Harold Kirkham

A Survey of Wireless Communications for the Electric Power System

A key mission of the U.S. Department of Energy (DOE) Office of Electricity Delivery and Energy Reliability (OE) is to enhance the security and reliability of the nation’s energy infrastructure. Improving the security of control systems, which enable the automated control of our energy production and distribution, is critical for protecting the energy infrastructure and the integral function that it serves in our lives. The DOE-OE Control Systems Security Program provides research and development to help the energy industry actively pursue advanced security solutions for control systems. The focus of this report is analyzing how, where, and what type of wireless communications are suitable for deployment in the electric power system and to inform implementers of their options in wireless technologies. The discussions in this report are applicable to enhancing both the communications infrastructure of the current electric power system and new smart system deployments. The work described in this report includes a survey of the following wireless technologies: • IEEE 802.16 d and e (WiMAX) • IEEE 802.11 (Wi-Fi) family of a, b, g, n, and s • Wireless sensor protocols that use parts of the IEEE 802.15.4 specification: WirelessHART, International Society of Automation (ISA) 100.11a, and Zigbee • The 2, 3, and 4 generation (G )cellular technologies of GPRS/EDGE/1xRTT, HSPA/EVDO, and Long-Term Evolution (LTE)/HSPA+UMTS.

Centralized and decentralized control for demand response

Demand response has been recognized as an essential element of the smart grid. Frequency response, regulation and contingency reserve functions performed traditionally by generators are now starting to involve demand side resources. Additional benefits from demand response include peak reduction and load shifting, which will defer new infrastructure investment and improve generator operation efficiency. Technical approaches designed to realize these functionalities can be categorized into centralized control and decentralized control, depending on where the response decision is made. This paper discusses these two control philosophies and compares their response performances in terms of delay time and predictability. A distribution system model with detailed household loads and controls is built to demonstrate the characteristics of the two approaches. The conclusion is that the promptness and reliability of decentralized control should be combined with the controllability and predictability of centralized control to achieve the best performance of the smart grid.

Cyber-security considerations for the smart grid

The electrical power grid is evolving into the “smart grid.” The goal of the smart grid is to improve efficiency and availability of power by adding more monitoring and control capabilities. These new technologies and mechanisms are certain to introduce vulnerabilities into the power grid. In this paper we provide an overview of the cyber security state of the electrical power grid. We highlight some of the vulnerabilities that already exist in the power grid including limited capacity systems, implicit trust and the lack of authentication. We also address challenges of complexity, scale, added capabilities and the move to multipurpose hardware and software as the power grid is upgraded. These changes create vulnerabilities that did not exist before and bring increased risks. We conclude the paper by showing that there are a number mitigation strategies that can help keep the risk at an acceptable level.

Use of synchrophasor measurements in protective relaying applications

The IEEE PSRC System Protection Subcommittee Working Group C14 has produced a report that describes practical applications of synchrophasors in protection applications. The report begins with the history of synchrophasors and then goes into issues to consider in their application. Some existing applications are described and then future applications that have been considered or are in development are described. The appendix contains applications that use synchrophasor data but are not considered protection applications. This is a summary of the complete report found on the PSRC website (http://www.pes-psrc.org click on Published Reports).

Secure Data Transfer Guidance for Industrial Control and SCADA Systems

This document was developed to provide guidance for the implementation of secure data transfer in a complex computational infrastructure representative of the electric power and oil and natural gas enterprises and the control systems they implement. For the past 20 years the cyber security community has focused on preventative measures intended to keep systems secure by providing a hard outer shell that is difficult to penetrate. Over time, the hard exterior, soft interior focus changed to focus on defense-in-depth adding multiple layers of protection, introducing intrusion detection systems, more effective incident response and cleanup, and many other security measures. Despite much larger expenditures and more layers of defense, successful attacks have only increased in number and severity. Consequently, it is time to re-focus the conventional approach to cyber security. While it is still important to implement measures to keep intruders out, a new protection paradigm is warranted that is aimed at discovering attempted or real compromises as early as possible. Put simply, organizations should take as fact that they have been, are now, or will be compromised. These compromises may be intended to steal information for financial gain as in the theft of intellectual property or credentials that lead to the theft of financial resources, or to lie silent until instructed to cause physical or electronic damage and/or denial of services. This change in outlook has been recently confirmed by the National Security Agency [19]. The discovery of attempted and actual compromises requires an increased focus on monitoring events by manual and/or automated log monitoring, detecting unauthorized changes to a systems hardware and/or software, detecting intrusions, and/or discovering the exfiltration of sensitive information and/or attempts to send inappropriate commands to ICS/SCADA (Industrial Control System/Supervisory Control And Data Acquisition) systems.

Large-Scale PV Integration Study

This research effort evaluates the impact of large-scale photovoltaic (PV) and distributed generation (DG) output on NV Energy’s electric grid system in southern Nevada. It analyzes the ability of NV Energy’s generation to accommodate increasing amounts of utility-scale PV and DG, and the resulting cost of integrating variable renewable resources. The study was jointly funded by the United States Department of Energy and NV Energy, and conducted by a project team comprised of industry experts and research scientists from Navigant Consulting Inc., Sandia National Laboratories, Pacific Northwest National Laboratory and NV Energy.

Protecting the smart grid: A risk based approach

This paper describes a risk-based approach to security that has been used for years in protecting physical assets, and shows how it could be modified to help secure the digital aspects of the smart grid and control systems in general. One way the smart grid has been said to be vulnerable is that mass load fluctuations could be created by quickly turning off and on large quantities of smart meters. We investigate the plausibility.

Synchronous phasor-like measurements

This paper proposes a redefinition of the power system quantities often said to be described by a synchro-phasor and measured by a phasor measurement unit. Problems with what are often called “synchronous phasor measurements” include the facts that they are not truly synchronous, and the quantity being measured is not truly a phasor. This paper proposes a new method of making measurements that overcomes these problems. It tests the proposed definitions and measurement methods with “synthetic” signals, and shows that the method provides understandable and consistent results.

An Introduction to Goodness of Fit for PMU Parameter Estimation

It is posited that the process of measuring the various parameters that characterize a signal is equivalent to a fitting problem in mathematics. The equation being fit is a model based on the “physics” of the signal. The Fourier transform or rms calculations in a phasor measurement unit (PMU) furnish the values of the coefficients. Regardless of exactly how the measurement is made, a metric we define and call the goodness of fit allows the measuring system to comment on the match between the signal it is observing and the model. The metric is based on the residuals, the differences between the signal itself and the value calculated from the result of measurement. Results from real-word PMUs and real-world signals illustrate that the equation of the PMU is well solved during steady conditions. We examine the effect of a fault in the transmission system on the goodness-of-fit metric for a PMU. We also apply the metric to results from a microPMU in the distribution system.

Dealing with non-stationary signals: Definitions, considerations and practical implications

The paper addresses the question of how to deal with non-stationary power signals. The first part of the solution is at a fundamental level: the recognition that the thing being measured is known by some kind of label in a model. The label is attached to a some parameter in an equation, and is often identifiable by its position in the equation. The paper presents measurement as the act of solving the equation to find the value of the parameter. In other words, the equation is what metrologists term the measurand, and the measurement equipment must be designed around it. To measure a time-varying signal, in a world of digital measurements, one of the first questions that must be addressed is the relationship between the sampling window of the measurement system and the rate at which the signal is varying. A goodness of fit metric is identified. Several changing-frequency cases are examined.