Typical Three-Level Architecture of a BMS for Energy Storage Power Plants

A BMS typically adopts a three-level architecture (slave control, master control, and master control) to achieve hierarchical management and control from battery modules to clusters to stacks. The following briefly describes the three-level architecture of a BMS system.

Level 1: The Battery Management Unit (slave control), commonly called the BMU (Battery Management Unit). Due to the lack of a strict, standardized name, some manufacturers also refer to it as the ESBMM (Energy Storage Battery Management Module) or the CSU (Cell Supervision Unit). This level primarily collects battery cell voltage and temperature data and is responsible for executing battery balancing strategies. This information is communicated to the second level via a communication link, typically using CAN or daisy chain communication.

Level 2: The Battery Cluster Management Unit (master control), commonly referred to as the BCU (Battery Cluster Management Unit) or ESBCM (Energy Storage Battery Cluster Module). This level's primary functions include collecting battery cluster voltage, current, and insulation information, controlling battery pack protection contactors, collecting information from the first-level BMU, and estimating the battery state of charge (SOC). This information is then communicated to the third level via a communication link, typically using CAN or Ethernet.

The third level: The BMS system management host or stack management unit (master control), commonly referred to as a BSU (Battery Stack Management Unit), ESMU (Energy System Management Unit), BAMS (Battery Array Management System), or BAU (Battery Array Unit). This level's primary functions include collecting, storing, and displaying information transmitted by the second-level BCU. It also provides real-time alarms, control of the main circuit breaker, and contact feedback. It also provides real-time communication with the PCS, EMS, and on-site monitoring systems. The BSU also transparently transmits and controls information from dynamic and environmental equipment such as air conditioning and fire protection systems. The BSU typically communicates with the EMS via Ethernet and with the PCS via RS485 or CAN.