Consensus-based distributed secondary frequency control schemes have the potential to simultaneously ensure real-time frequency restoration and economic dispatch in future power systems with large shares of renewable energy sources. Yet, due to their distributed nature these control schemes critically depend on communication between units and, thus, robustness with respect to communication uncertainties is crucial for their reliable operation. Furthermore, when applied in bulk power systems the control design and analysis should take higher-order turbine-governor dynamics of the generation units explicitly into account. Both aspects have not been addressed jointly in the existing literature. Motivated by this, we derive conditions for robust stability of a consensus-based distributed frequency control scheme applied to a power system model with second-order turbine-governor dynamics in the presence of heterogeneous time-varying communication delays and dynamic communication topology. The result is established by a novel coordinate transformation and reduction to eliminate the invariant subspace in the closed-loop dynamics and by constructing a strict common Lyapunov-Krasovskii functional.

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Consensus algorithms are promising control schemes for secondary control tasks in microgrids. Since consensus algorithms are distributed protocols, communication efforts and time delays are significant factors for the control design and performance. Moreover, both the electrical and the communication layer in a microgrid are continuously exposed to exogenous disturbances. Motivated by this, we derive a synthesis for a consensus-based secondary frequency controller that guarantees robustness with respect to time-varying delays and in addition provides the option to trade off L2 disturbance attenuation against the number of required communication links. The efficacy of the proposed approach is illustrated via simulations based on the CIGRE benchmark medium voltage distribution network.

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