  This paper aims to investigate the risk identification problem of power
transmission system that is integrated with renewable energy sources. In
practice, the fluctuation of power generation from renewable energy sources can
lead to severe consequences to power transmission network. By treating the
fluctuation of power generation as the control input, the risk identification
problem is formulated with the aid of optimal control theory. Thus, a control
approach is developed to identify the fluctuation of power generation that
results in the worst-case cascading failures of power systems. Theoretical
analysis is also conducted to obtain the necessary condition for the worst
fluctuations of power generation. Finally, numerical simulations are
implemented on IEEE 9 Bus System to demonstrate the effectiveness of the
proposed approach.
