We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

Random graphs

MATPOWER is an open-source Matlab-based power system simulation package that provides a high-level set of power flow, optimal power flow (OPF), and other tools targeted toward researchers, educators, and students. The OPF architecture is designed to be extensible, making it easy to add user-defined variables, costs, and constraints to the standard OPF problem. This paper presents the details of the network modeling and problem formulations used by MATPOWER, including its extensible OPF architecture. This structure is used internally to implement several extensions to the standard OPF problem, including piece-wise linear cost functions, dispatchable loads, generator capability curves, and branch angle difference limits. Simulation results are presented for a number of test cases comparing the performance of several available OPF solvers and demonstrating MATPOWER's ability to solve large-scale AC and DC OPF problems.

/pdf/matpower-steady-state-operations-planning-and-analysis-tools-1v40ihity5.pdf

MATPOWER: Steady-State Operations, Planning, and Analysis Tools for Power Systems Research and Education

The Smart Grid, regarded as the next generation power grid, uses two-way flows of electricity and information to create a widely distributed automated energy delivery network. In this article, we survey the literature till 2011 on the enabling technologies for the Smart Grid. We explore three major systems, namely the smart infrastructure system, the smart management system, and the smart protection system. We also propose possible future directions in each system. colorred{Specifically, for the smart infrastructure system, we explore the smart energy subsystem, the smart information subsystem, and the smart communication subsystem.} For the smart management system, we explore various management objectives, such as improving energy efficiency, profiling demand, maximizing utility, reducing cost, and controlling emission. We also explore various management methods to achieve these objectives. For the smart protection system, we explore various failure protection mechanisms which improve the reliability of the Smart Grid, and explore the security and privacy issues in the Smart Grid.

/pdf/smart-grid-the-new-and-improved-power-grid-a-survey-4jypbbgv3j.pdf

Smart Grid — The New and Improved Power Grid: A Survey

The increasing interest in integrating intermittent renewable energy sources into microgrids presents major challenges from the viewpoints of reliable operation and control. In this paper, the major issues and challenges in microgrid control are discussed, and a review of state-of-the-art control strategies and trends is presented; a general overview of the main control principles (e.g., droop control, model predictive control, multi-agent systems) is also included. The paper classifies microgrid control strategies into three levels: primary, secondary, and tertiary, where primary and secondary levels are associated with the operation of the microgrid itself, and tertiary level pertains to the coordinated operation of the microgrid and the host grid. Each control level is discussed in detail in view of the relevant existing technical literature.

Trends in Microgrid Control

Smart Grid - The New and Improved Power Grid:

The restructuring of the electric power grid has created new control and monitoring requirements for which classical technologies may be inadequate. The most obvious way of building such systems, using TCP connections to link monitoring systems with data sources, gives poor scalability and exhibits instability precisely when information is most urgently required. Astrolabe, Bimodal Multicast, and Gravitational Gossip, technologies of our own design, seek to overcome these problems using what are called "epidemic" communication protocols. This paper evaluates a hypothetical power monitoring scenario involving the New York State grid, and concludes that the technology is well matched to the need.

/pdf/dcovercoming-communications-challenges-in-software-for-1tcox7enz4.pdf

dcOvercoming Communications Challenges in Software for Monitoring and Controlling Power Systems

Impacts of malicious data data attack on the real-time electricity market are studied. It is assumed that an adversary has access to a limitted number of meters and has the ability to construct data attack based on what it observes. Different observation models are considered. A geometric framework is introduced based on which upper and lower bounds on the optimal data attack are obtained and evaluated in simulations.

/pdf/impacts-of-malicious-data-on-real-time-price-of-electricity-gh4x76ysbj.pdf

Impacts of Malicious Data on Real-Time Price of Electricity Market Operations

Probabilistic reliability criteria, such as LOLP, LOLE, EENS etc., have been used extensively for generation expansion planning throughout the world. Typically, only deterministic reliability criteria, such as (N-1) or (N-2) contingencies, have been used for grid expansion planning until now. The main reason is the difficulty in determining the optimum design of a grid expansion plan using probabilistic reliability criteria and in developing the appropriate mathematical model that incorporates the chosen reliability criterion for the transmission system. Optimum design in grid expansion planning is still an important element of overall electric power system planning in deregulated electricity markets. One of the potential improvements in generation and grid expansion planning comes from the use of a more realistic reliability level as a criterion to constrain the form of the optimum expansion problem. A methodology is proposed that uses a probabilistic reliability criterion to determine an optimum plan for transmission system expansion using a criterion that minimises the expected cost, which includes both construction and outage costs, using a probabilistic reliability criterion loss of load expectation R
LOLE. The optimum value of the reliability criterion R
LOLE
 *
 is determined at the minimum value of the combined total of the cost of constructing new transmission and the customer outage cost associated with supply interruptions. The characteristics and effectiveness of this methodology are illustrated by a case study using a 21-busbar test system

Probabilistic reliability criterion for planning transmission system expansions

Earlier research has shown that adding wind generation to a network can lower the total annual operating cost by displacing conventional generation. At the same time, the variability of wind generation and the need for higher levels of reserve generating capacity to maintain reliability standards impose additional costs on the system that should not be ignored. The important implication for regulators is that the capacity payments ["missing money"] for each MW of peak system load are now much higher. Hence, the economic benefits of reducing the peak system load using storage or controllable demand will be higher with high penetrations of wind generation. These potential benefits are illustrated in a case study using a test network and a security constrained Optimal Power Flow (OPF) with endogenous reserves (SuperOPF). The results show that the benefits are very sensitive to 1) how much of the inherent variability of wind generation is mitigated, and 2) how the missing money is determined (e.g. comparing regulation with deregulation).

/pdf/the-hidden-system-costs-of-wind-generation-in-a-deregulated-1esrciwm52.pdf

The Hidden System Costs of Wind Generation in a Deregulated Electricity Market

Several researchers have suggested characterising a power system voltage collapse using the singularity of the Jacobian of the network descripter load-flow equations. It has been proposed to use the minimum singular value of the Jacobian as a security index for monitoring how closely a power system is operating to a voltage instability. However, a singular value decomposition (SVD) computation is an iterative process with a number of arithmetic operations proportional to the cubic power of the matrix size. State-of-the-art SVD computation schemes using large arrays of parallel processors that improve the computation speed linearly and quadratically are discussed. A comparison is made between the computation speed and the number of arithmetic units required for various parallel architecture schemes as well as with the traditional serial computer. >

Robert J. Thomas

Papers

dcOvercoming Communications Challenges in Software for Monitoring and Controlling Power Systems

Impacts of Malicious Data on Real-Time Price of Electricity Market Operations

Probabilistic reliability criterion for planning transmission system expansions

The Hidden System Costs of Wind Generation in a Deregulated Electricity Market

Towards a computationally feasible on-line voltage instability index