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IEE Proceedings D (Control Theory and Applications)

Volume 127, Issue 6, November 1980

Volumes & issues:

Volume 127, Issue 6

November 1980

Identification and optimal output control of a laboratory power system
  • Author(s): O.H. Abdalla  and  P.A.W. Walker
  • Source: IEE Proceedings D (Control Theory and Applications), Volume 127, Issue 6, p. 237 –244
  • DOI:  10.1049/ip-d.1980.0040
  • Type: Article
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  • p. 237 –244 (8)
    The paper describes the design of an optimal controller, based on output feedback, to provide integrated control of the exciter and prime mover of micro-synchronous-generator. Modelling of the control input-output measurement dynamics of the power system by an output prediction equation using least-squares analysis, is followed by multivariable control-system design based on discrete dynamic programmiing to minimise a quadratic performance index. This approach avoids any reference to the system state vector, which may contain states which are difficult to measure, and thus any need for state estimation techniques or the omission of unmeasurable states from the state feedback control law. The paper evaluates the effectiveness of this controller over a wide range of operating conditions, including dynamic and transient stability boundaries and 3-phase faults, with and without permanent line outage.
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Book review: Monotone Operators and Applications in Control and Network Theory
Fast-acting helical solenoid actuators
  • Author(s): A.H. Seilly
  • Source: IEE Proceedings D (Control Theory and Applications), Volume 127, Issue 6, p. 245 –249
  • DOI:  10.1049/ip-d.1980.0042
  • Type: Article
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  • p. 245 –249 (5)
    A new concept of solenoid actuator is described which enables its armature to achieve response times of faster than 1 ms irrespective of mass or force to be overcome. This is a short-stroke device and designs to date have been limited to 1 mm although larger strokes are possible. With conventional solenoids the larger and more powerful they are made the slower their response time. Hence only tiny solenoid actuators with very low forces have been possible when operating times below 1 ms were required. This is because its armature mass increases faster than the force generated in its working face area. In the helical solenoid actuator its construction is such that its armature mass increases directly in proportion to the force required for a given stroke, thus an increase in its size or power does not affect its response time provided that input power is increased in the same proportion to its size. This is achieved by using a two-start helix with its winding wound along the root of one thread and returning along the root of the adjacent thread, the armature consisting of a thin tube with an internal two-start mating thread.
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Book review: Introduction to Control Theory Including Optimal Control
Decomposition approach to problem of unit commitment schedule for hydrothermal systems
  • Author(s): L.F.B. Baptistella  and  J.C. Geromel
  • Source: IEE Proceedings D (Control Theory and Applications), Volume 127, Issue 6, p. 250 –258
  • DOI:  10.1049/ip-d.1980.0044
  • Type: Article
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  • p. 250 –258 (9)
    A method for determining the unit commitment schedule for hydrothermal systems using extensions of the Benders decomposition approach has been developed. The optimisation problem is partitioned in this paper into a stochastic nonlinear and a pure-integer nonlinear programming problem. The first problem, which represents the simultaneous economic dispatch of thermal and hydraulic power generating units, is solved by a feasible decomposition approach. The model minimises the total expected costs of start-up and unit operating costs subject to stochastic demand, spinning-reserve, and hydroplant, thermal and unit commitment constraints. Numerical results obtained for a small network are presented.
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Explicit self-tuning methods
  • Author(s): J.-J.J. Fuchs
  • Source: IEE Proceedings D (Control Theory and Applications), Volume 127, Issue 6, p. 259 –264
  • DOI:  10.1049/ip-d.1980.0045
  • Type: Article
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  • p. 259 –264 (6)
    A general scheme, which allows the analysis of self-tuning controllers of linear systems with constant but unkonwn parameters, is presented. The emphasis is on explicit self-tuning methods applied to a given class of single-input/single-output, discrete-time stochastic systems. These methods involve the combination of a system parameter identifier and a control law calculation algorithm. A specific (stochastic gradient type) identification algorithm is analysed in order to establish what kind of properties one can expect from the identifier part of such an adaptive control scheme. A general control law structure is then considered and it is shown that any identification algorithm satisfying the previously obtained properties, combined with any control law calculation algorithm fulfilling some quite weak conditions leaads to an overall adaptive system stable in some satisfactory stochastic sense, under an additional ‘stabilisability assumption’ on the estimated model of the system. This is summarised in a theorem which, we believe, should lead to new interesting results especially for non-minimum-phase systems. Similar approaches have been previously proposed for deterministic systems.
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Linear induction motors controlling carriages moving round a circular track
  • Author(s): B.E. Jones  and  B. Wilson
  • Source: IEE Proceedings D (Control Theory and Applications), Volume 127, Issue 6, p. 265 –271
  • DOI:  10.1049/ip-d.1980.0046
  • Type: Article
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  • p. 265 –271 (7)
    The paper describes a way of precisely controlling, in a noncontact manner, the position of conducting plates as they move between a series of separate linear induction motors. To establish the method, a circular rig of 0.7m diameter containing eight commercial thrust units driven from a single-phase mains supply has been used. Each carriage running on the circular track is provided with a reaction plate for actuation purposes and a digitally coded perspex strip for position detection. Each thrust unit has its own optical position detector and phase-angle controller, providing a positional control system operational over a 35° arc of the track. A common demand waveform drives all eight controllers so that a number of carriages (up to eight) can rotate continuously at speeds between 10 rev min−1 and 60 rev min−1 on the track, maintaining a fixed interspacing within ± 3 mm. Carriage momentum takes it from one thrust unit control region to the next. The carriages (of mass 1kg) can be started and stopped within a 10° arc of movement, while the displacement step response is 0.1 s. This development could lead to the production of a novel type of braiding machine having distinct advantages over existing types.
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Identification of nonlinear systems–a survey
Book review: Control and Co-ordination in Hierarchical Systems
Formula for output autocorrelation and spectrum of a Volterra system with stationary Gaussian input
Self-adaptive near-optimal control of diffusion equations
  • Author(s): A.S.I. Zinober
  • Source: IEE Proceedings D (Control Theory and Applications), Volume 127, Issue 6, p. 290 –295
  • DOI:  10.1049/ip-d.1980.0050
  • Type: Article
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  • p. 290 –295 (6)
    The self-adaptive near-optimal control of diffusion equations is described. The variable structure feedback design is independent of the initial conditions and the plant parameter values. Rather than identifying the precise parameter values by adaptive correction, the online self-adaptive closed-loop controller organises itself by identifying certain dynamic characteristics associated with sliding motion. Digital simulation results are presented for both linear and nonlinear systems, and the effect of parameter variations and external disturbances are discussed. The system responses are close to the time-optimal paths.
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Erratum: On the sensitivity of a system compensated by the inverse Nyquist array
Identification of the Volterra kernels of nonlinear systems

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