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Volume 147
Issue 1
IEE Proceedings - Generation, Transmission and Distribution
Volume 147, Issue 1, January 2000
Volumes & issues:
Volume 147, Issue 1
January 2000
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- Author(s): A. Semlyen and M. Shlash
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 147, Issue 1, p. 1 –6
- DOI: 10.1049/ip-gtd:20000024
- Type: Article
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The generalisation and refinement of a very efficient modular harmonic power flow (MHPF) methodology, initially available for simple components only, is presented. Its capabilities have been extended to three-phase systems that may include: nonlinear elements, such as generators; components with distributed and frequency-dependent parameters, as in the case of transmission lines; and switched components, exemplified by a thyristor controlled series capacitance (TCSC). The exact modelling of complex components is carried out individually in the time domain using Poincaré acceleration for the fast and accurate calculation of the steady state. An incremental harmonic domain admittance matrix for the whole system is then used in an iterative process to obtain a system-wide solution. Numerical results for a small system serve to illustrate some details of the MHPF. - Author(s): J. Mutale ; G. Strbac ; S. Curcic ; N. Jenkins
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 147, Issue 1, p. 7 –14
- DOI: 10.1049/ip-gtd:20000003
- Type: Article
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Deficiencies in present-day loss allocation practices are demonstrated using as an example the substitution method presently applied in England and Wales to evaluate the impact of EG on losses. Two new loss allocation schemes are proposed; one based on the allocation of marginal losses and the other on the allocation of total losses. Loss allocation factors computed from the proposed schemes are specific to location and time of use. This is especially important for EG whose impact on losses varies in time and space. A notable feature of the proposed loss allocation coefficients is that they can be positive or negative and therefore can recognise the presence of counter-flows such as those due to the presence of EG. Application of the proposed loss allocation schemes is illustrated on a real network based 265-node generic distribution system model incorporating EG. - Author(s): S. Mishra ; P.K. Dash ; G. Panda
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 147, Issue 1, p. 15 –22
- DOI: 10.1049/ip-gtd:20000022
- Type: Article
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The unified power flow controller is one of the most versatile flexible AC transmission system devices, which can be used to control the active and reactive power flows in a transmission line by injecting a variable voltage in series and reactive current in shunt. The application of Takagi-Sugeno type fuzzy logic controllers for UPFC voltage source inverter control in a multi-machine power system environment is proposed. This type of fuzzy controller provides a wide range of control gain variation by including both linear and non-linear terms in the consequent part of the fuzzy rule base. The TS fuzzy controllers are quite general in that they use arbitrary input fuzzy sets, any type of fuzzy logic, and the general defuzzifier. Several computer simulation tests on a multi-machine power system indicate the significant damping performance of this new TS fuzzy controller for the UPFC. - Author(s): H.C. Tay and M.F. Conlon
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 147, Issue 1, p. 23 –30
- DOI: 10.1049/ip-gtd:20000026
- Type: Article
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The development of an unbalanced switching scheme for the power conditioning system of a superconducting magnetic energy storage (SMES) device is described. The pulse-width modulation switching scheme for a current-source inverter, based on the unified switching algorithm, is presented. A device sequencing scheme and pulse merging arrangement is developed which minimises low-order harmonics. The balanced switching scheme is extended to an unbalanced scheme where the positive and negative sequence components of the output AC currents are controlled directly by their respective modulation indices and delay angles. The switching scheme is implemented on an experimental SMES device and its performance is assessed with respect to modulation linearity, harmonic generation, independent control of active and reactive power, and independent control of sequence currents. - Author(s): L. Morán ; I. Pastorini ; J. Dixon ; R. Wallace
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 147, Issue 1, p. 31 –36
- DOI: 10.1049/ip-gtd:20000027
- Type: Article
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An active power filter connected in series to the power distribution system is presented and analysed. The series active power filter is implemented with a three-phase PWM voltage-source inverter and operates with a resonant LC passive filter connected in parallel to the power lines. The proposed scheme is able to simultaneously compensate current harmonics, the fundamental negative and zero sequence voltage components generated by the voltage source unbalance, and also eliminates the zero sequence current harmonic components that circulate through the neutral conductor. The active power filter is discussed in terms of the principles of operation under steady-state and transient conditions. The design and implementation of the power and control circuits are reported. Key predicted results are verified experimentally on a 5 kVA prototype model. - Author(s): K.W. Wang ; C.Y. Chung ; C.T. Tse ; K.M. Tsang
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 147, Issue 1, p. 37 –43
- DOI: 10.1049/ip-gtd:20000025
- Type: Article
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An improved probabilistic method using moments and cumulants of random variables for power system dynamic stability studies is presented. The uncertainties considered are system multi-operating conditions derived from operating curves of load powers and generations. The generator state and nodal voltages are solved from a stochastic load flow calculation. By means of the first and second order eigenvalue sensitivity representation, moments and cumulants of eigenvalues are determined from the statistical characteristics of nodal voltages and nodal injections. Probabilistic densities and conditional probabilities of critical eigenvalues are calculated from the Gram–Charlier series. In this method, random variables can have an arbitrary distribution. Dependencies among random variables and the interaction between expectation and covariance are all considered. Examination on two test systems shows that the proposed method can relieve/improve the conflict between computing requirement and precision. - Author(s): E. Agneholm and J. Daalder
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 147, Issue 1, p. 44 –50
- DOI: 10.1049/ip-gtd:20000058
- Type: Article
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Field studies have been performed in residential areas to determine the load restoration process after a disturbance. Similar measurements were also performed for individual houses with different heating supplies. Load aggregation for the different houses during the same outdoor conditions have been made for various durations of the outages, and a load model is presented. The cold load pick-up from individual houses is compared with field measurements from substations and with load models. Load curtailment schemes are analysed based on the collected data. - Author(s): P. Wang and R. Billinton
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 147, Issue 1, p. 51 –56
- DOI: 10.1049/ip-gtd:20000002
- Type: Article
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In capacity deficiency conditions caused by unscheduled outages in a generation and transmission system, system operators have to shed load at selected feeders in the distribution system to maintain acceptable operating conditions. Different load-shedding schemes can result in quite different load point reliability performance. Conventionally, the objective is to shed the minimum load subject to system security constraints. An optimum load-shedding technique is presented that can be used to improve the reliability of a local distribution system. Customer concerns regarding interruption costs are considered in the load-shedding procedure. The objective is to minimise the total system interruption cost. Cost weight factors are used to determine the load-shedding priority among feeders, and an enumeration technique is used to divide the capacity deficiency between feeders. The unreliability cost indices of two representative distribution systems are evaluated to illustrate the technique. - Author(s): M. Kurtović and S. Vujević
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 147, Issue 1, p. 57 –61
- DOI: 10.1049/ip-gtd:20000031
- Type: Article
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An extensive analysis has been carried out of the influence on touch voltage and earthing grid resistance of placing an additional substance in the trench surrounding the conductor. Earthing grid resistances and touch voltages have been computed by two different methods: a simple approximative analytical method and a much more accurate boundary element method. It has been shown that the approximate analytical method gives sufficiently good results. The influence of the additional substance in the trench on touch voltages is especially significant for large earthing grids, while the influence on earthing grid resistance is smaller. - Author(s): M.S. Kandil ; S.M. El-Debeiky ; N.E. Hasanien
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 147, Issue 1, p. 62 –68
- DOI: 10.1049/ip-gtd:20000023
- Type: Article
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A rule-based expert system (ES) for determining the realistic location alternatives of a developed generation expansion plan and the initial transmission expansion scheme of a typical fast development power system is described. In the proposed ES, the key variables that affect generating unit location are first identified. So, a multitude of technical, economical, environmental and feasible siting constraints are established by system planning engineers for different areas over the planning horizon. A set of decision rules relating these key variables are then established and stored in the knowledge base. With the knowledge base at hand, a list of realistic location alternatives of the new generating units is defined. However, to determine the optimal and sub-optimal location from this list, the system operating cost and the capacity of the tielines among different areas, as well as its investment, should be taken into consideration. Therefore, the electrical network is simplified as a generalised network programming (GNP) formulation, to optimise the location for new generation and its initial transmission expansion scheme simultaneously for each alternative. The optimum and sub-optimum alternatives that will minimise the overall system cost function and satisfy the demand requirements under normal operation and the contingency condition are obtained. The outcome of the proposed method will provide the first step on which the subsequent steps of transmission planning are based. The proposed method would be appropriate for an electric utility in which there is a central planning organisation. A practical application is given to demonstrate the usefulness of the developed prototype system.
Principles of modular harmonic power flow methodology
Allocation of losses in distribution systems with embedded generation
TS-fuzzy controller for UPFC in a multimachine power system
Development of an unbalanced switching scheme for a current source inverter
Series active power filter compensates current harmonics and voltage unbalance simultaneously
Improved probabilistic method for power system dynamic stability studies
Cold load pick-up of residential load
Optimum load-shedding technique to reduce the total customer interruption cost in a distribution system
Earthing grid parameters with conductor surrounded by an additional substance
Rule-based system for determining unit locations of a developed generation expansion plan for transmission planning
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