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PSERC Seminars 2009


Decision Tree Based Online Voltage Security Assessment Using PMU Measurements
With increasing difficulty in approving and installing new transmission lines, modern power systems are operated closer to their limits due to the continuous increase in load demand and generation capacity for the past few decades. Thus, severe contingencies may affect system stability leading to a large-scale blackout such as the one that occurred on August 14th, 2003 in North America. Among the different stability problems, voltage instability is one of the most critical system conditions that threatens system secure operations. This research project presents and examines an online voltage security assessment scheme to evaluate post-contingency voltage security in real time by using synchronized phasor measurement units and periodically updated decision trees. The main objective was to develop a fast and accurate tool to predict whether certain severe contingencies will initiate voltage collapse at the current operating condition for the purpose of preventing voltage collapse in a modern power system. The online assessment results can be used to guide system operators in real-time decision making. This project involved the participation of a PSERC member company ? American Electric Power Corporation ? that provided supplemental funding for the project and the associated data, and participated as an industry advisor to the project.  
Vijay Vittal 05/04/09 580.87 KB PDF 09-01
Advancement in Arc Flash Related Hazard Research and Safety by Design
Arcing faults can cause serious injuries or death through a number of energy transfer mechanisms such as heat, pressure, sound, shrapnel and electromagnetic radiation. Accurately estimating the available thermal energy is one of the most critical aspects of assessing the severity of the arc flash hazard. This presentation will address various aspects of thermal energy exposures, discussing in detail the three categories of incident energy calculations that have been developed: theory based models, statistically developed models, and semi-empirically derived models.  
P.K. Sen 02/02/09 5.58 MB PDF 09-02
Tools for Assessment of Bidding into Electricity Auctions
In many restructured electricity markets, transactions occur through frequently-repeated uniform-price auctions. Such market mechanisms are justified, in part, by theoretical models that suggest these auctions facilitate efficient dispatch and send ?correct? signals for future investment. However, empirical analyses of offers into electricity spot auctions have uncovered evidence that actual offers by some market players can deviate significantly from theoretical models of profit-maximizing offers. This leads to inefficiencies in both balancing and bilateral markets. This project developed a computational tool for analyzing offers into auctions.   
Ross Baldick and Steve Puller 03/03/09 1.56 MB PDF 09-03
Contributions of Climate Science to the Electric Power Industry: Forecasting with Lead Times of Hours to Decades
Variability of weather and climate represents a significant source of risk to the electric power industry. Weather influences power trading, fuel acquisition, load forecasting, systems planning, hazard planning and a range of related tasks within the industry. Lead-times for weather and climate information range from minutes for rapidly changing hazard conditions and wind-power resources to decades for infrastructure planning. Demands on forecast accuracy are equally daunting. A half degree Fahrenheit can mean the difference between normal operation and catastrophic loss of power distribution and transmission due to ice-laden power lines. Similarly, a 1% error in daily wind speed estimates for a 100MW wind generation facility can lead to losses approaching $12,000,000 over the plant lifetime. Current societal calls for changes in fuel sources will bring additional weather and climate related risks for the electric power industry, particularly for use of biofuels, wind, hydropower, and solar. I will provide an overview of the state of the art in mesoscale weather forecasting and regional climate modeling with applications to the electric power industry, including current efforts to reduce limits to predictability. For short-term prediction I will use wind speed forecasting as an example, and for the longer term I will discuss potential impacts of climate change.  
Gene Takle 03/03/09 1.96 MB PDF 09-04
Challenges in Integrating Renewable Sources into the Electric Power Grid: A Power Electronics Perspective
Renewable energy portfolio standards are requiring higher penetration of renewable energy sources in the years ahead. Such large-scale integration of renewable generation sources into the electric power grid is raising critical issues. Many issues are at the system level, such as how to address the variability in output from renewable generation sources. Other issues are at the layer of a generator?s interface to the grid where power electronics is commonly involved either due to the inherent necessity of or for the sake of improved controllability. The critical functionalities carried by power electronics include: 1) provide the necessary voltage and frequency compatibility between the renewable source output and the power grid; 2) optimally control renewable sources for maximized energy yield among other objectives; and 3) provide active and reactive power support to the power grid during normal operation or disturbance events. Coupled with the multi-functionalities are the requirements for a broad operating range, high reliability, and cost effectiveness, which collectively present significant challenges to the design and control of the power electronic interface. This presentation will give a closer look at some of the issues and solutions.  
Bingsen Wang 04/07/09 443.07 KB PDF 09-05
Effects of Ancillary Service Markets on Frequency and Voltage Control Performance of Deregulated Power Systems
Ancillary services are those necessary to sustain the basic operation of power systems provided by generators and transmission control equipment. The focus of the research at Washington State University was on balancing markets, which includes regulation and load following, and secondary voltage control markets. In the project, we: ?Studied the existing frequency and voltage control markets and the measure of control performance ?Identified the attributes that influences control performance of the system and possible improvements ?Analyzed short and long term impacts of market structures on performance. The comparative studies are presented to examine whether existing markets should be changed and exploiting available control options can result in a more desirable performance. In a separate section a method is presented to unify the responsibility of regulation and load following under classical Automatic Generation Control (AGC). The method described here uses the AGC system to dispatch both regulation and load following in real-time. Subsequently, feasibility of a competitive market for load following is discussed. We also studied secondary voltage control. In an attempt to capture the impact of VAr markets and associated secondary voltage control methods on voltage control capability in terms of controllability, performance and economics of the system, two methods of automatic secondary voltage control have been looked into in this work, voltage control by adjusting the reference voltage of generators and voltage control by adjusting the reactive power injection at the generator bus. Feasibility of competitive markets in VAr using the above mentioned generation based voltage control methods have been examined thereafter.  
Anjan Bose, Washington State University 04/20/09 4.75 MB PDF 09-06
Voltage Recovery and Optimal Allocation of VAR Support via Quadratic Power System Modeling and Simulation
Voltage instabilities have been a major increasing concern for power system operations and control. Voltage instabilities occur during system swings, inadequate VAR support, fault induced delayed voltage recovery, etc. Load dynamics is an important contributing factor to voltage instabilities. During a system disturbance these phenomena can lead to protective relaying operations that further aggravate the disturbance. The prognosis of voltage problems and mitigation of voltage instabilities is a complex problem. This talk will describe recent work that resulted in advanced methods for mitigation of voltage related phenomena. The talk will characterize voltage instability phenomena and will present a new approach for advanced simulation methods of voltage-recovery phenomena using improved, realistic system models and accurate solution techniques and mitigation methods for improved voltage recovery. The important issue of load dynamics and their impact on voltage stability is addressed.  
Georgios K. Stefopoulos 05/04/09 1.03 MB PDF 09-07
Improving Economic Dispatch through Transmission Switching: New Opportunities for a Smart Grid
While it is quite common for operators to occasionally open lines that reach their thermal limit, such practices are employed on an ad hoc basis and are not driven by cost considerations. The objective of our work is to explore, from an economic perspective, the potential of treating the grid as a flexible topology that can be co-optimized along with generation dispatch, subject to reliability constraints, so as to minimize the cost of serving load. This talk will review recent work by the authors demonstrating that optimizing the network topology with generation unit commitment and dispatch can significantly improve the economic operations while maintaining the traditional ?N-1 reliability? standard. Our analysis also provides an assessment of potential economic gains from smart grid technologies that will enable of the N-1 reliability standard in favor of new reliability concepts such as ?just in time N-1 reliability?. Test results based on a DC OPF analysis are presented for the IEEE 118 bus model, the IEEE RTS 96 system and the ISO-NE 5000 bus electric grid.  
Shmuel Oren 06/08/09 472.28 KB PDF 09-08
Recent Advances in Electric Energy Conversion and Storage
Power electronics is an innovative and expanding area in electrical engineering. Recent advances in high power devices permit the control and flow of electric energy efficiently. The digital nature of power switching devices makes the control of electric power switching circuits convenient with the use of digital signal processors. Power electronics has widespread applications in today?s industry such as in power supplies, variable speed drives, automotives, marine, etc. In this lecture, I will describe progress in design of various electric machines and power electronics converters for a variety of applications such as wind turbines, high speed flywheel energy storage systems, hybrid electric vehicles, ship propulsion, washing machines, etc.  
Hamid Toliyat 09/01/09 5.00 MB PDF 09-09
Analyzing the System Costs of Wind Variability
Wind power forecast uncertainty raises concerns of the impact of wind power on power system and electricity market operations. This research project uses an optimal power flow (OPF) model in a Monte Carlo Simulation (MCS) framework to estimate the cost impacts from the uncertainty in windfarm output. Using various regional load levels and assumptions on the costs for providing balancing energy, the results from the OPF and MCS analysis show that wind power forecast uncertainty, combined with load forecast uncertainty, can increase production cost for the 39-bus test system up to 350 times, though for most cases the forecast uncertainty does not introduce any significant changes from the base cases. The real and reactive power losses are shown to be higher for scenarios with low wind?high load and high wind?low load as compared to the moderate wind?load cases. The results also show minimal voltage violations across the test system.  
Judy Cardell, Smith College 10/05/09 367.49 KB PDF 09-10
Aggregated Electricity Load Modeling & Control for Regulation and Load Following Ancillary Services
This talk will present new methods to model and control the aggregated power demand from a population of thermostatically controlled loads. The control objective is to produce relatively short time scale responses (hourly to sub-hourly) for ancillary services such as load following and regulation. The control signal is applied by manipulation of temperature set points. The methods leverage the existence of system diversity and use physically-based load models to inform the development of a new theoretical model that accurately predicts ? even when the system is not in equilibrium ? changes in load resulting from changes in thermostat temperature set points. Insight into the transient dynamics that result from set point changes is developed by deriving a new exact solution to a well-known hybrid state aggregated load model. A straightforward minimum variance control law is developed and it is shown that the high frequency components of the output of a wind plant can be followed with very small changes in the nominal thermostat temperature set points.  
Duncan Callaway, UW Berkeley 11/03/09 1.24 MB PDF 09-12
Proactive Planning and Economic Assessment of Transmission Investments
Seminar Slides  
Shmuel Oren, University of California at Berkeley 11/10/09 4.82 MB PDF 09-13
An Engineering and Economic Evaluation of the Impact of Cap-and-Trade for CO2 on Electric Power
Emerging environmental policies to reduce CO2 emissions will raise a number of challenges for the electric power industry as it continues to maintain a reasonably priced and reliable supply of electricity. For instance, the industry faces the likelihood of: ? increased generation from numerous and diverse new energy sources that emit less CO2 (if any) than traditional alternatives ? ever more restrictive caps on CO2 emissions from all generation sources ? increased loads from plug-in hybrids and other forms of energy storage ? wide-ranging demand response programs using smart grid technologies. Besides policies for reducing CO2 emissions, there is the possibility of tighter standards on NOx and SO2 emissions to reduce ozone and fine particulates. Careful analysis of the implications of those environmental policies is warranted because of the effects they could have on retail prices, on the system-wide cost of operation, on reliability, and on emissions of all pollutants. Our study focused on a particular environmental policy: cap-and-trade as proposed for CO2 and is currently applied to NOx and SO2. We use an economic/engineering model of the power system in the northeastern United States as the conceptual framework for analyzing the impact of environmental regulation. In our study, we conducted simulations using a 2007 power system with network reduction to capture both power flows and voltage constraints, thereby enabling ?stress testing? of the current power system.   
Bill Schulze, Cornell Univ. 11/29/09 549.15 KB PDF 09-15
Power System Level Impacts of Plug-In Hybrid Vehicles
Plug-in hybrid electric vehicles (PHEVs) offer an attractive solution to a growing dependence on imported foreign oil, offering potential benefits along with critical issues for the electric power industry. The impact of PHEVs on the power grid was investigated in a PSERC project. The project?s methodology was based on three procedures: (a) typical use of PHEVs incorporating human habits and terrain on which cars are driven for the purpose of evaluating the resulting electric and gas energy consumption; (b) simulation of the electric infrastructure (i.e., distribution systems) and the loading patterns that results from PHEV deployment, including the effects on the expected life of distribution transformers, (c) impact of PHEV deployment on energy resource use in the power grid, and (d) impact of PHEV deployment on power system operation and on the operational security of the power grid. Appropriate models were used to capture the interactions between PHEV?s and the complexities of a power grid and distribution system. This presentation will overview the findings of this PSERC project.  
Sakis Meliopoulos and Tom Overbye 12/18/09 1.82 MB PDF 09-16