Abstract: In order to improve the efficiency of photovoltaic energy storage automatic balancing control, a photovoltaic energy storage automatic balancing control system is designed. This article first introduces the background and significance of the research, emphasizing the importance of improving the reliability and economic efficiency of power supply in power distribution networks. Subsequently, the hardware and software design of the system are described in detail, highlighting the application of advanced automation technology in achieving balanced control of solar energy storage. The results of system testing demonstrate its effectiveness and efficiency.
Keywords: Photovoltaic energy storage, Automatic balancing control system, Electric energy dispatch
1. Introduction
Power distribution networks serve as the terminal networks of power systems, and their reliability directly determines the safe provision of electrical energy to users. With the continuous expansion of power system construction, the focus of power distribution tasks has shifted towards providing users with safe, reliable electrical energy while enhancing the economic efficiency of power supply. In this context, large-scale renewable energy generation, represented by solar systems and energy storage systems, is gradually being integrated into power distribution networks. However, solar generation exhibits significant randomness and nonlinearity, making it challenging to accurately determine the maximum power point in the short term. Load fluctuations are also large, necessitating the use of solar energy storage balancing control systems.
2. Hardware Design of the Solar Energy Storage Automatic Balancing Control System
Table 1: Specifications and Parameters of the System Switch
| Item | Parameters |
|---|---|
| Ports | 24×10/100/1000BASE-T RJ45 | 4×10G SFP+ |
| Switch Capacity | 128Gbps |
| Power Supply | 2 (1+1) Built-in |
| Packet Buffer | 1.5MB |
| Forwarding Rate | 95Mpps |
| Input Voltage | 100240V AC, 5060Hz, 0.8A |
| DDRIII Capacity | 512MB |
The controller selected for the system is the FS-AC326 wireless AP controller, capable of providing enterprise-level functionality and capacity for user wireless LAN services. It features a throughput of 6G, supports 2 USB ports and 1 control port, and can manage up to 32 APs.
The system power supply is an uninterruptible power supply (UPS) equipped with an SNMP remote network management card, allowing for remote monitoring and control of the UPS via an RJ-45 interface.
The system employs an S3900-24T4S 24-port L2+ switch, equipped with advanced Broadcom chips to extend performance to the network edge. It supports features such as QoS, LACP, ACL, and IGMP snooping, ensuring flexible operation and automatic control of network traffic.
3. Software Design of the Solar Energy Storage Automatic Balancing Control System
3.1 Electric Energy Dispatch and Smooth Output
The designed solar energy storage automatic balancing control system aims to control electric energy dispatch and smooth output. By setting time thresholds for energy absorption and release by the solar energy storage system, the system can selectively perform smoothing control based on real-time recordings of solar grid-connected power generation voltage fluctuations, enhancing the stability of automated system operation.
Considering the three-phase imbalance characteristics of solar energy storage, a low-absorption and high-release charging and discharging mode is adopted to fully utilize power that the grid cannot absorb, allowing it to participate in power peaking. With minimizing system costs as the core objective, solar energy storage capacity is optimized, reducing the difference between actual solar power output and the target value, and enabling unified dispatch of the solar energy storage system.
3.2 Design of the solar Energy Storage Automatic Balancing Control Unit
The solar energy storage system operates in two modes: grid-connected and off-grid, which share similarities and correlations. Maximum Power Point Tracking (MPPT) technology is employed to ensure optimal system efficiency by monitoring and adjusting the solar system’s operating point.
The system output power P is calculated as:
P = P_a + P_g (1)
Where P_a is the actual output power of the solar energy storage system inverter, and P_g is the grid power.
The control parameters are automatically adjusted based on real-time monitoring and analysis of inductance energy accumulation and release within the system, maintaining energy balance under steady-state operating conditions. When the inductance energy accumulation equals the release energy in the solar energy storage system, energy reaches a balanced state, and the system completes automatic balancing control.
4. System Testing
4.1 Testing Preparation
The system was built according to the proposed design process, with solar control strategies, energy storage control strategies, and inertia damping adaptive VSG control strategies applied. VSG simulation parameters were set as follows: rated phase voltage amplitude of 311V, rated frequency of 50Hz, rated angular frequency of 100π rad/s, filter capacitance of 200μF, and switching frequency of 10kHz.
4.2 Results Analysis
Six different types and specifications of batteries, labeled XDC-01# to XDC-06#, were used to estimate the state of charge (SOC) online, with an equilibrium threshold set at 2%.
The solar energy storage automatic balancing control time is a critical indicator for evaluating the performance and efficiency of the battery solar energy storage system. It represents the time required for the system to detect, initiate, and complete the balancing operation. A comparison of the solar energy storage automatic balancing control time between the designed system and a system without the design was conducted.
From Figure 1, it is evident that the designed system consistently achieved solar energy storage balancing control within 2s across all six battery types and specifications, demonstrating significant automation performance advantages and high system operation and automatic balancing control efficiency.
5. Conclusion
To enhance the efficiency of solar energy storage balancing control, this paper designs solar energy storage automatic balancing control system, aiming to improve the energy structure of power systems, ensure safe and reliable operation, and increase the efficiency of solar energy storage automatic balancing control. The system can complete automatic balancing control within a short time, stabilizing the SOC of solar energy storage, thereby holding significant research importance.