With the global emphasis on environmental protection and energy transition, the development and utilization of renewable energy have attracted increasing attention. Among them, wind and solar photovoltaic (PV) power generation, due to their clean and renewable characteristics, have become important forces driving the optimization of energy structures. However, because wind and solar energy are natural resources, their power generation processes exhibit significant volatility, posing great challenges to the stable operation of the power grid. To address these issues, battery energy storage systems (BESS) are widely applied in wind-PV systems. By storing and releasing electrical energy, they can achieve energy balance and optimize configuration. Based on this, this paper aims to explore the battery energy storage technology in wind-PV systems under the low-carbon concept, providing technical support for the efficient utilization of renewable energy and the low-carbon transition of energy.
1. Analysis of Battery Energy Storage Technology
1.1 Comparison of Different Types of Batteries
As a core component of modern energy storage, battery energy storage technology encompasses various battery types, each playing an indispensable role in different application scenarios due to its unique performance. Table 1 compares the advantages and disadvantages of different battery types.
| Battery Type | Advantages | Disadvantages |
|---|---|---|
| Lithium-ion Battery | High energy density, long cycle life, lightweight | High cost, safety issues |
| Lead-acid Battery | Low cost, high reliability, high temperature resistance | Large volume and weight, low energy density |
| Sodium-sulfur Battery | High energy density, long life, environmentally friendly | High temperature operation requirement, safety concerns |
Among these, lithium-ion batteries have high energy density, storing more electrical energy under equal conditions, thus providing longer power support for equipment. Moreover, their long cycle life allows them to withstand numerous charge-discharge cycles without performance degradation, which is especially important for devices requiring frequent use or long-term operation. In contrast, although lead-acid batteries are slightly inferior in some performance indicators, their manufacturing and maintenance costs are low, making them irreplaceable in many fields. As a mature and well-established technology, lead-acid batteries are widely recognized for their reliability and stability, playing a vital role in applications such as power supply backup and emergency power sources that demand high reliability. Sodium-sulfur batteries, with their high energy density and long lifespan, can maintain stable performance output over extended periods, providing reliable power support for large-scale energy storage systems. More importantly, sodium-sulfur batteries use environmentally friendly materials, have minimal environmental impact, and align with the current global advocacy for green and low-carbon development. Therefore, they have broad application prospects in large-scale energy storage systems, smart grids, and other fields.
1.2 Composition and Working Principle of Battery Energy Storage System
A battery energy storage system mainly consists of a battery pack, a battery management system (BMS), an energy converter, and a control system. These components work together to ensure efficient, safe, and stable operation. The battery pack is the core component, responsible for storing and releasing electrical energy, providing continuous energy support for the entire system. It is typically composed of multiple battery cells connected in series or parallel to achieve the required energy storage capacity. Each cell has unique voltage and capacity characteristics, which collectively form a complex performance map of the battery pack. The total voltage and current of the battery pack are influenced by the connection method among cells. Therefore, when the BMS is integrated inside the battery pack, it enables comprehensive data collection and monitoring of the entire pack. Through a high-precision sensor network, the BMS can capture key parameters such as voltage, current, and temperature in real time, providing important data for understanding the working status of the battery pack. Based on these meticulously collected and analyzed data, the BMS ensures that the battery pack operates within strictly controlled safe ranges, effectively preventing potential hazards such as overcharging, overdischarging, and overheating, thereby ensuring the excellent performance and long-term stability of the entire system. However, the functionality of the BMS extends far beyond basic safety protection. It also possesses excellent voltage balancing capability, allowing it to sense and automatically adjust subtle voltage differences among individual cells, ensuring that the battery pack as a whole performs optimally and preventing premature aging of any cell due to voltage imbalance. Additionally, the BMS protects the battery pack from external interference and potential damage, such as sudden short circuits, open circuits, or abnormal charging/discharging behavior, responding within milliseconds to build an impregnable safety barrier for the battery pack. Furthermore, the BMS has intelligent thermal management functionality. According to real-time battery pack temperature, it intelligently adjusts cooling or heating systems to ensure the battery pack always works within the most ideal temperature range, further extending battery life and improving overall system performance. The BMS also has intelligent performance analysis capabilities, deeply mining and analyzing usage data to provide accurate scientific basis for optimal scheduling of the system. This not only helps improve the overall efficiency of the battery energy storage system but also enhances its reliability and stability. The working principle of the battery energy storage system is illustrated in the figure below, which is inserted at an appropriate position in the article.
The energy converter (such as a bidirectional inverter) converts DC power from the battery pack to AC power for grid connection, or vice versa during charging. The control system coordinates all components based on real-time data from the BMS and grid conditions.
Mathematically, the state of charge (SOC) of a battery pack can be expressed as:
$$
SOC(t) = SOC(0) + \frac{1}{C_{rated}} \int_{0}^{t} \eta_{c} P_{c}(\tau) d\tau – \frac{1}{C_{rated}} \int_{0}^{t} \frac{P_{d}(\tau)}{\eta_{d}} d\tau
$$
where \( C_{rated} \) is the rated capacity, \( \eta_{c} \) and \( \eta_{d} \) are charging and discharging efficiencies respectively, and \( P_{c} \) and \( P_{d} \) are charging and discharging power.
1.3 Advantages and Challenges of Battery Energy Storage Technology
Battery energy storage technology plays an important role in energy management, effectively alleviating the mismatch between power supply and demand. By collecting excess electricity during low demand periods or peak renewable generation hours, and releasing it during peak demand, it ensures power supply stability. This technology not only improves energy utilization efficiency but also provides a feasible solution for balancing power supply and demand. In promoting the integration of renewable energy into the grid, facing the intermittency and instability of clean energy sources like solar and wind, battery energy storage can balance power output: storing excess electricity when generation exceeds demand, and supplementing when generation falls short, thus maintaining grid continuity and reliability. This regulation mechanism significantly enhances the grid-connection capability of renewable energy and promotes the widespread application of clean energy. From the grid operation perspective, battery energy storage systems have the advantage of rapid response, capable of completing charge/discharge cycles within milliseconds, helping to adjust grid frequency and stabilize voltage fluctuations in real time, greatly improving power quality. This dynamic regulation function is crucial for maintaining grid safety and stability, especially during sudden load changes.
However, the development of battery energy storage technology still faces many challenges. First, in terms of cost, it is necessary to reduce expenses through material innovation, process optimization, and large-scale production. Second, in terms of performance improvement, key indicators such as energy density and capacity need to be enhanced. Third, extending battery cycle life and improving system reliability are also urgent issues, requiring continuous improvement of material systems and system design. Finally, for large-scale energy storage applications, intelligent management systems need to be developed, using advanced control algorithms and monitoring techniques to achieve efficient management and monitoring of battery energy storage systems, ensuring safe and stable operation and maximizing their effectiveness.
2. Application of Battery Energy Storage System in Wind and Solar PV Systems under Low-Carbon Concept
2.1 Application of Battery Energy Storage System in Wind Farms
In the context of actively practicing green and low-carbon environmental protection concepts, wind farm construction is gradually becoming a key force driving global energy transformation and sustainable development. In this process, cleverly integrating battery energy storage systems into wind farms has opened new avenues for efficient utilization of wind energy and improved grid stability. Wind energy is a clean and renewable natural resource. Although it contains huge energy potential, its power generation process inevitably involves significant fluctuations, mainly due to wind speed variations, which cause corresponding fluctuations in the output power of wind turbines. Such unstable power output is detrimental to the stable operation of the grid. To effectively address this challenge, engineers have continuously studied and finally connected advanced battery energy storage systems closely with wind turbines, achieving efficient use of wind energy and effective storage of electrical energy. This combination not only enables real-time conversion of wind energy into electricity but also safely and efficiently stores excess electricity in the battery bank. When wind speeds are strong and wind turbines are operating at full capacity, the generated electricity often exceeds the current load limit of the grid. At this time, the surplus electricity is intelligently delivered to the battery energy storage system, where it undergoes a series of precise conversion and storage processes, efficiently stored in battery units, ready for release when power is scarce. When wind speeds decrease and the output power of wind turbines is insufficient to meet grid demand, the previously stored electricity in the batteries can be released to supplement the grid.
The power balance equation for a wind farm integrated with a BESS can be written as:
$$
P_{wind}(t) + P_{BESS}(t) = P_{load}(t) + P_{loss}(t)
$$
where \( P_{wind} \) is wind power generation, \( P_{BESS} \) is the power from the battery energy storage system (positive for discharging, negative for charging), \( P_{load} \) is the load demand, and \( P_{loss} \) represents system losses.
2.2 Application of Battery Energy Storage System in Solar PV Power Stations
The solar PV power generation process has inherent volatility. Under the combined influence of various uncontrollable factors such as changing weather and sunlight intensity, the output power of a PV station is unstable. On sunny days with ample sunlight, the generation efficiency of the PV station increases significantly, and its output power rises accordingly. However, on cloudy, rainy days, or at sunset, the generation efficiency drops substantially, and output power decreases. This volatility of solar PV, if not properly managed and balanced, can have a non-negligible negative impact on grid stability and reliability. For example, during peak PV generation hours, if the grid cannot absorb the excess electricity in time, it may cause voltage rises and frequency instability. Conversely, during low PV generation periods, insufficient grid supply may lead to power outages and equipment damage. To effectively address the volatility of solar PV, battery energy storage systems are applied in PV stations. A battery energy storage system is efficient, flexible, and dispatchable, capable of real-time reflection of changes in PV power output. When PV generation exceeds the current load limit, the BESS can quickly absorb the excess electricity and store it in the batteries, forming a dispatchable storage capacity, which not only avoids energy waste but also provides a stable backup power source for the grid.
The energy management strategy for a PV-BESS system can be described by the following optimization problem:
$$
\min \int_{0}^{T} \left( C_{grid}(t) \cdot P_{grid}(t) + C_{BESS}(t) \cdot \left| P_{BESS}(t) \right| + C_{penalty}(t) \right) dt
$$
subject to constraints such as SOC limits, power limits, and grid connection requirements.
3. Coordinated Control Strategy of Battery Energy Storage System and Wind-Solar PV System
The coordinated control of battery energy storage systems and wind-solar PV systems is an important technological innovation in the field of modern renewable energy power generation, helping to optimize the overall performance of the battery energy storage system. In practice, this coordinated control relies on an efficient data acquisition and analysis system that can capture real-time data on wind-solar PV generation status, grid load demand, and key parameters of the BESS, such as state of charge, charging/discharging status, and rates. By comprehensively analyzing and processing these data, the system can accurately predict future energy supply and demand trends, providing a scientific basis for subsequent scheduling decisions. By constructing a mathematical model of the battery energy storage system, the physical characteristics of the BESS can be fully reflected, including but not limited to charge/discharge efficiency, energy density, thermal management performance, and life degradation. On this basis, the model must also possess strong computational capabilities to determine the optimal charge/discharge power and state of charge for each time period, ensuring that while suppressing wind power fluctuations, the service life of the battery energy storage system is maximized, and economic benefits are enhanced.
The coordinated control strategy between the BESS and the wind-solar PV system is an important component of modern smart grid development, providing strong support for efficient energy utilization, stable grid operation, and maximized economic benefits. The core of this strategy is to combine the BESS with the wind-solar PV system closely through advanced control technologies and algorithms, forming a synergistic whole to effectively address the discontinuity and uncertainty of renewable energy generation. This process not only helps us deeply understand the role of the BESS in balancing power supply and demand in wind power generation but also allows us to extend this successful experience to the solar PV field. By effectively coordinating and controlling the solar PV system, the reliability and sustainability of renewable energy can be further enhanced, ensuring stable output under different weather and lighting conditions. Moreover, implementing this coordinated control strategy can promote the rapid development of the clean energy industry, reduce dependence on traditional fossil fuels, and thus contribute significantly to the transformation of the global energy structure and the achievement of sustainable development goals. By continuously optimizing the coordinated control strategy of the BESS and the wind-solar PV system, we aim to achieve a green, low-carbon, and efficient energy future.
A typical coordinated control algorithm can be represented as:
$$
P_{BESS}^*(t) = K_p \cdot (P_{target}(t) – P_{wind+PV}(t)) + K_i \int_{0}^{t} (P_{target}(\tau) – P_{wind+PV}(\tau)) d\tau
$$
where \( P_{BESS}^* \) is the desired power reference for the BESS, \( P_{target} \) is the desired net power output, \( P_{wind+PV} \) is the combined generation from wind and PV, and \( K_p \), \( K_i \) are proportional and integral gains.
Table 2 summarizes the key performance characteristics of different coordinated control strategies.
| Strategy | Advantages | Disadvantages | Typical Application |
|---|---|---|---|
| Rule-based Control | Simple, fast response | Not optimal for all conditions | Small-scale systems |
| Model Predictive Control (MPC) | Optimal, handles constraints | Computationally heavy | Large-scale systems |
| Fuzzy Logic Control | Robust, handles uncertainty | Rule design expertise required | Hybrid systems |
| Reinforcement Learning | Adaptive, self-learning | Training data intensive | Future smart grids |
4. Conclusion
Through the study of battery energy storage technology in wind-solar PV systems under the low-carbon concept, we have found that battery energy storage systems have significant advantages in improving grid stability, optimizing energy configuration, and promoting efficient utilization of renewable energy. Different types of battery energy storage technologies have their own characteristics and are suitable for different application scenarios and needs. In the future, we should continue to strengthen the research and development of battery energy storage technology, promote its deep integration with wind-solar PV systems, and contribute to the realization of low-carbon energy transformation and sustainable development goals. At the same time, attention must be paid to the environmental impact and safety issues of battery energy storage technology to ensure that while promoting energy transformation, it also meets the requirements of environmental protection and sustainable development.