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Showing papers in "IEEE Transactions on Power Systems in 1997"


Journal ArticleDOI
TL;DR: In this article, a technique for answering the question of which generators are supplying a particular load, how much use each generator is making of a transmission line and what is each generator's contribution to the system losses is described.
Abstract: Because of the introduction of competition in the electricity supply industry, it has become much more important to be able to determine which generators are supplying a particular load, how much use each generator is making of a transmission line and what is each generator's contribution to the system losses. This paper describes a technique for answering these questions which is not limited to incremental changes and which is applicable to both active and reactive power. Starting from a power flow solution, the technique first identifies the busses which are reached by power produced by each generator. Then it determines the sets of buses supplied by the same generators. Using proportionality assumption, it is then possible to calculate the contribution of each generator to the loads and flows. The applicability of the proposed technique is demonstrated using a 30-bus example.

641 citations


Journal ArticleDOI
TL;DR: In this article, a new data processing method is proposed to estimate the proximity to voltage collapse in real-time, which employs only local measurements-bus voltage and load current-and calculates the strength of the transmission system relative to the bus.
Abstract: Estimating the proximity of power systems to voltage collapse in real-time still faces difficulties. Beside the data management and computational issues, any central-control method is subject to the reliability of long-distance data communications. In the paper, the authors describe a new data-processing method to estimate the proximity to voltage collapse. The method (code-named SMARTDevice, for Stability Monitoring And Reference Tuning Device) employs only local measurements-bus voltage and load current-and calculates the strength of the transmission system relative to the bus. The collapse occurs when the local load approaches this value. The method is simple enough so that it can be implemented in a numerical relay. The performance of SMARTDevice is compared against the conventional undervoltage relays. It is shown that the latter can misoperate while the new device does not. SMARTDevice is in fact a new breed of voltage relay whose setpoint is automatically tuned to the power system condition.

482 citations


Journal ArticleDOI
Janusz Bialek1
TL;DR: In this article, the authors proposed a simple method of transmission supplement charge allocation based on topological analysis of power flows in the network. But the method uses the MW-MILE methodology but analyses the share, not the impact of, individual loads and generators in line flows.
Abstract: This paper introduces a simple novel method of transmission supplement charge allocation based on topological analysis of power flows in the network. The method uses the MW-MILE methodology but analyses the share, not the impact of, individual loads and generators in line flows. This results in positive contributions from all the users hence rescinding the problem of counterflows.

454 citations


Journal ArticleDOI
TL;DR: An approach to parallelizing optimal power flow (OPF) that is suitable for coarse-grained distributed implementation and is applicable to very large interconnected power systems is presented.
Abstract: We present an approach to parallelizing optimal power flow (OPF) that is suitable for coarse-grained distributed implementation and is applicable to very large interconnected power systems. We demonstrate the approach on several medium size systems, including IEEE Test Systems and parts of the ERCOT system. Our simulations demonstrate the feasibility of distributed implementation of OPF. Rough estimates are made of parallel efficiencies and speed-ups.

400 citations


Journal ArticleDOI
TL;DR: In this article, linear and quadratic estimates to the variation of the loading margin with respect to any power system parameter or control are derived, and tests with a 118-bus system indicate that the estimates accurately predict the quantitative effect of altering the system loading, reactive power support, wheeling, load model parameters, line susceptance and generator dispatch.
Abstract: Power system loading margin is a fundamental measure of a system's proximity to voltage collapse. Linear and quadratic estimates to the variation of the loading margin with respect to any power system parameter or control are derived. Tests with a 118-bus system indicate that the estimates accurately predict the quantitative effect on the loading margin of altering the system loading, reactive power support, wheeling, load model parameters, line susceptance and generator dispatch. The accuracy of the estimates over a useful range and the ease of obtaining the linear estimate suggest that this method will be of practical value in avoiding power system voltage collapse.

380 citations


Journal ArticleDOI
TL;DR: In this article, a new interior point nonlinear programming algorithm for optimal power flow problems (OPF) based on the perturbed KKT conditions of the primal problem is presented. But the algorithm is not suitable for large-scale systems.
Abstract: This paper presents a new interior point nonlinear programming algorithm for optimal power flow problems (OPF) based on the perturbed KKT conditions of the primal problem. Through the concept of the centering direction, the authors extend this algorithm to classical power flow (PF) and approximate OPF problems. For the latter, CPU time can be reduced substantially. To efficiently handle functional inequality constraints, a reduced correction equation is derived, the size of which depends on that of equality constraints. A novel data structure is proposed which has been realized by rearranging the correction equation. Compared with the conventional data structure of Newton OPF, the number of fill-ins of the proposed scheme is roughly halved and CPU time is reduced by about 15% for large scale systems. The proposed algorithm includes four kinds of objective functions and two different data structures. Extensive numerical simulations on test systems that range in size from 14 to 1047 buses, have shown that the proposed method is very promising for large scale application due to its robustness and fast execution time.

364 citations


Journal ArticleDOI
TL;DR: In this paper, the authors analyzed field collected ambient noise by solving the Wiener-Hopf linear prediction equations to estimate the modal frequency and damping, and compared the results with results from a Prony analysis on a ringdown resulting from a 1400 MW brake insertion under the same operating conditions as the ambient data.
Abstract: Power system loads are constantly changing. Over a time-span of a few minutes, these changes are primarily random. The random load variations act as a constant low-level excitation to the electromechanical dynamics of the power system which shows up as ambient noise in field measured voltage, current and power signals. Assuming the random variations are white and stationary over an analysis window, it is theoretically possible to estimate the electromechanical modal frequencies and damping from the spectral content of the ambient noise. In this paper, field collected ambient noise is analyzed by solving the Wiener-Hopf linear prediction equations to estimate the modal frequency and damping. These estimates are then compared with results from a Prony analysis on a ringdown resulting from a 1400 MW brake insertion under the same operating conditions as the ambient data. Results show that estimates are consistent between the ambient and ringdown analysis indicating that it is possible to estimate a power system's electromechanical characteristics simply from ambient data. These results demonstrate that it may be possible to provide power system control and operation algorithms with a real-time estimate of modal frequency and damping.

345 citations


Journal ArticleDOI
TL;DR: In this paper, the authors use game theory to simulate the decision-making process for defining offered prices in a deregulated environment, which may be used by power pool coordinators to discourage unfair coalitions.
Abstract: The electric power industry is in transition to a deregulated marketplace for power transactions. In this environment, all power transactions are made based on price rather than cost. A regional power pool is noted as the most straightforward path to a deregulated electricity marketplace. However, many questions remain unanswered regarding the economics of power pool participation. In a deregulated energy marketplace, participants are interested in maximizing their own profits, regardless of the system-wide profits. It is perceived that competition will reduce the price of electricity for retail customers, however, the key issue for participants is related with the price definition to remain competitive. In this paper, the authors use game theory to simulate the decision making process for defining offered prices in a deregulated environment. The outcome of this study may be used by power pool coordinators to discourage unfair coalitions. A modified IEEE 30 bus power system is used as a deregulated power pool to illustrate the main features of the proposed method.

331 citations


Journal ArticleDOI
TL;DR: In this article, the authors provide a review of research problems as well as models related to the planning of substations and/or distribution feeders, and a discussion on relevant research opportunities is included.
Abstract: Power distribution planning is a complex task in which planners must ensure that there is adequate substation capacity (transformer capacity) and feeder capacity (distribution capacity) to meet the load demands. Decisions such as allocation of power flow, installation of feeders and substations, and procurement of transformers are costly ones which must be evaluated carefully. This paper provides a review of research problems as well as models related to the planning of substations and/or distribution feeders. Following a general discussion, we review existing research work under two major groups: planning under normal conditions, and planning for emergency. A discussion on relevant research opportunities is included.

329 citations


Journal ArticleDOI
TL;DR: In this article, a nonlinear optimization interior point (IP) method for the determination of maximum loadability in a power system is proposed, where most of the computational effort is taken by the formation and factorization of the augmented Hessian matrix of the IP algorithm.
Abstract: This paper proposes a nonlinear optimization interior point (IP) method for the determination of maximum loadability in a power system. Details of the implementation of pure primal-dual and predictor-corrector primal-dual IP algorithms are presented. It is shown that most of the computational effort of the algorithm is taken by the formation and factorization of the augmented Hessian matrix of the IP algorithm. The size of this matrix can be as large as ten times the number of buses in the system. Comparisons of the two IP implementations with large scale power systems with as many as 4000 buses are presented. It is shown that the IP algorithm constitutes an effective method for the determination of the maximum loadability in a power system.

309 citations


Journal ArticleDOI
TL;DR: In this article, the technical and economic issues of determining reactive power pricing structures in an open-access environment are explored, and several cost allocation methods for valuing reactive power are presented.
Abstract: This paper explores the technical and economic issues of determining reactive power pricing structures in an open-access environment. It is believed that reactive power pricing and management under open-access will depend upon two important developments: (1) the functional unbundling of facilities that support the reactive power and voltage control service, and (2) grid rules to facilitate the coordination between generation and transmission systems for reliable system operation. The paper discusses the characteristics of reactive power that must be considered in order to develop a framework for reactive power pricing and management. Several cost allocation methods for valuing reactive power are presented. Two workable reactive power pricing structures are also proposed. The first is based on performance standards and the second is based on the local reactive power market concept.

Journal ArticleDOI
TL;DR: In this article, an application of evolutionary programming (EP) to reactive power planning (RPP) has been proposed, which has been used in the IEEE 30-bus system and a practical power system.
Abstract: This paper proposes an application of evolutionary programming (EP) to reactive power planning (RPP). Several techniques have been developed to make EP practicable to solve a real power system problem and other practical problems. The proposed approach has been used in the IEEE 30-bus system and a practical power system. For illustration purposes, only results for the IEEE 30-bus system are given. Simulation results, compared with those obtained by using a conventional gradient-based optimization method, Broyden's method, are presented to show that the present method is better for power system planning. In the case of optimization of noncontinuous and nonsmooth functions, EP is much better than nonlinear programming. The comprehensive simulation results show a great potential for applications of EP in power system economical and secure operation, planning and reliability assessment.

Journal ArticleDOI
TL;DR: The IEEE 1995 Winter Power Meeting Panel Session on Challenges to optimal power flow (OPF) as discussed by the authors was based on material presented by the IEEE working group on operating economics, and the sessions covered an OPF user's perspective; challenges from a planning perspective; extended applications of OPF; OPF application in deregulated electricity market; challenges to on-line OPF implementation; and control OPF in EMS.
Abstract: This paper is based on material presented at the IEEE 1995 Winter Power Meeting Panel Session on Challenges to optimal power flow (OPF), sponsored by the IEEE working group on operating economics. The paper contains a brief summary of the session followed by summaries. The sessions covered are: an OPF user's perspective; challenges from a planning perspective; extended applications of OPF; OPF application in deregulated electricity market; challenges to on-line OPF implementation; and control applications of OPF in EMS.

Journal ArticleDOI
TL;DR: In this paper, a polynomial approximation with respect to time is applied to the waveform of the transients in estimating the inertia constant, and a simple model based on the idea of average system frequency is assumed to estimate the capacity of the generators.
Abstract: A procedure for estimating the inertia constant M(=2H) of a power system and total on-line capacity of spinning-reserve support generators, using transients of the frequency measured at an event such as a generator load rejection test, is presented. A polynomial approximation with respect to time is applied to the waveform of the transients in estimating the inertia constant, and a simple model based on the idea of average system frequency is assumed in estimating the capacity of the generators. Results of the estimation using the transients at 10 events show that the inertia constant of the 60 Hz power system of Japan is around 14 to 18 seconds in the system load base, and the capacity of the spinning-reserve support generators is 20 to 40% of the system load. The proposed procedure is expected to be tested by Kansai Electric Power Company with increased number of events. This effort will contribute to estimate and evaluate the dynamic behavior of the system frequency in loss of generation or load.

Journal ArticleDOI
TL;DR: In this article, a modified Newton method for radial distribution systems is derived in which the Jacobian matrix is in UDU/sup T/ form, where U is a constant upper triangular matrix depending solely on system topology and D is a block diagonal matrix.
Abstract: A modified Newton method for radial distribution systems is derived in which the Jacobian matrix is in UDU/sup T/ form, where U is a constant upper triangular matrix depending solely on system topology and D is a block diagonal matrix. With this formulation, the conventional steps of forming the Jacobian matrix, LU factorization and forward/back substitution are replaced by back/forward sweeps on radial feeders with equivalent impedances. Tests on several large distribution systems ranged from 490 to 1651 in nodes, 0.15 to 5.48 in r/x ratio and 0.0004 /spl Omega/ to 3.07 /spl Omega/ in line impedance have shown that the proposed method is as robust and efficient as the back/forward sweep method. The proposed method can be applied to other applications, such as state estimation. The proposed method can also be extended to the solution of systems with loops, dispersed generators and three phase (unbalanced) representation.

Journal ArticleDOI
TL;DR: This paper presents an alternative approach to distribution circuit state estimation using a probabilistic extension of the radial load flow algorithm while accounting for real-time measurements as solution constraint.
Abstract: Past work on distribution circuit state estimation has focused on the adoption of a transmission state estimator approach, without necessarily accounting for the specific requirement of a distribution circuit-based analysis. On distribution circuits, typically, there are very few available real-time measurements, and thus, researchers have treated customer load demand estimates as pseudo-measurements in a weighted-least-squares formulation. This can lead to convergence problems and also, the approach effectively assumes that all bus load demands are normally distributed (Gaussian) which may not be valid on distribution circuits. This paper presents an alternative approach to distribution circuit state estimation using a probabilistic extension of the radial load flow algorithm while accounting for real-time measurements as solution constraint. The algorithm which takes advantage of the radial nature of distribution circuits also accounts for other issues specific to distribution circuits. Namely, the algorithm accounts for nonnormally distributed loads, incorporates the concept of load diversity (load correlation) and can interact with a load allocation routine. The effectiveness of the algorithm is illustrated through comparisons made with Monte Carlo simulations.

Journal ArticleDOI
TL;DR: In this article, a framework for price-based operation is developed to assist students in understanding AGC implementation in the new market structure, where the proposed market structure is kept generic enough to capture all possibilities in marketing load following capability.
Abstract: This paper deals with automatic generation control (AGC) in a deregulated electric industry. Through the passage of new public utility regulatory policies, the Federal Energy Regulatory Commission (FERC) encourages an open market system for price based operation. The FERC has issued a notice of proposed rulemaking seeking comments on various ancillary services. One of these ancillary services is load following. This paper suggests the modifications required in the conventional AGC software to prepare students to study load following in price-based market operation. The details of implementing an academic power system are used to highlight the differences between the AGC operation in a vertically integrated industry (conventional paradigm) and a horizontally integrated industry (new paradigm). The future business environment for electric utilities is incompletely defined as of this writing. Therefore, a framework for price-based operation is developed to assist students in understanding AGC implementation in the new market structure. The proposed market structure is kept generic enough to capture all possibilities in marketing load following capability.

Journal ArticleDOI
TL;DR: In this article, the authors present a basic control system which enables the UPFC to follow the changes in reference values of the active and reactive power supplied from the outer system controller, based on the transformation of the three-phase power system to the rotating reference frame.
Abstract: A unified power flow controller (UPFC) is a typical FACTS device capable of instantaneous control of three power system parameters. This paper presents a basic control system which enables the UPFC to follow the changes in reference values of the active and reactive power supplied from the outer system controller. The analysis is based on the transformation of the three-phase power system to the rotating reference frame. As a step closer to a practical application of the UPFC, a modified control structure with a predictive control loop and precontrol signal for a DC-voltage control was designed. The new control system offers better stability and transient performance in comparison with the classical decoupled strategy, especially considering the harmonic distortion of the current being controlled. The derived basic control of the UPFC was tested with the NETOMAC program system.

Journal ArticleDOI
TL;DR: In this article, the main factors that affect the quality of the reduced models are discussed and the benefits of dynamic reductions are demonstrated for three large interconnected power system models for stability studies.
Abstract: This paper documents experience with applications of dynamic reductions to large power system models for stability studies. The main factors that affect the quality of the reduced models are discussed. The quality of reduced models and the benefits of dynamic reductions are demonstrated for three large interconnected power systems.

Journal ArticleDOI
TL;DR: These emerging optimization techniques (including expert systems, fuzzy logic, neural networks, analytic hierarchy process, network flow, decomposition method, simulated annealing and genetic algorithms) and their potential usage in solving the challenging generation expansion planning in future competitive environments in the power industry are described.
Abstract: Power system generation expansion planning is a challenging problem due to the large-scale, long-term, nonlinear and discrete nature of generation unit size. Since the computation revolution, several emerging techniques have been proposed to solve large scale optimization problems. Many of these techniques have been reported as used in generation expansion planning. This paper describes these emerging optimization techniques (including expert systems, fuzzy logic, neural networks, analytic hierarchy process, network flow, decomposition method, simulated annealing and genetic algorithms) and their potential usage in solving the challenging generation expansion planning in future competitive environments in the power industry. This paper provides useful information and resources for future generation expansion planning.

Journal ArticleDOI
TL;DR: In this paper, two feeder reconfiguration algorithms for the purpose of service restoration and load balancing in a real-time operation environment are described, which combine optimization techniques with heuristic rules and fuzzy logic for efficiency and robust performance.
Abstract: This paper describes two feeder reconfiguration algorithms for the purpose of service restoration and load balancing in a real-time operation environment. The developed methodologies combine optimization techniques with heuristic rules and fuzzy logic for efficiency and robust performance. Many of practical operating concerns of feeder reconfiguration and the coordination with other distribution automation applications are also addressed. The developed algorithms have been implemented as a production grade software. Test results on PG&E distribution feeders show that the performance is efficient and robust.

Journal ArticleDOI
TL;DR: In this paper, the authors developed simple but accurate continuous-time, large-signal dynamic models for a thyristor-controlled series capacitor (TCSC) based on the representation of voltages and currents as time-varying Fourier series, focusing on the dynamics of the short-term Fourier coefficients.
Abstract: This paper develops simple but accurate continuous-time, large-signal dynamic models for a thyristor-controlled series capacitor (TCSC). The models are based on the representation of voltages and currents as time-varying Fourier series, and focus on the dynamics of the short-term Fourier coefficients. Truncating the series to keep only the fundamental components provides a natural dynamic generalization of the familiar quasi-static phasor representation. Systematic simplifications or refinements of their fundamental phasor dynamics model yield a variety of other models. The authors establish that even the simplest of these models predicts the dynamic behavior of the TCSC very accurately. Their phasor models provide a powerful basis for simulation, more than an order of magnitude faster than detailed time-domain circuit simulation. The phasor models present an attractive alternative to sampled-data models, having the advantages of simpler representation, modularity and direct compatibility with the phasor models that are routinely used to represent the dynamics of generators and other power system components.

Journal ArticleDOI
TL;DR: In this article, the authors discuss various methods based on power network partitioning and voltage stability indices to accelerate the computation of voltage collapse points using continuation techniques and propose a predictor-corrector methodology based on this index and the continuation method.
Abstract: This paper discusses various methods based on power network partitioning and voltage stability indices to accelerate the computation of voltage collapse points using continuation techniques. Partitioning methods derived from right eigenvector and tangent vector information are thoroughly studied, identifying limitations and probable application areas; a mixed partition-reduction technique is then proposed to reduce computational burden. Also, tangent vectors are used to define a clustering method for the identification at any operating condition of the critical area at the collapse point, and a new voltage stability index is defined based on the identification of this critical area. Finally, a predictor-corrector methodology based on this index and the continuation method is proposed for fast computations of voltage collapse points. All the different methods are compared based on the results obtained for the IEEE 300-bus test system, and a methodology is recommended based on its prospective computational savings.

Journal ArticleDOI
TL;DR: In this article, the authors have interviewed employees working with generation planning at the eight largest power producers in Sweden and found five aspects causing start-up costs: loss of water during maintenance, wear and tear of the windings due to temperature changes during the start up, wear-and-tear of mechanical equipment during the starting-up, malfunctions in the control equipment, and loss-of-water.
Abstract: This paper is about start-up costs of hydro power units. In the introduction we address three questions about start-up of hydro power units: what causes the costs in the start-up? How much does a start-up cost? How do start-ups effect the short-term scheduling strategies of power producers in Sweden? In order to answer these questions, we have interviewed employees working with generation planning at the eight largest power producers in Sweden. We found five aspects causing start-up costs: loss of water during maintenance; wear and tear of the windings due to temperature changes during the start-up; wear and tear of mechanical equipment during the start-up; malfunctions in the control equipment during the start-up; and loss of water during the start up. The aspects causing the largest costs are maintenance due to the wear and tear and the unavailability and personnel costs due to malfunctions in the control equipment. The cost of lost water is usually small. Our conclusions are the following: start up cost will depend on the nominal power of the unit and the unit model; the majority of the power producers consider start-ups in their planning; there is a need for better knowledge about start-up cost; and there is a need for planning software which considers start-up costs of hydro units.

Journal ArticleDOI
TL;DR: In this article, a ranking-based search method employing analytical information obtained from three-phase power flow simulations is designed to restore service to as many priority customers as possible while maximizing the amount of total load restored and minimizing the number of required switch operations.
Abstract: A fast, effective service restoration method is designed for large-scale distribution systems with priority customers. The service restoration problem is formulated as a constrained multi-objective optimization problem. A ranking-based search method employing analytical information obtained from three-phase power flow simulations is designed to restore service to as many priority customers as possible while maximizing the amount of total load restored and minimizing the number of required switch operations. The proposed method is designed with consideration to networks which have predominantly manual switches. Comprehensive simulation results of the search method, including priority customers, single and multiple faults and multiple out-of-service areas are presented for a 416 bus distribution network.

Journal ArticleDOI
TL;DR: In this article, a new unit commitment method based on a decommitment procedure for solving the power system resource scheduling problem is introduced. But the method is based on dynamic programming according to some specified economic criteria.
Abstract: This paper introduces a new unit commitment method based on a decommitment procedure for solving the power system resource scheduling problem. From an initial schedule of all available units committed over the study period, a 'one-at-a-time' unit decommitment is accomplished by dynamic programming according to some specified economic criteria. The decommitment process continues until no further reduction in total cost is possible, or the unit schedules of two consecutive iterations over the time period remain unchanged without any violation of the spinning reserve constraint. Two criteria for decommiting a unit are introduced and described in detail. Comparisons of the proposed unit commitment method with the Lagrangian relaxation (LR) approach and Fred Lee's sequential unit commitment method (SUC) demonstrate the potential benefits of the proposed approach for power system operations planning.

Journal ArticleDOI
TL;DR: In this article, a new method for energy loss reduction in distribution networks is presented based on known techniques and algorithms for radial network analysis-oriented element ordering, power summation method for power flow, statistical representation of load variations and a recently developed energy summation algorithm for the computation of energy losses.
Abstract: A new method for energy loss reduction in distribution networks is presented It is based on known techniques and algorithms for radial network analysis-oriented element ordering, power summation method for power flow, statistical representation of load variations and a recently developed energy summation method for the computation of energy losses These methods, combined with the heuristic rules developed to lead the iterative process, make the energy loss minimization method effective, robust and fast It presents an alternative to the power minimization methods for operation and planning purposes

Journal ArticleDOI
TL;DR: In this article, a Monte Carlo simulation is used to select regions of the state space where loss of load states is more likely to occur, and these regions are isolated by performing state space decomposition to remove coherent acceptable subspaces.
Abstract: This paper presents a method of computing the reliability indices of a composite generation-transmission system by performing Monte Carlo simulation selectively on those regions of the state space where loss of load states are more likely to occur. These regions are isolated by performing state space decomposition to remove coherent acceptable subspaces. It is shown that this method results in a significant reduction in the number of sampled states, thereby reducing the computational effort required to compute the system and bus indices. The method assumes a DC flow model, and is tested using the IEEE Reliability Test System. The proposed method is not intended to replace existing variance reduction techniques; in fact, such techniques may be used in conjunction with the proposed method to further improve its efficiency.

Journal ArticleDOI
TL;DR: The PSA algorithm proposed in the paper has shown significant improvements in solution quality for the largest of the test networks, and the conditions under which the parallel algorithm is most efficient are investigated.
Abstract: The simulated annealing optimization technique has been successfully applied to a number of electrical engineering problems, including transmission system expansion planning. The method is general in the sense that it does not assume any particular property of the problem being solved, such as linearity or convexity. Moreover, it has the ability to provide solutions arbitrarily close to an optimum (i.e. it is asymptotically convergent) as the cooling process slows down. The drawback of the approach is the computational burden: finding optimal solutions may be extremely expensive in some cases. This paper presents a parallel simulated annealing (PSA) algorithm for solving the long-term transmission network expansion planning problem. A strategy that does not affect the basic convergence properties of the sequential simulated annealing algorithm have been implemented and tested. The paper investigates the conditions under which the parallel algorithm is most efficient. The parallel implementations have been tested on three example networks: a small 6-bus network; and two complex real-life networks. Excellent results are reported in the test section of the paper: in addition to reductions in computing times, the PSA algorithm proposed in the paper has shown significant improvements in solution quality for the largest of the test networks.

Journal ArticleDOI
TL;DR: In this paper, the transient stability of power systems is investigated using a new analytical tool, where trajectory sensitivity functions of the post-fault system with respect to parameters are computed instead of computing the sensitivities of energy margins.
Abstract: The transient stability of power systems is investigated using a new analytical tool. Instead of computing the sensitivities of energy margins, trajectory sensitivity functions of the post-fault system with respect to parameters are computed. The goal is to find how sensitive the trajectories of each state are to variations in system parameters. When the system becomes more stressed, the state trajectories become more sensitive to variations in parameters. Thus these trajectory sensitivities can be used as a measure of system security. This concept is illustrated on the IEEE single- and seventeen-machine systems, and it is shown that dynamic sensitivity functions can also be applied to systems of differential-algebraic equations where the TEF method has limitations.