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A number of tuning rules have been reported in literature for unstable first order plus time delay processes. However, at least to the author knowledge most of the reported methods fail to give robust performance for process models with time delay equal to or greater than the process time constant. In this work, a robust tuning method based on the modified Smith predictor is proposed for unstable...
Proportional-integral (PI) controllers represent huge majority of all controllers applied in practice. Despite their broad use, different alternative solutions have been developed based on reconstruction and compensation of input, or output disturbances. Whereas a compensation of output disturbances reconstructed by a parallel plant model represents a key element of the well known internal model control...
This paper simulates the operation of automatic circuit recloser under the system ground fault condition using MODELS language in transient digital simulation EMTP-ATPDraw. Any other recloser operation schemes such as two fast-one delay or one fast-one delay can be modeled. In this paper the recloser model has been tested with two fast and one time delay operation schemes for both temporary and permanent...
Field Device Integration (FDI) is recently defined automation standard that provides a common platform to integrate and configure field devices that works on different protocols from different manufactures. The FDI standard incorporates the advantages of existing device integration technologies such as Field Device Tool (FDT) and Electronic Device Description Language (EDDL). This paper presents a...
A two-degree-of-freedom control scheme is proposed for enhanced control performance of integrating and unstable processes with time delay. The two controllers in the scheme are well placed to tune from the setpoint and disturbance. The design steps of these two controllers are independent. The H2 optimal control method is used to design the set-point tracking controller and an optimal internal model...
A two-degree-of-freedom control scheme is proposed for enhanced control performance of unstable processes with time delay. The two controllers in the scheme are well placed to tune from the setpoint and disturbance. The design steps of these two controllers are independent. The H2 optimal control method is used to design the set-point tracking controller and an optimal internal model control (IMC)...
This paper proposes a model based controller design by exploiting μ-synthesis for a network based system with time varying delay and the plant model uncertainty. Much research has investigated network system with time delay and both frequency-domain based and time domain based approaches have been proposed. In this paper, we firstly review the study on conservativeness of existing approaches for time...
This paper presents a disturbance rejection scheme for linear time delay systems subjected to both constant and single sinusoidal disturbances. Astrom's modified Smith predictor is employed to maintain good setpoint tracking performance. Disturbance rejection controller is designed via internal model control principle and implicitly incorporates a finite dimensional repetitive controller. The simulation...
In this paper, a new queuing model G (General arriving) /G (General Service) /1 (One Server)/ S (Number of limited buffers ) / FCFS (First Come, First Served) is proposed for integrated service with limited buffers in loop LAN. The model is built through reconstructed probability space in discrete time. According to the imbedded Markov chain theory and the generating function, a mathematical analysis...
This paper proposes a compensation scheme for both the time varying delay and the plant model uncertainty. As well known, time delay in feedback loop does not only weaken system performance, in worst-case situations it can cause system unstable. Conventional research treated the time varying delay as uncertain perturbation; however it restricts the performance of the system. In fact, the time delay...
In this paper, the threshold autoregressive modeling method is applied to build an accurate mathematical model for the time-delay from the controller to the actuator of NCS. A new time-delay compensation scheme is proposed based on this model. For this scheme, three networked controller design methods combined with the threshold autoregressive model to compensate the time-delay is discussed. At last,...
This paper describes a control method which compensates two factors in a network based control system: one is a time-varying delay on a network communication and the other is a modeling error due to uncertainty of the plant. For the time-varying delay, we model it with an accurate modeling by measuring the individual time delays, and utilize them for the model-based compensator. Because the time delay...
In this paper, a design method of discrete modified Internal Model Control (IMC) with parallel feedforward compensator (PFC) is proposed. Introducing PFC and a predictor as a plant model, we designed a control system with superior performance. In the simulation study, it is shown that the proposed method has a superior performance in a load disturbance response and robustness compared with the conventional...
It is known that the PID controller is ill-suited to handle time-delay processes, especially in applications with stringent control objectives to be met. For such purposes, deadtime compensators may be used. But such controllers still face resistance towards actual industrial applications due to their difficulties in implementation and realisation. In this paper, a PID solution involving setpoint...
Considering the characteristics of time delay, time variables and variable operation condition in process control system, The partial models are built based on the different operating points integrating fuzzy membership function with weighted sums to improve the traditional internal model control(IMC), and the fuzzy membership functions are obtained by recursion identification method. Then multiple...
Based on the mathematical model of flyback switching DC-DC converter in the continuous current mode and the simulation model under heavy loads, this paper presents a study of the steady-state power loss in the output diode, including the loss calculation models under three operational modes (voltage control, under-voltage, and over-current modes), the relations of the diode loss versus the input and...
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