North American Electric Reliability Council Research Articles

Adjustable Event-Triggered Load Frequency Control of Power Systems Using Control-Performance-Standard-Based Fuzzy Logic

This article proposesa control performance standard (CPS)-based fuzzy event-triggered scheme for load frequency control (LFC) of power systems with a limited communication bandwidth. First, a CPS-based fuzzy LFC system is established to reduce the wear and tear of the generating unit equipment. Then, based on the Lyapunov stability theory, a stability criterion of the LFC system is proposed to ensure the stable operation of the LFC system, which considers the threshold parameter of the event-triggered condition and the fuzzy gain in the fuzzy LFC system. Next, based on the stability criterion and the Gaussian-type curve-fitting method, a functional expression between the fuzzy gain and the threshold parameter is obtained. According to the expression, the threshold parameter is updated in real time with the change of fuzzy gain, so as to further save usage of the communication network bandwidth. Case studies based on a one-area power system and an IEEE 39-bus benchmark test system are undertaken. Simulation results show that the proposed scheme achieves three objectives: 1) to comply with CPS1 and CPS2 in the North American Electric Reliability Council; 2) to reduce wear and tear of the generating unit equipment; and 3) tosave more communication network resources.

Marginal Cost-Based Reactive Power Reinforcement Using Dynamic and Static Compensators

The main philosophy of this article is to develop customer-persuaded electric power tariff scheme, based on the composition of additionally required services. Ancillary services may be categorized into desirable and essential electric power market services and so independent system operator (ISO) looks into the rights of all the utilities involved in the electric power market for getting the most acceptable rate of electrical energy in favor of all. Reactive power compensation, one of the 12 ancillary services underlined by North American Electric Reliability Council (NREC) along with Electric Power Research Institute (EPRI), is necessarily important to attend the voltage profile at load terminals. STATCOM, a dynamic compensator, has more advanced technologies over a fixed capacitor (FC), which is a static compensator; however, its involvement results in more financial burden to utilities. This article reinforces an adequate reactive power compensation scheme, for attending static and dynamic load disturbances, using ISE criterion-based proposed current-controlled STATCOM with FC in a grid-tied system. The composition of reactive power supplied by static and dynamic compensation is optimized using marginal cost, based on base and peak reactive power demand concept, keeping in mind the system frequency regulation. The results in terms of compensation scheme are compared for step changes in three load conditions and with and without static reactive power compensators.

Load Frequency Control in a Multi-Area Deregulated Power System with BBBC-based Discrete Fractional Order Control Scheme

Load frequency control (LFC) for multi-area restructured power system using discrete controlscheme has been suggested in this paper. The proposed LFC scheme utilizes synchronously measured dataof frequency and tie-line power to calculate area control error (ACE). A discrete non-integer proportionalintegral derivative controller (D-FOPID) has been used to derive frequency error to zero. Two-area thermaland four-area hydro thermal deregulated power system has been used to investigate various LFC issues. Theoptimal factors of D-FOPID have been obtained using big bang big crunch (BBBC) algorithm. The systemresults under MATLAB/Simulink validate that D-FOPID effectively work under different types of contractscenarios. D-FOPID performance has also been compared to discrete proportional integral derivativecontroller (D-PID). Further the compliance with control standards of North American electric reliabilitycouncil (NERC) has also been ensured for both the controller.

Reliability prediction and its validation for nuclear power units in service

In this paper a novel method for reliability prediction and validation of nuclear power units in service is proposed. The equivalent availability factor is used to measure the reliability, and the equivalent availability factor deducting planed outage hours from period hours and maintenance factor are used for the measurement of inherent reliability. By statistical analysis of historical reliability data, the statistical maintenance factor and the undetermined parameter in its numerical model can be determined. The numerical model based on the maintenance factor predicts the equivalent availability factor deducting planed outage hours from period hours, and the planed outage factor can be obtained by using the planned maintenance days. Using these factors, the equivalent availability factor of nuclear power units in the following 3 years can be obtained. Besides, the equivalent availability factor can be predicted by using the historical statistics of planed outage factor and the predicted equivalent availability factor deducting planed outage hours from period hours. The accuracy of the reliability prediction can be evaluated according to the comparison between the predicted and statistical equivalent availability factors. Furthermore, the reliability prediction method is validated using the nuclear power units in North American Electric Reliability Council (NERC) and China. It is found that the relative errors of the predicted equivalent availability factors for nuclear power units of NERC and China are in the range of–2.16% to 5.23% and–2.15% to 3.71%, respectively. The method proposed can effectively predict the reliability index in the following 3 years, thus providing effective reliability management and maintenance optimization methods for nuclear power units.

Generating adequacy analysis of Mexico’s national interconnected power system

Purpose Long-term reliability analysis of generation capacity based on the forecasted load demand helps to identify the optimal generation expansion plan of the system. This paper analyzes the generation adequacy of Mexico’s National Interconnected Power System (MNIPS) using loss of load expectation (LOLE) and loss of energy expectation (LOEE) indices. Design/methodology/approach These indices are calculated through an analytical (recursive) method and are then compared with values recommended by the North American Electric Reliability Council (NERC). Weekly indices are computed to analyze the load curtailment options that may occur in some periods. Findings Forecasted values, including load and generation capacity considering maintenance schedules, additions of new generating units and permanently shut down units in accordance with the long-term expanding-system plan have been considered. The load forecast uncertainty is also included. Originality/value This is original work.

A novel NERC compliant automatic generation control in multi-area power systems in the presence of renewable-energy resources

In this paper, a novel automatic generation control for a multi-area power system is developed. The proposed controller is based on the Immune-Reinforcement-Learning Algorithm and is capable of real-time adjustment to comply with North American Electric Reliability Council (NERC) control performance standards as well as decreasing the generators’ oscillations. High-renewable penetration, such as wind power, reduces the total inertia of the system which makes the system unable to recover from perturbation causing deterioration in the control performance standards. Because of the intermittency of the renewables, constant gain controllers do not perform well and tend to violate the NERC standards. The proposed algorithm acts in real time and adapts with changes in the renewable power as well as changes in the load to always comply with the standards while smoothly running the generators to reduce wear and tear. The proposed controller is implemented on a four-area power system and compared to different fixed value cases.

A Billion Dollar Investment: The Profitability of Investments in Emergency Energy Sources to Supplement Energy Infrastructure of Regions Vulnerable to Prolonged Outages

The American economy suffers a $150 billion annual loss inherent to power disruptions. American economic and societal structures are increasingly energy dependent, and often solely on grid supplied energy sources. American's great dependence on the expansive national power grid conveys the need to encourage investments in emergency back-up alternate energy sources. Hurricane Katrina proved the most expensive natural disaster in the history of the United States. The storm exposed the country to the vulnerabilities faced with prolonged power outages. When New Orleans’ hospitals experienced total depletions of power physicians were left hopeless. Patients, in the world’s leading energy producer, lost their lives because they needed power dependent technology. The costs of natural disasters have significantly increased over the past twenty years. Though this is often attributed to climate change, it is rarely considered with the recent expansion of the nation’s digital economy, which is disproportionately impacted by interruptions in energy supply. This article focuses on the immense economic benefit of grid independent back-up energy sources, especially within the regions that are most vulnerable to prolonged energy outages. It is vital the North American Electric Reliability Council along with the entire energy regulatory community encourage expansion of back-up, grid independent energy sources for efficient, fiscally responsible disaster response. No previous articles have considered the costs of developing and interconnecting Distributed Generation into the current energy supply infrastructure congruent to costs avoided through greater resiliency. This article is the first to analyze the economic and societal benefits of investing in reliable back-up energy sources. Investments in Distributed Generation would curtail billions in losses incurred by the U.S. economy inherent to disruptions in power, and save the lives of many Americans.

Optimized load-frequency simulation in restructured power system with Redox Flow Batteries and Interline Power Flow Controller

This paper proposes the Load Frequency Control (LFC) of an interconnected two-area multiple-unit thermal reheat power system in a restructured environment. In the restructured scenario, various kinds of apparatus with large capacity and fast power consumption may cause a series problem of frequency oscillations. The oscillation of system frequency may sustain and grow to cause a series frequency stability problem if no adequate damping is available. Moreover, the larger amount of the steam stored in steam chest and reheater of thermal power plant delays the control valve motion to increase the mechanical power output after the load perturbation. So in order to stabilize the system, impacts of Interline Power Flow Controller (IPFC) in series with tie-line and Redox Flow Batteries (RFB) at the terminal of area 1 have been investigated. The Bacterial Foraging Optimization (BFO) algorithm is used to optimize the integral gains of the Load-frequency Controller under different transactions in the competitive electricity market. Compliance with North American Electric Reliability Council (NERC) standards for Load Frequency Control has also been established in this work. Simulation studies reveal that the RFB coordinated with IPFC units for LFC loop has greater potential for improving the system’s dynamic performance.

Control performance standards based load-frequency controller considering redox flow batteries coordinate with interline power flow controller

This paper proposes a sophisticate application of redox flow batteries (RFB) coordinate with Interline Power Flow Controller (IPFC) for the improvement of Load Frequency Control (LFC) of a multiple units two- area power system. The Interline Power Flow Controller is to stabilize the frequency oscillations of the inter-area mode in the interconnected power system by the dynamic control of tie-line power flow. The redox flow batteries, which are not aged to the frequent charging and discharging, have a quick response and outstanding function during overload conditions. In addition to leveling load, the battery is advantageous for secondary control in the power system and maintenance of power quality of distributes power resources. The Bacterial Foraging Optimization (BFO) algorithm is use to optimize the parameters of the cost functions for designing the integral controller. Compliance with North American Electric Reliability Council (NERC) standards for Load Frequency Control has also been establishes in this work. Simulation studies reveal that the RFB coordinate with IPFC units has greater potential for improving the system dynamic performance.

Special Issue on Restructuring and Sustainable Development for China’s Electric Power Industry

Special Issue on Restructuring and Sustainable Development for China’s Electric Power Industry

Genetic algorithm based PID controller design for a multi-area AGC scheme in a restructured power system

In this paper, a multi-area Automatic Generation Control (AGC) scheme suitable in a restructured interconnected power system has been proposed. Developed scheme utilizes a proportional, integral and derivative (PID) controller to control the output of the generators. The parameter of PID controller has been tuned according to Genetic Algorithm (GA) based performance indices. Developed model also include the Superconducting Magnetic Energy Storage (SMES) units to inject or absorb the active power of an interconnected power system. The functioning of Genetic Algorithm based PID controller has been tested on a 39-bus New England system and 75-bus Indian power system network. The results of GAPID controller have been compared with those obtained by using the Least Square Minimization method. Compliance with North American Electric Reliability Council (NERC) standards for AGC has also been established in this work.

Root cause failure analysis of a division wall superheater tube of a coal-fired power station

Coal-fired boiler tubes are generally exposed to high internal pressure and high temperature of steam and flue gas. The common cause of any metallurgical failure of a superheater tube is due to the tube metal temperature higher than that as originally specified [1]. Tube metal temperature may increase gradually over many years due to the growing oxide scales inside tube or elevate rapidly caused by loss of internal steam or water-coolant flow. Internal pressurized tubes are critical components in water-tube boiler and steam superheater elements. Tubes in such application are vulnerable to high temperature upset condition, undergoing severe creep deformation or even final rupture. Therefore, boiler tubes in power plants have finite life because of prolonged exposure to high temperature, stress, aggressive environment, corrosive degradation, etc. However, uses of suitable boiler tube material in thermal power plants are required to ensure that the materials are safely used under higher temperatures and pressures for a long period of operation [2]. Many works concerning the failure problems in water-tube boiler have been reported. The North American Electric Reliability Council (NERC) reported that the coal-fired boilers are among the highest economic risk components in any other power plant. By far, the greatest number of forced outages in all types of boiler is caused by failures [3]. Elimination of boiler tube failure could save the electric power industry about $5 billion a year [4]. Metallurgists from French, Inc. [1] published data of the top 10 causes of failures where creep (long-term overheating) is 23.4%, followed by fatigue (13.9%) (thermal 8.6%, corrosion 5.3%), ash corrosion (12.0%), hydrogen damage (10.6%), weld failures (9.0%), high temperature (short-term overheating) (8.8%), erosion (6.5%), oxygen pitting (5.6%), caustic attack (3.5%) and stress corrosion cracking (2.6%). In general, 30% of all tube failures in boilers and reformers are caused by creep [5–7].

Stochastic Optimal CPS Relaxed Control Methodology for Interconnected Power Systems Using Q-Learning Method

This paper presents the application and design of a novel stochastic optimal control methodology based on the Q-learning method for solving the automatic generation control (AGC) under the new control performance standards (CPS) for the North American Electric Reliability Council (NERC). The aims of CPS are to relax the control constraint requirements of AGC plant regulation and enhance the frequency dispatch support effect from interconnected control areas. The NERC’s CPS-based AGC problem is a dynamic stochastic decision problem that can be modeled as a reinforcement learning (RL) problem based on the Markov decision process theory. In this paper, the Q-learning method is adopted as the RL core algorithm with CPS values regarded as the rewards from the interconnected power systems; the CPS control and relaxed control objectives are formulated as immediate reward functions by means of a linear weighted aggregative approach. By regulating a closed-loop CPS control rule to maximize the long-term discounted...

Large blackouts in North America: Historical trends and policy implications

Using data from the North American Electric Reliability Council (NERC) for 1984–2006, we find several trends. We find that the frequency of large blackouts in the United States has not decreased over time, that there is a statistically significant increase in blackout frequency during peak hours of the day and during late summer and mid-winter months (although non-storm-related risk is nearly constant through the year) and that there is strong statistical support for the previously observed power-law statistical relationship between blackout size and frequency. We do not find that blackout sizes and blackout durations are significantly correlated. These trends hold even after controlling for increasing demand and population and after eliminating small events, for which the data may be skewed by spotty reporting. Trends in blackout occurrences, such as those observed in the North American data, have important implications for those who make investment and policy decisions in the electricity industry. We provide a number of examples that illustrate how these trends can inform benefit-cost analysis calculations. Also, following procedures used in natural disaster planning we use the observed statistical trends to calculate the size of the 100-year blackout, which for North America is 186,000 MW.

Global Cooling: Electricity Peak-shaving Techniques to Offset Climate Change

ABSTRACT Electricity is the “power to succeed.” However, the United States faces a hidden electricity crisis, i.e., the “power to fail.” As the economy grows at 2–3 percent per year, the total demand for electricity has grown in tandem at 2.1 percent per year over the 1994–2004 period. Inversely, however, electricity capacity margins, the percent of “spinning” supply above demand, have declined consistently over the last decade from 25–30 percent in 1992 to about 15 percent today. In fact, the Eastern Independent Power Grid, with nearly 75 percent of total U.S. electricity demand, has only a 13.9 percent capacity margin. Additionally, the North American Electric Reliability Council (NERC) forecast in 2006 that overall electricity demand will rise 19 percent by 2015, but overall electricity capacity will rise only 6 percent. This compound total demand growth coupled with declines in utility plant capacity margins only masks the serious underlying problem: peak electricity demand, typically for summertime air conditioning, is growing at 2.6 percent per year, consistently as fast as total electricity demand. While the nation considers the need for energy independence critical due to the fact that half the nation's oil consumption is imported, the resulting economic consequences of a peak electricity shortfall would be as bad or worse, given the nation's reliance on electricity to cool, light, and power motors and computers. That is the nexus of this article: the available energy technologies and programmatic procedures to reduce electricity peaks or peak-shaving in the U.S.

Risk‐Management and Risk‐Analysis‐Based Decision Tools for Attacks on Electric Power

Incident data about disruptions to the electric power grid provide useful information that can be used as inputs into risk management policies in the energy sector for disruptions from a variety of origins, including terrorist attacks. This article uses data from the Disturbance Analysis Working Group (DAWG) database, which is maintained by the North American Electric Reliability Council (NERC), to look at incidents over time in the United States and Canada for the period 1990-2004. Negative binomial regression, logistic regression, and weighted least squares regression are used to gain a better understanding of how these disturbances varied over time and by season during this period, and to analyze how characteristics such as number of customers lost and outage duration are related to different characteristics of the outages. The results of the models can be used as inputs to construct various scenarios to estimate potential outcomes of electric power outages, encompassing the risks, consequences, and costs of such outages.

Modeling the impacts of climate policy on the deployment of carbon dioxide capture and geologic storage across electric power regions in the United States

This paper summarizes the results of a first-of-its-kind holistic, integrated economic analysis of the potential role of carbon dioxide (CO 2) capture and storage (CCS) technologies across the regional segments of the United States (U.S.) electric power sector, over the time frame 2005–2045, in response to two hypothetical emissions control policies analyzed against two potential energy supply futures that include updated and substantially higher projected prices for natural gas. This paper's detailed analysis is made possible by combining two specialized models developed at Battelle: the Battelle CO 2 -GIS to determine the regional capacity and cost of CO 2 transport and geologic storage; and the Battelle Carbon Management Electricity Model, an electric system optimal capacity expansion and dispatch model, to examine the investment and operation of electric power technologies with CCS against the background of other options. A key feature of this paper's analysis is an attempt to explicitly model the inherent heterogeneities that exist in both the nation's current and future electricity generation infrastructure and in its candidate deep geologic CO 2 storage formations. Overall, between 180 and 580 gigawatts (GW) of coal-fired integrated gasification combined cycle with CCS (IGCC + CCS) capacity is built by 2045 in these four scenarios, requiring between 12 and 41 gigatonnes of CO 2 (GtCO 2) storage in regional deep geologic reservoirs across the U.S. Nearly all of this CO 2 is from new IGCC + CCS systems, which start to deploy after 2025. Relatively little IGCC + CCS capacity is built before that time, primarily under unique niche opportunities. For the most part, CO 2 emissions prices will likely need to be sustained at over $20/tonne CO 2 before CCS begins to deploy on a large scale within the electric power sector. Within these broad national trends, a highly nuanced picture of CCS deployment across the U.S. emerges. Across the four scenarios studied here, power plant builders and operators within some North American Electric Reliability Council (NERC) regions do not employ any CCS while other regions build more than 100 GW of CCS-enabled generation capacity. One region sees as much as 50% of its geologic CO 2 storage reservoirs’ total theoretical capacity consumed by 2045, while most of the regions still have more than 90% of their potential storage capacity available to meet storage needs in the second half of the century and beyond. A detailed presentation of the results for power plant builds and operation in two key regions: ECAR in the Midwest and ERCOT in Texas, provides further insight into the diverse set of economic decisions that generate the national and aggregate regional results.

Overcoming restoration challenges associated with major power system disturbances - Restoration from cascading failures

A study of annual system disturbances reported by the North American Electric Reliability Council (NERC) over a ten-year period shows 117 power system disturbances that have had one or more restoration problem(s) belonging to a number of functional groups. While this paper does not include all the restoration problems encountered, some of the more common and significant problems are briefly described. These failures clearly indicate a need for renewed emphasis on developing restoration methodologies and implementation plans

A Decentralized Automatic Generation Control Scheme for Competitive Electricity Markets

This paper presents the design of a decentralized automatic generation control (AGC) scheme for interconnected multiarea power system. The proposed controller incorporates various types of transactions taking place in a competitive electricity market. The controller has been designed by appropriately assigning the eigenstructure of each isolated subsystem via state feedback, satisfying the sufficient conditions for stability. The functioning of the proposed decentralized controller has been demonstrated on a 39-bus New England system and a 75-bus Indian power system, and the results have been compared with those obtained by using a centralized control scheme. Compliance with the North American Electric Reliability Council standards for AGC has also been established.

Reenergizing the grid: greater regulatory, legislative certainty needed

The North American Electric Reliability Council's (NERC) new reliability standards are an important milestone for the council and the electric power industry. They clarify existing NERC reliability standards, and they create the foundation for adopting enforceable standards. The grid ensure that the nation's retail electricity customers enjoy reliable and affordable electricity service, and it enables the country's evolving wholesale electricity markets. To support both functions in the future, the grid will require more investment. The nation's shareholder-owned electric utilities recognize this need and are building transmission facilities. Even with this new spending, the continually growing demand for electricity, coupled with the expanding number of wholesale market transactions, means that more investment will be necessary. To encourage it, a number of regulatory and legislative policies should be adopted at both the federal and the state level to improve investor certainty and cost recovery.