Containerized Battery Energy Storage System
Lithium Ion batteries account for 90% of global investment into battery energy storage in 2020-21. Used to maximize savings and performance there are many vital components to this system.
Battery Systems
A battery can be broken down into different units:
Each cell converts stored chemical energy into electrical energy. These cells are combined to in parallel or in series to form a tray. The tray should be packaged with a BMS (battery mgmt system). These trays are stacked to form a battery rack.
Battery Management System
BMS performs several critical functions and is the brain of the system to protect the battery and ensure it operates correctly (charge state, voltage, current, temp). Any imbalance across a battery bank can cause stress to the cells and reduce the overall cycle life of the battery. More sophisticated battery mgmt systems like those used by EVESCO, have a multi-tiered framework that allows real-time monitoring and protection of the battery using sophisticated algorithms to analyze the data, control the battery's environment, and balance it, not just at the cell level but the module, string and system level. Critical to prevent thermal runaway and combustion.
Power Conversion Systems (PCS) or Hybrid Inverters
Similar to PV solar, a Li-Ion bank requires an inverter to produce AC which is usable in buildings. Also referred to as Power Conditioning Systems or Battery Hybrid Inverters - more dynamic than typical PV inverters due to their bi-directional functionality, enable flow from either DC or AC, charge or discharge. The hybrid inverter is informed of available capacity where the PCS directs the energy flow by commanding the battery’s charge and discharge behavior. There are two types of configuration of the PCS: AC-coupled and DC-coupled.
AC-coupled is when the energy storage system is connected external to the soler PV system on the AC side of the inverter.
DC-coupled is when the battery is connected to the same DC bus where the solar PV lands - utilizing a hybrid inverter that is shared between the PV and BESS.
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Controller
The BMS is the brains of the battery system, then the controller if the brain of the entire system. Controls, monitors, protects, communicates and schedules the key components - substations. The controller also communicates with devices such as electricity meters and transformers. Possessing multiple levels of protection, overload and reverse power protection in discharging, the controller can integrate with third-party SCADA and EMS for complete data acquisition and energy management.
HVAC and Fire Suppression
HVAC is an integral part of a battery energy storage system; regulating the internal environment through air movement within and outside of the enclosure. This helps protect and prolong the life-cycle of the battery system, prevent overheating, increased degradation, malfunction or even thermal runaway.
Fire suppression is an additional layer of protection provided within a BESS system. In the case of thermal runaway, BESS cannot rely purely on only one layer of protection. The fire suppression will activate; this could be actiated by gas, smoke, or heat detection. once sterted the fire suppression system will release an agent which suppresses the fire, providing a cooling effect and absorbing the heat.
SCADA systems
SCADA focusses on monitoring and controlling the components within the Battery Energy Storage System, it communicates with the controller via PLC. SCADA typically communicates with the BMS for monitoring battery status but can also communicate with the PCS/Hybrid inverter and auxiliary meters. Operators can issue start/stop commands, charge/discharge commands, set parameters for the BMS aux systems via HMI. It is possible that SCADA can take on the role of an EMS.
Energy Management System
The energy management system is in charge of scheduling the energy storage system activity. The EMS communicates directly with the PCS/Hybrid inverter and the BMS, brining in additional data points from things like the electric grid, transformers, PV arrays, and loads. The EMS is responsible for how and when to discharge power, typically decided by the application specifics such as peak shaving, load shifting, or self-consumption.
The EMS optimizes performance balancing application cycling data and battery life with the asset's return on investment while still considering the limitations of the BMS and PCS/Hybrid Inverter. It will also collect and analyze performance data, making reporting and forecasting simple.
At EVESCO, the BESS comes in rugged containerized enclosures and all 5ft, 10ft and 20ft systems are fully assembled before shipment. Plug and Play at its finest.