CN111271143A - System and method for improving electric power flexibility - Google Patents

Abstract

The invention discloses a system and a method for improving electric flexibility, wherein the system consists of a multistage compressor, a multistage cooler, a gas-liquid conversion device, a liquid air storage tank, a multistage heater, a multistage expander, a heat storage system, a generator set, a flexibility control device and a control valve; the operation method of the system comprises an energy storage mode and an energy release mode; when the method is applied to a coal-fired power plant, the peak regulation capacity and the response speed of the unit can be improved, the frequency modulation performance of the unit can be improved, the stability of the electric output power can be improved when the method is applied to a photovoltaic power plant and a wind power plant, and the consumption capacity of a power grid to new energy can be improved.

Description

Translated fromChinese

一种提高电力灵活性的系统及方法A system and method for improving power flexibility

技术领域technical field

本发明属于储能调峰技术领域，具体涉及一种提高电力灵活性的系统及方法，适用于燃煤机组等具有灵活性需求的电厂，也适用于光伏、风电等需要稳定输出的电厂，能够改善电厂的电能品质，提高电力系统的稳定性。The invention belongs to the technical field of energy storage and peak regulation, and in particular relates to a system and method for improving power flexibility, which is suitable for power plants with flexibility requirements such as coal-fired units, as well as power plants requiring stable output such as photovoltaics and wind power. Improve the power quality of the power plant and improve the stability of the power system.

背景技术Background technique

目前我国风能、太阳能等可再生能源逐年迅猛发展，加之全社会用电量逐年攀升，电网用电峰谷差日益增大，电网对燃煤机组调峰次数及深度的要求均大幅提升。At present, my country's wind energy, solar energy and other renewable energy sources are developing rapidly year by year. In addition, the electricity consumption of the whole society is increasing year by year, and the peak-to-valley difference of power grid power consumption is increasing.

目前提高燃煤机组调峰能力的技术主要有电锅炉蓄热技术、水罐蓄热技术、汽轮机蒸汽流程改造技术、电化学电池储能技术等，电锅炉蓄热技术是将电能转化为热能后用于供暖，调峰能力强，但能量品质大幅度降低、只适用于热电联产机组，水罐蓄热技术和汽轮机蒸汽流程改造技术热经济性较好、投资相对低，但调峰能力有限，也只适用于热电联产机组，电化学电池储能技术响应快、体积小、建设周期短，但寿命短、平均成本很高、安全风险大，是否适合建设大规模储能实施仍需工程示范验证。At present, the technologies for improving the peak regulation capacity of coal-fired units mainly include electric boiler heat storage technology, water tank heat storage technology, steam turbine steam process transformation technology, electrochemical battery energy storage technology, etc. It is used for heating, with strong peak shaving ability, but the energy quality is greatly reduced, and it is only suitable for cogeneration units. The water tank heat storage technology and the steam turbine steam process transformation technology have good thermal economy and relatively low investment, but the peak shaving capacity is limited. , and only applies to cogeneration units. Electrochemical battery energy storage technology has fast response, small size, and short construction period, but has short lifespan, high average cost, and high safety risks. Whether it is suitable for large-scale energy storage implementation still needs engineering Demonstration verification.

针对上述问题，提出了一种提高电力灵活性的系统及方法，适用于热电联产机组和纯凝机组，也适用于光伏电厂和风电厂，该方法可以显著提高电厂的发电灵活性和电网的稳定性，增强电网对新能源发电的消纳能力。In view of the above problems, a system and method for improving power flexibility are proposed, which are suitable for cogeneration units and pure condensing units, as well as photovoltaic power plants and wind power plants. This method can significantly improve the power generation flexibility of power plants and the stability of power grids enhance the power grid's ability to absorb new energy power generation.

发明内容SUMMARY OF THE INVENTION

为提高电厂发电的灵活性和稳定性，本发明提出一种提高电力灵活性的系统及方法，适用于燃煤机组等具有灵活性需求的电厂，也适用于光伏、风电等需要稳定输出的电厂，能够改善电厂的电能品质，提高电力系统的稳定性。In order to improve the flexibility and stability of power generation of power plants, the present invention proposes a system and method for improving power flexibility, which is suitable for power plants with flexibility requirements such as coal-fired units, and also for power plants requiring stable output such as photovoltaics and wind power. , which can improve the power quality of the power plant and improve the stability of the power system.

为了达到上述目的，本发明采用如下技术方案。In order to achieve the above objects, the present invention adopts the following technical solutions.

一种提高电力灵活性的系统，由多级压缩机、多级冷却器、气液转换装置5、液体空气储罐6、多级加热器、多级膨胀机、储热系统冷罐11、储热系统热罐12、第一阀门13、第二阀门14、发电机组15和灵活性控制装置16所组成；A system for improving power flexibility, consisting of a multi-stage compressor, a multi-stage cooler, a gas-liquid conversion device 5, a liquid-air storage tank 6, a multi-stage heater, a multi-stage expander, a heat storage system cold tank 11, a storage The heat system heat tank 12, thefirst valve 13, thesecond valve 14, the generator set 15 and theflexibility control device 16 are composed;

所述多级压缩机和多级冷却器一一对应，每级压缩机后串联对应的冷却器；所述多级加热器和多级膨胀机一一对应，每级加热器后串联对应的膨胀机；第一级压缩机出口依次连通第一级冷却器高温侧入口、第一级冷却器高温侧出口、第二级压缩机、第二级冷却器高温侧入口、二级冷却器高温侧出口、直至末级压缩机、末级冷却器高温侧入口、末级冷却器高温侧出口、气液转换装置5降温液化侧入口、气液转换装置5降温液化侧出口和液体空气储罐6入口；液体空气储罐6出口依次连通气液转换装置5冷能回收侧入口、气液转换装置5冷能回收侧出口、第一级加热器低温侧入口、第一级加热器低温侧出口、第一级膨胀机、第二级加热器低温侧入口、第二级加热器低温侧出口、第二级膨胀机、直至末级加热器低温侧入口、末级加热器低温侧出口和末级膨胀机；储热系统冷罐11出口通过第一阀门13与第一级冷却器低温侧入口、第二级冷却器低温侧入口、直至末级冷却器低温侧入口连通，第一级冷却器低温侧出口、第二级冷却器低温侧出口、直至末级冷却器低温侧出口与储热系统热罐12入口连通，储热系统热罐12出口通过第二阀门14与第一级加热器高温侧入口、第二级加热器高温侧入口、直至末级加热器高温侧入口连通，第一级加热器高温侧出口、第二级加热器高温侧出口、直至末级加热器高温侧出口与储热系统冷罐11入口连接；灵活性控制装置16接受需求信号，并与发电机组15、外部电网、多级压缩机和多级膨胀机设有电路连接；该系统适用于具有灵活性需求的电厂，也适用于需要稳定输出的电厂，能够改善电厂的电能品质，提高电力系统的稳定性。The multi-stage compressors and the multi-stage coolers are in one-to-one correspondence, and each stage of the compressor is connected in series with the corresponding cooler; the multi-stage heater and the multi-stage expander are in one-to-one correspondence, and each stage of the heater is connected in series with the corresponding expansion machine. The outlet of the first stage compressor is sequentially connected to the high temperature side inlet of the first stage cooler, the high temperature side outlet of the first stage cooler, the second stage compressor, the high temperature side inlet of the second stage cooler, and the high temperature side outlet of the second stage cooler. , until the last stage compressor, the high temperature side inlet of the last stage cooler, the high temperature side outlet of the last stage cooler, the gas-liquid conversion device 5 cooling and liquefaction side inlet, the gas-liquid conversion device 5 cooling and liquefaction side outlet and the liquid air storage tank 6 inlet; The outlet of the liquid air storage tank 6 is sequentially connected to the inlet of the gas-liquid conversion device 5 on the cold energy recovery side, the outlet of the cold energy recovery side of the gas-liquid conversion device 5, the inlet on the low temperature side of the first stage heater, the outlet on the low temperature side of the first stage heater, and the first stage heater. Stage expander, low temperature side inlet of second stage heater, low temperature side outlet of second stage heater, second stage expander, until low temperature side inlet of last stage heater, low temperature side outlet of last stage heater and last stage expander; The outlet of the cold tank 11 of the heat storage system is communicated with the low temperature side inlet of the first stage cooler, the low temperature side inlet of the second stage cooler, and the low temperature side inlet of the last stage cooler through thefirst valve 13, and the low temperature side outlet of the first stage cooler, The outlet of the low temperature side of the second stage cooler and the outlet of the low temperature side of the last stage cooler are connected with the inlet of the heat storage system heat tank 12, and the outlet of the heat storage system heat tank 12 is connected to the high temperature side inlet of the first stage heater through thesecond valve 14, The high temperature side inlet of the second stage heater is connected to the high temperature side inlet of the last stage heater, the high temperature side outlet of the first stage heater, the high temperature side outlet of the second stage heater, and the high temperature side outlet of the last stage heater are connected with the cold tank of the heat storage system 11 Inlet connection;flexibility control device 16 accepts demand signals and has circuit connections withgenerator sets 15, external power grids, multi-stage compressors and multi-stage expanders; the system is suitable for power plants with flexibility needs, and also for Power plants that require stable output can improve the power quality of the power plant and improve the stability of the power system.

所述灵活性控制装置16根据需求信号选择使用发电机组15发电量或外部电网电量驱动压缩机，或者同时使用这两部分电量驱动压缩机。Theflexibility control device 16 selects to use the power generated by thegenerator set 15 or the external grid power to drive the compressor according to the demand signal, or use the two parts of the power to drive the compressor at the same time.

所述灵活性控制装置16根据需求信号控制膨胀机的启停，并将膨胀机发电量输送至外部电网。Theflexibility control device 16 controls the start and stop of the expander according to the demand signal, and transmits the power generated by the expander to the external power grid.

优选地，所述多级压缩机为两级，分别为一级压缩机1和二级压缩机3，所述多级冷却器为两级，分别为一级冷却器2和二级冷却器4。Preferably, the multi-stage compressor has two stages, which are the primary compressor 1 and the secondary compressor 3 respectively, and the multi-stage cooler has two stages, which are the primary cooler 2 and the secondary cooler 4 respectively. .

优选地，所述多级加热器为两级，分别为一级加热器7和二级加热器9，所述多级膨胀机为两级，分别为一级膨胀机8和二级膨胀机10。Preferably, the multi-stage heater has two stages, which are the first-stage heater 7 and the second-stage heater 9 respectively, and the multi-stage expander has two stages, which are the first-stage expander 8 and the second-stage expander 10 respectively. .

所述储热系统冷罐11和储热系统热罐12将压缩空气过程中产生的热量储存起来，在释能模式下用于加热低温空气然后推动膨胀机发电。The heat storage system cold tank 11 and the heat storage system hot tank 12 store the heat generated in the process of compressing the air, and use it to heat the low-temperature air in the energy release mode and then drive the expander to generate electricity.

应用于燃煤电厂时能够提高机组的调峰能力和响应速度，并且改善机组的调频性能，应用于光伏电厂和风电厂时能够提高电输出功率的稳定性，提高电网对新能源的消纳能力。When applied to coal-fired power plants, it can improve the peak regulation capacity and response speed of the unit, and improve the frequency regulation performance of the unit. When applied to photovoltaic power plants and wind power plants, it can improve the stability of electrical output power and improve the grid's ability to absorb new energy.

所述的一种提高电力灵活性的系统的运行方法，包括储能模式和释能模式，具体如下：The operation method of a system for improving power flexibility includes an energy storage mode and an energy release mode, and the details are as follows:

储能模式：发电机组15需要降低电输出功率时，开启储能模式，打开第一阀门13，关闭第二阀门14；灵活性控制装置16根据需求信号选择使用发电机组15发电量或外部电网电量驱动多级压缩机，或者同时使用这两部分电量，常温常压空气经第一级压缩机压缩后进入第一级冷却器，再经第二级压缩机压缩后进入第二级冷却器，直至经末级压缩机压缩后进入末级冷却器成为常温高压空气，储热介质由储热系统冷罐11经第一阀门13进入第一级冷却器2、第二级冷却器4、直至末级冷却器冷却空气，得到的高温储热介质储存在储热系统热罐12中，常温高压空气经过气液转换装置5进行降温液化，低温液态空气进入液体空气储罐6储存；Energy storage mode: when thegenerator set 15 needs to reduce the electrical output power, the energy storage mode is turned on, thefirst valve 13 is opened, and thesecond valve 14 is closed; theflexibility control device 16 selects to use the power generation of thegenerator set 15 or the power of the external grid according to the demand signal Drive the multi-stage compressor, or use the two parts of electricity at the same time, the normal temperature and pressure air is compressed by the first-stage compressor and then enters the first-stage cooler, and then compressed by the second-stage compressor and then enters the second-stage cooler until After being compressed by the final stage compressor, it enters the final stage cooler to become normal temperature and high pressure air. The heat storage medium enters the first stage cooler 2, the second stage cooler 4 and the final stage from the cold tank 11 of the heat storage system through thefirst valve 13. The cooler cools the air, the obtained high temperature heat storage medium is stored in the heat storage system heat tank 12, the normal temperature high pressure air is cooled and liquefied through the gas-liquid conversion device 5, and the low temperature liquid air enters the liquid air storage tank 6 for storage;

释能模式：发电机组15需要提高电输出功率时开启释能模式，关闭第一阀门13，打开第二阀门14；低温液态空气从液体空气储罐6流出，经气液转换装置5进行冷能回收后生成的常温高压空气进入第一级加热器加热，加热后的空气进入第一级膨胀机发电，再进入第二级加热器加热，加热后的空气进入第二级膨胀机发电，直至进入末级加热器加热，加热后的空气进入末级膨胀机发电，末级膨胀机出口为常压常温空气，排入周围环境，电量通过灵活性控制装置16输送至外部电网，高温储热介质由储热系统热罐12经第二阀门14进入第一级加热器7、第二级加热器9、直至末级加热器加热空气，得到的低温储热介质随后储存在储热系统冷罐11中。Energy release mode: when the generator set 15 needs to increase the electrical output power, the energy release mode is turned on, thefirst valve 13 is closed, and thesecond valve 14 is opened; The normal temperature and high pressure air generated after recovery enters the first-stage heater for heating, the heated air enters the first-stage expander for power generation, and then enters the second-stage heater for heating, and the heated air enters the second-stage expander for power generation until it enters the The final stage heater is heated, and the heated air enters the final stage expander to generate electricity. The outlet of the final stage expander is normal pressure and normal temperature air, which is discharged into the surrounding environment. The electricity is sent to the external power grid through theflexibility control device 16. The heat storage system hot tank 12 enters the first stage heater 7, thesecond stage heater 9, and the final stage heater through thesecond valve 14 to heat the air, and the obtained low-temperature heat storage medium is then stored in the heat storage system cold tank 11. .

和现有技术相比较，本发明具备如下优点：Compared with the prior art, the present invention has the following advantages:

本发明通过灵活性控制装置将空气压缩机、空气膨胀机与发电设备耦合起来，通过“电能—压缩机—空气分子势能—膨胀机—电能”的工作过程完成电能的储存，储电效率较高，避免了电锅炉由电转化为热所造成的能级损耗，与水罐蓄热技术和汽轮机蒸汽流程改造技术相比，扩大了调节能力和应用场景，与电化学电池储能技术相比，提高了使用寿命、降低了成本和安全风险。The invention couples the air compressor, the air expander and the power generation equipment through the flexible control device, and completes the electric energy storage through the working process of "electric energy-compressor-air molecular potential energy-expander-electrical energy", and the electricity storage efficiency is high. , which avoids the energy level loss caused by the conversion of electricity into heat in electric boilers. Compared with the water tank heat storage technology and the steam turbine steam process transformation technology, it expands the adjustment capacity and application scenarios. Compared with the electrochemical battery energy storage technology, Increased service life, reduced costs and safety risks.

附图说明Description of drawings

图1是本发明的系统示意图。FIG. 1 is a schematic diagram of the system of the present invention.

图中：In the picture:

1-一级压缩机 2-一级冷却器 3-二级压缩机 4-二级冷却器 5-气液转换装置 6-液体空气储罐 7-一级加热器 8-一级膨胀机 9-二级加热器 10-二级膨胀机 11-储热系统冷罐 12-储热系统热 罐 13-第一阀门 14-第二阀门 15-发电机组 16-灵活性控制装置1- primary compressor 2- primary cooler 3- secondary compressor 4- secondary cooler 5- gas-liquid conversion device 6- liquid air storage tank 7- primary heater 8- primary expander 9- Secondary heater 10 - Secondary expander 11 - Heat storage system cold tank 12 - Heat storage system hot tank 13 - First valve 14 - Second valve 15 - Generator set 16 - Flexibility control device

具体实施方式Detailed ways

下面结合附图和具体实施方式对本发明作进一步详细说明，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. The specific embodiments described herein are only used to explain the present invention, and are not intended to limit the present invention.

如图1所示，本实施例一种提高电力灵活性的系统，由一级压缩机1、一级冷却器2、二级压缩机3、二级冷却器4、气液转换装置5、液体空气储罐6、一级加热器7、一级膨胀机8、二级加热器9、二级膨胀机10、储热系统冷罐11、储热系统热罐12、第一阀门13、第二阀门14、发电机组15和灵活性控制装置16组成。As shown in FIG. 1, a system for improving power flexibility in this embodiment consists of a primary compressor 1, a primary cooler 2, a secondary compressor 3, a secondary cooler 4, a gas-liquid conversion device 5, a liquid Air storage tank 6, primary heater 7,primary expander 8,secondary heater 9,secondary expander 10, heat storage system cold tank 11, heat storage system hot tank 12,first valve 13, second Thevalve 14, the generator set 15 and theflexibility control device 16 are composed.

一级压缩机1出口依次连通一级冷却器2高温侧入口、一级冷却器2高温侧出口、二级压缩机3、二级冷却器4高温侧入口、二级冷却器4高温侧出口、气液转换装置5降温液化侧入口、气液转换装置5降温液化侧出口和液体空气储罐6入口；液体空气储罐6出口依次连通气液转换装置5冷能回收侧入口、气液转换装置5冷能回收侧出口、一级加热器7低温侧入口、一级加热器7低温侧出口、一级膨胀机8、二级加热器9低温侧入口、二级加热器9低温侧出口和二级膨胀机10；储热系统冷罐11出口通过第一阀门13与一级冷却器2低温侧入口和二级冷却器4低温侧入口连通，一级冷却器2低温侧出口和二级冷却器4低温侧出口与储热系统热罐12入口连通，储热系统热罐12出口通过第二阀门14与一级加热器7高温侧入口和二级加热器9高温侧入口连通，一级加热器7高温侧出口和二级加热器9高温侧出口与储热系统冷罐11入口连接；灵活性控制装置16接受需求信号，并与发电机组15、外部电网、一级压缩机1、二级压缩机3、一级膨胀机8和二级膨胀机10设有电路连接。The outlet of the primary compressor 1 is sequentially connected to the high temperature side inlet of the primary cooler 2, the high temperature side outlet of the primary cooler 2, the secondary compressor 3, the high temperature side inlet of the secondary cooler 4, the high temperature side outlet of the secondary cooler 4, The inlet of the cooling and liquefaction side of the gas-liquid conversion device 5, the outlet of the cooling and liquefied side of the gas-liquid conversion device 5, and the inlet of the liquid air storage tank 6; 5. Cold energy recovery side outlet, primary heater 7 low temperature side inlet, primary heater 7 low temperature side outlet,primary expander 8,secondary heater 9 low temperature side inlet,secondary heater 9 low temperature side outlet and two Stage expander 10; the outlet of the cold tank 11 of the heat storage system communicates with the low temperature side inlet of the primary cooler 2 and the low temperature side inlet of the secondary cooler 4 through thefirst valve 13, and the low temperature side outlet of the primary cooler 2 and the secondary cooler 4. The low temperature side outlet is communicated with the inlet of the heat storage system hot tank 12, and the outlet of the heat storage system hot tank 12 is communicated with the high temperature side inlet of the primary heater 7 and the high temperature side inlet of thesecondary heater 9 through thesecond valve 14, and the primary heater 7 The high temperature side outlet and thesecondary heater 9 The high temperature side outlet is connected to the inlet of the cold tank 11 of the heat storage system; theflexibility control device 16 receives the demand signal, and is connected to thegenerator set 15, the external power grid, the primary compressor 1, the secondary compressor The machine 3, theprimary expander 8 and thesecondary expander 10 are provided with circuit connections.

本实施例一种提高电力灵活性的系统可以按照以下储能模式和释能模式运行。The system for improving power flexibility in this embodiment can operate in the following energy storage mode and energy release mode.

储能模式：发电机组15需要降低电输出功率时，开启储能模式，打开第一阀门13，关闭第二阀门14；灵活性控制装置16根据需求信号选择使用发电机组15发电量或外部电网电量驱动一级压缩机1和二级压缩机3，或者同时使用这两部分电量，常温常压空气经一级压缩机1压缩后进入一级冷却器2，再经二级压缩机3压缩后进入二级冷却器4成为常温高压空气，储热介质由储热系统冷罐11经第一阀门13进入一级冷却器2和二级冷却器4冷却空气，得到的高温储热介质储存在储热系统热罐12中，常温高压空气经过气液转换装置5进行降温液化，低温液态空气进入液体空气储罐6储存。Energy storage mode: when thegenerator set 15 needs to reduce the electrical output power, the energy storage mode is turned on, thefirst valve 13 is opened, and thesecond valve 14 is closed; theflexibility control device 16 selects to use the power generation of thegenerator set 15 or the power of the external grid according to the demand signal Drive the first-stage compressor 1 and the second-stage compressor 3, or use both parts of electricity at the same time. The normal temperature and normal pressure air is compressed by the first-stage compressor 1 and then enters the first-stage cooler 2, and then is compressed by the second-stage compressor 3 and enters the The secondary cooler 4 becomes normal temperature and high pressure air, and the heat storage medium enters the primary cooler 2 and the secondary cooler 4 from the heat storage system cold tank 11 through thefirst valve 13 to cool the air, and the obtained high temperature heat storage medium is stored in the heat storage system. In the system hot tank 12, the normal temperature and high pressure air is cooled and liquefied through the gas-liquid conversion device 5, and the low-temperature liquid air enters the liquid air storage tank 6 for storage.

释能模式：发电机组15需要提高电输出功率时开启释能模式，关闭第一阀门13，打开第二阀门14；低温液态空气从液体空气储罐6流出，经气液转换装置5进行冷能回收后生成的常温高压空气进入一级加热器7加热，加热后的空气进入一级膨胀机8发电，再进入二级加热器9加热，加热后的空气进入二级膨胀机10发电，二级膨胀机10出口为常压常温空气，排入周围环境，电量通过灵活性控制装置16输送至外部电网，温储热介质由储热系统热罐12经第二阀门14进入一级加热器7和二级加热器9加热空气，得到的低温储热介质随后储存在储热系统冷罐11中。Energy release mode: when the generator set 15 needs to increase the electrical output power, the energy release mode is turned on, thefirst valve 13 is closed, and thesecond valve 14 is opened; The normal temperature and high pressure air generated after recovery enters the primary heater 7 for heating, the heated air enters theprimary expander 8 to generate electricity, and then enters thesecondary heater 9 for heating, and the heated air enters the secondary expander 10 to generate electricity, and thesecondary expander 10 generates electricity. The outlet of theexpander 10 is normal pressure and normal temperature air, which is discharged into the surrounding environment, and the electricity is transported to the external power grid through theflexibility control device 16. Thesecondary heater 9 heats the air, and the resulting low temperature heat storage medium is then stored in the heat storage system cold tank 11 .

尽管上面结合附图对本发明进行了描述，但本发明并不局限于上述的具体实施方式，上述的具体实施方式仅仅是示意性的，而不是限制性的，本领域的普通技术人员在本发明的启示下，在不脱离本发明宗旨的情况下，还可以作出很多变形，这些均属于本发明的保护之内。凡利用此构思对本发明进行非实质性的改动，均应属于侵犯本发明保护范围的行为。Although the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are only illustrative rather than restrictive. Under the inspiration of the present invention, many modifications can be made without departing from the spirit of the present invention, which all belong to the protection of the present invention. Any insubstantial modification of the present invention by using this concept shall be regarded as an act infringing the protection scope of the present invention.

Claims (8)

1. A system for increasing power flexibility, comprising: the system is composed of a multi-stage compressor, a multi-stage cooler, a gas-liquid conversion device (5), a liquid air storage tank (6), a multi-stage heater, a multi-stage expander, a heat storage system cold tank (11), a heat storage system hot tank (12), a first valve (13), a second valve (14), a generator set (15) and a flexibility control device (16);

the multistage compressors correspond to the multistage coolers one by one, and the corresponding coolers are connected in series behind each stage of compressor; the multistage heaters correspond to the multistage expanders one by one, and the corresponding expanders are connected in series behind each stage of heater; the outlet of the first-stage compressor is sequentially communicated with a high-temperature side inlet of a first-stage cooler, a high-temperature side outlet of the first-stage cooler, a second-stage compressor, a high-temperature side inlet of a second-stage cooler, a high-temperature side outlet of a second-stage cooler, a cooling liquefaction side inlet of the gas-liquid conversion device (5), a cooling liquefaction side outlet of the gas-liquid conversion device (5) and an inlet of a liquid air storage tank (6); an outlet of the liquid air storage tank (6) is sequentially communicated with a cold energy recovery side inlet of the gas-liquid conversion device (5), a cold energy recovery side outlet of the gas-liquid conversion device (5), a low-temperature side inlet of the first-stage heater, a low-temperature side outlet of the first-stage heater, the first-stage expander, a low-temperature side inlet of the second-stage heater, a low-temperature side outlet of the second-stage heater, the second-stage expander, a low-temperature side inlet of the heater to the last stage, a low-temperature side outlet of the last-stage heater and the; an outlet of a cold tank (11) of the heat storage system is communicated with a low-temperature side inlet of a first-stage cooler, a low-temperature side inlet of a second-stage cooler and a low-temperature side inlet of a last-stage cooler through a first valve (13), a low-temperature side outlet of the first-stage cooler, a low-temperature side outlet of the second-stage cooler and a low-temperature side outlet of the last-stage cooler are communicated with an inlet of a hot tank (12) of the heat storage system, an outlet of the hot tank (12) of the heat storage system is communicated with a high-temperature side inlet of a first-stage heater, a high-temperature side inlet of a second-stage heater and a high-temperature side inlet of the last-stage heater through a second valve (14), and a high-temperature side outlet of the first-stage heater, a high; the flexibility control device (16) receives the demand signal and is in circuit connection with the generator set (15), an external power grid, the multi-stage compressor and the multi-stage expander; the system is suitable for power plants with flexibility requirements and power plants needing stable output, can improve the quality of electric energy of the power plants, and improves the stability of a power system.

2. A system for increasing power flexibility as defined in claim 1, wherein: the flexibility control device (16) selects to use the power generation amount of the power generator set (15) or the electric quantity of an external power grid to drive the compressor according to the demand signal, or uses the two electric quantities to drive the compressor at the same time.

3. A system for increasing power flexibility as defined in claim 1, wherein: and the flexibility control device (16) controls the start and stop of the expansion machine according to the demand signal and transmits the power generation amount of the expansion machine to an external power grid.

4. A system for increasing power flexibility as defined in claim 1, wherein: the multistage compressor is two-stage, is one-level compressor (1) and second compressor (3) respectively, the multistage cooler is two-stage, is one-level cooler (2) and second cooler (4) respectively.

5. A system for increasing power flexibility as defined in claim 1, wherein: the multi-stage heater is two-stage, and is respectively a first-stage heater (7) and a second-stage heater (9), and the multi-stage expander is two-stage, and is respectively a first-stage expander (8) and a second-stage expander (10).

6. A system for increasing power flexibility as defined in claim 1, wherein: the heat storage system cold tank (11) and the heat storage system hot tank (12) store heat generated in the air compression process, and are used for heating low-temperature air and then pushing the expansion machine to generate electricity in the energy release mode.

7. A system for increasing power flexibility as defined in claim 1, wherein: the peak regulation capacity and the response speed of the unit can be improved when the device is applied to a coal-fired power plant, the frequency modulation performance of the unit is improved, the stability of the electric output power can be improved when the device is applied to a photovoltaic power plant and a wind power plant, and the consumption capacity of a power grid to new energy is improved.

8. A method of operating a system for increasing flexibility of electricity according to any one of claims 1 to 7, wherein: the energy storage device comprises an energy storage mode and an energy release mode, and specifically comprises the following steps:

an energy storage mode: when the generator set (15) needs to reduce the electric output power, the energy storage mode is started, the first valve (13) is opened, and the second valve (14) is closed; the flexibility control device (16) selects to use the generated energy of the generator set (15) or the electric energy of an external power grid to drive the multi-stage compressor according to a demand signal, or uses the two electric quantities simultaneously, normal-temperature and normal-pressure air enters the first-stage cooler after being compressed by the first-stage compressor, then enters the second-stage cooler after being compressed by the second-stage compressor until entering the final-stage cooler after being compressed by the final-stage compressor to become normal-temperature and high-pressure air, a heat storage medium enters the first-stage cooler (2), the second-stage cooler (4) and the final-stage cooler from the heat storage system cold tank (11) through the first valve (13) to cool the air, the obtained high-temperature heat storage medium is stored in the heat storage system hot tank (12), the normal-temperature and high-pressure air is cooled and liquefied through the gas-liquid conversion device;

energy release mode: when the power generator set (15) needs to improve the electric output power, the energy release mode is started, the first valve (13) is closed, and the second valve (14) is opened; the low-temperature liquid air flows out from a liquid air storage tank (6), normal-temperature high-pressure air generated after cold energy recovery is carried out by a gas-liquid conversion device (5) enters a first-stage heater for heating, the heated air enters a first-stage expander for power generation and then enters a second-stage heater for heating, the heated air enters a second-stage expander for power generation until entering a final-stage heater for heating, the heated air enters the final-stage expander for power generation, normal-pressure normal-temperature air is discharged into the surrounding environment at the outlet of the final-stage expander, electric quantity is transmitted to an external power grid through a flexibility control device (16), a high-temperature heat storage medium enters a first-stage heater (7) and a second-stage heater (9) from a heat storage system hot tank (12) through a second valve (14), until the final heater heats the air, the resulting low-temperature heat storage medium is then stored in the cold tank (11) of the heat storage system.

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