North American Electric Reliability Council Research Articles

Regulation services boost control performance [power systems

As the electric power industry becomes more competitive, new and innovative techniques will be required to produce electric power reliably and economically. The need for control areas to properly regulate generation while meeting the load requirement continues to be one of the more important control area functions in modern power system operations. The cost of control and the abilities of areas to perform rapid control response varies significantly throughout the North American Electric Reliability Council (NERC). Beginning in January 1995, Houston Lighting and Power Company began providing regulation service to the Lower Colorado River Authority control area to assist it in meeting the control performance standards established by NERC. This bold concept has enabled one control area to assist another with its obligations while maintaining a true independent operation within each area. The authors describe the technical approach to the concept.

Practices and new concepts in power system control

This paper reviews the existing power system control practices (both inside and outside of North America) and considers their ability to cope with the new regulatory and technological changes facing the electric supply industry in the present and near future. New or revised control practices are also methodically analyzed to see how they could meet the evolving power system control needs. Given both the trend of technological advances over the last decade and the expectation that those trends will continue, the near future holds opportunities for tremendous improvements in power system control. Key issues were identified and used to review possible directions for the concepts, philosophy, and guiding principles for power system control. Input comes from the electric supply industry through questionnaires, various relevant industry meetings, published materials, review of other on-going research, and working meetings with the North American Electric Reliability Council Performance Subcommittee. This research was sponsored by the Electric Power Research Institute (EPRI).

APPLICATION OF INERTIAL LOAD TO A LOSS OF GENERATOR POSTMORTEM

ABSTRACT The inertial load flow technique [2] is applied to a dynamic equivalent [1] derived from a NERC (North American Electric Reliability Council) data base to compute maximum tie line power flows for a 1980 MW loss of generation at the Nanticoke station in the Ontario Hydro system. The results were compared with a transient stability simulation and recorded tie line power and frequency measurements. The inertial load flow results were more accurate in capturing the filtered measurements of power flows during the first three to five seconds after a loss of generation contingency than the transient stability simulation. The transient stability simulation was shown to contain both synchronizing oscillations between generators as well as the quasi steady-state behavior captured by the filtered power measurements and inertial load flow. The inertial load flow is an excellent tool for estimating proximity to voltage collapse since the field current limiters on exciters utilize filtered measurements of the inertial response that occurs 3-5 seconds after a loss of generation contingency. The loss of voltage control and reactive generation supply due to action of field current limiters is a principle cause of loss of voltage stability in power systems. The inertial response is shown to capture a filtered estimate of the peak of the deceleration wave that propagates from the point of disturbance and would indicate whether the filtered estimate of these peak real power flows would incur sufficient filtered generator field current levels to cause field current limiters to act. Generator field current levels rise in an attempt to counteract voltage decline and increase in reactive losses caused by the peak power flows that are observed in the inertial response. The action of the field current limiter reduces field current and reactive supply to prevent thermal damage to the generator. The action of field current limiters initiates the voltage decline that can result in voltage collapse.

A simple method for improving control area performance: area control error (ACE) diversity interchange ADI

Power system control areas within three major (and essentially separate) areas of North America are interconnected electrically, thus enjoying vastly improved reliability and economy of operation compared to operating in isolation. Each must continually balance load, interchange and generation to minimize adverse influence on neighboring control areas and interconnection frequency. This requires investment in control systems and the sacrifice of some fuel conversion efficiencies to achieve the objective of complying with minimum control performance standards set by the North American Electric Reliability Council (NERC). Control also increases wear and tear on machinery in the pursuit of these goals. Area control area (ACE) diversity interchange (ADI) offers a means of reducing this control burden without undue investment or sacrifice by any participant in a group. This paper describes the philosophy of ADI and the ENEREX partnership's favorable experiences with its actual implementation in Iowa.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Forecasting supply and demand with reliable facts and figures

One activity of the North American Electric Reliability Council (NERC) is the annual compilation of electric utilities' forecast relating to electricity supply and demand. The author describe how this data is available to the industry in a database and software package known as ES&D, which provides data in a concise and useful format to satisfy the needs of a wide variety of industry audiences. From the mid-1970s to 1993, ES&D was published as a printed report. Since 1994, it has been published only in electronic format, with each publication including the current forecast data set and the four most recent data sets.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Tie-line bias prioritized energy control

This paper reviews relevant operating objectives established by the North American Electric Reliability Council, NERC. It shows that the present definition for area control error (ACE) is somewhat subjective. It further argues that unconditional reaction to small ACE does not optimize interconnection objectives. This paper evolves tie-line bias control objectives into a tie-line bias prioritized energy control philosophy it argues that utilization of this philosophy would enhance maintenance of frequency, reduce inadvertent energy accumulations and time error excursions, simultaneously increasing benefits of interconnected operation and their equitable distribution to member areas. The final details and tuning for a comprehensive AGC wedge control steering algorithm are being developed at American Electric Power (AEP).< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

CPC revisited [power system control

For over 20 years, the North American Electric Reliability Council Operating Committee's (NERC-OC) Performance Subcommittee has been using the Control Performance Criteria (CPC) to evaluate the control performance of NERC's control areas. A new, more comprehensive CPC criteria is being put through its trial period by the Performance Subcommittee. The author reviews how the current CPC was developed, implemented, and used to date. >

Sampling ACE data for NERC CPC surveys

The North American Electric Reliability Council (NERC) requests that utilities collect area control error (ACE) information and report each month their performance in meeting the control performance criteria (CPC) set by NERC. NERC has also requested that utilities store data on diskettes for analysis and development of new criteria to reflect more accurately the performance of the control area. The integration of the equipment used to collect and store the required data and the software necessary for automation of the data gathering and analysis are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The nuclear option for US electrical generating capacity additions utilizing boiling water reactor technology

The technology status of the advanced boiling water reactor (ABWR) and the simplified boiling water reactors (SBWR) is presented along with an analysis of the economic potential of advanced nuclear power generation systems based on BWR technology to meet the projected domestic electrical generating capacity need through 2005. The forecasted capacity needs are determined for each domestic North American Electric Reliability Council (NERC) region. Extensive data sets detailing each NERC region's specific generation and load characteristics, and capital and fuel cost parameters are utilized in the economic analysis, by means of an expansion planning model, of the optimal generation additions required to meet this need. In addition to a reference case, several sensitivity studies are performed with regard to capital costs and fuel price escalation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Electric supply and demand in the United States: next 10 years

The structure and activities of the North American Electric Reliability Council (NERC) are described. Their forecasts for the ten years ahead are discussed. Key issues that could prevent meeting reliability goals are highlighted. >

A Survey of Current Operational Problems

This paper is one of a series prepared for use in the Working Group on Current Operational Problems (COPS) forums with the goal of focusing attention of the industry on problems faced by those who are involved in actual power system operation. The questionnaire was sent to System Operation Subcommittee members and to North American Electric Reliability Council (NERC) key operating members. One hundred thirty responses were received. The high priority topics identified as problems by the survey can be divided up into three categories of people, analysis and control, and computer system. Some of the items, for example, Dispatcher Training Simulator could be assigned to any of these new categories. We arranged them as follows: People Problems-Dispatcher Training Simulators Management Problems due to Shift Work Evaluation of Training Programs Simulators to Practice System Restoration Job Desirability Dispatcher Selection Relations with Dispatchers Analysis and Control Problems - Key Monitoring Indicators Load Shedding System Condition Assessment Contingency Voltage Levels Transmission Access and Compensation Generation Cycling Resource Scheduling Computer System Problems - Alarms (present techniques need improvement) Alarming (Artificial Intelligence systems are needed) Performance Considerations (Computer systems handling inadequately during emergencies)

Fossil Unit Performance—1965–1984

This paper presents an overview of the results of a study performed for EPRI covering the historical performance of fossil-fired units 200 MW and larger from 1965 through 1984. The study was based on analysis of the information collected over the years by the Equipment Availability Task Force of the Prime Movers Committee of the Edison Electric Institute (EEI), and more recently by the North American Electric Reliability Council (NERC), and covers approximately 7700 unit-years of operation at 668 individual units.

Joint development and consistent bulk transmission outage reporting and analysis procedures by two NERC regions

Two North American Electric Reliability Council (NERC) regions, the Mid-Continent Area Power Pool and the Mid-America Interconnected Network, have individually collected bulk transmission outage data for a number of years. Based on recent research work, the members of the two regions realized that related multiple outages significantly affect bulk transmission system reliability. However, no existing data collection methods provided sufficient data to report and analyze adequately relationships between multiple outages. The experiences of these NERC regions working together to derive a consistent bulk transmission performance analysis package are discussed. The resultant data collection philosophy and format and the expected analysis capability are reviewed. Potential benefits of standardizing data formats and definitions are presented. >

Joint Development of Consistent Bulk Transmission Outage Reporting and Analysis Procedures by Two NERC Regions

Two North American Electric Reliability Council (NERC) regions, the Mid-Continent Area Power Pool and the Mid-America Interconnected Network, have individually collected bulk transmission outage data for a number of years. Based on recent research work, the members of the two regions realized that related multiple outages significantly affect bulk transmission system reliability. However, no existing data collection methods provided sufficient data to report and analyze adequately relationships between multiple outages. The experiences of these NERC regions working together to derive a consistent bulk transmission performance analysis package are discussed. The resultant data collection philosophy and format and the expected analysis capability are reviewed. Potential benefits of standardizing data formats and definitions are presented. >

The NERC Fan in Retrospect and Lessons for the Future

Projections of the future demand for electricitypublished annually since 1974 by the North American Electric Reliability Council (NERC) have proved in retrospect to have been too high and the projected growth rate has been revised downward each year. Should forecasters have been able to do a better job of predicting the slowdown in electricity growth which has occurred since the early 1970s? The authors have attempted to provide partial answers to this question by comparing the published NERC projections with benchmark forecasts provided by simple models representing well-established techniques. The authors also discuss how modelers and planners can cope with uncertainty by using the techniques of decision analysis.

Assessing the dollar price tag for meeting the NERC 10-minute reserve rule

The operating guideline formulated by the North American Electric Reliability Council (NERC) requires electric utilities to maintain enough online generation reserves to cover their worst generation and load contingency. To comply with this rule, most utilities carry enough 10-min reserves to cover the loss of their largest generating resource and/or 5-10% uncertainty in their load forecast. The authors present the results of a parametric study, performed for the Middle South Control Area, to quantify the cost of carrying short-term generation reserves.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

You only miss it when it's not there [establishment of North American Electric Reliability Council (NERC)

In the wake of the 9 Nov. 1965 blackout in the Northeast US, the North American Electric Reliability Council (NERC) was formed in 1968 by the electric utilities to promote the reliability of their generation and transmission systems. Today, NERC is comprised of nine Regional Reliability Councils, all pledged to planning and operating reliable electric systems. The Electric Reliability Council's Organizations and NERC's functions are briefly described.

Power System Restoration???The Second Task Force Report

In its second report, the Power System Restoration Task Force [1] reviews the 1979-83 North American Electric Reliability Council (NERC Reports on Major Bulk Power System Disturbances [2], identifying restoration problems which have been encountered during that five-year period. The report also briefly discusses the applicability of several existing programs to the system restoration process and the need for establishing guidelines based on approximate analysis for restoration enhancement. The opinions and conclusions expressed in this paper are those of the authors; they are based on the referenced reports and have not been reviewed with NERC or the reporting utilities.

Power System Restoration - The Second Task Force Report

In its second report, the Power System Restoration Task Force (PSR-TF) (1) reviews the 1979-83 North American Electric Reliability Council (NERC) Reports on Major Bulk Power System Disturbances (2), identifying restoration problems which have been encountered during that 5-year period. Generally, these problems fall into three phases of restoration activities: planning for restart, reintegration and restoration of the bulk power supply; control actions during system degradation for saving and retaining critical sources of power; and restoration after a major disturbance when the power system has stabilized. The report also briefly discusses the applicability of several existing programs to the system restoration process. The opinions and conclusions expressed in this paper are those of the authors; they are based on the referenced reports and have not been reviewed with NERC or the reporting utilities.

The NERC Fan: A Retrospective Analysis of the NERC Summary Forecasts

Summary forecasts of the growth in demand for electricity, published annually since 1974 by the North American Electric Reliability Council, have proved to be excessively optimistic, although the projected growth rate has been revised downward each year. Should forecasters have been able to do a better job of predicting the slowdown in demand growth since the early 1970s? Should they have responded more quickly as actual demand growth fell short of projections? Our objective in this article is to provide some partial answers to these questions by comparing the published NERC Summary Forecasts (NSF) with benchmark forecasts provided by simple models representing well-established techniques. One alternative forecast is provided by the exponential smoothing/Box-Jenkins method (ES/BJ) and another by a simple dynamic demand equation that uses real price and real income as explanatory variables. We conclude that relative to ES/BJ, the NSF were not excessively optimistic. Relative to the simple demand equation, ...