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:

This paper presents our study in designing a 700 acre low-energy community on the Island of Hawaii. This study was an interdisciplinary collaboration among engineering, architecture, landscape architecture and business management. We took an integrated approach, which encompasses reducing energy demand, optimizing on-site renewable energy generation, implementing an efficient energy distribution system as well as effective energy management, and conserving natural resources. Technologies and their system integration were modeled and analyzed including solar photovoltaics, battery and compressed air energy storage, plug-in hybrid electric vehicles, demand response, microgrid, energy aggregator, passive and deep source cooling, microclimate and alternative landscaping. Various business models were developed. We showed that, with careful planning, it is feasible for a low energy or net zero energy community to become environmentally friendly and economically profitable at the same time. This community will benefit its residents, developers, investors, the utility company and the rest of the world.

/pdf/an-integrated-design-approach-for-sustainable-community-4b9czb2f9b.pdf

An Integrated Design Approach for Sustainable Community Development

Testing the Effects of Price Responsive Demand on Pay-as-Offered and Soft-Cap Electricity Auctions.

The distribution of stochastic generation from renewables across different geographical locations can, in certain cases, help to mitigate the inherent variability in output. This variability of generation from renewables may 1) increase the operating costs of the conventional generators used to follow the net load not supplied by stochastic capacity and 2) increase the amount of reserve conventional generating capacity needed to maintain Operating Reliability. In this scenario, customers have lower wholesale prices, due to reductions in the total annual generation from fossil fuels, while generators face higher operating costs for conventional generators caused by additional ramping that partly offset the customer benefits. However, the lower wholesale prices ($/MWh) imply lower annual earnings for conventional generators that lead to higher amounts of missing money ($/MW) needed to maintain the financial adequacy of installed generating units. The objective of this paper is to determine how variability from a stochastic generation resource affects the optimal hour-to-hour dispatch of generating units and the corresponding operating costs and wholesale prices. The results show that the inclusion of ramping costs for conventional generation affect the amount of energy dispatched from the stochastic generator, and the total costs composition observed in the system. The Cornell SuperOPF1 is used to illustrate how the operating costs and wholesale prices can be determined for a reliable network (the amount of conventional generating capacity needed to maintain Operating Reliability is determined endogenously). The results in this paper use a typical daily pattern of load and capture the cost of ramping by including additions to the operating costs of the generating units associated with the hour-to-hour changes in their optimal dispatch. The calculations for determining endogenous up and down reserves are included, and the wind generation cost is assumed to be zero. Additionally, the maximum and minimum available capacities for all hours in the day are constrained to the optimal capacities for the hours with the highest and the lowest loads. Different scenarios are evaluated for a given hourly realization of wind speeds using specified amounts of installed wind capacity with and without ramping costs. The analysis also evaluates the effects of eliminating network constraints, as well as the elimination of wind variability by accounting for the effects of spatial aggregation of different wind locations.

Geographical averaging and ancillary services for stochastic power generation

Cascading failure in power grids has long been recognized as a sever security threat to national economy and society, which happens infrequent but can cause severe consequences. The causes of cascading phenomena can be extremely complicated due to the many different and interactive mechanisms such as transmission overloads, protection equipment failures, transient instability, voltage collapse, etc. In the literature a number of vulnerability measures to cascading failures have been proposed to identify the most critical components in the grid and evaluate the damages caused by the removal of such recognized components from the grid. In this paper we propose a novel power grid vulnerability measure called the minimum safety time after 1 line trip, defined based on the stochastic cascading failure model[1]. We compare its performance with several other vulnerability measures through a set of statistical analysis.

http://www.apsipa.org/proceedings_2012/papers/275.pdf

Power grid vulnerability measures to cascading overload failures

The abuse of market power is a potentially serious problem for market designers. Few indices, if any, exist to measure the potential for market power in real time. In this regard, Murillo-Sanchez et al. derived an expression for a dispatch-to-price sensitivity matrix, M . The expression requires information about network topology and parameters, as well as the rules used to operate the market. While computing the matrix is conceptually easy for those with all the market and system information, such as an independent system operator, the method is probably impractical for market participants due to the inaccessibility of much of the information. In this paper, a method for estimating the M matrix by using publically available data are suggested, indicating that any market participant who does the computation will know when conditions permit them to lower or raise prices through decreased/increased bids and/or offers.

https://e3rg.pserc.cornell.edu/files/Copy%20of%20Estimation%20of%20A%20Sensitivity-Based%20Metric%20for%20Detecting%20Market%20Power.pdf

Robert J. Thomas

Papers

An Integrated Design Approach for Sustainable Community Development

Testing the Effects of Price Responsive Demand on Pay-as-Offered and Soft-Cap Electricity Auctions.

Geographical averaging and ancillary services for stochastic power generation

Power grid vulnerability measures to cascading overload failures

Estimation of a Sensitivity-Based Metric for Detecting Market Power