Microgrid applications – Supply security (Part 4)

As noted in the previous blog, microgrids have a number of different application areas with some overlap between these on any particular microgrid deployment. Categories include:

• Grid, Microgrids, Nano grids and VPPs - what’s all that about? (Part 1)
• Remote or off grid systems (Part 2)
• Grid connection capacity management and market access benefits (Part 3)
• Supply security improvement (Part 4)
• Resilience applications including black start applications (Part 5)
• Driving low carbon initiatives (Part 6)
• Observations on the drivers to deploy microgrids (Part 7)

The focus of this blog is on the use of microgrids for security of supply improvements. I am making a distinction here between customer focussed initiatives to improve supply security and the use of microgrids by utility distribution network operators (DNOs), utility transmission network operators (TSO)s and private network operators to improve the resilience of grid supplies which is the topic of another blog.

This microgrid application involves improving supply security above that provided by the DNO or TSO via the public utility grid connection. Historically customers have assessed the supply security they require and, where a standard grid connection is not sufficient, they have procured additional supply security using various means including additional utility grid supply connections and connection redundancy, onsite standby generation with possible uninterruptable power supplies for seamless transition to standby power supplies. Hospitals, supermarkets, hotels, office blocks, military bases, data server facilities and many business facilities have standby supplies to achieve the level of supply security required. In many cases standby supplies are provided by diesel generators but new solutions which use renewable energy resources (RES) to displace at least an element of diesel generation, with battery energy storage system (BESS) for seamless transitions and frequency and voltage regulation, and microgrid control systems are all becoming more popular as organisations strive to reduce their carbon footprints and improve their green credentials.

One interesting public domain example is an ABB factory in their Longmeadow facility in Johannesburg, South Africa. This is an integrated solar-diesel microgrid installation with fully grid-connected and off-grid functionalities designed to maximize the use of renewable energy and ensure uninterrupted power supply to keep the lights on and the factory running during any planned or unplanned power outages on the main grid supply. The 1 MVA/380 kWh BESS, together with 750 kW of rooftop solar PV have been added to the existing diesel back-up solution to boost renewables and provide continuity of supply during disruptions or transitions from grid to island operation. South Africa is not alone when it comes to power shortages and outages and several other emerging economies in Africa, Asia, South America and other parts of the world face similar challenges. This type of microgrid solution that displaces traditional diesel stand-by generation could be applied at thousands of locations to improve electricity supply security.

The need for supply security is becoming ever more important to customers - in some geographies the threats to utility grid supply security have grown over recent times. This includes climate change driven threats, wind, floods and wildfires. In some countries utility network operators will switch off circuits as a wildfire prevention measure leaving customers off supply for potentially multiple days. In the California, USA, utility companies are increasingly having to use Public Safety Power Shutoffs (PSPS) which disconnect customers potentially for multiple days.

Smarter Grid Solutions (SGS) is working with customers in North American states on microgrid solutions including some relating to climate driven supply security. The following are typical examples.

• SGS is part of a consortium providing a PV/BESS microgrid solution that will allow a major fresh food processing facility in California to transition from a utility grid supply to an island microgrid condition that maintains the operation of critical process plant. The SGS microgrid control solution design also includes the ability to manage DER resources during island conditions, synchronise back to the grid and also black start the island microgrid if required. The microgrid will allow the process plant to have a planned transition to island conditions if the local facility wishes to move to a Public Safety Power Shutoff (PSPS) and cater for unplanned shutdowns of the utility grid connection e.g. due to a utility network fault condition.

• Hoopa Valley Tribe in a remote area of northern California is subject to outages because of public safety power shutoffs (PSPS) instituted by the utility company as a wildfire prevention measure. SGS provided its expertise to deliver a feasibility study looking at the use of a network of small solar and BESS based microgrids located in critical buildings on tribal property. The tribe is continuing to assess how they will implement the scheme.

Applications of microgrid technology to provide customer facilities with RES/BESS based standby supplies are becoming more common in addressing the need for improved electricity supply security. Scheme uptake is being driven particularly in regions with poorer utility supply security and also regions where climate change is now resulting in reduced supply security. SGS offers adaptable microgrid management software solutions with many features including generation and demand forecasting, island, non-island and grid to island transition DER management, island to grid synchronising and black start island supply restoration sequencing using our Strata Resilience product.