An Overview on Battery Energy Storage Systems

An Overview on Battery Energy Storage Systems

Posannapeta Y Ganga Ram

Ph.D. Research Scholar, Shri Venkateshwara University, Gajraula, India

Dr. Sharad Kumar

HOD, School of Engineering Technology, Shri Venkateshwara University, Gajraula, India

Abstract Storage of electrical energy is the most important now a days. Why because renewable energy plants (i.e. solar power plants and wind power plants) are growing like anything, these are purely dependent on wind-availability and sunshine- availability. So, BESS-battery energy storage systems are mandatory to store this renewable energy in the high-capacity batteries. In this paper, it describes MW-Range BESS system overview including main components, charging / discharging and maintenance tips.

Key words: BESS, Battery energy, Storage system, BMS, PCS, Charge, Discharge.

1. INTRODUCTION

   A battery energy storage system (BESS) captures energy from various sources (renewable / nonrenewable) and stores it in rechargeable batteries for later use.

   Fig 1: Battery Energy Storage System Unit

   A battery is a DC (Direct Current) device and when needed, the electro chemical energy is discharged from the battery to meet the electricity demands.

   In addition to batteries, BESS also requires some additional components that allow the system to be connected to an electrical network.

   1. A Bidirectional inverter / Power Conversion System (PCS)

   2. Energy Management System (EMS)

2. BESS MAIN COMPONENTS

   1. Batteries: It stores electrical energy in the form of chemical energy.

   2. A Bidirectional inverter / Power Conversion System (PCS): It is the main device that converts power between the DC battery terminals and AC line and allows the power to flow in both directions simultaneously during charging and discharging of the batteries.

   3. Battery Management System (BMS): BMS ensures the battery cells safe working operation, ensuring it operates within the correct charging and discharging parameters in doing so, the BMS monitors the battery cells current, voltage and temperature and estimates its SoC and SoH.

   4. Energy Management System (EMS): EMS controls and monitors the energy flow of the BESS and systems. The EMS coordinates the BMS, inverter and other components of the battery energy system by collecting and analyzing data.

3. SPECIFICATIONS OF BATTERY

   CONTAINER

   Battery Cell Specifications-

   Here 44-Cells are connected in series to form a battery module.

   Battery Module Specifications-

   Battery Rack Specifications-

   Here 9-Modules are connected in series to form a battery rack, 9-battery racks are connected in parallel to form a battery container.

   Battery Container Specifications-

   Fig 2: Side View of Battery Container

4. BATTERY CONTAINER (SLD) SINGLE

   LINE DIAGRAM

   Fig. 3: Battery container SLD

5. COMPONENTS OF BATTERY CONTAINER

   Other than Batteries, BESS Container also have the following components

   • HV Box

   • HVAC System

   • LCS

   • FFS

     HV Box – (High Voltage Box): There are 9 HV boxes inside the BESS Container, and each HV box mainly comprises of Isolation Switch [1500 VDC, 250 A] and fuse [1500 VDC, 350 A].

     Fig 4: Front View of Battery Rack

     Advantage, we can isolate any individual rack in case of any fault in a particular rack, so that container can function normally, with help of healthy racks.

     HVAC System – (Heat Ventilation and Air Conditioning System): This HVAC is used to control maintain the temperature and humidity inside the container.

     LCS – (Liquid Cooing System): This LCS is used to control maintain the temperature of individual battery modules.

     Fig. 5: Liquid Cooing System

     The liquid cooling system between all the boxes is connected in parallel, and the system uses a customized cooling unit with a total flow of 320 L/min, and the flow rate divided equally into each battery pack is approx. 4 L / min at 0.5 C rate.

     FFS – (Fire Fighting System): The FFS comprises of control box, fire extinguishing section, gas ventilation and water system.

     1. Control Box – The control box includes the Heat detector and smoke detectors feedback. It includes manual release pull button to operate fire extinguisher manually. It also includes emergency stop button to shut down the container.

     2. Fire extinguishing section It includes a Per-fluoro- hexa-none fire extinguishing agent and a high- pressure release hose to extinguish fire.

     3. Gas ventilation It includes Li-ion detector to detect leakages if any, along with fan, exhaust and ventilation to quickly remove the gases from inside of the container.

     4. Water system – It is an arrangement of water fire pipe and sprinkler system to extinguish fire with help of water.

6. POWER – UP CHECKS & POWER – ON

   PROCESS

   Power-up checks:

   • Check whether the DC circuit breaker in HV Box cabinet is in disconnected state.

   • Check whether +ve and -ve DC Power cables are connected correctly.

   • Check if the battery series connection is done properly

   • Check all the communication cable terminations and LAN port connections are OK.

   • Check whether accumulative voltage values and total voltage values of the battery are accurate and system fault status is normal

   Power-ON Process:

   • First, low voltage power supply switches should be closed to ensure that three stage BMS, UPS power supply, battery cluster power supply etc. are normal

   • Then turn ON the LCS unit, FFS and other components and observe everything is normal.

   • Then close the DC circuit breaker of each rack from HV box and observe the indicator lights.

   • After the battery rack is powered up, the level 3 BMS automatically sends a closing relay command to level 2 BMS in the stack After the self-test of the second level BMS is completed, the main positive and negative relays will be closed and DC bus of 9 battery clusters will be powered ON successfully and control panel will operate to close the main circuit breaker of the combiner cabinet and the system enters charging or discharging mode.

7. CHARGE / DISCHARGE OPERATION & REAL TIME ROUND-TRIP EFFICIENCY

   The charging & discharging reading details obtained from BESS Block-05 of a site.

   From above data the Real Time Efficiency (RTE) = 88.36%.

8. MAINTENANCE OF BATTERY CONTAINER

• The ambient temperature should be maintained between 20

  – 40 deg Celsius.

• If the batteries are not used for a long time, it should be kept

  charged in (SoC 80%) every 3 months.

• Regular dust removal fom the container, and power should be cut off before removing dust. Water should not be flushed for cleaning.

• Check whether the cable connection terminal is loose, whether the terminal surface is rusted or oxidized.

• Check whether cable is aging and insulation is good or not.

• Check whether all the indications are intact and function properly.

• If the SoC value error is found then it needs to be re calibrated.

• System software needs to be updated from time to time.

Acknowledgment

I would like to thank my ex-colleague Mr. Ashwin Sharma, for grate support for his valuable input & guidance for this article.

REFERENCES:

1. Mr. Ashwin Sharma, Power Point Prestation on BESS, presented on date 01/02/2024.

2. BESS: Battery Energy Storage Systems, https://www.enel.com/learning-hub/storage/bess.

3. Battery energy storage systems (BESS) basics, https://electrification.us.abb.com/back-to-basics/battery-energy- storage-systems-bess-basics.

4. Battery energy storage system, https://power.mhi.com/regions/emea/sites/g/files/jwhtju936/files/2021

   – 11/Mitsubishi%20EU%20BESS%20presentation_final.pdf

5. Battery energy storage system, https://en.wikipedia.org/wiki/Battery_energy_storage_system

6. https://www.nationalgrid.com/stories/energy-explained/what-is- battery-storage.

About Authors:

Mr. Posannapeta Y Ganga Ram received Diploma in Electrical & Electronics engineering from S. S. Govt. Polytechnic, Zahirabad (India), B.Tech. (EEE) from J N T University, Hyderabad (India) and masters degree (M. Tech, Specialization in Elect. Power System Control) from Mysore (India). Mr. Ganga Ram, currently Ph.D. research scholar of Shri Venkateshwara University (SVU), Gajraula (India).

Dr. Sharad Kumar Head of the Department, School of Engineering Technology at Shri Venkateswara University, Gajraula since 2014. Graduated in ECE from UPTU, Lucknow (India), M. Tech Degree in ECE from Amity University, Noida (India) and Ph.D. in 2019 from SVU. Extensive experience in both theoretical and practical aspects of Antenna design, electromagnetic wave propagation, RF systems engineering.