Applied Mechanics and Materials Vols. 336-338

Abstract: Planning of combined cooling, heating and power (CCHP) systems are complicated due to the diversity of energy demands. Some mathematical models for the design of CCHP systems have been developed, most of which adopt a one-third peak load strategy. In this paper, we present a novel optimal planning method for CCHP systems, which is divided into two levels, the system level and the equipment level, each of which has a mathematical model. Minimizing the total annual cost is the optimal object of the system level, while minimizing system life-cycle cost is the optimal object of equipment level. Results show that the CCHP system planned by the novel optimal planning method can achieve better economy and energy efficiency, and the running costs are pretty lower.

Abstract: This paper proposes an improved algorithm for tracking the Thévenin equivalent parameters with local phasor measurements for voltage stability analysis. Estimation errors between the Thévenin equivalent voltage and impedance are mathematically formulated, and then used to correct the equivalent parameters with two subsequent measurements. This algorithm does not introduce any parameters drift problems and does not need a large data window to converge. A 2-bus test system, the IEEE 14-buses system and an actual 500kV grid system from China are used to test the proposed algorithm. Test results indicate that this algorithm is accurate, robust and fast for real time voltage stability monitoring and control.

Abstract: This paper proposes a novel technique for the new excitation control of the doubly-fed induction generator (DFIG) on power-station which connected to the grid. That is using the similar signals from rotor of a small capacity doubly-fed induction machine (DFIM) as a base to generate the control signals for the former DFIG. Based on this method, a simple but effective controller is designed, which ensures to decouple the active and reactive power supplied to the grid by using two separate parameters Kp and Kq. The advantage of this method is that it is simple but still effective.

Abstract: This paper introduced a voltage follower type of supply hybridized by the switch filter unit with the linear unit, analyzed the principle of the composing, the topology of Switch Linearity Hybrid (SLH) power converter. Theory analyses, simulation and experimental results showed that the SLH power converter possess the character of high efficiency, low THD, the capacity suitable to varied kinds of loads (including non-linear load) and resisting load disturbance.

Abstract: With the scale of integration of wind power increases gradually, the voltage stability and the fluctuation problem of the system caused by integration have become more and more prominent. Traditional AC power transmission mode cannot alleviate the adverse effects of integration of wind power, Flexible DC power transmission has many advantages due to the use of voltage source converters self-commutated characteristics, Flexible DC power provides a new technical method and also provides a solution for the integration. This paper introduces the basic structure and the basic control principle of Flexible DC power transmission technology. Then, through comparing the transient stability level and voltage supporting ability of AC power transmission with that of Flexible DC power transmission, an isolated system is used as an example to elaborate the beneficial contribution that the new integration of wind power make to the voltage stability, which indicates that Flexible DC power transmission technology has broad application prospect in the transmission area of wind power, and gives very good reference value for the Flexible DC power used in integration in the future.

Abstract: In the industrial world the interest in Precision Positioning Systems is exponentially increasing in relation to the rapid growth of Ultra High Precision (UHP) machining. A greater attention is given to traditional techniques and developing of innovative solutions. This paper intends to present a review of the actual state of art in precision positioning system based on flexure hinge related to industrial machines, showing a comparison between different techniques.

Abstract: The frequency characteristics of islanding operation are introduced firstly. The magnitude of balance between electromagnetic power and the original motive power and the inertia of the system are the critical factors that affect the frequency. Based on the possible over-frequency problems during the isolated operation of the regional network, the configuration principles of over frequency generator tripping are proposed. Taking an actual grid as an example, an adaptable and efficient configuration solution of over frequency generator tripping is made according to the principles. In addition, the coordination between over frequency generator tripping and over-speed protection controller is studied. This paper brings forward meaningful reference configuration principles for over frequency generator tripping that is suitable to small-capacity regional power grid which is in infirm interconnections.

Abstract: The dynamic modeling and simulation of a novel wall-climbing robot is presented. For the novel biped-wheel hybrid locomotion mechanism of the robot, its locomotion modes and typical state of motion are analyzed. Based on the description of the robots pose, the dynamic model for two typical states of motion, point turning in a flat surface and transition between two intersecting surfaces, is established. The equation for calculating adhesion force when the robot moves on arbitrary inclined surfaces is derived from the dynamic model. Simulations for the adhesion force are implemented with three typical examples. The results show that the tilt angle of the attachment surface and the motion direction of the robot have great influence on the adhesion force.

Abstract: Aiming at the problem of switching power supply stable output, a push-pull switching power supply was designed. the switching frequency is 100kHZ and the output voltage is 5V. System model of the push-pull switching power supply is established on PSpice, and research on the output performance of the push-pull switching power supply. By the parameter sweep analysis of load, the push-pull switching power supply can stabilize output in full load and light load conditions, and load regulation rate comply with the design requirements.

Abstract: With the rolling development of Suqiao-Wenan Oilfield, the original small treatment station-Station Wen 11, cannot satisfy production requirements. It is necessary to reform and expand the crude oil storage and treatment capacity, water-injection capability and natural gas treatment capacity, on the basis of the original construction; establish new crude oil treatment, fire-fighting and heating systems, as well as supporting systems like crude oil loading and unloading, automatic monitoring and cathodic protection systems, to form a medium-sized centralized oil-gas-water treatment station with complete functions. This paper introduces design, implementation and application effect of the process automation system after Station Wen 11 undergoes reconstruction and expansion.