Jialun Yang

Type Synthesis of Parallel Mechanisms with the First Class GF Sets and Two-Dimensional Rotations

The novel design of parallel mechanisms plays a key role in the potential application of parallel mechanisms. In this paper, the type synthesis of parallel mechanisms with the first class GF sets and two- dimensional rotations is studied. The rule of two- dimensional rotations is given, which lays the theoretical foundation for the intersection operations of specific GF sets. Next, kinematic limbs with specific characteristics are designed according to the 2-D and 3-D axes movement theorems. Finally, several synthesized parallel mechanisms with the first class GF sets and two- dimensional rotations are illustrated to show the effectiveness of the proposed methodology.

Conceptual design of a novel de-icing device for power transmission lines

The technique regarding de-icing and anti-icing for power transmission lines is very important since severe ice storms may cause disaster to power grid due to influence of the accreted ice. In this paper, a novel de-icing device with fixed function position for power transmission lines is proposed. The possibility of mechanical de-icing methods and the features of fixed function position are given to show the advantages of the proposed de-icing device. In particular, the structure of the de-icing device and the function principle are described. The proposed de-icing device would enhance the customer service and benefit power companies and line maintenance companies.

Type synthesis of TMDs as anti-galloping devices for overhead transmission lines by using planar mechanisms

The successful application of anti-galloping devices plays an important role for the safe operation of power grids, including the application of torsional mass dampers (TMDs). In this paper, the performance index of types of TMDs is proposed based on the galloping mechanism of overhead transmission lines. Furthermore, the types of TMDs are synthesized, taking the performance index of the types of TMDs and operation experience of anti-galloping into account. The synthesized TMDs feature symmetrical or non-symmetrical structures. Finally, several TMDs are illustrated to show the effectiveness of the proposed methodology.

Impact on the Extreme Value of Ice Thickness of Conductors from Probability Distribution Models

Probability distribution model can affect the extreme value of standard ice thickness on conductors of transmission lines for different return periods. This paper discusses the impact of three probability distribution models on calculation of standard ice thickness, which are Pearson III distribution model (P-III), generalized extreme value distribution model (GEV), and generalized Pareto distribution model (GPD), respectively. The historic icing data have been collected in Lvcongpo Mountain from Hubei province, including icing data from north-south direction, west-east direction, bigger data from two directions, and smaller data from two directions. The analyzing results indicate that GPD is more suitable than P-III and GEV for the icing data collected from Lvcongpo Mountain, which is helpful to reasonably determine the design ice thickness of conductors of transmission lines.

Simulation of Anti-galloping Effects of Phase-to-Phase Spacers in Transmission Line

Currently, the application of phase-to-phase spacers can effectively prevent and control line faults caused by conductor galloping and is one of the most effective methods to prevent galloping of transmission lines. The installation layout scheme of phase-to-phase spacers directly affects the anti-galloping effect. Moreover, the common empirical formula can not accurately assess the anti-galloping effect of phase-to-phase spacers. In this paper, the nonlinear finite element method is employed to establish an accurate analysis model of phase-to-phase spacers for conductors. And the anti-galloping effects of phase-to-phase spacers installed in different ways are analyzed, with the aim of providing an effective method for the installation of phase-to-phase spacers used in practical transmission lines.

Method for the Development of Ice Thickness Distribution Maps for Power Transmission Infrastructures in China

AbstractThis technical note presents a method for the development of ice thickness distribution maps. It makes use of 0°C layer, stepwise regression, and operational experiences to address such problems as a lack of icing data. Using the proposed method, ice thickness distribution maps can estimate the accreted atmospheric ice for power transmission infrastructures in a more reasonable and accurate manner.