Eduardo Mojica-Nava

Dynamic Population Games for Optimal Dispatch on Hierarchical Microgrid Control

In the path to the future implementation of the smart grid, microgrids are presented as a cornerstone. An efficient and optimal microgrid operation is paramount. In this paper, we present a hierarchical microgrid management system using task sharing and an evolutionary game theory based dispatch strategy as a coordination algorithm to integrate the three main control levels needed for microgrid operation, which can be considered as a distributed intelligent system. The proposed algorithm shares the total load demanded into the distributed generators efficiently, while the microgrid utility is maximized dynamically, increasing the system reliability. Some simulation results are presented to illustrate the effectiveness of the dynamic performance of the proposed approach compared with a traditional hierarchical algorithm.

A polynomial approach for stability analysis of switched systems

A polynomial approach to deal with the stability analysis of switched non-linear systems under arbitrary switching using dissipation inequalities is presented. It is shown that a representation of the original switched problem into a continuous polynomial system allows us to use dissipation inequalities for the stability analysis of polynomial systems. With this method and from a theoretical point of view, we provide an alternative way to search for a common Lyapunov function for switched non-linear systems.

A survey on Cyber Physical Energy Systems and their applications on smart grids

An important challenge for future energy systems is a new modeling methodology that integrates the cyber and physical components. This model must include the impact of communication networks and further cyber components, besides the relevant information of the physical system, in terms of efficiency, sustainability, reliability, security, and stability. The Cyber Physical Energy Systems (CPES) concept is presented as an interesting alternative to address this issue and its main features are identified. The main CPES research areas are identified as: modelling energy systems, energy efficiency, energy resource management, and energy control. In this work, the advantages of the CPES approach are shown in order to address current challenges in future energy systems. Smart grids, based on microgrids and distributed generation concepts, are identified as an interesting application of the CPES. A new proposal for modeling smart grids based on the CPES approach is introduced.

The Role of Population Games and Evolutionary Dynamics in Distributed Control Systems: The Advantages of Evolutionary Game Theory

Recently, there has been an increasing interest in the control community in studying large-scale distributed systems. Several techniques have been developed to address the main challenges for these systems, such as the amount of information needed to guarantee the proper operation of the system, the economic costs associated with the required communication structure, and the high computational burden of solving for the control inputs for largescale systems.

Time-delay effect on load frequency control for microgrids

The time-delay effect on load frequency control (LFC) for power smart grids systems based on microgrids (MGs) is analyzed. A new cyber-physical modeling approach is used to identify system signals that are vulnerable to communication constraints. An analytic approach based on the Rekasius substitution and sum of squares decomposition is proposed to find the time-delay stability margin of LFC in microgrids. The cyber physical modeling and time-delay margin analysis approaches are applied to a microgrid example based on a distributed diesel generator and a photo-voltaic generator. In addition, the impact of time-delays for these class of systems is shown in simulation. The proposed approach can be used to analyze other cybernetic constraints in smart grid power systems and the methodology used to find delay stability margin can be extended to power systems of larger scale, as interconnected microgrids.

Design of mechanisms for demand response programs

We prove the inefficiency (in the sense of Pareto) of the electricity system, as well as its resemblance with the tragedy of the commons. Also, we present a mechanism intended to achieve efficiency in the electricity consumption by means of economic incentives. The proposed incentives might be seen as an indirect revelation mechanism, in which users do not have to reveal private information about their preferences. Instead, a particular incentive is calculated for each user, based solely on its relative consumption. We conclude that the success of the proposed mechanism requires subsidies from external institutions, at least during the transition between an inefficient outcome and the efficient equilibrium.

Population Games Methods for Distributed Control of Microgrids

We illustrate the potential of applying population games in two key related problems in microgrids management: 1) economic dispatch of active and reactive power; and 2) demand response. For the dynamic economic dispatch problem, we present a hierarchical microgrid energy management algorithm able to dispatch active and reactive power dynamically. In the second case, we use an opinion dynamics model, including the market in which the network agents interact. Opinion dynamics considers individuals who shape their beliefs based on information they receive from a subset of the society and offers tools to analyze the outcome of collective decision processes, which apparently can be considered arbitrary. We propose an opinion dynamics model including some desired characteristics, such as prominent agents and environmental incentives.

Optimal Control of Switched Systems: A Polynomial Approach

Abstract A polynomial approach to solve the optimal control problem of switched systems is presented. It is shown that the representation of the original switched problem into a continuous polynomial systems allow us to use the method of moments. With this method and from a theoretical point of view, we provide necessary and sufficient conditions for the existence of minimizer by using particular features of the minimizer of its relaxed, convex formulation. Even in the absence of classical minimizers of the switched system, the solution of its relaxed formulation provide minimizers.

CPS: market analysis of attacks against demand response in the smart grid

Demand response systems assume an electricity retail-market with strategic electricity consuming agents. The goal in these systems is to design load shaping mechanisms to achieve efficiency of resources and customer satisfaction. Recent research efforts have studied the impact of integrity attacks in simplified versions of the demand response problem, where neither the load consuming agents nor the adversary are strategic. In this paper, we study the impact of integrity attacks considering strategic players (a social planner or a consumer) and a strategic attacker. We identify two types of attackers: (1) a malicious attacker who wants to damage the equipment in the power grid by producing sudden overloads, and (2) a selfish attacker that wants to defraud the system by compromising and then manipulating control (load shaping) signals. We then explore the resiliency of two different demand response systems to these fraudsters and malicious attackers. Our results provide guidelines for system operators deciding which type of demand-response system they want to implement, how to secure them, and directions for detecting these attacks.

Delay and sampling independence of a consensus algorithm and its application to smart grid privacy

The consensus algorithm can represent many problems in cooperative behavior, and has been widely used in engineering and social sciences. In this work, we prove that the consensus model where the information that each agent receives from its neighbors has time-varying asynchronous delays and sampling, converges to an agreement independent of these communication constraints. This property is useful in the context of “data minimization,” which is one of the principles for privacy. As a practical example, we show how the independence of sampling rate can be used for microgrids with a consensus-based secondary control scheme where participants have incentives to share their states to ensure frequency synchronization, while at the same time minimizing the amount of data shared to preserve their privacy. We then propose two data sharing algorithms: 1) periodic sampling, and 2) discretionary sampling, and study their privacy as well as their performance. We show that even when a discretionary sampling scheme “lies” to their neighbors in order to preserve their privacy, the consensus algorithm performs almost as well as with periodic sampling.