Panel Session: Protection Systems on a Distributed Energy Resources (DERs)-Rich Electricity Network – The Challenges they are Facing and A Roadmap for the Future (slides)

The National Grid is facing a crucial task for leading the effort of net-zero by 2030. To meet the daunting target, greenhouse gas emissions from fossil fuel powered plants for generation, transportation must be considerably reduced. In the field of electricity generation, this goal can be achieved through the integration of large-scale and small-scale renewable energy resources. The Distributed Energy Resources (DERs) would contribute heavily in the decarbonization efforts.

The high penetration of DER rich resources poses certain challenges to the power distribution network. Protection systems were designed keeping in mind the uni-directional flow of power from generation to load (consumer). DERs create the task of managing generation resources in-situ with the loads that can hamper protection, operation, and other challenges. Currently, utilities do not have control over customer installed DERs, thus challenges associated with relay co-ordination and settings pose a paramount risk to grid reliability. The current limiting control schemes of inverter-based resources (IBRs) prevent injection of unregulated fault current into the grid. For relays using time current curve (TCC) to detect faults fails to detect such faults. If the faults are not detected in a timely manner they can cause detrimental damage, fire resulting in large-scale grid shut down. Anti-islanding protection schemes are designed to detect disturbances in the grid and shut down DER resources within seconds to prevent feeding power back to the grid. However, with DERs participating in voltage control, frequency regulation etc., it hampers the inverter protection settings. This can be a threat to the safety of the crew trying to restore outages.

Some of the challenges can be mitigated through the integration of high-speed communication networks, high powered computational platforms etc. Energy Management Systems (EMS) use smart measuring and sensing performs real-time operations that co-ordinate the operating state of the grid, preventing it from blackouts, device failures and other challenges. These enhanced capabilities will effectively improve the observability of the grid. However, this creates several vulnerabilities related to cybersecurity. For the development of a smart and connected grid it is imperative to develop and enhance cybersecurity protection to make the grid reliable and safe.

There is a pressing need for development of protection schemes that ensure fast and reliable operations. Utilizing advanced signal processing techniques, distributed sensing and other existing or emerging capabilities, the utilities would need to improve the protection systems in a cost-affordable manner to enable effective operation of the DERs.