Power System Analysis, Planning and Operations (PSAPO) Summary of 2008 Products

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1 Power System Analysis, Planning and Operations (PSAPO) Summary of 2008 s Program P TI Description Program on Technology Innovation: Power System Oscillation Detection and Contribution entification Using Wide-Area GPS Synchronized Phasor Measurements P Multiple Uses of Substation Data Program on Technology Innovation: Next Generation Monitoring, P TI Assessment, and Control Program on Technology Innovation: An Investigation of the Stability Region Concept Applied to Stability- P Constrained Optimal Power Flows Competitive Path Analysis Using Mathematical Programs with P Equilibrium Constraints Evaluation of the Effectiveness of Automatic Generation Control (AGC) Alterations for Improved Control with P Significant Wind Generation Evaluation of the Impacts of Wind Generation on HELCO AGC and P System Performance - Phase 2 Situation Awareness in Power System Operations: Guidelines and Recommendations for Supporting P Situation Awareness P Best Practices in State Estimation Next Generation State Estimation P E Workshop Controlled System Separation: Key Issues, Industry Practices and Stateof-the-Art P Technologies Prototyping a Decision Support Tool for Evaluation of System Restoration P Strategy Options P E Workshop on System Restoration entification of Critical Voltage Control Areas and Determination of P Required Reactive Power Reserves Type Manager Date Update Zhang, Guorui 27-Jun-08 Update Myrda, Paul 30-Jun-08 Update Zhang, Pei 22-Jan-09 Update Zhang, Pei 31-Mar-09 Update Update Update Entriken, Robert Brooks, Daniel Brooks, Daniel 30-Mar May May-09 Update Lee, Stephen Ting-Yee 7-Nov-08 Update Min, Liang 1-Dec-08 Resource Min, Liang 14-Oct-08 Update Zhang, Pei 21-Nov-08 Update Zhang, Pei 4-Dec-08 Resource Zhang, Pei 12-Nov-08 Update Zhang, Pei 9-Dec-08

2 Description Type Manager P PCF v1.0 Probabilistic Transmission Congestion and Constraints Forecast, Version 1.0 Software Min, Liang 12-Dec-08 P E Workshop on Probabilistic Planning Resource Min, Liang 19-Aug-08 P P P P P P P P P E P P E P E Grid Shunt Reactive Power Compensation Comprehensive Load Modeling for System Planning Studies Automated Model Validation for Power Plants Using On-Line Disturbance Monitoring Summary of Recommendations from NERC Reliability Readiness Evaluations 2008 CIM-XML Interoperability Including CIM-Based Tools Test The 2008 Transmission Planning Interoperability Test Vision for a Holistic Power Supply and Delivery Chain A Vision of Self-Healing Protection and Control Conduct EPRI CIM/GID WS for general multiple utility audiences EPRI Power System Dynamics Tutorial OTS User Group Meeting and Workshop for Operator Training Conference on ERO Reliability Standards Update Report Report Update Report Report Update Entriken, Robert Brooks, Daniel Pourbeik, Pouyan Lee, Stephen Ting-Yee Becker, David Becker, David Lee, Stephen Ting-Yee Date 26-Nov Mar Mar Oct-08 4-Dec Feb-09 6-Feb-09 Update Zhang, Pei 23-Dec-08 Resource Report Resource Resource Becker, David Zhang, Guorui Zhang, Guorui Lee, Stephen Ting-Yee 23-Sep-08 Delayed 13-Nov Aug-08

3 P Description Type Manager Date Program on Technology Innovation: Power System Oscillation Detection and Contribution entification Using Wide-Area GPS synchronized Phasor Measurements Update Zhang, Guorui 27-Jun-08 Generator and load drops can be detected in real-time with high dynamic accuracy using wide-area frequency measurement systems. This report describes the research and development of a screening tool that can also detect frequency oscillations using the Internet based Frequency Monitoring Network (FNET) and similar systems. It includes analyses of the characteristics of low-frequency oscillations in the time domain and the frequency domain and a preliminary investigation of possible ways of using wide-area measurements to mitigate low-frequency oscillations. Background Frequency perturbations after events like generation trips travel through a power system grid with finite speed and therefore arrive at particular Frequency Disturbance Recorders (FDRs) at different times. The FDRs sample the voltages at different locations; calculate the frequency, angle, and magnitudes of the voltage; and send the data to an Information Management System (IMS) through Internet. Event location algorithms can use data from this system to triangulate the location of an initiating event and estimate its size. It is desired to extend this trigger capability to the detection of oscillations. The oscillations of interest, in general, have a frequency of less than 1-2 Hz. To develop and implement oscillation triggering methods using FNET data To analyze low-frequency oscillations characteristics in the time domain and the frequency domain To make a preliminary study of low-frequency oscillation mitigation The project team adapted an oscillation-screening tool for use in real-time oscillation detection and tested it with field data from the FNET. The tool employs the oscillation envelope method. The team studied low-frequency oscillation in both the time and the frequency domain using simulations and FNET field measurements made during several disturbances in the Eastern Interconnection in They also made a survey of recent literature on lowfrequency oscillation mitigation including some preliminary results on controlling system dynamics by strengthening transmission corridors. This report describes the test results of an oscillation-screening tool using FNET field data. Although the current tool employs the oscillation envelope method, the "sequential peaks" detection method and the fast Fourier transform (FFT) approach may have their merits and should be tested and implemented in future works. The modular approach of the current design should allow multiple oscillation trigger algorithms to be incorporated without major structural changes. In the course of studying low-frequency oscillation characteristics, it was concluded that almost all the inter-area oscillations in the Eastern Interconnection involved a very large number of generators. This finding provides practical information for developing control strategies and guiding the placement of control devices local mode oscillations, not the focus of this study, are typically dominated by one or two machines and are relatively easy to manage locally. With the assistance of wide-area measurements provided by phasor measurement units (PMUs) and FNET, more powerful tools are now at hands to help detect and analyze the oscillations in bulk power systems, discover new phenomena, and develop new control methods for interconnected power grids. From the FNET measurements alone, over 4 years worth of continues system dynamic performance data have been recorded (including frequency, angle, and voltage) in the Eastern Interconnection, WECC and ECORT interconnections. With such wealth of information, it is very likely that all the oscillation patterns or modes are fully characterized and can now be exploited for the design of control and damping systems. For example, with a sufficient number of power system stabilizers (PSS) in any of the 3 systems, wide area control should already be close to reality. The coordination of a group of wide spread power system stabilizers using wide area measurements is well within reach and is a promising area for further research.

4 Description Type Manager Date P Multiple Uses of Substation Data Update Myrda, Paul 30-Jun-08 This report describes a suite of modules developed under the Multiple Uses of Substation Data project. The modules are aimed at the integration and automated analysis of data coming from several Intelligent Electronic Devices (IEDs) such as Digital Protective Relays, Digital Fault Recorders and Circuit Breaker Monitors. Once data are collected, automated analysis processes the files to extract relevant information. The modules convert nonoperational data to information that may be used by variety of applications at Control Center level. The results obtained from the application may be integrated with such utility applications as: Substation Automation, Supervisory Control and Data Acquisition (SCADA), Energy Management System (EMS), Geographic Information System (GIS), Outage Management, Asset Management, and Lightning Detection. IED data are currently used quite differently. Usually data from IEDs are collected manually and then sent to protection engineers for analysis. Often the data are in the original vendors format and can only be displayed using the vendors tool. Integrating data for analysis purposes from several different vendors are used is not straightforward due to the use of different data formats and the fact that different vendors may use different terminology for the same signals and settings in the IEDs. Because of these complications, the process of analyzing data becomes a complex and time consuming job that only a skilful person with lot of experience can do. s developed under this project perform the analysis process automatically, convert data from all devices to a single format, generate reports for each IED type, and fill out a database with processed information, which in turn can be displayed using single visualization tool that makes all information accessible immediately after the occurrence of an event. These applications are aimed at substation groups that consist of protection engineers and maintenance staff, as well as control center groups that consist of dispatchers and operators. Substation groups can be informed about faults immediately and can make quick decisions on responses. Maintenance personnel can be informed about the status of the equipment and any maintenance actions rapidly and without a need to go to the field to perform periodic tests. The control center group can get additional information from IEDs that can improve interpretation of alarms and system restoration procedures. The challenge is to integrate support for these various application tasks across the utility enterprise. The solution requires close collaboration between different utility groups. The objective of this report was to illustrate what is involved in this demanding process and what are the expected benefits once the products are successfully deployed. : The project team demonstrated how the gradual deployment of the modules and proposed applications can work as a cost-effective retrofit strategy. The deployment of the developed modules does not require change in the existing use of the equipment and can be performed without disturbing existing operations. It only requires the addition of processing and communication infrastructure so that the existing data are fully utilized. : The main benefit of this project is to increase the efficiency of the utility personnel responsible for analyzing faults, repairing damaged equipment, and restoring a system. At present, IED data records cannot be efficiently analyzed manually due to the overwhelming number of records captured by devices in the system. Also, use of different vendor specific programs increases personnel training costs due to the distinctively different features and look and feel of different packages. There is slow response if several records supplied by different IEDs for the same event must be uploaded and analyzed. Indeed, it is impossible to efficiently integrate data coming from different IED types and models when different IED systems and services must be integrated. The applications developed in this project make it possible to handle all these tasks more efficiently. : The modules developed in this project, along with modules developed by third parties and integrated with the project modules, may be used to develop a variety of applications supporting protection group, as well as maintenance or operations staff. The core of the applications is customized report generation and conversion of non-operational data to real-time information. Due to competitive market conditions, each utility needs to respond to system disturbances in the most effective possible way. The solution proposed in this report recognizes the value of IED data integration and processing in speeding up the restoration of the system after loss of service. The use of the developed applications and generated information allows utilities to increase the efficiency of their personnel and meet reporting standards imposed by the regulatory and oversight bodies such as FERC and NERC, Inc. : This report attempts to fully utilize IED data recorded at substation level. This development will help utility industry meet many internal and external goals. The internal goals for increased personnel productivity and more reliable system operation are met through introducing automated data processing and integration of operational and non-operational data. The external goals of meeting reporting standards of FERC and NERC, Inc. are met by performing real-time analysis of disturbances and creating comprehensive reports explaining the causeeffect sequences in system operation automatically.

5 P Description Type Manager Date Program on Technology Innovation: Next Generation Monitoring, Assessment, and Control Update Zhang, Pei 22-Jan-09 Power system operation technologies such as computerized one-line diagram visualization, state estimation, contingency analysis, and distance relay were developed upwards of 50 years ago, However, technological advances in communication, computing, and algorithms have made it possible to reexamine methods for performing real-time monitoring, assessment, and control. This report describes the vision, infrastructure, and technology roadmap for future smart control centers. The challenges lie in how to transform the existing control centers in terms of three core functions monitoring, assessment, and control to future smart control centers. The present technologies for these functions have a number of limitations, which prevent flexible, efficient, and sustainable power system operation. The objective of this report is to present a vision of next generation monitoring, assessment, and control technologies and provide a roadmap for achieving that vision in future smart control centers. The proposed vision of next generation monitoring, assessment, and control functions is based on analysis of cutting-edge technology in communication and control. Such an analysis will help ensure that the eventual longterm vision is technologically viable. In developing this report, the authors reviewed key literature on self-healing protection and control systems and the Intelligrid. This report reviews the present monitoring, assessment, and control technologies in power system control centers in detail. Several popular commercial-grade products for self-healing protection and control are briefly examined. The report then describes the vision of the future smart monitoring, assessment, and control functions. That discussion compares the vision with the present technologies and points out technology and infrastructure gaps. Finally, this report presents a roadmap for implementing prospective monitoring, assessment. and control technologies in future smart control centers. The proposed self-healing protection and control framework can improve overall performance of existing protection and control systems. Implementation of the proposed self-healing protection and control framework will reduce the likelihood of cascading failures and will therefore increase system reliability. To implement the self-healing protection and control framework, however, the existing computing and communication infrastructures need to be improved and a variety of technical issues must be resolved through further research and development. The functions of the proposed future smart control centers can be applied to all U.S. power system control centers if implemented correctly, so the value and impact are broad. Future control centers are expected to utilize wide-area information for online, measurement-based security assessment in order to implement an automatic and decentralized control strategy. Hence, the system will be hybrid, integrated, coordinated, supervisory and hierarchical. This vision for future smart control centers is critical to implementing the overall framework of the future smart control grid, also known as the Intelligrid.

6 P Description Type Manager Date Program on Technology Innovation: An Investigation of the Stability Region Concept Applied to Stability-Constrained Optimal Power Flows Update Zhang, Pei 31-Mar-09 This report presents the formulation of optimal power flow with linear dynamic stability constraints. Intensive off-line dynamic simulations were performed to capture the system instability separation modes corresponding to system disturbances and to further derive the linear coefficients for each hyperplane. Optimal power flows with and without the dynamic stability region constraints were computed, and dynamic simulations based on two sets of power flow solutions were performed. Comparison of the two sets of dynamic simulation results shows that the schedules based on optimal power flows with dynamic stability constraints can provide better system transient stability. Current system operations can experience dramatic changes in operating conditions because generation is scheduled using hourly offers. This situation can make it difficult for system operators to assess power system dynamic stability in real time. Usually, system operators assess power system dynamic stability using the available transfer capability (ATC) within transmission corridors or the small-area nomograms that define the local limitations of transmission and generation, and then they reschedule energy delivery to maintain system transient stability. There are two issues with this practical approach. First, both the ATC and the nomograms are generated from offline numerical integration of limited scenarios. They cannot cover the full dynamic stability limitations of an entire control area. Second, the rescheduling actions to move the operating point away from the ATC limits or nomogram boundaries usually are out-of-market actions and may not be cost-efficient. In this research, an OPF problem is proposed to solve the energy-scheduling problem with dynamic stability region constraints that are represented approximately by a set of hyperplanes that defines the space of stable operations. The investigation presents the feasibility of implementation and demonstrates the improvement in system transient stability based on the simulation of dynamic stability region constrained OPF. This research presents the formulation of the optimal power flow problem subject to the dynamic stability region constraints. Exploring a variety of cases demonstrates the effectiveness and benefits of representing the boundary of a dynamic stability region by a set of hyperplanes. Power system dynamic stability is critical for power system operations. Incorporating dynamic stability region constraints into optimal power flow (OPF) applications provides system operators with the energy schedules that allow the system to operate with sustained dynamic stability after disturbances. Using hyperplanes to represent the boundaries of the dynamic stability region makes modeling the dynamic stability region constraints in an OPF problem straightforward. Dynamic simulations based on energy schedules generated by an OPF subject to the dynamic stability region constraints demonstrate verified improvements in system transient stability. This research emphasizes the impact of the dynamic stability region constraints on the energy schedule, and so provides a rapid and preventive method to address power system dynamic stability issue in on-line operations. This method forms the core of an approach that can be applied to electricity market applications. Unlike the optimal power flow with static stability constraints, where the constraints represent the steady-state thermal limits or transmission capability, the optimal power flow with dynamic stability region constraints generates energy schedules that can ensure the transient stability of a system after disturbances. This report demonstrates the application of a dynamic stability region in energy scheduling and proves the sufficiency of representing the dynamic stability region approximately by the hyperplanes.

7 P Description Type Manager Date Competitive Path Analysis Using Mathematical Programs with Equilibrium Constraints Update Entriken, Robert 30-Mar-09 This report extends a proposed method for detecting the potential to manipulate electricity markets in the presence of transmission scarcity. A screening method is used presently in different markets, which relies on cursory measures of transmission scarcity and competitive behavior. The extended method utilizes a Mathematical Program that maximizes profits for combinations of market participants in the presence of potentially scarce transmission resources. This new method incorporates production costs and obeys transmission limitations. As a result, it has the potential to reveal additional information about market competitiveness. Market power is a crucial issue in wholesale electricity markets. Independent System Operators (ISOs) and regulators need tools for identifying bottlenecks that enable the exercise of market power. Once problems with scarcity and concentration of ownership are identified, counter measures can then be devised to mitigate impacts on market prices as well as strengthen market and system operations. The example in this report is taken from a proposal documented by the California ISO. Actual power systems are much more complex, and in practice these calculations are part of critical operations of markets and part of the monitoring tools. Further work on this subject, with additional case studies and efforts to fortify the calculations for large-scale systems, can reveal additional insights into the roles that transmission scarcity and production efficiency play in competitive markets. The most important recipients of these results are market monitors, who are mandated to explore and ensure market competitiveness. A key goal of this report was to enhance the competitive path analysis to utilize equilibrium constraints for market conditions along with profit maximization to extract any possible opportunity to gain from transmission scarcity. The approach is to apply these methods an existing model and proposed technique and explore whether the addition of production cost information and transmission capacity constraints will create additional insights and/or alter the conclusions regarding priorities for mitigation. The goals are largely conclusive, despite potential differences between the models, that the enhanced method produces refined results with slightly different priorities. It also identified new modes of profit making, not found with the proposed method. While the proposed method identifies many potential cases for mitigation, the enhanced technique shows which cases carry more opportunity for profits. The enhanced approach provides a measure of pivotal status of market participants. Rather than based on system configuration and supply/demand information alone, it also reveals possibility of weakness in the transmission network that may be gamed via the strategic bidding. The results could assist Independent System Operators (ISOs) in operating the wholesale electricity market more efficiently. Regulators and system planners may also be benefitted in identifying the key system bottlenecks and prioritize improvements. Applications of competitive path analysis are directly related to mitigation of market power. However, in long time frames, this analysis provides insight into investment incentives and the potential for new investments to ensure competitive trading of electricity across regions. As the practices of national or continental planning become more prominent to properly coordinate energy planning across sectors, the type of economic modeling portrayed in this report will likewise become more prominent for its ability to balance resources across economic sectors and diverse regions. EPRI has pioneered the development and application of market simulation for the study of decision-making associated with electricity markets. While the use of computers to model markets in this way is relatively new, others have used people in similar market experiments for some time. Multi-agent simulation with optimal bidding techniques requires a significant investment of time. Its benefits, however, may be impossible to achieve with other methods. This type of simulation, utilizing fundamental modeling, is currently the best tool for understanding crucial but rarely experienced market phenomena such as energy crises. Its use for investigating market competition reveals details not observable with standard techniques.

8 P Description Type Manager Date Evaluation of the Effectiveness of Automatic Generation Control (AGC) Alterations for Improved Control with Significant Wind Generation Update Brooks, Daniel 26-May-09 Wind power represents a significant fraction of the total generation capacity of the Hawaii Electric Light Company (HELCO) system, and HELCO system operators have observed instances where the short-term variability of the existing wind generation has resulted in increased frequency fluctuations. The existing automatic generation control (AGC) system has sometimes exacerbated these frequency fluctuations. To deal with this problem, HELCO contracted with AREVA to implement functional changes to the existing HELCO AGC as part of an energy management system (EMS) upgrade. The changes implemented by AREVA to the HELCO AGC can be grouped into three basic categories: general tuning of AGC parameters, changes to base AGC code modules, and the introduction of new AGC functions. This report evaluates the impact of wind generation on HELCO s system frequency performance and regulation and assesses the effectiveness of the AREVA AGC modifications in improving system control in the presence of wind generation. HELCO operates as a small isolated grid without the benefits of interconnection to neighboring control areas to provide system support through tie lines during a contingency. As a result, the HELCO system is more susceptible than mainland control areas to a range of negative impacts associated with fluctuations from load and/or generation. HELCO was concerned that with increasing wind penetration levels on the island (an additional 20 MW was scheduled to go online in 2007), the existing AGC would be unable to compensate for the resulting increased frequency fluctuations. The project team compared historical AGC data sets recorded during low- and high-wind generation periods to estimate the impact that wind generation has on HELCO system frequency/ace performance and AGC actions. Two sets of comparisons were made: one for HELCO s base AGC configuration prior to AGC modifications and another for the system after AREVA implemented various changes to its AGC. : While many factors contribute to area control error (ACE) and frequency variations, wind generation is a significant driver. Furthermore, the amount of AGC activity is higher during the high-wind periods for both the preand post-modification data sets. The data show that the general tuning of AGC parameters had the largest impact on AGC performance of any single modification, reducing the total number of control actions and associated MW travel 60-75% relative to the control activity that occurred during high-wind conditions prior to the AGC tuning. An increase in area control error (ACE) and frequency deviation variability accompanied this reduced control activity, however. Other AGC modifications resulted in some increased level of total AGC control activity accompanied by slight to moderate improvements in frequency/ace performance. : Although follow-up analysis conducted on more substantial data sets would validate the current study results, this initial assessment of the impacts of AGC alterations on the HELCO system provided a framework and baseline for ongoing study of the control problems wind generation presents to a generating system as it achieves significant penetration. : For the HELCO system, successful system control is likely to require an increased emphasis on improving the remote control characteristics at the generators themselves: optimizing ramp rates; minimizing time delays; and allowing greater range of control, which may require improvements on the generator control systems. Additionally, engineering expertise will be required at the control center for monitoring and adjustment of both unit and area level AGC parameters to optimize system performance. Even with these actions, the tolerable trade-offs between increased control activity and frequency degradation may limit the amount of wind generation that can be integrated into the system, especially if the wind capacity is concentrated in a common geographic region or single location. To study this problem, additional data analysis was performed in a Phase 2 effort using HELCO system AGC data collected during the summer of 2007, by which time an additional 20 MW of wind generation had become operational at the south end of the Island. This analysis, documented in EPRI report , provides further insight into control/performance tradeoffs under high wind penetrations that could reach as much as 35% of nightly minimum load levels.

9 Description Type Manager Date Evaluation of the Impacts of Wind P Generation on HELCO AGC and Update Brooks, Daniel 26-May-09 System Performance Phase 2 : The Hawaiian Electric Light Company (HELCO) is integrating 33 MW of wind generation into its daily system operations. The percentage of load served by wind generation can at times be as high as 33% and result in serious integration problems for the utility. This project analyzed 819 hours of HELCO automatic generation control (AGC) and frequency performance data in order to quantify the impacts of wind variability on system frequency and AGC control actions and to identify potential mitigation strategies. : HELCO s system operations have directly experienced direct impacts from wind variability. These impacts have included a larger ambient frequency band due to sub-minute variations, large frequency excursions due unexpected sub-hourly (tens of minutes) wind ramps, increased regulating and load following duties on conventional generators, and increased fuel costs associated with maintenance of higher regulating reserves and dispatch of diesel units to arrest frequency excursions. In response to these impacts, HELCO system operations requested this study, which quantifies the technical impacts associated with the integration of existing wind levels into the system and identifies potential mitigating strategies. : The project team conducted statistical analysis and large frequency deviation event analysis 819 hours of 4-second resolution AGC data collected over 36 days from June 5 July 10, : Statistical analysis and large frequency deviation event analysis on HELCO historical operation data support the following conclusions: Wind generation variability for the existing 33 MW of wind generation on the HELCO system degrades frequency performance and increases AGC activity more significantly than load variability. Large wind ramping events can result in large frequency deviation events. The extent to which wind ramps negatively impact system performance depends on the availability of regulating capacity and the time of day that the wind ramp occurs. HELCO system operators are unable to predict wind behavior and accordingly struggle to know the optimal mitigating action to arrest wind related frequency excursions and when to take that action. Dealing with the additional variability of wind generation results in real cost implications for HELCO including increased O&M on regulating units due to the additional duty and more frequent use of quick start diesels to respond to wind-related frequency events. HELCO is already operating at penetration levels of 16-33%. The collected AGC performance data analyzed in this study show that HELCO system operators are struggling to manage the challenges that the 33 MW of wind generation can pose. In order to ensure system security/reliability with the existing wind plant, HELCO should evaluate the cost benefit of obtaining/developing the following operational tools required specifically for dealing with the wind generation challenges: HELCO should continue to pursue advanced short-term wind generation forecasting. The most significant benefit to HELCO s system operation would likely be obtained through improved intra-hour and near-term forecasting of ramp events. HELCO is pursuing research in this area through a project that with a leading commercial forecasting firm. HELCO should investigate whether the increased cost of maintaining higher regulating up reserve margins during periods when wind plants are operating just at or above rated wind speed can be justified on the basis of the improved system security, even though the cost of additional reserves is very high relative to most power systems due to the particular mix of dispatchable generation on the HELCO system. Future wind power contracts in the island power systems should include additional wind power management and control provisions. HELCO should investigate whether existing wind plant operators can be persuaded to use modern turbine control systems more fully to provide MW smoothing, frequency regulation, and/or system inertia to the HELCO grid. HELCO should investigate if supplemental technologies, such as battery storage, can be used to smooth the additional second-to-second variability experienced on the HELCO system as a result of the need to increase the AGC no-control deadband. : Although the recommendations proposed in this study may have economic, technical, or legal drawbacks, these mitigating measures should be considered to ensure system security and reliability for the HELCO system with its current and projected levels of wind generation penetration. : At high penetration levels, the additional variability and uncertainty associated with wind generation does impact AGC activity and frequency performance. Improved short-term forecasting, new technologies, better control systems/methods, and the ability to store energy are expected to aid system operators with wind integration problems in the future.

10 P Description Type Manager Date Situation Awareness in Power System Operations: Guidelines and Recommendations for Supporting Situation Awareness Update Lee, Stephen 07-Nov-08 Recent emphases on situation awareness (SA) in the power industry have highlighted the lack of SA-related research in this domain. New paradigms are needed to guide research and systems design to improve operations by enhancing the SA of operators. This report describes research on three critical topics related to human factors (HF) and SA in the power systems industry: (1) the use of color, (2) the use of automation and its impact on situation awareness, and (3) predictive situation awareness. The objective of this project was to investigate the state of situation awareness in the power systems industry by examining three key areas of human factors and SA in electric power transmission and distribution operations: (1) the use of color in the display of information, (2) the use of automation and its impact on situation awareness, and (3) the use of predictive tools to support the highest levels of situation awareness. A goal for the work was to identify design guidelines and provide recommendations for the three areas that will help to ameliorate effects of the breakdowns in SA that can be found in power systems operations. This project features data collected from site visits with three control centers. Semi-structured interviews and observations guided by specific design criteria were used to collect data on the three critical HF/SA areas identified for the project. An online color survey was also conducted to supplement the site visit data collection. This project represents a detailed study of the use of color, automated systems, and predictive SA tools in the power industry. Data was provided from site visits with three control centers and an online color survey. A total of 27 survey responses from 25 separate EPRI member companies were collected and analyzed. Use of good HF/SA practices as well as gaps were identified for each topic area. Lists of guidelines and recommendations for improving each critical area were developed, with five (5), ten (10), and six (6) specific guidelines provided for the color usage, automation, and predictive SA topics, respectively. It is hoped that the guidelines and recommendations will be used by the power systems industry and software vendors to effect changes in the design of control room displays and advanced applications. EPRI has long conducted research in human factors and man-machine interfaces. With the advent of third-party software applications outside of the major energy management systems, a diversity of innovative visualization techniques has emerged, including different uses of color within graphical user interfaces. EPRI and its members believe that a review is needed to help promote more uniformity and application of sound human factors principles for enhancing operator situation awareness. The results of this project will be presented in a workshop on December 9, 2008 which is open to the utility industry and software vendors. It is hoped that the industry will move towards a usercentered software design philosophy and improve operator situation awareness.

11 Description Type Manager Date P Best Practices in State Estimation Update Min, Liang 01-Dec-08 Power system state estimation has become an essential application in today's energy control centers. The performance of a state estimator depends not only on the solution algorithm and its implementation but also on the existing measurement configuration of the given power system. The future evolution of state estimation, as envisioned in EPRI, will be most affected by new technologies, such as synchronized phasor measurements, as well as by the trend toward decentralization of system operation, monitoring, and control. This technical update covers the results of a survey of electric utilities and a follow-up workshop with survey participants. Survey responses were obtained from ten U.S. and Canadian utilities across a wide spectrum of state estimator users. Responders included transmission operators, balancing authorities, and reliability coordinators. These results will help to shape future planning by identifying the most effective pathways for the future evolution of power system state estimation. Electric utility managers who are responsible for system operation and new technology integration are the intended audience for this report. This technical update is relevant to all types of transmission operators, balancing authorities, and reliability coordinators who use and implement state estimators. As increasing amounts of intermittent renewable generation sources provide power to the grid, as computer capabilities increase, and as the scope of system monitoring expands, state estimators need to improve to continue delivering optimal performance. The next-generation state estimators will be strongly affected by new technologies, such as synchronized phasor measurements, as well as by the trend toward the decentralization of system operation, monitoring, and control. The objective of this project was to identify and highlight the best practices in state estimation and also determine which aspects of state estimation could be further improved and/or revised to suit changing system requirements. This project is based on a survey that contained questions on different aspects of state estimation function. The survey aimed to gather information about the utilization of state estimation function by energy management system (EMS) operators It also investigated the methods used by existing state estimators to carry out various modeling, analysis, and error processing tasks that facilitate successful execution of the state estimation solution. This survey provides data and information on the current best practices in state estimation. As summarized in the report, there has been significant progress made both in the solution algorithm and its implementation, making the state estimator one of the crucial applications in today's energy management systems. Several other applications make use of state estimator output in order to control and manage the system efficiently and reliably. The survey also identifies certain features that are either missing or can be further developed in order to optimize the performance of state estimators. There are extensive areas for future research on future state estimators. Broadly speaking, research should: Help utility members to fully utilize existing or soon to be installed phasor measurement units (PMUs) for state estimation Enhance the state estimator's accuracy, robustness, and performance Enhance the ability of system operators to observe and control the system Forecast the onset of instability by using predictive state estimators EPRI considered it necessary to review existing technologies and the prospects for next-generation state estimators and identify new capabilities that could facilitate power system operation both in terms of reliability and in enabling more efficient operation of power markets.

12 P Description Type Manager Date Controlled System Separation: Key Issues, Industry Practices and State-of-the-Art Technologies Update Zhang, Pei 21-Nov-08 Power systems are increasingly stressed by the rapid growth of electricity markets and renewable sources. As a result, the risks of a disturbance causing out-of-step generators or triggering cascading failures in a power system are also increasing. In extreme situations, successive line trips may break the power network into two or more islands in an undesired manner. For those areas without or lacking of generation capacities to support local electricity demands, much load has to be dropped, thus resulting in blackouts. Controlled system separation (islanding) is an effective resort to mitigate cascading failures and out-of-step conditions. It actively isolates the outage area to save other areas or, according to out-of-step generator groups, splits the power system into designed islands with minimized generation/load imbalances. In this way, loss of load can be reduced to a minimum. This report summarizes the key issues that need to be addressed to implement controlled system separation in a large-scale power system, investigates current industry practices in North America, and introduces state-of-the-art technologies in relevant fields. For a particular power system, the development of a controlled separation strategy is a complicated planning problem. Existing policies and non-technical concerns usually play important roles in designing the strategy. The four types of separation issues listed above need to be prioritized and interpreted according to system characteristics. This multiyear project aims at Documenting industry practices and R&D needs in the area of controlled system separation Introducing potential technologies and tools that can help system planners perform studies relevant to controlled system separation Suggesting feasible R&D directions to improve existing controlled separation strategies or develop more effective strategies, such as online, adaptive separation strategies. Increasing members' knowledge on mitigating cascading and out-of-step generators to prevent blackouts The project team sent out a survey to collect information on industry practices and interests in controlled system separation. After receiving the feedback, the team documented industry practices. The team also summarized relevant state-of-the-art technologies and defined future research directions in controlled system separation. Controlled system separation can effectively stop the spread of cascading and control out-of-step generators to avoid large-area blackouts. To implement controlled system separation in a power grid, four major separation issues need to be addressed: Where to separate the grid? This issue involves the selection of separation points or island boundaries. When to separate the grid? This issue involves the determination of separation timing. How to separate the grid? This issue is about the design and coordination of separation devices. What to do next? This issue is about the frequency and voltage control in each island after separation. This report explains the importance of controlled system separation in mitigating cascading failures and out-of-step generators, and summarizes the key issues that need to be addressed to develop a separation strategy. Industry practices and the state-of-the-art technologies in this area are also documented, thus providing members with an overview of controlled system separation. A major R&D goal in transmission system protection is to avoid cascading failures by using improved special protection schemes. The existing "fixed" system separation in which separation points are pre-determined can be replaced by a more "intelligent" separation scheme in which separation points are determined based on real-time power system conditions. Wide area measurement systems (WAMS), now in development, can gather and process the information needed for controlled system separation. EPRI plans to develop a phasor measurement unit-based separation strategy that integrates appropriate and practical technologies to address key separation issues. Based on this separation strategy, utilities will be able to easily customize their own separation strategies to meet their specific requirements.

13 Program Description Type Manager Date Prototyping a Decision Support P Tool for Evaluation of System Update Zhang, Pei 4-Dec-08 Restoration Strategy Options Power system restoration is well recognized as one of the most important tasks for electric power grids. Following a power outage, dispatchers in the control center work with the field crews to re-establish the generation and transmission systems and then to pick up load and restore service. It is reported that the impact of a blackout increases with the duration of its restoration. Blackout events and aging transmission infrastructures in North America require that greater attention be paid to R&D in system restoration and its associated decision support tools. The purpose of this research is to address the general strategies and online decision support tools for system restoration. A specific restoration plan can be established by a combination of these general strategies based on the system conditions. Needless to say, system reliability depends heavily on the efficiency of system restoration. Unfortunately, few decision support tools are available to dispatchers and restoration planners today. Restoration plans are developed with basic simulation tools for power flow, dynamics, and electromagnetic transients. These plans developed off line are then used as guidelines for dispatchers in an on-line environment. Dispatchers need to adapt to the actual outage scenario and available resources and be able to develop the strategy based on their experience. On the other hand, restoration strategies are closely related to the specific system characteristics. Since one system's situation does not conform readily to the situations of other systems, the restoration strategies cannot be generalized easily. The purpose of this project is to prototype a decision support tool for evaluation of system restoration strategies. In this project, the best practices of the industry are acquired and documented. Then, the necessary computational concepts and tools for evaluation of system restoration strategy options are developed. Industry practice and documentations of system restoration plans were studied in this project. A new concept, generic restoration milestone (GRM) during system restoration, has been proposed. Based on that, a prototype decision support tool for evaluation of system restoration strategy options was developed. A specific restoration strategy can be established by a combination of GRMs based on the system characteristics, energy sources and constraints of power grids, and then be examined by simulations. Different combinations or sequences lead to different strategy options and performances. Simulation studies have shown that the developed decision support tool enables a power system at the blackout status to restart and self-organize various parts until a complete restoration. The following results are documented in this report: Investigated system restoration options and procedures form industry Summarized the common issues on power system restoration Summarized general philosophies of restoration Developed the concept of generic restoration milestone (GRM) that can be used to establish the specific system restoration strategy Developed system restoration strategies based on GRMs Developed a graph theoretic algorithm to finding the shortest path for cranking non-blackstart units or to pick up loads Developed a power flow analysis algorithm with frequency response of generators and loads during restoration process EPRI prototyped a decision support tool based on a new concept, generic restoration milestone (GRM), for large interconnected power grids. A set of flexible generic restoration milestones and the associated algorithms that are able to evaluate different restoration strategy options are used to reconstruct system restoration strategies adopted in industry. The proposed decision support tool will be an operational aid during system restoration. : It is important to develop a decision support tool to assist system planners in system restoration planning and, ultimately, assist system operators in an on-line restoration environment. This research developed a new methodology and prototyped a decision support tool for evaluation of system restoration strategies. It is believed that the proposed methodology represents a major step toward modernization of power system restoration that is largely manual at present.