Virginia Power Research Articles

Design, Testing, and Implementation of a Linear State Estimator in a Real Power System

As more phasor measurement units (PMUs) are installed, portions of the power grid become observable with just phasor measurements, making feasible the estimation of the state of these observable portions at much faster rates than the traditional state estimator. Although such a linear state estimator (LSE) was proposed over a decade ago, the first field implementation was completed at Dominion Virginia Power in 2013. Although this LSE is a stand-alone function not integrated to their energy management system (EMS), it demonstrated the feasibility of the LSE. In this paper, we present the design, development, and implementation of an LSE that is fully integrated with the existing EMS and can estimate the state of the extra high voltage portion of a power system at 30 times per second. Integration of the LSE to the existing EMS environment and some of the issues in the design and testing are presented in this paper. The work paved way for LSE to supply cleansed PMU data to other synchrophasor applications that are sensitive to data quality.

Binary particle swarm optimisation‐based optimal substation coverage algorithm for phasor measurement unit installations in practical systems

Phasor measurement units (PMUs) play an important role in the wide-area monitoring and protection of modern power systems. Historically, their deployment was limited by the prohibitive cost of the device itself. Therefore, the objective of the conventional optimal PMU placement problem was to find minimum number of devices, which when carefully placed throughout the network, maximised observability subject to different constraints. Due to improvements in relay technology, digital relays can now serve as both relays and PMUs. Under such circumstances, the substation installations consume the largest portion of the deployment cost, and not the devices themselves. Thus, for minimising cost of synchrophasor deployment, number of substation installations must be minimised. This study uses binary particle swarm optimisation to minimise number of substations in which installations must be performed for making all voltage levels observable, while being subject to various practical constraints. Standard IEEE systems have been used to explain the technique. Finally, a large-scale network of Dominion Virginia Power is used as the test bed for implementation.

Methodology for Performing Synchrophasor Data Conditioning and Validation

A phasor measurement unit (PMU) only state estimator is intrinsically superior to its SCADA analogue with respect to speed, performance, and reliability. However, ensuring the quality of the data stream which enters the linear estimator is crucial before establishing it as the front end of an EMS or other network applications. One approach is to pre-process the phasor data before it arrives at the linear estimator. This paper presents an algorithm for synchrophasor data conditioning and repair that fits neatly as a prefix into the existing linear state estimation formulation. The methodology has been tested using field data obtained from PMUs installed in Dominion Virginia Power's (DVP's) EHV network. The results indicate that the proposed technique provides a computationally simple, elegant solution to the synchrophasor data quality problem.

Wide Area System Islanding Contingency Detecting and Warning Scheme

In this paper, a strategy for online detecting and warning of wide area power system islanding disturbances using real time PMU data is introduced and tested. The proposed method is composed of an intelligent decision tree algorithm for islanding detection and identification with the aid of an islanding database made of islanding simulations, real world islanding records, and system geographical/topology information. The practical utilization adopting this method in the Dominion Virginia Power system and the functional module design are also introduced.

Experimental investigation of char generated from co-pyrolysis of coal and Appalachian hardwoods

In recent years, there has been increased interest in the co-combustion and co-gasification of coal and biomass materials in many industrial applications. The primary driving force behind this interest lays in the fact that co-combustion and co-gasification of coal biomass material are viewed to be a more carbon-neutral approach to processes typically used for power generation, as well as generation of syngas and other coal-derived chemicals. With the addition of renewable biomass materials to the coal used in these processes, the net amount of carbon dioxide released to the atmosphere is effectively reduced due to the assumption that replenishment of the biomass via replanting will lead to carbon dioxide removal via photosynthesis.The current study investigates co-pyrolysis of coal and biomass feedstocks, a precursor to the co-combustion or co-gasification reactions when both materials are fed together into the combustor or gasifier. Experiments have been conducted in which different mixtures of typical West Virginia power plant blend coals and Appalachian hardwoods have undergone pyrolysis using a tube furnace. Measurements were made with samples that contained 100% coal, 100% biomass as well as a 50% coal/50% biomass mixture. In addition, two different particle size ranges were used in order to examine the effect of particle size on the resulting pyrolysis products. In each experiment, the coal and biomass mixtures were heated to 500°C in a nitrogen atmosphere. Samples of the resulting solid char were collected and analyzed via ultimate and proximate analysis, and Fourier transform infra-red spectrometry (FT-IR).Numerous authors have debated whether or not the addition of biomass material to coal generates a synergistic, non-linear effect upon the resulting pyrolysis products. The data obtained during the current study suggests that varying the biomass content in the initial feed stock shows linearity with respect to the proximate and ultimate (elemental) analysis results of the produced chars; however, non-linearities can be seen in the tar and char yields, and in the functional group structure of the chars, as revealed by FT-IR analysis of the solid char samples.

North Anna Nuclear Power Plant Strong-Motion Records of the Mineral, Virginia, Earthquake of 23 August 2011

The M w 5.8 Mineral, Virginia, earthquake was recorded at an epicentral distance of about 18 km at the North Anna Nuclear Power Plant (NPP) by the magnetic tape digital accelerographs installed inside the plant’s containment at the foundation and deck levels. The North Anna NPP is operated by the Virginia Electric and Power Company (VEPCO) commonly called Dominion Power Company and has two pressurized water reactor (PWR) units that began operation in 1978 and 1980. Following the earthquake, both units were safely shut down. The strong‐motion records were processed to get velocity, displacement, Fourier amplitude, and 5%‐damped response spectra. The basemat record demonstrated relatively high amplitudes of acceleration of ![Graphic][1] and velocity of 13.8 cm/s with a relatively short duration of strong motion of 2–3 s. The higher elevation containment‐deck record had peak acceleration of ![Graphic][2] and peak velocity of 26.1 cm/s. These accelerograms are the strongest ground motions ever recorded at a U.S. nuclear power plant. Basemat response spectra exceed the Design Basis Earthquake for the existing Units 1 and 2, whereas comprehensive plant inspections performed by Dominion and the U.S. Nuclear Regulatory Commission have concluded that the damage to the plant was minimal and not affecting any structures and equipment significant to plant operation. This can be explained in part by the short duration of the earthquake ground motion at the plant. The North Anna NPP did not have free‐field strong‐motion instrumentation at the time of the earthquake. Because the containment is founded on rock, there is a tendency to consider the basemat record as an approximation of the free‐field recording. However, comparisons of deck and basemat records demonstrate that the basemat recording is also affected by structural resonances in the frequency range of 3–4 Hz and higher. Therefore, future seismological interpretation of these recordings should take into account the effect of structure. [1]: /embed/inline-graphic-1.gif [2]: /embed/inline-graphic-2.gif

Modeling Geomagnetically Induced Currents in Dominion Virginia Power Using Extreme 100-Year Geoelectric Field Scenarios—Part 1

The main purpose of this series of papers is to provide methodology and best business practices to assess the risk posed by geomagnetic disturbances. This paper addresses the methodology used by Dominion Virginia Power to model geomagnetically induced currents. An extreme 100-year geoelectric-field scenario is utilized as a baseline. The impact of topology changes in a large 497-bus system is investigated. Subsequent papers-Parts II and III-will address transformer vulnerability and system voltage stability, respectively.

Overhead distribution conductor motion due to short-circuit forces

Overhead distribution conductors move as a result of short-circuit conditions. In some cases, this motion can lead to conductors swinging together closer to the source. The subsequent fault causes higher stresses on the substation transformer and causes a backup overcurrent protective device to operate, having a negative impact on reliability. This paper reports on an investigation involving conductor motion on Dominion Virginia Power's overhead distribution system. It builds upon prior work dealing with compact overhead transmission lines. The author extends the model to typical overhead distribution lines and provides guidance to the distribution engineer as to when conductor swinging might become a problem. The characteristics of the most vulnerable spans led to the development of time-current curves depicting regions where spans are likely to have problems from short-circuit forces. The resulting critical clearing time curves have been adopted by the author's company to minimize problems from swinging conductors.

Utilities and Industrial Customers: Partners in Energy Management

In today's competitive environment, many utilities are not onlypursuing new industrial customers, but actively working to help ex-isting industrial customers become more competitive and profitable.There is fierce competition among corporations, but there is alsocompetition between plants within the same company. As severalplants within one company become consolidated, each strives indi-vidually to survive. At Virginia Power we are working with ourindustrial customers to help them become as efficient as possiblewhile holding down energy costs.One of the most valuable tools that utilities have to offer forenergy management is the industrial energy survey (audit). Withinthe utility there is usually a department set up and trained with allthe proper tools and expertise to perform energy surveys. Let's face it,who should know energy better than the utility company. On theother hand, industrial plants know how to operate their own businessbetter than anyone else. If these two groups can work as partners,both can receive immediate, as well as long lasting benefits.A successful and lasting energy management program will havethe endorsement of the company's top management. A concise corpo-rate energy policy, employee involvement, a reliable progressreporting system, and employee training and responsibility are allvital elements for success . A winning program is an ongoing process,not a one shot effort.

Climate change and hydropower generation

Many electric utilities use small reservoirs in mountainous regions to generate hydropower to meet peak energy demands. Water input depends on the water budget of the catchment, whereas output depends on user demand, which is influenced by temperature. Hence reservoir performance depends on climatic factors and is sensitive to climate change. A model, based on the systems of Duke Power and Virginia Power in the south-eastern USA, was developed to simulate performance. The annual maximum draw-down of the reservoir, which represents the minimum dam size needed to maintain continuous energy generation, is considered here. The model was tested for four regions in the eastern USA using 1951–1995 observations. The amount of draw‒down depended on the linked daily sequences of precipitation and temperature, the former dictating the water available, the latter influencing both evaporation and energy demand. The time and level of the annual extreme emphasized that small changes in the timing of a dry spell had a major impact on the draw-down. Climatic changes were simulated by uniformly increasing temperatures by 2°C and decreasing precipitation by 10 per cent. The resultant draw‒down increased from current simulated values by about 10 per cent to 15 per cent with extremes up to 50 per cent. This was of the same order, but in the opposite direction, as the change created by a 10 per cent increase in the efficiency of energy generation. Without such an efficiency increase, many utilities will face the prospect of reduced or less reliable hydroelectric generation if climate changes in the manner examined here. © 1997 the Royal Meteorological Society.

Modeling Utility Load and Temperature Relationships for Use with Long-Lead Forecasts

Abstract Models relating system-wide average temperature to total system load were developed for the Virginia Power and Duke Power service areas in the southeastern United States. Daily data for the 1985–91 period were used. The influence of temperature on load was at a minimum around 18°C and increased more rapidly with increasing temperatures than with decreasing ones. The response was sensitive to the day of the week, and models using separate weekdays as well as one using pooled data were created. None adequately accounted for civic holidays or for extreme temperatures. Estimates of average loads over a 3-month period, however, were accurate to within ±3%. The models were used to transform the probability distribution of 3-month average temperatures for each system, derived from the historical record, into load probabilities. These were used with the categorical temperature probabilities given by the National Weather Service long-lead forecasts to estimate the forecast load probabilities. In summer an...

AERAs Host Teacher Workshop: Hazardous Weather Conference for Educators

Project ATMOSPHERE atmospheric educational resource agents (AERAs) representing the mid-Atlantic states pooled resources to conduct a regional workshop for teachers. This conference used hazardous weather as its central theme. Over 150 people attended this one-day event held in Richmond, Virginia, which included three concurrent sessions of eight presentations each. The workshop included presentations by meteorologists and educators from the National Oceanic and Atmospheric Administration, Virginia Power, and television stations, as well as the AERAs themselves. The presentations were designed to develop basic understandings about hazardous weather and to provide guidance for establishing hazardous weather emergency action plans for schools. The orientation of the program was hands-on, including a number of activities for teachers to implement in the classroom. This workshop demonstrates how educators and scientists can form partnerships to improve science education.

An AGC implementation for system islanding and restoration conditions

An island AGC function has been implemented in a large-scale power system, Virginia Power Company (VP), to assist in system emergency and restoration situations. It is the first time that the conventional AGC function has been enhanced to be utilized, rather than to be suspended, under such circumstances. The island AGC function is designed to be implemented in both the real-time and the dispatcher training simulator (DTS) environments. The latter provides a realistic closed-loop simulation environment that mimics the real system behavior, offering an excellent opportunity for operators to be well-trained, aware and prepared for abnormal situations. This implementation has been tested on the VP system model, which consists of 4400 buses and 775 generators. It has successfully completed custom factory tests, and it is the user's opinion that the island AGC will provide a valuable additional capability for use during system restoration. >

Combustion System Performance and Field Test Results of the MS7001F Gas Turbine

This paper presents the results of the combustion system test of the MS7001F installed at the Virginia Power Chesterfield station. Tests of water and steam injection for NOx control were performed. Results of emissions, combustor dynamics, and combustor hardware performance are presented. Emissions test results include NOx, CO, unburned hydrocarbons, VOC, and formaldehyde levels. Combustor dynamic activity over a range of diluent injection ratios, and the performance of an actively cooled transition duct are also discussed. Combustion system mechanical performance is described following the first combustion system inspection.

Considerations for higher voltage distribution

The major considerations involving the selection of the voltage level for distribution facilities, principally 25 kV and 35 kV systems are discussed, and Virginia Power's experience with 34.5 kV is highlighted. It is shown that significant savings can be achieved with higher voltage distribution in the cost of plant required per MWh delivered with no sacrifice in reliability. Higher voltage distribution also provides a reduction in energy losses, substation and line construction, thermal problems, operating and maintenance costs, and manpower requirements. Guidelines are suggested for the establishment and the conversion of facilities to a higher distribution voltage for a given area. >

Managing load data at Virginia Power

The use of real-time data and what is referred to as semi-real-time data for asset management is described. The basic premise behind asset management is to utilize existing facilities to full capacity before installing new ones. Facility load data is made readily available to various company departments (such as metering, substation band system protection, budgeting, marketing, system planning, and division planning) as well as system and division operations by tying information networks together. Having access to this data allows unique approaches to reliability and efficiency in serving customers.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Authors

Authors

Forecasting market potential and market penetration of residential water heater load control programs

AbstractThis paper presents a model which estimates market potential and forecasts market penetration for one demand‐side management (DSM) programwater heater load controlin the service territory of Virginia Power Corporation, a large electric utility in the south‐eastern United States. Water heater load control is a voluntary program where customers are paid a monthly incentive to allow the utility to shut off power to their electric water heaters during periods of peak demand. Reducing the level of peak demand through DSM programs is one way for utilities to avoid building new power plants. The current total energy (or demand) impact due to a load control program is the sum of the changes in energy (or demand) for all program participants. The projected energy and demand impact due to a load control program is the average change per participant multiplied by the number of participants or adopters of the program. While it is reasonably straightforward to measure the energy savings resulting from shutting off power to a water heater, the more difficult task for planning purposes is forecasting the number of customers who will actually join the program (i.e. the market penetration) for a given incentive. The customer decision process is divided into three stages: eligibility, awareness, and adoption. The responsiveness of market penetration to changes in advertising and incentive amounts is demonstrated. In addition, the impact of changing advertising and incentive amounts on the percentage of aware customers who adopt the program and on that of eligible customers who become aware of the program is estimated. This model can be used by utility planners and managers to forecast the market penetration of both new and existing load control programs. In addition, it can be employed to estimate the impact of various promotion and marketing schemes on both market potential and market penetration.

Optimization methods for evaluating competitive bids from private producers

Competitive bidding for private power contracts is becoming an important element in utility planning. The use of optimization methods for incorporating nonprice factors into the evaluation process is examined. Using data based on the 1988 Virginia Power solicitation and synthetic estimates of bids, the selection problem is simulated. The utility's announced preference for coal-fired projects is modeled using modifications to assumes fuel and capacity prices. Methodological issued for incorporating nonprice factors in bid evaluation are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Real time T&amp;D applications at Virginia Power

Advances in the automation of the transmission and distribution (T&D) system at Virginia Power in the 1980s are described. Programs such as supervisory control and data acquisition (SCADA) and load management using a two-way automatic control system (TWACS) have reduced system losses and increased the reliability of service to the customer. Inhouse support of SCADA software has provided flexibility to meet the changing operating conditions. The discussion covers CAPCON, a capacitor bank control program which was the first process control application written for the SCADA II machines; automation of load tap changer controls; control sequences, particularly for voltage reduction and emergency load curtailment; emergency isolation of network grids; and TWACS.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>