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Stabilization of wind farm (WF) is considered one of the major serious issues for developing power systems based on renewable energy sources. A comparison of dynamic performances for FACTS devices like STATCOM and SVC is presented in this paper. Such devices are employed to stabilize WF integrated with multi-machine power system (WFMPS). Fuzzy logic controller (FLC) has been employed for controlling FACTS devices to enhance WFMPS performance under different abnormal conditions. Three-phase to ground short circuit fault has been taken into consideration in different locations of system. MATLAB/Simulink is used to perform the modeling and simulation of WFMPS. The obtained results demonstrate the effect of both SVC- and STATCOM-based FLC on damping the system oscillations and improving the system dynamic performance in the post-fault duration. The comparison confirms superior dynamic performance and fast fault recovery of STATCOM-based FLC through different fault conditions compared with SVC-based FLC. [ABSTRACT FROM AUTHOR]

The present research focuses on transient stability of multi-machine power systems in a full consideration regarding the performances of the Takagi-Sugeno fuzzy-based sliding mode control approach in association with the conventional sliding mode and also the optimal control approaches to improve the last finding outcomes in this area. Hereinafter, concerning the robustness of the sliding mode control approach toward parametric uncertainties and environment perturbations, in fact, a couple of different sliding mode control approaches are designed for mutual comparison, after a number of state-of-the-art technique considerations. To increase the control performance, the Takagi-Sugeno fuzzy-based approach is devised to provide the appropriate coefficients. Finally, the three control approaches are all carried out in the six-machine power system under the same condition and the investigated results are correspondingly provided to be analyzed. The results indicate that the proposed fuzzy-based control approach is well behaved with respect to other related ones. [ABSTRACT FROM AUTHOR]

Linear quadratic stabilizers are well-known for their superior control capabilities when compared to the conventional lead-lag power system stabilizers. However, they have not seen much of practical importance as the state variables are generally not measurable; especially the generator rotor angle measurement is not available in most of the power plants. Full state feedback controllers require feedback of other machine states in a multi-machine power system and necessitate block diagonal structure constraints for decentralized implementation. This paper investigates the design of Linear Quadratic Power System Stabilizers using a recently proposed modified Heffron-Phillip's model. This model is derived by taking the secondary bus voltage of the step-up transformer as reference instead of the infinite bus. The state variables of this model can be obtained by local measurements. This model allows a coordinated linear quadratic control design in multi machine systems. The performance of the proposed controller has been evaluated on two widely used multi-machine power systems, 4 generator 10 bus and 10 generator 39 bus systems. It has been observed that the performance of the proposed controller is superior to that of the conventional Power System Stabilizers (PSS) over a wide range of operating and system conditions. [ABSTRACT FROM AUTHOR]

Modeling of unified power flow control (UPFC) into multi-machine power systems by Wang, published by IET, has been widely quoted by many researchers. However, the correctness of the derivation of its equations has not been strictly scrutinized. The model cannot properly represent power system networks in its current form and need to be corrected. In this paper, the model proposed by Wang is revisited and the equations re-derived obtaining different results. The corrected model was developed and tested on three-machine and New England power systems installed with a UPFC. The DC link capacitor voltage is controlled in UPFC by modulating the phase angle of the excitation transformer voltage. The effect of the controller in damping of the low-frequency oscillations is demonstrated by using the proposed correct model and the results are compared with model presented by Wang. [ABSTRACT FROM AUTHOR]

The role of Power System Stabilizer (PSS) in the power system is to provide necessary damping torque to the system in order to suppress the oscillations caused by a variety of disturbances that occur frequently and maintain the stability of the system. In this paper, a PSS design technique is proposed using Whale Optimization Algorithm (WOA) by considering eigenvalue objective function. Two bench mark multi machine test systems: three- generator nine- bus system, two- area four- generator inter connected system working on various operating conditions are considered as case studies and tested with the proposed technique. Extensive simulation results are obtained and effectiveness of proposed WOA-PSS are compared with well - known PSO and DE based stabilizers under several disturbances. [ABSTRACT FROM AUTHOR]

We interpret and explain a phenomenon in short-term swing dynamics of multi-machine power grids that we term the Coherent Swing Instability (CSI). This is an undesirable and emergent phenomenon of synchronous machines in a power grid, in which most of the machines in a sub-grid coherently lose synchronism with the rest of the grid after being subjected to a finite disturbance. We develop a minimal mathematical model of CSI for synchronous machines that are strongly coupled in a loop transmission network and weakly connected to the infinite bus. This model provides a dynamical origin of CSI: it is related to the escape from a potential well, or, more precisely, to exit across a separatrix in the dynamical system for the amplitude of the weak nonlinear mode that governs the collective motion of the machines. The linear oscillations between strongly coupled machines then act as perturbations on the nonlinear mode. Thus we reveal how the three different mode oscillations-local plant, inter-machine, and inter-area modes-interact to destabilize a power grid. Furthermore, we present a phenomenon of short-term swing dynamics in the New England (NE) 39-bus test system, which is a well-known benchmark model for power grid stability studies. Using a partial linearization of the nonlinear swing equations and the proper orthonormal decomposition, we show that CSI occurs in the NE test system, because it is a dynamical system with a nonlinear mode that is weak relative to the linear oscillatory modes. [ABSTRACT FROM AUTHOR]

The low-frequency electromechanical oscillations (LFEOs) in electric power system are because of weaker interties, uncertainties, various faults and disturbances. These LFEOs (0.2–3 Hz) are less in magnitude and are responsible for lower power transfer, increased losses and also threaten the stability of power system. An adaptive interval type-2 fuzzy sliding mode controlled power system stabilizer (AIT2FSMC-PSS) is presented to neutralize the LFEOs and enhance stability under uncertainties and external disturbances. The AIT2FSMC is a hybridization of type-2 fuzzy logic system (T2FLS) with conventional SMC to lower the chattering effect, enhance the robustness of reaching phase and improve system's performance. Here, T2FLS is used for estimating the unknown functions of SMC. A robust sliding surface is presented to keep the system in the desired plane and remain stable under disturbance conditions. A modified control law is proposed for selecting the control parameters and Lyapunov synthesis is used to make the error asymptotically converging to zero. The effectiveness of the AIT2FSMC-PSS is accessed in single and multimachine power systems subjected to various uncertainties and disturbances. Again, comparison of performance indices (PIs), eigenvalues, damping ratios, oscillating frequencies, integral time absolute error (ITAE), figure of demerit (FD) and frequency domain plots like Bode, root locus and Nyquist plots are also analysed to access the efficacy of the proposed stabilizer. The simulated responses, comparative study and frequency plots confirm the supremacy of the proposed AIT2FSMC-PSS in suppressing the LFEOs to lesser settling characteristics, offer stable performance and assure transient stability of power system as compared to other stabilizers. [ABSTRACT FROM AUTHOR]

The need for better-performing algorithms to solve real-world power systems engineering problems has always been a challenging topic. Due to their stochastic nature, metaheuristic algorithms can provide better results. Thus, they have a rising trend in terms of investigation. This paper is a further attempt to offer a better optimizing structure, therefore, aims to provide a better-performing algorithm both for designing an appropriate proportional–integral–derivative (PID) controller to effectively operate an automatic voltage regulator (AVR) system and extracting the optimum parameters of a power system stabilizer (PSS) employed in a single-machine infinite-bus (SMIB) power system. Therefore, the paper discusses the development of the Lévy flight-based reptile search algorithm with local search capability and evaluates its potential against challenging power systems engineering optimization problems. The Lévy flight concept is used for better exploration capability in the proposed algorithm, whereas the Nelder–Mead simplex search algorithm is integrated for further exploitation. The latter case is confirmed through 23 benchmark functions with different features using statistical and nonparametric tests. The superiority of the proposed Lévy flight-based reptile search and Nelder–Mead (L-RSANM) algorithm-based PID controller for the AVR system is demonstrated comparatively using convergence, statistical and nonparametric tests along with transient and frequency responses. Besides, it is also assessed against previously reported and different methods, showing further superiority for AVR system control. Furthermore, the extraordinary ability of the L-RSANM algorithm to design an efficient PSS employed in the SMIB power system is demonstrated, as well. In conclusion, the proposed L-RSANM algorithm is shown to be more capable to solve the challenging power systems engineering design problems. [ABSTRACT FROM AUTHOR]

The penetration of renewable-based converter-interfaced generation and flexible alternating current transmission systems significantly changes properties and dynamic characteristics of modern electric power systems, which leads to the need to take measures to ensure security of their operation. These measures may consist in using the capabilities of new penetrated units or in adapting conventional means. Such adaptation consists in reconfiguration of control systems, development of new systems or approaches to settings determination, which include tuning of automatic voltage regulators with power system stabilizers of conventional synchronous generation. This paper proposes a new approach to tuning of automatic voltage regulators, based on the use of the most complete and reliable information about processes in modern power systems. This approach allows to get settings that are most adequate to practical conditions of operation as part of power systems. For this purpose, the hybrid real-time power system simulator and concept of hybrid modeling are used, and within this paper, and the hybrid modeling tools necessary for the tuning process have been developed. The result of the study is a comprehensive assessment of the reliability of the simulation results obtained using the developed tools, which allows to conclude about the possibility of their application. [ABSTRACT FROM AUTHOR]

Dynamic frequency stability concerns are engendered in the modern electric power system due to the large penetration of low inertia inverter interfaced distributed generation (IIDG) into the utility grid. Therefore, inertial support is needed similar to the conventional synchronous generator. From recent studies, it was observed that frequency stability is considered as one of the major challenges for the system operators and is required to be alleviated. In this methodology, the virtual inertia (VI) concept is suggested as a promising solution to boost the inertial response of IIDG. Full state feedback through a robust linear quadratic regulator (LQR) is employed to find optimal inertia and damping coefficients to emulate VI in IIDG. These coefficients are used to evaluate the additional power required to provide inertia emulation by a virtual synchronous generator (VSG). To upgrade the performance index in LQR, a bacterial foraging optimization algorithm (BFOA) is suggested for optimal parameters (weights) selection in the problem search space. The proposed optimal controller ameliorates VI dynamics and brings system frequency faster to the nominal value and allows more penetration of IIDGs. Time-domain simulated results and observed test system eigenvalues corroborate the effectiveness of a proposed controller. Time-domain simulations have been obtained using MATLAB/Sim Power Systems toolbox, and the LINMOD function in MATLAB is used to linearize the suggested system. [ABSTRACT FROM AUTHOR]

A new attempt of employing salp swarm algorithm (SSA) to tackle the optimal power flow (OPF) problem is demonstrated in the current study. This aforementioned problem has four fitness functions to be optimized such as (1) the sum of generating units' fuel costs, (2) total network real power losses, (3) entire sum of voltage deviation of load buses, and (4) static voltage stability (VS) of electric power systems. At initial stage, these objective are solved one by one, and at a later stage, different vector objective functions are solved simultaneously by the SSA. The VS study based on a modal analysis is taken into consideration as an objective function. In this issue, the eigenvalues and eigenvectors of a reduced Jacobian matrix due to the reactive power change are figured. The smaller magnitude of eigenvalues indicates the vicinity to system voltage instability. As the magnitude of eigenvalues increases, the incremental voltage decreases, which means strong VS. The output active power of generating units, their voltages, transformers tap setting, and capacitor devices represent the search field. Two electric grids such as IEEE 57- and 118-bus electric networks are demonstrated to examine the performance of the SSA. The effectiveness of the SSA–OPF methodology is compared with that obtained by using other competing optimization methods. Furthermore, statistical performance measures comprising parametric and nonparametric tests are made and the simulation results are extensively verified which indicate a competition of the SSA with others algorithms in solving the OPF problem. [ABSTRACT FROM AUTHOR]

The synchrophasor data provided by wide-area measurement systems have potential applications in electric power systems such as the use of these measurements as control inputs of wide-area damping controllers (WADCs) for small-signal stability enhancement. However, synchrophasor data are particularly vulnerable to cyber attacks (such as denial-of-service attacks) that can cause communication link failures in a smart grid communication network and, consequently, compromise the power system stability. In order to reduce the impact of communication failures on the performance of a WADC, this paper proposes a method to design a WADC considering robustness to multiple operating points, time delays in the communication channels and possible permanent loss of communication signals in the input and the output of the controller (which may be due, e.g., to denial-of-service cyber attacks). The performance of the designed controller is evaluated using modal analysis and nonlinear time-domain simulations in one of the IEEE benchmark systems to validate the results: the Simplified 14-Generator Model of the Southeastern Australian Power System. [ABSTRACT FROM AUTHOR]

This paper aims at reviewing and summarizing the vast variety of techniques to improve transient stability of power systems. A qualitative comparison of the techniques is presented and the future outlook is discussed. The techniques are categorized into conventional and renewable-based techniques. Conventional techniques are well established and have been employed in the past. Renewable techniques investigate how generators based on renewable energy sources (RES) can contribute to improving stability. Moreover, it is distinguished between techniques applying preventive and emergency controls. For preventive control, re-dispatch of generators and series compensation are extensively used in practice, whereas for emergency control, a great share of the techniques aim at voltage support during fault conditions. Regarding preventive control using RES-based generation, one approach which temporarily increases the voltage set point of the units in order to increase the synchronizing power, is reported. Regarding renewable energy source-based emergency control, low-voltage ride-through capability including voltage support is a well-established method. Nevertheless, it is also highlighted that high-voltage ride-through capability plays a critical role. The findings show that distributed generation must be included in existing control schemes for preventive control, and new improvement techniques taking full advantage of them need to be developed. [ABSTRACT FROM AUTHOR]

Increasing in the scale and complexity of interconnected power systems was because of the growth of electricity demands, leading to multiple electromechanical oscillations despite having support of the power system stabilizer (PSS). Therefore, the dynamic performance of the existing networks should enhance. One type of flexible alternating current transmission system devices, namely the static var compensator (SVC), can be installed at the buses to maintain and/or control particular parameters of the electrical power system by exchanging capacitive and/or inductive current. However, the performance of SVC device highly depends upon its parameters, sizes, and suitable number and location in the power network. Hence, the optimal location for SVC has become a key issue; in this paper, we propose a novel approach for the suitable number and location for SVC by using critical energy analysis based on the Gramian matrices that the solution framework applied an algorithm based on the Lyapunov equations and the balanced realization technique. The optimal placement is determined by (1) analyzing the small-signal stability to seek number of feasible locations and (2) comparing these feasible locations by analyzing the transient stability through various simulation cases. The effectiveness of the proposed method is compared with the other optimal method and verified on the 39-bus New England system by the simulation results based on the power system simulation engineering (PSS/E) and MATLAB programs. The obtained result shows that the SVC is installed at the single or multi-location having the total maximum Gramian energy. [ABSTRACT FROM AUTHOR]

Power system stabilizers (PSSs) associated with generators are mandatory requirements for damping low-frequency oscillations of a multimachine power system. Nevertheless, PSSs work well at particular network configuration and steady-state conditions for which they were designed. Therefore, the aim of this paper is the design of a robust PSS able to ensure the stability of the system for a wide range of loading conditions and various faults with higher performance. The main motivation for this design is to simultaneously shift as much as could be possible the lightly damped and undamped system electromechanical modes, at different loading conditions and system configurations, into pre-specified zone in the s-plane called D-shape sector. Hence, the problem of robustly tuning the PSSs parameters is formulated as a multiobjective optimization problem (MOP) with an eigenvalue-based objective functions. An improved version of non-dominated sorting genetic algorithms (NSGAII) is proposed to solve this MOP. The performance of the proposed NSGAII-based PSS (NSGAII-PSS) under different loading conditions, system configurations and disturbances is tested and examined for different multimachine power systems. Eigenvalue analysis and nonlinear simulations show the effectiveness and robustness of the proposed controllers NSGAII-PSSs and their ability to provide efficient damping of low-frequency oscillations. [ABSTRACT FROM AUTHOR]

The identification of coherent areas is an important step to fortify the power system against the potential spread of cascading failures. This processing task helps to establish the preliminary strategies to implement online control methodologies that increase the power system reliability. In this regards, a methodology to identify coherent areas based on sliding power spectral density algorithm is presented in this paper. A coherency index is estimated from self- and cross-power spectral densities information in order to identify the coherent areas for a specific frequency related to an inter-area oscillation mode. In order to facilitate and automatize the process, an identification criterion based in the coherency index is proposed. This enables the proposed approach to be applied offline or online. In addition, the computation of the self-power spectral density using a sliding window opens the possibility to detect the onset of transient processes. Synthetic signals and two test power systems with different dynamic characteristics are used to evaluate the potential application in large systems. [ABSTRACT FROM AUTHOR]

This paper presents an optimized fractional order controlled cascaded synchronous buck-boost converter for a wave/ultra-capacitor (UC) hybrid energy system. Due to the irregular wave dynamics, the extracted energy from a wave energy converter (WEC) shows aperiodic voltage swells and sags. To eliminate the stochastic wave effects on the electrical side of the WEC, a power electronic interface scheme based on buck and boost converters named as cascaded synchronous buck-boost converter (CSBBC) is designed and a solar charged UC unit is integrated to the wave energy conversion system (WECS). The proposed CSBBC with UC stabilizes the DC-bus voltage and improves the energy utilization of WECS. The simulation and experimental results of the CSBBC and UC are investigated to show modeling success of these systems. In order to test the performance of the fractional order PID (FOPID) controller, a classical PID controller is also employed. The parameters of both controllers are tuned by flower pollination algorithm which utilizes an error-based fitness function. The results show that proposed power electronic system with UC unit works effectively to compensate irregular wave effects under different load and variable voltage tracking control cases. Also, it is emphasized that optimized FOPID controller provides higher performance than optimized PID controller in terms of transient and steady-state responses in control of both DC-bus and load voltages. [ABSTRACT FROM AUTHOR]

This paper presents genetic algorithm optimization method with a suitable objective function to determine optimum location and rated values of FACTS devices by taking into account changes in the power system load over time. In this study, annual daily load profile is considered as a whole instead of an instant load profile while looking for optimum size and location of FACTS devices. For this reason, to simplify the optimization procedure, a graph-based panelized objective function is developed, which can be used in a mixed integer search heuristic optimization technique. This paper focuses on the evaluation of the simultaneous use of thyristor controlled series capacitor and static VAR compensator. The proposed method allows including, in a simple way, the long term load profile in the planning stage to improve the power system performance using FACTS devices. After the optimization process, the performance of the proposed method has been tested on the IEEE-30 bus system with several annual test load profiles. The planning horizon is included in the optimization framework and the impact of planning horizon result is presented to compare with that of single load profile. The optimization strategy is shown to lead a significant reduction in the voltage and line violations under the long term test load profiles. [ABSTRACT FROM AUTHOR]

Computer simulations involving electric power systems need to be implemented upon structures that execute actions and which are able to reach specific proposals for switching and control. This very question is incorporated into the underlying proposal of this paper, which is shown through the presentation of an analysis performed using the software Alternative Transients Program, where the two main resources: MODELS language simulation and Transients Analysis of Control Systems were used in order to simulate the performance of the distributed generator controllers under different modes of operation and analyze their influence on the stability of an industrial plant. In those simulated cases, where disturbances were encountered, causing the opening and closing of switching commands, the regulators output signals are modified, thus controlling the behavior of the electrical and mechanical magnitudes associated with the generators. The obtained results show the performance of distributed generator controllers as adequate, in that they guarantee the stability of the industrial system, when responding to alterations in its operating conditions. [ABSTRACT FROM AUTHOR]

Hardware protection and control action are two kinds of low voltage ride-through technical proposals widely used in a permanent magnet synchronous generator (PMSG). This paper proposes an innovative clustering concept for the equivalent modeling of a PMSG-based wind power plant (WPP), in which the impacts of both the chopper protection and the coordinated control of active and reactive powers are taken into account. First, the post-fault DC link voltage is selected as a concentrated expression of unit parameters, incoming wind and electrical distance to a fault point to reflect the transient characteristics of PMSGs. Next, we provide an effective method for calculating the post-fault DC link voltage based on the pre-fault wind energy and the terminal voltage dip. Third, PMSGs are divided into groups by analyzing the calculated DC link voltages without any clustering algorithm. Finally, PMSGs of the same group are equivalent as one rescaled PMSG to realize the transient equivalent modeling of the PMSG-based WPP. Using the DIgSILENT PowerFactory simulation platform, the efficiency and accuracy of the proposed equivalent model are tested against the traditional equivalent WPP and the detailed WPP. The simulation results show the proposed equivalent model can be used to analyze the offline electromechanical transients in power systems. [ABSTRACT FROM AUTHOR]

Power system dynamic state estimation (DSE) has always been a critical problem in studying power systems. One of the essential parts of power systems are synchronous machines. In this work, we dealt with the problem of DSE of a synchronous machine by introducing a novel state space-based least mean fourth (SSLMF) algorithm. The rationale behind the proposed algorithm is the fact that a power system may encounter non-Gaussian disturbances/state errors and the least mean fourth algorithm is proven to be better in such environments. Moreover, we have also introduced a normalized version of the proposed algorithm, namely state space normalized least mean fourth (SSNLMF) algorithm to deal with the stability issue under Gaussian disturbances. Another motivation for developing the SSLMF algorithm is its simplicity as compared to other model-based nonlinear filtering algorithms such as Kalman filter, extended Kalman filter (EKF). Moreover, we also investigate the performance of the recently introduced state space least mean square (SSLMS). Performance of the SSLMF and the SSLMS is compared with existing EKF in both Gaussian and non-Gaussian noise environments. Extensive simulation results are presented which show superiority of the proposed algorithms, and hence, it verifies our rationale behind the work. [ABSTRACT FROM AUTHOR]

This paper is dedicated to investigate the influence of switching losses on Thyristor Controlled Series Compensator (TCSC) optimum allocation in power systems by using a Multi-Objective optimization technique. This allocation is performed with respect to minimization in system cost and voltage deviation as the objectives. For this purpose, cost of active power losses, investment cost of devices and active power generation cost in the peak load are considered to constitute the cost function as the economical objective. In addition, the paper considers interest rate in cost calculations to avoid impractical allocation results and imprecise solutions. The operational, technical and controlling constraints as well as load constraints are regarded in the allocation procedure. Also, the simulations are utilizing three unequal annual load levels to find optimum location and size of TCSC. The IEEE-14 Bus test system is used to validate the proposed method and show the importance of TCSC switching loss. Here, a novel optimization algorithm, Multi-Objective Artificial Bee Colony, is presented to provide Pareto optimal solutions. Also, an approach based on the goal attainment method combined with Genetic Algorithm is used to compromise between contradictory objectives and approach to the global optimum. [ABSTRACT FROM AUTHOR]

The smart grid is attracting more and more attention in electrical engineering for its promising features. However, huge challenges also exist in the implementations of the smart grid, such as high penetration of renewable energy resources, low carbon electricity and cyber-physical security, etc. In this paper, the latest progress of some research focuses and advance technologies in the development of smart grid is reviewed. [ABSTRACT FROM AUTHOR]

This paper is concerned with the use of subspace system identification techniques to derive a low-order black-box state-space model of a power system with many controllable devices. This is a multi-input multi-output open system model describing the power oscillatory behavior of the power system. The input signals are the controllable set points of the controllable devices, the output signals are the speed of some generators measured by a wide-area measurement system. This paper describes how to achieve and pre-process the data to use the subspace method to estimate and validate to finally assign an accurate model. This new approach can be used directly for the design of a centrally coordinated controller coordinating all the relevant controllable devices, with the aim to increase the damping of the modes in the system. Previously presented models, using input signals from controllable devices, use local measurements or output signals dependent on the actual operational point. The benefit of the presented method is that the used output signals are independent of the system state. This makes it possible to use a state-feedback controller, i.e., coordinated control. The presented method is applied in the Cigré Nordic 32-bus system including two high-voltage direct current (HVDC) links. The case study demonstrates that accurate low-order state-space models can be estimated and validated using the described method to accurately model the system's power oscillatory behavior. [ABSTRACT FROM AUTHOR]

Recently, fractional calculus has received extensive attention and research. Accordingly, there is an increasing interest in fractional-order (FO) dynamic systems and controllers. The widely used classical integer-order proportional-integral controller and proportional-integral-derivative controller are usually adopted in the load frequency control (LFC) and automatic generation control (AGC) to improve the dynamic response and to eliminate or reduce steady-state errors. This paper utilizes the FO controllers to improve stability and response of LFC and AGC system. The paper uses the integral of the time-weighted absolute error performance index for optimal controller design. The paper investigates LFC and AGC for both isolated and interconnected power systems and shows that FO controllers perform better than classical integer-order controllers in theses systems. [ABSTRACT FROM AUTHOR]

Power system stability enhancement via robust optimum design of power system stabilizers (PSSs) and thyristor controlled series capacitor (TCSC)-based stabilizers is thoroughly investigated in this paper. The design problem of PSS and TCSC-based stabilizers is formulated as an optimization problem where a reinforcement learning automata-based optimization algorithm is applied to search for the optimal setting of the proposed PSS and CSC parameters. A pole placement based objective function is considered to shift the dominant system eigenvalues to the left in the s-plane. For evaluation of the effectiveness and robustness of the proposed stabilizers, their performances have been examined on a weakly connected power system subjected to different disturbances, loading conditions, and system parameter variations. The nonlinear simulation results and eigenvalues analysis demonstrate the high performance of the proposed stabilizers and their ability to provide efficient damping of low frequency oscillations. In addition, it is observed that the proposed CSC has greatly improved the voltage profile of system under severe disturbances. [ABSTRACT FROM AUTHOR]

In recent years, power demand has increased substantially while the expansion of power generation and transmission has been severely limited due to limited resources and environmental restrictions. As a consequence, some transmission lines are heavily loaded and the system stability becomes a power transfer-limiting factor. Flexible AC transmission systems (FACTS) controllers have been mainly used for solving various power system steady state control problems. However, recent studies reveal that FACTS controllers could be employed to enhance power system stability in addition to their main function of power flow control. The literature shows an increasing interest in this subject for the last two decades, where the enhancement of system stability using FACTS controllers has been extensively investigated. This paper presents a comprehensive review on the research and developments in the power system stability enhancement using FACTS damping controllers. Several technical issues related to FACTS installations have been highlighted and performance comparison of different FACTS controllers has been discussed. In addition, some of the utility experience, real-world installations, and semiconductor technology development have been reviewed and summarized. Applications of FACTS to other power system studies have also been discussed. About two hundred twenty seven research publications have been classified and appended for a quick reference. [ABSTRACT FROM AUTHOR]

The evolution of self-organizing extrapolation controllers is described. Examples are given to illustrate the application of these controllers to electrical power systems. Prospects for the application of these controllers are examined. [ABSTRACT FROM AUTHOR]

In a deregulated power system uncertainty exists and lack of sufficient damping can lead to Low Frequency Oscillations (LFO). The problem can be addressed using robust Power System Stabilizers (PSS). In this paper, an optimal procedure to design a robust PID-PSS using interval arithmetic for the Single Machine Infinite Bus (SMIB) power system is proposed. The interval modelling captures the wide variations of operating conditions in bounds of system coefficients. In the proposed design procedure, simple and new closed loop stability conditions for an SMIB interval system are developed and are used to design an optimum PID-PSS for improving the performance of an SMIB system. The optimum PID-PSS is attained by tuning the parameters using the FMINCON tool provided in MATLAB. The robustness of the proposed PID-PSS design is validated and compared to other notable methods in the literature when the system is subjected to different uncertainties. The simulation results and performance error values show the effectiveness of the proposed robust PID-PSS controller. [ABSTRACT FROM AUTHOR]

Statistics shows that transients produced by lightning or momentary links with external objects, have produced more than 80% of faults in overhead lines. Reclosing of circuit breaker (CB) after a pre-defined dead time is very common however reclosing onto permanent faults may damage the power system stability and aggravate severe damage to the system. Thus, adaptive single-phase auto-reclosing (ASPAR) based on investigating existing electrical signals has fascinated engineers and researchers. An ASPAR blocks CB reclosing onto permanent faults and allows reclosing permission once secondary arc is quenched. To address the subject, there have been many ASPARs techniques proposed based on the features trapped in a faulty phase. This paper presents a critical survey of adaptive auto-reclosing schemes that have hitherto been applied to EHV transmission lines. [ABSTRACT FROM AUTHOR]

To deal with the high dimensionality and computational density of the Optimal Power Flow model with Transient Stability Constraints (OTS), a credible criterion to determine transient stability is proposed based on swing curves of generator rotor and the characteristics of transient stability. With this method, the swing curves of all generator rotors will be independent one another. Therefore, when a parallel computing approach based on the MATLAB parallel toolbox is used to handle multi-contingency cases, the calculation speed is improved significantly. Finally, numerical simulations on three test systems including the NE-39 system, the IEEE 300-bus system, and 703-bus systems, show the effectiveness of the proposed method in reducing the computing time of OTS calculation. [ABSTRACT FROM AUTHOR]