulation, the weight coefficients ω1 and ω2 for adaptively adjusting the energy storage output are obtained by analyzing the frequency change characteristics, and then the output ratios of virtual inertia and virtual droop control are dynamically allocated according to them, so as to obtain the appropriate output depth of energy storage in different stages.

[0046] Virtual inertia control is more suitable for conditions where the grid frequency changes rapidly. When the frequency deviation is large, droop control has a better effect on frequency regulation. Therefore, when the frequency changes sharply, the virtual inertia control ratio is increased; when the frequency deviation is large, the droop control ratio is increased. The weight coefficient is defined as a function that changes with frequency: ω1+ω2=1 is always maintained throughout the regulation process.

[0047] Take negative disturbance as an example. When the system disturbance suddenly increases (Δf≤0), the frequency modulation process is as follows: Figure 2The frequency change process is divided into the frequency deterioration stage (-Δf max ≤Δf<-Δf db ), the maximum frequency deviation point (Δf = -Δf max ) and frequency recovery phase (t>t max ). Figure 2 Middle: |Δf max | and |Δf s | are the maximum frequency deviation and steady-state frequency deviation respectively; t max ,t s They are the maximum frequency deviation moment and the frequency deviation stable moment respectively.

[0048] S3. Set ω1 and ω2 according to different frequency modulation stages to allocate the output ratio of virtual inertia control and virtual droop control.

[0049] Frequency deterioration stage: When the power grid is disturbed, the frequency deviation change rate |dΔf| suddenly increases. As the frequency deviation |Δf| gradually increases, the frequency deviation change rate |dΔf| decreases accordingly; when |Δf| reaches its maximum value, |dΔf| decreases to 0. Therefore, ω1 first appears at a larger value and then decreases, and ω2 first appears at a smaller value and then increases. At this time, the frequency control method is mainly inertial control, supplemented by droop control. ω1 and ω2 are expressed as,

[0050]

[0051] Among them, n1 represents the adjustment coefficient.

[0052] Frequency deviation maximum point stage: |Δf| reaches the maximum value and dΔf is 0. Therefore, ω1 takes the value of 0. At this time, it is only necessary to use virtual droop control to suppress the maximum frequency deviation and let |Δfmax| decrease rapidly. ω1 and ω2 are expressed as,

[0053]

[0054] Among them, n2 represents the adjustment coefficient.

[0055] Frequency recovery stage. |Δf| gradually decreases, and |dΔf| first increases and then decreases. This stage is mainly to suppress Δf. Therefore, ω1 appears at a smaller value and then gradually increases, and ω2 appears at a larger value and then gradually decreases. In this way, the role of virtual droop control and inertia control can be fully utilized to accelerate frequency recovery. ω1 and ω2 are expressed as,

[0056]

[0057] Example 2, reference Figure 3, which is the second embodiment of the present invention, and is different from the first embodiment in that: a system for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit, comprising an output distribution coefficient adjustment module 100, a weight coefficient determination module 200 and an output ratio distribution module 300; at the beginning of frequency regulation, the output distribution coefficient adjustment module 100 determines the energy storage output distribution coefficient k1 and the thermal power unit output coefficient k2, and when the frequency deviation reaches the maximum value, adjusts k1 and k2 to meet the demand; when the grid frequency deviation exceeds the energy storage frequency regulation dead zone, the weight coefficient determination module 200 obtains the weight coefficients ω1 and ω2 for adaptively adjusting the energy storage output by analyzing the frequency change characteristics; the output ratio distribution module 300 sets ω1 and ω2 according to different frequency regulation stages to distribute the output ratios of virtual inertia control and virtual droop control.

[0058] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0059] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0060] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0061] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0062] 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 method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit, characterized in that: include, At the beginning of frequency regulation, the energy storage output allocation coefficient k1 and the thermal power unit output coefficient k2 are determined. When the frequency deviation reaches the maximum value, k1 and k2 are adjusted to meet the demand. When the grid frequency deviation exceeds the dead zone of energy storage frequency regulation, the weight coefficients ω1 and ω2 of energy storage output are adaptively adjusted by analyzing the frequency variation characteristics; ω1 and ω2 are set according to different frequency modulation stages to allocate the output ratio of virtual inertia control and virtual droop control.

2. The method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit according to claim 1, characterized in that: At the beginning of the frequency regulation, the energy storage output allocation coefficient k1 and the thermal power unit output coefficient k2 are determined as follows: in, Δf Represents the current frequency deviation, f db It is indicated as the dead zone limit of energy storage action. Δf g Expressed as the maximum frequency deviation allowed by the power grid.

3. The method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit according to claim 2, characterized in that: When the frequency deviation reaches the maximum value, k1 and k2 are adjusted to meet the demand. The adjusted k1 and k2 are expressed as: in, n Expressed as the adjustment coefficient, f set Expressed as the steady-state frequency deviation of the power grid.

4. The method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit according to claim 3, characterized in that: The frequency modulation stage includes a deterioration stage, a maximum frequency deviation point stage and a frequency recovery stage.

5. The method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit according to claim 4, characterized in that: The setting of ω1 and ω2 according to different frequency modulation stages includes that when the frequency modulation stage is a deterioration stage, the frequency control mode is mainly inertial control, supplemented by droop control, and ω1 and ω2 are expressed as, in, n1 Expressed as adjustment coefficient.

6. The method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit according to claim 5, characterized in that: The setting of ω1 and ω2 according to different frequency modulation stages also includes, when the frequency modulation stage is the maximum frequency deviation point stage, using virtual droop control to suppress the maximum frequency deviation, ω1 and ω2 are expressed as, in, n2 Expressed as adjustment coefficient.

7. The method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit according to claim 6, characterized in that: The setting of ω1 and ω2 according to different frequency modulation stages also includes that when the frequency modulation stage is a recovery stage, ω1 and ω2 are expressed as, 8. A system using the method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit as claimed in any one of claims 1 to 7, characterized in that: It comprises an output distribution coefficient adjustment module (100), a specific gravity coefficient determination module (200) and an output ratio distribution module (300); At the beginning of frequency regulation, the output distribution coefficient adjustment module (100) determines the energy storage output distribution coefficient k1 and the thermal power unit output coefficient k2, and when the frequency deviation reaches a maximum value, adjusts k1 and k2 to meet the demand; When the grid frequency deviation exceeds the energy storage frequency regulation dead zone, the weight coefficient determination module (200) obtains weight coefficients ω1 and ω2 for adaptively adjusting the energy storage output by analyzing the frequency variation characteristics; The output ratio distribution module (300) sets ω1 and ω2 according to different frequency modulation stages to distribute the output ratios of virtual inertia control and virtual droop control.

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 method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit according to 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 method for adjusting the output coefficient of an electrochemical energy storage system assisting a thermal power unit according to any one of claims 1 to 7 are implemented.

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