Composite energy storage device for flat peak voltage stabilization of power system

Abstract

The invention discloses a composite energy storage device for peak-average voltage stabilization of an electric power system, and belongs to the technical field of design and construction of energy storage engineering structures. The invention provides the composite energy storage device for peak-average voltage stabilization of the power system, which can effectively improve the energy storage density and the conversion efficiency and obviously reduce the investment cost. The composite energy storage device comprises a gravitational potential energy storage system, a pressure potential energy storage system and a heat energy storage system, the composite energy storage device further comprises a multi-energy coupling energy storage mechanism, and the gravitational potential energy storage system and the pressure potential energy storage system are connected into a whole through the multi-energy coupling energy storage mechanism. The heat energy storage system is connected with the multi-energy coupling energy storage mechanism under the cooperation of the pressure potential energy storage system; in the operation process of the electric power system, surplus electric energy of the electric power system in the peak bottom electricity utilization period is converted into mechanical energy to be stored in the composite energy storage device, and the mechanical energy stored in the composite energy storage device in the peak top electricity utilization period is converted into electric energy to be supplied.

Description

TECHNICAL FIELD

[0001] The application relates to a composite energy storage device, in particular to a composite energy storage device for peak shaving and voltage stabilization of a power system, and belongs to the technical field of design and construction of energy storage engineering structures. BACKGROUND

[0002] Energy storage plays a key role in a new power system mainly based on new energy and with high proportion of renewable energy access. Its functions cover multiple dimensions such as energy regulation, system stability, economic improvement, etc. Firstly, it balances the intermittency of new energy and improves the power system's consumption capacity. Secondly, it enhances the stability and reliability of the power grid. Thirdly, it optimizes the economic efficiency and operation efficiency of the power system. Fourthly, it supports the technological innovation of the new power system.

[0003] At present, various types of energy storage have certain development. Based on the principle of energy conversion, mechanical energy storage with long-term energy storage characteristics has been rapidly developed because of its mature technology, high conversion efficiency, high energy density of thermal energy storage and low cost of heat storage. Pumped storage and compressed air energy storage are widely used in mechanical energy storage.

[0004] Pumped storage power station mainly includes upper reservoir, lower reservoir, water conveyance system (including surge chamber), power generation system. The site selection depends on specific topography. There should be enough height difference between the upper and lower reservoirs, and the distance-height ratio should not be too large. The construction period is long (5-8 years), the initial investment is high (the cost of single kilowatt is about 5000-8000 yuan), the water resource consumption is large, the evaporation loss accounts for 2%-5%, and the impact on the ecological environment is significant, which requires land submergence or natural river channel modification.

[0005] Compressed air energy storage power station mainly includes compressor, expander, heat exchanger, cold and hot storage tank, high-pressure gas storage, pipeline system, gate valve and pump. Compressed air energy storage has low energy density (about 2-10 kWh / m 3 ), which requires large storage space (salt cave, mine); the system efficiency is 60%-70%, which is slightly lower than that of pumped storage power station; the equipment is complex, multi-stage compression requires supporting heat exchanger, investment cost is high, and the cost of single kilowatt of hundreds of megawatt system is about 8000 yuan.

[0006] Thermal energy storage power station mainly includes electric heater, cold and hot storage tank, steam generator, steam turbine generator unit, pipeline system, gate valve and pump. If high-temperature heat storage is used, temperature-resistant materials are required, such as containers that can withstand temperatures above 300℃ for molten salt. Molten salt has certain corrosiveness to equipment, which increases the cost of equipment; the energy density of low-temperature heat storage is low, such as about 0.1 kWh / m 3 , which requires large area; heat loss is significant, and the long-term heat storage efficiency decays by 10%-15% / year. SUMMARY

[0007] The technical problem solved by the present application is to provide a composite energy storage device for peak flattening and voltage stabilization of a power system, which can effectively improve energy storage density and conversion efficiency and significantly reduce investment cost.

[0008] The technical scheme adopted to solve the above technical problem is a composite energy storage device for peak flattening and voltage stabilization of a power system, comprising a gravitational potential energy storage system, a pressure potential energy storage system and a thermal energy storage system, wherein the composite energy storage device further comprises a multi-energy coupling energy storage mechanism, the gravitational potential energy storage system and the pressure potential energy storage system are connected as a whole through the multi-energy coupling energy storage mechanism, and the thermal energy storage system is connected with the multi-energy coupling energy storage mechanism under the cooperation of the pressure potential energy storage system; during operation of the power system, the excess power of the power system during the peak power consumption period is converted into mechanical energy and stored in the composite energy storage device, and the part of the power of the power system during the peak power consumption period is converted into electrical energy by the mechanical energy stored in the composite energy storage device.

[0009] Further, the gravitational potential energy storage system is composed of at least one pumped storage power station, the pressure potential energy storage system is composed of at least one compressed air energy storage power station, the thermal energy storage system is composed of at least one thermal energy storage power station, and the multi-energy coupling energy storage mechanism is composed of a water-air coexistence coupling reservoir, one outlet end of a water delivery structure of the pumped storage power station is connected with the water-air coexistence coupling reservoir, the high-pressure gas storage of the compressed air energy storage power station is composed of the water-air coexistence coupling reservoir, and the thermal energy of the thermal energy storage power station is stored and released in the compression and expansion of air through the cooperation of the compressed air energy storage power station and the water-air coexistence coupling reservoir,

[0010] The total capacity of the water-air coexistence coupling reservoir at least meets the overall requirements of energy storage and pressure regulation.

[0011] The preferred mode of the above scheme is that the total capacity V of the water-air coexistence coupling reservoir -总 is determined according to the following public test calculation,

[0012] V -总 = V -储气 + V -调气 + V -调水 , wherein V -储气 is the high-pressure gas storage volume of the compressed air energy storage power station, the unit is m 3 ; V -调气 is the minimum value of the gas volume required for the operation of the pressure regulating chamber, the unit is m 3 ; and V -调水 is the minimum value of the water volume required for the operation of the pressure regulating chamber, the unit is m 3 .

[0013] Further, the high-pressure gas storage volume V -储气 of the compressed air energy storage power station is determined according to the following public test calculation,

[0014] V -储气 = mRT / MP0,

[0015] Wherein: m is the total gas consumption; R is the gas constant, 8.314 J / (mol·k); T is the absolute temperature (k); M is the gas molar mass; P0 is the initial pressure of the energy release (Pa).

[0016] The preferred mode of the above scheme is that the minimum value of the water volume V -调水 is determined according to the following requirements,

[0017] When the water-gas co-containment coupling reservoir completes gas storage, at this time the water level in the reservoir is the lower limit of the static working condition water level Z -静下限 , the absolute pressure head of the static working condition gas in the reservoir P0 = Z -上正 + local atmospheric pressure - Z -静下限 ; when the units of the water conveying system increase load at the same time, the water-gas co-containment coupling reservoir operates as a gas cushion type pressure regulating chamber to supplement the water volume to the pressure pipeline, at this time V 气 = V -储气 + V -调气 , so as to determine the lower limit of the water level in the reservoir to obtain the upper limit of the dynamic working condition water level in the reservoir; the volume between the static and dynamic water level limits is the minimum water volume that meets the pressure regulating operation, and the volume below the dynamic water level limit is the volume that meets the safety margin requirement, so the volume of V -调水 is the volume below the lower limit of the water level in the reservoir,

[0018] Wherein, the lower limit of the water level in the reservoir should have a corresponding safety height with the bottom plate of the pressure regulating chamber, and at least 2m as specified in the specification is taken as the value;

[0019] The minimum value of the gas volume V -调气 that meets the pressure regulating chamber operation requirement is determined according to the following requirements,

[0020] When the water-gas co-containment coupling reservoir completes energy release, at this time the water level in the reservoir is the upper limit of the static working condition water level Z -静上限 , the absolute pressure head of the static working condition gas in the reservoir P0 = Z -上正 + local atmospheric pressure - Z -静上限 ; when the units of the water conveying system shed load at the same time, the water flow in the water conveying system surges to the gas cushion type pressure regulating chamber, at this time V 气 = V -调气 , according to which the highest water level in the reservoir and the pressure at the inlet of the volute in the water conveying system are determined to obtain the upper limit of the dynamic working condition water level in the reservoir; according to the safety height requirement and the regulation guarantee requirement, the minimum gas volume that should be reserved when the gas storage reservoir operates as a pressure regulating chamber is V -调气 ,

[0021] The safety height requirement is a safety distance of the upper limit water level of the water inflow into the exhaust pipeline from the exhaust hole of the gas storage, and the adjustment guarantee requirement is a maximum value of the inlet pressure of the volute calculated according to the adjustment requirement.

[0022] Further, after confirming the basic storage capacity of the water-gas coexistence coupling storage, the effective gas storage capacity of the water-gas coexistence coupling storage needs to be rechecked, and the effective gas storage capacity of the water-gas coexistence coupling storage is rechecked according to the following formula,

[0023]

[0024] Wherein, m is the total exhaust volume; M is the molar mass of the gas, about 28.97 g / mol; R is the gas constant, 8.314 J / (mol·k); T is the absolute temperature (k); P0 is the absolute pressure (Pa) at the initial moment of energy release; P1 is the absolute pressure (Pa) at the end moment of energy release.

[0025] T is the absolute temperature (k); P0 is the absolute pressure (Pa) at the initial moment of energy release; P1 is the absolute pressure (Pa) at the end moment of energy release.

[0026] The preferred mode of the above scheme is that the compressed air energy storage power station further comprises an air compressor unit, a heat exchanger, a heater and a gas delivery pipe, a plurality of air compressors are connected in series with one heater and a plurality of heat exchangers through the gas delivery pipe, and the high-pressure gas output end of the compressed air energy storage power station is connected with the water-gas coexistence coupling storage; the heat storage and energy storage power station comprises an electric heating boiler, a heat storage tank, a cold storage tank and a gas delivery pipe, the electric heating boiler is sequentially connected with the heat storage tank and the cold storage tank through the gas delivery pipe, and the heat exchanger is sequentially connected between the heat storage tank and the cold storage tank;

[0027] When the compressed air energy storage power station cooperates with the heat storage and energy storage power station to store energy in the water-gas coexistence coupling storage or reversely output and expand to release energy and do work, both the air compression and the air expansion are segmented and graded, and the specific process is as follows,

[0028] When storing energy, the air is preheated by the waste heat of the cold storage tank, and then compressed in three or four segments, and the compressed air is cooled by the corresponding heat exchanger between the segments; when releasing energy, the compressed air is heated and expanded to do work by the hot water in the heat storage tank, and then reheated to do work again.

[0029] Further, the heat storage and energy storage power station further comprises a turbine expander, and the heat storage and energy storage power station converts heat energy into electric energy by the turbine expander.

[0030] The preferred mode of the above scheme is that the generator unit of the pumped storage power station is connected with the medium-pressure compressor unit and / or the low-pressure compressor unit for segmented and graded air compression according to needs.

[0031] Further, at least the unit technology water supply subsystem and the life water supply subsystem of the compressed air energy storage power station maintenance and operation are connected with the water treatment subsystem of the composite energy storage device respectively.

[0032] The beneficial effects of the present application are: the technical scheme provided by the present application is based on the existing gravitational potential energy storage system, pressure potential energy storage system and thermal energy storage system, the gravitational potential energy storage system and the pressure potential energy storage system are connected as a whole by setting a multi-energy coupling energy storage mechanism, and then the thermal energy storage system is connected with the multi-energy coupling energy storage mechanism under the cooperation of the pressure potential energy storage system. In this way, when the power system operates in the peak bottom power consumption period, the excess power of the power system can be converted into mechanical energy and stored in the composite energy storage device, and when the power system operates in the peak top power consumption period, the part of the power system overload needs can be converted into electrical energy by the mechanical energy stored in the composite energy storage device. Thus, the energy storage density and conversion efficiency can be effectively improved. Furthermore, the composite energy storage device of the present application fully utilizes the existing energy storage system and changes it into each subsystem, thereby significantly reducing the investment cost. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a simplified frame structure diagram of the composite energy storage device for peak flattening and voltage stabilization of the power system of the present application;

[0034] Figure 2 It is a composition and principle diagram of the composite energy storage device for peak flattening and voltage stabilization of the power system of the present application;

[0035] Figure 3 It is a principle process flow diagram of the composite energy storage device for peak flattening and voltage stabilization of the power system of the present application;

[0036] Figure 4 It is an energy storage operation condition process flow diagram of the composite energy storage device for peak flattening and voltage stabilization of the power system of the present application;

[0037] Figure 5 It is a release energy operation condition process flow diagram of the composite energy storage device for peak flattening and voltage stabilization of the power system of the present application;

[0038] Figure 6 It is a diagram of each water level of the water-gas coexistence coupling reservoir involved in the composite energy storage device for peak flattening and voltage stabilization of the power system of the present application.

[0039] In the figure, the marks are: water-gas coexistence coupling reservoir 1, air compressor 2, heat exchanger 3, heater 4, electric heating boiler 5, heat storage tank 6, cold storage tank 7, medium pressure compressor set 8, low pressure compressor set 9, generator set 10, unit technology water supply subsystem 11, life water supply subsystem 12, turbine expander 13. DETAILED DESCRIPTION

[0040] As Figures 1-6 The composite energy storage device for peak load leveling and voltage stabilization of power system can effectively improve the energy storage density and conversion efficiency, and significantly reduce the investment cost. The composite energy storage device for peak load leveling and voltage stabilization of power system comprises a gravitational potential energy storage system, a pressure potential energy storage system and a thermal energy storage system. The composite energy storage device further comprises a multi-energy coupling energy storage mechanism. The gravitational potential energy storage system and the pressure potential energy storage system are connected as a whole through the multi-energy coupling energy storage mechanism. The thermal energy storage system is connected with the multi-energy coupling energy storage mechanism under the cooperation of the pressure potential energy storage system. During the operation of the power system, the surplus electric energy of the power system during the peak load period is converted into mechanical energy and stored in the composite energy storage device. The part of the electric energy of the power system during the peak load period needs to be converted into electric energy by the mechanical energy stored in the composite energy storage device. The technical scheme provided by the application is based on the existing gravitational potential energy storage system, pressure potential energy storage system and thermal energy storage system. The gravitational potential energy storage system and the pressure potential energy storage system are connected as a whole through the multi-energy coupling energy storage mechanism. Then, the thermal energy storage system is connected with the multi-energy coupling energy storage mechanism under the cooperation of the pressure potential energy storage system. In this way, when the power system operates during the peak load period, the surplus electric energy of the power system can be converted into mechanical energy and stored in the composite energy storage device. When the power system operates during the peak load period, the part of the electric energy of the power system needs to be converted into electric energy by the mechanical energy stored in the composite energy storage device. Thus, the energy storage density and conversion efficiency can be effectively improved. Furthermore, the composite energy storage device fully utilizes the existing energy storage system and changes it into each sub-system, thereby significantly reducing the investment cost.

[0041] Accordingly, in combination with the prior art, the gravity potential energy storage system of the application is composed of at least one pumped storage power station, the pressure potential energy storage system is composed of at least one compressed air energy storage power station, the thermal energy storage system is composed of at least one thermal energy storage power station, and the multi-energy coupling storage mechanism is composed of a water-air coexistence coupling reservoir. An outlet end of the water delivery structure of the pumped storage power station is connected with the water-air coexistence coupling reservoir 1, the high-pressure gas storage of the compressed air energy storage power station is composed of the water-air coexistence coupling reservoir 1, and the thermal energy of the thermal energy storage power station is stored and released in the compression and expansion of air through the cooperation of the compressed air energy storage power station and the water-air coexistence coupling reservoir 1. In the water-air coexistence coupling reservoir, the total capacity at least meets the overall requirements of energy storage and pressure regulation. More specifically, the compressed air energy storage power station of the application further comprises an air compressor set 2, a heat exchanger 3, a heater 4 and a gas delivery pipe. Multiple air compressor sets 2 are connected in series with one heater 4 and multiple heat exchangers 3 through the gas delivery pipe, and the high-pressure gas output end of the compressed air energy storage power station is connected with the water-air coexistence coupling reservoir 1. The thermal energy storage power station of the application comprises an electric heating boiler 5, a thermal storage tank 6, a cold storage tank 7 and a gas delivery pipe. The electric heating boiler 5 is sequentially connected with the thermal storage tank 6 and the cold storage tank 7 through the gas delivery pipe, and the heat exchanger 3 is sequentially connected between the thermal storage tank 6 and the cold storage tank 7. When the compressed air energy storage power station inputs compressed air into the water-air coexistence coupling reservoir 1 or reversely outputs the expanded released energy from the water-air coexistence coupling reservoir 1 to do work, the segmented and staged compression or the segmented and staged expansion is adopted. In the specific process, when the energy is stored, the air is preheated by the waste heat of the cold storage tank 7, and then compressed in three or four segments. The compressed air is cooled by the corresponding heat exchanger 3 between the segments. When the energy is released, the compressed air is heated and expanded to do work by the hot water in the thermal storage tank 6, and then reheated to do work again. At this time, the thermal energy storage power station of the application adopts a turbine expander 13 to replace the existing steam generator and steam turbine generator set of the thermal energy storage power station, realizes the purpose of converting thermal energy into electric energy by the turbine expander 13 of the thermal energy storage power station, and connects the generator set 10 of the pumped storage power station with the medium-pressure compressor set 8 and / or the low-pressure compressor set 9 of the segmented and staged compressed air according to the needs, and then connects the unit technical water supply subsystem 11 and the life water supply subsystem 12 of the compressed air energy storage power station with the water treatment subsystem of the composite energy storage device respectively, so as to achieve the purpose of maximizing the investment.

[0042] As the key structure improved by the application, the design of the water-air coexistence coupling reservoir is the key point of system coupling. In order to make the reservoir capacity meet the reservoir capacity requirements of the compressed air energy storage system and the adjustment and guarantee requirements of the pumped storage system under various working conditions, the total capacity V of the water-air coexistence coupling reservoir 1 of the application is -总 According to the following public test calculation,

[0043] V-总 = V -储气 + V -调气 + V -调水 , wherein V -储气 is the high-pressure gas storage volume of the compressed air energy storage power station, in units of m 3 ; V -调气 is the minimum value of the gas volume required to meet the operating requirements of the surge chamber, in units of m 3 ; V -调水 is the minimum value of the water volume required to meet the operating requirements of the surge chamber, in units of m 3 . The high-pressure gas storage volume V -储气 of the compressed air energy storage power station is determined according to the following public test calculation,

[0044] V -储气 = mRT / MP0,

[0045] wherein: m is the total gas consumption; R is the gas constant, 8.314 J / (mol·k); T is the absolute temperature (k); M is the molar mass of the gas; P0 is the pressure at the initial moment of energy release (Pa). At this time, the minimum value of the water volume V -调水 required to meet the operating requirements of the surge chamber is determined according to the following requirements,

[0046] When the water-gas co-containment coupling reservoir completes gas storage, at this time the water level in the reservoir is the lower limit of the water level in the static working condition Z -静下限 , the absolute pressure head of the gas in the static working condition reservoir P0 = Z -上正 + local atmospheric pressure - Z -静下限 ; when the units of the water conveying system increase load at the same time, the water-gas co-containment coupling reservoir operates as a gas cushion surge chamber to supplement the water volume to the pressure pipeline, at this time V 气 = V -储气 + V -调气 , to determine the boundary calculation reservoir minimum water level to obtain the lower limit of the water level in the dynamic working condition; the volume between the static and dynamic water level limits is the minimum water volume required to meet the surge operation, the volume below the dynamic water level limit is the volume required to meet the safety margin requirement, so the volume of V -调水 is the volume below the lower limit of the water level in the static working condition,

[0047] wherein the lower limit of the water level in the reservoir should have a corresponding safety height with the bottom plate of the surge chamber, and at least 2m as specified in the specification is taken as the value;

[0048] The minimum value of the gas volume V -调气 required to meet the operating requirements of the surge chamber is determined according to the following requirements,

[0049] When the water-gas co-containment coupling reservoir ends energy release, at this time the water level in the reservoir is the upper limit of the water level in the static working condition Z -静上限, the absolute pressure head of indoor gas in static working condition P0=Z -上正 + local atmospheric pressure - Z -静上限 When the units in the water supply system are simultaneously unloaded, the water in the water supply system flows to the air cushion pressure regulating reservoir. At this time, V 气 =V -调气 Based on this, the maximum water level in the reservoir and the volute inlet pressure in the water delivery system are calculated to obtain the upper limit of the water level in the dynamic working condition; based on the safety height requirements and regulation guarantee requirements, the minimum gas volume that should be reserved when the gas storage reservoir is used as a surge chamber is obtained, which is V -调气 ,

[0050] Among them, the safety height requirement is the safe distance between the upper water level of the exhaust pipe and the exhaust port of the gas storage reservoir to prevent water from entering the exhaust pipe, and the regulation guarantee requirement is the maximum value of the volute inlet pressure calculated to meet the regulation requirements. Furthermore, after confirming the basic storage capacity of the water-gas co-container coupling reservoir, it is necessary to review its effective gas storage capacity during operation. The effective gas storage capacity of the water-gas co-container coupling reservoir is reviewed according to the following formula:

[0051]

[0052] Where: m is the total exhaust volume; M is the gas molar mass, which is approximately 28.97 g / mol for air; R is the gas constant, 8.314 J / (mol·k);

[0053] T is the absolute temperature (K); P0 is the absolute pressure at the beginning of energy release (Pa); P1 is the absolute pressure at the end of energy release (Pa).

[0054] In summary, the technical solution provided by this application also has the following advantages:

[0055] For pumped storage, the compressed air storage reservoir is connected to the water diversion pipeline to form a water-gas co-containment cavity, which becomes an air cushion type surge chamber. It can well adapt to the characteristics of high head of pumped storage power station, large fluctuation of water level in the upper reservoir and low water pressure at the end of low-pressure water diversion pipeline. It has better hydraulic performance, operation regulation performance and working condition conversion speed. At the same time, it has many advantages such as convenient construction and transportation, good adaptability to terrain and little impact on the surface natural environment.

[0056] For compressed air energy storage, on the one hand, the water pumping and storage upper reservoir is connected with a water diversion pipeline at the bottom, and the high water level of the water pumping and storage upper reservoir forms a pressure source with small pressure change for the gas in the reservoir, thereby converting the constant volume of the conventional gas storage reservoir into a running mode with changed volume but relatively constant pressure, greatly reducing the cushion gas volume of the gas storage reservoir, improving the utilization rate and energy storage density of the volume of the gas storage reservoir, avoiding the process of expansion and then compression of the high-pressure air into the reservoir during energy storage, and reducing abnormal temperature rise; during energy release, the relatively constant pressure enables the expander set to basically work in the optimal efficiency range, thereby improving the conversion efficiency of the system.

[0057] For thermal energy storage and energy storage, on the one hand, the energy release system thereof shares the expander of the compressed air energy storage, thereby eliminating the need for a steam generator and a steam turbine generator set and reducing equipment investment. On the other hand, the medium-temperature hot water obtained after heat exchange of the heat generated by compressed air is further heated by an electric boiler, thereby improving the grade of heat and further improving the conversion efficiency of the system during energy release.

[0058] In terms of saving engineering investment, part of the process facilities, access systems and outgoing lines, transformers and switch stations, production auxiliary facilities and construction temporary facilities can be designed and constructed in a unified manner for common use, thereby reducing repeated investment and significantly reducing the engineering cost.

[0059] In terms of system response speed, the electrode boiler can be steplessly adjusted in the range of 0-100%, and can reach the set power with an accuracy of more than 99% within tens of seconds, thereby improving the response speed to the demand for grid regulation.

[0060] The technical solutions of the present application are further described below through specific embodiments.

[0061] The technical problem solved by the present application is that the three types of energy storage, i.e., water pumping and storage, compressed air energy storage and thermal energy storage, are integrated into a comprehensive energy storage system, the coupling of the three energy forms of gravitational potential energy of water, pressure potential energy of compressed air and thermal energy of hot water is achieved, the energy storage density, conversion efficiency and energy utilization rate of the system are improved, the engineering investment is reduced, and the operation flexibility is improved. The specific description is as follows.

[0062] The multi-energy coupling energy storage system mainly comprises an energy storage system, an energy transmission system, an energy conversion system and a control and auxiliary system, and the composition and principle of the multi-energy coupling energy storage system are shown in Figure 1 .

[0063] The energy storage system includes: a gravity potential energy storage system composed of an upper reservoir and a lower reservoir, the regulating reservoir capacity of the upper reservoir and the lower reservoir and the height difference between the two are key indicators reflecting the energy storage density and the energy storage amount; a pressure potential energy storage system mainly composed of a compressed air storage reservoir, the pressure and the reservoir capacity of the storage reservoir are key indicators reflecting the energy storage density and the energy storage amount; a thermal energy storage system mainly composed of a heat storage tank and a cold storage tank, the temperature and the specific heat capacity of the heat storage medium and the volume of the storage tank are key indicators reflecting the energy storage density and the energy storage amount.

[0064] The energy transmission system includes: a water transmission system connecting the upper and lower reservoirs, including a water diversion tunnel, a pressure pipeline, and a tail water tunnel, to solve the water hammer problem caused by hydraulic inertia during the working condition conversion process, a pressure regulating chamber is usually arranged; a high-pressure pipeline connecting the gas storage reservoir and the energy conversion equipment; a cold and hot pipeline connecting the heat storage tank, the cold storage tank, the heat exchanger and the heater; the heat exchanger is an important energy transmission equipment, in the energy storage stage, the high-temperature and high-pressure air is decoupled into high-pressure and low-temperature air and high-temperature heat storage medium for separate storage, and in the energy release stage, the high-pressure and low-temperature air and the thermal energy are coupled to drive the expander to work.

[0065] The energy conversion system includes: a water pump turbine set of pumped storage, which converts electrical energy into gravitational potential energy of water during energy storage, and converts gravitational potential energy of water into electrical energy during energy release; an air compressor set, which converts electrical energy into pressure potential energy of high-pressure air during energy storage, and generates heat energy during air compression; an air expander set, which couples the pressure potential energy of compressed air and the heat energy in the heat storage system to convert into electrical energy during energy release; an electric heating boiler, which converts electrical energy into heat energy in the heat storage system during energy storage.

[0066] The control and auxiliary system includes: various gate valves on the pipelines of the energy transmission system, including the water transmission system butterfly valve, the working gate, the emergency gate, the control valve of the high-pressure gas pipeline, the control valve and the water pump on the cold and hot water pipeline, and the unit technical water supply system, the compressed air system, the water treatment system, the ventilation and heating system and the like which provide technical support for the operation and maintenance of the main equipment.

[0067] Due to the high gas storage pressure of the multi-energy coupling energy storage system, both compression and expansion adopt a staged scheme. During energy storage by compression, the air is first preheated by the waste heat of the low-temperature water tank, and then compressed in three or four stages, and the heat exchanger is used to reduce the temperature of the compressed air between stages. During energy release by expansion, the compressed air is heated by the hot water in the heat tank, and then expanded to do work, and then reheated to do work again.

[0068] The principle process flow of the multi-energy coupling energy storage system is divided into energy storage operation condition and energy release operation condition, which is described as follows, and the compression and expansion are taken as an example of three stages.

[0069] The energy storage operation condition process flow of the multi-energy coupling energy storage system is shown in Figure 3: The pumped storage unit converts electric energy into rotating energy of the unit, and the water in the lower reservoir is raised to the upper reservoir through the water delivery system to realize the conversion of electric energy into gravitational potential energy of the reservoir water; the air is preheated and enters the first stage compression, the compressed air enters the heat exchanger to reduce the temperature and then enters the second stage compression, after the second stage compression, the air enters the second stage heat exchanger to reduce the temperature, and then enters the third stage compression and the third stage heat exchange; the compressed air after heat exchange and temperature reduction enters the gas storage, the compressed air entering the gas storage drives the water in the water-air compatible reservoir, i.e. the water-air compatible coupling reservoir mentioned above, to enter the upper reservoir through the water delivery system of the pumped storage power station; when the compressed air energy storage system operates, the electric energy is converted into the pressure potential energy of the compressed air in the gas storage, the gravitational potential energy of part of the water in the upper reservoir, and the heat energy generated in the compression process; for the heat storage and energy storage system, the heat generated in the air compression process is transferred to the heat storage medium through the heat exchanger, stored in the medium temperature tank, and further heated by the electric heating boiler to store in the high temperature tank, realizing the conversion from electric energy to heat energy, and obtaining higher grade heat energy at the same time.

[0070] The water in the upper reservoir flows to the lower reservoir through the water delivery system, drives the pumped storage unit to do work, and realizes the conversion of the gravitational potential energy of the reservoir water into electric energy; part of the water in the upper reservoir enters the water-air compatible gas storage through the water delivery system, drives the gas storage to exhaust, the high-pressure air discharged is heated by the heat storage medium in the medium temperature tank through the heat exchanger, and then is heated by the heat storage medium in the high temperature tank for the second time to further increase the temperature, and then enters the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder of the turbine expander in turn to do work, and the exhaust of the high-pressure cylinder and the medium-pressure cylinder is re-heated by the heat exchanger using the medium in the medium temperature tank, and the turbine expander works to convert part of the gravitational potential energy of the reservoir water, the pressure potential energy of the compressed air and the heat energy of the heat storage system into electric energy; for the heat storage and energy storage system, the compressed air is first heated by the medium temperature medium, and then heated by the high temperature medium, and the staged heating fully utilizes heat energy of different grades, and has higher conversion efficiency.

[0071] The reservoir capacity of the upper reservoir should meet the requirements of the water-air compatible reservoir in addition to the conventional requirements of the pumped storage regulation reservoir capacity, water loss standby reservoir capacity, etc., and the increased reservoir capacity is determined according to V-gas storage.

[0072] The design of the water-air compatible reservoir is the key of the system coupling, and the reservoir capacity should meet the requirements of the compressed air energy storage system and the regulation and guarantee requirements of the pumped storage system under various working conditions. Since the water-air compatible reservoir of the present application meets the requirements of energy storage and pressure regulation at the same time, the stable gas volume, the corresponding maximum pressure and the minimum surge cannot be calculated according to the method of the "Design Specification for Air Cushion Type Surge Chamber of Hydropower Station". The total volume of the water-air compatible reservoir is V -总 , the gas storage volume of the compressed air energy storage is V -储气 , and the minimum values of the gas and water volume meeting the operation requirements of the surge chamber are V 调气 and V-调水 , V -总 = V -储气 + V -调气 + V -调水 . V-adjusted volume of gas is the volume of the gas storage above the upper limit of the water level in the static operating chamber, V-adjusted volume of water is the volume of the gas storage below the lower limit of the water level in the static operating chamber, and V-gas storage is the volume of the gas storage between the upper and lower limits of the water level in the static operating chamber. According to the composition and operating control conditions of the multi-energy coupling energy storage system, the volume of each part is determined as follows.

[0073] The cross-sectional area of the gas storage should be greater than the Tomlinson critical stable cross-sectional area, and the diameter of the gas storage is determined accordingly.

[0074] The normal water level and dead water level of the upper reservoir are Z -上正 , Z -上死 , respectively, and the normal water level and dead water level of the lower reservoir are Z -下正 , Z -下死 .

[0075] The volume of the gas storage V-gas storage is calculated as follows: for a constant volume variable pressure gas storage, the pressure is reduced from P0 to P1, and the calculation method is: V = m / (ρ0-ρ1), where m is the total gas consumption, ρ0 is the gas density at the beginning of energy release, and ρ1 is the gas density at the end of energy release. The density formula of ideal gas is: ρ = PM / RT, P is the absolute pressure; M is the molar mass of the gas, about 28.97 g / mol; R is the gas constant, and T is the absolute temperature (k). For the temperature of the gas, the temperature of the gas storage at P0 is the temperature of the gas T0, which can be obtained by numerical analysis method according to the arrangement of the gas storage; during the exhaust process of the gas storage, the gas expands and absorbs heat, and the temperature decreases, and the temperature of the gas storage at the end of energy release T1 can be obtained according to the ideal gas state equation. According to the above formula, the volume of the constant volume variable pressure gas storage can be obtained.

[0076] When a constant pressure operation mode is used, the pressure change is small, and the volume gradually decreases during the exhaust process, so the temperature of the gas can be considered as constant, and the volume of the gas storage is calculated as follows:

[0077] V -储气 = mRT / MP0,

[0078] where:

[0079] m is the total gas consumption;

[0080] R is the gas constant, 8.314 J / (mol·k);

[0081] T is the absolute temperature (k);

[0082] M is the molar mass of the gas;

[0083] P0 is the pressure (Pa) at the initial moment of energy release.

[0084] V -调水 : The gas storage is completed, at which time the indoor water level is the static working condition indoor water level lower limit Z-static lower limit, the absolute pressure head of the static working condition indoor gas P0 = Z -上正 + local atmospheric pressure - Z -静下限 . When the units of the water conveyance system in which it is located simultaneously increase the load, as the air cushion type surge chamber supplements the water volume to the pressure pipeline, as the air cushion type surge chamber operates, V 气 = V -储气 + V -调气 , the boundary is determined to calculate the minimum indoor water level, that is, the dynamic working condition indoor water level lower limit, which should have a safety height with the surge chamber bottom plate, which can be valued according to the specification 2m. The volume between the static and dynamic water level lower limit is the minimum water volume required to meet the surge operation, and the volume below the dynamic water level lower limit is the volume required to meet the safety margin, so the V-adjusted volume is the volume below the static working condition indoor water level lower limit, which can be determined.

[0085] V-adjusted gas: when the energy release of the gas storage is completed, at which time the indoor water level is the static working condition indoor water level upper limit Z-static upper limit, the absolute pressure head of the static working condition indoor gas P0 = Z -上正 + local atmospheric pressure - Z -静上限 . When the units of the water conveyance system in which it is located simultaneously shed the load, the water flow in the water conveyance system rushes to the air cushion type surge chamber, at which time V 气 = V -调气 , the boundary is determined to calculate the maximum indoor water level and the inlet pressure of the volute in the water conveyance system, that is, the dynamic working condition indoor water level upper limit, on the one hand, the upper limit water level should have a certain safety distance from the exhaust hole of the gas storage to avoid water rushing into the exhaust pipeline, on the other hand, the maximum value of the inlet pressure of the volute should meet the requirements of the regulation guarantee calculation. According to the safety height requirement and the regulation guarantee requirement, the minimum gas volume that should be reserved when the gas storage operates as a surge chamber can be obtained, that is, V -调气 .

[0086] Due to the certain height difference of the surge chamber, it operates as a variable volume and variable pressure in actual operation, on the basis of the basic reservoir capacity determined above, the effective gas storage capacity in operation still needs to be reviewed.

[0087]

[0088] Among them:

[0089] m is the total exhaust volume;

[0090] M is the molar mass of the gas, about 28.97g / mol for air;

[0091] R is a gas constant, 8.314 J / (mol-k);

[0092] T is the absolute temperature (k);

[0093] P0 is the absolute pressure at the initial moment of energy release (Pa);

[0094] P1 is the absolute pressure at the end of energy release (Pa).

[0095] In the compressed air energy storage power station, the maintenance and operation require unit technical water supply, medium pressure compressed air, low pressure compressed air, domestic water supply, heating ventilation and other subsystems. The coupling energy storage system combines raw water treatment, medium pressure and low pressure air systems, and the treated raw water can be used for compressed air energy storage and unit technical water supply system. The segmented compressed air is supplied to the medium pressure and low pressure compressed air systems, and the air compressor of the pumped storage power station is saved. The heat of the heat storage system is coupled to the compressed air to do work with the turbine expander, and the steam generator and turbine generator set of the conventional heat storage power station are saved. In the electrical system, the three types of energy storage can share the system access and outgoing line, and the transformer and switch station in the system are shared.

[0096] In addition to the above equipment, office buildings, living quarters, and infrastructure such as on-site roads for production assistance can be shared. In terms of construction, construction roads, sand processing systems, concrete mixing systems, and construction water and power supply systems can be shared.

[0097] Example 1

[0098] 1. Project Overview

[0099] A multi-energy coupling energy storage power station is located about 30 km away from the load center, which is close to the load center and has very convenient external transportation. There are many 500 kV substations around Shifang, and the conditions for interconnection are convenient. The functions of the power station are to play the roles of peak shaving, valley filling, energy storage, frequency regulation, phase modulation and emergency backup, and to ensure the safe and stable operation of the load center power grid.

[0100] According to the system planning, the pumped storage power station has a installed capacity of 1200 MW (4x300 WW) and a full-load hour of 6h, and the main buildings are composed of upper reservoir, lower reservoir, water conveyance system, underground powerhouse, switch station and water replenishment system; the compressed air energy storage power station has a installed capacity of 300 MW and a full-load hour of 4h, and mainly includes compression system, expansion system, gas storage system and heat exchange system; the heat storage energy storage system includes a 60 MW high-voltage electrode boiler with a power supply voltage of 35 kV and a high-temperature heat storage tank.

[0101] 2. Reservoir Design

[0102] According to the terrain conditions, the normal storage level of the upper reservoir is 1197 m, corresponding to a reservoir capacity of 6.65 million m3; the dead water level is 1174 m, corresponding to a reservoir capacity of 320 thousand m3; the regulated reservoir capacity is 6.33 million m3. The normal storage level of the lower reservoir is 674 m, corresponding to a reservoir capacity of 6.54 million m3; the dead water level is 644 m, corresponding to a reservoir capacity of 210 thousand m3; the regulated reservoir capacity is 6.33 million m3. According to kinetic energy calculation, the required reservoir capacity for pumped storage is 5.87 million m3, and the water loss reserve capacity is 110 thousand m3.

[0103] 3. Water and gas coexistence reservoir design

[0104] The pumped storage power station adopts 2 diversion pipelines to arrange 4 units, the center line elevation of the lower horizontal section of the pressure pipeline is 564 m, the diameter of the pressure pipeline is 5.0 m, and the top of the pressure pipeline is 564.5 m. The bottom plate elevation of the initially proposed air cushion surge chamber is 575 m. According to the “Design Code for Surge Chambers of Hydropower Stations”, the cross-sectional area of the surge chamber should be not less than 87 m2 according to the relevant parameters of the water conveyance system. The surrounding rock at the location of the surge chamber is mainly type III, and the span of the underground powerhouse is 26 m. In order to reduce the risk of surrounding rock stability control, the effective diameter of the surge chamber is calculated as 26 m, the cross-sectional area A = 531 m2, and the safety factor of the cross-sectional area is 6.0, which exceeds the requirements of the specification. According to the initially proposed surge size, the V -调水 = 11240 m3 under the control working condition.

[0105] After the energy release of the gas storage reservoir, the static water level in the chamber rises, and the absolute pressure of the corresponding gas decreases. In order to improve the system operation efficiency and increase the utilization rate of the gas storage reservoir, the difference between the static water levels is controlled, so 2 water and gas coexistence type surge chambers are set for a water conveyance system. The bottom plate elevation of the surge chamber is 575 m, plus a safety margin of 2 m, which is 577 m, which is the lower limit of the indoor water level under dynamic working condition Z -动下 , plus the occupied volume, the water level increases by 10.6 m, which is 587.6 m, which is the lower limit of the indoor water level under static working condition Z -静下 . According to this water level, the absolute pressure head of the gas in the static working condition chamber P0 = Z -上正 + local atmospheric pressure-Z -静下限 = 1197 + 9.8-587.6 = 619.2 m.

[0106] According to the preliminary selection of the turbine expander, the gas consumption is 2456 t / h, and according to the initially proposed full load hours of 4 hours, the total gas consumption is 9824 tons. Considering that the gas storage reservoir is a water and gas coexistence reservoir, the gas temperature is initially calculated as 20℃.

[0107] According to the aforementioned calculation formula, V -储气= mRT0 / P0M = 9824 x 10^3 kg x 8.314 J / (mol k) x 293.15 K / 619.2 * 9.8 * 1000 Pa / 0.02897 (kg / mol) = 136200 m3.

[0108] Since a surge chamber and gas storage are set for each water delivery system, the volume of the gas storage in a single water delivery system is 68100 m3.

[0109] According to the estimation of 68100 m3, the volume corresponding to the height of the gas storage is 128 m, and the height is 64 m when distributed to two reservoirs. The corresponding elevation is 715.6 m, and the upper limit of the water level in the static working condition chamber is Z -静上限 = Z -静下限 + 64 = 651.6 m.

[0110] According to the load rejection calculation and analysis results of the surge chamber, in order to control the maximum pressure at the inlet of the volute not to exceed the design requirement, V -调气 should be no less than 8600 m3, so the upper limit of the water level in the dynamic working condition chamber is Z -动上 = 651.6 + 8600 / 531 / 2 = 659.7 m. Considering the 2 m safety distance above the dynamic water level to the exhaust port, the top elevation of the surge chamber is 661.7 m, which can be rounded to 662 m.

[0111] According to the above preliminary size, the absolute pressure head of the gas in the static working condition chamber at the end of energy release is P1 = Z -上死 + local atmospheric pressure - Z -静上限 = 1174 + 9.8 - 651.6 = 532.2 m.

[0112] According to the reservoir capacity data and water head obtained by the above preliminary calculation, whether the mass of the gas discharged in the energy release process meets the requirements is reviewed.

[0113] m = M(P0(V -储气 + V -调气 ) - P1 x V -调气 ) / RT0 = 0.0289 kg / mol x (619.2 x 9.8 x 1000 Pa x

[0114] (68100 m3+ 8600 m3) - 532.2 x 9.8 x 1000 Pa x 8600 m3) / 8.314 J / (mol k) / 293.15 K = 4987 tons.

[0115] The total mass of the discharged gas of the two water delivery system configured gas storage is 9974 tons, which is slightly larger than the total gas consumption of 9824 tons for 4 hours of full load, with a margin of 1.5%. It is indicated that the size of the gas storage is appropriate.

[0116] 4. Reservoir capacity review

[0117] The required reservoir capacity for pumped storage is 5.87 million m3, and the water loss standby reservoir capacity is 0.11 million m3. When the energy is stored, the water in the water-air coexistence reservoir is compressed by the compressed air and is stored in the upper reservoir through the water delivery system. The corresponding volume is V -储气 = 136200 m3 = 13.62 million m3, and the total reservoir capacity requirement V -需求 = 587 + 11 + 13.6 = 611.6 million m3. The upper reservoir condition reservoir capacity is 633 million m3, which is greater than the required reservoir capacity. Among them, 0.214 million m3 is the margin of pumped storage, and the margin coefficient is 3.65%, which meets the design requirements.

[0118] 5. Compression system

[0119] Air compression adopts a 3-stage compression and intermediate cooling method to store compressed air in the gas storage reservoir. The inlet air is at room temperature and normal pressure, 20℃, and the final compressed air outlet parameters are 6.2 MPa and 40℃. The compressor operates in a variable working range of 85.5%-100%. At the same time, heat storage medium is used to recover the compression heat between each stage of the compressor.

[0120] The main process flow of the compression system is as follows:

[0121] An air filter silencer and a flow measuring device are arranged in the inlet pipeline of the first-stage air compressor, and the air enters the compressor through the inlet isolation door.

[0122] After being compressed by the first-stage air compressor, the air sequentially passes through the heat exchanger, cooler, and gas-liquid separator, and then enters the second-stage air compressor. A flow measuring device and an inlet isolation door are arranged in the air pipeline before the second-stage air compressor.

[0123] After being compressed by the second-stage air compressor, the air sequentially passes through the heat exchanger, cooler, and gas-liquid separator, and then enters the third-stage air compressor. A flow measuring device and an inlet isolation door are arranged in the air pipeline before the third-stage air compressor, and the air enters the gas storage reservoir for storage. A flow measuring device, electric isolation door, check valve, etc. are arranged in the inlet air pipeline of the gas storage reservoir.

[0124] 6. Electric heating system

[0125] One 35kV high-voltage electrode boiler is configured to heat the water in the medium-temperature tank to 250℃ and store it in the high-temperature tank.

[0126] 7. Heat storage and exchange system

[0127] According to the maximum gas storage pressure condition, a medium-temperature adiabatic technical route is selected, and a medium-temperature heat exchange method is used for heat storage and feedback. The heat exchange medium of the heat storage system is water.

[0128] The hot water temperature of the heat storage and exchange system is 220℃, the cooling water temperature is 30℃, the heat exchanger adopts a shared solution, and the heat exchange end difference is 15℃ / 10℃.

[0129] During the compression process, cold water is pressurized by a circulating water pump from the cold water spherical tank, and then passes through the main pipe through the branch cold water pipes into the various heat exchangers between the compressor outlet sections. The water temperature at each stage of heat exchange rises from 30°C to 220°C. After three stages of heat exchange, the hot water is collected into the medium-temperature hot water spherical tank through the hot main pipe. The heat exchange medium in the closed circulation system is desalted water.

[0130] During expansion power generation, hot water from the hot water tank is pumped via a circulating water pump to the corresponding three-stage heat exchanger on the expansion power generation side. After passing through the hot water main pipe, it enters the hot water branch pipes before each heat exchanger, transferring heat to the compressed air exiting the artificial cavern, heating the air from 38°C to 193.22°C. The hot water in the high-temperature tank is then used in a high-temperature heat exchanger to heat the air from 193.22°C to 230°C. The cold water after heat exchange is further cooled in a closed cooling tower before being returned to the cold water tank. In this way, the entire thermal storage system transfers the heat released between the stages of the air compression process to the air between the expander stages of the expansion power generation system, causing it to absorb heat and expand, generating power. The entire heat exchanger and tank heat storage system constitute the project's closed heat storage and exchange system.

[0131] The heat storage circulating water volume is 1881t / h. Considering that a certain margin is reserved for the storage tank, the total volume of the pressurized hot / cold tank is 7524m 3 、7524m 3 The maximum storage temperature of the medium-temperature hot tank is 210°C, with a design pressure of 2MPa; the maximum storage temperature of the high-temperature hot tank is 250°C, with a design pressure of 4MPa. Both the hot and cold tanks are insulated, with a thermal loss of no more than 1°C per day.

[0132] 8. Expansion energy release system

[0133] In the energy release and power generation stage, the high-pressure compressed air in the gas storage is used as the working fluid. After being heated by the storage and heat exchange system, it drives the air expansion energy release unit to generate electricity.

[0134] The air expander adopts a three-stage series design with double reheat, a single high-pressure cylinder, a combined medium- and low-pressure cylinder, and axial exhaust. The expander operates at a conventional speed of 3000 rpm, is directly connected to the generator, and has a full-circle intake system for the high-pressure cylinder.

[0135] The main process flow is as follows: the high-pressure air pipeline is led out from the gas storage pipeline, heated by the heater, and connected to the turbine high-pressure cylinder combined main valve (shut-off valve and regulating valve). A flow measuring device is installed on the air pipeline, and a manual isolation valve, electric gate valve, and electric pressure reducing valve are installed.

Claims

1. A composite energy storage device for peak leveling and voltage stabilization of power systems, comprising a gravity potential energy storage system, a pressure potential energy storage system, and a thermal energy storage system, characterized by: The composite energy storage device also includes a multi-energy coupling energy storage mechanism, through which the gravity potential energy storage system and the pressure potential energy storage system are connected as a whole, and the thermal energy storage system is connected to the multi-energy coupling energy storage mechanism with the cooperation of the pressure potential energy storage system; during the operation of the power system, the surplus electrical energy of the power system during the peak and off-peak power consumption periods is converted into mechanical energy and stored in the composite energy storage device, and the part of the electrical energy that is overloaded in the power system during the peak power consumption period is required to be converted into electrical energy by the mechanical energy stored in the composite energy storage device.

2. The composite energy storage device for peak leveling and voltage stabilization of a power system according to claim 1, characterized in that: The gravity potential energy storage system is composed of at least one level of pumped storage power station, the pressure potential energy storage system is composed of at least one compressed air storage power station, the thermal energy storage system is composed of at least one heat storage power station, the multi-energy coupling energy storage mechanism is composed of a water-gas co-containment coupling reservoir, one outlet end of the power generation and water delivery structure of the pumped storage power station is connected to the water-gas co-containment coupling reservoir (1), the high-pressure gas storage reservoir of the compressed air storage power station is composed of the water-gas co-containment coupling reservoir (1), and the heat energy of the heat storage power station is stored and released in the compression and expansion of air through the cooperation of the compressed air storage power station and the water-gas co-containment coupling reservoir (1). Among them, the total capacity of the water-gas co-capacity coupling reservoir should at least meet the overall requirements of energy storage and pressure regulation.

3. The composite energy storage device for peak leveling and voltage stabilization of a power system according to claim 2, characterized in that: Total capacity V of the water-gas co-container coupled reservoir (1) -总 Determined by the following public test calculation, V -总 =V -储气 +V -调气 +V -调水 , where V -储气 is the volume of the high-pressure gas storage reservoir of the compressed air energy storage power station, in m 3 ; V -调气 The minimum gas volume required to meet the surge chamber operating requirements, in m 3 ; V -调水 The minimum volume of water required to meet the surge chamber operating requirements, in m 3 .

4. The composite energy storage device for peak leveling and voltage stabilization of a power system according to claim 3 is characterized in that: The volume V of the high-pressure gas storage reservoir of the compressed air energy storage power station -储气 Determined by the following public test calculation, V -储气 =mRT / MP0, Where: m is the total gas consumption; R is the gas constant, 8.314 J / (mol·k); T is the absolute temperature (k); M is the molar mass of the gas; and P0 is the pressure at the initial moment of energy release (Pa).

5. The composite energy storage device for peak leveling and voltage stabilization of a power system according to claim 3 or 4, characterized in that: The minimum water volume V that meets the surge chamber operation requirements -调水 Confirm as follows: When the water-gas co-container coupled reservoir completes gas storage, the water level in the reservoir is the lower limit of the indoor water level under static working conditions Z -静下限 , the absolute pressure head of the gas in the static working condition is P0=Z -上正 + local atmospheric pressure - Z -静下限 When the units in the water transmission system increase their load at the same time, the air cushion surge reservoir will be used to replenish water to the pressure pipeline, and the water-gas co-container coupling reservoir will operate as an air cushion surge chamber. At this time, V 气 =V -储气 +V -调气 , in order to determine the boundary calculation of the lowest water level in the reservoir and obtain the lower limit of the water level in the dynamic working condition reservoir; the volume between the static and dynamic water level lower limits is the minimum water volume that meets the pressure regulation operation, and the volume below the dynamic water level lower limit is the volume that meets the safety margin requirements, so V -调水 The volume is the volume below the lower limit of the water level in the static working condition reservoir. The lower limit water level in the reservoir should have a corresponding safety height with the bottom plate of the surge tank, and should be at least 2m as specified in the specification; The minimum gas volume V required to meet the surge chamber operating requirements -调气 Confirm as follows: When the energy release of the water-gas co-container coupled reservoir ends, the water level in the reservoir is the upper limit of the static working condition water level Z -静上限 , the absolute pressure head of indoor gas in static working condition P0=Z -上正 + local atmospheric pressure - Z -静上限 When the units in the water supply system are simultaneously unloaded, the water in the water supply system flows to the air cushion pressure regulating reservoir. At this time, V 气 =V -调气 Based on this, the maximum water level in the reservoir and the volute inlet pressure in the water delivery system are calculated to obtain the upper limit of the water level in the dynamic working condition; based on the safety height requirements and regulation guarantee requirements, the minimum gas volume that should be reserved when the gas storage reservoir is used as a surge chamber is obtained, which is V -调气 , Among them, the safety height requirement is the safe distance between the upper limit water level to avoid water gushing into the exhaust pipe and the exhaust hole of the gas storage reservoir, and the regulation guarantee requirement is the maximum value of the volute inlet pressure calculated to meet the regulation requirements.

6. The composite energy storage device for peak leveling and voltage stabilization of a power system according to claim 5, characterized in that: After confirming the basic storage capacity of the water-gas co-container coupling reservoir, it is also necessary to review its effective gas storage capacity during operation. The effective gas storage capacity of the water-gas co-container coupling reservoir is reviewed according to the following formula: Where: m is the total exhaust volume; M is the gas molar mass, which is approximately 28.97 g / mol for air; R is the gas constant, 8.314 J / (mol·k); T is the absolute temperature (K); P0 is the absolute pressure at the beginning of energy release (Pa); P1 is the absolute pressure at the end of energy release (Pa).

7. The composite energy storage device for peak leveling and voltage stabilization of a power system according to claim 6, characterized in that: The compressed air energy storage power station further comprises an air compressor unit (2), a heat exchanger (3), a heater (4) and a gas delivery pipe. Multiple air compressor units (2) are connected in series with one heater (4) and multiple heat exchangers (3) at staggered intervals through the gas delivery pipe. The high-pressure gas output end of the compressed air energy storage power station is connected to the water-gas co-container coupling reservoir (1). The heat storage energy storage power station comprises an electric boiler (5), a heat storage tank (6), a cold storage tank (7) and a gas delivery pipe. The electric boiler (5) is connected in sequence with the heat storage tank (6) and the cold storage tank (7) through the gas delivery pipe. The heat exchanger (3) is connected in series between the heat storage tank (6) and the cold storage tank (7). The compressed air energy storage power station cooperates with the heat storage energy storage power station to compress the air and then input it into the water-gas co-container coupling reservoir (1) for energy storage or outputs it from the water-gas co-container coupling reservoir (21) in reverse to expand and release energy to do work. Both adopt segmented graded compression or segmented graded expansion. The specific process is as follows: When compressing and storing energy, the air is first preheated by the waste heat of the cold storage tank (7), and then compressed in three or four stages, with the compressed air cooled by the corresponding heat exchanger (3) between stages; when expanding and releasing energy, the hot water in the heat storage tank (6) is used to heat the compressed air to expand and perform work, and then the air is heated again to perform work.

8. The composite energy storage device for peak leveling and voltage stabilization of a power system according to claim 7, characterized in that: The heat storage and energy storage power station further comprises a turbine expander (13), and the heat storage and energy storage power station converts heat energy into electrical energy by releasing energy and performing work through the turbine expander (13).

9. The composite energy storage device for peak leveling and voltage stabilization of a power system according to claim 8, characterized in that: The generator set (10) of the pumped storage power station is connected to the medium-pressure compressor set (8) and / or the low-pressure compressor set (9) for staged and graded air compression according to needs.

10. The composite energy storage device for peak leveling and voltage stabilization of a power system according to claim 9, characterized in that: At least the technical water supply subsystem (11) and the domestic water supply subsystem (12) of the unit for maintenance and operation of the compressed air energy storage power station are respectively connected to the water treatment subsystem of the composite energy storage device.

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