Source: cosinsolar.com
From August 6, 2021 (after the completion of the steam turbine rectification ) to August 5, 2022, the total annual cumulative actual power generation of the SUPCON SOLAR Delingha 50MW Molten Salt Tower CSP Plant was 158GWh, reaching 108% of the designed annual power generation (146GWh), setting the highest operational record of the tower CSP plant in the world.
Power plant power generation data for the last 12 months (including: no power generation from August 1 to 5, 2021 due to rectification, and cumulative power generation from August 1 to 5, 2022 is 2,782,400 kWh).
After the designed annual power generation was completed one month ahead of schedule on 5th of last month, the plant continued to operate in good condition. Although the local weather was not good in the past month, there were several days of continuous overcast with rain and sandstorm, among which 7 overcast and rainy days it was not possible to collect solar energy, and the sandstorm affected the power generation of about 1.5GWh. However, it still achieved the complete annual cumulative power generation of 158GWh, and became the first Molten Salt Tower CSP Plant in the world whose annual actual power generation exceeded the annual designed power generation.
The system of CSP plant is complex, and the factors that affect its production include system design, system performance, equipment reliability, operation optimization and so on. It is easy for the CSP plant to generate electricity but not simple to achieve production target. Here are the reasons for the success of SUPCON SOLAR Delingha 50MW Molten Salt Tower CSP Plant.
01 The optimal matching of each system improves the overall operating efficiency
The matching between the Solar Block, TESS and SGS Block, and turbine and generator system is the prerequisite to determine the performance of the CSP Plant. In order to improve the efficiency of each system and reduce the investment cost, multiple factors should be considered in the design of CSP station. The Molten Salt Tower CSP Design Software independently developed by Cosin Solar can achieve the optimal matching of each system through big data calculation and repeated iteration according to different boundary conditions.
02 High efficiency of the Solar Block to ensure thermal energy collection and power generation
The performance (efficiency) of the Solar Block is the basis of determining the performance of a CSP Plant. In Solar Block, the concentration precision of the heliostat directly affects the sub-system efficiency, and thus affects the efficiency and power generation of the plant. By applying self-developed High-precision Intelligent Heliostat, High-efficiency Calibrating System, HFCS, etc., and optimizing the layout method of solar field and the structure and process design of receiver, Cosin Solar greatly improves the efficiency of Solar Block.
1. Optimization for solar field design
The special solar field design software of Cosin Solar is the basis of high efficiency of the whole solar field.
Ø Optimization principle: View the solar field from the perspective of the receiver– no occlusion
Ø The solar field efficiency is about 1.5% higher than that of the conventional radiation layout
Ø The land utilization is about 2.5% higher than that of the traditional radiation layout
2. High-precision Intelligent Heliostat
The high-precision intelligent heliostat independently developed by Cosin Solar has high profile accuracy and tracking accuracy, which can accurately reflect the sunlight to the designated position of the receiver, improve the facula quality, reduce the energy spillover on the receiver, effectively improve the solar-electric conversion efficiency, so as to improve the power generation of the CSP Plant.
3. High-efficiency Calibrating System
The regular calibration of the solar field is very important to ensure the precision of concentration. The automatic calibration based on machine vision methodology is adopted, which is 25 times more efficient than the traditional whiteboard calibration, and can realize automatic cyclic calibration without the need for operators to be on duty.
Ø During the construction period of the plant, due to the deviation of the heliostat installation, the full-field heliostat needs to be calibrated once before being put into operation. By adopting the correction system of Cosin Solar, the calibration time of the solar field can be greatly reduced, thus shortens the delivery time. At the same time, the installation cost can be greatly reduced because the heliostats installation process does not require accurate positioning and measurement of deviation.
Ø After the plant is put into operation, the heliostat accuracy will change due to the change of the settlement of the heliostat foundation and the influence of the external environment such as wind speed and temperature. The calibration system of Cosin Solar can carry out high frequency periodic calibration on the operating mirror field, ensuring that during the whole life cycle, the full-field heliostat is always at the best accuracy level.
4. Highly Integrated Control Systems
Relying on the accumulation of nearly 30 years in the control system, the HFCS independently developed by Cosin Solar can realize the cluster control of large-scale solar field, and greatly improve the utilization of solar resources while ensuring the safe and stable operation of the solar and thermal gathering system of the plant, thus improving the power generation level of the plant.
Ø The software and hardware of the control system are completely independently developed. The HFCS, the receiver control system and the DCS of the whole plant are deeply coupled and interlinked, realizing the automatic control of the main operation process.
Ø Transplant the mature concept of DCS control system, control system server, power supply, network multiple redundancy;
Ø Powerful control system ensures accurate sun tracking throughout the field, reduces the overflow of facula, and ensures evenly distributed energy on the surface of the receiver.
5. High efficiency and high safety receiver
Molten salt receiver, which uses molten salt as working medium, is faced with severe conditions such as high temperature, frequent drastic changes between high and low temperature, corrosive environment and so on. In order to ensure the safe and efficient operation of the molten salt receiver, Cosin Solar has been optimizing from many aspects.
*Material selection: imported high nickel alloy tube, resistant to high temperature, corrosion, thermal stress, thermal fatigue; High absorption coating, improve the absorption rate of solar resources
*Structure design: flexible structure, thermal stress, thermal fatigue; Modular factory prefabrication, avoid on-site processing, ensure the performance of the receiver, improve installation efficiency
*Control System: ensure that the surface temperature of the receiver is uniform, the receiver control system and the HFCS are deeply coupled, interlock control, and reduce the thermal shock
*Anti-frozenand anti-blocking: optimize the internal pipeline structure to reduce the occurrence of frozen and blocking conditions; The surface energy of the receiver can be monitored in real time, and the surface temperature can be monitored at any time. The automatic salt control system makes use of the solar field energy to speed salt melting and dredging up under frozen and blocking conditions
—— ★ —— ★ —— ★ —— ★ —— The comprehensive advantages of the Solar Block of Cosin Solar—— ★ —— ★ —— ★ —— ★ ——
ü High-precision Intelligent Heliostat + Efficient automatic Calibrating System + Highly integrated HFCS ensures the concentration accuracy of the whole solar field in the whole life cycle
ü High precision concentration of heliostat and high efficiency receiver bring high efficiency of the whole Solar Block
ü High efficiency Solar Block system, provide guarantee for the plant thermal collection and power generation
Cosin Solar’s capbility and performance in the Solar Block obtains the recognition of the industry, leading the IEC standards of the CSP plant heliostats field control system, and two national standard “Technical requirements of thermal receiveing system of CSP tower plant” and “Specifications of the heliostats for CSP tower plant”.
03 Reliable molten salt storage and thermal exchange system ensures high quality power generation
Cosin Solar has deeply studied the characteristics of molten salt system, and the independently developed process package optimization technology of molten salt thermal storage and exchange system has greatly improved the reliability and availability of special equipment.
1. The unique structure design of molten salt storage tank can improve the capacity and reduce the thermal energy loss at the same time. The design of equalizing the flow in the tank greatly improves the reliability of the tank body.
2. The molten salt thermal exchanger uses the world’s first double array design scheme, and with a lot of optimization, greatly improve the availability of equipment; At the same time, it can also realize a large range and fast load change, and realize better load adjustment and speed than the traditional ones in thermal power;
3. Joint design of molten salt pump, pipeline and supporting platform, overcome technical challenges such as wear resistance design of molten salt pump in high temperature environment and seal design of molten salt valve, etc.
04 The core equipment is controllable and reliable to ensure the stable operation of the plant
The reliability of key equipment is an important factor affecting the operation performance of CSP Plant.
1. The design and manufacture of core equipment of the Solar Block are autonomous and controllable
Ø The core equipment such as heliostats, welding parts, sheet metal parts and electronic control parts are all equipped with automatic production equipment and special tooling to ensure the consistency of the quality of the production and manufacturing process.
Ø Automatic heliostat assembly line, PLC human-computer interaction control, workpiece automatic feeding, automatic positioning, automatic inter-process flow, online detection, avoid the outflow of unqualified products.
2. Equipment integration optimization of molten salt heat storage and exchange system
Ø We cooperate closely with equipment manufacturers, deeply participate in the equipment design, manufacturing and installation process, master the key performance and control points of equipment, form a complete equipment quality control process of molten salt storage and thermal exchange system, and ensure the operation reliability of key equipment.
3. The reliability of its core equipment has been verified
Ø Most applications in China: three tower CSP Plant, the longest of which has been in use for nearly 10 years
Ø High altitude (above 3,000 meters), extreme cold (as low as -37 ° C), and blowing sand
05 Fully automatic operation system to achieve the best operation strategy
The core of operation optimization of plant is to maximize the utilization of solar resources under the safe and stable operation of the receiver.
1. Key issues:
Cloud is an important factor affecting the thermal energy collection and power generation of Plant. For example, there are more than 200 cloudy days in Delingha a year. How to select the operation strategy in the case of cloud?
Continued operation: It may cause uneven surface temperature of the receiver, affecting safe operation.
Shutdown and salt drainage: The “safest” option for operators, but it wastes solar resources and requires preheating of the receiver and pipes to restart after a cloud.
2. The solution:
*Cloud Forecasting System: Through cloud identification and cloud motion tracking, DNI prediction function within 30 minutes is realized to help operators select the best operation strategy.
*The heliostats field energy scheduling system: Through the unified field energy scheduling across the whole area, the surface energy of the receiver can be evenly distributed under cloud conditions, without drastic changes in surface temperature, and the field shutting down and salt drainage can be avoided as far as possible, so as to achieve the maximum utilization of solar resources.
1）Fully automatic operation of the Solar Block system：
In order to improve the stability and security of the system operation, the automatic operation software independently developed by Cosin Solar realizes the automatic control of the Solar Block system and one-click start and stop, which reduces the system efficiency degradation and equipment operation risk caused by human factors.
Ø Meteorological system, cloud monitoring system, infrared system and HFCS are deeply coupled, realizing automatic operation strategies under complex conditions such as cloud.
Ø Abnormal condition automation: automatic detection and troubleshooting of receiver blockage, overtemperature safety protection, power-off safety interlock, etc.
2）Cloud Forecasting System:
The first Cloud Forecasting System developed in China has the functions of cloud identification and motion tracking, and realizes the DNI prediction function within 30 minutes.
3）The simulation platform of the Solar Block
Operation simulation
Ø Simulation of key equipment, such as receiver and heliostat field, supports the simulation of temperature distribution data on the surface of the receiver
Ø Simulation of the whole process of system preheating, heating, running, and stopl
Ø Operation data export function
Training
Ø Consistent with the actually software platform of the project to improve the effect of operation training
Ø Interactive cooperation between teacher and student station, to achieve online assessment function
Fault simulation
Ø Operation simulation and interlocking protection after failure
Ø To help operators to formulate fault handling plans to shorten the troubleshooting time
4）Heliostat Field Auto-cleaning Vehicle
It is very important for the CSP Plant to maintain the cleanliness of the heliostat. The fully automatic driverless cleaning vehicle of Cosin Solar has the functions of automatic navigation, water washing/dry cleaning, which can greatly improve the cleaning efficiency of the heliostat field, ensure the cleanliness of the mirror and reduce the operation cost.
*Summary*：
According to the different operation performance of the same type of CSP Plants around the world, the characteristics of CSP Plants could be recognized as”easy to build and difficult to achieve production”. For a CSP Plants with an investment of billions of RMB, whether it can reach the designed power generation on schedule is the premise that determines whether the project owner can get the expected profit. Therefore, when selecting the key technology sources and core equipment of the CSP Plants, the operation performance of the previous performance should also be the primary factor considered by the owner.
The story behind the successful operation of SUPCON SOLAR Delingha 50MW Molten Salt Tower CSP Plant is many years’ dedicated research and development and engineering practice of Cosin Solar in the field of tower CSP, which is our long-term investment and accumulation in design optimization, system performance, equipment reliability, operation strategy and other aspects. It fully proves the advanced, mature and reliable nature of our independent research and development tower CSP technology.
SUPCON Delingha 50MW Tower CSP Project：
SUPCON SOLAR Delingha 50MW Molten Salt Tower CSP Plant, one of China’s CSP demonstration projects. The power plant has 50MW of installed capacity with 7-hour molten salt storage system. The solar field consists of 27135 sets of 20㎡ heliostat, and designed to generate 146GWh electricity annually, and can save 46,000 tons’ standard coal, and reduce 121,000 tons’ CO2 emission, bringing enormous benefits to the economy and society. The plant is designed and constructed based on Cosin Solar’s fully patented technologies, and over 95% equipment are domestically sourced. The plant passed complete technical assessment of Fichtner, a German independent engineering consulting company with remark of “The design of the plant corresponds to state-of-the-art design known by Fichtner”.