Hybrid energy storage precise frequency division control method and system suitable for emergency power supply scenarios

Abstract

The present invention proposes a hybrid energy storage precise frequency division control method and system suitable for emergency power supply scenarios, and relates to the field of hybrid energy storage control technology. It includes building a hybrid energy storage system structure that forms a ring topology; considering the frequency division error caused by the cable resistance from the output end of the energy storage converter to the bus node, and the cable resistance between the bus nodes, adding a voltage correction term to each energy storage converter to compensate for the voltage drop caused by the cable resistance from the output end of the energy storage converter to the bus node, and the cable resistance between the bus nodes; based on the set energy storage converter expected voltage and the additional voltage correction term, a new expected voltage is obtained; the actual output voltage of the energy storage converter is obtained, so that the actual output voltage tracks the new expected voltage, and the switch control of the bidirectional converter on each energy storage converter is realized according to the tracking result, thereby realizing precise frequency division of the hybrid energy storage system. The present invention realizes precise power frequency division control of the hybrid energy storage system.

Description

Technical Field

[0001] The present invention belongs to the technical field of hybrid energy storage control, and in particular relates to a hybrid energy storage precise frequency division control method and system suitable for emergency power supply scenarios. Background Art

[0002] Traditional diesel power generation systems used as emergency power sources have problems such as poor ability to cope with impact loads, waveform distortion, high daily maintenance costs, and unreliable startup, making it difficult to cope with loads such as DC speed regulation systems. Supercapacitors have the characteristics of high power density and fast dynamic response speed, but their energy density is low; while energy storage batteries have the characteristics of low power density and slow dynamic response speed, but their energy density is high. Hybrid energy storage formed by a combination of two energy storages with complementary characteristics will have the characteristics of high energy density and high power density, and can extend the service life of energy storage and improve the operating efficiency of the system. The above-mentioned hybrid energy storage device based on advanced control technology can solve difficult problems that diesel generators are difficult to deal with, and is therefore more suitable for use as an emergency power supply system.

[0003] Ring topology is often deployed in many practical applications, such as military camps, offshore wind farms, and shipboard power supplies, because it is more reliable than radial topology. However, in recent years, there have been relatively few studies on power frequency division control of hybrid energy storage systems with ring topology.

[0004] When natural disasters occur, energy supply is often severely disrupted, causing power outages. Energy storage power stations are needed as emergency power supply systems that can quickly start and provide stable power supply to disaster-stricken areas. The hybrid energy storage system based on the ring topology can quickly provide high power demand in a short period of time, making up for the defects of a single energy storage device in energy density or capacity, thereby balancing the energy demand of the power grid or equipment; the hybrid energy storage system has a variety of equipment types, and the fluctuation range of its energy output is smaller than that of a single energy storage device, so it is not easy to have problems such as unstable energy supply, and enhance the stability of energy supply; different energy storage devices have different usage rules and life cycles. Through the hybrid energy storage system, each device can work together to reduce the pressure and wear of the energy storage equipment, thereby extending the service life of the equipment; and the ring topology has one more flow channel than the chain radial topology, so the ring topology has better redundancy and higher reliability, effectively improving the system's fault tolerance and power supply continuity.

[0005] However, the existing HESS circuit topology is mostly radial topology, that is, distributed power sources such as photovoltaic power generation and wind power, energy storage units such as batteries and supercapacitors, and various AC loads and DC loads are connected to a common DC bus through their own power electronic converters. This structure is relatively easy to protect and control, but when a fault occurs at the DC bus, it will affect the power supply reliability and stable operation of the entire system.

[0006] The existing power frequency division control strategies can be divided into two types: centralized control and distributed control. Centralized control is mainly based on filter decomposition, including smoothing filter algorithms such as low-pass filter, wavelet decomposition, wavelet packet decomposition, and piecewise function allocation. This method is simple to control, but it requires the central processing unit to perform power difference to obtain the high-frequency or low-frequency components of power, so centralized control is highly dependent on communication. Therefore, there are a series of problems such as single point failure, large amount of calculation, and communication failure.

[0007] In view of the problems existing in the above centralized control, a distributed control that introduces virtual capacitors to form traditional virtual impedance control based on virtual resistance droop control is proposed, which realizes the frequency division response of hybrid energy storage to power. However, the existing HESS power control based on virtual impedance control does not consider the power frequency division error caused by the existence of cable resistance, which leads to the problems of reduced HESS energy storage life, reduced efficiency, and reduced stability of microgrid operation. Summary of the invention

[0008] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a hybrid energy storage precise frequency division control method and system suitable for emergency power supply scenarios, adopts a hybrid energy storage system with a ring topology structure, effectively improves the system's fault tolerance and power supply continuity, and takes into account the influence of the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between nodes on the HESS power distribution accuracy, and combines the actual working conditions to achieve precise power division control of the hybrid energy storage system.

[0009] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0010] A first aspect of the present invention provides a hybrid energy storage precise frequency division control method suitable for emergency power supply scenarios.

[0011] A hybrid energy storage precise frequency division control method applicable to emergency power supply scenarios includes the following steps:

[0012] The energy storage converter is connected to the busbar node of the ring cable through a bidirectional converter, and the local load is connected in parallel to the output side of the energy storage converter to form a hybrid energy storage system structure with a ring topology;

[0013] Considering the frequency division error caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between the bus nodes, a voltage correction item is added to each energy storage converter to compensate for the voltage drop caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between the bus nodes;

[0014] Based on the set expected voltage of the energy storage converter and the additional voltage correction term, a new expected voltage is obtained;

[0015] The actual output voltage of the energy storage converter is obtained so that the actual output voltage tracks the new expected voltage, and the switching control of the bidirectional converter on each energy storage converter is realized according to the tracking result, thereby realizing the precise frequency division of the hybrid energy storage system.

[0016] A second aspect of the present invention provides a hybrid energy storage precise frequency division control system suitable for emergency power supply scenarios.

[0017] Hybrid energy storage precise frequency control system suitable for emergency power supply scenarios, including:

[0018] The ring topology building module is configured to: connect the energy storage converter to the bus node of the ring cable through the bidirectional converter respectively, and connect the local load in parallel to the output side of the energy storage converter to form a hybrid energy storage system structure of the ring topology;

[0019] The compensation module is configured to: consider the frequency division error caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between the bus nodes, add a voltage correction item to each energy storage converter, and compensate for the voltage drop value caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between the bus nodes;

[0020] The correction module is configured to: obtain a new expected voltage based on the set expected voltage of the energy storage converter and the additional voltage correction term;

[0021] The tracking control module is configured to: obtain the actual output voltage of the energy storage converter, make the actual output voltage track the new expected voltage, and implement switch control of the bidirectional converter on each energy storage converter according to the tracking result, thereby realizing accurate frequency division of the hybrid energy storage system.

[0022] The third aspect of the present invention provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, implements the steps in the hybrid energy storage precise frequency division control method suitable for emergency power supply scenarios as described in the first aspect of the present invention.

[0023] The fourth aspect of the present invention provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, the steps in the hybrid energy storage precise frequency division control method suitable for emergency power supply scenarios as described in the first aspect of the present invention are implemented.

[0024] One or more of the above technical solutions have the following beneficial effects:

[0025] The present invention discloses a hybrid energy storage precise frequency division control method and system suitable for emergency power supply scenarios, which is mainly used to solve the HESS power division error problem considering the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between nodes. By analyzing the HESS virtual impedance control of a multi-node ring topology, it is found that the main factors causing the above errors are the influence of line resistance and interconnection line resistance. Then, an improved virtual impedance control is proposed and designed, which is applied to HESS control to eliminate the above errors. By using voltage compensation, the voltage compensation value can be updated in real time based on the estimation of cable resistance, so that the HESS can achieve precise power division control under the ring topology.

[0026] The present invention adopts a hybrid energy storage system with a ring topology, that is, the hybrid energy storage is connected to respective bus nodes through a bidirectional converter, and the bus nodes are interconnected by cables. Compared with the traditional radial topology, the system's fault tolerance and power supply continuity can be effectively improved.

[0027] The control method provided by the present invention takes into account the frequency division error caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between nodes, and adds a voltage correction item to each energy storage converter in combination with actual working conditions to compensate for the voltage drop caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between bus nodes, thereby ultimately achieving precise power frequency division control of the hybrid energy storage system.

[0028] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0030] Figure 1 This is the structural diagram of the ring topology hybrid energy storage system.

[0031] Figure 2 This is the equivalent circuit diagram of the three-node ring topology hybrid energy storage system.

[0032] Figure 3 This is the equivalent circuit diagram of a four-node ring topology hybrid energy storage system.

[0033] Figure 4 This is the equivalent circuit diagram of the n-node ring topology hybrid energy storage system.

[0034] Figure 5 Simplified equivalent circuit diagram of n-node ring topology hybrid energy storage system.

[0035] Figure 6 This is the block diagram of precise frequency division control of hybrid energy storage system based on ring topology.

[0036] Figure 7 This is the equivalent circuit of the ring topology hybrid energy storage system after the proposed control optimization. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] It should be noted that the terms used herein are for describing specific embodiments only and are not intended to be limiting of exemplary embodiments according to the present invention.

[0039] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0040] Embodiment 1

[0041] The embodiments of the present invention provide a method for analyzing the HESS power division error under a ring circuit topology structure, taking into account the cable resistance from the output end of an energy storage converter to a bus node and the cable resistance between nodes, and a method for eliminating the above power division error based on improved virtual impedance control.

[0042] The technical problems solved by the embodiments of the present invention are as follows:

[0043] (1) Ring topology is particularly important in emergency power rescue scenarios due to its high reliability and flexibility. Especially under extreme conditions, the stability and reliability of power supply are crucial, and the ring topology can effectively improve the system's fault tolerance and power supply continuity.

[0044] Therefore, it is necessary to accelerate the research on HESS power division control for ring topology to solve the problem of demand for reliable emergency power supply.

[0045] (2) Considering the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between nodes, the cable resistance will reduce the power distribution accuracy of the HESS or even make it unbalanced, thus affecting its reliable and stable operation in emergency power supply scenarios.

[0046] Therefore, it is necessary to study the above-mentioned frequency division error problem in order to achieve reasonable distribution of power within the system, maintain bus voltage stability and safe operation of the system.

[0047] Specifically, Figure 1 and Figure 6As shown, this embodiment discloses a hybrid energy storage precise frequency division control method applicable to emergency power supply scenarios, which may include the following steps:

[0048] The energy storage converter is connected to the busbar node of the ring cable through a bidirectional converter, and the local load is connected in parallel to the output side of the energy storage converter to form a hybrid energy storage system structure with a ring topology;

[0049] Considering the frequency division error caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between the bus nodes, a voltage correction item is added to each energy storage converter to compensate for the voltage drop caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between the bus nodes;

[0050] Based on the set expected voltage of the energy storage converter and the additional voltage correction term, a new expected voltage is obtained;

[0051] The actual output voltage of the energy storage converter is obtained so that the actual output voltage tracks the new expected voltage, and the switching control of the bidirectional converter on each energy storage converter is realized according to the tracking result, thereby realizing the precise frequency division of the hybrid energy storage system.

[0052] Furthermore, the detailed technical solution of this embodiment includes:

[0053] 1. First, the structure of the ring topology hybrid energy storage system and the HESS power division error considering the cable resistance are introduced:

[0054] 1) The structure of the hybrid energy storage system based on ring topology is now introduced.

[0055] like Figure 1 As shown, the structural diagram of the ring topology hybrid energy storage system is given.

[0056] k energy storage battery groups and nk supercapacitor groups are connected to the ring cable through their own bidirectional DC converters, and the local load is connected in parallel to the output side of the energy storage converter to form an n-node ring topology hybrid energy storage system. bat and V sc are the output voltages of the energy storage battery and supercapacitor, i bat1 、i sc1 and i scn-k are the output currents of energy storage battery converter 1, supercapacitor converter 2 and supercapacitor converter nk, respectively. 12 、i 23 、i n-1n and i 1n is the tie line current. The local loads at node 1, node 2 and node n are R load1 , R load2 and R loadnThe energy storage converter has a resistor R line1 , R line2 and R linen The bus node is connected to the bus node through the resistor R 12 , R 23 , R n-1n and R 1n The contact line connection.

[0057] 2) Now, based on the ring topology system with different number of nodes, the HESS power division error under cable resistance is considered:

[0058] Figure 2 This is the equivalent circuit diagram of the three-node ring topology hybrid energy storage system.

[0059] Among them, V ref is the expected DC bus voltage, V β1 、V β2 and V β3 is the compensation voltage of each branch, R b1 and R b2 are the virtual resistances of energy storage battery 1 branch and energy storage battery 2 branch, C c1 is the virtual capacitance value of supercapacitor 1 branch, the load resistance, the line resistance from the output side of the energy storage converter to the bus node, and the tie line resistance between the bus nodes are the same as above and will not be repeated. Assume that the direction of the tie line current is as follows Figure 2 As shown, the Kirchhoff voltage equation for this system is written as

[0060]

[0061] Let’s not consider the compensation voltage V used in the subsequent control. β , set V β1 、V β2 、V β3 =0, and by combining formula (1) and formula (2) to eliminate the tie line current, the output current relationship of each converter can be obtained as follows:

[0062]

[0063] According to the analysis of formula (3), in the three-node ring network topology, due to the line resistance R connecting the energy storage converter and the bus node line1 , R line2 and R line3 , the tie line resistance R between busbar nodes 12 , R 23 , R 13 The existence of leads to the power division error of HESS.

[0064] Figure 3This is the equivalent circuit diagram of a four-node ring topology hybrid energy storage system. The symbols represent the same meaning as Figure 2 Similar to the three-node case, assume that the direction of the tie line current is Figure 3 As shown, the Kirchhoff voltage equation for this system is written as

[0065]

[0066] Similarly, the power division error of HESS is caused by the existence of line resistance from converter to bus node and tie line resistance between bus nodes.

[0067] It is not difficult to find that there are certain rules in the ring topology system through three nodes and four nodes. Figure 4 is the equivalent circuit diagram of the n-node ring topology hybrid energy storage system. Figure 4 Simplified to Figure 5 , the energy storage system branch is no longer subdivided into supercapacitor branch and energy storage battery branch. Among them, V ref is the expected DC bus voltage, V β1 、V β2 ···V βn is the compensation voltage of each branch, Z1, Z2...Z n is the virtual impedance of each branch (where the virtual impedance corresponding to the energy storage battery is the virtual resistance R b , the virtual impedance corresponding to the supercapacitor is the virtual capacitor C c ),i dc1 、i dc2 ···i dcn The output current of each branch, the line resistance from the output side of the energy storage converter to the bus node, and the tie line resistance between the bus nodes are consistent with the above. The Kirchhoff voltage equation can be written as

[0068] V ref -i dci (Z i +R linei )-(i dci -i ij -i ik )R loadi =0 (6)

[0069] V ref -i dci (Z i +R linei )-i ij R ij +i dcj (Z j +R linej )-V ref =0 (7)

[0070] The combinations of i, j, and k are shown in Table 1.

[0071] Table 1 n-node ring system i, j, k combination

[0072]

[0073] 2. The following introduces the principle of improving virtual impedance control to achieve HESS precise frequency division control:

[0074] The proposed improved virtual impedance control method can be used to eliminate the influence of line resistance and tie line resistance that cause frequency division error. Its principle is briefly described as follows:

[0075] like Figure 5 As shown, a voltage correction term V is added to each energy storage converter. β After adopting the proposed control, equations (6) and (7) can be written as new equations:

[0076] V ref +V βi -i dci (Z i +R linei )-(i dci -i ij -i ik )R loadi =0 (8)

[0077] V ref +V βi -i dci (Z i +R linei )-i ij R ij +i dcj (Z j +R linej )-V βj -V ref =0 (9)

[0078] At the same time, the desired output of the ith node and the jth node converter is inversely proportional to the corresponding virtual impedance value, that is,

[0079] i dci Z i =i dcj Z j (10)

[0080] From equations (8), (9) and (10), we can deduce V that can achieve accurate output between the i-th node and the j-th node converter: βi and V βj The relationship is:

[0081] V βi -V βj =i dci R linei +i ij R ij -i dcj R linej (11)

[0082] In the proposed control, V βi It is divided into V′ βi and V" βi And given by:

[0083] V βi =V β ' i +V β ″ i (12)

[0084] V′ βi and V" βi They are used to eliminate the line resistance R linei And the tie line resistance R ij The effect of voltage drop on the βi Given by formula (13), V" βi and V" βj The relationship is given by formula (14):

[0085] V β ' i =i dci R linei (13)

[0086] V″ βi -V″ βj =i ij R ij (14)

[0087] V′ βi The meaning is: the first voltage correction term added to the i-th energy storage converter, eliminating the line resistance R from the converter output port to the i-th bus node linei The impact of voltage drop on the

[0088] V″ βj The meaning is: the second voltage correction term added to the j-th energy storage converter, which is the same as the second voltage correction term V" added to the ith energy storage converter βi Working together, the resistance R of the connecting line from node i to node j is eliminated. ij The impact of voltage drop on the

[0089] The combinations of i, j, and k are shown in Table 2.

[0090] Table 2 n-node ring system i, j, k combination

[0091]

[0092] When voltage compensation is performed according to equations (13) and (14), the entire hybrid ring energy storage system can be simplified as follows: Figure 7 As shown in the figure, all energy storage battery branches and supercapacitor branches are regarded as a whole, and the output current of HESS can be obtained as:

[0093]

[0094] The current distribution relationship between energy storage branches of different media is:

[0095]

[0096] i sc1 :…:i scn-k =C c1 :…:C cn-k (17)

[0097] In summary, the improved virtual impedance control is used to realize the precise power division control of the n-node HESS in the ring topology.

[0098] 3. The following describes the specific implementation of this embodiment in HESS precise frequency division control:

[0099] The block diagram of precise frequency division control of hybrid energy storage system based on ring topology is as follows: Figure 6 shown. Figure 6 The upper part is the control block diagram of the energy storage battery converter, and the lower part is the control block diagram of the supercapacitor converter. The control methods are roughly the same, except that the underlying virtual impedance Z is different. The virtual impedance of the energy storage battery is R b , the supercapacitor virtual impedance is C c The complex domain transformation of .

[0100] Step 1: The sensor outputs the voltage V dc , output current i bat 、i sc Sampling is performed. And the target output voltage V is set ref , the virtual impedance Z of each branch.

[0101] Step 2: Substitute the output current i obtained in step 1 bat 、i sc A value is obtained by multiplying it by the virtual impedance Z of each branch.

[0102] Step 3: Set the target output voltage V ref Subtract the value from the value obtained in step 2 to get a value.

[0103] Step 4: V′ β According to formula (13), V" β According to formula (14), V′ β With V" β Add together to get the voltage correction term V β .

[0104] Step 5: Substitute the V obtained in step 4 β Add the value obtained in step 3 to get the new expected voltage.

[0105] Step 6: Calculate the new expected voltage obtained in step 5 and the branch output voltage V sampled in step 1 dc The error between .

[0106] Step 7: Send the voltage error obtained in step 6 to the voltage controller.

[0107] Step 8: The PWM modulation module modulates the switch signal according to the output value obtained in step 7 to obtain the modulation signal of the switch device, and sends it to the switch devices corresponding to the bidirectional converter to achieve closed-loop control.

[0108] The voltage controller may adopt a variety of control methods including but not limited to integral control, proportional integral control, predictive control, etc.

[0109] This embodiment analyzes the HESS virtual impedance control of a multi-node ring topology and finds that the main factors causing the above errors are the influence of line resistance and tie line resistance. Then, an improved virtual impedance control is proposed and designed, which is applied to HESS control to eliminate the above errors. This module uses voltage compensation and can update the voltage compensation value in real time based on the estimation of cable resistance, so that HESS can achieve precise power frequency division control under the ring topology.

[0110] Embodiment 2

[0111] This embodiment discloses a hybrid energy storage precise frequency division control system suitable for emergency power supply scenarios.

[0112] Hybrid energy storage precise frequency control system suitable for emergency power supply scenarios, including:

[0113] The ring topology building module is configured to: connect the energy storage converter to the bus node of the ring cable through the bidirectional converter respectively, and connect the local load in parallel to the output side of the energy storage converter to form a hybrid energy storage system structure of the ring topology;

[0114] The compensation module is configured to: consider the frequency division error caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between the bus nodes, add a voltage correction item to each energy storage converter, and compensate for the voltage drop value caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between the bus nodes;

[0115] The correction module is configured to: obtain a new expected voltage based on the set expected voltage of the energy storage converter and the additional voltage correction term;

[0116] The tracking control module is configured to: obtain the actual output voltage of the energy storage converter, make the actual output voltage track the new expected voltage, and implement switch control of the bidirectional converter on each energy storage converter according to the tracking result, thereby realizing accurate frequency division of the hybrid energy storage system.

[0117] Embodiment 3

[0118] The purpose of this embodiment is to provide a computer-readable storage medium.

[0119] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the hybrid energy storage precise frequency division control method applicable to emergency power supply scenarios as described in Example 1 of the present disclosure.

[0120] Embodiment 4

[0121] The purpose of this embodiment is to provide an electronic device.

[0122] An electronic device includes a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, the steps in the hybrid energy storage precise frequency division control method suitable for emergency power supply scenarios as described in Example 1 of the present disclosure are implemented.

[0123] The steps involved in the apparatuses of the above embodiments 2, 3 and 4 correspond to the method embodiment 1, and the specific implementation methods can refer to the relevant description part of embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood to include any medium that can store, encode or carry an instruction set for execution by a processor and enable the processor to execute any method in the present invention.

[0124] Those skilled in the art should understand that the modules or steps of the present invention described above can be implemented by a general-purpose computer device, or alternatively, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. The present invention is not limited to any specific combination of hardware and software.

[0125] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A hybrid energy storage precise frequency division control method suitable for emergency power supply scenarios, characterized in that: The following steps are involved: The energy storage converter is connected to the busbar node of the ring cable through a bidirectional converter, and the local load is connected in parallel to the output side of the energy storage converter to form a hybrid energy storage system structure with a ring topology; Considering the frequency division error caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between the bus nodes, a voltage correction item is added to each energy storage converter to compensate for the voltage drop caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between the bus nodes; Based on the set expected voltage of the energy storage converter and the additional voltage correction term, a new expected voltage is obtained; The actual output voltage of the energy storage converter is obtained so that the actual output voltage tracks the new expected voltage, and the switching control of the bidirectional converter on each energy storage converter is realized according to the tracking result, thereby realizing the precise frequency division of the hybrid energy storage system.

2. The hybrid energy storage precise frequency division control method applicable to emergency power supply scenarios according to claim 1, characterized in that: The additional voltage correction term is calculated as: The energy storage converter is assumed to be k energy storage battery groups and nk supercapacitor groups, and the hybrid energy storage system includes n bus nodes; there is a line resistance R between the i-th energy storage converter and the connected bus node. linej ; Adjacent busbar nodes i and j are connected by tie lines, and the tie line resistance is R ij ; The voltage correction term added to the i-th energy storage converter is V βi , V βi =V β ' i +V β ″ i ,but: V β ′ i =i dci R linei ; V β ″ i -V β ″ j =i ij R ij ; Among them, i dci is the current on the i-th energy storage converter branch; i ij is the current flowing between bus nodes i and j; V β ' i The meaning is: the first voltage correction term added to the i-th energy storage converter, eliminating the line resistance R from the converter output port to the i-th bus node linei The influence of voltage drop on V β ″ j The meaning is: the second voltage correction term added to the j-th energy storage converter, which is the same as the second voltage correction term V" added to the ith energy storage converter βi Working together, the resistance R of the connecting line from node i to node j is eliminated. ij The impact of voltage drop on the 3. The hybrid energy storage precise frequency division control method applicable to emergency power supply scenarios according to claim 1, characterized in that: When calculating the new expected voltage, the influence of the virtual impedance in the energy storage converter also needs to be considered, specifically: Obtain the output current of each branch of the energy storage battery group and the supercapacitor group in the energy storage converter, set the virtual impedance of each branch of the energy storage battery group and the supercapacitor group, and calculate the product of the output current of each branch and the virtual impedance of the corresponding branch; Calculate the difference between the expected voltage of the energy storage converter and the above product; The above difference is added to the additional voltage correction term to finally obtain the new expected voltage.

4. The hybrid energy storage precise frequency division control method applicable to emergency power supply scenarios according to claim 1, characterized in that: The error between the new desired voltage and the actual output voltage of the energy storage converter is calculated, and the error is input into the voltage controller to achieve the tracking of the actual output voltage to the new desired voltage.

5. The hybrid energy storage precise frequency division control method applicable to emergency power supply scenarios as claimed in claim 4 is characterized in that: Using the PWM modulation module to modulate the switch signal according to the output value of the voltage controller, to obtain a modulation signal of the switch device; The above modulation signals are respectively sent to the switching devices of the bidirectional converter of the corresponding energy storage converter to realize closed-loop control.

6. The hybrid energy storage precise frequency division control method applicable to emergency power supply scenarios according to claim 2, characterized in that: When the additional voltage correction term is used for voltage compensation, all energy storage battery branches and supercapacitor branches are considered as a whole, and the output current of the hybrid energy storage system is obtained: Among them, i bat is the total current of all energy storage battery branches; i sc is the total current of all supercapacitor branches; i load is the total current of all loads; R b is the virtual resistance of all energy storage battery branches; C c is the virtual capacitance of all supercapacitor branches.

7. The hybrid energy storage precise frequency division control method applicable to emergency power supply scenarios according to claim 6, characterized in that: The current distribution relationship between energy storage branches of different media is: i sc1 :…:i scn-k =C c1 :…:C cn-k ; Among them, i bat1 …i batk are the current of the first energy storage battery branch…the current of the kth energy storage battery branch respectively; R b1 …R bk are the virtual resistance of the first energy storage battery branch...the virtual resistance of the kth energy storage battery branch respectively; sc1 …i scn-k are the current of the first supercapacitor branch…the current of the (nk)th supercapacitor branch respectively; C c1 …C cn-k They are respectively the virtual capacitance of the first supercapacitor branch…the virtual capacitance of the (nk)th supercapacitor branch.

8. Hybrid energy storage precise frequency control system suitable for emergency power supply scenarios, characterized by: include: The ring topology building module is configured to: connect the energy storage converter to the bus node of the ring cable through the bidirectional converter respectively, and connect the local load in parallel to the output side of the energy storage converter to form a hybrid energy storage system structure of the ring topology; The compensation module is configured to: consider the frequency division error caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between the bus nodes, add a voltage correction item to each energy storage converter, and compensate for the voltage drop value caused by the cable resistance from the output end of the energy storage converter to the bus node and the cable resistance between the bus nodes; The correction module is configured to: obtain a new expected voltage based on the set expected voltage of the energy storage converter and the additional voltage correction term; The tracking control module is configured to: obtain the actual output voltage of the energy storage converter, make the actual output voltage track the new expected voltage, and implement switch control of the bidirectional converter on each energy storage converter according to the tracking result, thereby realizing accurate frequency division of the hybrid energy storage system.

9. A computer-readable storage medium having a program stored thereon, characterized in that: When the program is executed by a processor, the steps in the hybrid energy storage precise frequency division control method suitable for emergency power supply scenarios as described in any one of claims 1 to 7 are implemented.

10. An electronic device comprising a memory, a processor, and a program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps in the hybrid energy storage precise frequency division control method suitable for emergency power supply scenarios as described in any one of claims 1-7 are implemented.

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