CN-122014379-A - Composite energy storage system utilizing waste mine gravity and compressed air and control method

CN122014379ACN 122014379 ACN122014379 ACN 122014379ACN-122014379-A

Abstract

The invention provides a composite energy storage system utilizing gravity and compressed air of a waste mine and a control method, wherein the system comprises a waste mine vertical shaft, a giant piston assembly, a compressed air energy storage assembly, an electric power conversion assembly and a controller, the giant piston assembly is arranged in the waste mine vertical shaft and can reciprocate along the vertical direction, the giant piston assembly comprises a counterweight body, a piston rod and a sealing assembly, the giant piston assembly divides the waste mine vertical shaft into an upper cavity and a lower air storage cavity, the piston rod is connected with and supports the counterweight body, and the sealing assembly is arranged between the counterweight body and the inner wall of the waste mine vertical shaft.

Inventors

MA XIN
KONG LINGQI
HUANG PENG
JI JIE
You Benhong
HUANG HUI
BAI QIUCHAN
DING ZUJUN
LIU BAOLIAN

Assignees

淮阴工学院

Dates

Publication Date: 20260512
Application Date: 20260414

Claims (10)

1. The composite energy storage system utilizing the gravity and the compressed air of the abandoned mine is characterized by comprising a vertical shaft of the abandoned mine, a giant piston assembly, a compressed air energy storage assembly, an electric power conversion assembly and a controller; the giant piston assembly is arranged in the vertical shaft of the abandoned mine and can reciprocate along the vertical direction; The giant piston assembly comprises a counterweight body, a piston rod and a sealing assembly, and divides the vertical shaft of the abandoned mine into an upper cavity and a lower gas storage cavity; the sealing component is used as a physical carrier with double energy storage functions, so that the coupling storage and release of gravitational potential energy and compressed air energy are realized; The compressed air energy storage assembly is communicated with the lower gas storage cavity and comprises a compressor, a gas storage unit, an expander and a valve bank, wherein the compressor is used for pressing air into the gas storage unit during charging, the expander is used for driving high-pressure air to generate electricity during discharging, the valve bank is connected between an inlet of the expander and the gas storage unit and is used for adjusting the flow rate and the flow direction of gas so as to realize energy storage and release control; The power conversion assembly is connected with the giant piston assembly and the compressed air energy storage assembly and comprises a reversible motor or a generator and a power conversion unit, wherein the reversible motor or the generator is an electric energy and mechanical energy bidirectional conversion device, the power conversion unit is an electric energy conversion and control system for realizing electric network electrical interface, power regulation and protection, and the reversible motor or the generator is electrically connected with the power conversion unit to jointly form the power conversion assembly; The controller is electrically connected with the displacement sensor, the pressure sensor, the flow sensor, the power sensor, the vibration sensor and the stress sensor respectively.
2. The system of claim 1, wherein the controller is configured to: Constructing a unified state vector of the composite energy storage system based on multisource operation signals acquired by the displacement sensor, the pressure sensor, the flow sensor, the power sensor, the vibration sensor and the stress sensor; The friction state, the leakage state, the sealing attenuation state and the coupling lag state between the gravity energy storage branch and the compressed air energy storage branch of the composite energy storage system are identified on line according to the unified state vector, wherein the huge piston component and the relevant part which is matched with the huge piston component to realize the lifting of the piston and the bidirectional conversion of mechanical energy and electric energy form the gravity energy storage branch; according to the online identification result and the current operation working condition, carrying out layered cooperative control on the gravity energy storage branch and the compressed air energy storage branch so as to determine a piston operation control amount, a compressor operation control amount, a valve group opening control amount and an expander output control amount; and in the processes of charge and discharge switching, gravity energy storage branch and compressed air energy storage branch switching and operation mode switching, the pressure change rate of the gas storage cavity, the piston speed change rate and the output torque change rate of the power conversion component are subjected to joint constraint so as to inhibit system impact and output power fluctuation.
3. The system of claim 2, wherein the unified state vector comprises one or more of piston displacement, piston velocity, reservoir pressure, gas flow, system output power, output torque, structural vibration characteristics, and structural stress characteristics.
4. The system of claim 3, wherein the on-line identification of the friction state, the leakage state, the seal decay state, and the coupling hysteresis state between the gravitational energy storage branch and the compressed air energy storage branch of the composite energy storage system based on the unified state vector comprises: Identifying the variable quantity of the running resistance of the piston according to the dynamic relation between the displacement of the piston and the pressure of the gas storage cavity; identifying a leakage trend according to the deviation between the pressure change of the gas storage cavity and the gas flow change; identifying a sealing attenuation state according to the vibration characteristic quantity and the stress characteristic quantity; identifying a coupling hysteresis state according to time deviation between the gravity energy storage branch instruction response and the compressed air energy storage branch instruction response; and identifying the coupling hysteresis state according to the deviation between the time when the gravity energy storage branch reaches the preset response amplitude after receiving the control instruction and the time when the compressed air energy storage branch reaches the preset response amplitude after receiving the control instruction.
5. The system of claim 4, wherein the operating conditions include one or more of a frequency modulation condition, a peak clipping and valley filling condition, a steady output condition, a standby condition, and a protection condition, and the controller determines the current operating condition based on grid load demand, system energy storage status, and on-line identification results.
6. The system of claim 5, wherein the hierarchical cooperative control comprises: the upper layer mode decision is used for identifying the current operation condition and determining a control target; The middle-layer power distribution is used for determining the power bearing proportion of the gravity energy storage branch and the compressed air energy storage branch according to the control target, the friction state, the leakage state, the sealing attenuation state and the coupling hysteresis state; And the lower layer is used for executing control and generating a piston lifting speed instruction, a compressor start-stop instruction, a valve group opening instruction and an expander adjusting instruction according to the power bearing proportion.
7. The system of claim 6, wherein the joint constraints implemented by the controller during a handoff include: setting an upper threshold value for the pressure change rate of the gas storage cavity; setting an upper threshold for the rate of change of the piston speed; setting an upper threshold for a rate of change of output torque of the power conversion assembly; And when any upper threshold is triggered, the power regulation rate of the corresponding branch circuit is reduced.
8. The system of claim 7, wherein the controller is further configured to evaluate a system health condition based on the vibration signature, the structural stress signature, the leakage trend, and the seal attenuation condition, and to perform derating, speed limit control, pressure limit control, and protection shutdown control when the health condition is below a preset threshold.
9. A control method for the system according to any one of claims 1 to 8, characterized by comprising the steps of: s1, acquiring multisource operation signals of piston displacement, gas storage cavity pressure, gas flow, system output power, output torque, structural vibration and structural stress; step S2, performing time synchronization processing on the multi-source operation signals, and constructing a unified state vector of the system, wherein the unified state vector is expressed as follows: , Wherein, the For the moment of time Is a system unified state vector of (1); for the moment of time Piston displacement; for the moment of time Piston speed; for the moment of time The pressure of the air storage cavity; For the moment of time A gas flow rate; for the moment of time System output power; for the moment of time Outputting torque; for the moment of time A structural vibration characteristic quantity; for the moment of time Structural stress feature; T represents a transpose; s3, carrying out on-line identification on the friction state, the leakage state, the sealing attenuation state and the coupling hysteresis state between the gravity energy storage branch and the compressed air energy storage branch of the composite energy storage system according to the unified state vector; s4, identifying the current operation condition according to the power grid load demand, the system energy storage state and the online identification result; s5, determining the power bearing proportion of the gravity energy storage branch and the compressed air energy storage branch in a layering manner according to the current operation condition and the online identification result, and generating a piston operation control quantity, a compressor operation control quantity, a valve group opening control quantity and an expander output control quantity; s6, in the processes of charge and discharge switching, gravity energy storage branch and compressed air energy storage branch switching and operation mode switching, the pressure change rate of the gas storage cavity, the piston speed change rate and the output torque change rate are subjected to joint constraint so as to inhibit system impact and output power fluctuation; and S7, executing derating operation, speed limiting control, pressure limiting control and protection shutdown control when the health state is detected to be lower than a preset threshold value.
10. The method according to claim 9, wherein in step S3, the on-line identification of the leakage state includes determining a leakage trend parameter according to a deviation between an actual variation of the gas storage cavity pressure and a theoretical variation of the pressure calculated based on the gas flow, expressed as: , Wherein, the For the moment of time Is a leakage trend parameter of (1); is the time interval between adjacent sampling moments; the theoretical pressure value at the next moment is calculated according to the gas flow and the balance model; the pressure value of the gas storage cavity is actually measured at the next moment; The controller identifies the running resistance of the piston according to the kinematic state of the piston and the pressure states of the upper cavity and the lower cavity, and the equivalent running resistance of the piston is expressed as: , Wherein, the The equivalent running resistance of the piston at the moment k; is the total mass of the giant piston assembly and the counterweight body; is the acceleration of the piston; And The pressure of the upper cavity and the pressure of the lower gas storage cavity of the piston are respectively; an effective compression area of the piston; gravitational acceleration; The controller identifies the coupling hysteresis state of the double branches, and the coupling hysteresis parameters are expressed as: , Wherein, the Is the coupling lag time of the double branch; For the time corresponding to the preset response amplitude of the compressed air energy storage branch after the control instruction is received, The time corresponding to the preset response amplitude is reached after the gravity energy storage branch receives the control instruction; in step S5, the controller performs layered power distribution on the gravity energy storage branch and the compressed air energy storage branch according to the system target output power and the online identification result, where the dual-branch power distribution is expressed as: , , Wherein, the The power born by the gravity energy storage branch at the moment k; The power born by the compressed air energy storage branch at the moment k; Outputting power for a system target; For dynamically distributing coefficients and satisfy ; Dynamic allocation coefficient The calculation formula is as follows: , Wherein, the The energy storage state is the energy storage state of the compressed air energy storage branch; An energy storage state of the gravity energy storage branch; A preset allocation function is set; In step S6, the joint constraint comprises the following steps of: , Wherein, the A pressure change rate threshold of the gas storage cavity; is the piston speed change rate threshold; D represents differentiation for the output torque change rate threshold; When (when) 、 Or (b) When any parameter reaches a corresponding upper threshold, the controller reduces the power regulation rate of the corresponding branch circuit and delays the power increasing or decreasing action of the other branch circuit so as to realize smooth transition in the switching process.

Description

Composite energy storage system utilizing waste mine gravity and compressed air and control method Technical Field The invention relates to the technical field of energy storage, in particular to a composite energy storage system utilizing waste mine gravity and compressed air and a control method. Background With the continuous rising of the proportion of intermittent renewable energy sources such as wind energy, solar energy and the like in an electric power system, the power grid has increasingly urgent demands on large-scale, long-term and high-reliability energy storage technologies. The current mainstream large-scale energy storage technology, such as pumped storage and compressed air energy storage, has specific requirements on geographic conditions, and has the problems of limited site selection, long construction period, large initial investment and the like. On the other hand, along with the exhaustion of mineral resources, a large number of abandoned mines and shafts are idle, not only the land is occupied, but also certain potential safety hazards exist, and huge underground space and existing shaft structures are not effectively utilized. In the prior art, gravity energy storage is an emerging technology for storing/releasing energy by lifting and lowering weights in a shaft, but the energy density of single gravity energy storage is relatively limited. Compressed Air Energy Storage (CAES) is dependent on a large underground cave to store high-pressure air, and has severe requirements on geological conditions. Although the combination of gravity energy storage and compressed air energy storage is envisaged, the existing scheme is generally a functionally simple superposition, the system structure is loose, the deep coupling of the core mechanical components and the underground space cannot be realized, and the energy storage density of unit space and the overall system efficiency still have a large improvement space. In addition, the existing system generally lacks intelligent regulation and control capability linked with the real-time state of the power grid and the electric power market signal, and has insufficient economy and operation flexibility. Disclosure of Invention The invention aims to solve the problems that in the existing waste mine gravity-compressed air composite energy storage system, a strong coupling relation exists among a piston motion state, a gas storage cavity pressure state and a mechanical structure state in the operation process of the system, friction resistance, leakage degree and sealing attenuation degree are dynamically changed along with operation working conditions, so that the actual state of the system is difficult to be accurately reflected by a traditional fixed parameter control mode, dynamic response speeds of a gravity energy storage branch and a compressed air energy storage branch are different, abrupt change of the gas storage cavity pressure, fluctuation of the piston speed and oscillation of output torque are easily caused in the charging and discharging switching, double-branch power switching and operation mode switching processes, and the operation stability and the service life of the system are influenced. The system comprises a waste mine vertical shaft, a giant piston assembly, a compressed air energy storage assembly, a power conversion assembly and a controller; the giant piston assembly is arranged in the vertical shaft of the abandoned mine and can reciprocate along the vertical direction; The giant piston assembly comprises a counterweight body, a piston rod and a sealing assembly, and divides the vertical shaft of the abandoned mine into an upper cavity and a lower gas storage cavity; the sealing component is used as a physical carrier with double energy storage functions, so that the coupling storage and release of gravitational potential energy and compressed air energy are realized; The compressed air energy storage assembly is communicated with the lower gas storage cavity and comprises a compressor, a gas storage unit, an expander and a valve bank, wherein the compressor is used for pressing air into the gas storage unit during charging, the expander is used for driving high-pressure air to generate electricity during discharging, the valve bank is connected between an inlet of the expander and the gas storage unit and is used for adjusting the flow rate and the flow direction of gas so as to realize energy storage and release control; The power conversion assembly is connected with the giant piston assembly and the compressed air energy storage assembly and comprises a reversible motor or a generator and a power conversion unit, wherein the reversible motor or the generator is an electric energy and mechanical energy bidirectional conversion device, the power conversion unit is an electric energy conversion and control system for realizing electric network electrical interface, power regulation and protection, and the reversible m