Fragility of Decentralized Load-Side Frequency Control in Stochastic Environment
For power system operators, it reveals a fragility in existing decentralized frequency control methods when integrating renewable energy.
This paper shows that decentralized load-side frequency control algorithms become stochastically unstable under small parametric uncertainty in bus voltages, with the critical variance decreasing as controllable load costs or renewable penetration increase.
In this paper, we demonstrate the fragility of decentralized load-side frequency algorithms proposed in [1] against stochastic parametric uncertainty in power network model. The stochastic parametric uncertainty is motivated through the presence of renewable energy resources in power system model. We show that relatively small variance value of the parametric uncertainty affecting the system bus voltages cause the decentralized load-side frequency regulation algorithm to become stochastically unstable. The critical variance value of the stochastic bus voltages above which the decentralized control algorithm become mean square unstable is computed using an analytical framework developed in [2], [3]. Furthermore, the critical variance value is shown to decrease with the increase in the cost of the controllable loads and with the increase in penetration of renewable energy resources. Finally, simulation results on IEEE 68 bus system are presented to verify the main findings of the paper.