WG B3.55, Design guidelines for substations connecting battery energy storage solutions

Incorporation of intermittent renewables is a key enabler of carbon reduction in the electricity sector.  These power plants can alter the power flow pattern of the electrical system leading to reverse power flows, power variations and power supply balancing challenges.  One method of addressing these challenges is the use of battery energy storage systems (BESS).  This solution is becoming more attractive with the improvement in battery technology and the reduction in battery prices.  The substation is an ideal location for installation of large-scale batteries, although there is limited experience in this solution. WG B3.55 has produced Technical Brochure 869 on “Design Guidelines for substations connecting battery energy storage solutions.  Crina Costan was the Australian member on the working group. 

The Technical Brochure (TB) provides knowledge and guidelines for the implementation of BESS into the substation across its life-cycle from design and development through to commissioning and asset management.  Practice may vary from project to project depending on the battery technology used and service conditions but the guideline may also be used to provide a general understanding of system requirements for the BESS design.

 Current challenges for the power system as the levels of renewables increase include: 

• Reduced system strength
• Reduced inertia
• Low system fault levels
• Changing system load profile
• Fuel inefficiency,
• Implementation of government policies to accelerate the implementation of Net Zero
• Power grid congestion 

The TB discusses how the functionality of BESS can be used to help solve these problems. 

System technical requirements that must be considered when installing the BESS are covered including, compliance with grid codes, network reconfiguration, application in microgrids, the limitations of existing equipment, system grounding, environmental requirements and the hazards of BESS. 

The TB also discusses design guidelines to maximise space utilisation and whether to install indoors or outdoors.  It also covers fire risk mitigation.  Control and protection issues due to the BESS installation are also covered as well as the efficiency and evaluation of the BESS output. 

Installation and commissioning experience for each type of BESS technology is reviewed as well as safety issues such as fire risks.  The guidance focusses on sodium-sulphur and lithium-ion batteries as these are currently the most common.  Manufacturer’s recommended testing and standard requirements are also considered from factory acceptance through to on-site testing. 

The TB discusses spare parts and maintenance requirements to ensure ongoing efficient operation. This is quite critical as the technology is evolving quite quickly and parts availability and ongoing compatibility with newer versions of the technology may not be able to replace the existing plant.

BESS is a new technology for many utilities and development and training of substation staff will be required.  This will need to include issues such as special tool requirements, the changing nature of designs and the availability of spare parts.

 Various BESS aspects that need special consideration in substation design include: 

• Coordination with microgrids
• Dimensioning system studies and fault ride through
• The bi-directional flow impact on protection
• Auxiliary power supply demands
• Protection review for the loads downstream of the BESS connection when in islanded mode
• Earth grid design
• SCADA signal points and control system integration
• Fire safety
• Cyber-attack 

Connection of BESS to the power grid will provide many benefits due to its various capabilities and functions and this TB will provide a very valuable guide to help ensure safe, reliable and efficient installations are made. 

The TB can be downloaded from e-cigre and is free for members and 190€ for non-members.