Advanced Materials Research Vols. 694-697

Abstract: This paper presents an optimization method for distribution network voltage deviation control measures based on life cycle cost (LCC) theory. The overall process of this method had been introduced, and the LCC decomposition model of distribution network reconstruction had been analyzed in details. The existing statistical data were used to build the LCC cost models for changing the cross section of the conductor, reactive power compensation and adjusting the transformer tap. Finally, a 10kV feeder was taken as an example to illustrate the application of the proposed method, it included the voltage deviation estimation, voltage improvement plan development and plan optimization based on LCC theory. The method proposed in this paper can be used to improve scientificalness and economical efficiency in planning distribution network voltage deviation control measures by power supply department.

Abstract: In order to obtain the distribution law of electric field and the insulation performance of the insulators in ZF32-126 isolated ground module gas chamber, the three-dimensional electrostatic field of gas chamber was calculated and analyzed by using finite element software. The field strength focal point and the maximum field strength inside the gas chamber field can be obtained from the analysis of the electric field. Then the breakdown field strength of ZF32-126 isolated ground module was calculated according to the engineering practice limit formula. Thus the insulation properties of the isolated ground module can be determined by the breakdown field strength, and it can provide a theoretical basis and recommendations for the optimization of the internal structure of GIS device.

Abstract: A new theory of leakage protection was presented for the low-voltage power system. The corresponding circuit model was established, then the operational principle was analyzed and the experiment was researched in this paper. The results showed: when the single-phase leakage occurred, the leakage current will be greatly reduced before the protective system shut off the power source. And the power source cannot shut off immediately in the good isolation, which can keep the important load operating normally. At the same time, the protective system can detect the useful signal, which can warn immediately.

Abstract: This Paper Briefly Describes the Basic Principle of Reactive Power Compensation and Introduces the Indirect Current Control and Direct Current Control Method Based on Instantaneous Reactive Power Theory. Compare the Two Control Theory and Use the MATABLE Simulink Environment to Analyzing the Difference between the Two Methods

Abstract: UPFC is considered as an important modern device in the flexible ac transmission systems family that provides the controllability and flexibility for transmission lines. It is also capable of enhancing the stability of the power system by the addition of a supplementary damping controller, which can be installed on any control channel of the UPFC inputs to implement the task of power oscillation damping controller. This paper presents the application of UPFC to enhance damping of low frequency oscillations by the simultaneous coordinated design between power system stabilizer and different UPFC supplementary damping controller in order to identify the design that provided the most robust damping performance in a single machine infinite bus. The parameters of the damping controller were tuned in the individual and coordinated design by using a chaotic particle swarm optimization algorithm that optimized the given eigenvalue-based objective function. The results analysis reveals that the proposed coordinated designs have high ability in damping Low-frequency oscillations and improve the system damping over their individual control responses. In addition, the coordinated design PSS & δE provides superior performance in comparison to the all coordinated designs.

Abstract: In order to solve the problems which are caused by wind power and solar power on-grid, such as power quality, stability, reliability and so on, this paper proposes wind and solar micro-grid including energy storage system(ESS). The micro-grid uses two buses: AC bus and DC bus. Micro-source current is connected to the grid with the same inverter, which can reduce the micro-grid control difficulties. The energy storage system connected to the grid through the inverter could directly absorb energy from the grid. The DC side of the energy storage system using bidirectional DC / DC converter, which can keep the DC side of the battery storage stable.

Abstract: Switched reluctance motor (SRM) has the characteristic of fault tolerance inherently. Short-circuit in motors windings and the power converter are ones of the most common faults. Based on finite element analysis software Maxwell and circuit analysis software Simplorer, this paper takes an in-depth look at the principle of short-circuit fault, and two cases are simulated, one where a few turns are shorted, and one where a complete pole is shorted, and analysis the effect of main faults on SRD performances based on asymmetric half-bridge power converter, respectively from the view of magnetic circuit and field circuit. Results of simulation show that these failures have exert some negative effects on parameters of current and torque of the entire system.

Abstract: This paper mainly studies wind power fluctuations how to affect voltage stability after the wind power grid integration, and reactive power compensation equipment on improving effect. In certain parts of the wind farm, for example, firstly, analyzing the wind farm reactive power problems. Then introduce the reactive power compensation equipment that used in the wind farm. Finally, with PSCAD software, making a simulation analysis about the influence on the power grid voltage according to adopting the different reactive power compensation devices or not.

Abstract: Generallythe critical distance stress theory was applied for the fatigue limitestimation of general structures. In thismethod, it needs only two parameters, fatiguelimit of smooth specimen (σ_w0), and threshold stress intensityfactor range (∆K_th). In this paper we extended this method for theestimation of low cycle fatigue lifetoo. In this improvement wedefine the critical distance (r_c’) on static strength conditions,which is calculated using ultimate tensile strength (σ_B) andfracture toughness (K_IC), in addition to the critical distance onfatigue limit condition (r_c). Then the critical distances of any lowcycle fatigue conditions can be calculated by interpolation of criticaldistance on fatigue limit (r_c) with critical distance on staticstrength (r_c’). By unifying these low cycle fatigue life estimationmethod with high cycle fatigue limit estimation method we can estimate the fullrange fatigue life easily. And to confirm the availabilityof this estimation method we perform the fatigue test for circlehole specimens, sharp V notch specimens andfretting fatigue specimens.

Abstract: In this paper, the ball mills supported with double sliding shoes and the edge-transmission are compared. The mechanical model of ball mill supported with the double sliding shoes is established. The shearing force diagram, bending moment diagram and torque diagram are been carried out with the alteration of the double sliding shoes. After the support position improved, the felicitous rotator thickness is calculated based on the Third Strength Theory. It is showed by the calculation result; the rotator in manufacturing according to the experience is too thick. The thickness of the ball mill can be reduced. Then the weight of the ball mill can be reduced too. The light weighting design theoretical basis for large equipment is provided.