With the rapid development of the social economy, the demand for energy is increasing year by year. The depletion of fossil fuels and the intensifying energy crisis have made the development of renewable energy an urgent task. Solar and wind energy, as clean and inexhaustible energy sources, are crucial for alleviating the energy crisis and improving energy security. However, the output of these renewable energy sources is highly dependent on natural conditions, making energy storage and solar inverter control technologies essential for their efficient utilization.
This chapter provides an overview of the research background and significance of battery management and solar inverter control in distributed power supply systems. It also presents the current status of research in these areas, including battery equalization management, electromagnetic radiation suppression in single-phase inverters, parallel control of single-phase inverters, and grid-connected control of single-phase inverters.
1.1 Research Background and Significance
The global energy consumption is on the rise, and the limited reserves of fossil fuels have led to an energy crisis. Renewable energy sources such as solar and wind energy are clean and sustainable, and their development is crucial for meeting future energy demands and addressing the energy crisis. In China, the proportion of solar and wind energy in the power generation is still very low, and the development of these renewable energy sources is of great urgency. The key technologies for the development of renewable energy include energy storage and solar inverter power supply control. This paper focuses on the battery management technology in the energy storage system and the solar inverter control technology in the distributed power supply system.
1.2 Current Research Status
1.2.1 Battery Equalization Management
There are currently seven main types of equalization control circuits for battery management, each with its own advantages and disadvantages. The research on optimizing the control strategy to improve the performance of the entire equalization management system is relatively limited.
1.2.2 Electromagnetic Radiation Suppression in Single-Phase Inverters
The high-frequency switching of solar inverter power supplies leads to the generation of a large amount of electromagnetic radiation, which can cause electromagnetic interference to surrounding equipment. Current methods for suppressing electromagnetic interference include controlling the rate of change of voltage and current, using filters to eliminate common-mode interference, and applying frequency modulation techniques.
1.2.3 Parallel Control of Single-Phase Inverters
The key to the parallel operation of solar inverter power supplies is to ensure the uniform distribution of load current. The output voltage and current of the solar inverter must be strictly consistent in amplitude, phase, and frequency. Any slight inconsistency can lead to power differences, resulting in large circulating currents, which reduce the efficiency and reliability of the parallel solar inverter system.
1.2.4 Grid-Connected Control of Single-Phase Inverters
The main issues in grid-connected control of solar inverter power supplies include effective control of the grid-connected current, tracking the frequency and phase changes of the grid voltage in real-time, and reducing the total distortion of the grid-connected current to minimize the impact of harmonic currents on the grid.
1.3 Chapter Arrangement and Main Innovations
1.3.1 Chapter Arrangement
The paper is divided into five chapters. Chapter 2 focuses on the battery equalization management technology in the distributed power supply system. Chapter 3 analyzes the model of the single-phase inverter and its electromagnetic radiation suppression. Chapter 4 discusses the parallel control of the single-phase inverter. Chapter 5 explores the grid-connected control of the single-phase inverter.
1.3.2 Main Innovations
- Proposed an equalization charging control strategy for the switched-resistor and fly-back converter equalization circuits, which can not only achieve fast charging but also reduce the impact of battery inconsistency on the cycle life.
- Introduced a frequency hopping modulation technique to suppress the harmonic amplitude of the single-phase inverter output voltage, thereby reducing electromagnetic radiation.
- Proposed a power flow analysis method for the parallel solar inverter power supply, decomposing the output power vector into two orthogonal sub-vectors, and deriving the control strategies for different output impedance types.
- Analyzed the relationship between the circulating current and the voltage difference and phase difference in the two-inverter parallel system, and proposed an output circulating current decoupling parallel control strategy.
- Proposed a constant frequency current hysteresis control strategy for the grid-connected solar inverter based on switch time prediction, which simplifies the control circuit and ensures a fast response speed and constant switching frequency.
1.4 Relationship between Chapters
The research on battery management and solar inverter control in the distributed power supply system is a comprehensive and systematic task. The battery equalization management in Chapter 2 ensures the performance and life of the battery pack, which is the basis for the stable operation of the entire system. The analysis of the single-phase inverter model and its electromagnetic radiation suppression in Chapter 3 improves the performance and reliability of the inverter. The parallel control of the single-phase inverter in Chapter 4 enhances the power supply capacity and reliability of the system. The grid-connected control of the single-phase inverter in Chapter 5 enables the effective integration of the renewable energy into the grid.
In summary, these chapters are closely related and form an organic whole, contributing to the efficient and reliable operation of the distributed power supply system.
The following is a summary of the research status in tabular form:
| Research Area | Key Points |
|---|---|
| Battery Equalization Management | – Seven types of equalization control circuits – Limited research on control strategy optimization |
| Electromagnetic Radiation Suppression in Single-Phase Inverters | – High-frequency switching causes electromagnetic radiation – Methods for suppressing interference include controlling voltage and current changes, using filters, and applying frequency modulation |
| Parallel Control of Single-Phase Inverters | – Ensuring uniform load current distribution is crucial – Slight inconsistencies can lead to circulating currents and reduce system efficiency |
| Grid-Connected Control of Single-Phase Inverters | – Effective control of grid-connected current and tracking grid voltage changes are important – Reducing harmonic currents is necessary to minimize the impact on the grid |