Production operation method and system based on plateau isolated network

Abstract

The invention relates to the technical field of plateau isolated network production energy supply, and discloses a plateau isolated network-based production operation method and system, which comprehensively study, judge and determine the operation condition of a lithium carbonate processing plant according to the sunlight condition, the operation condition of an energy station and the state of a fused salt energy storage system. Electric energy is provided through photovoltaic, steam and part of electric energy are provided through photo-thermal, low-load operation supports the stability requirement of an isolated network, and the surplus part of photo-thermal is stored in a fused salt energy storage system through electrochemistry; needed electric energy and steam are provided through the heat release working condition of the fused salt energy storage system at night; and in combination with weather forecast conditions, planning energy storage in advance, balancing photovoltaic power supply fluctuation through electrochemical energy storage and rapidly adjusting a load shedding working condition, and adopting a photo-thermal, photovoltaic and energy storage technical route to realize isolated island operation according to a comprehensive energy integrated scheduling operation mode. Therefore, safety, stability, continuity and reliability of production energy supply of the lithium carbonate processing plant are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of plateau isolated grid production energy supply, and particularly to a production operation method and system based on a plateau isolated grid. Background Art

[0002] In the context of the booming development of the new energy industry today, lithium carbonate, as a key raw material for lithium batteries, has seen an explosive growth in market demand. The stable and efficient production of lithium carbonate processing plants is crucial for meeting this market demand, and energy supply is the core element to ensure their production. Currently, the energy supply of many lithium carbonate processing plants mainly relies on traditional energy sources, such as fossil fuels like coal and natural gas. However, this energy supply method has many drawbacks. On the one hand, the traditional energy supply is greatly affected by external factors, such as fluctuations in the international energy market and transportation conditions limitations, which makes it difficult to effectively guarantee the stability and reliability of energy supply. Once the energy supply is interrupted, it will cause a serious impact on the continuous production of lithium carbonate processing plants, leading to production stagnation and huge economic losses. On the other hand, the use cost of traditional energy is relatively high, and with the increasing global emphasis on environmental protection, the large amount of pollutants generated during the use of traditional energy, such as carbon dioxide and sulfides, impose a heavy burden on the environment and do not conform to the concept of sustainable development. At the same time, the resource reserves of traditional energy are limited, and long-term reliance on traditional energy will face the risk of resource depletion.

[0003] To solve these problems, some lithium carbonate processing plants have tried to adopt a single renewable energy source, such as solar photovoltaic or solar thermal technology. However, solar photovoltaic power supply is significantly affected by factors such as day and night and weather, and it cannot supply power stably at night or on rainy and cloudy days; while the separate solar thermal technology has deficiencies in energy storage and is difficult to meet the demand for long-term continuous energy supply. Therefore, a single renewable energy supply method is difficult to meet the requirements of lithium carbonate processing plants for safe, stable, continuous, and reliable energy supply. In addition, some existing energy supply systems lack the concept of integrated dispatching operation, and the various energy systems cannot achieve organic coordination, resulting in low energy utilization efficiency and unable to give full play to the advantages of different energy systems.

[0004] The location of Zabuye Salt Lake has extremely rich light resources, with a long annual sunshine duration and a high solar radiation intensity. Moreover, the vast land in this area provides sufficient space for the construction of large-scale solar power generation facilities. According to the natural conditions and energy demand characteristics of Zabuye Salt Lake, choosing the technical route of "solar thermal + photovoltaic + energy storage (electricity storage, heat storage)" can effectively solve the local energy supply problem and promote the sustainable development of lithium carbonate processing plants. Summary of the Invention

[0005] The object of the present invention is to solve the above-mentioned disadvantages existing in the prior art, and to provide a production operation method and system based on a plateau isolated power grid, adopting a technical route of "solar thermal + photovoltaic + energy storage (electricity storage, heat storage)", and providing a better energy supply solution for a lithium carbonate processing plant in an integrated energy integrated dispatching operation mode.

[0006] On the one hand, a production operation method based on a plateau isolated power grid is provided. The operating conditions of the lithium carbonate processing plant are comprehensively judged and determined according to the sunshine conditions, the operating conditions of the energy station, and the state of the molten salt energy storage system, including: Utilize the daylight resources during the day. The photovoltaic system provides electric energy, and the solar thermal system provides steam and part of the electric energy. The low-load operation supports the stability requirements of the isolated power grid, and the surplus part of the solar thermal energy is electrochemically stored in the molten salt energy storage system. At night, the required electric energy and steam are provided through the exothermic condition of the molten salt energy storage system. Combined with the weather forecast, energy storage is planned in advance, and the electrochemical energy storage is used to balance the photovoltaic power supply fluctuations and the rapid adjustment of the load shedding condition.

[0007] Furthermore, the operating conditions of the lithium carbonate processing plant are comprehensively judged and determined according to the sunshine conditions, the operating conditions of the energy station, and the state of the molten salt energy storage system, including: The operating modes include a continuous operation mode and a hierarchical operation mode. Among them, In the continuous operation mode, the lithium carbonate processing plant operates continuously at a load of 60% - 100%, and the load is adjusted up / down according to the energy supply capacity of the energy station and the molten salt liquid level response. In the hierarchical operation mode, the lithium carbonate processing plant operates under the conditions of shutdown state, 60% load and 100% load, and judges whether it is necessary to switch the load condition in advance according to the energy supply capacity of the energy station and the molten salt liquid level.

[0008] Preferably, the provision of electric energy by the photovoltaic system and the provision of steam and part of the electric energy by the solar thermal system further include: By configuring the installed capacity of solar thermal and photovoltaic systems, large-capacity heat storage, and rapid-response electrochemical energy storage. Among them, the photovoltaic system is used as the main power source to meet the daytime power demand, and the surplus power is preferentially used to ensure the maintenance of the electrochemical energy storage state. Part of the heat collection of the solar thermal system enters the decoupled steam generator to directly meet the steam demand and hot water demand. The heat collection is used to generate steam to drive the steam turbine to generate electricity at the base load, and at the same time, the heat demand is met through extraction steam. The remaining heat is all stored in the molten salt energy storage system and used for power supply and steam supply at night.

[0009] Furthermore, the operating conditions include a commissioning condition, a design condition, a black start condition, and a shutdown condition. Among them, the measures for power balance operation under the commissioning condition include: For the commissioning operation of the solar thermal power station, under good lighting resources, the 35MW photovoltaic power generation and the electrochemical energy storage independently form a grid to supply the electricity consumption during the commissioning of the solar thermal power station. At night, the diesel generator configured by the energy station supplies the electricity for night commissioning. For the commissioning operation of the lithium carbonate processing plant, during the temporary power consumption commissioning operation, only the photovoltaic power generation and the electrochemical energy storage of the energy station can supply the intermittent commissioning power consumption of the lithium carbonate processing plant during the day. After the commissioning of the diesel generator set is completed, the diesel generator set, the photovoltaic power station, and the electrochemical molten salt energy storage power station are networked as the commissioning power supply for the lithium carbonate processing plant and the energy station.

[0010] Preferably, the design conditions specifically include: Condition 1: According to the energy consumption requirements of the lithium carbonate processing plant, when the solar radiation energy is sufficient to provide sufficient energy for both the steam generation system and the heat storage system at the same time and the molten salt tank is not full, the energy station is in the photovoltaic or solar thermal power supply, solar thermal steam supply, and heat storage mode. Condition 2: According to the energy consumption requirements of the lithium carbonate processing plant, when the solar radiation energy is not sufficient to provide sufficient energy for both the steam generation system and the heat storage system at the same time or the molten salt tank is already full, the energy station is in the photovoltaic or solar thermal power supply and solar thermal steam supply mode. At this time, the solar thermal energy supplies the electricity for the energy station and the lithium carbonate processing plant. Condition 3: According to the energy consumption requirements of the lithium carbonate processing plant, when the solar energy resources are insufficient, the thermal energy stored in the molten salt tank can be used for power generation and steam supply. At this time, the solar thermal energy undertakes the electricity consumption of the energy station and the lithium carbonate processing plant.

[0011] More preferably, the black start condition is to start the unit when the entire lithium carbonate processing plant loses power supply. The black start condition is distinguished according to the unit status and whether there is a surplus in the heat storage system, including: Unit hot start - heat storage system with surplus condition: At this time, there is a certain surplus in the molten salt heat storage system. In the initial stage of the unit hot start, the diesel generator supplies power until the unit is rotated and loaded, then the diesel generator is shut down, and the heat storage system of the solar thermal energy is switched to supply the plant electricity of the lithium carbonate processing plant and the energy station. Unit hot start - heat storage system without surplus condition: At this time, the stored heat in the heat storage system is insufficient. In the initial stage of the unit hot start, the diesel generator supplies power until the unit is rotated and loaded, then the diesel generator is shut down, and the solar thermal collector field of the solar thermal energy is switched to supply the plant electricity of the lithium carbonate processing plant and the energy station. Unit cold start - heat storage system insufficient condition: In the initial stage of the unit cold start after a long cold shutdown, the diesel generator supplies power until the unit is rotated and loaded, then the diesel generator is shut down, and the solar thermal collector field of the solar thermal energy is switched to supply the plant electricity of the lithium carbonate processing plant and the energy station.

[0012] More preferably, the shutdown condition is distinguished according to whether the vacuum is broken after the unit is shut down, including: In normal shutdown conditions of the unit, the vacuum-free shutdown technology is adopted. By accurately controlling the steam inlet and other related parameters of the steam turbine, the unit can be steadily reduced in load until it stops running, while maintaining the vacuum state inside the steam turbine and keeping the necessary equipment running; The unit is shut down to break the vacuum. After the unit is shut down, the vacuum breaking technology is used to break the vacuum environment inside the steam turbine through a specific valve or device to maintain the operation of necessary equipment. In long-term shutdown conditions, based on the vacuum shutdown of the unit, the molten salt system electric heater, molten salt pump and electric heating technology are started to prevent condensation. The molten salt system electric heater converts electrical energy into thermal energy to heat the molten salt to prevent it from solidifying. The molten salt pump maintains the flow of molten salt to ensure uniform heating. The electric heating is wrapped around pipelines and other equipment through the heating tape. After power is turned on, heat is generated to keep the pipelines and equipment warm, preventing the molten salt and related media from solidifying due to long-term shutdown.

[0013] Furthermore, judging whether it is necessary to switch the load condition in advance according to the energy supply capacity of the energy station and the molten salt level further includes: Considering that it takes a certain amount of time for the lithium carbonate processing plant to adjust its operating conditions, the molten salt reserve level is used to determine whether it is necessary to reduce the load in advance during scheduling to ensure that there are sufficient molten salt reserves to safely pass the night. At the same time, if the weather forecast before dawn predicts insufficient daylight during the day, the load should be reduced in advance; If there is sufficient sunlight during the day, the molten salt level can be used to determine that the full-load overnight demand has been met, and the operation will be increased to full load. At the same time, if the molten salt reserves before dawn meet the full-load operation and the weather forecast predicts sufficient sunlight during the day, the operation will be increased to full load.

[0014] On the other hand, a production operation system based on plateau isolated grid is provided, which comprehensively judges and determines the operating conditions of the lithium carbonate processing plant according to the sunshine conditions, the operating conditions of the energy station and the status of the molten salt energy storage system, including: The daytime operation module is used to utilize the sunlight resources during the day, providing electricity through photovoltaics and steam and part of the electricity through solar thermal energy. Low-load operation supports the stability requirements of the isolated grid, and the surplus solar thermal energy is stored in the molten salt energy storage system through electrochemical means; A nighttime operation module, used for providing required electricity and steam through the heat release condition of the molten salt energy storage system at night; The operating condition switching module is used to plan energy storage in advance in combination with weather forecast conditions, and to balance photovoltaic power supply fluctuations and quickly adjust load shedding conditions through the electrochemical energy storage.

[0015] Compared with the prior art, the present invention has the following beneficial effects: Through the combination of photothermal, photovoltaic, and energy storage (electricity storage and heat storage), the present invention enables photovoltaic and photothermal to work together during the day for energy supply, and the photothermal heat storage system takes over at night, while the electrochemical energy storage balances the power supply fluctuations. Regardless of day or night and weather changes, it can ensure stable power supply for the lithium carbonate processing plant, avoid production stagnation caused by interrupted energy supply, and greatly improve the reliability of energy supply; The present invention adopts integrated energy integrated scheduling and operation to achieve island operation, without relying on the external power grid, reducing the impact on the processing plant during external power grid failures or energy supply shortages, and maintaining stable energy supply in an independent environment, enhancing the autonomy and stability of the energy supply system; According to different time periods and the characteristics of the energy system, the present invention provides photovoltaic power supply, photothermal steam supply during the day, and the photothermal unit operates at a low load to maintain the stability of the isolated grid. At night, the photothermal heat storage system releases heat for power supply and steam supply. Each system has a clear division of labor and works in coordination. At the same time, the energy storage system can not only balance the photovoltaic power supply fluctuations, but also store the excess energy when it is generated and release it when the energy is insufficient. In particular, the heat storage system of photothermal can store the excess solar heat during the day for power generation and steam supply at night, achieving efficient cross-time utilization of energy; Both photothermal and photovoltaic in the present invention are clean energies, which do not produce pollutants such as greenhouse gases and sulfides during the production process. Compared with traditional fossil energies, they are environmentally friendly, meet the concept of sustainable development and environmental protection requirements, and contribute to the green production of the lithium carbonate processing plant. Compared with the supply method relying on traditional high-cost fossil energies, this project mainly utilizes free and renewable solar energy, reducing the energy procurement cost; The present invention has detailed and reasonable operation plans and power balance measures for different working conditions such as commissioning, design, black start, shutdown, etc., as well as special weather conditions such as cloudy days and continuous rainy days. Compared with the prior art which has single or insufficient coping means when facing complex working conditions, this project can better adapt to various situations and ensure stable production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings are used to provide further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the drawings: Figure 1 is a flowchart of a production operation method based on a plateau isolated grid according to the present invention; Figure 2 is a typical annual energy supply curve diagram of an energy station in a continuous operation mode according to the present invention; Figure 3 is a typical annual energy supply curve diagram of an energy station in a continuous operation mode after reasonably arranging production according to the present invention; Figure 4 is a typical annual energy supply curve diagram of an energy station in a hierarchical operation mode according to the present invention; Figure 5It is a curve graph of photovoltaic power generation at the design point of the present invention; Figure 6 It is a curve graph of the heat collection of the heat collection field at the design point of the present invention; Figure 7 It is a curve graph of hourly power generation at the design point of the present invention; Figure 8 It is a curve graph of hourly energy consumption at the design point of the present invention; Figure 9 It is a bar graph of the daily heat supply load demand of the present invention; Figure 10 It is a bar graph of the monthly power supply of the photovoltaic part in a typical year of the present invention; Figure 11 It is a bar graph of the monthly power supply of the solar thermal part in a typical year of the present invention; Figure 12 It is a bar graph of the monthly steam supply of the solar thermal part in a typical year of the present invention; Figure 13 It is a curve graph of the annual power supply of the photovoltaic of the present invention; Figure 14 It is a curve graph of the annual power supply of the solar thermal of the present invention; Figure 15 It is a curve graph of the annual steam supply of the solar thermal of the present invention; Figure 16 It is a curve graph of the normal load and the lower limit load under the stable operation of a lithium carbonate processing plant of the present invention; Figure 17 It is a curve graph of the normal load and the lower limit load under the stable operation of an energy station of the present invention; Figure 18 It is a curve graph of the normal load and the lower limit load under the stable operation of an integrated plant of the present invention. Detailed implementation manners

[0017] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0018] This project adopts the technical route of "solar thermal + photovoltaic + energy storage (electricity storage, heat storage)", and operates in an integrated manner of comprehensive energy dispatching to achieve island operation, so as to ensure the safety, stability, continuity and reliability of the production energy supply of the lithium carbonate processing plant.

[0019] The following will describe the specific implementation manners of the present invention in conjunction with the accompanying drawings and embodiments.

[0020] The First Embodiment Please refer to Figure 1 , a production operation method based on a plateau isolated power grid provided in this embodiment, comprehensively judges and determines the operating conditions of a lithium carbonate processing plant according to the sunlight conditions, the operating conditions of the energy station, and the state of the molten salt energy storage system, including: Utilize the sunlight resources during the day to provide electric energy through photovoltaics, provide steam and partial electric energy through solar thermal, operate at a low load to support the stability requirements of the isolated power grid, and store the surplus solar thermal energy electrochemically in the molten salt energy storage system; Provide the required electric energy and steam through the exothermic condition of the molten salt energy storage system at night; Combined with the weather forecast, plan energy storage in advance, and balance the photovoltaic power supply fluctuations and the rapid adjustment of the load shedding condition through the electrochemical energy storage.

[0021] Among them, comprehensively judging and determining the operating conditions of the lithium carbonate processing plant according to the sunlight conditions, the operating conditions of the energy station, and the state of the molten salt energy storage system further includes: The operating modes include a continuous operation mode and a hierarchical operation mode, where In the continuous operation mode, the lithium carbonate processing plant operates continuously at 60% - 100% load, and responds to the load increase / decrease scheduling according to the energy supply capacity of the energy station and the molten salt liquid level.

[0022] Figure 2 The typical annual energy supply curve of the energy station in the continuous operation mode of this embodiment is given, where the yellow line is the 100% load reference line and the red line is the 60% load reference line. It can be seen from the figure that the number of shutdowns throughout the year is 23 times, and the shutdown days are about 50 days. Through operation optimization and reasonable arrangement of production conditions (such as actively reducing the load and increasing the hot salt reserve), the number of shutdowns can be reduced to 11 times. Figure 3 The typical annual energy supply curve of the energy station in the continuous operation mode after reasonable arrangement of production is given. At the same time, the following table gives the energy supply situation of the energy station after reasonable arrangement of production in the continuous operation mode: It can be seen from the above table that under the conditions of the SolarGIS P50 typical annual meteorological data, the equivalent energy supply of the energy station is 7204 hours, the annual operating hours are 8501 hours, the number of shutdowns throughout the year is 11 times, and the shutdown time is greater than 2 hours each time.

[0023] In the hierarchical operation mode, the lithium carbonate processing plant operates under shutdown conditions, 60% load, and 100% load conditions, and judges whether it is necessary to switch the load condition in advance according to the energy supply capacity of the energy station and the molten salt liquid level. In this embodiment, since the lithium carbonate plant has not provided detailed operation characteristic data for the time being, the subsequent analysis is all based on the following assumptions: 1) The switching time for the lithium carbonate plant to increase the load from 60% to 100% operating condition and to decrease the load from 100% to 60% operating condition is 4 hours (subsequently adjusted according to the official data submission of the lithium carbonate plant). 2) The lithium carbonate plant can be quickly started at any time and resume production during a short power outage (within 2 hours).

[0024] Figure 4 The typical annual energy supply curve of the energy station under the hierarchical operation mode is given. The following table presents the analysis of the energy supply situation of the energy station under the hierarchical operation mode: As can be seen from the above table, under the typical annual meteorological data conditions of SolarGIS P50 in this embodiment, the annual equivalent energy supply hours of the energy station are 6,452 hours, and the annual operating hours are 8,135 hours; the energy station shuts down 40 times throughout the year (among which the shutdown times less than 2 hours are 12 times, and the shutdown times greater than 2 hours are 28 times); the photovoltaic curtailment is 13,075 MWh, and the solar thermal curtailment is 172,366 MWh.

[0025] The operating conditions of the energy station in this embodiment are as follows: 1) Daytime photovoltaic power supply + solar thermal steam supply operating condition Utilize the daylight resources during the day. The photovoltaic system provides electrical energy for the lithium carbonate processing plant; the solar thermal system provides steam and part of the electrical energy (the steam turbine operates at the base load). The process flow of the solar thermal part is that the heat transfer oil enters the solar collector field to absorb solar energy heat. After being heated, part of it enters the steam generation system to exchange heat with water to generate steam for continuously driving the steam turbine at the base load. Part of the steam in the lithium carbonate processing plant comes from the steam extraction of the steam turbine, and part comes from the decoupled steam generator. When the light resources are very rich, in addition to generating steam and maintaining the steam turbine at the base load operation, the surplus solar energy of the solar thermal part is stored in the molten salt thermal energy storage system.

[0026] 2) Nighttime solar thermal power supply + solar thermal steam supply operating condition At night, the required electrical energy and steam can be provided through the heat release condition of the thermal energy storage system. Under this condition, the molten salt in the hot molten salt tank is transported to the oil-salt heat exchanger by the hot salt pump to release heat and heat the heat transfer oil. Subsequently, the high-temperature heat transfer oil enters the steam generation system to generate superheated steam to drive the steam turbine to do work and meet the system's power demand; the steam is provided by the steam extraction of the steam turbine.

[0027] 3) Cloudy / continuous rainy day condition On cloudy days, the lithium carbonate processing plant operates at a reduced load; in case of continuous rainy days, the thermal energy storage system can supply the lithium carbonate plant at full load for about 12 hours at most. Combining with the weather forecast, when the rainy days are less than 1 day, it is possible to plan to store as much heat as possible in advance, and ensure that the system does not shut down by reducing the load of the lithium carbonate plant. When the continuous rainy days are more than 1 day, the energy station cannot supply energy externally, and at this time, the lithium carbonate processing plant shuts down.

[0028] 4) Black start condition For black start, a photovoltaic system - electrochemical energy storage system and a diesel generator set are used as power sources.

[0029] In this embodiment, to meet the energy demand of the lithium carbonate processing plant, the photovoltaic power generation at the design point is as Figure 5 shown. At the design point, the theoretical maximum photovoltaic power generation is 233.22 MWh, and according to the user's energy demand, the actual power generation is 221.70 MWh.

[0030] The heat collection situation of the collector field at the design point is as Figure 6 shown. At the design point, the total heat collection of the mirror field is 2569.52 MWht, and there is no waste heat.

[0031] According to statistics, the plant electricity consumption during the day for the solar thermal part is about 9 MW, and at night it is about 4.7 MW; the plant electricity consumption for the photovoltaic part is about 0.12 MW. Combining the power supply situations of photovoltaic, solar thermal, and the power grid, the operation curve graph at the design point can be obtained as Figure 7 and Figure 8 shown. At the design point, the solar thermal power generation is 701.10 MWh, and the power supply is 552.30 MWh; the photovoltaic power generation is 221.70 MWh, and the power supply is 220.50 MWh; the total power generation of photovoltaic and solar thermal is 922.80 MWh, the total plant electricity consumption is 150.00 MWh, and the total power supply of photovoltaic and solar thermal is 772.8 MWh. An appropriately sized molten salt electric heating system can be considered to convert the waste heat of the photovoltaic into heat and store it in the solar thermal molten salt system, thereby improving the utilization rate of the photovoltaic system.

[0032] Therefore, we need to ensure power quality.

[0033] The energy station of the present invention integrates the solar thermal and photovoltaic systems. By configuring the installed capacities of solar thermal and photovoltaic, large - capacity heat storage, and fast - response electrochemical energy storage, the stable supply of electricity and heat energy of the energy station is ensured.

[0034] The configured photovoltaic modules ensure that even in the winter with the worst light resources, they can still serve as the main power source to meet the user's daytime power demand, and the excess electricity is preferentially used to maintain the state of the electrochemical energy storage.

[0035] The configured solar thermal system provides the user's steam demand throughout the day and serves as a power source when the photovoltaic cannot meet the power supply, supplying the user's electricity demand. During the day when the photovoltaic mainly supplies the user's electricity demand, a part of the heat collection of the solar thermal system enters the decoupled steam generator to directly supply the user's steam demand and hot water demand; the solar thermal system uses the heat collection (and / or stored heat) to generate steam, drives the steam turbine to generate electricity at the base load, and at the same time uses the extracted steam to meet the user's heat demand, and the remaining heat is all stored in the molten salt tank.

[0036] Electrochemical energy storage is mainly used to balance the fluctuations of photovoltaic power supply and the rapid regulation of load shedding conditions.

[0037] The configured thermal energy storage system has a capacity sufficient to ensure that users can use energy at full load for 16 hours, and its heat source is a solar thermal system to ensure sufficient heat storage.

[0038] In summary, the capacities of the solar thermal, photovoltaic and thermal energy storage systems in this project have sufficient response capabilities, and the energy security rate has been expanded as much as possible, enabling the energy station of this project to have reliable island operation capabilities.

[0039] The electrical load requirement in this embodiment is 32.2 MW. At the same time, according to the heat load requirements of 35 t / h in the heating season and 31 t / h in the non-heating season, the annual heat supply load requirement can be obtained, as Figure 9 shown, the heat load requirement is higher in winter than in summer.

[0040] In this embodiment, the efficiency of the photovoltaic system is calculated as follows: According to the above, photovoltaic is mainly used to supply the electrical load demand of users. According to the system scheme, 35 MW of photovoltaic is configured, and the annual power generation and power supply are as follows: Among them, the monthly photovoltaic power supply in a typical year is as Figure 10 shown. According to the meteorological conditions and the electricity demand of users, the annual total photovoltaic power supply is about 64529.4 MWhe.

[0041] In addition, the efficiencies of the solar thermal system in this embodiment are as follows: Solar thermal is mainly used for heat supply during the day, while the steam turbine operates at low load; it is used for power supply and steam supply at night. According to the meteorological data conditions, the monthly power supply and steam supply of solar thermal in a typical year can be calculated as Figure 11 and Figure 12 shown. After statistics, the annual power supply of the solar thermal part is about 167600.4 MWhe, and the annual total steam supply heat of solar thermal is about 180584 MWh (equivalent to 237969 tons of steam).

[0042] According to the simulation results, the annual energy supply situation is as Figures 13 to 15 shown. It can be seen that the annual electricity consumption of the lithium carbonate plant after a short shutdown due to insufficient power is about 232 million kWh, equivalent to about 7200 hours of full-load operation. Among them, the photovoltaic curtailment rate is about 6%, and the solar thermal waste heat rate is about 14%.

[0043] The operating conditions of this embodiment include commissioning conditions, design conditions, black start conditions, and shutdown conditions. Among them, the measures for power balance operation under the commissioning conditions include: For the commissioning conditions of the solar thermal power plant, when the light resource is good, during the commissioning period of the solar thermal power plant, the electricity consumption is supplied independently by a 35MW photovoltaic and electrochemical energy storage network. At night, the diesel generator configured by the energy station supplies the night commissioning electricity. For the commissioning conditions of the lithium carbonate processing plant, the plant electricity consumption during the commissioning period of the lithium carbonate processing plant is 32.2MW. During the temporary electricity consumption commissioning conditions, only during the day can the photovoltaic and electrochemical energy storage of the energy station supply the intermittent commissioning electricity of the lithium carbonate processing plant. After the diesel generator set is commissioned, the diesel generator set, the photovoltaic power station, and the electrochemical molten salt energy storage power station are networked as the commissioning power supply for the lithium carbonate processing plant and the energy station.

[0044] The design conditions specifically include: Condition 1, that is, the daytime operating condition. According to the energy consumption requirements of the lithium carbonate processing plant, when the solar radiation energy is sufficient to provide sufficient energy for both the steam generation system and the heat storage system at the same time and the molten salt tank is not full, the energy station is in the photovoltaic or solar thermal power supply, solar thermal steam supply, and heat storage mode. Condition 2. According to the energy consumption requirements of the lithium carbonate processing plant, when the solar radiation energy is not sufficient to provide sufficient energy for both the steam generation system (including the decoupled evaporation system) and the heat storage system at the same time or the molten salt tank is already full, the energy station is in the photovoltaic or solar thermal power supply and solar thermal steam supply mode. At this time, the solar thermal supplies the electricity for the energy station and the lithium carbonate processing plant. This condition often occurs in the morning and evening. Condition 3, that is, the night condition. According to the energy consumption requirements of the lithium carbonate processing plant, when the solar energy resource is insufficient, the thermal energy stored in the molten salt tank can be used for power generation and steam supply. At this time, the solar thermal undertakes the electricity consumption of the energy station and the lithium carbonate processing plant.

[0045] The black start condition is to start the unit when the entire lithium carbonate processing plant loses power. The black start conditions are distinguished according to the unit status and whether there is a surplus in the heat storage system, including: Unit hot start - heat storage system with surplus condition. At this time, there is a certain surplus in the molten salt heat storage system. At the initial stage of the unit hot start (when there is no power supply in the whole plant), the diesel generator supplies power until the unit is rotated and loaded, and then the diesel generator is shut down and switched to the heat storage system of the solar thermal to supply the plant electricity for the lithium carbonate processing plant and the energy station. Unit hot start - heat storage system without surplus condition. At this time, the heat storage capacity of the heat storage system is insufficient. At the initial stage of the unit hot start (when there is no power supply in the whole plant), the diesel generator supplies power until the unit is rotated and loaded, and then the diesel generator is shut down and switched to the solar thermal collector field of the solar thermal to supply the plant electricity for the lithium carbonate processing plant and the energy station. Cold start of the unit - insufficient operating condition of the heat storage system. In the initial stage of cold start of the unit after a long cold shutdown (no power supply in the entire plant), the diesel generator is used to power the unit until the unit is running and carrying the load. The diesel generator is shut down and the solar thermal collector field is used to supply power to the lithium carbonate processing plant and energy station.

[0046] Afterwards, the shutdown conditions are differentiated according to whether the vacuum is destroyed after the unit is shut down, including: In normal shutdown conditions of the unit, the vacuum-free shutdown technology is adopted. By accurately controlling the steam inlet and other related parameters of the steam turbine, the unit can be steadily reduced in load until it stops running, while maintaining the vacuum state inside the steam turbine and keeping the necessary equipment running; The unit is shut down to break the vacuum. After the unit is shut down, the vacuum breaking technology is used to break the vacuum environment inside the steam turbine through a specific valve or device to maintain the operation of necessary equipment. In long-term shutdown conditions, based on the vacuum shutdown of the unit, the molten salt system electric heater, molten salt pump and electric heating technology are started to prevent condensation. The molten salt system electric heater converts electrical energy into thermal energy to heat the molten salt to prevent it from solidifying. The molten salt pump maintains the flow of molten salt to ensure uniform heating. The electric heating is wrapped around pipelines and other equipment through the heating tape. After power is turned on, heat is generated to keep the pipelines and equipment warm, preventing the molten salt and related media from solidifying due to long-term shutdown.

[0047] The power balance under different working conditions is shown in the following table: In addition, considering that it takes a certain amount of time for the lithium carbonate processing plant to adjust its operating conditions, the molten salt reserve level is used to determine whether it is necessary to reduce the load in advance during scheduling to ensure that there are sufficient molten salt reserves to safely pass the night. At the same time, if the weather forecast before dawn predicts insufficient daylight during the day, the load should be reduced in advance; If there is sufficient sunlight during the day, the molten salt level can be used to determine that the full-load overnight demand has been met, and the operation will be increased to full load. At the same time, if the molten salt reserves before dawn meet the full-load operation and the weather forecast predicts sufficient sunlight during the day, the operation will be increased to full load.

[0048] According to the characteristics of the lithium carbonate plant, the time required to run from full load or 60% load to shutdown is analyzed. Based on the weather conditions predicted by the weather forecast and the molten salt reserve level, the shutdown plan is arranged in advance to ensure the safe shutdown of the lithium carbonate plant.

[0049] Specifically, the normal load and lower limit load curves under stable operation of the lithium carbonate processing plant in this embodiment are as follows: Figure 16 The energy requirements are shown in the following table: The normal load and lower limit load curves of the energy station (stable operation) in this embodiment are as followsFigure 17 As shown, the energy requirements are as shown in the following table: In this embodiment, the normal load and lower limit load curves of the integrated plant (stable operation) are as Figure 18 shown, and the energy requirement range is as shown in the following table: Scheduling requirements from the perspective of energy requirements: The energy supply fluctuates within the load demand range (bandwidth).

[0050] This embodiment also provides a production operation system based on a plateau isolated grid, which comprehensively judges and determines the operating conditions of the lithium carbonate processing plant according to the sunshine conditions, the operating status of the energy station, and the status of the molten salt energy storage system, including: A daytime operation module, which is used to utilize the daylight resources during the day, provide electric energy through photovoltaics, provide steam and partial electric energy through solar thermal energy, operate at a low load to support the stability requirements of the isolated grid, and store the surplus solar thermal energy electrochemically in the molten salt energy storage system; A nighttime operation module, which is used to provide the required electric energy and steam through the exothermic condition of the molten salt energy storage system at night; A working condition switching module, which is used to plan energy storage in advance in combination with the weather forecast, and balance the photovoltaic power supply fluctuations and the rapid adjustment of the load shedding condition through the electrochemical energy storage.

[0051] Among them, the functions of each module and unit of the production operation system based on the plateau isolated grid correspond to the steps in the above-mentioned embodiment of the production operation method based on the plateau isolated grid, and their functions and implementation processes will not be elaborated here one by one.

[0052] Finally, it should be noted that the above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's thinking belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements should also be regarded as the protection scope of the present invention.

[0053] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

Claims

1. A production and operation method based on plateau isolated grid, characterized in that: The operating conditions of the lithium carbonate processing plant are comprehensively determined based on the sunshine conditions, the operating conditions of the energy station and the status of the molten salt energy storage system, including: Utilize the sunlight resources during the day, provide electricity through photovoltaics, and provide steam and part of the electricity through solar thermal energy. Low-load operation supports the stability requirements of the isolated grid, and the surplus solar thermal energy is stored in the molten salt energy storage system through electrochemical means. At night, the required electricity and steam are provided through the heat release condition of the molten salt energy storage system; In combination with weather forecast conditions, energy storage is planned in advance, and the electrochemical energy storage is used to balance the fluctuation of photovoltaic power supply and quickly adjust the load shedding condition.

2. The production and operation method based on plateau isolated grid according to claim 1 is characterized in that: The operating conditions of the lithium carbonate processing plant are further determined based on the sunshine conditions, the operating conditions of the energy station and the status of the molten salt energy storage system: The operation modes include continuous operation mode and graded operation mode, among which: In the continuous operation mode, the lithium carbonate processing plant operates continuously at 60% to 100% load, and the load is increased or decreased according to the energy supply capacity of the energy station and the molten salt level response; Under the graded operation mode, the lithium carbonate processing plant operates in shutdown state, 60% load and 100% load conditions, and determines whether the load condition needs to be switched in advance based on the energy supply capacity of the energy station and the molten salt level.

3. The production and operation method based on plateau isolated grid according to claim 1 is characterized in that: Providing electricity through photovoltaics, steam and part of the electricity through solar thermal further includes: By configuring solar thermal and photovoltaic installed capacity, large-capacity heat storage, and fast-response electrochemical energy storage, the photovoltaic system is used as the main power source to meet daytime power demand, and the excess power is prioritized to ensure the maintenance of electrochemical energy storage status; Part of the heat collected by the solar thermal system enters the decoupled steam generator to directly meet the steam demand and hot water demand. The collected heat is used to generate steam to drive the steam turbine to generate electricity at base load. At the same time, the heat demand is met by extracting steam. The remaining heat is stored in the molten salt energy storage system and used for power and steam supply at night.

4. The production and operation method based on plateau isolated grid according to claim 1 is characterized in that: The operating conditions include debugging conditions, design conditions, black start conditions and shutdown conditions, wherein the measures for power balance operation under the debugging conditions include: For the commissioning of the CSP station, when the light resources are good, the 35MW photovoltaic and electrochemical energy storage will independently form a grid to supply electricity for the commissioning of the CSP station. At night, the diesel generators configured in the energy station will supply electricity for the night commissioning. For the commissioning conditions of the lithium carbonate processing plant, temporary power supply can only be supplied by the photovoltaic and electrochemical energy storage of the energy station during the day. After the commissioning of the diesel generator set is completed, the diesel generator set is networked with the photovoltaic power station and the electrochemical molten salt energy storage power station as the commissioning power supply for the lithium carbonate processing plant and the energy station.

5. The production and operation method based on plateau isolated grid according to claim 4 is characterized in that: The design conditions specifically include: Working condition 1: According to the energy demand of the lithium carbonate processing plant, when the solar radiation energy is sufficient to provide sufficient energy for the steam generation system and the heat storage system at the same time and the molten salt tank is not full, the energy station is in photovoltaic or solar thermal power supply, solar thermal steam supply and heat storage mode; Working condition 2: According to the energy demand of the lithium carbonate processing plant, when the solar radiation energy is not enough to provide enough energy for the steam generation system and the heat storage system at the same time or the molten salt tank is full, the energy station is in photovoltaic or solar thermal power supply and solar thermal steam supply mode. At this time, solar thermal power supplies electricity to the energy station and the lithium carbonate processing plant. Working condition three: according to the energy demand of the lithium carbonate processing plant, when solar energy resources are insufficient, the heat energy stored in the molten salt tank can be used to generate electricity and supply steam. At this time, solar thermal energy is used to power the energy station and the lithium carbonate processing plant.

6. The production and operation method based on plateau isolated grid according to claim 4 is characterized in that: The black start condition is to start the unit when the whole lithium carbonate processing plant loses power. The black start condition is distinguished according to the unit status and whether the heat storage system has surplus power, including: The unit is hot started - the heat storage system has a surplus working condition. At this time, the molten salt heat storage system has a certain surplus. The unit is powered by a diesel generator at the initial stage of hot start until the unit is running and carrying load. The diesel generator is shut down and switched to the solar thermal heat storage system to supply power to the lithium carbonate processing plant and energy station; The unit is hot-started - the heat storage system has no surplus working condition. At this time, the heat storage system has insufficient heat storage. The unit is powered by a diesel generator at the initial stage of hot start until the unit is running and carrying load. The diesel generator is shut down and switched to the solar thermal collector field to supply power to the lithium carbonate processing plant and energy station; Cold start of the unit - insufficient heat storage system. In the initial stage of cold start of the unit after a long cold shutdown, the diesel generator is used to power the unit until the unit is running and carrying the load. The diesel generator is shut down and the solar thermal collector field is used to supply power to the lithium carbonate processing plant and energy station.

7. The production and operation method based on plateau isolated grid according to claim 4 is characterized in that: The shutdown conditions are classified according to whether the vacuum is destroyed after the unit is shut down, including: In normal shutdown conditions of the unit, the vacuum-free shutdown technology is adopted. By accurately controlling the steam inlet and other related parameters of the steam turbine, the unit can be steadily reduced in load until it stops running, while maintaining the vacuum state inside the steam turbine and keeping the necessary equipment running; The unit is shut down to break the vacuum. After the unit is shut down, the vacuum breaking technology is used to break the vacuum environment inside the steam turbine through a specific valve or device to maintain the operation of necessary equipment. In long-term shutdown conditions, based on the vacuum shutdown of the unit, the molten salt system electric heater, molten salt pump and electric heating technology are started to prevent condensation. The molten salt system electric heater converts electrical energy into thermal energy to heat the molten salt to prevent it from solidifying. The molten salt pump maintains the flow of molten salt to ensure uniform heating. The electric heating is wrapped around pipelines and other equipment through the heating tape. After power is turned on, heat is generated to keep the pipelines and equipment warm, preventing the molten salt and related media from solidifying due to long-term shutdown.

8. The production and operation method based on plateau isolated grid according to claim 2 is characterized in that: The step of judging whether it is necessary to switch the load condition in advance according to the energy supply capacity of the energy station and the molten salt level further includes: Considering that it takes a certain amount of time for the lithium carbonate processing plant to adjust its operating conditions, the molten salt reserve level is used to determine whether it is necessary to reduce the load in advance during scheduling to ensure that there are sufficient molten salt reserves to safely pass the night. At the same time, if the weather forecast before dawn predicts insufficient daylight during the day, the load should be reduced in advance; If there is sufficient sunlight during the day, the molten salt level can be used to determine that the full-load overnight demand has been met, and the operation will be increased to full load. At the same time, if the molten salt reserves before dawn meet the full-load operation and the weather forecast predicts sufficient sunlight during the day, the operation will be increased to full load.

9. The production and operation method based on plateau isolated grid according to claim 2 is characterized in that: According to the characteristics of the lithium carbonate plant, the time required to run from full load or 60% load to shutdown is analyzed. Based on the weather conditions predicted by the weather forecast and the molten salt reserve level, the shutdown plan is arranged in advance to ensure the safe shutdown of the lithium carbonate plant.

10. A production operation system based on plateau isolated grid, characterized in that: The operating conditions of the lithium carbonate processing plant are comprehensively determined based on the sunshine conditions, the operating conditions of the energy station and the status of the molten salt energy storage system, including: The daytime operation module is used to utilize the sunlight resources during the day, providing electricity through photovoltaics and steam and part of the electricity through solar thermal energy. Low-load operation supports the stability requirements of the isolated grid, and the surplus solar thermal energy is stored in the molten salt energy storage system through electrochemical means; A nighttime operation module, used for providing required electricity and steam through the heat release condition of the molten salt energy storage system at night; The operating condition switching module is used to plan energy storage in advance in combination with weather forecast conditions, and to balance photovoltaic power supply fluctuations and quickly adjust load shedding conditions through the electrochemical energy storage.

Images