The battery energy storage system BESS integrates battery system with power conversion system that can connect with the power grid. It can be in the form of a cabinet or a container for outdoor use. The direct current from the battery system can be inverted and delivered to the grid, while the alternate current can be rectified and charged into the battery system. The locally stored energy can be used for charging electrical vehicles and machineries, and other electrical devices. It can also store energy for load balancing services of the grid. The BESS can be monitored and controlled by BMS, EMS, and SCADA.
This is a general diagram of a BESS
A battery cell is the fundamental building block of a battery. It is typically an electrochemical device enclosed in a metal casing. The battery cell stores and releases electrical energy through chemical reaction, converting chemical energy into electrical energy. A battery cell usually consists of a positive elctrode cathode, a negative electrode anode, a separator, and an electrolyte.
A battery module is a battery system and typically consists of several battery cells, connectors, a Battery Management System (BMS), and an enclosure. The primary function of a battery module is to connect multiple battery cells together to increase the battery system’s voltage and energy storage capacity. The BMS normally contains a Battery Modul Unit BMU.
A battery cluster is an integrated unit formed by assembling multiple battery modules together to store and supply electrical energy. It is a higher-level component in a battery system, typically comprising multiple battery modules, connectors, and a Battery Management System BMS, a thermal management system, electrical interfaces, and an enclosure. The BMS contains a Battery Cluster Unit BCU and monitors parameters such as cell voltage, temperature, and current, performs battery state estimation and balance control, and prevents overcharging, over-discharging, over-temperature, etc. It also provides communication interfaces for data exchange with external systems.
Power Conversion System PCS
A power conversion system is a component connected between the energy storage battery system and the power grid. The battery system within the BESS stores and delivers electricity as Direct Current DC, while most electrical systems and loads operate on Alternating Current AC. A PCS serves the function of both an inverter and a rectifier.
Here is a circuit diagram
Power Distribution Unit PDU
The Power Distribution Unit, also known as a switch box, is a device with multiple power outlets that provides electrical protection and distributes power to different usages. The most basic PDUs are large power strips without surge protection.
Battery Management System BMS
The Battery Management System monitors the battery’s health, output, voltage, temperature, fire warning, and state of charge. It also regulates the charging and discharging power based on the input signal.
Energy Management System EMS
The Energy Management System monitors grid demand and how the required energy can be transferred from the BESS. This is done through control logic. The EMS sends an input signal to either charge or discharge the battery based on the control logic requirement and the SOC (State of Charge) of the battery system.
SCADA
The Supervisory Control and Data Acquisition system communicates with and controls devices throughout the whole energy storage system. It is the nerve center of the entire operation, and the means by which operators can monitor plant operations and send commands. It is possible for the SCADA to take on the role of the EMS.
The SCADA system typically communicate with the BMS directly to monitor battery readings. It may also be beneficial or required for the SCADA system to communicate with DC-DC converters, inverters, and auxiliary meters in order to properly control the BMS.
Key readings that are passed through from the batteries and stacks include SOC, current, voltage, and temperature, as well as a number of connected stacks and alarm indicators.
Liquid cooling is used for cooling the battery pack to give better security. This refers to the use of liquid cooling technology to set up a special liquid circulation channel. Liquid coolant for heat dissipation is added to the channel, and the coolant is circulated through a power pump to remove the heat generated during the charing and discharging processes of the battery.
The fire protection system is designed at two levels, the battery level and the whole cabinet level. The system consists of fire detection, fire alarm, and fire extinguishing.
At the battery level, there is temperature sensing wire within the battery pack. As soon as temperature reaches a certain level, hot aerosol will be sprayed out to extinguish the fire from the battery.
For the whole cabinet, the system is equipped with sound and light alarms for fire detection, and for release of fire extinguishing agent.
heptafluoropropane fire extinguishing device
Temperature and humidity control
The temperature and humidity control consists of four parts: a compression-based mechanical cooling system, a heating system, a ventilation system, and a control system. The control system automatically controls and coordinates the process based on indoor and outdoor temperature and humidity, and implements functions such as natural air cooling, compression-based mechanical cooling, heating, and dehumidification.
The system has the following features:
1. Power-off memory and automatic restart; remote fault identification and alarm; remote communication control; fuzzy smart control;
2. Lifespan is close to 10 years. The continuous operation time without failure is about 35,000 hours under rated voltage and ordinary working conditions.
3. Strong ability to function in harsh environments.
1~230VAC, 3~400VAC, 24VDC
