Enhanced Automatic Generation Control (E-AGC) for Electric Power Systems with Large Intermittent Renewable Energy Sources

Abstract

This paper is motivated by the need to enhance today's Automatic Generation Control (AGC) for ensuring high quality frequency response in the changing electric power systems. Renewable energy sources, if not controlled carefully, create persistent fast and often large oscillations in their electric power outputs. A sufficiently detailed dynamical model of the interconnected system which captures effects of fast nonlinear disturbances created by the renewable energy resources is derived for the first time. Consequently, the real power flow interarea oscillations, and the resulting frequency deviations are modeled. The modeling is multi-layered, and the dynamics of each layer (component level (generator); control area (control balancing authority), and the interconnected system) is expressed in terms of internal states and the interaction variables (IntV) between the layers and within the layers. E-AGC is then derived using this model to show how these interarea oscillations can be canceled. Simulation studies are carried out on a 5-bus system.

Unified value-based feedback, optimization and risk management in complex electric energy systems

“…The dynamics of the interaction variable z i = [E i , p i ] , where p i =Ė i captures the dynamics of internal energy conversion independent of the type of energy conversion. The concept of interaction variables was first pursued in [39] and has appeared in several other works later on [3,84,[96][97][98]. It is however for the first time in [2] that it has been possible to capture both real and reactive power dynamical interactions.…”