ABSTRACT
Effective coordination of Distributed Energy Resources (DERs) in power systems via control strategies mitigates the frequency fluctuations stemming from stochastic renewables and uncertain demand. Recently, open communication networks are used to deploy Load Frequency Control (LFC) strategies to overcome the lack of dedicated communication infrastructures and the ubiquity of DERs system. However, open networks are exposed to communication degradation and can reduce the LFC performance. This work investigates the real-time performance and reliability of the integrated DER system and open communication networks, i.e. the cyber-physical microgrid system, with reference to LFC against communication degradation. In particular, LFC is provided by a discrete PID controller tuned via particle swarm optimization. The cyber-physical microgrid system is implemented on a real-time platform simulating various MAC protocols and open-communication-network architectures, developed in the Truetime simulator. The impact of communication degradation on LFC performance is assessed. Simulation results demonstrate that transmission delays and packet dropouts jeopardize the ability of cyber-physical microgrid systems to maintain system frequency deviations within tolerance bounds. In particular, the use of Ethernet ensures higher reliability as compared to 802.11 b/g. Moreover, the impact of interfering traffic and of the percentage of used bandwidth on the LFC performance reduction is evaluated. The optimized PID controller is able to compensate for communication degradation and uncertainty of the microgrid, and ensures robust LFC against unknown network configurations.
