Assessment and Enhancement of Small Signal Stability of a Renewable-Energy-Based Electricity Distribution System

Market deregulation and environmental concerns of the power sector have encouraged renewable energy integration in the form of distributed generation, mainly in distribution systems. With integration of different generators and controllers, distribution systems are facing different types of stability issues which were not a concern in the past. This paper examines the small signal stability performance of a renewable-energy-based distribution system. The system, which consists of static and dynamic loads, is supplied by synchronous, induction, and static generators. The existence and nature of oscillatory modes are systematically investigated. A control methodology of using existing capacitor banks to support small signal stability of a distribution system is proposed. A controllability-based index is used to identify the controllable capacitor bank. An observability index has been used to design the additional controller for damping control. The effectiveness of capacitor controller is illustrated by using both eigenvalue and time-domain analyses.