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Volume 151
Issue 1
IEE Proceedings - Generation, Transmission and Distribution
Volume 151, Issue 1, January 2004
Volumes & issues:
Volume 151, Issue 1
January 2004
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- Author(s): M.H. Haque
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 1 –7
- DOI: 10.1049/ip-gtd:20040057
- Type: Article
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P–V or Q–V curves are very commonly used to determine the maximum permissible load or static voltage stability limit of a power system. Voltage versus current curve or V–I characteristic is presented as a tool to assess the voltage stability limit. It requires only bus voltage and current data at present and some immediate past operating points. The above data are processed through the least squares method to establish the V–I characteristic. The extrapolated part of the characteristic is then used to estimate the critical load at the verge of voltage collapse. The proposed method does not require the knowledge of other system parameters or system-wide information. Any change in system condition usually modifies the V–I characteristic and thus the effect of the change is indirectly incorporated in finding the critical load through the V–I characteristic. The effectiveness of the proposed method is vigorously tested on the IEEE 30-bus system. Some of the results obtained by the proposed method are also compared with the corresponding actual values found through repetitive power flow simulations and are observed to be in excellent agreement. - Author(s): Y. Sun ; Y. Xinlin ; H.F. Wang
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 8 –18
- DOI: 10.1049/ip-gtd:20040059
- Type: Article
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Optimal power flow with transient stability (OTS) is a nonlinear optimisation problem in functional space that can be transformed to a static optimisation problem via constraint transcription techniques. However, the solution of the transformed OTS by ordinary numerical methods involves a massive calculation due to the stability constraints. Hence, the authors propose a penalty-based approach for OTS, in which the adjoint equation method is applied to evaluate the gradient of the penalty term associated with the stability constraints. It is demonstrated that the implementation of the adjoint equation method significantly reduces the computational burden in solving the OTS. A numerical test on a power system using prototype code is presented. - Author(s): L.A.Ll. Zarate and C.A. Castro
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 19 –26
- DOI: 10.1049/ip-gtd:20040058
- Type: Article
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The paper presents a simple, fast and reliable method for determining the distance in parameter (load) space from the system current operating point to the critical point for which voltage instability and even voltage collapse may occur. Sensitivity analysis is used to drive the system from the base case operating point to the vicinity of the critical point along a predefined load increase direction. In case the sensitivity analysis drives the system to the infeasible operating region, a special load flow method with step size optimisation is used so that relevant information can be obtained to restore the feasibility. Finally, the critical point is estimated from a certain number of conventional load flow calculations for different operating points in the vicinity of the critical point, by increasing the load along the predefined direction. The security margin to voltage collapse is obtained at a low computational cost. Simulation results for small and large power systems are shown to validate the effectiveness of the proposed method. - Author(s): Y.C. Kang ; S.H. Ok ; S.H. Kang ; P.A. Crossley
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 27 –35
- DOI: 10.1049/ip-gtd:20030982
- Type: Article
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When the magnetic circuit of a conventional protection current transformer (CT) enters saturation, the wave-shape of the secondary current distorts due to the increase in the excitation current. The distortion can be detected by analysing the secondary current using an algorithm that evaluates the first, second and third difference functions. The first difference contains points of inflection, which correspond to the start and end of each saturation period. The second and third differences convert the discontinuities at the points of inflection into pulses that can be used to detect saturation. The design and evaluation of an algorithm for detecting CT saturation using the third difference function is described. A low-pass filter, required for anti-aliasing and noise rejection, softens the discontinuities and reduces the magnitude of the pulses seen in the second and third difference signals. The softening effect is pronounced when the cut-off frequency of the filter is reduced. The sampling rate of 64 samples/cycle is used and the currents are passed through a first-order low-pass RC anti-aliasing filter with a cut-off frequency of from 1920 to 480 Hz. Experimental test results clearly demonstrate that the algorithm successfully detects the start and end of each saturation period. Results are obtained when a prototype detector based on a digital signal processor was used on a high current test-rig. Results indicate that the detector can correctly detect when the secondary current signal is distorted and in all the test cases the detector operated correctly. - Author(s): E. Calixte ; Y. Yokomizu ; H. Shimizu ; T. Matsumura ; H. Fujita
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 36 –42
- DOI: 10.1049/ip-gtd:20040060
- Type: Article
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Calculation was made to examine the reduction of the rating required for circuit breakers by using series-connected resistive and inductive fault current limiters (FCLs) under various fault locations. In the model of the inductive FCL, a capacitance Cp consisting of a coil stray capacitance and a necessary additional capacitance was taken into account. The insertion of the resistive FCL and the inductive FCL with Cp=100 nF into the power system proved to decrease the severity of the interrupting duty so that a lower-rated circuit breaker can be used. However, the introduction of the inductive FCL with Cp=10 nF was found to lessen the fault current, while raising the rate of rise of the recovery voltage. From the variation of the breaking condition, the limiting impedance required to allow a circuit breaker to perform a satisfactory interruption is discussed. - Author(s): B.C. Pal ; B. Chaudhuri ; A.C. Zolotas ; I.M. Jaimoukha
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 43 –50
- DOI: 10.1049/ip-gtd:20030998
- Type: Article
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A robust damping control design methodology for a thyristor controlled phase angle regulator using global signals is proposed based on the simultaneous stabilisation approach. The numerical design algorithm determines the controller parameters in order to guarantee closed-loop poles in the left half plane with preferential treatment to those corresponding to the inter-area modes. Plant models under different operating conditions are incorporated in the design formulation to achieve the desired performance robustness. A three-input/single-output controller is designed for the TCPAR to provide adequate damping to the critical inter-area modes of a study system model. Based on the observability of the inter-area modes, real power flows from remote locations are used as feedback stabilising signals. The damping performance of the controller is examined in the frequency and time domains and is found to be robust against varying power-flow patterns, nature of loads, tie-line strengths and system non-linearities, including saturation. - Author(s): B. Singh ; S.S. Murthy ; S. Gupta
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 51 –60
- DOI: 10.1049/ip-gtd:20040056
- Type: Article
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The modelling of an electronic load controller (ELC) for a self-excited induction generator (SEIG), used for power balancing at varying consumer load as required for stand alone micro-hydel generators driven by uncontrolled turbines, is presented. The implemented ELC consists of a rectifier-chopper system feeding a resistive dump load whose power consumption is varied through the duty cycle of the chopper. While the dynamic modelling of the SEIG is carried out using d-q variables in a stationary reference frame including magnetic saturation, the ELC is modelled through circuit concepts incorporating a switching function. Both the modelling and control technique of the ELC-SEIG are validated through simulated and experimental results. - Author(s): T.J. Gallagher and I.M. Dudurych
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 61 –66
- DOI: 10.1049/ip-gtd:20030927
- Type: Article
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A mathematical model of the phenomenon of corona on an HV transmission line under the influence of overvoltage surges is presented. This model has been incorporated into the alternative-transient-program/electromagnetic-transients-program (ATP-EMTP) as a user-defined component, using the MODELS feature of this program. This component has been inserted as a nonlinear voltage-dependent capacitance at regular intervals along the transmission line, in order to compute the attenuation and distortion of the lightning-induced surges as they propagate along the line. The proposed model is verified thoroughly by an extensive comparison of the simulation results from the paper with direct measurements by previous authors in the course of a number of physical tests, as well as with results of simulations by other authors. It is shown in the paper that the omission of the corona phenomenon can lead to noticeable errors in the assessment of both the steepness and peak value of the surge waveform as it propagates along the line. These facts are especially relevant to the problem of insulation co-ordination on overhead lines. The model used in the paper is applied to a study of the lightning performance of 110 kV overhead lines. - Author(s): W. Mingli and F. Yu
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 67 –72
- DOI: 10.1049/ip-gtd:20030981
- Type: Article
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67
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When calculating the internal impedance of solid or tubular cylindrical conductors, Bessel functions are involved if the skin effect has to be taken into account. Under unfavourable conditions, large parameters of the Bessel functions will occur, which will lead to unreliable results if the Bessel series are computed directly. Using the polynomial approximations of Bessel functions, closed-form formulas are developed to deal with this problem. For the convenience of applications, several sets of curves, for both the skin effect resistance ratio and internal inductance ratio of solid and tubular cylindrical conductors, which cover different ranges of parameters, are presented. - Author(s): C.C. Wu and N. Chen
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 73 –77
- DOI: 10.1049/ip-gtd:20040028
- Type: Article
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A methodology is proposed, for the fast-response reserve (FRR) dispatch in an isolated power system with frequency-based reserve constraints (FBRC), and implemented on the Taiwan power system. The fast-response reserve has two functions: regulating frequency and offering an emergency reserve. The FRR is provided by several sources, primarily, generator, load shedding and natural fall in demand due to falling system frequency. The paper deals only with FRR from generator response, which includes pumped storage. The load-frequency sensitivity factor (LFSF) is used to evaluate network behaviour following a contingency. The paper suggests that the one-minute recovery frequency following a contingency would be a more appropriate measure of system security and would represent an enhanced reserve policy. Three actual examples are used to study the influence of FRR on system security and to examine the merits of the methodology. - Author(s): J. Su and C. Chen
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 78 –82
- DOI: 10.1049/ip-gtd:20030739
- Type: Article
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78
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An accurate linearisation technique for multi-input power systems with nonlinear loads is presented. The nonlinear differential algebraic system (NDAS) considered is not in the state equation form. The definitions of M derivative and M bracket are similar to the definitions in classic differential geometric theory and some related revised results are introduced. M derivative and M bracket are used to obtain the feedback control law for the NDAS. The approach is used to design a nonlinear static VAr compensator (SVC) controller for a single-machine infinite system with nonlinear loads. The simulation results show that the nonlinear SVC controller improves damping and the voltage level to a greater extent than conventional controllers. The control law is even effective when the nonlinear loads are varied. - Author(s): Z. Yan ; Y. Liu ; F. Wu ; Y. Ni
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 83 –89
- DOI: 10.1049/ip-gtd:20030940
- Type: Article
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For a given one-parameter nonlinear system, the simplest bifurcation is the quadratic turning bifurcation where the Jacobian matrix becomes singular due to rank deficiency 1. To overcome the difficulty in solving the quadratic turning point caused by the singularity of the Jacobian matrix, the conventional Newton method can be applied to the so-called Moore-Spence determination system to solve for the quadratic turning point. However, the Moore-Spence system has much higher dimensions and causes much more complexity in factorisation of the extended Jacobian matrix. In the paper, by introducing an auxiliary variable and an auxiliary linear equation into Newton iterations in solving the Moore-Spence determination system, a matrix reduction technique can be worked out to solve the Moore-Spence extended equations much more efficiently. The high dimensions of the matrix can thus be reduced and the complexity involved in matrix factorisation can be reduced noticeably. The technique is proposed for general nonlinear systems. Formulation is derived for applying this technique to solving quadratic turning points, or say nose points, on load-flow solution curves of power systems. Computer tests on the IEEE 30-busbar system and a 2416-busbar East China power system are reported to show the effectiveness of the suggested technique. - Author(s): A.D. Polykrati ; M.P. Paisios ; C.G. Karagiannopoulos ; P.D. Bourkas
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 90 –94
- DOI: 10.1049/ip-gtd:20030941
- Type: Article
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p.
90
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In installations of lightning protection systems various types of electric couplings are used. Such couplings must have the ability to conduct heavy lightning currents. In the paper, a mathematical model and approximate equations are proposed, concerning the temperature rise estimation at these components, during lightning discharges. The results of experiments carried out to validate the mathematical model, satisfactorily comply with the theoretical models and it can be reliably concluded that the final temperature rise primarily depends on the initial crossing resistance, the coupling's mass and the peak-current-pulse value. The proposed model could be useful in the design of these couplings so that they meet satisfactorily and adequately the requirements of reliability established by the international standards. - Author(s): K.L. Butler-Purry ; N.D.R. Sarma ; I.V. Hicks
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 95 –102
- DOI: 10.1049/ip-gtd:20040029
- Type: Article
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Service restoration is an important problem in naval shipboard power systems. When faults occur as a result of battle damage or equipment failure and are isolated by protective devices, some critical loads are left without supply. Fast restoration of supply to these vital loads is necessary for system survivability. Loads have different priorities that must be considered during restoration in the shipboard power systems (SPS). These loads are categorised as vital or non-vital. Vital loads have two paths through which they can be supplied. Under some circumstances, it may be preferred to supply a vital load through one of the two paths. Butler et al have developed a method to restore maximum loads in SPS based on the fixed-charge network flow method. An enhancement to their method is proposed to handle priority for loads and paths while restoring service in SPS. The proposed method is illustrated with some case studies on a simplified SPS. - Author(s): R.A. Jabr and B.C. Pal
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 103 –108
- DOI: 10.1049/ip-gtd:20040030
- Type: Article
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An implementation of the weighted least absolute value (WLAV) method for obtaining an estimate of the state of the power system is presented. Most of the known WLAV methods use some form of linear programming software to find the best estimate. The paper shows that it is possible to obtain a WLAV estimate by simply applying the Newton-Raphson method to the set of equations that yield the critical points. The resulting iterative scheme corresponds to solving a sequence of linear weighted least-squares (WLS) problems. The proposed implementation enables the use of well-known techniques of WLS estimation and, consequently, facilitates the integration of the WLAV function in an energy management system. Test results on standard IEEE test systems reveal that the proposed implementation is competitive with a standard WLAV algorithm that uses a state-of-the-art implementation of an interior-point method. - Author(s): K.L. Lo and L. Khan
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 109 –118
- DOI: 10.1049/ip-gtd:20030942
- Type: Article
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A hierarchical-micro-genetic-algorithm-(H-μGA)-based strategy is presented for suitable weight selection in ℋ∞ loop-shaping robust damping control of flexible AC transmission system (FACTS) devices via normalised coprime factorisation. In ℋ∞ robust control design, the selection of a weighting function is an arduous and time consuming task. To muddle through this dilemma, an HGA in liaison with a micro-GA is employed to simultaneously select an appropriate structure and parameters of the weighting function in order to achieve a desired performance without the usual trial and error practice. To evaluate the effectiveness of the proposed technique, ℋ∞ robust damping control systems for SVC and TCSC are investigated and compared with the classical ℋ∞ loop-shaping control systems design. The performance and robustness of the proposed FACTS damping controls are validated through small signal and large signal simulations in a multi-machine power system. - Author(s): J. Barquín ; E. Centeno ; J. Reneses
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 119 –126
- DOI: 10.1049/ip-gtd:20040055
- Type: Article
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The paper proposes a model to represent medium-term hydro-thermal operation of electrical power systems in deregulated frameworks. The model objective is to compute the oligopolistic market equilibrium point in which each utility maximises its profit, based on other firms' behaviour. This problem in not an optimisation one. The main contribution of the paper is to demonstrate that, nevertheless, under some reasonable assumptions, it can be formulated as an equivalent minimisation problem. A computer program has been coded by using the proposed approach. It is used to compute the market equilibrium of a real-size system. - Author(s): G.C. Stamtsis and I. Erlich
- Source: IEE Proceedings - Generation, Transmission and Distribution, Volume 151, Issue 1, p. 127 –131
- DOI: 10.1049/ip-gtd:20030946
- Type: Article
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In the liberalised environment of modern electricity markets one of the most important tasks of the independent system operator is to carry out a congestion management efficiently. An estimation of the contribution of market participants to the congestion component of nodal prices is presented. Furthermore, a study of the producers' and consumers' bid behaviours is also provided. This study is based on a nodal price analysis and the use of distribution factors. Simulation results are presented for the IEEE 14-bus system and also a realistic high voltage network.
Use of V–I characteristic as a tool to assess the static voltage stability limit of a power system
Approach for optimal power flow with transient stability constraints
Fast method for computing power system security margins to voltage collapse
Design and evaluation of an algorithm for detecting current transformer saturation
Reduction of rating required for circuit breakers by employing series-connected fault current limiters
Simultaneous stabilisation approach for power system damping control design through TCPAR employing global signals
Analysis and implementation of an electronic load controller for a self-excited induction generator
Model of corona for an EMTP study of surge propagation along HV transmission lines
Numerical calculations of internal impedance of solid and tubular cylindrical conductors under large parameters
Frequency-based method for fast-response reserve dispatch in isolated power systems
Static VAr compensator control for power systems with nonlinear loads
Method for direct calculation of quadratic turning points
Model for temperature estimation of electric couplings suffering heavy lightning currents
Service restoration in naval shipboard power systems
Iteratively reweighted least-squares implementation of the WLAV state-estimation method
Hierarchical micro-genetic algorithm paradigm for automatic optimal weight selection in ℋ∞ loop-shaping robust flexible AC transmission system damping control design
Medium-term generation programming in competitive environments: a new optimisation approach for market equilibrium computing
Congestion analysis and participants' behaviour in a pool market
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