Distributed Energy Storage Systems Role in Reducing Wildfire Impacts on Smart Grids
By Hamidreza Nazaripouya, University of California, Riverside (UCR)-Winston Chung Global Energy Center (WCGEC)
DESS can contribute in preventive activities before wildfire events, in corrective and proactive responses during the course of wildfire events, and in restorative actions after wildfire events to reduce the impact of wildfires on electricity grids.
Over the last few years, wildfires have caused significant damages and interruptions to electricity grids. In 2019, around 940,000 customers across 38 counties in Northern and Central California lost power due to the risk of wildfire. 2019 Tasmanian bushfires in Melbourne, Australia led to blackouts, which affected 30,000 households and businesses. To this end, exploring solutions for providing continuous and reliable power supply for customers under wildfires seems imperative. Distributed Energy Storage Systems (DESS) can play a key role in improving smart grid reliability and resilience. Before wildfire events, and as part of preventive activities to reduce the wildfire impacts, DESS can contribute in forming decentralized energy systems, and promoting generation, storing and controlling energy locally and independent from the main grid. Smart operation of DESS enhances the flexibility of grids and increases the degree of freedom in power flow management. Therefore, during the course of wildfire events, DESS can facilitate the corrective and proactive responses to wildfire in terms of system islanding, optimal dispatching of power grids, and network reconfiguration. Finally, after wildfire events, DESS are able to minimize the impact of wildfires on customers, the economy, and the system, through assisting in restorative actions including system restoration (Black start) and load restoration. However, there are still some challenges due to characteristics and nature of some of the existing energy storage technologies, for example, flammability and explosion risk in batteries. This article explains the role of DESS to reduce wildfire impacts on smart grids and explore the corresponding challenges.
Before wildfire events, with the aim of reducing the potential impact of wildfires, a set of preventive actions is performed to increase grid resiliency in terms of robustness and resourcefulness. Grid integration of DESS can be considered as one of these preventive actions, if DESS are equipped with smart control mechanisms. The stored energy in DESS can provide virtual inertia for the grid, and thus increases the tolerance and robustness of the system to sudden wildfire-caused disturbances or power imbalance. DESS can release the stored energy effectively and in a timely manner, which will mitigate the disturbances and damp the potential instability in the system. In addition, DESS can enhance the resourcefulness for the customers who are at the high risk of power shut-off by utilities. The California Public Utilities Commission has recently directed $100M in energy storage incentives to wildfire-vulnerable households and critical service facilities to promote resourcefulness and energy self-supply. Therefore, DESS can positively contribute in forming decentralized energy systems, making energy system independent from the main grid, and thus minimizing the effects of main grid failures on electricity customers.
During the course of wildfire events, proactive responses such as network reconfiguration, system islanding, optimal load shedding, and/or optimal dispatching of power systems, can effectively minimize the impact of wildfires. The common ground for all the above corrective actions is to solve security-constrained optimal power flow, which aims to optimize the operation of controllable resources and equipment by modeling the network flexibility and system constraints. Incorporation of DESS into smart grid platforms adds new control knobs and relaxes some of the constraints in the system. DESS increase the system flexibility and extend the solution space by: 1) facilitating the supply-demand matching, 2) making renewable resources dispatchable, 3) increasing the ramp range and better following the variation in net loads, 4) providing reserve capacity, and 5) enhancing power flow control.
After wildfire events, the most crucial action is to effectively and quickly bring the system back to the normal operation and restore systems and loads. Methods for optimal restoration aim to minimize the restoration time, minimize active power loss, and maximize the served load. During power system restoration process due to the system vulnerability, insufficient regulation capability, and limited generation capacity, the restoration process is performed sequentially and gradually over time, which is normally slow. The flexibility in charging and discharging of DESS can help with constantly maintaining the supply-demand balance over the restoration process and accelerate the system recovery. Moreover, in power delivery process, DESS can provide local power, and reduce power losses over lines. Since DESS are distributed across the system, the accessibility to resources after wildfire events, and consequently the amount of served load will increase. In addition, DESS can act as black-start resources, or their stored energy can be used to start non-black-start generators, which again lead to more load restoration. DESSs can be utilized as power loads in the process of energizing unloaded transmission lines, which relieves the possible overvoltage at ends of transmission lines and self-excitation problems in black-start generators. Also, at the early stage and during the restoration process the distribution of power flows may be quite uneven. Therefore, proper DESS management could optimize the distribution of power flows.
In spite of positive contributions of DESS in reducing wildfires impacts on electricity grids, still deployment of energy storage technologies includes some concerns. The explosion and fire at 2MW battery storage facility at the McMicken substation in the west of Phoenix has raised concerns about the challenges and risks of deploying battery storage technologies due to their flammability and explosive characteristics. Also, in fuel cells, all the suitable fuels used in cells easily catch fire and thus pose a significant fire and explosion hazards. National Fire Protection Association (NFPA) has released NFPA 855, standard for deployment of stationary energy storage systems, which covers the fire and life safety hazards associated with energy storage systems. NFPA 855 should be followed to ensure safe installation and operation of different energy storage technologies, especially in wildfire-related applications. Limited energy capacity in some energy storage technologies, such as battery storage, flow battery and flywheel, is another concern. To this end, the investment and research on long-duration energy storage seems imperative.
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Hamidreza Nazaripouya at the University of California, Riverside (UCR). He obtained his Ph.D. degree from the University of California, Los Angeles (UCLA). He received the M.S. degree in power systems from Louisiana State University in 2013, and the M.S. degree in power electronics from the Sharif University of Technology in 2010. His research on integration and control of distributed renewable energy resources and battery storage systems has led to multiple publications and patents in the field. His patented technology won the NSF grant award with him as the entrepreneurial lead to investigate the commercialization of the technology. He is the Lead Primary Investigator (PI) of Smart Battery research project and Co–PI of several energy-related projects at UCR. Dr. Nazaripouya is an experienced power system engineer with industry background. In particular, he has worked for Entergy Corporation, owner and operator of power plants with approximately 30,000 MW of electric generating capacity. He has conducted several projects for utility companies during his career. His research interests include control and integration of DERs, application of power electronics in power system, smartgrid technologies, electric vehicles and battery energy storage systems.
Dr. Nazaripouya has received several honors and awards, including IEEE SFV Section Rookie of the Year Award, IEEE IAS and PES Presentation Awards, and the UC Dissertation-Year Fellowship Award.
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