Fast Output Sampling Technique Research Articles

Robust decentralized fast-output sampling technique based power system stabilizer for a multi-machine power system

Power-system stabilizers (PSSs) are added to excitation systems to enhance the damping during low-frequency oscillations. In this paper, the design of robust decentralized PSS for four machines with a 10-bus system using fast-output sampling feedback is proposed. The nonlinear model of a multimachine system is linearized at different operating points, and 16 linear state space models are obtained. For all of these plants, a common stabilizing state feedback gain, F, is obtained. A robust decentralized fast-output sampling feedback gain which realizes this state feedback gain is obtained using LMI approach. This method does not require all the states of the system for feedback and is easily implementable. This robust decentralized fast-output sampling control is applied to a nonlinear plant model of several machines at different operating (equilibrium) points. This method yields encouraging results for the design of power-system stabilizers.

Fault-tolerant spatial control of a large pressurised heavy water reactor by fast output sampling technique

A method is presented to design a spatial control system of a large pressurised heavy water reactor (PHWR) with the constraint that the closed loop system be stable even if one sensor or actuator has failed. Linear state models are obtained corresponding to the normal operating condition and different failure modes of the reactor. Each model is found to possess the two time scale property. Using similarity transformation each two time scale model is converted into a block diagonal form by which two subsystems, namely a fast subsystem and a slow subsystem, are easily obtained. State feedback is designed separately for the slow and the fast subsystems for each model. Then a composite state feedback gain is obtained from the state feedback gains computed for the slow and fast subsystems separately for each model. The composite state feedback so designed assigns the poles at arbitrary locations for the respective models. These composite state feedback gains are realised simultaneously by fast output sampling gains. Thus the states of the system are not needed for feedback purposes. An LMI formulation is used to overcome the undesired effects of poor error dynamics and noise sensitivity which are encountered if state feedback is realised exactly.

Spatial control of a large pressurized heavy water reactor by fast output sampling technique

In this paper a method is presented to design a controller for discrete two time scale system based on fast output sampling technique. Using similarity transformation the two time scale system is converted into a block diagonal form which is then partitioned into two subsystems, namely, a fast subsystem and a slow subsystem. Now state feedback controls are designed separately for the slow subsystem and the fast subsystem. Then a composite state feedback control is obtained from the state feedback controls designed for subsystems to assign the eigenvalues of the entire system at arbitrary locations. This composite state feedback gain is realized by using fast output sampling feedback gain. Thus the states of the system are not needed for feedback. But in practice there are two problems in realizing the state feedback gain exactly viz. poor error dynamics and noise sensitivity. So a linear matrix inequality formulation is used to overcome these undesired effects. The method has been applied to a large pressurized heavy water reactor (PHWR) for control of xenon induced spatial oscillations. A particular grouping of the state variables has been considered to decompose the system into the slow subsystem and the fast subsystem. Then fast output sampling fedback gains have been calculated. The efficacy of the control has been demonstrated by simulation of transient behavior of the nonlinear model of the PHWR.

Variable structure model following controller using non-dynamic multirate output feedback

The paper presents a new algorithm for a variable structure model following controller (VSMFC) design for discrete time systems using a fast output sampling technique. The reaching law approach is used to guarantee the sliding mode motion. This methodology is easy to implement since the method is based on output feedback. It is shown that the proposed fast output sampling variable structure model following controller (FOS VSMFC) gives the same results as obtained by state feedback VSMFC. To demonstrate the design technique a VSMFC is designed for the tip position control of a single flexible link. The simulation results show the effectiveness of the proposed method.