DISTRIBUTION SYSTEMS

Preventive Maintenance Using Continuous-Time Semi-Markov Processes

Curtis L. Tomasevicz, Sohrab Asgarpoor

Abstract - A method is presented to determine the amount of preventive maintenance to be performed on equipment in order to maximize availability. The method uses a continuous-time semi-Markov process that assumes equipment can fail due to both deterioration and random occurrences. Preventive maintenance can be performed from working state to prevent deterioration failure. An example is used to demonstrate the method using MATLAB and Maple software. Additional flexibility in equipment modeling using semi-Markov processes is described.

Index – maintenance, equipment availability, power system maintenance, semi-Markov processes.

A Heuristic Approach for Predicting Fault Locations in Distribution Power

Laurentiu Nastac, Anupam A. Thatte

Abstract—The first step in restoring systems after a fault is detected, is determining the fault location. The large number of candidate locations for the fault makes this a complex process. Knowledge based methods have the capability to accomplish this quickly and reliably. In this paper, a heuristic approach has been used to predict potential fault locations. A software tool implements the heuristic rules and a genetic algorithm based search. The implementation and evaluation results of this tool have been presented.

Index Terms—Distribution Power System, Fault Location, Genetic Algorithm, Knowledge Based System

Prediction Of Animal-Related Failures In Overhead Distribution Systems Using Neural Network And Wavelet Transform Techniques

Min Gui, Anil Pahwa, Sanjoy Das

Abstract—Occurrences of faults in overhead distribution systems are a significant factor in distribution system reliability. Prediction of animal-related failures has a practical value since animals cause large number of faults in overhead distribution systems. This paper presents a method to predict weekly animal-related failures in overhead distribution system using neural network and wavelet transform techniques. Discrete wavelet transform is applied to decompose the time series of weekly animal-related failures. Six different Neural Networks are constructed for each decomposed coefficient series. Finally, the output series of six neural networks are combined according to wavelet reconstruction techniques to get final output for the weekly animal-related failure prediction. Simulation results indicate that this combined method displays good performance.

Index Terms— Animal-related failures, discrete wavelet transform, neural network, overhead distribution system

Optimum Maintenance Policy Using Semi-Markov Decision Processes

Curtis L.Tomasevicz, Sohrab Asgarpoor

Abstract - A method is presented to solve for the optimum maintenance policy of repairable power equipment. The approach uses a continuous-time semi-Markov process (SMP) to first find the optimal maintenance rate for maximum availability of the equipment. Then a semi-Markov decision process (SMDP) is utilized to determine whether maintenance should be performed in each deterioration state. The approach uses a model that assumes equipment can fail due to both deterioration and random occurrences. Preventive maintenance can be performed from each working state to prevent deterioration failure. An example is used to demonstrate the method using MATLAB software.

    Index – equipment availability, maintenance, power system maintenance, semi-Markov process, semi-Markov decision process.

Reliability Evaluation and Need Based Storage Assessment for Surety Microgrids

Mallikarjuna R. Vallem, Daryl Jensen, Joydeep Mitra

Abstract— This paper presents a Monte Carlo simulation based approach to estimate the interruption duration distributions at the load buses in a microgrid for the determination of need based storage assessment. Energy limited nature of storage devices is considered for the reliability evaluation. Time variable load and generation profiles have also been incorporated in the method to obtain more practical distributions of interruption durations. The method is demonstrated on a ten bus test system and the results are explained.

Index Terms— Interruption duration distributions, microgrid, Monte Carlo simulation, reliability, storage.

Capacitor Placement Optimization Project

Jesus Romero, Dale H. Harrell, Selim Borekci

Abstract— The Capacitor Placement Optimization Tool (CAPOT) is a software application designed to assist Gulf Power engineers in the effective and efficient distribution of capacitors on distribution lines. The CAPOT application consists of three main parts; a power flow program that finds low voltage buses and/or a low substation power factor, a capacitor placement program that finds the optimal placement and operation of capacitors for effective voltage and reactive power support, the installation costs, and the cost savings associated with reduced line losses, and a GUI (graphical user interface) that helps the user create the text input profile of the system or use an existing input profile, run the power flow and placement program, and view the output files generated by both programs. The project was a success in that it met all initial design requirements as well as finding the most efficient operation of capacitors under different loading conditions.

Index Terms—Capacitors, Economic capacitor placement, Graphical user interface, Load flow analysis.

ELECTRIC MACHINES AND DRIVES

Energy Storage Analysis Of A Fuel Cell Hybrid Vehicle With Constant Force Acceleration Profile

Rajkumar Copparapu, Donald S. Zinger, Anima Bose

Abstract— Batteries commonly cater to the power flows and load leveling in hybrid fuel cell vehicles especially during startup and acceleration. Power provided by the energy storage unit (ESU) need not be constant but can be variable according to the instantaneous power and energy requirement of the vehicle. This paper investigates the design methodology for a combined ultracapacitor and a battery ESU. The acceleration profile of a constant tractive force will be considered compared to constant power. The required masses of the storage elements with the various battery and ultracapacitor characteristics for both the constant force and constant torque cases are discussed.

Index Terms— Battery, Fuel Cell, Hybrid Vehicle, Ultracapacitors

Performance Of Doubly-Fed Induction Machine Wind-Generators During Grid And Wind Disturbances

Murali M Baggu, Badrul H Chowdhury

Abstract— A doubly fed induction generator is under study for application with a wind turbine. The operation of the Doubly Fed Induction Generator (DFIG) under different disturbances namely, response to gradual increase or decrease in wind speeds, sudden change of wind speeds like wind gust and different fault scenarios near and farther to the wind turbine are demonstrated in this paper using the wind model developed by DIgSILENT^® in their PowerFactory software.

Index Terms—Doubly Fed induction Generator (DFIG), wind turbine, pitch control.

An Inexpensive Imbedded Motor Controller Using A Tachometer Feedback

B. Haas, M. Etezadi-Amoli, D. Mcpherson

Abstract—This paper describes a DC motor drive using a pulse width modulated (PWM) signal and tachometer feedback.  The PWM and analog–to-digital capabilities of a microcontroller are used to realize a very inexpensive and efficient controller.  The design of the entire system, as well as PCB layout are explored.  Manufacturing considerations for the entire system are also presented.

Index Terms—DC Motor, low pass filter, PIC microcontroller, PWM

Quadratized Three-Phase Induction Motor Model for Steady-State and Dynamic Analysis

George K Stefopoulos, A. P. Sakis Meliopoulos

Abstract—This paper describes the implementation of a three-phase, phase-domain induction motor model for asymmetric load flow and quasi-steady state analysis. The mathematical model is based on the use of linear and quadratic equations, reducing therefore the system nonlinearity to at most second degree. The model optionally includes slip-dependent rotor parameters, allowing therefore a unified and accurate representation of every possible motor design (NEMA designs A, B, C and D). A parameter estimation methodology is also presented that allows the motor model identification using the slip-torque and slip-current motor characteristic. The estimation procedure and the model performance for both steady-state and dynamic analysis are demonstrated with some simple numerical examples.

Index Terms—Induction motor model, Load flow analysis, Parameter estimation, Quasi-steady-state analysis, Three-phase modeling

ELECTRIC POWER INDUSTRY RESTRUCTURING

The Role Of Private Sector Power Generation In Bangladesh

Sanjoy Dey, Shahidul Islam Khan

Abstract—The demand of electricity is increasing day by day. For economic emancipation and in order to meet the Millennium Development Goals, the electricity growth that is generating more electricity, building more transmission/ distribution capacity, bringing more area/ population under electricity coverage and ensuring more efficient management of these are the essential issues. According to the power sector growth in the country, the country needs new 400 MW power each year to meet the growing demands. Building of this particular infrastructure require large amount of capital and is encountering increasing difficulties to finance the required capacity either through the government budget or even by the international development agencies and financing organizations. But the government of Bangladesh is unable to provide the finance to set up new power plants according to the growing demand. That is why in 1996 the Government of Bangladesh (GOB) has decided to build power plants in private sectors and Independent Power Producers (IPPs) launched their business in Bangladesh. In this paper the brief history of the private sector power plants in Bangladesh, their problems and prospects are discussed.

    Index Terms—Bangladesh, private sector, power generation.

Transmission Management And Planning:The Aftermath Of Turkish Electricity Restructuring

Osman Bulent Tor, Mohammad Shahidehpour

Abstract- The key to enhancing electricity restructuring is to have an adequate competition in the generation sector of power industry. This concept requires a sufficient transmission capacity to support trading in electricity markets, while maintaining the system reliability. However, transmission expansion planning (TEP) for managing adequate transmission capacity is a major challenge which involves uncertainties and risks in restructured electricity environment. This study reviews TEP issues in a general perspective and addresses challenges in Turkey where the liberalization of the electric power industry is underway for establishing a competitive electricity market. A few strategies are proposed in this paper which are directed toward managing the risk in ensuring adequate transmission expansion in Turkey.

    Index Terms—Electricity Restructuring, Economics of Power Systems, Turkey, Transmission Management, Transmission Expansion Planning

Toward The Value-Based Generation Investments And Utilization: Stratum Electricity Market

Zhiyong Wu, Marija Ilic

Abstract—In this paper we model and analyze the dependence of electricity market outcomes on the market structures and rules. Market attributes such as electricity prices and their volatility, profits and revenues by the market participants and system cost are assessed. Of particular concerns are the effects of market structures on the long-term generation investments needed to meet long-term uncertain demand. The paper builds upon an   earlier introduction of electricity market modeling resulting from the dynamics of fundamental market drivers, such as demand, supply and market clearing processes. This approach is employed to model and simulate the outcomes in the short-term spot markets, and compare these with the potential outcomes in a newly proposed Stratum Electricity Market (SEM) structure comprising both spot and long-term sub-markets. The performance of the newly proposed SEM is illustrated using Monte Carlo simulations on a simple power system in which the only uncertainties come from the load forecasts and fuel prices.

    Index Terms—Forward Markets for Electricity, Energy Capacity Markets, Investments, Stratum Electricity Market (SEM).

Electricity Restructuring In India

A. Pahwa, Zuyi Li

Abstract—The electricity industry in India is going through a major change with the Electricity Act-2003 coming into force on June 10, 2003. The Act is stated to be the “distilled wisdom” of a series of commissioned international and national consultancy studies and seminars and conferences held at the all-India level for three years. This paper is an attempt to study the changes going on in the Indian electricity market, its components, salient features, and the challenges that are poised for future development. A brief overview of some electricity markets in other countries is presented and some comparisons are made with the Indian electricity market.

     Index Terms—Availability Based Tariff (ABT), Indian Electricity Act 2003, Generation, Transmission, Distribution

Value-Based Transmission Expansion Planning In Deregulated Market

C. W. Lee, Simon K. K. Ng, J. Zhong

Abstract-- Transmission expansion planning (TEP) has faced a significant change since the deregulation of power systems. It becomes even more complicated due to the conflicting objectives and uncertainties which have been exposed by the power industry restructuring. In this paper, a value-based transmission expansion planning algorithm is proposed. The algorithm makes use of the probability density functions (PDFs) of locational marginal prices (LMPs) to deal with the changes in power flow patterns due to the changes in offering prices set by generation companies.

    Index Terms — deregulation, Monte Carlo simulation, transmission expansion planning, value-based

A Game-Theoretic Approach To Study Strategic Interaction Between Transmission And Generation Expansion Planning

Simon K. K. Ng, C. W. Lee, J. Zhong

Abstract—A game-theoretic approach to study the strategic interaction between transmission expansion planning (TEP) and generation expansion planning (GEP) in a competitive electricity market is proposed. The proposed algorithm consists of three levels of optimization to determine a Nash equilibrium such that a dominant strategy can be found out in an expansion planning game.

Index Terms—Deregulation, Game Theory, Generation Expansion Planning, Transmission Expansion Planning.

Interruptible Load And Demand Response: Worldwide Picture And The Situation In Sweden

Arnold Ng'uni, Le Anh Tuan

Abstract— This paper reports on part of the work which have been carried out by a group of students in Electric Power Engineering, Chalmers University of Technology in Sweden, within the scope of their course on Power Engineering Design Projects during the Spring semester 2006. The project has focused on the investigation of the important roles of interruptible loads in deregulated electricity markets. This paper brings about a survey of the most up-to-date programs on interruptible load programs in various electricity markets in the world, with an emphasis on the situation in Sweden. The programs are generally grouped into two broad categories: “reliability-based” program which operates in response to system contingencies and “market-based” program which is triggered by wholesale market price of electricity. It is also seen that in some markets, interruptible loads are considered as an ancillary service.

     Index Terms— Interruptible loads, demand response, ancillary services, ISO/RTO, deregulated electricity markets.

HVDC Transmission To Facilitate The Electric Energy Market In The US

Kala Meah, Sadrul Ula

Abstract-- US is the largest consumer and importer of energy. The Average cents for coal, natural gas and petroleum for the power plants in the US are 136.1¢, 596.1¢ and 429.4¢ per MMBtu, respectively. Wyoming alone produced 35.6% of total coal in the US and it also has large and increasing natural gas reserves. Both the Western and the Eastern US states pay high prices for electric energy, compared to the Wyoming. Rail road cost from Wyoming for coal transportation is twice than its mine mouth cost. Between 1993 and 2004 electric energy production from natural gas increased from 13% to 18%, even though, natural gas is the most costly fossil fuel for the power plant. This was done as a quick response to the shortage and several blackouts in the Western and the Eastern US. Natural gas-fired power plants could be built in a shorter time frame, where as coal-fired power plants require a long lead time. Long term planning and realistic load forecasting could save huge amounts in fuel cost and add stability and reliability margins in the system. Wyoming is suitable for producing more electric energy from both wind and coal and its geographic location can utilize the opportunity to meet the demands in both the Western and the Eastern US.

     Index Terms-- Electric Energy Market, Wyoming’s Energy, and HVDC Transmission

ELECTRIC POWER MARKETS AND POWER PRICING

Short-Term Price Forecasting For Competitive Electricity Market

Paras Mandal, Tomonobu Senjyu, Naomitsu Urasaki, Toshihisa Funabashi, Anurag K. Srivastava

Abstract—Short-term price forecasting in competitive electricity markets is critical for consumers and producers in planning their operations and managing their price risk. This paper adopts artificial neural network (ANN) model based on similar days methodology in order to forecast weekly electricity prices in the PJM market. To demonstrate the superiority of the proposed model, extensive analysis is conducted using data from the PJM Interconnection. The factors impacting the electricity price forecasting, including time factors, load factors, and historical price factors are discussed. Comparison of forecasting performance of the proposed ANN model with that of forecasts obtained from similar days approach is discussed. The forecasting error is the major concern for forecaster; a lower error indicates a better result. Accumulative error depends on forecasting period (hourly, daily, weekly, monthly, etc.). It will increase for a longer time forecasts. In this paper, the test results obtained by using the proposed ANN provide reliable forecast for weekly price forecasting as the mean absolute percentage error (MAPE) values obtained for the first and last week of February 2006 are 7.66% and 8.88%, respectively. Similarly, MAPE for the second week of January 2006 is obtained as 12.92%. Forecast mean square error (FMSE) and MAPE results obtained through the simulation  show that the proposed ANN model is capable of forecasting locational marginal price (LMP) in the PJM market efficiently.

Index Terms—Competitive power market, artificial neural

network, price forecasting, similar days.

An Attempt To Forecast Price Spikes In Electric Power Markets

Yamilka Baez-Rivera, Bienvenido Rodriguez-Medina, Anurag K. Srivastava

Abstract—Price forecasting has become one of the main focus of electric power market research efforts. Existing price forecasting methods have shown a good ability to forecast normal

electricity prices. However, none of the research efforts have demonstrated to be effective in forecasting price spikes in electric power markets. This paper presents a methodology to forecast

price and spikes using system identification approach and radial basis functions neural networks. The results obtained using PJM interconnection data with mean absolute percentage error

(MAPE) of less than 5% demonstrate the feasibility and accuracy of the proposed method.

Index Terms—Power Markets, Price Forecasting, Price Spikes,

Neural Networks, System Identification.

Impact Of Facts Devices On Transmission Pricing And Loop Flows

Prashanth Duvoor, Koteshwar R Padamati, Sujatha Kotamarty, Anurag K Srivastava

Abstract: Transmission pricing has been an important issue after the power system restructuring and deregulation. Due to competition and to maximize the profit, generation companies

(GENCOs) are looking for technical and economical solution to minimize the transmission cost for power delivery to customers.  FACTS are one such device that provides a solution to a certain

extent. There has been an increased use of the FACTS devices for this purpose as they are effective means of controlling the path of flow of power, thereby reducing problems such as loop flows. In

this paper, a 9-bus power system is simulated in Matlab/Simulink to demonstrate the impact of the FACTS devices on the transmission pricing as well on the loop flows. Paper also

presents a study done on the dynamic performance of FACTS devices.

Index Terms— FACTS, UPFC, Loop flows, Transmission

pricing, Deregulation

A Novel Model For Congestion Management Based On Ora-Based Decentralized Optimization

Kai Liu, Yixin Ni, Felix F. Wu

Abstract— The paper proposed a novel decentralized approach for congestion management via Optimal Resource Allocation (ORA) for the forward markets. The available capacities of possible congested transmission lines are considered as commonly shared resources for bilateral and multilateral transactions in the market. Each transaction maximizes its profit using limited capacity of  transmission line capacity allocated by the ISO. Through the proposed decentralized optimization algorithms, the ISO searches the optimal allocation of the capacities of congested transmission lines to the individual transactions and finally the same market efficiency (social welfare) as centralized optimization is achieved. This decentralized approach is more suitable for power market environment since it does not require private and sensitive information submission from individual transactions and the resource allocation decision is always feasible during iterations. The mathematical model, calculation procedure and relevant proof are presented. The computer test results from the IEEE 30 bus system show clearly the effectiveness of the approach and its consistency with the centralized optimization.

Index Terms— power market; congestion management; optimal power flow; optimal resource allocation

A Maximum Quantity Formulation Of The Cournot Game For ISO/Pool Operation

Carl J. Spezia, Constantine J. Hatziadoniu

Abstract—This paper studies the economic equilibrium power pool with aggregated demand, Cournot generators and an independent system operator with no secondary market for transmission capacity.  The independent system operator manages congestion by attempting to deliver maximum quantity at least cost.  The paper formulates a non-cooperative game between suppliers as a maximum total quantity problem subject to network flow constraints and supplier first order profit maximizing conditions.  The paper shows that unconstrainted solutions to the proposed formulation are Nash equilibriums and supplier profits are mutually maximized.  Numerical examples demonstrate a supplier selection policy that is based on their contributions to network flows.  This policy will drive the network to the maximum quantity solution without further intervention.

Index Terms—Game theory, Mathematical programming, Power system economics, Congestion management.

Oligopolistic Electricity Market Competition With Forward Expectations

1. Vidales-Vazquez, G Guitierrez-Alcaraz

Abstract—This paper studies Generation Companies (GENCOs) production decisions in ologopolistic electricity market. The model presented is based upon static equilibrium model solved sequentially. The main idea is to imagine the firms to be in a discrete time situation. The effect of technical constraints, such as time on/off, ramp up/down, startup cost and shut down cost, are not included in the model.

    Index Terms—Electricity Market, Market Equilibrium, Ologopolistic Competition.            

MODELING ISSUES

SOFC Emulation Using Computer Controlled Dc Motor/Generator Set

M. Soliman, A. K. Puppala, M. Safiuddin

Abstract- A dynamic and steady state model of the Solid Oxide Fuel Cell (SOFC) is presented. Simulation results are shown. A laboratory prototype of the fuel cell is built. Both the dynamic and steady state results of the experimental model are verified with those obtained from simulation and show a close agreement with it. The proposed experimental model was designed to be connected to the grid as well as to supply isolated loads.

The proposed model uses a dc motor as the prime mover for a separately excited dc generator, which represents the fuel cell. The fuel cell current and voltage are measured using a National Instruments (NI) data acquisition card and the control signal is fed back to change the generator’s field current.

Index Terms- Combined heat and power (CHP), Distributed Generation (DG), Fuel cell, Solid Oxide Fuel Cell (SOFC).

Hysterisis Modelling By Inspection

Fabian M. Uriarte

Abstract—By looking at the hysterisis loop of a core, its non-linear magnetizing branch can be modeled by visual inspection.  Three constants on the hysterisis loop reveal enough information about the core loss and non-linear inductance that power measurements and data-pairs can be avoided.  An experimental hysterisis loop is taken from a CT and its model put together by visual inspection.  The visual method presented is simulated and verified against an experimental hysterisis loop using SimPowerSystems as the circuit simulator.

     Index Terms— core, current, model, equation, hysterisis, loop, magnetizing, saturable, simpower, simulink, transformer, visual.

Fourier-Series Models Of DC-DC Converters

F. Mişoc, M. M. Morcos, J. Lookadoo

Abstract -- The paper presents new models of DC–DC converters. The sub-circuit formed by the voltage source, switching transistor, and diode, is replaced by an independent square-pulse current source, while the rest of the circuit remains unchanged. Using Fourier series representation of current-pulse square wave, the current source is describe as a sum of sinusoidal currents, thus the system is considered linear. The system’s state-space representations in the time domain and s-domain are de[2]rived. Comparison of the buck converter state-space representation of both models is performed. Numerical validation of the buck converter is presented. The Fourier series models developed in the paper offer the benefits of large-signal models and small-signal models combined, without sacrificing accuracy, and is well suited for transient analysis of power systems incorporating DC–DC converters.

    Index Terms -- Circuit modeling, DC–DC power conversion, Fourier series, linear systems.

Diakoptics In Shipboard Power System Simulation

Fabian M. Uriarte, Karen L. Butler-Purry

Abstract—a partitioning scheme for transient simulation of shipboard power systems (SPS) is presented.  Using diakoptics, the piecewise transient solution to a ungrounded AC-radial (3φ) ring-bus system is found.  Cable tie-lines (floating π-segments) on the SPS ring are converted to hexagon equivalents by discretization and decoupled via source-transportation, diakoptics, and exploiting mutual-susceptance links.  Transient simulation results from circuit simulation (as a whole) and via diakoptics (piecewise) are compared and discussed.

     Index Terms—bus, cable, diakoptics, hexagon, Kron, matlab, partition, power, ring, simpowersystems, system, simulation, shipboard, vtb.

Network Reduction And Time-Domain Simulation Approaches For Increased System Security

R. Arunachalam, R. Singh,B. A. Mork , L. J. Bohmann, and D. Ishchenko

Abstract—Recent blackouts have shown that system swings have a critical effect on the operation of protective relays.  The common method of investigating system swings and their effect on relays is to use a stability program and determine the effective impedance seen by the relay.  Unfortunately, it is difficult to test a relay scheme with the resulting impedance trajectory.  The inputs to relays are voltage and current waveforms, not voltage and current phasors or impedances.  This paper describes a method for generating the voltage and current waveforms associated with system swings.  A transients simulation program, ATP-EMTP, is used with support from a stability program, PSS/E, to produce a reduced system model for simulation of the voltage and current waveforms while retaining the machine dynamics of interest.  The first part of the paper will describe the differences in the modeling assumptions of the two programs and how to translate the modeling assumptions of one program to those of the other.  The second part presents an example of a four machine, two-area system, reduced to a two machine, two-area system.

     Index Terms—ATP-EMTP, Dynamic Reduction, Power System Stability, PSS/E.

EN-TASK: Energy Temporal And Structural Kit

Marija D. Ilic

Abstract—This paper concerns a novel modeling and software framework in support of future electricity and energy services.   A broad vision for one such possible framework named Energy-Temporal and Structural Kit (EN-TASK) is described. It is explained why is this needed, and how would such framework facilitate Dynamic Energy Control Protocols (DECPs) of the future.  The emphasis is on a framework which zooms in and out to assess potential of candidate technology and /or organizational change at the level where it matters the most.

Index Terms—National Energy Model System (NEMS), Electric Power Grid Modernization, Performance Index, Dynamic Energy Control Protocols (DECPs), Distributed Generation (DG), Demand Side Response, Power Flow Control, Storage, Renewable Technologies, Electricity Service, Energy Service.

POWER ELECTRONICS

Nonlinear Robust Control Of Cuk Converter Using Radial Basis Functions

Peda Medagam, Farzad Pourboghrat

In this paper a nonlinear robust control law based on the Successive Approximation of Generalized Hamilton- Jacobi-Issacs (GHJI) equation is proposed for the Cuk converter. The cost function of GHJI equation is estimated by using Radial Basis Functions (RBF). The proposed control law stabilizes the system and guarantees a constant output voltage in spite of disturbances in input voltage and output load. Computer simulation shows the robustness of the control system.

A Novel B-Shaped L-Type Transformerless Hybrid Active Power Filter In Three-Phase Four-Wire Systems

Chi-Seng Lam, Man-Chung Wong

Abstract—This paper presents a novel b-shaped L-type transformerless hybrid active power filter (HAPF) for reactive power, current harmonics and neutral current compensation in

three-phase four-wire distribution power system. The passive filter (PF) is tuned to compensate the dominant harmonic current and also reactive power of the load, while the active power filter

(APF) compensates the remaining harmonic and reactive powervalues. With appropriate design of the system parameters, the novel HAPF topology can prevent most of the fundamental voltage

and current across the APF. This results in a great reduction of the APF’s VA rating, but without significantly deteriorates the system compensation capability. Moreover, transformerless HAPF

benefits by eliminating the transformer phase shift, voltage drop, harmonics loss, bulky size and expensive cost. As a result, the proposed HAPF is characterized by small APF capacity,

economical cost, well filtering effect and easy realization. And it is suitable to be implemented in high voltage and current conditions. A DC-link power flow controller is also employed to uniform its

voltage level. Finally, simulation results are given to verify the viability and effectiveness of the novel HAPF.

     Index Terms—Power electronics, power quality.

A Three-Phase Soft Switching Rectifier Based On A ZCS Zeta Converter

Kai Wan, Mehdi Ferdowsi

Abstract—A new three-phase high power factor rectifier based on Zeta converter is presented. A resonant inductor and capacitor are added to the circuit to create zero-current switching condition for the switch. The circuit is operated in the PWM mode by putting a parallel switch and diode in series with the resonant capacitor. Different operating modes of the new topology are presented in detail. The simulation results verify the analysis.

Index Terms— Soft switching PWM; Three-phase PFC; Zero-current switching

POWER QUALITY

Power Quality Analysis At An Energy Facility

2. Chatham, M. M. Morcos

Abstract--A power quality investigation and analysis for an energy facility are presented.  The energy facility has been experiencing problems with uninterruptible power supplies and 24 V dc power supplies for their distributed control system due to the start-up of the generators.  Power quality monitors were installed at various locations throughout the facility. The results and recommendations from the analysis are documented.

Some Techniques for the Analysis and Visualization of Time-varying Waveform Distortions

J. Xu, N.Senroy, S. Suryanarayanan, P. Ribeiro

Abstract—The time-varying nature of waveform distortions requires a precise analytical tool that is essential in power quality analysis. The time-frequency representation (TFR) provides a powerful method for identification of the time-varying nature of the waveform distortions. The paper presents a comparative study on four techniques for analysis and visualization of waveform distortions with time-varying amplitudes. The techniques include the traditional fast Fourier transform (FFT) and three TFR techniques, which are the Short Time Fourier Transform (STFT), the Discrete Wavelet Transform (DWT), and the S-Transform.

Index Terms—Fast Fourier transform, power quality, S-Transform, Short Time Fourier Transform, time-varying waveform distortions, Wavelet Transform

Overview Of Electromagnetic Interference

Roy T. Albertson IV, Joseph Arthur, M. H. Rashid

Abstract-- The problem of, testing for, and solutions to electromagnetic interference are introduced and analyzed.  The industry direction is looked at for explanation of techniques and ideas.  These topics were gathered through research.  The principal results are that electromagnetic interference is growing because of technological advances in electronic devices and communication demands.  The solutions to this problem are effective and need to be implemented in order to reduce the occurrence of electromagnetic interference.

Index Terms -- Anechoic chambers, electromagnetic compatibility, electromagnetic interference.

POWER SYSTEM ANALYSIS/COMPUTATION

PSO-Based Multi-Criteria Economic Dispatch Considering Wind Power Penetration Subject To Dispatcher’s Attitude

Lingfeng Wang, Chanan Singh

Abstract—Significant attention has been paid to the renewable energy resources such as wind power in recent years. It has potential benefits in curbing emissions and reducing the consumption of irreplaceable fuel reserves. However, the penetration of wind power into traditional fuel-based generation systems will also have some implications such as security concerns due to its unpredictable nature. Thus, in economic power dispatch with wind power penetration, a reasonable tradeoff between system risk and operational cost is desired. In this paper, a bi-objective economic dispatch problem considering wind penetration is formulated, which treats economic and security impacts as conflicting objectives. Different fuzzy membership functions are used to reflect the dispatcher’s attitude toward the wind power penetration. A modified multi-objective particle swarm optimization (MOPSO) algorithm is adopted to develop a power dispatch scheme which is able to achieve compromise between economic and security requirements. Numerical simulations including sensitivity analysis are reported based on a typical IEEE test power system to show the validity and applicability of the proposed approach.

Transmission Corridor Analysis Using PTDFS

David J. Maggio, Thomas J. Overbye, Minghai Liu

Abstract—Subsection 1221(a) of the Energy Policy Act of 2005 calls for a study to determine national interest electric transmission corridors.  These corridors are defined as “any geographic area experiencing electric transmission capacity constraints or congestion that adversely affects consumers.”  This paper presents a method to define a “direct flow” between two hubs using the power transfer distribution factors (PTDFs).  With these hubs properly defined, the hope is to be able to assess where these transmission corridors of national significance exist.

Index Terms—Transmission corridors, Power Transfer Distribution Factors

SVC And TCSC Implemented Into A Newton-Type Harmonic Power Flow Algorithm

J.J. Chavez, A. Ramirez

Abstract—The methodology for including generators as PV buses in a Newton-Type Harmonic Power Flow (HPF) program presented in a previous paper is extended here to include electronic devices. Application examples including a Static VAR Compensator (SVC) and a Thyristor Controlled Series Compensator (TCSC) are presented. Although the calculation of the firing angles for such devices needs an internal iterative procedure, in the overall the HPF methodology does not require an iterative procedure for satisfying the generator constraints and, as a consequence, it nearly preserves the quadratic convergence characteristics of the Newton approach.

Index Terms— Harmonic analysis, Harmonic Power Flow, Newton-Raphson method, Static VAR compensator, and Thyristor Controlled Series Compensator.

Approximate Prediction Of Generator Dynamic Coupling Using Load Flow Data

Jason A. Taylor, Kent A. Sayler, S. Mark Halpin

Abstract—Dynamic coupling occurs when multiple groups of strongly connected generators are tied together through weak or strained transmission lines. Establishing which machines in a system are dynamically coupled has shown to be helpful in identifying coherent area for aggregation, providing insights into system stability, as well as indications of potential stability limits. One of the most significant factors influencing dynamic coupling is the value of the transfer impedance between the machines. Therefore, this paper proposes that a strong indicator of which machines are likely to be electrically coupled can be derived from direct evaluation of the off-diagonal entries of the system impedance matrix. Estimation of the dynamic coupling in this manner not only has the benefit of only requiring readily available machine and load flow data but being computationally simple.

Index Terms—Power system dynamic stability, power systems, power transmission planning.

Highly Available Distributed RAM HADRAM) For Data Exchange Between Power Utilities

Damian Cieslicki, Stefan Schäckeler, Thomas Schwarz

Abstract-Power Control Centers need to model their systems in real-time to support the necessary control and security functions. Neighboring independent system operators and regional transmission organizations also need to exchange system data. In the USA, a data exchange structure based on EPRI’s common information model and XML is evolving.  Currently, this data exchange is implemented by providing each local provider with an agent that mediates between data exchange messages and the local database.   We propose here a different technology for data exchange built of main memory of commodity computers at different independent system operators to provide a universally accessible database.   While distributed memory offers scalability and excellent access times (compared to disk based systems), it is also vulnerable to node outages. Our proposal, Highly Available Distributed RAM (HADRAM) is highly reliable and has the speed and bandwidth advantages of distributed memory.  This enables it to be used as a standard for the timely exchange of system models and real time SCADA data between power utilities.

Index Terms-data communication, data management, distributed random access memory, erasure correcting codes, in-memory-databases, network data exchange, power system control, power system modeling, scalable distributed data structure, transmission control.

Laplacian Structure In Power Network Constraints And Inherent Zonal Price Regions

Daniel Chéverez-González, Christopher L. DeMarco

Abstract—Standard computations reveal that locational marginal prices (LMPs), being Lagrange multipliers in an optimization problem, must lie in the null space of a Jacobian matrix associated with power flow and line flow limit constraints in a power network.  When no line limits are active, the matrix in question has a nearly Laplacian structure, and must admit a vector of all equal elements in its null space (verifying the well-known equal incremental cost condition – that all LMPs must be equal in a lossless, unconstrained system).  When line flow limits are active, the null space grows in dimension, and admissible LMP vectors can show patterns in which buses partition into regions of approximately equal LMPs.  We claim that this phenomena arises from the same near-Laplacian structure in the power flow Jacobian that gives rise to coherency in electromechanical dynamics.  For coherency problems, Fiedler vector computations have been previously exploited for graph partitioning to identify coherent buses.  Using similar concepts, this paper will explore a new computational approach to identifying network partitions in LMP computations, giving rise to “inherent” zonal price regions.

Index Terms—Locational Marginal Prices (LMPs), Zonal Prices, Fiedler vector, coherency.

Basic Frequency and Time Domain Least Squares Methods for System Identification

Ashish Subramanian, John W. Pierre

Abstract—This paper investigates the feasibility of applying least squares (LS) techniques for estimating the low-frequency electromechanical modes of a power system. The performance of time domain least squares (TDLS) and frequency domain least squares (FDLS) system identification algorithms is studied.  These algorithms use measured input and output signals to estimate system models.  Simulation studies are performed.  These simulations include using a test system model developed based on a series of tests performed on the Western North American Power Grid (WNAPG)  in June, 2000.

Index Terms—Least squares, Estimation, System identification, Power system modeling.

Modified Methodology for Tracing Power Flow

Ashutosh Tiwari, V. Ajjarapu

Abstract— Due to continuing trend towards deregulation and unbundling of transmission services, usage allocation has become critical. It is important to determine load being supplied from a particular generator. We need to know in a transmission line, the proportion of power going to a given load and the loads contribution to overall system losses. Thus, tracing method is used to trace the flow of electricity in a meshed electrical network. In this paper a modified methodology is proposed for tracing reactive power flow without adding fictitious nodes on system lines. Also, in this paper a modified methodology is proposed to break down the total real and reactive power loss in a transmission line into components to be allocated to individual loads.

Index Terms— Electricity tracing, Loss allocation

POWER SYSTEM CONTROLS

Neural-Based Predictive Control Applied To FACTS Devices

Ruben Tapia O., Pavel Zuñiga H., Juan M. Ramirez

Abstract-- In this paper applications are presented employing the neural-based predictive control (NPC) for controlling Flexible AC Transmission Systems (FACTS) devices with the purpose of regulating: bus voltage magnitudes through the use of a Static Compensator (STATCOM), and the active power flow on a transmission line where a Static Synchronous Series Compensator (SSSC) is embedded. Contrary to a Proportional-Integral (PI) conventional control with its trial-and error tuning, once trained a neural net able to predict the firing angle, simple calculations are required to achieve the wanted regulation. Thus, the NPC is a convenient tool to execute the power system adaptive control, with the possibility of carrying out such tasks considering non-linearities. The controller's design simplicity and its performance compared with the conventional PI controller are shown, especially those related with overshoots and control signals quality, impacting directly into the controlled variable response and having softer behavior than that of the PI control. The applicability of the proposition is studied by digital simulation.

Index Terms-- Neuro-controller; Power electronic; Predictive control.

An Overview Of Fuzzy Logic Based Power System Stabilizers

Mohamed M. Osman

Abstract - Fuzzy logic has emerged as a promising tool for several power system applications.  A large body of the literature in this area is concerned with the stability of the electric power system, and considerable effort has been directed to the development of a fuzzy logic based power system stabilizer (FLPSS). The purpose of this paper is to present an overview of the FLPSS, based on published literature from 1989 to the present. 

    Index Terms - fuzzy logic, power system stabilizer, power system stability.

A Comparison Between The UPFC And The IPFC In Optimal Power Flow Control And Power Flow Regulation

Jun Zhang, Akihiko Yokoyama

Abstract—This paper presents a comparison study between the applications of the unified power flow controller (UPFC) and the interline power flow controller (IPFC) in optimal power flow (OPF) control. The power injection models of the flexible AC transmission systems (FACTS) devices are reviewed and incorporated in the OPF problem without active power generation redispatching, which minimizes the overall generating cost. The FACTS devices are planned for power flow regulation and their additional degrees of freedom act as additional potential in optimizing the power system. The performance of the UPFC and the IPFC is compared from the viewpoint of the total active power losses and their necessary capacities through numerical examples. The feasibility of a gradient-based algorithm, namely sequential quadratic programming (SQP), is tested, and the importance and some techniques of proper selection of the initial optimization conditions are also presented.

Index Terms—FACTS, IPFC, OPF, UPFC

ADALINE Network Based Adaptive Controller For STATCOM

A. Albakkar, O.P. Malik, W. Rosehart

Abstract— In this paper, an adaptive controller for Static Synchronous Compensator (STATCOM) is developed to damp oscillations and enhance the stability of power systems. The adaptive controller consists of an on-line identified system model and a Pole-Shift (PS) feedback controller. Adaptive Linear Element Neuron (ADALINE) is used for on-line model identification to obtain a dynamic equivalent model of the system. The PS controller is then adapted using the identified model. The proposed technique is tested on a single machine infinite bus system. The results obtained demonstrate improvement in the overall system damping characteristics applying the proposed adaptive controller and enhancing the stability of the power system in comparison to the conventional controller.

Index Terms—ADALINE Network, Adaptive PS Controller, STATCOM.

Nonlinear Robust Adaptive Control Design For DC Power Modulation In Multi-Area AC/DC Power Systems

Kenny K.Y. Poon, H.J. Zhu, Z.X. Cai, Z. Lan, D.Q. Gan, Y.X. Ni

Abstract—A nonlinear robust adaptive controller for dc power modulation of interconnected ac/dc power systems is proposed and is used to damp tie line power oscillations in interconnected power systems. The design idea is to drive the centers of inertia (COI) of various interconnected areas to a stable equilibrium point such that the oscillations in the system can be damped out. Genetic algorithm is applied to optimize the parameters of the proposed controller, and computer test results illustrate that the proposed controller is superior to the conventional linear dc power modulation controller..

Index Terms—Center of Inertia, Genetic Algorithm, HVDC transmission, Nonlinear robust adaptive control, Power system.

Damping Control By Fusion Of Reinforcement Learning And Control Lyapunov

Mevludin Glavic, Damien Ernst, Louis Wehenkel

Abstract—The main idea behind the concept, proposed in the paper, is the opportunity to make control systems with increased capabilities by synergetic fusion of the domain-specific knowledge and the methodologies from control theory and artificial intelligence. The particular approach considered combines Control Lyapunov Functions (CLF), a constructive control technique, and Reinforcement Learning (RL) in attempt to optimize a mix of system stability and performance. Two control schemes are proposed and the capabilities of the resulting controllers are illustrated on a control problem involving a Thyristor Controlled Series Capacitor (TCSC) for damping oscillations in a four-machine power system.

     Index Terms — Reinforcement learning, Control Lyapunov functions, Power system damping control.

POWER SYSTEM EDUCATION

Basics Of Energy Systems Through Games

Varano M., Patel M., Asnani D., TsyKalyuk A., Idowu P.

Abstract—Energy topics have remained dominant in the political arena in the United States since September 11, 2001 and various energy policy statements have been focused on the need for research and development.  To effectively engage and attract undergraduate students to studies in energy however, the structure of presentation of energy information and learning must be expanded.  This paper presents two learning games - “Who Wants to be an Engineer?” and “Energy Jeopardy” that are designed to capture the interest of undergraduates as they are introduced to various topics on electric energy systems.

Index Terms—Engineering education, Energy, Games.

Electrical Safety Education In An Undergraduate Engineering Program: Curriculum Development And Assessment

Ravel F. Ammerman, P.K. Sen

Abstract—In an effort to develop increased safety awareness related to the electric power industry, Colorado School of Mines (CSM), electrical specialty students are required to take a one-week intensive electrical safety training course.  Though safety training should start with young people, it is also an important part of the education for experienced electrical technical personnel too. Engineers, designers, and operators continue to develop insights about electrical safety throughout their careers. This paper discusses the Electrical Safety Training course curriculum developed at CSM and provides an assessment of the effectiveness of the program.  Based on the success of the program this has become a permanent part of the Field Session curriculum.

     Index Terms—Curriculum development and assessment, electrical safety awareness, engineering standards, power engineering education.

On VA's, VAR's, And Other Traditions In Electric Power Engineering

Charles A. Gross

ABSTRACT---The author presents a commentary on traditionally accepted power concepts in classical electric power engineering.  A revision of traditional terminology is proposed.

Enhancement Of Undergraduate Electric Power Courses Via Commercial Electromagnetic Simulation Software

Walter L. Collett

Abstract—The electric power courses at Western Kentucky University emphasize proficiency in both electric machines and the integration of these machines into complex systems via transmission lines. The electric machines considered are electromagnetic devices governed by abstract principles. Recently, the courses have been enhanced by the use of commercial finite element method (FEM) software, which calculates approximate solutions to the governing differential equations and permits visualization and animation to assist in the understanding and design of the devices. This paper will describe how the technology is being used to improve an evolving project-based electric power curriculum.

                Index Terms—finite element method, electromagnetic, machines

POWER SYSTEM MEASUREMENTS AND STATE ESTIMATION

Innovative Sensory Concepts For Power Systems

Jonathan W. Stahlhut, Gerald T. Heydt, Elias Kyriakides

Abstract:  This paper addresses the use of innovative and unconventional instrumentation technologies for power systems.  The main focus is on giant magnetoresistance, Faraday and Poeckels and other optical effect devices, Hall effect devices, satellite measurement technologies, mechanical measurements, lab on a chip / chemical sensing, and video technologies.  It is suggested to utilize overhead conductor mechanical and thermal measurements to provide corrections for state estimation applications.

     Index Terms:  sensors, instrumentation, power system measurements, voltage, current, power.

On-Line Monitoring Of Sag In Overhead Transmission Lines With Leveled Spans

Poorani Ramachandran, Vijay Vittal

Abstract—A method for real time monitoring of overhead transmission line sags has been proposed. Mechanical state estimation is used to determine the sag value of each span of the transmission line using real time data.  Use of separate tension sensors for critical spans enhances the sag estimation process. The estimated sag values can be used to calculate the clearance values to check for compliance with the national electric safety code (NESC). 

Index Terms— Conductor sag, state estimation, overhead conductor, available transfer capacity, tension, ruling span.

State Estimation Of Power System With UPFC Using Interior Point WLAV Method

C. Rakpenthai, S. Premrudeepreechacharn, S. Uatrongjit, N.R. Watson

Abstract--This paper presents a robust state estimator for power system containing unified power flow controller. The state estimation problem is formulated as an optimization problem using weighted least absolute value criteria, with a set of equality and inequality constraints. The interior point optimization method is applied to primal and dual formulation in order to solve this problem. The modified IEEE 14-bus system is used to demonstrate the effectiveness of the proposed algorithm. The simulation results indicate that the method yields good estimation of the system states for a power system with UPFC.

Index Terms—Flexible ac transmission system devices, interior point method, state estimation, unified power flow controllers.

A Kalman Filter Approach To Quasi-Static State Estimation In Power Systems

Ellery A. Blood, Marija D. Ilić, Jovan Ilić, Bruce H. Krogh

Abstract—Static state estimation in electric power systems is normally accomplished without the use of time-history data. This paper presents preliminary work on the use of the discrete-time Kalman filter to incorporate time history into the state estimators. Transitional state equations are derived via linearization of the power flow equations.  A simplified example using a decoupled real power flow solution demonstrates this technique.

Index Terms—Kalman Filter, Electric Power System, Static State Estimation, Time History

POWER SYSTEM OPERATIONS AND SCHEDULING

A Genetic Algorithm Approach To Price-Based Unit Commitment

Jignesh Solanki, Sarika Khushalani, Anurag Srivastava

Abstract – Deregulation creates competition amongst generator companies. The generator company objectives are to maximize their profit and to place proper bids in the market. In order to do this they need to determine the schedule and operating points based on the load and price forecasts. The traditional unit commitment problem aims at minimizing the cost of operation subject to fulfillment of demand. However in a deregulated environment the traditional unit commitment objective needs to be changed to maximization of profit with relaxation of the demand fulfillment constraint. This paper applies a genetic algorithm technique to price based unit commitment (PBUC) for GENCO with 3 generators and compares the solution with that obtained by dynamic programming. Proposed algorithm can be extended to ‘n’ number of generators.

Index Terms - Price based unit commitment, genetic algorithm, deregulation, dynamic programming.

A Two-Stage Stochastic Unit Commitment With Electricity Derivatives

V. Siriariyaporn, F. T. Sparrow, D. J. Gotham

Abstract – A unit commitment problem has long been known in the class of short-term functions and decisions, inherited from vertically integrated utility.  In the competitive environment, the problem has become more complicated due to the fact that any action taken will now influence profitability of decision maker such as generation companies, load serving entities, and so forth.  Thus, not only do economic agents face operational risks, but they also need to procure their operations against financial risks from volatility in fuel, contract, and electricity prices. This leads to the evolution of stochastic unit commitment in this paper integrating risk management tools, i.e., electricity derivatives, so as to reduce the impacts from both operational and financial risks in the short run.  The planning model is structured of stochastic mixed-integer program with recourse cost.  A case study will be addressed with preliminary result presenting an improved solution.

Index Terms – stochastic programming, mixed-integer programming, unit commitment, risk management, power portfolio optimization, and power system planning and operation.

Reactive Power Reserve Issues

Pablo A. Ruiz, Peter W. Sauer

Abstract—The lack of investments in transmission and the inductive nature of the network make reactive power of key importance in system operations and planning. Moreover, the

many sources of uncertainty require reserves for the reliable operation of the power system. Reactive re