With the progress of the times and the rapid development of the national economy, energy and mineral resources are increasingly scarce. It is urgent to explore renewable energy as a substitute for existing non renewable energy sources. As a green energy source, solar photovoltaic power generation has received high attention from the country, and support is increasing day by day. The technology of solar photovoltaic grid connected power generation is also keeping up with the times, constantly innovating, and creating considerable social and economic benefits.
1. Design and system advantages of solar photovoltaic grid connected power generation system
1.1 System Design
The solar photovoltaic grid connected power generation system uses inverters as the carrier to play its own role, providing electricity to households and enterprises. The system includes solar photovoltaic cells to collect solar energy. The power generation system can be installed in environments such as building roofs, deserts, and Gobi to ensure that solar photovoltaic cells can store energy in a state of sufficient solar energy. DC/DC belongs to the power tracker, which can ensure that the power of the solar photovoltaic grid connected power generation system remains stable, play the role of a battery, and effectively schedule solar photovoltaic power generation projects. DC/AC, also known as inverters, is a device that connects the power grid to a solar photovoltaic power generation system. By applying this system, the stability of the connection can be enhanced. The investment in a large number of solar photovoltaic power generation projects can promote the intelligent development goals of the power grid, improve the promotion efficiency of solar resources, and effectively alleviate the supply pressure of traditional electricity.
1.2 Advantages of Solar Photovoltaic Systems
(1) The application of renewable clean energy such as solar energy eliminates the need to consume non renewable carbon containing fossil fuels. In practical applications, clean energy does not generate greenhouse gases and other pollutants, protects the ecological environment, and can meet the requirements of sustainable and harmonious social and economic development.
(2) The energy generated by the system is effectively integrated into the power grid, using electrical energy to store energy without the need for battery packs. Compared with independent solar photovoltaic systems, the construction investment cost is reduced by 35% to 45%, and the power generation cost is significantly reduced. At the same time, without the use of battery packs, it effectively improves the average failure rate of the system and the secondary pollution time of the battery pack.
(3) Distributed installation, that is, the power supply is distributed locally. The power grid has strong flexibility in advance and retreat, effectively improving the power system’s ability to withstand disasters, gradually improving the system’s own load balance, and reducing line losses.
(4) Fully leverage peak shaving effectiveness. At present, in developed countries, solar photovoltaic applications and connected solar energy have become the core of technological competition, becoming one of the important methods of solar photovoltaic power generation worldwide, with great development space and promising prospects.
2. Key points of solar photovoltaic grid connected power generation technology
2.1 Power point circuit tracking control technology
In solar photovoltaic systems, the maximum power point of solar cells is an important component. The intensity of light and external temperature have a significant impact on the output of solar cells. When the light intensity and external temperature conditions are the same, solar cells have different operating voltages and output powers. The maximum power point tracking control technology of solar cells refers to ensuring the maximum output of solar energy under current light intensity, based on the full utilization of solar resources. This plays a very important role in improving the overall efficiency of the system. At present, there are many methods for tracking and controlling the maximum power point circuit, among which fixed voltage, disturbance observation, and incremental conductance are more common. In addition, researchers have applied control methods such as fuzzy and sliding film to the tracking control of maximum power points, achieving significant results. These methods can effectively track and adjust the maximum output power of solar photovoltaic devices, but they all have certain drawbacks. How to make solar photovoltaic devices conveniently and stably output the maximum power point is an important issue that urgently needs to be solved in the current solar photovoltaic grid connected power generation system.
2.2 Inverter Technology
The grid connected inverter provides a certain degree of flexibility for the solar photovoltaic grid connected power generation system, which can meet the diverse needs of the project and maintain the optimal conversion state of solar energy. In addition, the inverter also plays an important control role, which can directly or indirectly control the current. In recent years, with the progress of the times and the increasing level of modern technology, the indirect and direct integration of control technology has been continuously enhanced, and the effect of direct or indirect current control has become more obvious. After the fusion of the two, the grid connected inverter control technology can track the changes in current in real-time, making the current more stable. The core of inverter control technology mainly includes: (1) CNC technology, which is the foundation of grid connected inverter control technology and belongs to a thermoelectric technology; (2) PID control technology can ensure more stable operation of inverters through full or incremental methods, making the development of technology more mature; (3) Repetitive+PI hybrid control technology, which has strong complexity, utilizes a composite method to control the operation of the inverter and enhance stability.
2.3 Solar photovoltaic grid connected distributed technology
Distributed grid connection technology utilizes solar photovoltaic power generation systems to distribute electrical energy and achieve direct allocation of electricity usage ratios. Once there is a shortage of electricity, it is necessary to conduct real-time regulation and bidirectional exchange with the large power grid. The distributed solar photovoltaic power generation system includes components such as solar panels, protection devices, circuits, inverters, and power grid interfaces. Among them, solar panels are the core equipment of solar photovoltaic power generation systems, which can convert solar energy into electrical energy. The inverter is responsible for converting direct current and forming specialized AC equipment. Due to the inclusion of direct current in battery components, inverters can form AC loads in practical applications to supply power to the National Grid.
2.4 Accurately Judging Grid Connected Power Generation
During the operation of solar photovoltaic grid connected power generation systems, the power generation can be accurately predicted, and the predictive effect can be used to determine various interference situations that may occur during system operation, and effective measures can be taken to minimize their impact. At the same time, the application of this technology can effectively improve the overall level of solar photovoltaic grid connected power generation systems. There are two main prediction methods: indirect and direct. Timely identification of potential influencing factors can improve system conversion efficiency and comprehensively predict grid connected power generation. In addition, when predicting functions, it is necessary to strictly process various data and strive to fully utilize the predictive power of the system.
2.5 System Security Technology
During the operation of solar photovoltaic grid connected power generation systems, security technology can effectively prevent isolated islands and play a proactive role in protecting the system’s operation. In the process of applying this technology, real-time simulation experiments are conducted to observe and analyze the load data appearing in the power grid, which can timely predict the possibility of power outage in the power grid, effectively control the inverter, and comprehensively protect the solar photovoltaic grid connected power generation system.
3. Practical analysis of solar photovoltaic grid connected power generation system
3.1 Project Overview
The solar photovoltaic power generation grid connected system constructed by a certain enterprise is located on the roof of the company’s building, with a total peak design power of 3360 Wp. Due to its direct connection to the company’s power grid, once the power grid is cut off, it can independently provide load charges to the enterprise and provide operational energy for the night view e-commerce of the display platform. The battery panel adopts dual glass photovoltaic modules, namely tempered ultra white 6mm glass+EVA+battery pack+EVA+tempered ultra white 6mm glass. After the project started operation, the grid connected system has been maintained in a safe, reliable, and stable state, meeting the project design requirements. Based on the geographical location and natural environment of the project, calculations have found that when the solar panel is positioned in a positive south direction with an inclination angle of 25 ° to 30 °, it receives the highest solar radiation and generates the maximum electricity. To facilitate project construction and the production of solar cell brackets, it is required to have a solar photovoltaic installation area of 130 square meters in a 27 ° angle direction.
3.2 Specific Practice of Solar Photovoltaic Grid Connected Power Generation System
(1) Electrical equipment. In solar photovoltaic power generation projects, control equipment such as solar cells, battery packs, bidirectional and grid connected inverters are the main electrical equipment system components.
(2) System operation principle. Effectively connect 7 solar photovoltaic cells in series, using a secondary tube assembly line to connect 12 sets of series cells in parallel to form a set of output inverters, and their AC power is directly connected to the company’s power grid, with the middle connected to a bidirectional inverter and battery pack. When encountering a power outage, the battery pack can be switched to in a timely manner to provide power to the load. When solar cells generate electricity normally, they first charge the battery pack through a bidirectional inverter. When the battery pack reaches its full charge state, the solar energy generated by the solar cell is directly inverted into the power grid. If encountering a power outage and the voltage loss release is successful, the bidirectional inverter receives relevant information and starts the inverter. The battery pack is applied to achieve load power supply.
(3) Digital monitoring system. In this project, the monitoring system mainly includes equipment such as laying illuminators, temperature and anemometers, governors, controllers, and terminal control and data cables. At the same time, use computer terminals to display screens and monitor relevant data in real-time; Utilize the program conversion interface to easily convert the display interfaces of terminals such as computers and televisions. On this page, important information such as system temperature, DC voltage, AC voltage, daily power generation, total power generation, and meteorological data can also be displayed, truly reflecting the actual operation of the system.
4. Suggestions and development prospects for optimizing solar photovoltaic grid connected power generation technology
4.1 Optimization of solar photovoltaic grid connected power generation technology
With the progress of the times and the continuous improvement of modern technology, solar photovoltaic grid connected power generation systems also need to continuously optimize and update their own technology. Among them, the battery reserve system should be the focus of optimization, and battery or solar systems with longer energy storage time should be selected as much as possible to effectively connect the battery and solar photovoltaic power generation module, build basic power equipment for the solar photovoltaic power generation system, and promote the regular operation of electricity. After long-term use, solar panels can use light current to drive various equipment and devices, convert direct current into alternating current through inverters, or use grid connected inverters to ensure that the system maintains consistent current output with the power grid.
4.2 Effective control of solar photovoltaic grid connected power generation system
There are three main control strategies: hysteresis loop, dual loop, and space vector PWM. Among them, hysteresis control can quickly respond to current, but its power device switching frequency is not stable enough, and there are no special harmonics in the voltage and current output waveform, which to some extent increases the difficulty of system parameter design. Double loop control is the use of voltage, current and other control methods to stabilize and regulate the amplitude of grid connected current through direct current electrohydraulic control. This control method has a fixed switching frequency and a simple system design, but when the switching frequency is low, the dynamic response speed of the current is slower. The SVPWM control method is a new control method that utilizes inverter space voltage or current vector conversion to effectively control the inverter. When faced with low switching frequency of power devices, their sine wave output quality is good, which to some extent significantly improves the efficiency of using DC voltage.
4.3 Future Development Prospects of the System
In recent years, China has conducted certain research on solar photovoltaic power grid connection systems and achieved significant results. However, in the field of solar photovoltaic grid connected power generation control and switching, more in-depth research and analysis are urgently needed. In order to effectively improve the operational efficiency of solar photovoltaic grid connected power generation systems, based on a deep understanding of system control, it is necessary to ensure that system switching issues are properly resolved, expand the application scale of solar photovoltaic grid connected power generation systems, and expand the range of beneficiary users. Essentially, solar photovoltaic grid connected power generation systems have the advantages of solar power generation technology, but their own construction costs are high, investment is high, and power generation is greatly affected by climate and environment, which is currently a problem that needs to be solved in this power generation system.
5. Conclusion
With the rapid development of the national economy, the shortage of resources and environmental pollution in the power industry have attracted much attention. The mature development of new solar photovoltaic grid connected power generation systems has brought a dawn to the power industry. When applying solar photovoltaic grid connected power generation systems, it is necessary to do a good job in system planning and design to avoid affecting the efficiency of grid connected operation. At the same time, various safety protection measures should be implemented in place, and problems in system operation should be identified and improved in a timely manner to ensure the safe and stable operation of the solar photovoltaic grid connected power generation system.