Control system, method and energy storage system for an energy storage system

Abstract

The embodiment of the application provides a kind of energy storage system control system, method and energy storage system, the system includes: mode selection module, voltage closed-loop control module, power control module, current closed-loop control module and PWM modulation module, mode selection module is used to determine the working mode of the energy storage capacitor of energy storage system and voltage given value;Voltage closed-loop control module is used to calculate voltage deviation value, and current control value is determined according to voltage deviation value;Power control module is used to determine current given value according to current limit value or current control value, and current limit value is the preset constant power of energy storage capacitor and the ratio of the terminal voltage of energy storage capacitor;Current closed-loop control module is used to calculate current deviation value, and modulation wave is obtained according to current deviation value;PWM modulation module is used to determine converter control pulse according to modulation wave, to control energy storage capacitor, by the above constant power control strategy, the energy saving effect and the voltage stabilizing effect of energy storage system are improved.

Description

Technical Field

[0001] This application relates to the field of capacitor energy storage control technology, and in particular to a control system, method and energy storage system for an energy storage system. Background Technology

[0002] Introducing supercapacitor energy storage systems into urban rail transit power supply systems to store train braking energy for use during train traction not only saves energy but also helps maintain grid voltage stability, and has broad application potential in the urban rail transit field.

[0003] As is well known, the typical power characteristics of train operation are: 1. Traction phase: In the initial stage, the traction power is relatively small, and it gradually increases as the train speed increases; 2. Braking phase: In the initial stage, the braking power is very large, and it gradually decreases as the train speed decreases. Currently, supercapacitor energy storage systems used in rail transit generally adopt a current-limiting control method. That is, during train traction, the supercapacitor provides traction energy to the train in a constant current manner; during train braking, the supercapacitor absorbs the train braking energy in a constant current manner.

[0004] Under the traditional current limiting control method, the power characteristics of supercapacitors are as follows: when supercapacitors release energy (corresponding to the train traction stage), the power is relatively large at the beginning, and the power gradually decreases as the capacitor voltage decreases; when supercapacitors absorb energy (corresponding to the train braking stage), the power is small at the beginning, and the power gradually increases as the capacitor voltage rises.

[0005] Therefore, under traditional current-limiting control, supercapacitors cannot consistently release sufficient power to the traction grid during train traction to suppress voltage drops; nor can they consistently absorb energy from the traction grid to suppress voltage rises during train braking. Consequently, existing control strategies for supercapacitor energy storage systems cannot achieve good voltage stabilization and have low energy utilization. Summary of the Invention

[0006] This application provides a control system, method, and energy storage system for an energy storage system, and provides a constant power control strategy that improves the voltage regulation effect of the energy storage capacitor and the energy utilization rate of the energy storage system.

[0007] In a first aspect, embodiments of this application provide a control system for an energy storage system, the energy storage system including an energy storage capacitor, and the control system including: a mode selection module, a voltage closed-loop control module, a power control module, a current closed-loop control module, and a PWM modulation module;

[0008] The mode selection module is used to determine the operating mode and voltage setpoint of the energy storage capacitor of the energy storage system based on the grid voltage of the traction power supply network.

[0009] The voltage closed-loop control module is used to calculate the voltage deviation between the voltage setpoint and the grid voltage, and to determine the current control value based on the voltage deviation.

[0010] The power control module is used to determine the current setpoint based on the current limit value or the current control value, wherein the current limit value is the ratio of the preset constant charging and discharging power of the energy storage capacitor to the terminal voltage of the energy storage capacitor.

[0011] The current closed-loop control module is used to determine the current deviation value based on the current setpoint and the current value of the energy storage capacitor, and to obtain the modulation wave based on the current deviation value.

[0012] The PWM modulation module is used to determine the converter control pulse based on the modulation wave, so as to control the charging and discharging current of the energy storage capacitor in the operating mode according to the control pulse.

[0013] Optionally, the power control module is specifically used for:

[0014] When the current control value is less than the maximum value of the current limit value, the current setpoint is determined based on the current control value according to the first current setpoint relationship.

[0015] When the current control value is greater than or equal to the maximum value of the current limit value, the current limit value is determined as the current setpoint; wherein, the expression for the current limit value is: I SC_lim (t)=P SC_lim / U SC (t), P SC_lim For the preset constant charging and discharging power, U SC (t) represents the terminal voltage of the energy storage capacitor at time t.

[0016] Optionally, the relationship for the first current setpoint is:

[0017] I ref * (t)=(I ref (t) / I lim_max )×I SC_lim (t)

[0018] I lim_max =P SC_lim / U SC_min

[0019] Among them, U SC_min The minimum permissible terminal voltage of the energy storage capacitor; I ref (t) represents the current control value at time t; I lim_maxThe current limit value I SC_lim The maximum value of (t); I ref * (t) represents the current given value at time t.

[0020] Optionally, the power control module further includes a state-of-charge limiting module, used for:

[0021] When the remaining charge of the energy storage capacitor is higher than the first charge threshold or lower than the second charge threshold, the current setpoint is set to 0.

[0022] Optionally, the relationship for the first current setpoint is:

[0023] I ref * (t)=(I ref (t) / I lim_max )×(P SC_lim / U SC (t))×K SOC

[0024] Wherein, when the working mode is charging mode, K SOC The expression is: When the operating mode is discharge mode, K SOC The expression is: Wherein, SOC is the ratio of the remaining charge of the energy storage capacitor to its maximum charge.

[0025] Optionally, the energy storage capacitor operates intermittently with a working cycle of T0, an actual working time of T, and both a charging and discharging cycle of 0.5T, wherein T0 ≥ T. The control system further includes:

[0026] The preset power determination module is used to determine the preset charge / discharge constant power P of the energy storage capacitor based on preset power limiting conditions before determining the current setpoint according to the current limit value or the current control value. SC The expression for the preset power limit condition is:

[0027]

[0028] Where C is the capacitance of the energy storage capacitor; 0 is the initial time, t∈(0, 0.5T); I SC0 The rated current of the energy storage capacitor is given.

[0029] Optionally, the mode selection module is specifically used for:

[0030] When the grid voltage is greater than the charging voltage threshold of the energy storage capacitor but less than the maximum allowable grid voltage, the operating mode of the energy storage capacitor is determined to be the charging mode, and the voltage setpoint is the charging setpoint.

[0031] When the grid voltage is greater than the minimum allowable grid voltage and less than the discharge voltage threshold of the energy storage capacitor, the operating mode of the energy storage capacitor is determined to be the discharge mode, and the voltage setpoint is the discharge setpoint.

[0032] Optionally, the voltage closed-loop control module includes a voltage deviation calculation module and a voltage PI adjustment module;

[0033] The voltage deviation calculation module is used to calculate the voltage deviation between the voltage setpoint and the grid voltage.

[0034] The voltage PI regulation module is used to determine the current control value based on the voltage deviation value, so as to realize closed-loop control of the grid voltage.

[0035] Secondly, this application also provides a control method for an energy storage system, the method comprising:

[0036] The operating mode and voltage setpoint of the energy storage capacitor of the energy storage system are determined by the mode selection module based on the grid voltage of the traction power supply network.

[0037] The voltage deviation between the voltage setpoint and the grid voltage is calculated via the voltage closed-loop control module, and the current control value is determined based on the voltage deviation.

[0038] The current setpoint is determined by the power control module based on the current limit value or the current control value, wherein the current limit value is the ratio of the preset constant charging and discharging power of the energy storage capacitor to the terminal voltage of the energy storage capacitor.

[0039] The current deviation value is determined based on the current setpoint and the current value of the energy storage capacitor via the current closed-loop control module, and the modulation wave is obtained based on the current deviation value.

[0040] The converter control pulse is determined based on the modulation wave via the PWM modulation module, so as to control the charging and discharging current of the energy storage capacitor in the operating mode according to the control pulse.

[0041] Optionally, determining the operating mode and voltage setpoint of the energy storage capacitor of the energy storage system based on the grid voltage of the traction power supply network includes:

[0042] When the grid voltage is greater than the charging voltage threshold of the energy storage capacitor but less than the maximum allowable grid voltage, the operating mode of the energy storage capacitor is determined to be the charging mode, and the voltage setpoint is the charging setpoint.

[0043] When the grid voltage is greater than the minimum allowable grid voltage and less than the discharge voltage threshold of the energy storage capacitor, the operating mode of the energy storage capacitor is determined to be the discharge mode, and the voltage setpoint is the discharge setpoint.

[0044] Optionally, the voltage closed-loop control module includes a voltage deviation calculation module and a voltage PI regulation module. The calculation of the voltage deviation between the voltage setpoint and the grid voltage includes:

[0045] The voltage deviation calculation module calculates the voltage deviation between the voltage setpoint and the grid voltage.

[0046] Determining the current control value based on the voltage deviation value includes:

[0047] The voltage PI regulation module determines the current control value based on the voltage deviation value to achieve closed-loop control of the grid voltage.

[0048] Optionally, determining the current setpoint based on the current limit value or the current control value includes:

[0049] When the current control value is less than the maximum value of the current limit value, the current setpoint is determined based on the current control value according to the first current setpoint relationship.

[0050] When the current control value is greater than or equal to the maximum value of the current limit value, the current limit value is determined as the current setpoint; wherein, the expression for the current limit value is: I SC_lim (t)=P SC_lim / U SC (t), P SC_lim For the preset constant charging and discharging power, U SC (t) represents the terminal voltage of the energy storage capacitor at time t.

[0051] Optionally, the relationship for the first current setpoint is:

[0052] I ref * (t)=(I ref (t) / I lim_max )×I SC_lim (t)

[0053] I lim_max =P SC_lim / U SC_min

[0054] Among them, U SC_min I is the minimum permissible terminal voltage of the energy storage capacitor; ref(t) represents the current control value at time t; I lim_max The current limit value I SC_lim The maximum value of (t); I ref * (t) represents the current given value at time t.

[0055] Optionally, the power control module further includes a state-of-charge limiting module, and the control method further includes:

[0056] The current setpoint is set to 0 when the remaining charge of the energy storage capacitor is higher than a first charge threshold or lower than a second charge threshold, via the state of charge limiting module.

[0057] Optionally, the relationship for the first current setpoint is:

[0058] I ref * (t)=(I ref (t) / I lim_max )×(P SC_lim / U SC (t))×K SOC

[0059] Wherein, when the working mode is charging mode, K SOC The expression is: When the operating mode is discharge mode, K SOC The expression is: Wherein, SOC is the ratio of the remaining charge of the energy storage capacitor to its maximum charge.

[0060] Optionally, before determining the current setpoint based on the current limit value or the current control value, the method further includes:

[0061] Based on preset power limitations, the preset constant charging and discharging power P of the energy storage capacitor is determined. SC The expression for the preset power limit condition is:

[0062]

[0063] Where T0 is the working cycle of the energy storage capacitor; T is the actual working time of the energy storage capacitor, with both the charging and discharging cycles being 0.5T; C is the capacitance value of the energy storage capacitor; 0 is the initial time, t∈(0, 0.5T); I SC0 The rated current of the energy storage capacitor is given.

[0064] Thirdly, this application provides an energy storage system, including: an energy storage capacitor and a control system for the energy storage system provided in any embodiment of this application.

[0065] Fourthly, this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the control method of the energy storage system provided in any embodiment of this application.

[0066] The control system, method, and energy storage system provided in this application embodiment offer a constant power control strategy for energy storage systems based on energy storage capacitors. A mode selection module determines the operating mode and given voltage value of the energy storage capacitor. A voltage closed-loop control module implements closed-loop control of the traction network voltage to achieve the desired given voltage value. Simultaneously, the voltage closed-loop control module outputs a current control value. Based on a power control module, the ratio of a preset constant charging / discharging power to the terminal voltage across the energy storage capacitor is used to obtain a current limit value for the energy storage capacitor. Based on this current limit value or current control value, a current setpoint is determined, and a current closed-loop control module implements closed-loop control of the energy storage capacitor's current to achieve the desired current setpoint. A modulation wave is obtained based on the current deviation value. A PWM modulation module determines the control pulse for the energy storage capacitor's converter based on the modulation wave output by the current closed-loop control module, thereby controlling the charging and discharging of the energy storage capacitor. The technical solution of this application embodiment realizes constant power control of the energy storage capacitor, so that the energy storage capacitor can be charged and discharged with a large power during the train starting and braking stages, making the power curve of the energy storage capacitor more in line with the electric braking characteristics of the train, and improving the voltage stabilization performance and energy saving effect of the energy storage capacitor. Attached Figure Description

[0067] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0068] Figure 1 An application scenario diagram provided for an embodiment of this application;

[0069] Figure 2 This is a schematic diagram of the control system of an energy storage system provided in one embodiment of the present application;

[0070] Figure 3 A schematic diagram of the control system of an energy storage system provided in another embodiment of this application;

[0071] Figure 4 This application Figure 3 The illustrated embodiment provides a structural schematic diagram of a supercapacitor energy storage system and its control system;

[0072] Figure 5A flowchart illustrating a control method for an energy storage system provided in one embodiment of this application;

[0073] Figure 6 This is a schematic diagram of the structure of an energy storage system provided in one embodiment of this application;

[0074] Figure 7 This is a schematic diagram of the structure of an electronic device provided in one embodiment of this application.

[0075] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0076] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0077] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0078] The application scenarios of the embodiments of this application are explained below:

[0079] Figure 1 An application scenario diagram provided for an embodiment of this application, such as Figure 1As shown, the energy storage system provided in this application embodiment is an energy storage system including an energy storage capacitor, such as a supercapacitor, specifically a supercapacitor energy storage system for rail transit. Under the control of the traction power supply network 120, the train operates on a designated track 130 according to a preset mode. The operation of the train 110 mainly includes three stages: the starting stage, the constant speed driving stage, and the braking stage. In the starting stage, the typical characteristics of the train 110 are: initially, the traction power is relatively small, and as the speed of the train 110 increases, the traction power gradually increases; in the braking stage, the typical characteristics of the train 110 are: initially, the braking power is very large, and as the speed of the train decreases, the braking power gradually decreases. To improve energy recovery efficiency and ensure voltage stability during train operation at each stage, an energy storage system 140 needs to be designed to recover braking energy during train braking, improve energy utilization, and provide reliable traction force for the train during startup to ensure smooth train startup. In order to improve the performance of the energy storage system 140, a corresponding control system 150 needs to be designed for it, so as to control the charging and discharging processes of the energy storage system 140, realize the recovery of braking energy and provide reliable traction for the train.

[0080] However, existing energy storage systems employ current-limiting control. During train traction, the supercapacitor provides traction energy to the train at a constant current; during braking, it absorbs braking energy at a constant current. Under this current-limiting control strategy, the power characteristics of the energy storage capacitor change in the opposite direction to the train's power characteristics, failing to achieve effective voltage stabilization and energy saving.

[0081] The main concept of the control system for the energy storage system provided in this application is: based on a constant power limiting control method, a constant power control strategy is provided for the energy storage system, so that the energy storage capacitor can charge and discharge with a larger charging and discharging power, thereby improving the voltage regulation characteristics and energy utilization rate of the energy storage system.

[0082] Figure 2 This is a schematic diagram of the control system of an energy storage system provided in one embodiment of this application, as shown below. Figure 2 As shown, the control system of the energy storage system provided in this embodiment includes: a mode selection module 210, a voltage closed-loop control module 220, a power control module 230, a current closed-loop control module 240, and a PWM modulation module 250.

[0083] The system includes a mode selection module 210 for determining the operating mode and voltage setpoint of the energy storage capacitor based on the grid voltage of the traction power supply network; a voltage closed-loop control module 220 for calculating the voltage deviation between the voltage setpoint and the grid voltage, and determining the current control value based on the voltage deviation; a power control module 230 for determining the current setpoint based on a current limit value or the current control value, wherein the current limit value is the ratio of the preset constant charging and discharging power of the energy storage capacitor to the terminal voltage of the energy storage capacitor; a current closed-loop control module 240 for determining the current deviation based on the current setpoint and the current value of the energy storage capacitor, and obtaining a modulation wave based on the current deviation; and a PWM modulation module 250 for determining a converter control pulse based on the modulation wave, so as to control the charging and discharging current of the energy storage capacitor in the operating mode according to the control pulse.

[0084] The energy storage capacitor in this energy storage system can be a supercapacitor. A supercapacitor, also known as an electrochemical capacitor, is a power source with special properties, falling between traditional capacitors and batteries. It primarily stores energy through the electric double layer and redox capacitance. No chemical reaction occurs during its energy storage process, and the process is reversible, allowing for hundreds of thousands of charge-discharge cycles. The energy storage capacitor can consist of m×n supercapacitor modules, where m and n are the number of series and parallel connections, respectively. Each supercapacitor module has the same power output. This energy storage system can be used in rail transit, such as the energy storage system of subway trains. The grid voltage of the traction power supply network can be 1500V or other voltage values, determined based on the actual situation. The voltage setpoint can be pre-stored in the mode selection module.

[0085] Specifically, the various modules of this control system can be integrated into a single chip or a single integrated circuit. The mode selection module can be a mode selection circuit composed of comparators; the voltage closed-loop control module can be a voltage closed-loop control circuit composed of a voltage deviation calculation circuit and a first PI controller; the power control module can be a power control circuit; and the current closed-loop control module can be a current closed-loop control circuit composed of a current deviation calculation circuit and a second PI controller.

[0086] Specifically, the mode selection module 210 can be composed of comparators to compare the collected grid voltage of the traction power supply network with preset voltage thresholds, thereby determining the working mode of the energy storage capacitor and the voltage setpoint of the voltage closed-loop control module 220 based on the comparison results.

[0087] Optionally, the mode selection module 210 is specifically used for:

[0088] When the grid voltage is greater than the charging voltage threshold of the energy storage capacitor and less than the maximum allowable grid voltage, the operating mode of the energy storage capacitor is determined to be the charging mode, and the voltage setpoint is the charging setpoint; when the grid voltage is greater than the minimum allowable grid voltage and less than the discharging voltage threshold of the energy storage capacitor, the operating mode of the energy storage capacitor is determined to be the discharging mode, and the voltage setpoint is the discharging setpoint.

[0089] Among these, the maximum permissible grid voltage refers to the maximum grid voltage allowed by the traction power supply network, while the minimum permissible grid voltage is the minimum grid voltage. The charging voltage threshold is the minimum voltage value of the energy storage capacitor in charging mode. The discharging voltage threshold is the maximum voltage value of the energy storage capacitor in discharging mode.

[0090] Specifically, when the train is braking, the mode selection module 210 outputs the charging mode; when the train is traction or starting, the mode selection module 210 outputs the discharging mode; and when the train is traveling at a constant speed, the mode selection module 210 outputs the standby mode, in which the energy storage capacitor neither discharges nor charges.

[0091] Specifically, the mode selection module 210 monitors the grid voltage of the traction power supply network in real time and determines the corresponding operating mode and voltage setpoint based on the range of the currently collected grid voltage. If the grid voltage U dc Located in [U char U max If the range is specified, the operating mode is determined to be charging mode, and the voltage setpoint is U. char_ref If the grid voltage U dc In (U) dis U char If the grid voltage U is within a certain range, the operating mode is determined to be standby mode, in which case the energy storage capacitor neither charges nor discharges; if the grid voltage U dc In [U] min U dis If the range is specified, the operating mode is determined to be discharge mode, and the voltage setpoint is U. dis_ref , among which, U max To maximize the allowable network voltage, U char U is the charging voltage threshold. dis U is the discharge voltage threshold. min This is the minimum permissible voltage.

[0092] For example, the energy storage system could be a 1MW supercapacitor-based energy storage system operating at 1500V grid voltage, with a maximum permissible grid voltage U. max It can be 1900V, charging voltage threshold U char It can be 1700V, discharge voltage threshold Udis It can be 1600V, and the minimum allowable mains voltage can be 1000V.

[0093] Specifically, the voltage closed-loop control module 220 is a closed-loop control circuit that receives the voltage setpoint from the mode selection module 210 and, based on the difference between the voltage setpoint and the grid voltage, implements closed-loop control of the grid voltage to ensure that the grid voltage tracks the voltage setpoint and stabilizes the grid voltage. The voltage closed-loop control module 220 can consist of a differential circuit and a controller. The differential circuit calculates the difference between the grid voltage and the voltage setpoint. The controller, which can be a PI controller, PID controller, or other controller, determines the corresponding control quantity based on the difference between the grid voltage and the voltage setpoint, i.e., the current control value I of the subsequent power control module 230. ref This is to control the grid voltage to remain near the given voltage value and achieve a stable state.

[0094] Specifically, the power control module 230 is used to receive the current control value I from the voltage closed-loop control module 220. ref And determine the current limit value I. SC_lim According to the current control value I ref Or current limit value I SC_lim Determine the current setpoint I of the current closed-loop control module 240 ref * Among them, current limit I SC_lim The expression is: I SC_lim =P SC_lim / U SC , among which, U SC P is the terminal voltage across the energy storage capacitor. SC_lim The preset constant charging and discharging power for the energy storage capacitor is a preset fixed value.

[0095] Furthermore, the preset constant charging and discharging power P SC_lim The value can be set manually or determined automatically based on the performance parameters of the energy storage capacitor, such as the internal resistance and capacitance value of the energy storage capacitor.

[0096] Optionally, the power control module 230 is specifically used for:

[0097] When the voltage deviation value is less than the preset voltage deviation threshold, the current setpoint is determined according to the current control value based on the first current setpoint relationship; when the voltage deviation value is greater than the preset voltage deviation threshold, the current limit value is determined as the current setpoint.

[0098] The preset voltage deviation threshold can be 50V, 40V, 30V or other values, which can be set by the user or by default.

[0099] Optionally, the power control module 230 is specifically used for:

[0100] When the current control value is less than the maximum value of the current limit value, the current setpoint is determined based on the first current setpoint relationship and the current control value; when the current control value is greater than or equal to the maximum value of the current limit value, the current limit value is determined as the current setpoint value.

[0101] The expression for the current limiting value is: I SC_lim (t)=P SC_lim / U SC (t), P SC_lim For the preset constant charging and discharging power, U SC (t) represents the terminal voltage of the energy storage capacitor at time t.

[0102] Optionally, the relationship for the first current setpoint is:

[0103]

[0104] I lim_max =P SC_lim / U SC_min

[0105] Among them, U SC_min P is the minimum permissible terminal voltage of the energy storage capacitor. SC_lim The preset constant charging and discharging power; U SC (t) is the terminal voltage of the energy storage capacitor at time t; I ref (t) represents the current control value at time t; I lim_max Current limit value I SC_lim The maximum value of (t); I ref * (t) represents the current given value at time t.

[0106] Specifically, I lim_max It can be 900A, 1000A, 1100A or other values.

[0107] It should be noted that for any function in this application, the independent variable t can be omitted for ease of description.

[0108] Specifically, the current setpoint I ref * The expression is:

[0109]

[0110] Or:

[0111]

[0112] Among them, I lim_max =P SC_lim / U SC_min ΔU is the maximum value of the current limit; ΔU is the voltage deviation value; ΔU th The preset voltage deviation threshold is defined as follows.

[0113] Specifically, when the voltage deviation is larger, ΔU > ΔU th When this occurs, it indicates that the grid voltage differs significantly from the voltage setpoint, and the current control value I is used. ref This allows the charging and discharging power of the energy storage capacitor to be kept constant at a preset constant charging and discharging power P. SC When the voltage deviation is small, ΔU ≤ ΔU th When the voltage is close to the grid voltage setpoint, the power requirement for the energy storage system is relatively small. To avoid control overshoot, the control amplitude needs to be reduced. Therefore, the current control value I of the energy storage capacitor is adopted. ref With the maximum allowable current I lim_max The ratio is set to a coefficient less than 1 to reduce the current control quantity, thereby avoiding control overshoot and improving control accuracy.

[0114] Specifically, the current closed-loop control module 240 receives the current setpoint I from the power control module 230. ref * Simultaneously, the charging and discharging current I of the energy storage capacitor is monitored in real time. SC The difference between the two values ​​is calculated, which can be implemented using a differential circuit to obtain the current deviation value. Based on a current controller, such as a PI controller, PID controller, or other types of controller, the modulation wave of the PWM modulation module is determined according to this current deviation value to achieve closed-loop control of the charging and discharging current of the energy storage capacitor. This ensures that the current tracks the given current value and remains stable. The modulation wave of the PWM modulation module 250 is determined based on the current deviation value. Then, the control pulse of the switching transistor is obtained by comparing the modulation wave output by the PWM modulation module 250 with the carrier triangular wave. Specifically, the control pulse is high when the modulation wave amplitude is greater than the triangular wave, and low when the modulation wave amplitude is less than the triangular wave. This control pulse is the control pulse of the converter for the energy storage capacitor. Based on this control pulse, the converter controls the energy storage capacitor to release electrical energy to the traction power grid at the desired power, thereby achieving voltage regulation.

[0115] The control system, method, and energy storage system provided in this application embodiment offer a constant power control strategy for energy storage systems based on energy storage capacitors. A mode selection module determines the operating mode and given voltage value of the energy storage capacitor. A voltage closed-loop control module implements closed-loop control of the traction network voltage to achieve the desired given voltage value. Simultaneously, the voltage closed-loop control module outputs a current control value. Based on a power control module, the ratio of a preset constant charging / discharging power to the terminal voltage across the energy storage capacitor is used to obtain a current limit value for the energy storage capacitor. Based on this current limit value or current control value, a current setpoint is determined, and a current closed-loop control module implements closed-loop control of the energy storage capacitor's current to achieve the desired current setpoint. A modulation wave is obtained based on the current deviation value. A PWM modulation module determines the control pulse for the energy storage capacitor's converter based on the modulation wave output by the current closed-loop control module, thereby controlling the charging and discharging of the energy storage capacitor. The technical solution of this application embodiment realizes constant power control of the energy storage capacitor, so that the energy storage capacitor can be charged and discharged with a large power during the train starting and braking stages, making the power curve of the energy storage capacitor more in line with the electric braking characteristics of the train, and improving the voltage stabilization performance and energy saving effect of the energy storage capacitor.

[0116] Figure 3 A schematic diagram of the control system of an energy storage system provided in another embodiment of this application is shown below. Figure 3 As shown, this embodiment is... Figure 2 Based on the embodiment shown, the voltage closed-loop control module 220 is further refined, and a state of charge limiting circuit and a preset power determination module are added. The control system of the energy storage system provided in this embodiment includes: a preset power determination module 300, a mode selection module 310, a voltage deviation calculation module 321, a voltage PI adjustment module 322, a power control module 330, a state of charge limiting module 340, a current closed-loop control module 350, and a PWM modulation module 360.

[0117] The preset power determination module 300 is used to determine the preset constant charging and discharging power of the energy storage capacitor based on preset power limit conditions before determining the current setpoint according to the current limit value or the current control value. The module mode selection module 310 is used to determine the operating mode of the energy storage capacitor as charging mode when the grid voltage is greater than the charging voltage threshold of the energy storage capacitor and less than the maximum allowable grid voltage, and the voltage setpoint is the charging setpoint value; when the grid voltage is greater than the minimum allowable grid voltage and less than the discharging voltage threshold of the energy storage capacitor, the operating mode of the energy storage capacitor is determined as discharging mode, and the voltage setpoint is the discharging setpoint value. The voltage deviation calculation module 321 is used to calculate the voltage deviation between the voltage setpoint value and the grid voltage. The voltage PI adjustment module 322 is used to determine the current control value according to the voltage deviation value to achieve closed-loop control of the grid voltage. The module power control module 330 is used to determine the current setpoint according to the current limit value or the current control value, wherein the current limit value is the ratio of the preset constant charging and discharging power of the energy storage capacitor to the terminal voltage of the energy storage capacitor. The state-of-charge limiting module 340 is used to set the current setpoint to 0 when the remaining charge of the energy storage capacitor is higher than a first charge threshold or lower than a second charge threshold; the module current closed-loop control module 350 is used to determine the current deviation value based on the adjusted current setpoint and the current value of the energy storage capacitor, and to obtain a modulation wave based on the current deviation value; the PWM modulation module 360 ​​is used to determine the converter control pulse based on the modulation wave, so as to control the charging and discharging current of the energy storage capacitor in the operating mode according to the control pulse.

[0118] The expression for the preset power limit condition is as follows:

[0119]

[0120] Where T0 is the working cycle of the energy storage capacitor; T is the actual working time of the energy storage capacitor, with both the charging and discharging cycles being 0.5T; C is the capacitance value of the energy storage capacitor; 0 is the initial time, t∈(0, 0.5T); I SC0 The rated current of the energy storage capacitor (intermittent operation, working time T for every T0 time, and charging and discharging time of 0.5T time).

[0121] Specifically, due to the internal resistance of the energy storage capacitor, a temperature rise occurs during its charging and discharging process, which limits the operating current of the energy storage capacitor. In order to simultaneously ensure the operating efficiency of the energy storage capacitor and avoid damage to the supercapacitor due to excessive temperature, the energy storage capacitor needs to operate intermittently. This ensures that the energy storage capacitor can meet the large charging and discharging power requirements while ensuring that the effective value of the charging and discharging current meets the temperature rise limit.

[0122] Furthermore, to avoid overheating, the energy storage capacitor operates in an intermittent mode. To ensure that the charging and discharging power of the energy storage capacitor meets the requirements, the preset power limit condition for the constant charging and discharging power is determined by the following expression:

[0123]

[0124]

[0125] I RMS ≤I SC0

[0126] Among them, R es I is the internal resistance of the energy storage capacitor; RMS The effective value of the current of the stored energy is given.

[0127] The expression for the aforementioned preset power limit condition can be obtained through reasonable derivation.

[0128] It's important to understand that the initial time can be other than 0, such as t1.

[0129] Specifically, the preset constant charging and discharging power of the energy storage capacitor can be the minimum value that satisfies the above inequality, or other suitable values, which can be determined by the actual situation.

[0130] Specifically, the actual operating time of the energy storage capacitor in charging mode and discharging mode, i.e., the charging cycle and discharging cycle T, are the same. The operating cycle T0 should be determined based on the actual circuit conditions.

[0131] For example, taking the train braking state as an example, the energy storage capacitor is working in charging mode. The energy storage system adopts an intermittent working system, working for 30 seconds (T) every 120 seconds (T0), with each charging and discharging time being 15 seconds (0.5T). Therefore, the working cycle T0 is set to 120 seconds, and the actual working time T is 30 seconds.

[0132] Specifically, the state of charge (SOC) limiting module 340 can be integrated into the module power control module 330. It is mainly used to flexibly disconnect the energy storage capacitor when its remaining charge or SOC is too high or too low, preventing overcharging or over-discharging and protecting the energy storage capacitor. This flexible disconnection also avoids impact when the energy storage system exits the traction power grid.

[0133] Specifically, the current setpoint adjustment module receives the remaining charge SOC output by the state of charge limiting module 340, and adjusts the current setpoint based on the preset setpoint adjustment formula and SOC.

[0134] Optionally, the relationship for the first current setpoint is:

[0135] I ref * (t)=(I ref (t) / I lim_max )×(P SC_lim / U SC (t))×K SOC

[0136] Wherein, when the working mode is charging mode, K SOC The expression is: When the operating mode is discharge mode, K SOC The expression is: Wherein, SOC is the ratio of the remaining charge of the energy storage capacitor to its maximum charge.

[0137] Through parameter K SOC For the current given value I ref * (t) is adjusted so that when the SOC of the energy storage capacitor is too low (less than 0.25) or too high (1), the given current value is set to 0, thereby disconnecting the energy storage capacitor from the train's traction power supply network and thus avoiding overcharging or over-discharging of the energy storage capacitor.

[0138] Of course, the above SOC thresholds are just examples. The specific values ​​can be determined based on the performance of the energy storage capacitor itself. For example, 0.25 can be replaced with 0.2, 0.15 or other values, 0.3 can be replaced with 0.4, 0.35 or other values, 0.95 can be replaced with 0.9, 0.85 or other values, and 1 can be replaced with 0.99, 0.98 or other values, etc.

[0139] For example, Figure 4 This application Figure 3 The illustrated embodiment provides a structural schematic diagram of a supercapacitor energy storage system and its control system, as shown below. Figure 4 As shown, the supercapacitor energy storage system 400 includes a traction power supply network 410, a converter 420, and a supercapacitor bank 430. The grid voltage level of the traction power supply network 410 is 1500V. The supercapacitor bank 430 is composed of 48V supercapacitor modules arranged in a 20-series-3-parallel configuration. The typical thermal resistance R of the supercapacitor module is... ca The internal resistance R of the supercapacitor module is 0.4℃ / W. esThe supercapacitor has a capacitance of 6mΩ, a capacitance C of 25F, an operating voltage range of 450V~900V (SOC: 0.25~1), an allowable operating temperature of -40℃~65℃, and a rated operating current of 760A. The control system 500 corresponding to this supercapacitor energy storage system mainly consists of three parts: a mode selection section 510, a dual closed-loop control section 520, and a PWM modulation section 530. The mode selection section 510, composed of the aforementioned module mode selection module 310, is used to determine the operating mode of the supercapacitor 430 and the given voltage value of the dual closed-loop control section 520 based on the real-time detected grid voltage. The dual closed-loop control section 520 includes a voltage outer loop section 521, a power control section 522, and a current inner loop section 523. It is used to control the modulation wave of the PWM modulation section 530 based on power control, thereby controlling the supercapacitor 430 to charge or discharge in the determined operating mode to stabilize the grid voltage. The voltage outer loop section 521, composed of the aforementioned voltage deviation calculation module 321 and voltage PI adjustment module 322, implements closed-loop control of the grid voltage based on the difference between the grid voltage feedback value (grid voltage) and the given voltage value to stabilize the grid voltage. The power control section 522, composed of the aforementioned module power control module 300, module power control module 330, and state-of-charge limiting module 340, implements a preset constant power (preset constant charging / discharging power P) to achieve a stable grid voltage. SC The power of the energy storage capacitor is controlled to obtain the current setpoint of the inner current loop section 523. The inner current loop section 523 is composed of the module current closed-loop control module 350. Based on the difference between the current feedback value (charging and discharging current of the supercapacitor 430) and the current setpoint, the closed-loop control of the current is realized to control the modulation wave of the PWM modulation section 530 (composed of PWM modulation module 360), thereby controlling the control pulse of the converter 420 of the supercapacitor 430, realizing the power control of the supercapacitor 430, thereby improving the charging and discharging power of the supercapacitor 430 to meet the operating characteristics of the train, and at the same time improving the voltage regulation performance of the supercapacitor 430.

[0140] In this embodiment, a power control-based system is provided for the energy storage system based on the energy storage capacitor. This system achieves constant power control of the energy storage capacitor, ensuring that its power characteristics match the power characteristics of the train operation, thereby improving the voltage regulation performance and energy utilization rate of the energy storage system. The dual closed-loop voltage and current control improves control stability and accuracy. By using the energy storage capacitor's own parameters, such as internal resistance, operating temperature, voltage, and current, a preset constant charging and discharging power is determined, ensuring the normal operation of the energy storage capacitor while maximizing its utilization, thus improving its efficiency and safety. Furthermore, the state-of-charge (SOC) limiting module flexibly disconnects the energy storage capacitor from the traction power supply network when its charge level is too high or too low, effectively preventing overcharging or over-discharging and extending the capacitor's lifespan.

[0141] Figure 5 This is a flowchart illustrating a control method for an energy storage system according to an embodiment of this application. This control method can be executed by the energy storage system's control system or by a processor. Figure 5 As shown, the control method for the energy storage system provided in this embodiment includes the following steps:

[0142] Step S501: The operating mode and voltage setpoint of the energy storage capacitor of the energy storage system are determined by the mode selection module based on the grid voltage of the traction power supply network.

[0143] Step S502: The voltage deviation between the voltage setpoint and the grid voltage is calculated via the voltage closed-loop control module, and the current control value is determined based on the voltage deviation value.

[0144] Step S503: The current setpoint is determined by the power control module based on the current limit value or the current control value.

[0145] The current limit value is the ratio of the preset constant charging and discharging power of the energy storage capacitor to the terminal voltage of the energy storage capacitor.

[0146] Step S504: The current deviation value is determined by the current closed-loop control module based on the current setpoint and the current value of the energy storage capacitor, and the modulation wave is obtained based on the current deviation value.

[0147] Step S505: The converter control pulse is determined by the PWM modulation module based on the modulation wave, so as to control the charging and discharging current of the energy storage capacitor in the operating mode according to the control pulse.

[0148] Optionally, determining the operating mode and voltage setpoint of the energy storage capacitor of the energy storage system based on the grid voltage of the traction power supply network includes:

[0149] When the grid voltage is greater than the charging voltage threshold of the energy storage capacitor and less than the maximum allowable grid voltage, the operating mode of the energy storage capacitor is determined to be the charging mode, and the voltage setpoint is the charging setpoint; when the grid voltage is greater than the minimum allowable grid voltage and less than the discharging voltage threshold of the energy storage capacitor, the operating mode of the energy storage capacitor is determined to be the discharging mode, and the voltage setpoint is the discharging setpoint.

[0150] Optionally, the module voltage closed-loop control module includes a voltage deviation calculation module and a voltage PI regulation module. The calculation of the voltage deviation between the voltage setpoint and the grid voltage includes:

[0151] The voltage deviation calculation module calculates the voltage deviation between the voltage setpoint and the grid voltage; the step of determining the current control value based on the voltage deviation value includes: determining the current control value based on the voltage deviation value via the voltage PI adjustment module to achieve closed-loop control of the grid voltage.

[0152] Optionally, determining the current setpoint based on the current limit value or the current control value includes:

[0153] When the voltage deviation value is less than the preset voltage deviation threshold, the current setpoint is determined according to the current control value based on the first current setpoint relationship; when the voltage deviation value is greater than the preset voltage deviation threshold, the current limit value is determined as the current setpoint.

[0154] Optionally, determining the current setpoint based on the current limit value or the current control value includes:

[0155] When the current control value is less than the maximum value of the current limit value, the current setpoint is determined based on the current control value according to the first current setpoint relationship.

[0156] When the current control value is greater than or equal to the maximum value of the current limit value, the current limit value is determined as the current setpoint; wherein, the expression for the current limit value is: I SC_lim (t)=P SC_lim / U SC (t), P SC_lim For the preset constant charging and discharging power, U SC (t) represents the terminal voltage of the energy storage capacitor at time t.

[0157] Optionally, the relationship for the first current setpoint is:

[0158] I ref * (t)=(I ref (t) / I lim_max)×I SC_lim (t)

[0159] I lim_max =P SC_lim / U SC_min

[0160] Among them, U SC_min I is the minimum permissible terminal voltage of the energy storage capacitor; ref (t) represents the current control value at time t; I lim_max The current limit value I SC_lim The maximum value of (t); I ref * (t) represents the current given value at time t.

[0161] Optionally, the module power control module further includes a state of charge limiting module, and the control method further includes:

[0162] The current setpoint is set to 0 when the remaining charge of the energy storage capacitor is higher than a first charge threshold or lower than a second charge threshold, via the state of charge limiting module.

[0163] Optionally, the relationship for the first current setpoint is:

[0164] I ref * (t)=(I ref (t) / I lim_max )×(P SC_lim / U SC (t))×K SOC

[0165] Wherein, when the working mode is charging mode, K SOC The expression is: When the operating mode is discharge mode, K SOC The expression is: Wherein, SOC is the ratio of the remaining charge of the energy storage capacitor to its maximum charge.

[0166] Optionally, before determining the current setpoint based on the current limit value or the current control value, the method further includes: determining a preset constant charge / discharge power P of the energy storage capacitor based on a preset power limit condition. SC_lim The expression for the preset power limit condition is:

[0167]

[0168] Where T0 is the working cycle of the energy storage capacitor; T is the actual working time of the energy storage capacitor, with both the charging and discharging cycles being 0.5T; C is the capacitance value of the energy storage capacitor; 0 is the initial time, t∈(0, 0.5T); I SC0 The rated current of the energy storage capacitor (intermittent operation, working time T for every T0 time, and charging and discharging time of 0.5T time).

[0169] The control method for an energy storage system provided in this application provides a constant power control strategy for an energy storage system based on an energy storage capacitor. The operating mode and given voltage value of the energy storage capacitor are determined by a module mode selection module. Closed-loop control of the traction network voltage is achieved based on a module voltage closed-loop control module to reach the desired given voltage value. Simultaneously, a current control value is output via the module voltage closed-loop control module. Based on a module power control module, the current limit value of the energy storage capacitor is obtained according to the ratio of a preset constant charging / discharging power to the terminal voltage across the energy storage capacitor. A current setpoint is determined based on this current limit value or current control value, and closed-loop control of the energy storage capacitor's current is achieved via current closed-loop control to ensure the current reaches the desired current setpoint. Simultaneously, the rectifier of the energy storage capacitor is controlled according to the control signal output by the current closed-loop control module to achieve charging and discharging control of the energy storage capacitor. The technical solution of this application embodiment realizes constant power control of the energy storage capacitor, so that the energy storage capacitor can be charged and discharged with a large power during the train starting and braking stages, making the power curve of the energy storage capacitor more in line with the electric braking characteristics of the train, and improving the voltage stabilization performance and energy saving effect of the energy storage capacitor.

[0170] Figure 6 This is a schematic diagram of the structure of an energy storage system provided in one embodiment of this application, as shown below. Figure 6 As shown, the energy storage system provided in this embodiment includes: an energy storage capacitor 610 and a control system 620.

[0171] The energy storage capacitor 610 and the control system 620 are electrically connected. The energy storage capacitor 610 may be one or more supercapacitors. The control system 620 is the control system of the energy storage system provided in any embodiment of this application, used to control the power or current of charging and discharging of the energy storage capacitor 610.

[0172] Figure 7 This is a schematic diagram of the structure of an electronic device provided in one embodiment of this application, as shown below. Figure 7 As shown, the electronic device provided in this embodiment includes: a memory 710, a processor 720, and a computer program.

[0173] The computer program is stored in memory 710 and configured to be executed by processor 720 to implement this application. Figure 5The corresponding embodiment provides a control method for the energy storage system.

[0174] The memory 710 and the processor 720 are connected via a bus 730.

[0175] For relevant instructions, please refer to the corresponding text. Figure 5 The relevant descriptions and effects corresponding to the steps will be understood, and will not be elaborated on here.

[0176] One embodiment of this application provides a computer-readable storage medium having a computer program stored thereon, the computer program being executed by a processor to implement this application. Figure 5 The corresponding embodiment provides a control method for the energy storage system.

[0177] The computer-readable storage medium can be ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device, etc.

[0178] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0179] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application filed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not claimed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0180] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A control system for an energy storage system, characterized in that, The energy storage system includes an energy storage capacitor, and the control system includes: a mode selection module, a voltage closed-loop control module, a power control module, a current closed-loop control module, and a PWM modulation module. The mode selection module is used to determine the operating mode and voltage setpoint of the energy storage capacitor of the energy storage system based on the grid voltage of the traction power supply network. The voltage closed-loop control module is used to calculate the voltage deviation between the voltage setpoint and the grid voltage, and to determine the current control value based on the voltage deviation. The power control module is used to determine the current setpoint based on the current limit value or the current control value, wherein the current limit value is the ratio of the preset constant charging and discharging power of the energy storage capacitor to the terminal voltage of the energy storage capacitor. The current closed-loop control module is used to determine the current deviation value based on the current setpoint and the current value of the energy storage capacitor, and to obtain the modulation wave based on the current deviation value. The PWM modulation module is used to determine the converter control pulse according to the modulation wave, so as to control the charging and discharging current of the energy storage capacitor in the operating mode according to the control pulse; The control system further includes: A preset power determination module is used to determine a preset constant charging and discharging power of the energy storage capacitor based on a preset power limit condition before determining the current setpoint according to the current limit value or the current control value. The expression for the preset power limit condition is: in, The operating cycle of the energy storage capacitor; The actual operating time of the energy storage capacitor is 0.5 hours, with both the charging and discharging cycles being 0.5 hours. ; The capacitance value of the energy storage capacitor; At the initial moment, ; The rated current of the energy storage capacitor is... The preset constant charging and discharging power; This is the minimum permissible terminal voltage of the energy storage capacitor.

2. The control system according to claim 1, characterized in that, The power control module is specifically used for: When the current control value is less than the maximum value of the current limit value, the current setpoint is determined based on the current control value according to the first current setpoint relationship. When the current control value is greater than or equal to the maximum value of the current limit value, the current limit value is determined as the current setpoint value; The expression for the current limit value is as follows: , For the preset constant charging and discharging power, for The terminal voltage of the energy storage capacitor at that time.

3. The control system according to claim 2, characterized in that, The first current setpoint relationship is: in, This is the minimum permissible terminal voltage of the energy storage capacitor; for The current control value at that time; The current limit value The maximum value; for The given current value at time t.

4. The control system according to claim 2, characterized in that, The power control module also includes a state-of-charge limiting module, used for: When the remaining charge of the energy storage capacitor is higher than the first charge threshold or lower than the second charge threshold, the current setpoint is set to 0.

5. The control system according to claim 4, characterized in that, The first current setpoint relationship is: When the operating mode is charging mode, The expression is: When the operating mode is discharge mode, The expression is: Wherein, SOC is the ratio of the remaining charge of the energy storage capacitor to its maximum charge. for The given current value at time; for The current control value at that time; Current limit value The maximum value; The preset constant charging and discharging power; for The terminal voltage of the energy storage capacitor at time t.

6. The control system according to claim 1, characterized in that, The mode selection module is specifically used for: When the grid voltage is greater than the charging voltage threshold of the energy storage capacitor but less than the maximum allowable grid voltage, the operating mode of the energy storage capacitor is determined to be the charging mode, and the voltage setpoint is the charging setpoint. When the grid voltage is greater than the minimum allowable grid voltage and less than the discharge voltage threshold of the energy storage capacitor, the operating mode of the energy storage capacitor is determined to be the discharge mode, and the voltage setpoint is the discharge setpoint.

7. The control system according to claim 1, characterized in that, The voltage closed-loop control module includes a voltage deviation calculation module and a voltage PI adjustment module; The voltage deviation calculation module is used to calculate the voltage deviation between the voltage setpoint and the grid voltage. The voltage PI regulation module is used to determine the current control value based on the voltage deviation value, so as to realize closed-loop control of the grid voltage.

8. A control method for an energy storage system, characterized in that, The energy storage system includes an energy storage capacitor, and the method includes: The operating mode and voltage setpoint of the energy storage capacitor of the energy storage system are determined by the mode selection module based on the grid voltage of the traction power supply network. The voltage deviation between the voltage setpoint and the grid voltage is calculated via the voltage closed-loop control module, and the current control value is determined based on the voltage deviation. The current setpoint is determined by the power control module based on the current limit value or the current control value, wherein the current limit value is the ratio of the preset constant charging and discharging power of the energy storage capacitor to the terminal voltage of the energy storage capacitor. The current deviation value is determined based on the current setpoint and the current value of the energy storage capacitor via the current closed-loop control module, and the modulation wave is obtained based on the current deviation value. The converter control pulse is determined based on the modulation wave via the PWM modulation module, and the charging and discharging current of the energy storage capacitor in the operating mode is controlled according to the control pulse. Before determining the current setpoint based on the current limit value or the current control value, the preset power determination module determines the preset charging and discharging constant power of the energy storage capacitor based on the preset power limit condition. The expression for the preset power limit condition is as follows: in, The operating cycle of the energy storage capacitor; The actual operating time of the energy storage capacitor, with both the charging and discharging cycles being [missing information]. ; The capacitance value of the energy storage capacitor; At the initial moment, ; The rated current of the energy storage capacitor is... The preset constant charging and discharging power; This is the minimum permissible terminal voltage of the energy storage capacitor.

9. An energy storage system, characterized in that, It includes an energy storage capacitor and a control system as described in any one of claims 1-7.

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