In photovoltaic power generation systems, the scientific and reasonable application of energy storage devices can effectively reduce power changes caused by fluctuations in the actual operation of photovoltaic power generation systems, reduce power changes, and reduce the impact on the grid and load, ensuring that photovoltaic systems can achieve a smooth transition under off-grid conditions, effectively improving the operational quality of the power supply system. However, in the actual setting process, the setting of the energy storage unit can use valve controlled sealed lead acid batteries. Based on the analysis of the operating characteristics of the photovoltaic power generation system itself and the operational advantages of the energy storage unit under different operating conditions, a complete charging control system and discharge control system can be established, and their effectiveness can be verified using targeted management measures.
With the guidance of national policies and the proposal of carbon peaking and carbon neutrality, new energy power generation systems represented by photovoltaic power generation technology are increasingly entering the market and integrated into the grid. Due to the intermittence and volatility of photovoltaic power generation systems, some phenomena of light abandonment are particularly serious in northwest China. Therefore, it is necessary to combine energy storage technology with large-scale power stations in the construction of photovoltaic power generation systems to improve the absorption capacity of solar energy and avoid resource waste.
1. Composition of photovoltaic grid connected power generation system
The photovoltaic grid connected power generation system is mainly composed of relay protection devices, photovoltaic arrays, inverters, energy storage devices, and maximum power point tracking devices. In order to ensure that the voltage and current are at the same frequency, the most fundamental link in the entire photovoltaic system is the photovoltaic array. The photovoltaic array can be used to convert solar energy into electrical energy, and then it can be installed in series and parallel on the bracket through the battery cell according to the actual needs of voltage and current. However, the array of photovoltaic cells has strong nonlinear characteristics, mainly due to the impact of various factors such as load illumination and temperature during the power output process. The maximum power point tracking device can ensure that the battery array maintains the maximum output power at all times, ensuring that the efficient use of photovoltaic energy can be truly achieved. The energy storage device is mainly used to regulate and control the electrical energy in the photovoltaic system, storing sufficient electrical energy during the lighting process, and releasing the stored electrical energy when necessary. This can effectively regulate the power supply balance state and the output state of the power supply. Inverters are mainly used to effectively connect photovoltaic power generation systems and the power grid. Through inverters and transformers, direct current can be converted into AC power that can be used by people. They are also an important component of the entire power generation system. Photovoltaic power generation systems also have some very typical characteristics, which are affected by factors such as external temperature and light, which can affect the output power, leading to unstable and uncontrollable power generation, and the cost of the entire photovoltaic system is very high. Therefore, maximizing the absorption and utilization of solar energy and controlling operating costs are key issues that relevant staff need to address. Only by effectively improving the active power of photovoltaic power generation systems and fundamentally improving the utilization rate of solar energy can the grid connection voltage and grid connection voltage of the system be ensured to be consistent.
2. Application of energy storage technology in photovoltaic grid connected power generation
2.1 Power Peak Regulation
The most direct purpose of peak power regulation is to meet the centralized and high-power electricity demand during peak power periods, and to effectively control the load of the power grid to the maximum extent. The energy storage device can store the electrical energy generated by the photovoltaic system under relatively low loads based on the actual operation of the power grid, and then release it during peak periods, thereby ensuring the peak power output of the power grid and ensuring the reliability of the operation of the power supply system.
2.2 Load response
During the actual operation of power systems, in order to ensure the effectiveness of grid operation and minimize the probability of accidents, automatic adjustments are usually made to some high-power loads. Under high load conditions, different parts of the grid usually operate alternately, which can ensure that the operation of the grid during peak hours can meet people’s actual needs and ensure the stability of power supply. When using photovoltaic energy storage systems, power users can maximize the stability of their power supply. However, in this process, relevant personnel should also focus on the connection between the energy storage station and the power grid in the load response system. It is necessary to ensure that at least one communication line can operate normally, in order to minimize the use of high-power equipment, Really meet the response needs of the load. The use of load response technology in photovoltaic power generation systems can reduce the probability of failures during system operation by alternately applying effective options for different power grids. The use of consistent response technology can make corresponding adjustments to high power loads, ensure stable operation within the critical range, and ensure the quality of power supply, while also minimizing the amount of power supply adjustments, The adverse impact on the stable operation of the power grid ensures the safe and stable operation of the power system and maximizes the stability of the power supply.
2.3 Smooth output fluctuation
The energy source of photovoltaic power generation systems is solar energy, which cannot generate electricity at night. Using energy storage devices and related control strategies, it is possible to track the output of photovoltaic power generation systems, absorb electrical energy at the peak of output, and release electrical energy at the peak of output, thereby maintaining a smooth output power and making the prediction of photovoltaic power generation output more accurate. From the existing research results, it can be seen that battery energy storage systems have a significant role in smoothing the output fluctuations of photovoltaic power generation systems.
2.4 Increase the absorption capacity of solar energy
The northwest of China is rich in solar energy resources, which is a Class I region in China. However, the northwest of China is also a sparsely populated plateau region with low population density and small quantity. At the same time, the industry in the northwest region is relatively backward compared to other regions. Therefore, the load pressure in northwest China is far less than that in North, Central, and South China. Therefore, in the northwest region with high photovoltaic permeability, due to the mismatch between power generation and load, the phenomenon of discarding light often occurs, resulting in huge losses and negative impacts. At this time, applying the energy storage system to auxiliary services such as peak shaving and frequency modulation in the power system, through unified scheduling of the energy management system, combined with the automatic control system of the photovoltaic power station, to control the charging and discharging time and frequency of the energy storage system, can reduce the phenomenon of waste light on the power generation side, increase the absorption capacity of solar energy, improve energy utilization, and bring good economic benefits.
2.5 Improve power supply reliability
The energy storage system can play a role of peak shaving and valley filling. During peak load periods, energy storage systems can convert their stored energy into electrical energy and inject it into the grid. During the low load period, the energy storage system can absorb and convert excess electrical energy in the grid into corresponding energy forms for storage by energy storage devices, and balance the power level of the grid through peak shaving and valley filling. At the same time, the energy storage system can play a backup power function.
2.6 Improving power quality
Due to the impact of weather, temperature, component inclination, and other factors, the output power of photovoltaic power generation systems can vary, resulting in instability in power generation, increasing the difficulty of power generation prediction, and affecting harmonics fed into the grid. Moreover, with the change of solar irradiance, the photovoltaic power generation power will have a certain impact on the load characteristics in the power grid flow. After the photovoltaic power generation system is integrated into the power grid, it will have an impact on the direction of power flow, existing power grid scheduling, planned operation methods, etc., increasing the difficulty of power grid scheduling and control. When a large number of photovoltaic power generation systems are connected to the grid, voltage fluctuations will be exacerbated, causing frequent actions of voltage regulating devices, and reducing the power quality of the grid. After the energy storage is connected to the photovoltaic power generation system, the charging and discharging of the energy storage device can be controlled by the corresponding energy conversion system, which can achieve the purpose of peak shaving of the power grid and effectively control the power generation capacity of the photovoltaic power generation system. In addition, the access of energy storage devices can suppress changes in the direction of power flow, increase the stability of the grid, and improve the power quality of photovoltaic power generation systems after they are connected to the grid.
2.7 Microgrid
For power transmission systems, micro grid connection is the main trend of future development, and the use of micro grid can fundamentally improve the reliability of power supply. If the microgrid is separated from the entire power system, that is, if the microgrid is in an isolated island operation state, it can independently fulfill the power supply demand of the power load. In such cases, using a photovoltaic power generation system to form a microgrid can also play its own role, ensuring that the entire system’s power supply is safer and more reliable.
3. Conclusion
In summary, in photovoltaic power generation systems, the application of energy storage technology will involve various aspects. Enterprises should also comply with the rapid development of the times, fully apply advanced Internet technology, properly handle the application conditions and specific influencing factors of energy storage technology, try to eliminate the impact of the external environment, effectively improve the level of energy storage management of enterprises, establish a complete talent management system through effective incentive mechanisms, Establish a safer and more reliable photovoltaic grid connected power generation system in strict accordance with the principles of adjusting measures to local conditions and overall planning, to provide people with more stable electric energy.
