Robustness of distributed averaging control in power systems: Time delays & dynamic communication topology

Abstract

Distributed averaging-based integral (DAI) controllers are becoming increasingly popular in power system applications. The literature has thus far primarily focused on disturbance rejection, steady-state optimality and adaption to complex physical system models without considering uncertainties on the cyber and communication layer nor their effect on robustness and performance. In this paper, we derive sufficient delay-dependent conditions for robust stability of a secondary-frequency-DAIcontrolled power system with respect to heterogeneous communication delays, link failures and packet losses. Our analysis takes into account both constant as well as fast-varying delays, and it is based on a common strictly decreasing LyapunovKrasovskii functional. The conditions illustrate an inherent trade-off between robustness and performance of DAI controllers. The effectiveness and tightness of our stability certificates are illustrated via a numerical example based on Kundur's fourmachine-two-area test system.

Exponential convergence under distributed averaging integral frequency control

“…In this light, it is useful to consider strictly decreasing energy functions (Malisoff and Mazenc, 2009). Zhao et al (2015) make a first attempt to arrive at one, and their effort is expanded upon by Schiffer et al (2017) in the context of time-delayed communication. Bearing this in mind, we propose a construction of a new strict Lyapunov function for the purpose of explicitly quantifying the exponential convergence of power networks under distributed averaging integral control and then study the performance of this control in the presence of communication disruptions.…”

“…The contribution of this paper is primarily theoretical: existing approaches to the problem of optimal frequency control have mostly relied on non-strictly decreasing energy -or Lyapunov functions, using LaSalle's invariance principle and related results to guarantee convergence to an invariant manifold on which the Lyapunov function's derivative vanishes (see Schiffer et al, 2017;Vu and Turitsyn, 2017 for exceptions). Since this does not lead to strong results on convergence, we design a strictly decreasing Lyapunov function that does prove exponential convergence to the optimal synchronous solution.…”

Steady state evaluation of distributed secondary frequency control strategies for microgrids in the presence of clock drifts

“…Furthermore, the communication layer can be designed such that the controllers are resilient to communication path failures. In [12], conditions for robust non-linear stability of MGs operated with a distributed averaging integral controller under fast-varying time-delays and switching communication topology are derived. Furthermore, various secondary frequency control policies are compared in [13].…”

Multilevel Power-Imbalance Allocation Control for Secondary Frequency Control of Power Systems

“…In practice, the voltage can be well controlled by Automatic Voltage Regulator (AVR). This model and the ones with linearized sine function are widely studied, e.g., [7], [8], [30], [23], [26], [43], [16], in which the frequency dependent nodes are usually used to model the renewable power inverters. The system (1) synchronizes at an equilibrium state, called synchronous state defined as follows [6].…”

“…Therefore, a form of distributed control is proposed for control of power systems, which are either based on passivity method [20], [37], [17], [30], [28], [26], [27] or primal-dual method [42], [16], [43], [34]. In distributed control of a power system, a number of controllers try to achieve the control objectives of the entire network via coordination and cooperation.…”