Steady-state Performance Of System Research Articles

Variable-structure facts controllers for power system transient stability

Nonlinear, variable-structure control theory is employed for series capacitor control and braking resistor control to improve the transient stability of a single machine infinite-bus (SMIB) system. A related simulation showed that variable-structure control of the series capacitor (SC) and braking resistor is effective for enhancement of power system steady-state performance and transient stability. Good transient response and high transmission limits were obtained. For the idealized control, only two switching applications are required, which suggests that the controller will be easily realized and reliable. The research reported suggests that variable-structure control can be used effectively for transient stability control of power systems. >

Extension of linear quadratic optimal control theory for mixed backgrounds

The problem of finding an optimal controller, while both deterministic and stochastic signals are present in the feedback system, is addressed. A general framework is developed to solve the above problem and to unify conventional frequency domain LQ and LQG optimal control theories. Both the system transient and steady-state behaviours are considered and the exact tracking of the arbitrary reference signal is guaranteed. The decomposition of a mixed signal into the deterministic and stochastic parts gives a chance to investigate the effect of the weighting factors, which were specified in the cost function, on the compromise between transient and steady-state system performance. The solution, which characterizes the structure of the optimal controller, results in a set of independent diophantine equations, instead of a set of coupled ones. Moreover, the number of equations can be reduced under weak conditions. Finally, both transient command tracking and steady-state noise rejection capabilities can be optimized simultaneously by using a two-parameter control scheme.

Steady-state modeling, analysis, and performance of transistor-controlled AC power conditioning systems

Steady-state modeling, analysis, and solution of transistor-controlled systems are developed and experimentally verified over a wide range of operation. General features of the system performance and the effects of the chopping frequency on the performance parameters and harmonic generation are thoroughly investigated. Over most of the control range, and for chopping frequencies in the order of several hundred hertz and higher, it is demonstrated that the harmonic contents of the load current are almost negligible, providing highly desired operating conditions for many applications where the fundamental current is the only useful component. >

A comment on the steady-state performance of multistate monotone systems

A comment on the steady-state performance of multistate monotone systems

A comment on the steady-state performance of multistate monotone systems

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A finite capacity queueing model with primary and secondary jobs

We consider a queueing model consisting of a primary buffer of capacity K and a secondary buffer of capacity N. Upon completion of the primary service, customers enter the secondary buffer for one additional service with probability p, 0 ⩽ p ⩽ 1, or leave the system with probability q = 1 − p. The server exhaustively processes the jobs from the secondary buffer whenever the primary buffer becomes empty or the secondary buffer fills up. The service times of the primary customers are assumed to follow a phase type distribution and those of the secondary jobs follow an exponential distribution with parameter μ 2. Customers arrive to the system according to a homogeneous Poisson process of rate λ. Using Markov chain theory, we discuss numerically stable algorithms to compute various steady-state system performance measures such as throughput, the fraction of time the server is busy, the fraction of time a primary customer is blocked, the fraction of time new customers are lost, expected numbers of customers waiting in the primary and secondary buffers. A number of numerical examples are presented.

Reference frame analysis of a slip energy recovery system

Until the late 1970s the performance of a slip energy recovery system of an induction motor was predicted analytically by means of steady-state power balance relationships. Here, reference frame theory is used to establish the equations which can be used to predict adequately the dynamic and steady-state performance of a slip energy recovery system. The steady-state performance as predicted from this analysis is compared with that predicted from computer simulation. The errors of a previously published approach are discussed and the inaccuracy in predicting the steady-state torque-speed characteristics is illustrated. The stage is now set to develop linearized, small displacement equations which can be used for control system design.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis of production line systems with two unreliable machines with phase type processing timesand a finite storage buffer

We consider a production line system consisting of two machines separated by a finite buffer. The machines have exponential failure and repair times. Using phase type distributions to model the processing times of the machines, we develop computationally tractable algorithms for computing the steady-state probabilities and various system performance measures. We also discuss a number of unintuitive numerical results and examples.

Ammonia/water absorption cycles with relatively high generator temperatures

The advent of evacuated tubular collectors, with their capacity for delivering heat in excess of 100°C at reasonable efficiency, has prompted investigation of the potential for absorption cycles employing higher generator temperatures than usual. The single-stage cycle and two high-performance cycles, termed the fat single-stage cycle and the two-stage cycle, are analyzed, with the single-stage and the two-stage cycles appearing to have the better prospects for incorporation into systems. Using improved heat transfer equipment which is under development, COPs of the order of 0.8 ought to be possible for single-stage cycles, and 1.3 for two-stage cycles, at peak generator temperatures of the order of 100 and 170°C respectively. The improved performance of the two-stage cycle should permit an improvement in overall steady-state system performance when this cycle is used in conjunction with evacuated tubular collectors, at the cost of increased system complexity.

Autonomous area generation control of interconnected power systems

The paper presents a new design procedure of an autonomous area regulator for automatic generation control (a.g.c.) of interconnected power systems. The regulator is of proportional-plus-integral type. It applies the basic concept of optimal linear regulators, using a reduced number of measurements from its own power area, as in the conventional control schemes. It is found that both the regulator structure and the steady-state system performance are the same as in the case of conventional control, with significant improvement of system transients. These features are advantageous from the implementation point of view, compared to the previously suggested linear regulator schemes that required the transmission of some measurements from neighbouring areas. The paper gives an analytical derivation of the autonomous a.g.c. system design and some digital simulation studies performed on a linearised state-space model of a 2-area interconnected powersystem.

Mutual Synchronization Properties of a System of Two Oscillators with Sinusoidal Phase Detectors

Mutual synchronization between two geographically separated phase-locked oscillators is investigated for two different interconnection methods. This includes the so-called single-ended (uncompensated delay) and the double-ended (compensated delay) methods. Explicit formulas for determining the steady-state frequency and phase errors are developed for both methods. Necessary conditions for the existance of a synchronous state are derived in terms of basic system parameters. Finally, a comparison Of the methods of oscillator interconnection is made as a function of the uncompensated channel delays. Graphical results are presented which are useful in determining steadystate system performance.

A Technique for the Analysis of Repairable Redundant Systems

A new analytical technique is presented for evaluating the steady-state performance of large repairable systems which cannot be described in terms of series-parallel subsystems. The method, which is based on a novel combinatorial algorithm, is used to calculate the frequency of failures and expected failure durations at each node in networks of repairable devices. The networks may have multiple input and output nodes, but the uptimes and downtimes of the devices in the network are assumed to be exponentially distributed and independent. To demonstrate the usefulness of the technique for large-scale networks of general configuration, the solution of a sample problem using a pilot computer program is also included.

Harmonic Torque and Speed Pulsations in a Rectifier-Inverter Induction Motor Drive

A method of predicting the 6th-harmonic electromagnetic torque of an induction motor arising from a rectifier-inverter power source is presented. This study includes both the effects of harmonic variation rotor speed and inverter voltage. Although only the 6th harmonic is considered, it is shown that this is sufficiently accurate to predict steady-state system performance for practical speed ranges and system parameters. This investigation reveals that the 6th-harmonic electromagnetic torque pulsation may, at low frequencies, be significantly greater than that predicted by a constant speed, constant voltage analysis heretofore employed, and may materially affect the performance of the system.

Aspects of Adaptive Optimal Steady-State Control

The paper extends and modifies an approach to adaptive optimal control problems proposed by Kulikowski. The emphasis at the outset is placed upon optimizing the steady-state system performance in which the desired output of the plant is a periodic function of time. The formulation for type-one plants is modified to include the optimization of the total amount of input accumulation, s=∫−∞t0u(τ)dτ, which is present at the beginning of each period of steady-state operation.