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Generation, Transmission and Distribution, IEE Proceedings-

Issue 2 • Date 16 March 2006

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Displaying Results 1 - 15 of 15
  • Distributed generation, reactive sources and network-configuration planning for power and energy-loss reduction

    Publication Year: 2006 , Page(s): 127 - 136
    Cited by:  Papers (20)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    Taking account of the mutual impacts of distributed generation, reactive power and network-configuration planning, a new and more comprehensive distributed-generation-planning problem including simultaneous distributed generation, reactive sources and network configuration planning is defined. By solving this problem the amount of distributed-generation resources (DGRs) and reactive-power sources (RPSs) in selected buses of a distribution system, are determined taking account of their outputs at different load levels, tap positions of voltage regulators (VRs) and the status of sectionalising switches, in order to minimise the cost of power, energy losses and the total required reactive power subjected to a given total of distributed generation. Since the defined planning problem is a combinatorial one, a solution algorithm based on tabu search, that is an efficient heuristic method to a combinatorial-optimisation problem, is proposed. Various memory structures including short-, intermediate- and long-term memories have been implemented in the algorithm. The method has been tested on 33-bus and 69-bus radial distribution systems to demonstrate the performance of the algorithm and to investigate impact of some parameters such as maximum limits on size of DGRs (RPSs), constant or controllable outputs of these sources and different control variables sets on results of system planning. In addition, a novel technique for determining the candidate buses to install active (reactive) sources based on clustering system buses in view of assigning DGRs (RPSs) is presented. View full abstract»

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  • Estimation of typical squirrel-cage induction motor parameters for dynamic performance simulation

    Publication Year: 2006 , Page(s): 137 - 146
    Cited by:  Papers (9)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (637 KB)  

    Whenever the transient behaviour of a squirrel-cage induction motor is studied, double-cage model parameters are necessary. These parameters are usually hard to obtain. An estimation of typical double-cage induction parameters with regression-based equations that depend on mechanical power and line voltage is proposed. The starting current and torque, maximum torque, full-load slip and efficiency, calculated with the estimated typical parameters, are compared with the data of 608 low-voltage induction motors obtained from different manufacturers. The features of different power induction motors are well approximated with the proposed equations. View full abstract»

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  • Impact of intentional islanding of distributed generation on electricity market prices

    Publication Year: 2006 , Page(s): 147 - 154
    Cited by:  Papers (9)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (204 KB)  

    The battle for electricity customers in an increasingly competitive and deregulated market environment is one of the challenges facing the electric power utilities of today. Customers expect a reliable and efficient supply of power from their utilities. One of the advantages that a distributed generator (DG) can provide to the electric utility and to customers is the possibility of improving the continuity of supply by implementing safe intentional islands in the event of upstream utility supply outage. Implementing intentional islanding of DG in a deregulated era will have an impact on electricity market prices. This problem is considered in this paper by solving the optimal power flow problem while accounting for islanded operation. View full abstract»

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  • Dynamic topology processing in a radial distribution system

    Publication Year: 2006 , Page(s): 155 - 163
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    A dynamic topology processor for a radial distribution system using object-oriented methodology is presented. The potential of object-oriented design patterns is also employed to obtain an extendible design. The decorator design pattern is used to separate the topology-based attributes from the attributes representing physical characteristics of the objects. Using decorator pattern, responsibilities can be dynamically attached to or removed from the objects. The state design pattern is used to model the switching states of the tie and sectionalising switches. The proposed topology-processor algorithm is a local updating technique, hence less time consuming. The proposed algorithm has been implemented in C++ and tested with a modified 69-bus system. It has been found that the average CPU time required to modify the links between the objects following a switching operation is only 0.4 ms. View full abstract»

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  • Contribution of DFIG-based wind farms to power system short-term frequency regulation

    Publication Year: 2006 , Page(s): 164 - 170
    Cited by:  Papers (23)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (249 KB)  

    A control strategy that provides a doubly-fed induction generator (DFIG)-based wind farm with the capability to provide short-term frequency regulation is investigated. The controller manipulates dynamically the position of the DFIG rotor flux vector to slow down the generator allowing for a temporary surge in the power output, which helps to reduce the frequency drop following the transient period after the loss of network generation. A generic network that combines synchronous and wind-farm generation has been modelled and used for control system design and dynamic assessment. Studies are conducted for the DFIG operating at different speed and power output conditions. Simulation results are described which illustrate the contributions to frequency support of DFIG-based wind farms controlled with the proposed strategy. Machine data and control parameters are provided. View full abstract»

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  • Distortion of partial-discharge images caused by high-voltage harmonics

    Publication Year: 2006 , Page(s): 171 - 180
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (760 KB)  

    Nowadays, one of the main methods in diagnostics of high-voltage insulating systems is registration of partial-discharge (PD) pulses and their visualisation in the form of phase-resolved images. The paper describes the influence of high-voltage harmonics on partial-discharge phase-resolved images, which is crucial for proper identification and classification of PD patterns. The evolution of these images, depending on the total-harmonic-distortion (THD) parameter being an assessment factor, calculated by means of fast Fourier transform (FFT), is shown. Numerical simulation which illustrates the harmonic influence on PD is reported. Different harmonic-distortion instances of test voltage have been analysed along with the corresponding PD phase distributions. The measurement results were obtained on thermosetting insulation of a stator bar with the controlled harmonic content of the test voltage. The basic principles of harmonic analysis, along with the measurement set-up, are presented. It is shown that THD may only be a rough and global assessment factor. For the practical analysis of PD images, as a tool for insulation diagnostics and monitoring, the test-voltage frequency spectrum will be required. View full abstract»

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  • A numerical~stochastic technique for underground cable system design

    Publication Year: 2006 , Page(s): 181 - 186
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (425 KB)  

    First Page of the Article
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  • Electricity price forecasting with confidence-interval estimation through an extended ARIMA approach

    Publication Year: 2006 , Page(s): 187 - 195
    Cited by:  Papers (15)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (225 KB)  

    Accurate electricity price forecasting is a crucial issue concerned by market participants either for developing bidding strategies or for making investment decisions. Due to the complicated factors affecting electricity prices, accurate price forecasting turns out to be very difficult. The autoregressive integrated moving average (ARIMA) approach has been extended to make hourly market clearing price (MCP) forecasting in electricity spot markets with error correction and confidence interval estimation. The ARIMA model used for forecasting price and the method to implement price forecasting are presented first. Then the ARIMA approach is extended to include error correction for improving accuracy of price forecasting. Moreover, the confidence interval of the forecasted prices is estimated assuming the residual errors are in gaussian or uniform distribution. Hourly MCP forecasting of the Californian Power Market is used as a computer example, and the comparison with conventional ARIMA approach is given. Computer test results show clearly that the suggested extended ARIMA approach for spot price forecasting is very effective with satisfactory accuracy. It can work under very worse market conditions with high price volatility. View full abstract»

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  • Load-frequency control by hybrid evolutionary fuzzy PI controller

    Publication Year: 2006 , Page(s): 196 - 204
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (301 KB)  

    Power-system load-frequency control by fuzzy-PI (FPI) controller is proposed. During control, a fuzzy system is used to decide adaptively the proper proportional and integral gains of a PI controller according the area-control error and its change. To ease the design effort and improve the performance of the controller, design of the FPI controller by hybridising a genetic algorithm and particle-swarm optimisation, called FPI-HGAPSO, is proposed. FPI-HGAPSO is based on the hybrid of the genetic algorithm and particle-swarm optimisation. In FPI-HGAPSO, elites in the population of GAs are enhanced by particle-swarm optimisation and these enhanced elites are selected as parents for crossover and mutation operations. Simulations of the proposed evolutionary FPI-control approach on a multiarea interconnected power system with different kinds of perturbations are performed. The performance of the proposed approach is verified from simulations and comparisons. View full abstract»

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  • Integration of algorithmic and heuristic techniques for transition-optimised voltage and reactive power control

    Publication Year: 2006 , Page(s): 205 - 210
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (166 KB)  

    An integrated algorithmic and heuristic technique for transition-optimised voltage and reactive power control is presented. The method seeks to provide a 'transition-optimised' voltage and reactive-power control method. Essentially it considers voltage and reactive power control as a time-based scheduling problem, with the intention of avoiding unnecessary changes in status and output of reactive control plant. The demand profile is classified adaptively using a heuristic iteration method through evaluating the standard deviation and the range of the sequence of load-demand points. Furthermore, an algorithmic transition-optimised model of the volt/VAr control is then presented based on demand-pattern classification. The solution algorithm and different control strategies are studied in the transition optimisation. Case studies illustrate that the integrated algorithmic and heuristic technique for transition-optimised voltage and reactive power control not only effectively reduces power losses, but also greatly simplifies control operations. View full abstract»

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  • Multiple regression models as identifiers of power system weak points

    Publication Year: 2006 , Page(s): 211 - 216
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (175 KB)  

    Multiple regression models designed to identify the weak points of a power system are presented. On the basis of the determined reliability indices (duration of loss of load DLOL, and demand-not-supplied DNS), and by taking into account the apparent power difference criterion SDC as a voltage collapse proximity index, one can define the mutual relationship between these indices and the states of the particular power system components. The regression coefficients of MRMs indicate participation of each power system component (generators, transmission lines, substations, etc.) with regard to DLOL, DNS and SDC. Such information helps take measures of increasing the power system reliability and security. Subject-related results obtained in the Bosnian utility are given. View full abstract»

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  • Fuzzy short-term electric load forecasting using Kalman filter

    Publication Year: 2006 , Page(s): 217 - 227
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (283 KB)  

    A linear time-varying fuzzy load model for solving the short-term electric load forecasting problem is presented. The model utilises a moving window of current values of weather data as well as the recent past history of load and weather data. The parameters of this model are assumed to be fuzzy numbers with a triangular membership function yielding a fuzzy load that has both central and spread values. Both the load and load error are predicted for the following 24 hours on an hourly basis. The forecasting method is based on state space and the Kalman filtering prediction approach in conjunction with fuzzy rule-based logic. The technique is used recursively to estimate the optimal load forecast fuzzy parameters for each hour of the day. The central values of the fuzzy parameters represent the crisp forecast values while the spread values represent the amount of variation of the forecast. The predicted load spread value provides an approximate envelope of the extremes the load possibly takes. The effectiveness of the approach is demonstrated on real load and weather data which show the load forecast with a mean absolute percent error of less than 0.7% and absolute percent error standard deviation of 0.9%. View full abstract»

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  • Comparison and improvement of evolutionary programming techniques for power system optimal reactive power flow

    Publication Year: 2006 , Page(s): 228 - 236
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (354 KB)  

    Some recently developed evolutionary programming (EP) techniques for the optimal reactive power flow (ORPF) problem are investigated. By comparing the performances of four control schemes of the strategy parameter (CSSPs), two principles for designing effective CSSPs are identified and are further used to develop two improved CSSPs. The effectiveness of the Levy distribution based technique of adaptive fast EP is also studied. The investigations are conducted with simulations on the ORPF problems of the IEEE 14-, 30- and 118-bus standard test systems. View full abstract»

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  • Optimum allocation of reactive power for voltage stability improvement in AC-DC power systems

    Publication Year: 2006 , Page(s): 237 - 246
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2198 KB)  

    The dependence of the system voltage stability on reactive power distribution forms the basis for reactive power optimisation. The technique attempts to utilise fully the reactive power sources in the system to improve the voltage stability and profile as well as meeting the reactive power requirements at the AC-DC terminals to facilitate the smooth operation of DC links. The method involves successive solution of steady-state power flows and optimisation of reactive power control variables using linear programming techniques. The proposed method has been applied to a few systems and the results obtained on a real-life equivalent 96-bus AC and a two-terminal DC system are presented for illustration. View full abstract»

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  • Synchronous generator model identification using adaptive pursuit method

    Publication Year: 2006 , Page(s): 247 - 252
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (361 KB)  

    The application of an adaptive pursuit method for identification of a synchronous generator is investigated. The method is suitable for the identification of nonlinear systems in a noisy environment, particularly if online real-time adaptive control is the prime concern of the identification. The proposed method is first applied to a seventh-order nonlinear model of a synchronous generator with saturation effect and then tested on a micromachine system. In the study field voltage is considered as the input and the active output power and terminal voltages are considered as outputs of the synchronous generator. Simulation and experimental results show good accuracy of the identified models. View full abstract»

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