350,861 research outputs found
An Application of Joint Spectral Radius in Power Control Problem for Wireless Communications
Resource management, including power control, is one of the most essential
functionalities of any wireless telecommunication system. Various transmitter
power-control methods have been developed to deliver a desired quality of
service in wireless networks. We consider two of these methods: Distributed
Power Control and Distributed Balancing Algorithm schemes. We use the concept
of joint spectral radius to come up with conditions for convergence of the
transmitted power in these two schemes when the gains on all the communications
links are assumed to vary at each time-step.Comment: 4 page
Joint Frequency Regulation and Economic Dispatch Using Limited Communication
We study the performance of a decentralized integral control scheme for joint
power grid frequency regulation and economic dispatch. We show that by properly
designing the controller gains, after a power flow perturbation, the control
achieves near-optimal economic dispatch while recovering the nominal frequency,
without requiring any communication. We quantify the gap between the
controllable power generation cost under the decentralized control scheme and
the optimal cost, based on the DC power flow model. Moreover, we study the
tradeoff between the cost and the convergence time, by adjusting parameters of
the control scheme.
Communication between generators reduces the convergence time. We identify
key communication links whose failures have more significant impacts on the
performance of a distributed power grid control scheme that requires
information exchange between neighbors
Distributed Frequency Control in Power Grids Under Limited Communication
In this paper, we analyze the impact of communication failures on the
performance of optimal distributed frequency control. We consider a
consensus-based control scheme, and show that it does not converge to the
optimal solution when the communication network is disconnected. We propose a
new control scheme that uses the dynamics of power grid to replicate the
information not received from the communication network, and prove that it
achieves the optimal solution under any single communication link failure. In
addition, we show that this control improves cost under multiple communication
link failures. Next, we analyze the impact of discrete-time communication on
the performance of distributed frequency control. In particular, we will show
that the convergence time increases as the time interval between two messages
increases. We propose a new algorithm that uses the dynamics of the power grid,
and show through simulation that it improves the convergence time of the
control scheme significantly.Comment: 8 pages, 7 figure
Pseudo-gradient Based Local Voltage Control in Distribution Networks
Voltage regulation is critical for power grids. However, it has become a much
more challenging problem as distributed energy resources (DERs) such as
photovoltaic and wind generators are increasingly deployed, causing rapid
voltage fluctuations beyond what can be handled by the traditional voltage
regulation methods. In this paper, motivated by two previously proposed
inverter-based local volt/var control algorithms, we propose a pseudo-gradient
based voltage control algorithm for the distribution network that does not
constrain the allowable control functions and has low implementation
complexity. We characterize the convergence of the proposed voltage control
scheme, and compare it against the two previous algorithms in terms of the
convergence condition as well as the convergence rate
A distributed accelerated gradient algorithm for distributed model predictive control of a hydro power valley
A distributed model predictive control (DMPC) approach based on distributed
optimization is applied to the power reference tracking problem of a hydro
power valley (HPV) system. The applied optimization algorithm is based on
accelerated gradient methods and achieves a convergence rate of O(1/k^2), where
k is the iteration number. Major challenges in the control of the HPV include a
nonlinear and large-scale model, nonsmoothness in the power-production
functions, and a globally coupled cost function that prevents distributed
schemes to be applied directly. We propose a linearization and approximation
approach that accommodates the proposed the DMPC framework and provides very
similar performance compared to a centralized solution in simulations. The
provided numerical studies also suggest that for the sparsely interconnected
system at hand, the distributed algorithm we propose is faster than a
centralized state-of-the-art solver such as CPLEX
Robust Decentralized Secondary Frequency Control in Power Systems: Merits and Trade-Offs
Frequency restoration in power systems is conventionally performed by
broadcasting a centralized signal to local controllers. As a result of the
energy transition, technological advances, and the scientific interest in
distributed control and optimization methods, a plethora of distributed
frequency control strategies have been proposed recently that rely on
communication amongst local controllers.
In this paper we propose a fully decentralized leaky integral controller for
frequency restoration that is derived from a classic lag element. We study
steady-state, asymptotic optimality, nominal stability, input-to-state
stability, noise rejection, transient performance, and robustness properties of
this controller in closed loop with a nonlinear and multivariable power system
model. We demonstrate that the leaky integral controller can strike an
acceptable trade-off between performance and robustness as well as between
asymptotic disturbance rejection and transient convergence rate by tuning its
DC gain and time constant. We compare our findings to conventional
decentralized integral control and distributed-averaging-based integral control
in theory and simulations
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