An energy hub system based on pumped compressed air energy storage and a method of operating the same

Abstract

This invention discloses an energy hub system based on pumped compressed air energy storage and its operation method. The system includes an upper reservoir, a gas-water co-containment chamber, a water pipeline, an air compressor, an expander, a first heat exchanger, a second heat exchanger, a high-temperature heat storage tank, and a low-temperature heat storage tank. The gas-water co-containment chamber is a closed structure, connected to the upper reservoir at a higher elevation via the water pipeline. The air compressor outlet is connected to the gas-water co-containment chamber via the first heat exchanger, and the expander inlet is connected to the second heat exchanger, with the outlet exhaust directly supplying cooling. This invention utilizes the elevation difference between the upper and lower reservoirs to achieve deep coupling of hydraulic potential energy and compressed air potential energy, collaboratively completing the production and supply of electricity, heat, and cooling energy flows within a single process. The operation method constructs a two-stage robust optimization model considering both source and load uncertainties, and solves it using the Benders decomposition method, obtaining a collaborative optimization operation strategy immune to uncertainties, thus improving the economy, robustness, and overall energy efficiency of the energy hub.

Description

Technical Field

[0001] This invention belongs to the field of new energy technology, specifically relating to an energy hub system based on pumped compressed air energy storage and its operation method. Background Technology

[0002] Industrial parks, as core carriers of industrial agglomeration, have high energy intensity and load density, and their production processes and building environments typically require the simultaneous supply of electricity, heat, and cooling. With the advancement of industrial upgrading, the demand for multiple energy sources, including cooling, heating, and electricity, in industrial parks is becoming increasingly prominent, with various energy sources exhibiting strong volatility and complex coupling relationships over time. The traditional independent energy supply model of "electricity relying on the power grid, heating relying on boilers, and cooling relying on electric refrigeration" is inefficient and has high carbon emissions, making it difficult to meet the requirements of clean, low-carbon, safe, and efficient energy use. Energy hubs, as systems integrating multiple energy inputs, conversions, and storage, can achieve synergistic complementarity and optimized allocation of electricity, heat, cooling, and gas, providing an effective technological path to improve the overall energy efficiency and renewable energy absorption capacity of industrial parks. Within energy hubs, energy storage is a key flexible resource for smoothing load fluctuations and regulating the spatiotemporal distribution of energy.

[0003] Currently, energy storage technologies used in industrial parks mainly include electrochemical energy storage, pumped hydro storage, and compressed air energy storage. Electrochemical energy storage offers fast response, but has limited lifespan, safety risks, and high life-cycle costs. Pumped hydro storage technology is mature, but site selection heavily relies on natural elevation differences and water sources, and functionally, it can only charge and discharge electricity, unable to directly meet cooling and heating loads. Conventional compressed air energy storage, while having a long lifespan and large capacity, often requires large-scale salt caverns or underground caverns as storage chambers, and the large amount of heat generated during compression is often directly dissipated, while the expansion process requires external heat sources, resulting in energy quality loss and ineffective utilization of cooling capacity. Even with advanced adiabatic compressed air energy storage recovering compression heat to some extent, its output is still limited to electricity and cannot directly provide the required heat and cooling energy to industrial parks. Converting these energy storage systems into multi-energy supply systems often requires additional configuration of heat pumps, boilers, or absorption chillers, leading to system complexity and increased investment.

[0004] Pumped compressed air (PCO) energy storage systems utilize upper and lower reservoirs with elevation differences and connecting channels to deeply couple hydraulic potential energy with compressed air potential energy. This enables constant or near-constant pressure gas storage, offering advantages such as high energy density and relatively flexible geographical adaptability. More importantly, this type of energy storage naturally generates high-grade compression heat and expansion cold energy during charging and discharging. During the energy storage phase, the high-temperature gas discharged from the air compressor releases a large amount of heat energy through a heat exchanger, which can supply hot water or steam to the centralized heating network of the industrial park. During the energy release phase, the temperature of the high-pressure air drops significantly after expanding and performing work, and the resulting low-temperature exhaust gas cold energy can directly meet the cooling load demand. Therefore, systems based on pumped compressed air energy storage are highly suitable for building energy hubs in industrial parks, achieving multi-energy supply of cooling, heating, and electricity through a single main unit, reducing redundant equipment configuration, and improving overall energy utilization and power supply reliability.

[0005] However, there is a general lack of optimized operation methods specifically for such pumped compressed air energy storage multi-energy supply hubs, making it difficult to fully realize their potential in actual industrial park scenarios. On the one hand, existing optimization scheduling research mostly focuses on electrochemical energy storage, micro gas turbines, heat pumps, or standalone compressed air energy storage, failing to simultaneously characterize the strong nonlinear coupling relationship between water pumps / turbines and air compressors / expanders under varying head conditions with hot water storage tanks and low-temperature thermal storage tanks. Furthermore, it fails to incorporate the temperature grade and utilization period of compression heat and expansion cold energy with the dynamic matching of industrial park heating and cooling loads into a unified optimization framework. On the other hand, industrial park heating, cooling, and electricity loads exhibit multi-timescale fluctuations and significant impacts on production plans. Electricity prices and renewable energy output also vary over time. Conventional heuristic scheduling or optimization methods focused solely on power balance are insufficient to achieve the lowest overall cost or highest energy efficiency for heating, cooling, and electricity multi-energy flow while ensuring reliable power supply. Because of the lack of an operational model that can accurately describe the constraints of the height difference between the upper and lower reservoirs, the constant pressure operation mode, the switching between multiple operating conditions of cooling, heating and electricity, and the multi-energy coupling spot market, the existing solutions often lead to problems such as low utilization rate of compression heat, wasteful dissipation of expansion cooling capacity, and frequent start-up and shutdown of auxiliary equipment. As a result, the economic efficiency and energy supply quality of the energy hub cannot be guaranteed.

[0006] In summary, given the prominent multi-energy demands of industrial parks for cooling, heating, and electricity, how to leverage the unique advantages of pumped compressed air energy storage through upper and lower reservoirs with elevation differences to achieve multi-energy supply, and how to construct a systematic and optimized operation method for energy hubs, is of great value for improving the consumption of clean energy, reducing energy costs in industrial parks, and achieving multi-energy coordinated supply. This is also a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] To address the aforementioned deficiencies in the prior art, this invention provides an energy hub system based on pumped compressed air energy storage and its operation method. This solves the problem that the prior art lacks a system architecture and optimized operation method suitable for multi-energy supply energy hubs based on pumped compressed air energy storage, resulting in insufficient utilization of compression heat and expansion cold energy, and poor system operation economy and reliability.

[0008] On one hand, the present invention provides an energy hub system based on pumped compressed air energy storage, including an upper reservoir, which is an open reservoir; an air-water co-containment chamber, which is a closed structure for storing high-pressure air; a water supply pipeline, the first end of which is connected to the bottom of the upper reservoir and the second end of which is connected to the air-water co-containment chamber; an air compressor, the air inlet of which is connected to the outside atmosphere and the air outlet of which is connected to a first heat exchanger; an expander, the air inlet of which is connected to a second heat exchanger; the outlet of the heat medium flow path of the first heat exchanger is connected to the air-water co-containment chamber for sending compressed air into the air-water co-containment chamber; the air inlet of the second heat exchanger is connected to the air-water co-containment chamber for heating the high-pressure air; the inlet and outlet of the first heat exchanger are respectively connected to the outlet of the low-temperature heat storage tank and the inlet of the high-temperature heat storage tank, forming a heat recovery loop; the inlet and outlet of the second heat exchanger are respectively connected to the outlet of the high-temperature heat storage tank and the inlet of the low-temperature heat storage tank, forming a heat utilization loop.

[0009] This invention discloses an energy hub system based on pumped compressed air energy storage, using a gas-water co-containment chamber as the core energy conversion hub. This closed pressure vessel stores high-pressure air and a portion of water, with the gas and water interfaces in direct contact. The chamber is connected to the bottom of an open-type upper reservoir via a water pipeline, forming a U-shaped communicating vessel structure. During the energy storage phase, when the air compressor is driven by an external power source, ambient air is compressed into high-temperature, high-pressure gas. This gas first flows through the hot medium flow path of the first heat exchanger for cooling, and then enters the top gas phase space of the gas-water co-containment chamber. As high-pressure air is continuously injected, the air pressure inside the gas-water co-containment chamber increases, pushing the lower water body upwards through the water pipeline, ultimately entering the upper reservoir for storage. In this process, electrical energy is sequentially converted into air compression potential energy and water potential energy, while the heat of compression is recovered to the high-temperature heat storage tank through the cold medium flow path of the first heat exchanger, achieving simultaneous heat energy capture.

[0010] During the energy release phase, the water in the upper reservoir flows back to the gas-water co-containment chamber through the water pipeline under the influence of gravity, compressing the high-pressure air in the gas phase space and expelling it. This high-pressure air first enters the second heat exchanger and is heated to a high temperature before entering the expander to expand and do work, driving the generator to produce electricity. The temperature of the expanded air drops sharply, allowing it to directly provide cooling load.

[0011] Furthermore, the upper reservoir is positioned at a higher elevation, while the air-water co-containment chamber is positioned at a lower elevation, creating a hydraulic height difference between them; the water conveyance pipeline serves as the hydraulic channel between the air-water co-containment chamber and the upper reservoir. During the energy storage phase, an air compressor injects high-pressure air into the air-water co-containment chamber, increasing the pressure inside and forcing the water to rise through the water conveyance pipeline to the upper reservoir. At this point, the externally input electrical energy is converted not only into the internal energy of the compressed air but also into the gravitational potential energy of the water in the upper reservoir. The greater this height difference, the greater the potential energy that can be stored per unit volume of water, and the higher the energy storage density of the system.

[0012] During the energy release phase, the water in the upper reservoir flows back to the gas-water co-containment chamber through the water pipeline under the influence of gravity, compressing the gas phase space and expelling high-pressure air. At this time, the gravitational potential energy of the water is released, driving the air to expand and do work. The elevation difference determines the drainage pressure that can be continuously provided during the energy release process, thus affecting the stability of the expander inlet pressure.

[0013] Furthermore, the air compressor is driven by an external power source, which can be the upstream power grid, wind power, or photovoltaic power generation. The expander is connected to a generator, which outputs electrical energy to the electrical load. The air compressor can be driven by any one or more combinations of the upstream power grid, wind power, or photovoltaic power generation, reflecting the system's core function as an energy hub—absorbing fluctuating renewable energy. When the output of wind power or photovoltaic power exceeds the real-time load of the park, the surplus electricity drives the compressor to operate, converting the green electricity that might otherwise be wasted into air potential energy and water potential energy that can be stored over time.

[0014] The output shaft of the expander is connected to a generator. During the expansion of high-pressure air, the generator converts mechanical energy into electrical energy, which can be directly supplied to the electrical load in the park.

[0015] The expander and generator together constitute a typical expander-generator set, whose output power can be adjusted according to the park's electrical load demand. The generator outputs AC power at industrial frequency, which is in phase and frequency with the park's internal power grid, enabling direct grid connection for power supply.

[0016] The multi-source characteristics of external power sources and the multi-purpose output of expansion power generation together form the basis of the system's flexible interaction between "source-storage-load": during periods of high renewable energy generation, the system acts as a "load" to absorb surplus power; during peak load periods or periods of insufficient renewable energy output, the system acts as a "power source" to supply power to the park.

[0017] Furthermore, the heat output end of the high-temperature heat storage tank is connected to the heat load; the expander outlet is connected to the cold load. The core function of the high-temperature heat storage tank is "time buffering"—there is often a phase difference between the generation time of compression heat and the demand time of the park's heat load. Through the buffering storage of the heat storage tank, the decoupling and matching of the energy supply side and the energy consumption side in the time dimension can be achieved.

[0018] On the other hand, the present invention also provides an operation method for an energy hub system based on pumped compressed air energy storage, comprising: Step S1: Propose an energy hub system architecture based on pumped compressed air energy storage and sort out its full-condition operation modes, which include energy storage stage and energy release stage; Step S2: Construct a pumped compressed air energy storage operation model that takes into account both source and load uncertainties. The operation model is a two-stage robust optimization model with the goal of minimizing the overall energy supply cost or maximizing efficiency throughout the entire cycle. Step S3: Solve the two-stage robust optimization model using the Benders decomposition method to obtain the optimized operation strategy of the energy hub.

[0019] Furthermore, in step S2, the method for constructing the pumped compressed air energy storage operation model includes: Step S21: Establish a day-ahead optimal scheduling model that maximizes the comprehensive benefits of the energy hub. The objective function of the model is:

[0020] in, They are respectively Electricity prices for peak shaving, frequency regulation, and phase regulation services; These represent the power output of the expander generator that is allocated to various services at that moment; Prices for hot and cold drinks; The power to be purchased from the grid, at a price of ; The constraints of the model include electrical, thermal, and cooling load balance constraints, energy storage state transition constraints, equipment power upper and lower limit constraints, and operating condition mutual exclusion constraints. The electrical load balance constraint is:

[0021] The heat load balance constraint is:

[0022] The cooling load balance constraint is:

[0023] in, These are electrical, heating, and cooling loads, respectively. To improve the combined efficiency of expansion-based power generation and compression-based energy storage; To reduce heat recovery efficiency, To improve the efficiency of expansion cooling; The charging and releasing power of the high-temperature thermal storage tank; e, H, and C represent electricity, heat, and cold respectively; load represents the load; out and in represent the energy release power generation process and the compression energy storage process respectively; HR represents heat recovery; ch and dis represent energy charging and energy releasing respectively; HS represents the high-temperature thermal storage tank; , , These represent the electrical, heating, and cooling loads at time t, respectively. The energy storage state transition constraint is:

[0024] in, , These represent the energy states of the high-temperature heat storage tank and the compressed air energy storage at time t, respectively. , These represent the heat charging and heat release power of the high-temperature heat storage tank at time t, respectively. , These represent the pumping compressed air energy storage compression input power and expansion output power at time t, respectively. , , , These represent the efficiencies of the heat storage charging / discharging, compression, and expansion processes, respectively; Δt is the scheduling time interval. The upper and lower limits of the device power are constrained as follows:

[0025] in, , These are the lower and upper limits of thermal energy storage, respectively. , These represent the lower and upper limits of air energy storage, respectively; the subscripts l and u represent the lower and upper limits, respectively, and t is the scheduling period index; The mutually exclusive constraints of the operating conditions are as follows:

[0026] in, These are Boolean variables representing charging (compression) and discharging (expansion) conditions, respectively, with 1 indicating operation. and These represent the input power of the compressed energy storage and the output power of the expanded power generation at time t, respectively. and These represent the corresponding power limits; This indicates that the device is in compressed energy storage mode. This indicates that the system is in an expansion and energy release condition. Step S22: Construct a composite uncertain set based on the 1-norm and the -norm This is used to describe the probability distribution uncertainty of new energy output and cooling, heating, and electrical loads, in order to constrain the probability of each scenario. Deviation from initial prediction Range: Composite Uncertain Set Represented as: in, Given a deviation limit to cover prediction bias and worst-case scenarios; U is the scenario probability uncertainty set; p is the scenario probability vector. Let be the probability of the u-th scenario. Let be the initial predicted probability for the u-th scene; n is the total number of scenes, and u is the scene index; and They are respectively 1-norm, - Norm deviation limit; Step S23: Establish a two-stage robust optimization model; In the first phase, with the goal of minimizing the total system start-up and shutdown cost, the start-up and shutdown schedule for conventional units and the charging and discharging commands for the energy hub are determined, while simultaneously meeting the system inertia requirements:

[0027] in, The units The running, startup, and shutdown status; For conventional unit inertia, For virtual inertia of new energy units, The inertia provided for the expansion and power generation of the energy hub system; For the number of conventional generating units, Number of scheduling periods; , , These are the no-load cost, start-up cost, and shutdown cost of unit g, respectively. Let g be the active power output of unit g at time t. , These are the lower and upper limits of the unit's g-output, respectively; , These are the minimum start-up time and minimum downtime of unit g, respectively; Let be the total inertia of the system at time t. The minimum inertia requirement of the system; g is the index of conventional generating units, and i and j are the indices of conventional generating units and new energy generating units, respectively. The number of new energy generating units; The second stage involves the decision variables from the first stage. Once determined, for the uncertain set For the most severe scenarios involving renewable energy output and cooling, heating, and power loads, scheduling will be carried out with the goal of maximizing the total revenue of the hub (i.e., minimizing operating costs):

[0028] in, The start-up and shutdown costs for the first phase. This represents a negative value for the operating revenue of the second-phase energy hub system.

[0029] Furthermore, the step S3, which involves solving the two-stage robust optimization model using the Benders decomposition method, includes: Step S31: Initialization, settings The initial value is set, the number of iterations is set to k=1, and the upper bound is set. LB=0 The lower realm UB= 1. Set convergence error ε ; Step S32: Solve the mixed integer linear programming problem in the first stage to obtain the optimal solution and update the lower bound; Step S33: Substitute the optimal solution from the first stage into the optimization problem of the second stage and solve it to obtain the optimal solution and update the upper bound; Step S34: Determine | UB-LB| Is it less than the convergence error? ε If yes, the algorithm converges and outputs the optimized running strategy; otherwise, generate a Benders feasible cut or optimal cut based on the dual information of the subproblem, add it to the constraints of the main problem, let k=k+1, and return to step S32 to continue iterating.

[0030] Furthermore, the optimized operation strategy includes: during the energy storage phase, controlling the operation of the air compressor to generate high-pressure air that is injected into the gas-water co-containment chamber, driving the water to flow into the upper reservoir, while recovering the heat of compression to supply the heat load; during the energy release phase, the water in the upper reservoir flows back to the gas-water co-containment chamber, driving the high-pressure air to be released from the gas-water co-containment chamber into the expander to do work and generate electricity, while the expansion cooling capacity supplies the cooling load.

[0031] Furthermore, the full-condition operation mode outlined in step S1 includes: In the energy storage stage, surplus electricity is used to drive an air compressor to draw in and compress air. The resulting high-pressure air is cooled by the first heat exchanger and then sent into the air-water co-containment chamber. The increased air pressure pushes the water in the air-water co-containment chamber to flow into the upper reservoir through the water pipeline. Electrical energy is converted into air potential energy and water gravity potential energy. At the same time, the first heat exchanger recovers the compression heat and stores it in a high-temperature heat storage tank. In the energy release stage, the water in the upper reservoir flows back to the air-water co-containment chamber through the water pipeline under the action of gravity. The high-pressure air is compressed and enters the expander to expand and do work, driving the generator to generate electricity. The expanded low-temperature air directly provides the cooling load.

[0032] Compared with the prior art, the present invention has the following beneficial effects: I. This invention provides an energy hub system based on pumped water compressed air energy storage, which complements the advantages of pumped water storage and compressed air energy storage. Through the physical coupling of the air-water co-containment chamber and the elevation difference reservoir, the system utilizes the coordinated energy conversion driven by air pressure and water gravity. It realizes the coordinated production, storage and supply of three energy forms—electricity, heat and cold—within a single process, reducing the need for additional configuration of heat pumps, boilers or refrigeration units for multi-energy supply, simplifying the system structure and reducing initial investment.

[0033] Second, in the operation method of the energy hub system based on pumped compressed air energy storage of the present invention, the efficient recovery and utilization of compressed heat is incorporated into the core decision variables by constructing an optimized operation model, and matched and optimized with the dynamic heating and cooling load of the industrial park. This solves the problem of extensive or abandoned heat and cooling utilization in traditional energy storage systems, and significantly improves the overall energy utilization efficiency and economic benefits of the system.

[0034] Third, the two-stage robust optimization model and Benders decomposition solution method proposed in the operation method of an energy hub system based on pumped compressed air energy storage in this invention can systematically address challenges such as fluctuations in renewable energy output, variable loads, and market price uncertainties in industrial parks. The generated optimized operation strategy is immune to uncertainty and can ensure a reliable supply of cooling, heating, and electricity under the most unfavorable source and load conditions, thereby improving the robustness and safety of the energy hub operation. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of an energy hub system based on pumped compressed air energy storage proposed in this invention.

[0036] The components include: 1. Upper reservoir; 2. Gas-water co-containment chamber; 3. Water pipeline; 4. Air compressor; 5. First heat exchanger; 6. Expander; 7. Second heat exchanger; 8. High-temperature heat storage tank; 9. Low-temperature heat storage tank. Detailed Implementation

[0037] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0038] like Figure 1 As shown, this embodiment provides an energy hub system based on pumped compressed air energy storage, including an upper reservoir 1, an air-water co-containment chamber 2, a water pipeline 3, an air compressor 4, a first heat exchanger 5, an expander 6, a second heat exchanger 7, a high-temperature heat storage tank 8, and a low-temperature heat storage tank 9.

[0039] Upper Reservoir 1 is an open-type reservoir, typically built at a higher elevation to store water and utilize gravitational potential energy. The air-water co-containment chamber 2 is located at a lower elevation, forming a closed cavity capable of simultaneously storing high-pressure air and water; it is the core component for coupling hydraulic potential energy with compressed air potential energy. The first end of the water conveyance pipe 3 extends into and connects to the bottom water area of ​​Upper Reservoir 1, and the second end extends into and connects to the air-water co-containment chamber 2, thus creating a channel for water flow between the two. A hydraulic height difference exists between the air-water co-containment chamber 2 and Upper Reservoir 1 due to their different elevations.

[0040] The air compressor 4 has its inlet connected to the outside atmosphere via a pipe, for drawing in ambient air. The air compressor 4's outlet is connected via a pipe to the inlet of the heat medium flow path of the first heat exchanger 5. The outlet of the heat medium flow path of the first heat exchanger 5 is connected via a pipe to the air-water co-containment chamber 2. Thus, during the energy storage phase, after the air compressor 4 draws in air and compresses and heats it, the high-temperature, high-pressure air enters the first heat exchanger 5 for heat exchange.

[0041] The inlet pipe of the second heat exchanger 7 is connected to the gas-water co-containment chamber 2, used to introduce and heat the high-pressure air stored therein. The inlet pipe of the expander 6 is connected to the outlet pipe of the second heat exchanger 7, used to introduce high-temperature, high-pressure air. The exhaust port of the expander 6 is connected to the cold load side via a pipe. During the energy release phase, the high-pressure air enters the expander 6, expands, and performs work, driving the generator to generate electricity, while the air temperature decreases significantly.

[0042] The high-temperature heat storage tank 8 is used to store thermal energy. The inlet and outlet of the high-temperature heat storage tank 8 are connected to the cold medium flow path outlet and inlet of the first heat exchanger 5 via pipes, thus forming a closed heat recovery loop. In this loop, low-temperature heat transfer oil circulates under the drive of a pump. During energy storage, high-temperature compressed air flows through the hot medium side of the first heat exchanger 5, transferring heat to the low-temperature heat transfer oil on the cold medium side. The heated low-temperature heat transfer oil flows into the high-temperature heat storage tank 8 to store heat, or supplies hot water or steam to the heat load through the heat exchanger.

[0043] The system works as follows: Energy storage stage: The air compressor 4 is driven by surplus electricity from the industrial park (such as photovoltaic and wind power) or off-peak electricity from the power grid. After compression, the air's temperature and pressure increase, and it is cooled by the first heat exchanger 5 before entering the air-water co-containment chamber 2. With the injection of high-pressure air, the pressure inside the air-water co-containment chamber 2 increases, propelling the water inside through the water pipe 3 to the upper reservoir 1. Electrical energy is converted into the potential energy of the compressed air and the gravitational potential energy of the water in the upper reservoir 1. Simultaneously, the heat generated during compression is recovered in the first heat exchanger 5 and stored in the high-temperature heat storage tank 8 or used for heating, achieving combined heat and power generation.

[0044] Energy Release Stage: When the industrial park requires electricity, the valve is opened, and the water in the upper reservoir 1 flows naturally back to the air-water co-containment chamber 2 under gravity through the water pipeline 3. The returning water compresses the high-pressure air in the air-water co-containment chamber 2, causing it to expand and do work through the pipe into the expander 6, driving the generator to generate electricity. The expanded air temperature is significantly reduced, allowing it to be directly used for cooling, thus achieving combined cooling and power generation. The entire process requires no additional water pumps or turbines to drive the water circulation; it relies on air pressure difference and gravity for propulsion, resulting in a simple and efficient structure.

[0045] This embodiment also provides an operation method for an energy hub system based on pumped compressed air energy storage, including the following steps: Step S1: Propose an energy hub system architecture based on pumped compressed air energy storage and outline its full-condition operation modes. This step involves constructing the system described in the above embodiments and clarifying its two basic operating conditions: energy storage and energy release, as well as the accompanying heat production and recovery modes.

[0046] Step S2: Construct a pumped compressed air energy storage operation model that takes into account both source and load uncertainties. The operation model is a two-stage robust optimization model with the goal of minimizing the overall energy supply cost or maximizing efficiency throughout the entire cycle.

[0047] Specifically, the methods for constructing a pumped compressed air energy storage operation model include: Step S21: Establish a day-ahead optimal scheduling model that maximizes the comprehensive benefits of the energy hub. This model is a basic deterministic model used to describe the economic operation logic of the system under a given forecast scenario. The objective function of the model is:

[0048] in, They are respectively Electricity prices for peak shaving, frequency regulation, and phase regulation services; These represent the power output of the expander generator that is allocated to various services at that moment; Prices for hot and cold drinks; The power to be purchased from the grid, at a price of ; The constraints of the model include electrical, thermal, and cooling load balance constraints, energy storage state transition constraints, equipment power upper and lower limit constraints, and operating condition mutual exclusion constraints. The electrical load balance constraint is:

[0049] The heat load balance constraint is:

[0050] The cooling load balance constraint is:

[0051] in, These are electrical, heating, and cooling loads, respectively. To improve the combined efficiency of expansion-based power generation and compression-based energy storage; To reduce heat recovery efficiency, To improve the efficiency of expansion cooling; The charging and releasing power of the high-temperature thermal storage tank; e, H, and C represent electricity, heat, and cold respectively; load represents the load; out and in represent the energy release power generation process and the compression energy storage process respectively; HR represents heat recovery; ch and dis represent energy charging and energy releasing respectively; HS represents the high-temperature thermal storage tank; , , These represent the electrical, heating, and cooling loads at time t, respectively. The energy storage state transition constraint is:

[0052] in, , These represent the energy states of the high-temperature heat storage tank and the compressed air energy storage at time t, respectively. , These represent the heat charging and heat release power of the high-temperature heat storage tank at time t, respectively. , These represent the pumping compressed air energy storage compression input power and expansion output power at time t, respectively. , , , , , These represent the efficiencies of the heat storage charging / discharging, cold storage charging / discharging, compression, and expansion processes, respectively; Δt is the scheduling time interval. The upper and lower limits of the device power are constrained as follows:

[0053] in, , These are the lower and upper limits of thermal energy storage, respectively. , These represent the lower and upper limits of air energy storage, respectively; the subscripts l and u represent the lower and upper limits, respectively, and t is the scheduling period index; The mutually exclusive constraints of the operating conditions are as follows:

[0054] in, These are Boolean variables representing charging (compression) and discharging (expansion) conditions, respectively, with 1 indicating operation. and These represent the input power of the compressed energy storage and the output power of the expanded power generation at time t, respectively. and These represent the corresponding power limits; This indicates that the device is in compressed energy storage mode. This indicates that the system is in an expansion and energy release condition. Step S22: Construct a composite uncertain set based on the 1-norm and the -norm This is used to describe the probability distribution uncertainty of new energy output and cooling, heating, and electrical loads, in order to constrain the probability of each scenario. Deviation from initial prediction Amplitude: Composite Uncertain Set Represented as: in, Given a deviation limit to cover prediction bias and worst-case scenarios; U is the scenario probability uncertainty set; p is the scenario probability vector. Let be the probability of the u-th scenario. Let be the initial predicted probability for the u-th scene; n is the total number of scenes, and u is the scene index; and They are respectively 1-norm, - Norm deviation limit; Step S23: Establish a two-stage robust optimization model; The first phase (the main problem) aims to minimize the total system start-up and shutdown cost, determining the start-up and shutdown schedule for conventional units and the charging and discharging commands for the energy hub, while simultaneously meeting system inertia requirements:

[0055] in, The units The running, startup, and shutdown status; For conventional unit inertia, For virtual inertia of new energy units, The inertia provided for the expansion and power generation of the energy hub system; For the number of conventional generating units, Number of scheduling periods; , , These are the no-load cost, start-up cost, and shutdown cost of unit g, respectively. Let g be the active power output of unit g at time t. , These are the lower and upper limits of the unit's g-output, respectively; , These are the minimum start-up time and minimum downtime of unit g, respectively; Let be the total inertia of the system at time t. The minimum inertia requirement of the system; g is the index of conventional generating units, and i and j are the indices of conventional generating units and new energy generating units, respectively. The number of new energy generating units; The second stage (sub-problem) involves the decision variables from the first stage. Once determined, for the uncertain set For the most severe scenarios involving renewable energy output and cooling, heating, and power loads, scheduling will be carried out with the goal of maximizing the total revenue of the hub (i.e., minimizing operating costs):

[0056] in, The start-up and shutdown costs for the first phase. This represents a negative value for the operating revenue of the second-phase energy hub system.

[0057] Step S3: Solve the two-stage robust optimization model using the Benders decomposition method to obtain the optimized operation strategy of the energy hub. The optimized operation strategy includes: in the energy storage stage, controlling the operation of the air compressor, injecting the generated high-pressure air into the gas-water co-containment chamber, driving the water to flow into the upper reservoir, and simultaneously recovering the heat of compression to supply the heat load; in the energy release stage, the water in the upper reservoir flows back to the gas-water co-containment chamber, driving the high-pressure air to be released from the gas-water co-containment chamber into the expander to do work and generate electricity, while the expanded low-temperature exhaust gas supplies the cooling load.

[0058] Specifically, including: Step S31: Initialization, settings The initial value is set, the number of iterations is set to k=1, and the upper bound is set. LB=0 The lower realm UB= 1. Set convergence error ε ; Step S32: When iterating k, solve the first stage mixed integer linear programming problem to obtain the optimal solution and update the lower bound; Step S33: Substitute the optimal solution from the first stage into the optimization problem of the second stage and solve it to obtain the optimal solution and update the upper bound; Step S34: Determine | UB-LB| Is it less than the convergence error? ε If the conditions are met, the algorithm converges and outputs an optimized operating strategy; otherwise, it generates a Benders feasible cut or optimal cut based on the dual information of the subproblem, adds it to the constraints of the main problem, sets k=k+1, and returns to step S32 to continue iteration. Through this decomposition and iteration, the algorithm can effectively handle integer variables and uncertainties in the two-stage model, ultimately obtaining an economical and robust optimized operating strategy under source load uncertainty, guiding the energy hub to perform optimized scheduling both day-ahead and in real-time.

Claims

1. An energy hub system based on pumped compressed air energy storage, characterized in that, include: Upper Reservoir (1) is an open-type reservoir; The air-water co-containment chamber (2) is a closed structure used to store high-pressure air; The water pipeline (3) has its first end connected to the bottom of the upper reservoir (1) and its second end connected to the air-water co-containment chamber (2). An air compressor (4) has an air inlet for connecting to the outside atmosphere and an air outlet connected to a first heat exchanger (5). The expander (6) has its exhaust port directly connected to the cold load; The outlet of the heat medium flow path of the first heat exchanger (5) is connected to the gas-water co-containment chamber (2) to send compressed air into the gas-water co-containment chamber (2). The air inlet of the expander (6) is connected to the air-water co-containment chamber (2) for introducing high-pressure air; The high-temperature heat storage tank (8), the low-temperature heat storage tank (9), the first heat exchanger (5), and the second heat exchanger (7) form a closed heat transfer oil circulation loop. The output pipeline branch of the high-temperature heat storage tank (8) is connected to the heat load.

2. The energy hub system based on pumped compressed air energy storage according to claim 1, characterized in that, The upper reservoir (1) is located at a high position, and the air-water co-containment chamber (2) is located at a low position, forming a hydraulic height difference between the two; the water conveyance pipeline (3) is the hydraulic channel between the air-water co-containment chamber (2) and the upper reservoir (1).

3. The energy hub system based on pumped compressed air energy storage according to claim 1, characterized in that, The air compressor (4) is driven by an external power source, which is the upstream power grid, wind power, or photovoltaic power generation; the expander (6) is connected to a generator, which outputs electrical energy to the electrical load.

4. The energy hub system based on pumped compressed air energy storage according to claim 1, characterized in that, The heat output end of the high-temperature heat storage tank (8) is connected to the heat load; the exhaust gas outlet of the expander is connected to the cold load.

5. An operation method for an energy hub system based on pumped compressed air energy storage as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step S1: Propose an energy hub system architecture based on pumped compressed air energy storage and sort out its full-condition operation modes, which include energy storage stage and energy release stage; Step S2: Construct a pumped compressed air energy storage operation model that takes into account both source and load uncertainties. The operation model is a two-stage robust optimization model with the goal of minimizing the overall energy supply cost or maximizing efficiency throughout the entire cycle. Step S3: Solve the two-stage robust optimization model using the Benders decomposition method to obtain the optimized operation strategy of the energy hub.

6. The operation method of the energy hub system based on pumped compressed air energy storage according to claim 5, characterized in that, In step S2, the method for constructing the pumped compressed air energy storage operation model includes: Step S21: Establish a day-ahead optimal scheduling model that maximizes the comprehensive benefits of the energy hub. The objective function of the model is: in, They are respectively Electricity prices for peak shaving, frequency regulation, and phase regulation services; These represent the power output of the expander generator that is allocated to various services at that moment; Prices for hot and cold drinks; The power to be purchased from the grid, at a price of ; The constraints of the model include electrical, thermal, and cooling load balance constraints, energy storage state transition constraints, equipment power upper and lower limit constraints, and operating condition mutual exclusion constraints. The electrical load balance constraint is: The heat load balance constraint is: The cooling load balance constraint is: in, These are electrical, heating, and cooling loads, respectively. To improve the combined efficiency of expansion-based power generation and compression-based energy storage; To reduce heat recovery efficiency, To improve the efficiency of expansion cooling; The charging and releasing power of the high-temperature thermal storage tank; e, H, and C represent electricity, heat, and cold respectively; load represents the load; out and in represent the energy release power generation process and the compression energy storage process respectively; HR represents heat recovery; ch and dis represent energy charging and energy releasing respectively; HS represents the high-temperature thermal storage tank; , , These represent the electrical, heating, and cooling loads at time t, respectively. The energy storage state transition constraint is: in, , These represent the energy states of the high-temperature thermal storage tank and the compressed air energy storage at time t, respectively. , These represent the heat charging and heat release power of the high-temperature heat storage tank at time t, respectively. , These represent the pumping compressed air energy storage compression input power and expansion output power at time t, respectively. , , , , , These represent the efficiencies of the heat storage charging / discharging, cold storage charging / discharging, compression, and expansion processes, respectively; Δt is the scheduling time interval. The upper and lower limits of the device power are constrained as follows: in, , These are the lower and upper limits of thermal energy storage, respectively. , These represent the lower and upper limits of air energy storage, respectively; the subscripts l and u represent the lower and upper limits, respectively, and t is the scheduling period index; The mutually exclusive constraints of the operating conditions are as follows: in, These are Boolean variables representing charging (compression) and discharging (expansion) conditions, respectively, with 1 indicating operation. and These represent the input power of the compressed energy storage and the output power of the expanded power generation at time t, respectively. and These are the corresponding power limits; This indicates that the device is in compressed energy storage mode. This indicates that the system is in an expansion and energy release condition. Step S22: Construct a composite uncertain set based on the 1-norm and the -norm This is used to describe the probability distribution uncertainty of new energy output and cooling, heating, and electrical loads, in order to constrain the probability of each scenario. Deviation from initial prediction Range: Composite Uncertain Set Represented as: in, Given a deviation limit to cover prediction bias and worst-case scenarios; U is the scenario probability uncertainty set; p is the scenario probability vector. Let be the probability of the u-th scenario. Let be the initial predicted probability for the u-th scene; n is the total number of scenes, and u is the scene index; and They are respectively 1-norm, - Norm deviation limit; Step S23: Establish a two-stage robust optimization model; In the first phase, with the goal of minimizing the total system start-up and shutdown cost, the start-up and shutdown schedule for conventional units and the charging and discharging commands for the energy hub are determined, while simultaneously meeting the system inertia requirements: in, The units The running, startup, and shutdown status; For conventional unit inertia, For virtual inertia of new energy units, The inertia provided for the expansion and power generation of the energy hub system; For the number of conventional generating units, Number of scheduling periods; , , These are the no-load cost, start-up cost, and shutdown cost of unit g, respectively; Let g be the active power output of unit g at time t. , These are the lower and upper limits of the unit's g-output, respectively; , These are the minimum start-up time and minimum downtime of unit g, respectively; Let be the total inertia of the system at time t. The minimum inertia requirement of the system; g is the index of conventional generating units, and i and j are the indices of conventional generating units and new energy generating units, respectively. The number of new energy generating units; The second stage involves the decision variables from the first stage. Once determined, for the uncertain set The most severe scenarios involving renewable energy output and cooling, heating, and power loads will be addressed through scheduling aimed at maximizing the total revenue of the hub. in, The start-up and shutdown costs for the first phase. This represents a negative value for the operating revenue of the second-phase energy hub system.

7. The operation method of the energy hub system based on pumped compressed air energy storage according to claim 6, characterized in that, The steps in step S3, which involve solving the two-stage robust optimization model using the Benders decomposition method, include: Step S31: Initialization, settings The initial value is set, the number of iterations is set to k=1, and the upper bound is set. LB=0 The lower realm UB= 1. Set convergence error ε ; Step S32: Solve the mixed integer linear programming problem in the first stage to obtain the optimal solution and update the lower bound; Step S33: Substitute the optimal solution from the first stage into the optimization problem of the second stage and solve it to obtain the optimal solution and update the upper bound; Step S34: Determine | UB-LB| Is it less than the convergence error? ε If yes, the algorithm converges and outputs the optimized running strategy; otherwise, generate a Benders feasible cut or optimal cut based on the dual information of the subproblem, add it to the constraints of the main problem, let k=k+1, and return to step S32 to continue iterating.

8. The operation method of the energy hub system based on pumped compressed air energy storage according to claim 5, characterized in that, The optimized operation strategy includes: during the energy storage stage, the air compressor (4) is controlled to operate, and the high-pressure air generated is injected into the gas-water co-containment chamber (2) to drive the water to flow into the upper reservoir (1), while recovering the heat of compression to supply the heat load; during the energy release stage, the water in the upper reservoir (1) flows back to the gas-water co-containment chamber (2), and drives the high-pressure air to be released from the gas-water co-containment chamber (2) into the expander (6) to do work and generate electricity, while the low-temperature exhaust gas after expansion directly supplies the cold load.

9. The operation method of the energy hub system based on pumped compressed air energy storage according to claim 5, characterized in that, The full-condition operation modes identified in step S1 include: During the energy storage phase, the surplus electricity is used to drive the air compressor (4) to draw in and compress air. The high-pressure air generated is cooled by the first heat exchanger (5) and sent into the air-water co-containment chamber (2). The increased air pressure pushes the water in the air-water co-containment chamber (2) to flow into the upper reservoir (1) through the water pipeline (3). The electrical energy is converted into air potential energy and water gravity potential energy. At the same time, the first heat exchanger (5) recovers the compression heat and stores it in the high-temperature heat storage tank (8). During the energy release phase, the water in the upper reservoir (1) flows back to the air-water co-containment chamber (2) through the water pipeline (3) under the action of gravity. The high-pressure air is squeezed into the second heat exchanger (7) to absorb the heat from the high-temperature heat storage tank (8), and then enters the expander (6) to expand and do work, driving the generator to generate electricity. The expanded low-temperature air directly provides cooling for users.

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