Accelerating Load Pickup Using Storage Systems in Power System Restoration

During power system restoration, it is critical to maintain system frequency to avoid any further outage or cascading events. Load pickup is one of the most important tasks that require generation-load balance for a stable system frequency. In current industry practice, small loads are served incrementally to avoid frequency dip that causes instability in system. However, slow load pickup may prolong the system restoration process. As the fast response energy resources, storage system, including batteries and electric vehicles can expedite load pickup by compensating the imbalance between generation and load. The objective of this thesis was to develop a restoration strategy for reliable load pickup and faster restoration using energy storage in transmission and distribution systems. Frequency response of conventional generators for sudden load pickup by the system was modeled and simulated. Optimization problem of finding load pickup sequence to maximize restored energy was formulated as a Mixed Integer Linear Programming (MILP) problem. Transmission and distribution restoration optimization model was designed to increase the efficiency of the system restoration procedure. Case studies with different storage capacities were tested to evaluate benefit of storage systems in power system restoration. Simulation results suggested that energy storage is able to increase total restored energy and reduce load restoration time after a blackout. Simulation results on 100-feeder test system demonstrated the benefit of using MILPxii based restoration strategy and the benefit from electric vehicles to restore more energy in given restoration time. The proposed restoration strategy has great potential to facilitate system operators to achieve optimized system restoration plans. This study provides incentives to deploy a large amount of PHEVs to improve system resiliency

Optimal distribution system restoration using PHEVs

Power outages cost billions of dollars every year and jeopardise the lives of hospital patients. Traditionally, power distribution system takes a long time to recover after a major blackout, due to its top-down operation strategy. New technologies in modern distribution systems bring opportunities and challenges to distribution system restoration. As fast response energy resources, plug-in hybrid electric vehicles (PHEVs) can accelerate the load pickup by compensating the imbalance between available generation and distribution system load. This study provides a bottom-up restoration strategy to use PHEVs for reliable load pickup and faster restoration process. The optimisation problem of finding load pickup sequence to maximise restored energy is formulated as a mixed integer linear programming (MILP) problem. Moreover, the coordination between transmission and distribution restoration is developed to efficiently restore the entire system back to normal operating conditions. Simulation results on one 100-feeder test system demonstrate the efficiency of MILP-based restoration strategy and the benefit from PHEVs to restore more energy in given restoration time. The proposed restoration strategy has great potential to facilitate system operators to achieve efficient system restoration plans. It also provides incentives to deploy a large amount of PHEVs to improve system resiliency