Proportional control

About: Proportional control is a research topic. Over the lifetime, 3756 publications have been published within this topic receiving 49050 citations.

Robustness of Parameter-Less Remote Real-Time Pressure Control in Water Distribution Systems

Abstract: One way of reducing water leakage, pipe bursts and water consumption in a water distribution system (WDS) is to manage the pressure to be as low as possible. This can be done by adjusting a pressure control valve (PCV) in real time in order to keep the pressure low and constant at a remote consumer location, by using a controller. When such smart infrastructure is implemented in a WDS, the choice of controller is important. Recently proposed controllers which use the flow rate in the PCV are more resilient to different WDS conditions than conventional proportional control. Here, the former controllers which adjust the head loss coefficient of the PCV are considered; either with a tunable parameter or parameter less. For two parameter-less controllers new mathematical expressions are derived for the deviation of the pressure from constant pressure in a WDS with one PCV. The deviation is proportional to the head loss over the PCV, which varies for different WDSs. Also, the deviation is proportional to the time-step between successive controller iterations. Hence the time-step can be chosen to reduce the deviation to a preselected level. Moreover, the deviation is proportional to the scale-independent rate of change of flow rate in the PCV. In addition, it is shown that for the two ‘constant flow’ controllers, the flow does not have to be known accurately. Hence, although the flow needs to be known, it can be known with significant uncertainty, enhancing the practical use of these controllers.

A proportional plus extended time-delayed feedback controller for a PWM inverter

Abstract: PWM current-mode single phase inverters are known to exhibit bifurcations and chaos when parameters vary. Our aim in this paper is to show how to apply a control method issued from chaos theory, in order to extend the stability range of a commonly used linear controller. To accomplish this aim, an extended time-delayed feedback controller (ETDFC) is used in conjunction with the proportional controller. An obvious advantage of this method is the robustness and ease of implementation because it does not require the knowledge of an accurate model but only the period of the target unstable periodic orbit (UPO).

Model Predictive Control of Polymer Electrolyte Membrane fuel cell with dead-end anode and periodic purging

Abstract: This paper proposes a model predictive control structure to attain performance requirements and to meet with actuator constraints. The goal is to maintain the differential pressure between the anode and cathode sides of a polymer electrolyte membrane fuel cell (PEMFC), at the inlet side of the stack, known as fuel overpressure, in a desired region. The effects of dynamic purging, nitrogen crossover, and load are included as disturbances. A proportional control valve is used as an actuator. Applying the pneumatic modeling technique, the behavior of a Ballard 3kW test station in a dead-end anode configuration is replicated and experimentally validated. To achieve a linear model, a nonlinear transformation is used to decompose the valve dynamic behavior. To evaluate the controller performance, numerical simulation is conducted using data from the experimental model. The results show the ability of the controller to compensate for all disturbances.

Temperature control strategies for radiant floor heating systems

Abstract: A dynamic model of a radiant floor heating (RFH) system useful for control analysis is developed. The overall model consists of a boiler, an embedded tube floor slab and building enclosure. The overall model was described by nonlinear differential equations, which were solved using finite numerical methods. The predicted responses from the model were compared with published experimental data. The comparisons were made covering a wide range of weather and operating conditions under several different control strategies. The model predictions compare well with the experimental data. The effective thermal capacity of the floor slab was found being an important parameter in calibrating the model results with the experimental data. Three different control strategies for improving the temperature regulation in RFH systems are proposed. These are: a multistage on-off control, an augmented constant gain control (ACGC) and a variable gain control (VGC). Simulation results show that the multistage control maintains zone air temperature close to the setpoint better than the existing on-off control scheme does. Likewise, ACGC gives good zone temperature control compared to the classical proportional control. A model based approach for updating the controller gains of the VGC is proposed. Both ACGC and VGC are shown to be robust to changes in weather conditions and internal heat gains. The advantage of the control strategies proposed in this thesis is that they eliminate the use of outdoor temperature sensor required in some existing control schemes. Being simple and robust, the multistage control scheme with two stages and the ACGC are good candidate controls for RFH systems.