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This chapter describes performance of the power system stabilizer (PSS) of a large thermal power plant as tuned by the manufacturer. The stabilizer was redesigned based on extended phase compensation of the exciter input-the electrical torque transfer function and root locus analysis; and its effect on local, interplant, and interarea electromechanical oscillations was thoroughly analyzed. Participation factors and mode shapes were effectively employed to identify local, interplant, and interarea modes, as well as their characteristics. The PSS designed with extended phase compensation improves the damping of local and interplant oscillation modes considerably, and has some positive damping... 

A new method is proposed to analyze stability of descriptor systems with multiple commensurate time-delays. In this method, purely imaginary roots of the system are calculated, asymptotic behavior of root path at these roots is studied, and unstable regions of the system in the space of delays are determined. Moreover, the number of roots in each unstable region is calculated. Also necessary and sufficient conditions for τ-stabilizability of these systems are presented. Examples are provided to illustrate the effectiveness and validity of the proposed method. © 2019 The Franklin Institute  

This paper presents a new controller for power system stabilizer (PSS) that, unlike the conventional linear controllers, consists of both a linear and a nonlinear part. The linear part is properly designed to improve the small-signal stability margin and the damping of the local electromechanical modes. The nonlinear part is then designed to improve transient stability margin of the system without violating the features offered by the linear controller. Both parts are designed based on a perspective which attributes the system oscillations to a Hopf bifurcation (HB) phenomenon. More specifically, the design of the nonlinear part is done through the definition of a nonlinear index that... 

This paper mainly focuses on some behaviours of the bounded input-bounded output (BIBO) stability boundary in the linear distributed-order system (LDOS). Finding an association between changes of weight functions of LDOS and variation of its BIBO stability boundary is the other aim of this paper. To achieve these goals, the tangential lines of the BIBO stability boundary for the extremely high and low frequencies are founded in the first step. Then, the additive identity and the multiplicative identity for the weight function maintaining the stability boundary intact are determined. In addition, it is proved that multiplying a set of multiplication factors in the form of polynomials to the... 

In this paper, performance of power system stabilizer (PSS) of a large thermal power plant, as tuned by the manufacturer, is investigated. Then, the stabilizer is redesigned based on extended phase compensation of the exciter input - electrical torque transfer function and root locus analysis; and its effect on local, interplant and inter-area electromechanical oscillations is thoroughly analyzed. As Bisotoun PSS has a special structure with two inputs, frequency and power, its performance is compared with power-speed PSS. The effect of PSS with existing and new tunings on transient stability is also studied. Simulation results are verified by experimental test records. Copyright © 2006 IFAC... 

In this paper, the convergence and stability conditions of extended DMC in the control of nonlinear SISO and MIMO systems are investigated. The formulations are based on the ordinary DMC in which, with successive linearization of the nonlinear model and new interpretation of disturbance, the nonlinear extension is deduced. In addition, new convergence and stability criteria are derived for SISO and MIMO systems. These criteria include convergence and stability in the case of longer control (M > 1) and prediction (P > 1) horizons, as well as the finite and infinite sampling time. Finally, the simulation results for a MIMO (3 × 3) model, based on a power unit nonlinear plant, are presented. ©... 

Design of a classical controller is based on output feedback and structure of the controller. From modern control point of view, the information of input signals, output signals and internal behavior of the system are presented in state space model. In this paper, modern control is used to increase small-disturbance stability of power systems. Although many of existing power plants prefer to use classical Power System Stabilizers (PSS), these controllers have their own problems. Digital implementation of modern controllers is considered as a good advantage of modern PSS. In this paper, a modern control based PSS is designed for Bistun power plant and its output results are compared to the... 

In this paper, a class of the direct methods for discretization of fractional order transfer functions is studied in the sense of stability preservation. The stability boundary curve is exactly determined for these discretization methods. Having this boundary helps us to recognize whether the original system and its discretized model are the same in the sense of stability. Finally, some illustrative examples are presented to evaluate achievements of the paper  

This paper deals with the stability problem in LTI fractional order systems having fractional orders between 1 and 1.5. Some sufficient algebraic conditions to guarantee the BIBO stability in such systems are obtained. The obtained conditions directly depend on the coefficients of the system equations, and consequently using them is easier than the use of conditions constructed based on solving the characteristic equation of the system. Some illustrations are presented to show the applicability of the obtained conditions. For example, it is shown that these conditions may be useful in stabilization of unstable fractional order systems or in taming fractional order chaotic systems  

Robust stability analysis of multiorder fractional linear time-invariant systems is studied in this paper. In the present study, first, conservative stability boundaries with respect to the eigenvalues of a dynamic matrix for this kind of systems are found by using Young and Jensen inequalities. Then, considering uncertainty on the dynamic matrix, fractional orders, and fractional derivative coefficients, some sufficient conditions are derived for the stability analysis of uncertain multiorder fractional systems. Numerical examples are presented to confirm the obtained analytical results. Copyright © 2017 John Wiley & Sons, Ltd  

BIBO stability of linear time-invariant (LTI) distributed order dynamic systems with non-negative weight functions is investigated in this paper by using Lagrange inversion theorem. New sufficient conditions of stability/instability are presented for these systems accordingly. These algebraically simple conditions are relatively tight and their conservatism is adjustable. © 2018 Chinese Automatic Control Society and John Wiley & Sons Australia, Ltd  

BIBO stability of linear time-invariant (LTI) distributed order dynamic systems with non-negative weight functions is investigated in this paper by using Lagrange inversion theorem. New sufficient conditions of stability/instability are presented for these systems accordingly. These algebraically simple conditions are relatively tight and their conservatism is adjustable. © 2018 Chinese Automatic Control Society and John Wiley & Sons Australia, Ltd  

In this paper, performance of power system stabilizer (PSS) of a large thermal power plant, as tuned by the manufacturer, is investigated. Then, the stabilizer is redesigned based on extended phase compensation of the exciter input - electrical torque transfer function and root locus analysis; and its effect on local, interplant and inter-area electromechanical oscillations is thoroughly analyzed. As Bisotoun PSS has a special structure with two inputs, frequency and power, its performance is compared with power-speed PSS. The effect of PSS with existing and new tunings on transient stability is also studied. Simulation results are verified by experimental test records. © 2007 JD  

This paper studies fractional-order systems of retarded type with two independent delays, and determines the stability regions in spaces of delays. In this approach, an auxiliary polynomial is employed to calculate all purely imaginary roots of the characteristic equation of the system on the imaginary axis. Since roots of the characteristic equation are continuous with respect to delays, these purely imaginary roots determine the stability regions in delay space. Also, the necessary and sufficient condition for stability independent of delays is developed for the systems. Furthermore, a simple inequality constraint is established to obtain pure imaginary poles of the scalar systems.... 

The exact stability condition for certain class of fractional-order (multivalued) transfer functions is presented. Unlike the conventional case that the stability is directly studied by investigating the poles of the transfer function, in the systems under consideration, the branch points must also come into account as another kind of singularities. It is shown that a multivalued transfer function can behave unstably because of the numerator term while it has no unstable poles. So, in this case, not only the characteristic equation but the numerator term is of significant importance. In this manner, a family of unstable fractional-order transfer functions is introduced which exhibit... 

Various attempts have been made to derive linearized, reduced order models of induction generators. Due to the fact that there is usually numerous number of these machines in wind power plants, these models provide great facilities in calculations, and therefore are used widely in power system transient stability studies. In this paper, some of these methods are discussed and compared and then a method known as "balanced realizations" is used to reduce the dynamic order of the machine. Computer simulation shows that the last method markedly improves the accuracy of the resulting reduced order model. The improvement is demonstrated by comparing the response characteristics predicted by each... 

Online power system stability assessment during restoration has not been strongly addressed yet. The introduction of wide area measurement systems (WAMS), however, made it possible to monitor the stability online. This study technically presents a detailed analysis of stability during restoration using WAMS. The power system build-up strategy is used as the restoration approach, based on which the early and the last stages of restoration are to divide the power system into islands and interconnect them, respectively. In fact, the practical use of WAMS at the early stages of restoration provides precise determination of generators loading steps. Moreover, unification of phase angle references... 

This paper presents a novel approach for small signal stability assessment of a multi-machine system using only synchronized Phasor Measurement Units (PMUs) data. The proposed method does not need any information about the generators, network configuration or line impedances. By installing one PMU on each generator bus and using classical model for generator, all of the network and generators parameters needed for small signal stability analysis are estimated using the ambient data registered in the PMUs. Least square error estimation is used to obtain a reduced admittance matrix for the network in real-time. The estimated model is then used to evaluate the multi machine system dynamics in... 

Due to deterioration of fossil fuel and policy directives on greenhouse gas mitigation, wind power generation has been widely developed in recent years. This has raised many issues in terms of power system operation, dynamics, stability and etc. This paper reviews the effect of different kinds of wind turbines on power system stability. Since there are no existing surveys in this area, it provides a comprehensive overview in transient and dynamic stability. The contribution of this survey is to provide a comparison to determine which kinds of wind turbines is better from the system stability point of view. Furthermore, the effects of wind power generation with energy storage systems are... 

This study investigates the dynamic participation of wind power plants (WPPs) in the automatic generation control (AGC) task. The pre-specified model of wind farm in the AGC studies has been used. It is shown that operating of WPPs at the command mode results in a significant improvement in the frequency behaviour of power system due to their faster response. However, the WPPs may change their operation mode from the command mode to the maximum power point mode according to the wind speed conditions and load variations. This reduces the improvement in the frequency response. In this condition, the shortage in the wind power should be compensated by the conventional units. Thus, the share of...