Non-Linear Control of a Neutralisation Process

1971 ◽  
Vol 4 (9) ◽  
pp. T151-T157 ◽  
Author(s):  
P D Roberts
Keyword(s):  
Simulation Study ◽  
Digital Simulation ◽  
Linear Control ◽  
Attractive Alternative ◽  
Error Signal ◽  
Linear Controller ◽  
Linear Characteristic ◽  
Non Linear ◽  
On Line ◽  
Extra Parameter

The paper describes a digital simulation study of the application of a non-linear controller to the regulation of a single stage neutralisation process. In the controller, the proportional gain increases with amplitude of controller error signal. The performance of the non-linear controller is compared with that of a conventional linear controller and with the performance obtained by employing a linear controller with a linearisation network designed to compensate for the non-linear characteristic of the neutralisation curve. Although the performance of the non-linear controller is inferior to that obtained by employing a perfect linearisation network, its performance is still considerably superior to that obtained by using a conventional linear controller when operating at a symmetrical point on the neutralisation curve. In contrast to the linearisation network technique, the non-linear controller contains only one extra parameter and can be readily tuned on-line without prior knowledge of the neutralisation curve. Hence, it can be considered as an attractive alternative for the control of neutralisation processes.

scholarly journals Non-Linear Control for Variable Resistive Bridge Type Fault Current Limiter in AC-DC Systems

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 713 ◽  
Author(s):  
Md Alam ◽  
Mohammad Abido ◽  
Alaa Hussein
Keyword(s):  
Reactive Power ◽  
Effective Resistance ◽  
Linear Control ◽  
Control Technique ◽  
Fault Current ◽  
Fault Current Limiter ◽  
Linear Controller ◽  
Non Linear ◽  
Bridge Type ◽  
Current Limiter

This paper proposes a non-linear control-based variable resistive bridge type fault current limiter (VR-BFCL) as a prospective solution to ease the effect of disturbances on voltage source converter-based high voltage DC (VSC-HVDC) systems. A non-linear controller for VR-BFCL has been developed to insert a variable optimum resistance during the inception of system disturbances in order to limit the fault current. The non-linear controller takes the amount of DC link voltage deviation as its input and provides variable duty to generate a variable effective resistance during faults. The VSC-HVDC system’s real and reactive power controllers have been developed based on a current control loop where direct axis and quadrature axis currents are used to control the active and reactive power, respectively. The efficacy of the proposed non-linear control-based VR-BFCL solution has been proved with balanced as well as unbalanced faults. The results confirm that the oscillations in active power and DC link voltage have been significantly reduced by limiting the fault current through the insertion of an optimum effective resistance with the proposed control technique. The real time digital simulator (RTDS) has been used to implement the proposed approach. The performance of the proposed non-linear control based VR-BFCL is compared with that of traditional fixed duty control.

On-Line Analysis of a Non-Linear Control System Using Correlation Methods

1968 ◽  
Vol 1 (6) ◽  
pp. 222-225 ◽  
Author(s):  
R. E. Selway ◽  
D. Bell
Keyword(s):  
Optimal Control ◽  
Control System ◽  
Linear Control ◽  
Correlation Methods ◽  
Non Linear ◽  
On Line ◽  
Hybrid Computer ◽  
Non Linear System ◽  
M Sequences ◽  
Working Point

In non-linear control processes the application of optimal control generally leads to a solution which is difficult to implement. The problem is approached here by the use of a correlation method of continual tracking of the working point on the static and dynamic characteristics of the control system. A hybrid computer is utilised to compute the correlation functions and continually to identify and reoptimise about the working point using quasi-linearisation techniques. The non-linear system considered is a hyrdaulic servomotor of a type used in aircraft flight control systems. The three-level m-sequences used as test signals are injected into the system during normal operation and, since they are uncorrelated with any other signal, may have an extremely small amplitude compared with the normal working input signal. Optimal control in this instance is applied by the use of a phase compensation network with a variable bandwidth. The change of bandwidth required to satisfy the performance criterion is calculated on-line and used to optimise the system. A brief summary of correlation methods is presented together with the equation's governing identification and optimisation. The hybrid computer arrangement is described and a selection of typical results is shown and discussed. A note on the stability of the overall system as a system with time delays is included. In conclusion, the problems of time-variant dynamics on non-linear systems are considered. A proposed hybrid computer scheme is presented for this purpose in which the characteristics of the m-sequences are up-dated to match the identified time constants of the system.

Analysis and Simulation of Altimeter Performance for the Production of Ice Sheet Topographic Maps

1986 ◽  
Vol 8 ◽  
pp. 141-145 ◽  
Author(s):  
K.C. Partington ◽  
C.G. Rapley
Keyword(s):  
High Precision ◽  
Systems Analysis ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Data Interpretation ◽  
Topographic Maps ◽  
Error Signal ◽  
Tracking Systems ◽  
Tracking Mode ◽  
Non Linear

Satellite-borne, radar altimeters have already demonstrated an ability to produce high-precision, topographic maps of the ice sheets. Seasat operated in a tracking mode, designed for use over oceans, but successfully tracked much of the flatter regions of the ice sheet to ± 72° latitude. ERS-1 will extend coverage to ± 82° latitude and will be equipped with an ocean mode similar to that of Seasat and an ice mode designed to permit tracking of the steeper, peripheral regions. The ocean mode will be used over the flatter regions, because of its greater precision.Altimeter performance over the ice sheets has been investigated through a study of Seasat tracking behaviour and the use of an altimeter performance simulator, with a view to assessing the likely performance of ERS-1 and the design of improved tracking systems. Analysis of Seasat data shows that lock was frequently lost, as a result of possessing a non-linear height error signal over the width of the range window. Having lost lock, the tracker frequently failed to transfer rapidly and effectively to track mode. Use of the altimeter performance simulator confirms many of the findings from Seasat data and it is being used to facilitate data interpretation and mapping, through the modelling of waveform sequence.

Sign in / Sign up

Export Citation Format

Share Document