摘要:

A computationally efficient procedure for identifying the structure and parameters of a linear discrete-time SISO system is presented. The procedure is based upon a new computational technique of parameter estimation, using the instrumental variables, that eliminates a number of redundant computations and does not require explicit evaluation of the instrumental variables. The structure determination is aimed at providing a combination of low residual error, low output error and low parameter estimation error. Application of the proposed procedure on simulated, as well as real, data is reported.

DOI:10.1049/ip-d.1985.0008

出版商:IEE    

年代:1985

数据来源: IET

摘要:

In the paper, transient stability analysis of anN-machine power system is carried out using the decomposition-aggregation method. In the study, transfer conductances, mechanical damping, electromagnetic damping and speed governor action are taken into consideration. The system decomposition is performed so that every subsystem includes three machines, instead of only two machines as for the pair-wise decomposition.The system mathematical model is derived and decomposed into (N– l)/2 sixth-order and one second-order interconnected subsystems. A vector Lyapunov function, whose elements are Lyapunov functions of the free (disconnected) subsystems, is constructed and used for the system aggregation.A seven-machine power system is used as an illustrative example, and an asymptotic stability domain estimate is determined for the system. It is found that the proposed decomposition scheme can lead to a considerable reduction in the conservativeness of the decomposition-aggregation method. It is found also that the pair-wise decomposition-aggregation approaches developed so far are not suitable for stability analysis of largescale power systems.

DOI:10.1049/ip-d.1985.0009

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The robustness of decentralised output control designs subject to nonlinear and linear perturbations in the system sensors is studied. Bounds on simultaneously acting nonlinearities are established, and it is shown that it is possible to calculate a sector such that system stability is assured. The suggested approach is not crucially dependent on any particular method for decentralised system design. New relationships are established between perturbation bounds and dominant poles of the nominal closed-loop system, thus helping a designer to select an appropriate degree of stability to attain a robust design. The theory is applied to characterise the robustness properties of a power system example, which employs five DC terminals to damp out inter-area oscillations owing to the AC power system dynamics.

DOI:10.1049/ip-d.1985.0010

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The solution to a linear quadratic stochastic optimal control problem is obtained for a discrete-time system. The performance criterion to be minimised includes the usual error and control weighting terms but has, in addition, the norms of the sensitivity and complementary sensitivity weighting matrices. The conditions for optimality are derived in the time-domain and the Wiener-type solution is obtained by transforming these conditions into thez-domain. A polynomial system description is then introduced so that the controller may be expressed in terms of the solution of diophantine equations. This is a more convenient form for computation of the controller.

DOI:10.1049/ip-d.1985.0011

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A refined design method, based upon known principles, is presented for the design of sampled-data SISO control systems. Based upon the Fourier analysis of a sampled signal and the Padé approximation, a sampled-data system may be approximated by a pseudo-continuous-time (PCT) control system. This approximation of a sampled-data system permits the use of continuous-time domain methods for designing cascade and/or feedback controllers based upon step-response specifications. When the rules governing the use of the Padé approximation and the Tustin transformation are satisfied, the PCT approach is a valuable technique for the design of sampled-data control systems, especially when the sampling timeTis much smaller than 1 s. ForT< 1 s, the accuracy needed in performing the calculations in thez-domain increases asTdecreases. The same degree of accuracy is not required while designing the controller in thes-plane. A design technique based upon the use of the PCT system is presented along with examples. The associated controller implementation problems are discussed.

DOI:10.1049/ip-d.1985.0012

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The design of analogue and digital controllers for a gas-turbine-powered, controllable pitch propeller marine propulsion plant, which displays nonminimum phase characteristics, is considered. Rosenbrock's multi-variable system theory is used to guide the development of control schemes that do not aggravate the non-minimum phase problems of the system.

DOI:10.1049/ip-d.1985.0013

出版商:IEE    

年代:1985

数据来源: IET