By Topic

Universities Power Engineering Conference, 2004. UPEC 2004. 39th International

Date 6-8 Sept. 2004

Go

Filter Results

Displaying Results 1 - 25 of 90
  • 39th International Universities Power Engineering Conference 2004

    Page(s): 0_1
    Save to Project icon | PDF file iconPDF (110 KB)  
    Freely Available from IEEE
  • [Blank page]

    Page(s): 0_2
    Save to Project icon | PDF file iconPDF (11 KB)  
    Freely Available from IEEE
  • 39th International Universities Power Engineering Conference (IEEE Cat. No. 04EX858)

    Save to Project icon | Request Permissions | PDF file iconPDF (222 KB)  
    Freely Available from IEEE
  • Authors index

    Page(s): xxxiv - xl
    Save to Project icon | PDF file iconPDF (572 KB)  
    Freely Available from IEEE
  • Development of harmonic measuring system using PIC

    Page(s): 929 - 933 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (659 KB)  

    A harmonic measurement has been carried out in a building of a university campus. The measurement and an EMTP simulation make clear that the 7th harmonic is the maximum and it is caused by a resonance between compensation capacitors of ballasts for mercury lamps and an inductance of the distribution line. Time-dependency of the harmonic is also observed. A simple and cost-effective harmonic measuring system using a peripheral interface controller (PICmicro/spl reg/ microcontroller) has been developed for an investigation of the harmonic characteristic. This measuring system has an A/D converter and a radio for synchronizing a clock which is indispensable for a multi-point measurement. To achieve a high accuracy, a fundamental component of the system voltage is removed by a phase locked loop oscillator and a differential amplifier. Another accuracy improving method using a capacitor connected to an outlet is proposed. Because the harmonic current flowing into the capacitor increases in proportion to the order of the harmonics, high-order harmonics can be measured accurately. An estimation method of a line inductance, which is a cause of the resonance, is also proposed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Voltage dip ride-through control of direct-drive wind turbines

    Page(s): 934 - 938 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (692 KB)  

    With an increasing amount of wind energy installed, the behaviour of wind turbines during grid disturbances becomes more important. Grid operators require that wind turbines stay connected to the grid during voltage dips. This contribution presents a controller that can be used to keep direct-drive wind turbines with permanent magnet generator connected to the grid during voltage disturbances. The behaviour of the wind turbine during a grid faults is demonstrated by simulations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Real-time assessment of differential relay protection on marine more-electric systems

    Page(s): 939 - 943 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (829 KB)  

    The development of more-electric environments in marine systems has been growing significantly in recent years. A primary driver for this growth has been the technological feasibility and recognised benefits that integrated full electric propulsion (IFEP) systems offer over more traditional mechanical propulsion systems. Simulation models are essential in supporting the development of IFEP systems from concept through to in-service product, by facilitating regular system evaluation and thereby ensuring that the in-service product has operational characteristics very similar to those originally specified. In addition, hardware-in-the-loop real-time simulation offers added value in further mitigating development risks. This paper will examine the real-time interaction of hardware differential protection relays and a simulated marine power network. The model development and testing process will be presented and include results demonstrating the operation of the power system and the associated protection system under a variety of conditions. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Study of the direction of the harmonic injections in the electrical power systems

    Page(s): 944 - 947 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (556 KB)  

    A simple measurement of a harmonic current in an unspecified point of the network cannot detect the transit direction of this current. The characterization of the harmonic currents flow direction harmonic currents requires a solid criterion, which will easily identify the real direction of these currents, consider their effects and then attenuate them. The criterion which seems to satisfy these requirements is that of the harmonic active P/sub h/ or reactive Q/sub h/ powers. In this paper the criterion of the harmonic active power P/sub h/ is developed. It arises from the results obtained that the harmonic active power consumed by a non pollutant consumer is positive (P/sub h/>0), whereas it is negative for a polluter one (P/sub h/<0). The criterion is also investigated using case studies and mathematical analysis. To validate the computation results, simulations were carried out under Matlab/Simulink. The results obtained during simulation show that P/sub h/ is positive whatever the harmonic currents intensity in the network is for a clean consumer whereas it is negative for pollutant consumer. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Voltage sag analysis on three phase systems using wavelet transform and probabilistic neural network

    Page(s): 948 - 952 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (706 KB)  

    The ever growing diffusion of susceptible loads in power system result in increasing susceptibility to power quality problems. For this reason power quality data are recorded by utilities with the aim of identifying the origins of these disturbances in order to improve the reliability of the electrical system and thus to reduce their impact on customers. In this paper a classification algorithm for automatic analysis of recorded power quality event data is presented. The approach is based on wavelet analysis and a probabilistic neural network classificator. The discrete wavelet transform (DWT) is used to detect fast changes in the voltage signals. It is possible to detect carefully the starting and the recovery times of the disturbance and other features, such as the start slew rate and intermediate rate voltage and the number of phases involved for each fault event. These features are the input patterns of the second step of the classification algorithm based on a probabilistic neural network (PNN) in order to classify voltage sag events into four classes (network faults, motor starting, motor re-acceleration after fault, transformer energising). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Method of critical distances for stochastic assessment of voltage sags in a meshed distribution system

    Page(s): 953 - 956 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    This paper is concerned with the method of critical distances for stochastic assessment of voltage sags in a large complicated distribution system. As the system is meshed, the method of critical distances is extended. Critical percentage of the feeders is developed from the critical distance in convenience to use the data provided by the industrial customer. The three phase short circuit faults in different locations, i.e. in the distribution system and in the public transmission system, are investigated detailed. The critical percentage of the feeders for each PCC is calculated. The results show that short circuit faults in the distribution system at 110 kV level will cause serious voltage sags, the spurious equipment trips are mainly due to the faults in the onsite system, not in the public utility system. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Influence and analysis of voltage sags on electric power systems for industrial plants

    Page(s): 957 - 960 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (597 KB)  

    Electric power system of general industrial plants usually has many induction motors as loads. The influence of voltage sags can cause big disturbances on the system, depending upon the kind and composition of the loads, like having large induction motors which display constant power characteristics for fluctuation of voltage. Analysis and simulation software for electric power system analysis is essential to quantitatively evaluate this phenomenon. This paper presents the results of analysis of the influence of voltage sags that is carried out in an electrical power system model. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The impact of small embedded generation within the UK electricity market

    Page(s): 961 - 965 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (823 KB)  

    Worldwide, the electricity industry is undergoing a period of sustained change. Pressures introduced by market reform and environmental imperatives have moved investment from large fossil fuel and nuclear plants to smaller distributed embedded systems. The UK market has reflected these changes by the introduction of the New Electricity Trading Arrangements (NETA) and by the publication of the Government's recent energy policy that places heavy emphasis on renewable energy sources. The scale of renewable energy plant is smaller than that of traditional generation technologies. Its inherent flexibility offers commercial benefits for load matching within the balancing and settlement code by reconciliation of actual and predicted demand or generation positions. From the perspective of the generators and system (SO) and distribution network operators (DNO) new problems are introduced. Variable power flows can lead to increased system losses and voltage management issues. This paper outlines the economic and technical issues involved in the trading, generation, and distribution of electricity produced by such generators. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An overview of voltage sag theory, effects and equipment compatibility

    Page(s): 966 - 972 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (903 KB)  

    In the modern industrial world, many electronic and electrical control devices are part of automated processes, to increase energy efficiency and productivity. Due to the fact that most of these devices are designed with the use of modern power electronics, they are characterized by an extreme sensitivity on power quality variations. This paper describes an overview of the theory and effects of voltage sag. Reference to non-rectangular events, and the procedure to evaluate the power systems performance regarding voltage sag, through using particular indices to assess equipment compatibility issues is presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • New system harmonic indices for power quality assessment of distribution networks

    Page(s): 973 - 977 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (622 KB)  

    This paper deals with the harmonic indices and gives considerations about their random behavior; the indices taken into account refer to the entire electrical distribution system. System indices are useful metrics to qualify distribution systems (or a part of it) and are able to take into account different quality service aspects. Indices not yet introduced in the standards and recommendations are proposed; in particular system indices referred to peak factor of the distorted waveforms are proposed due to its ability to represent several detrimental effects on power system components. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Influences of dispersed generation on the performance of the electricity grid

    Page(s): 978 - 982 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (871 KB)  

    Dispersed generation (DG) is playing an increasing role in the electric power system. In order to investigate the influences of DG-units on the performance of the electricity grid, performance-indicators and their classification are useful to be defined. These classifications enable an objective evaluation of the current situation in the grid and the influences of dispersed generation. This paper gives a survey of the most important performance-indicators, presents classifications for reliability and voltage sags and gives an overview of the influence of dispersed generation on these two aspects. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Quality of the power network as affected by the penetration of distribution generation

    Page(s): 983 - 986 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (519 KB)  

    This paper presents a study for the effect of the presence of distribution generation DG on the distribution network. The system losses are calculated for different system configurations (with and without DG's). In addition, the study concerned with transient performance. So, the study system integrated by DG units is exposed to the most common disturbances i.e. load switching and the severest one: three-phase to ground faults. Results of this work should be valuable in planning studies. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Temporary islanded operation of dispersed generation on distribution networks

    Page(s): 987 - 991 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (758 KB)  

    The use of decentralized electrical energy resources may be a useful support to the main power supply. In particular, in the event of an upstream supply outage, the temporary islanding operation of dispersed generators in distribution networks might greatly improve the quality and continuity of the power supply. The aim of this work is to verify the feasibility of temporary grid-disconnected operation of autonomous portions of distribution networks that use embedded generators. The analysis focuses on the critical transients occurring at disconnection from and reclosure with the main supply. A realistic distribution network model with both rotating and static embedded generators has been considered. Suitable P-and V-f control schemes for static generators have been developed, making it possible to operate in both grid-connected and island modes. The simulation results show that the presence of static (or inverter interfaced) generators with suitable control schemes may greatly improve the steady-state as well as transient performance of the islanded generation park. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Line switching reconfiguration corrective action for overloads in power systems

    Page(s): 992 - 998 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1032 KB)  

    This paper proposes an on line technique to select the most effective lines to be switched out of service to reduce overloads in other lines in power systems. A partial rescheduling of spinning reserve generation is then carried out to a further reducing of line overloads using a proposed formula. A contingency analysis of switchable lines is introduced based on the sensitivity parameters of the N-matrix. Two proposed indicators are presented of line overloading following a line outage: the first indicator is derived from the N-matrix after a line outage, while the second indicator is derived from the N-matrix before and after line switching. The second indicator provides an estimate of line power flows after one or more lines have been switched out of service. A proposed recursive of the N-matrix is used to reflect the line switched out. The overall technique provides a simple new tool, with a substantial saving in computer time, which could be used in a control center to aid the operators whenever a power system is in distress due to overload. Results are presented for three standard test power systems to which the new algorithm has been applied. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Using performance indices and analytic hierarchy process to select best dispatch option of energy markets

    Page(s): 999 - 1003 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (794 KB)  

    This paper presents some dispatch options and performance indices to compare these options. For each dispatch alternative, we propose to use measures for transmission congestion, energy prices, total system utilization, total system losses, and steady-state voltage stability margin. These measures are used to indicate level of system usage, congestion severity, and system security under different dispatch scenarios. The measures presented may enable the dispatch decision-making entity, such as the system operator, to compare and decide which dispatch among different dispatch scenarios is the optimal, based on agreed-upon preferences. For the decision-maker to make a compromise to decide which dispatch is better based on the established preferences or priorities, we suggest to use the analytic hierarchy process (AHP), which is a method that can handle human judgment numerically in complex decision-making processes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new method for detecting the point of voltage collapse

    Page(s): 1004 - 1008 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (709 KB)  

    This paper presents a new method for the detection of the point of collapse and a new index for the definition of the distance of the voltage collapse point. Performance index to detect and predict stability problems such as the voltage collapse have been a permanent concern for researchers and technical staff in power systems operation. This index can be used on-line or off-line to help operators determine how close the system is to a possible collapse and is a useful analysis tool for planning in power systems too. Numerical experiments using standard IEEE 14 and 57 bus systems show that the proposed method can compute the voltage collapse point using several different scenery of load increase or line outages. The methodology proposed may be easily implemented in any power flow program. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A decentralized approach for optimal electricity trade schedule using multi-agent systems

    Page(s): 1009 - 1013 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (705 KB)  

    Power industry has been undergoing deregulations to introduce competitions among market participants. With the fast development of interconnected power systems, the optimal wholesale electricity trade schedule is an important issue in interconnected power systems under transmission open access. In this paper a decentralized approach is proposed to solve the problem using multi-agent systems (MAS). In the new approach an agent is used to act as PX (power exchange) and several agents coordinates to work out electricity trade schedule, the minimum production cost of the whole system can be reached and the complexity of calculation in single PX can be reduced. The simulation results show that proposed approach is effective. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Generation adequacy assessment incorporating wind energy capacity

    Page(s): 1014 - 1018 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (879 KB)  

    The assessment of generation adequacy in power networks which include high levels of intermittent generation capacity presents particular problems to power system planners and operators. In particular, networks with high levels of wind energy penetration require careful consideration. This paper deals with the generation adequacy assessment of the electrical network in the Republic of Ireland. In recent years, a significant level of wind generation has been added to, or is being planned for connection to the transmission and distribution networks in Ireland. The current installed wind capacity of 166 MW is forecast to increase to 775 MW within the next few years. This paper looks at the application of both the loss of load expectation (LOLE) and Monte Carlo techniques to the generation adequacy assessment in the Irish system. The LOLE is calculated for a range of levels of wind generation capacity. The efficacy of the method of representing the wind generation as a negative load (load-modifier method) is considered. The greater flexibility in analysis of adequacy using a Monte Carlo approach is also demonstrated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reliability level evaluation on the customer side for bilateral contract market

    Page(s): 1019 - 1023 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (667 KB)  

    This paper presents a reliability level evaluation scheme for customers to assess their outage risk. A bilateral contract model is proposed to express power suppliers as generators with forced outage rates. Outage related cost consisting of potential outage risks and estimated outage cost with weighting coefficients is also proposed as an index of the reliability on the customer side. By using this index, customers reliability level can be evaluate as the cost concerning to outage. Appropriate reliability level reflecting the characteristic of customers is obtained through setting procedure of weighting coefficients of the proposed outage related cost. Several numerical examples demonstrate the effectiveness of the proposed approach. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fundamental research challenges for active management of distribution networks with high levels of renewable generation

    Page(s): 1024 - 1028 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (871 KB)  

    This paper is concerned with critically evaluating existing and emerging active management concepts and defining the contributions that ongoing and future research activities can bring in supporting the implementation of active management in distribution networks. These aims are achieved by defining and then extrapolating from current understanding of active network management. The key contributions from completed and ongoing projects in the field are clearly presented. In addition, the gap is assessed between what is achievable with existing and emerging active management solutions and what is required from active management if renewable energy targets are to be met within the current grid capability. Several specific recommendations are made in the paper that have relevance to power utilities, generators, plant manufacturers, network planners and monitoring and control equipment providers. These recommendations will facilitate concept validation and the implementation of future active management schemes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A study on the reclosing in power system using energy function

    Page(s): 1029 - 1033 vol. 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (623 KB)  

    This paper proposes the high-speed reclosing operating method to improve for the stability in the power system. The proposed method calculates the reclosing time, taking the case of standard in which the reclosing is not done using the energy function of generator phase angle. And the execution of reclosing time is calculated, considering the acceleration/deceleration energy of the generator in during fault. It can be expected that the delta of generator is suppressed by this optimum reclosing operation. Therefore, the system stability can be expected to improvement by carrying out the high-speed reclosing, when the fault arose. At present, it has been set at the value which seems to be optimum considering various problems in the reclosing time. However, in those methods, the system stability improvement effect cannot be expected. It was demonstrated that the high-speed reclosing method have depression effect of the delta in the computer simulation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.