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Journal ArticleDOI

Dynamic Stability of Long Transmission Systems with Static Compensators and Synchronous Machines

01 Jan 1979-IEEE Transactions on Power Apparatus and Systems (IEEE)-Vol. 1, Iss: 1, pp 124-134
TL;DR: In this article, the static compensator and the excitation system control parameters are chosen in a coordinated manner from the stability limit plots, the extension of stability limits with a Static Compensator are quantised, later a second compensator is included for improving the system performance.
Abstract: This paper deals with the dynamic stability of long distance a.c. transmission systems operating at above 1 surge impedance loading and compensated entirely by automatically controlled shunt inductance device referred to as Static Compensators. Generalised system equations in the form X = AX, with a careful choice of state variables are developed via the subsystem concept and the eigenvalue technique used to establish the stability limits. The static compensator and the excitation system control parameters are chosen in a coordinated manner from the stability limit plots, the extension of stability limits with a Static Compensator are quantised, later a second compensator is included for improving the system performance and interaction studies.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the capability of the static var controller to provide damping in radial long distance transmission lines is investigated. But, the work in this paper is limited to the case of a single SVC station with equally spaced SVC stations.
Abstract: The capability of static var compensators to use supplementary signals for damping improvement has been studied. Damping is shown to be a function of the transmission system loading and a function of the static var compensator The study offers insights as to how static var compensators should be coordinated with respect to the transmission system. The technology under study is based on thyristor controlled reactor with switched capacitors. This paper is concerned with the capability of the static var controller to provide damping in radial long distance transmission lines. It is well known that the lack of positive damping sets a limit to the power transferable across a transmission line By use of supplementary feedback signals, the static var compensator can be made to enhance the system damping. This paper seeks to answer the following questions: 1) For a given design of the supplementary signal feedback, are there any operating regions in which negative damping is encountered? 2) What is the effect of an individual static var compensator in providing damping for a transmission system with multiple compensation systems? 3) What is the analytical model of a static var compensator which uses the thyristor controlled reactor technology? 4) How should the elements of the static var compensator be designed in conjunction with the transmission system when the objective is to improve damping? These questions are answered in the context of a radical line with equally spaced SVC stations as modelled in Fig. 1.

10 citations

DOI
01 Nov 1983
TL;DR: In this article, the TCR is fed through the sequentially controlled transformer taps, and two alternative approaches of sequence control of transformer taps are described; the feasibility of the proposed method has been verified experimentally.
Abstract: Owing to discontinuous current in a thyristor-controlled reactor (TCR) of a static VAR compensator, harmonic currents are generated in the supply system. The paper presents a new method for reducing these harmonics. In the method used, the TCR is fed through the sequentially controlled transformer taps. Two alternative approaches of sequence control of transformer taps are described. The feasibility of the proposed method has been verified experimentally.

10 citations

Journal ArticleDOI
01 Nov 1993
TL;DR: In this paper, a single input multiple output (SIMO) static VAR controller is proposed to stabilize torsional oscillations using an eigenstructure assignment technique, which can be easily implemented by a multiple proportion integral (MPI) controller using medium pressure turbine speed, two low pressure turbine speeds and generator shaft speed as the feedback signals.
Abstract: Stabilising torsional oscillations using a single input multiple output (SIMO) static VAR controller is investigated. An eigenstructure assignment technique is applied to design it. The designed controller can be easily implemented by a multiple proportion integral (MPI) controller using medium pressure turbine speed, two low pressure turbine speeds, and generator shaft speed as the feedback signals. Eigenvalue analyses under a wide range of series capacitor compensations and loading conditions, time domain simulations under a pulsed torque disturbance, and fast Fourier transform (FFT) analyses for system behaviour are all performed to demonstrate the effectiveness of the proposed controller.

10 citations

Journal ArticleDOI
TL;DR: In this article, a new controller, namely the combined reactive power and frequency (CRPF) auxiliary controller, has been developed and incorporated in the static var control system located at the middle of the transmission line.

10 citations

Dissertation
01 Jan 2004
TL;DR: In this article, the contribution of power system components such as load and static var compensators (SVC) that affect the inter-area oscillation (IAO) between groups of synchronous machines is analyzed.
Abstract: With the growth of power system interconnections, the economic drivers encourage the electric companies to load the transmission lines near their limits, therefore it is critical to know those limits well. One important limiting issue is the damping of inter-area oscillation (IAO) between groups of synchronous machines. In this Ph.D. thesis, the contribution of power system components such as load and static var compensators (SVC) that affect the IAO of the power system, are analysed. The original contributions of this thesis are as follows: 1-Identification of eigenvalues and mode shapes of the IAO: In the first contribution of this thesis, the eigenvalues of the IAO are identified using a correlation based method. Then, the mode shape at each identified resonant frequency is determined to show how the synchronous generators swing against each other at the specific resonant frequencies. 2-Load modelling and load contribution to damping: The first part of this contribution lies in identification of the load model using cross-correlation and autocorrelation functions . The second aspect is the quantification of the load contribution to damping and sensitivity of system eigenvalues with respect to the load. 3- SVC contribution to damping: In this contribution the criteria for SVC controller redesign based on complete testing is developed. Then the effect of the SVC reactive power on the measured power is investigated. All of the contributions of this thesis are validated by simulation on test systems. In addition, there are some specific application of the developed methods to real data to find a.) the mode shape of the Australian electricity network, b.) the contribution of the Brisbane feeder load to damping and c.) the effect of the SVC reactive power of the Blackwall substations on the active power supplying Brisbane.

7 citations


Cites background from "Dynamic Stability of Long Transmiss..."

  • ...However, it was found that SVC could improve damping of low frequency oscillations [91-96]....

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References
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Journal ArticleDOI
John M. Uudrill1
TL;DR: In this paper, the authors describe the small signal performance of a multi-machine synchronous power system by a set of differential equations of the form [x] = [A] [x], allowing standard multivariable control theory to be used in dynamic stability studies.
Abstract: Describing the small signal performance of a multi- machine synchronous power system by a set of differential equations of the form [x] = [A] [x] allows standard multivariable control theory to be used in dynamic stability studies. The construction of the [A] matrix for a multimachine power system involves the application of Kron's rotational transformation to the transmission network admittance matrix, and a matrix analysis of the synchronous machines using internal flux linkages as state variables.

140 citations

Journal ArticleDOI
01 Feb 1966
TL;DR: In this paper, a set of general coefficients related to the well known Heffron and Phillips constants is derived by means of matrix algebra, which allows complex impedance terms to be included in the analysis.
Abstract: The design of synchronous-generator automatic regulating equipment by linearisation techniques is now firmly established. The paper presents an obvious extension of one method, where, by means of matrix algebra, a set of general coefficients related to the well known Heffron and Phillips constants is derived, which allows complex impedance terms to be included in the analysis. In keeping with modern practice, these constants are incorporated in equations which are formulated as sets of first-order differential equations. This form provides a basis for future applications of optimal control theory, and, in addition, may be scaled more easily in both time and amplitude for analogue-simulation studies. A detailed example of a multiloop a.v.r. connected to a 30MW machine is given for reference purposes. The matrix methods, used in conjunction with the matrix iterative techniques of load-flow analysis, extend naturally to multimachine systems, allowing the dynamic operating and stability problem to be investigated with respect to possible future multimachine co-ordinated control schemes.

71 citations

Journal ArticleDOI
TL;DR: In this paper, a digital computer method for obtaining eigenvalue sensitivities of interconnected power systems is presented, especially suited to the analysis of detailed modelled synchronous machine systems where shaft and stator-network dynamic effects are significant.
Abstract: A practical digital computer method for obtaining eigenvalue sensitivities of interconnected power systems is presented. The method is especially suited to the analysis of detailed modelled synchronous machine systems where shaft and stator-network dynamic effects are significant. A unified structure in the construction of the state space equations permits the inclusion of a wide variety of control equipment and varying degrees of modelling complexity. Sample results are given for typical cases illustrating the significance of eigenvalue sensitivities. Specifically results are presented for a 4 generator hydroelectric system and for a 2 generator system exibiting subsynchronous torsional resonance.

47 citations

Journal ArticleDOI
01 Jun 1966
TL;DR: In this article, a detailed study of the effect of a voltage regulator on the stability of an alternator connected through a reactance to an infinite bus is performed, and the stability is analyzed by means of Nyquist loci calculated for the transfer functions of alternator and regulator.
Abstract: The paper records a detailed study of the effect of a voltage regulator on the stability of an alternator connected through a reactance to an infinite bus. The stability is analysed by means of Nyquist loci calculated for the transfer functions of alternator and regulator. The accuracy and speed of response of the system are also considered. The first part of the paper considers a simple regulator with proportional feedback, and it is shown that such an ideal regulator can extend the region of steady-state stability to a point corresponding to the maximum of the transient power-angle curve. Practical regulators are classified according to the nature of their transfer functions. The analysis provides a means of predicting their behaviour and explains how they affect the stability, accuracy and response. The effect of delay elements, integrator elements and derivative elements in the regulator is considered particularly; e.g. a buck-boost exciter, which effectively introduces an integrator element, gives good accuracy but less satisfactory response, and has a limited effect on stability, and a derivative regulator which gives rapid response and a large extension of the stability region, but has limited accuracy. Experiments performed on a model machine with various simulated regulators agreed well with the computed results. The computations allowed fully for the system parameters, including alternator resistance and alternator damping.

35 citations