With the steady advancement of the national “Double Carbon” plan, the proportion of solar energy generation is continuously increasing. Clean energy generation technologies such as wind power generation and photovoltaic power generation are receiving more and more attention and are widely used in the actual production of electricity. However, wind and photovoltaic power generation technologies have inherent characteristics such as randomness and uncertainty in physical distribution, as well as instability when integrated into the power system on a large scale. As one of the effective means to solve this problem, energy storage technology is becoming increasingly important in engineering practice. This article aims to analyze the application advantages of energy storage technology in solar energy power system, summarize the application methods of energy storage technology in solar energy power generation, illustrate the important role of energy storage technology in building a new power generation system, and derive the general feasibility methods of energy storage technology in the field of solar energy power generation.
1. Overview of Solar Energy Power Generation Development
As the “Double Carbon” plan continues to advance steadily, China’s solar energy clean power generation technologies, such as wind power generation and photovoltaic power generation, have been developing rapidly. According to the current data statistics, by the end of December 2022, the total installed capacity of wind power in China reached 3.6544 × 10^8 kW, with a growth rate of 11.2% . Among them, the newly added installed capacity was 3.763 × 10^7 kW, accounting for 21%. In 2021, China’s wind power generation reached 6.526 × 10^11 kWh, with a year-on-year growth rate of 40.5%. From January to November 2022, the cumulative wind power generation was 6.1448 × 10^11 kWh, with a growth rate of 12.2%.
Wind power generation, as a major component of solar energy power generation system, occupies an important position in the total power generation of China’s power system. In 2021, China’s wind power generation accounted for 8.04% of the national total power generation, and from January to November 2022, wind power generation accounted for about 8.00% of the total power generation. The grid-connected utilization rate of wind power has been stably maintained at a high level. In December 2021, the national wind power utilization rate reached 97.6%. In 18 provinces and cities, including Beijing, Tianjin, Heilongjiang, Shanghai, Jiangsu, Zhejiang, Anhui, Fujian, and Jiangxi, the wind power utilization rate reached 100%. In 2022, the wind power utilization rate reached 96.8%. In 13 provinces and cities, including Beijing, Tianjin, Shanghai, Jiangsu, Zhejiang, Anhui, Guangxi, and Hainan, the wind power utilization rate reached 100%. With the further development of semiconductor materials, the total amount of photovoltaic power generation is also steadily increasing year by year. In 2022, the newly added total capacity of grid-connected photovoltaic power was 8.7408 × 10^11 kW, of which the capacity of centralized photovoltaic power stations was 3.6294 × 10^11 kW, and the total amount of distributed photovoltaic power was 5.1114 × 10^11 kW. By the end of 2022, the cumulative total capacity of grid-connected photovoltaic power was 3.9204 × 10^12 kW, of which the capacity of centralized photovoltaic power stations was 2.3442 × 10^12 kW, and the total amount of distributed photovoltaic power was 1.5762 × 10^12 kW. Currently, the proportion of non-fossil energy in the total energy consumption has increased to about 17.3%, and the proportion of photovoltaic power generation has reached about 4.2%. According to the current statistical data analysis, as the country further increases the investment and layout in wind power, photovoltaic and other new energy power generation technologies, the proportion of new energy power generation will definitely further increase and gradually replace the important role of traditional thermal power generation in people’s livelihood and production development. Therefore, it is imperative to build a new power system.
| Year | Wind Power Installed Capacity (× 10^4 kW) | Newly Added Wind Power Installed Capacity (× 10^4 kW) | Wind Power Generation (× 10^11 kWh) | Wind Power Generation Proportion (%) | Wind Power Utilization Rate (%) |
|---|---|---|---|---|---|
| 2017 | 16367 | 1503 | 3057 | 4.75 | – |
| 2018 | 18426 | 2059 | 3660 | 5.23 | – |
| 2019 | 23005 | 2574 | 4057 | 5.54 | – |
| 2020 | 28153 | – | 4665 | 6.12 | – |
| 2021 | 32848 | 3763 | 6526 | 8.04 | 97.6 |
| 2022 | 36544 | – | 6144.8 | 8.00 | 96.8 |
2. Trends in Solar Energy Development
In order to address the intensifying global climate change and the continuous increase in resource consumption, the development and utilization of solar energy have become a common consensus worldwide. In the past period of time, solar energy technologies have made significant progress. Especially in developed countries such as Europe and the United States, solar energy has become the main energy source, and its proportion in the energy structure is increasing.
Currently, China is also increasing its emphasis on solar energy, starting to introduce solar energy power generation into the power grid, continuously vigorously developing solar energy technologies, and focusing on building solar energy power system to alleviate the current tight electricity supply situation. The country has successively issued a series of policies, such as the “Opinions on Improving the System and Policy Measures for the Green and Low-Carbon Transformation of Energy” and the “14th Five-Year Plan for Renewable Energy Development” and the “14th Five-Year Plan for Modern Energy System,” encouraging enterprises to transition to clean energy and move towards industrial upgrading. Due to the fact that the supply side of traditional fossil energy cannot currently meet the increasing energy demand in the country, and wind power generation is one of the most mature technologies, has the most significant scale development conditions, and the most commercial development prospects in the field of renewable energy, vigorously developing wind power generation is of great strategic significance for China to promote the optimization of its energy structure.
Currently, local governments with natural geographical resources such as wind energy are actively planning and deploying clean energy construction, actively promoting the development and utilization of solar energy such as wind power, and boosting economic development. As of 2022, the newly added installed capacity of wind power and photovoltaic power generation in the country exceeded 1.2 × 10^8 kW, breaking through 1 × 10^8 kW for three consecutive years. The wind power and photovoltaic power generation for the first time exceeded 1 × 10^12 kWh, reaching 1.19 × 10^12 kWh, with a year-on-year growth of 21%.
The development of solar energy is an important direction in the future, not only with broad market application prospects but also conducive to the completion of industrial upgrading and energy structure optimization reform by China’s energy enterprises.
3.Application Status of Energy Storage Technology in the Solar Energy Power System
3.1 The Role of Energy Storage Technology in the Field of Solar Energy Power Generation
Energy storage technology realizes the release and storage of energy through artificial means. It addresses the randomness and volatility of solar energy power generation, thereby effectively reducing the impact of distributed power sources on the power grid. With the continuous decrease in the construction cost of energy storage equipment, the status of solar energy industry in the power system is gradually improving.
Energy storage equipment can serve as both an energy buffer and a backup power source, playing a certain role in improving the inconsistency problem of power transmission and transformation, effectively improving the safety and stability of the power grid and enhancing the dispatchability of the power system. Energy storage equipment effectively suppresses the grid-connected power fluctuations of renewable energy, reduces the impact on the power grid, improves the economy of the power grid, and reduces unnecessary energy consumption.
3.2 The Importance of Energy Storage Technology for the Development of Solar Energy Power System
3.2.1 Creating Conditions for the Large-Scale Use of Solar Energy Power Generation
Wind power generation technology and solar power generation technology are important components of the current solar energy power generation system. Solar energy has advantages that traditional fossil energy does not have, such as cleanliness and recyclability, but it also has the characteristics of volatility and intermittency, which affect the safe and stable operation of the power grid. The application of energy storage technology can effectively improve the stability problem of solar energy when it is connected to the grid.
3.2.2 Changing the Energy Supply Structure
As energy demand gradually increases, the sole use of traditional fossil energy is not conducive to the sustainable development of China’s economy and will cause a serious environmental crisis. To ensure sufficient energy supply, the current energy supply structure must be changed. In the process of using solar energy, combined with the actual energy demand of users, a suitable method is adopted to scientifically design the solar energy system, and by reasonably using energy storage technology (independent or grid-connected), energy supply is guaranteed, and the environment is protected.
3.2.3 Peak Shaving and Stable Output Control
The intermittent and fluctuating characteristics of solar energy power signals, such as wind power and photovoltaic power generation, are the main reasons why solar energy cannot be used on a large scale in the power grid. The use of energy storage technology is an effective means to solve this problem. By using energy storage equipment to peak-shave the power station and ensure its stable output in the later stage, without increasing the capacity of the power grid, and improving the utilization rate of solar energy.
3.2.4 Enhancing System Stability and Operational Efficiency
The stable operation of the power system is an important indicator to ensure the safety of the power grid. During the operation process, any failure in any part will have an adverse impact on the safety and stability of the entire system. The use of an energy storage system can ensure effective control of the power grid system in the event of a fault, effectively suppress the fluctuations in the power grid system, and achieve self-regulation of the power grid system through mutual coordination. When the power grid system is out of power or blackout, the energy storage equipment can provide effective power supply for a period of time.
3.3 Application Advantages of Energy Storage Technology in the Field of Solar Energy Power Generation
3.3.1 Suppressing the Power of Wind Power Grid Connection
The process of solar energy grid connection has a negative impact on the power system, which damages the voltage stability. By combining energy storage technology, modeling and analyzing the wind power farm, constructing an effective wind-photovoltaic-storage coordinated control scheme, and carrying out the regulation and capacity configuration of reactive power and active power in the grid, the frequent changes in power can be controlled, and the output power of the grid connection can be stabilized.
3.3.2 Stabilizing the Frequency of the Power System
The process of solar energy grid connection has a negative impact on the power system – frequency fluctuation. In the case of solar energy power generation, by adding an effective energy storage system, power compensation can be carried out on the power system to ensure the consistency of the grid-connected frequency. On this basis, the optimization of the energy storage system can improve the lifespan of the solar energy power generation system, thereby reducing the production cost of the entire power system. By adding an energy storage system in the solar energy grid connection and using the energy storage system as a backup power source, the phenomenon of power supply interruption caused by power generation intermittence can be improved, and the power supply stability can be improved.
3.3.3 Optimizing the Power Quality of the Power System
During the process of solar energy power generation grid connection, problems such as voltage drop or flicker may occur, leading to a decrease in power quality. By adding energy storage equipment to the solar energy system, the power fluctuation can be controlled smoothly, and the power quality can be optimized. By adding energy storage devices such as supercapacitors to solar energy grid connection and using fuzzy logic control to regulate the power quality, the problem of power quality degradation can be further improved.
3.3.4 Improving the Economy of Solar Energy Grid Connection
Due to the variable output power of solar energy, in order to improve the stability of the power system, the standby capacity needs to be increased. In the process of solar energy grid connection, by using physical energy storage methods such as pumped storage, electrical energy can be converted into stable physical potential energy, improving the stability of the grid-connected operation of the wind farm. By combining the goal of maximizing electricity price revenue and the goal of minimizing the output power of solar energy, two corresponding solar energy power generation and physical energy storage schemes are formed to achieve corresponding stable regulation, which can not only improve the operational stability of the power system but also effectively reduce the cost input of wind power generation.
3.4 Energy Storage Forms in the Field of Solar Energy Power Generation
At present, for the application of energy storage technology adopted when large-scale solar energy power generation is integrated into the power system at home and abroad, the main approach is to combine energy storage and functional energy storage. The main application forms of energy storage technology in solar energy field are shown in Figure 6. Energy storage forms such as pumped storage, lithium batteries, and flow batteries are suitable for frequency modulation and peak shaving. Power storage forms such as flywheel energy storage, supercapacitor energy storage, and superconducting magnetic energy storage are suitable for real-time load smoothing and optimizing power quality.
| Energy Storage Technology | Examples | Application Scenarios |
|---|---|---|
| Chemical Energy Storage | Lead-Acid Batteries, Lithium Batteries, Flow Storage Batteries, Metal-Air Energy Storage, Hydrogen Energy Storage | Frequency Modulation, Peak Shaving |
| Physical Energy Storage | Pumped Storage, Flywheel Energy Storage, Compressed Air Energy Storage, Phase Change Energy Storage, Superconducting Magnetic Energy Storage | Load Smoothing, Power Quality Optimization |
3.5 Application Forms of Energy Storage Technology in the Field of Solar Energy Power Generation
Energy storage technology, as one of the key core technologies in building solar energy power system, is distributed in all links of power generation, distribution, and consumption. Due to the different application situations in the power system, the value brought by energy storage technology to the power grid is also different. However, in engineering practice, energy storage equipment is mainly distributed on the solar energy side, the traditional power source side, the power grid side, and the user side.
3.5.1 Solar Energy Side
The output power of solar energy is uncertain and volatile, which increases the difficulty of grid connection. The energy storage system utilizes its own energy spatio-temporal translation characteristics to improve the controllability of the output power of wind power and enhance the grid-connected access capability of solar energy. Both wind power generation and photovoltaic power generation are affected by environmental and weather factors. By utilizing the complementary characteristics of wind and light resources and configuring an appropriate capacity of energy storage devices in the system, the fluctuations caused by the grid connection of wind and light can be stabilized, the impact on the power grid can be reduced, and the acceptance capacity of the power grid for solar energy can be improved.
3.5.2 Traditional Power Source Side
The traditional power source mainly refers to thermal power, which will undertake the frequency modulation task or be used as a backup power source in the future solar energy power system. According to the “Power Quality – Deviation of Power System Frequency” (GB/T 15945 – 2008), the limit of frequency deviation under normal operating conditions is ± 0.2 Hz. Thermal power has disadvantages such as low climbing rate and slow regulation speed during the frequency modulation process. The energy storage system has the ability of rapid response and bidirectional regulation. By configuring a battery energy storage system on the side of the thermal power unit to assist the thermal power unit in frequency modulation, the safe and stable operation of the power grid can be ensured, and the service life of the thermal power unit can be extended.
3.5.3 Power Grid Side
The access of energy storage power stations can effectively improve the peak shaving ability of the power grid, alleviate the power supply pressure during peak loads, achieve peak shaving and valley filling, smooth the load fluctuations in the distribution network, ensure the safe and stable operation of the system, and improve the voltage quality of the power grid. Due to the flexibility and rapid response characteristics of the reactive power compensator, when the violent fluctuation of active power in the power grid threatens the frequency stability of the power grid, the auxiliary frequency modulation of the energy storage power station can maintain the frequency stability of the power grid and improve the absorption capacity of the power grid side system for solar energy. Due to the large-scale access of distributed solar energy to the power grid, the power grid side covers more microgrids and active distribution networks. The volatility of renewable energy such as wind and light in the microgrid has a negative impact on the power system. The addition of the energy storage system can not only maintain the energy balance of the microgrid system but also effectively alleviate the problems of abandoned wind and abandoned light. The active distribution network is composed of distributed power sources such as wind and light, controllable loads, and distributed energy storage, which can actively participate in operation, control, and management, thereby improving the acceptance capacity of the distribution network for distributed solar energy. The energy storage system also plays a key role in the active distribution network.
3.5.4 User Side
The energy storage device allows users to independently or through external dispatching control to store or release electrical energy. By taking advantage of the time-of-use electricity price policy, users can charge and discharge at different times to make profits and reduce their electricity costs. When the power load is at a peak and the electricity price is higher, users can discharge the energy storage device to meet their own electricity demand. When the power load is at a low trough and the electricity price is lower, users can store electrical energy through the energy storage device, achieving peak shaving and valley filling, reducing the pressure on the power grid during peak loads, and lowering their electricity costs. When users participate in the demand-side response and regulate the power grid, the access of the energy storage system can enhance the user’s ability to participate in the demand-side response. In cases where the user has self-generation and surplus electricity for grid connection but may experience insufficient power, the energy storage device can serve as an uninterrupted power source, improving the reliability of power supply. When the power generation device is at its peak output, the energy storage device can store the electrical energy. When the power grid is at a peak load and the electricity price is higher, the energy storage device can discharge, allowing the user to meet their own electricity demand while using the surplus electricity for grid connection and earning revenue.
4. Application Methods of Energy Storage Technology in the Field of Solar Energy Power Generation
The above content discusses the application scenarios of energy storage equipment in the power system and analyzes the unique advantages of energy storage technology in stabilizing the grid connection of solar energy power generation. So, how can energy storage technology be applied to the generation side of solar energy to leverage its particular advantages? Based on the actual engineering situation on the generation side, there are generally three ways to achieve this:
4.1 Method One
When a frequency deviation occurs, by utilizing the frequency modulation principle of the synchronous generator and combining the governor and the deviation rate, the power output of the generator set can be changed quickly to complete the primary frequency modulation. Subsequently, the secondary frequency modulation is carried out. By using solar energy storage device with a power electronic converter, the response of frequency modulation can be controlled within milliseconds, ensuring that the electrical signal frequency is stabilized at the standard value and achieving a good frequency modulation effect.
4.2 Method Two
The generator set is combined with the energy storage device to simulate a virtual synchronous generator set. This allows the traditional synchronous frequency modulation model to be transferred through the virtual frequency modulation model platform. By adding an energy control system to the energy storage system and enabling the virtual model algorithm to run, the energy storage system can achieve peak shaving and frequency modulation for the solar energy grid connection.
4.3 Method Three
Peak shaving and frequency modulation can be achieved through the unified control and dispatching of the power grid. The energy storage system completes the corresponding instructions under the command of the dispatching, and by combining the active and reactive power values of the dispatching, the power output or absorption of the power grid can be adjusted and controlled. Since the algorithm for single peak shaving and frequency modulation is relatively complex, the assistance of the power grid can further reduce the difficulty of regulation and control.
5.Conclusion
In this article, the author introduces the development trends of solar energy in recent years and the application forms of energy storage technology in the solar energy power system. By analyzing the role of energy storage technology in the solar energy power system, some general feasible methods for the application of energy storage technology in the field of new energy power generation are derived.
With China’s vigorous development of clean energy technologies such as wind power and photovoltaic power, and the steady progress towards the goals of “carbon peaking” and “carbon neutrality”, focusing on building a new power system dominated by clean energy, energy storage technology, as a key technology for the grid connection of solar energy power generation, will certainly usher in a broad application scenario.