Showing papers by "Jihong Wang published in 2013"

Study of a New Strategy for Pneumatic Actuator System Energy Efficiency Improvement via the Scroll Expander Technology

Abstract: Although pneumatic actuators have been widely used in industry and other application areas, its weakness in low-energy efficiency is well known. Aiming for energy efficiency improvement, this paper presents a new hybrid pneumatic system that will recover energy from the exhaust compressed air through a scroll expander. The scroll expander drives a generator to convert the exhaust compressed air energy to electrical energy; thus, the proposed system is entitled “pneumatic-electrical” system. A closed-loop coordinate control strategy is engaged and proven to be essential in maintaining proper actuator operation status, while the scroll expander is connected in. The overall system mathematical model is derived and simulation results are presented in this paper. A test rig is set up to verify the feasibility of the proposed system structure. Both simulation and test results indicate that the proposed scheme is realistic and work well.

Comparison of two magnetic saturation models of induction machines

Abstract: The paper considers two models of induction machines accounting for magnetic saturation. The first is a systematically-designed model based on fundamental principles, while the second is a simplified model that neglects certain terms in the first model. The paper shows that both models predict the same responses in the linear region, as well as in the nonlinear region but only for steady-state operation. To investigate the possible superiority of one model over the other, the paper considers the measurement of transient responses where the models predict different behaviors. Experimental conditions are planned by computing the eigenvalues of the linearized systems and selecting conditions with maximal differences in settling time. Surprisingly, however, the experimental data shows relatively little differences between the predictions of the models and fails to favor one model over the other.

Model of a self-excited induction generator for the design of capacitor-controlled voltage regulators

Abstract: The systematic design of voltage regulation systems for self-excited induction generators requires the development of a control-oriented model. The paper considers the situation where the peak magnitude of the stator voltages is regulated through adjustable capacitors connected to the windings. A transfer function model is difficult to obtain, due to the strong nonlinearity of the self-excitation phenomenon, and to unconventional features of the problem. Nevertheless, the paper succeeds in computing a transfer function relating small deviations of the capacitance to small deviations of the voltage magnitude using a clever choice of reference frame. The linearized system is found to be stable for all operating points under consideration, and the eigenvalues of the system predict rapidly-decaying oscillatory transients combined with a slower exponentially decaying component. Results of simulations of the full nonlinear model and of the linearized system demonstrate the validity of the approximation for small deviations. Experimental results also show a good match between measured data and the identified model.

Development of a simulation model of a windshield wiper system for Hardware in the Loop simulation

Abstract: In order to compete effectively in the automotive industry, vehicle manufacturers employ advanced simulation techniques to assist in their product development. Hardware-in-the-Loop (HIL) simulation is a technique widely used by vehicle manufacturers in the development and testing of their Electronic Control Units (ECU), which can number up to 100 in modern vehicles. To carry out HIL testing on the ECUs, accurate simulation models of the sensors and actuators connected to the ECUs are required. The models must also be capable of simulating in real-time to be suitable for HIL testing. This paper presents the development of a Jaguar Land Rover windshield wiper system for use in HIL testing. An off-line physical model is first developed and validated. The model is capable of being parametized to capture design updates quickly without the need for waiting for new prototypes, speeding up the testing cycle. The physical model is then simplified to produce a real time capable model of the wiper system. The simplified model has a significantly faster simulation speed than the off-line physical model. It is capable of being simulated in real time but is less accurate than the physical model. Genetic algorithms have been used to identify the parameters of the model. The on-line model is then implemented in a HIL facility to be used for ECU testing by Jaguar Land Rover.

Dynamic modelling and simulation study of Texaco gasifier in an IGCC process

Abstract: Integrated gasification combined cycle (IGCC) is considered as a viable option for low emission power generation and carbon-dioxide sequestration. The simulation of the whole IGCC process is important for thermodynamic evaluation, study of carbon capture readiness and economic analysis. A simplified dynamic model for the IGCC process is developed in this paper. In the IGCC process, Texaco gasifier is adopted and modelled based on chemical equilibriums principle which is used to predict the syngas content. The influences of the key input parameters such as oxygen/coal ratio and water/coal ratio to syngas generation are studied. The simulation results of the gasifier are validated comparing with the industry data provided by Lu-nan fertilizer factory. In addition, Water-shift reactor, gas turbine, and heat recovery steam generation modules are modeled to study the dynamic performance with respect to the variation from the input of syngas stream. The simulation results show the dynamic changes of key output variables, including gas temperature, power output and mole percentages of hydrogen, carbon dioxide in the syngas. The process dynamic responses with three types of coal inputs are studied in the paper and the results are presented to show the dynamic variation trend.

Study of a Pneumatic-electrical System for Exhaust Air Energy Recovery

Abstract: In comparison to hydraulic and electrical actuators, the significant drawback of pneumatic actuators is low energy conversion ability which is due to the open-circuit structure in nature. This paper represents a hybrid pneumatic-electrical system for the purpose of recycling exhaust compressed air energy from existing pneumatic actuator outlets to generate electricity. A proper control strategy is developed to manage the actuator system operation and to ensure the energy recovery work well. The pneumatic- electrical system mathematical model and the simulation results are presented. The laboratory experimental tests are described. The system energy efficiency is also analyzed. The simulated and experimental studies demonstrate that the whole system operated by the designed controller can successfully recover exhaust compressed air energy under appropriate working conditions.

Simulation study of energy efficiency for a hybrid wind turbine system

Abstract: Energy Storage is evidently seen as a world-wide focusing research topic in recent years both for the industrial and academic sectors. This paper presents the recent research progress on a new hybrid system by integrating a wind turbine operation with compressed air energy storage. A scroll air motor is employed as the key device of “air-electricity power transformer” to convert compressed air energy to driving power for direct compensation of the generator driving power reduction during the low wind speed period. A complete mathematical model for the whole hybrid system is developed, and the model based pneumatic energy efficiency analysis is conducted under different operation conditions. The simulation results are of reference and guidance to the feasibility study and demonstrated the great potential of this proposed system for industrial applications.

Dynamic matrix model predictive control of coal feeder speed of a supercritical power plant

Abstract: In this paper, a control strategy using Dynamic Matrix Control algorithm is proposed to enhance the already installed PID controller for the control of the coal flow delivered to the power plant boiler. The future control inputs are calculated by solving the quadratic optimization problem using Hildreth algorithm. Two cases are considered in testing and comparing the performance of the new DMC control strategy. The simulation results showed an improved control performance compared to the case of using the PID controller for mill dynamic responses.