A power distribution monitoring system is provided that can include a number of features. The system can include a plurality of power line sensing devices configured to attach to individual conductors on a power grid distribution network. In some embodiments, the power line sensors can include a split-core transformer. In some embodiments, a power line sensing device is disposed on each conductor of a three-phase network. The sensing devices can be configured to measure and monitor, among other things, current and electric-field on the conductors. Methods of installing, sealing, and protecting the split-core transformers of the power line sensors are also discussed.

Energy harvest split core design elements for ease of installation, high performance, and long term reliability

A power distribution monitoring system is provided that can include a number of features. The system can include a plurality of monitoring devices configured to attach to individual conductors on a power grid distribution network. In some embodiments, a monitoring device is disposed on each conductor of a three-phase network and utilizes a split-core transformer to harvest energy from the conductors. The monitoring devices can be configured to harvest energy from the AC power grid and apply a DC bias to core halves of the split-core transformer to maintain a positive magnetic force between the core halves. Methods of installing and using the monitoring devices are also provided.

Distribution Line Clamp Force Using DC Bias on Coil

A novel observation method is proposed to study the streamer-leader propagation processes of long air-gap positive discharges. Experiments of 3-12 m air-gap discharges have been conducted in this paper. The observed images could clearly and particularly describe the characteristics of the positive streamer-leader propagation processes. Some important phenomena of the propagation processes are indicated and discussed, such as the leader's velocity that varied with the time, the different lengths of inception leaders, the leader's branching phenomena, the continuous streamer-leader propagation processes simultaneously with the voltage's descent, and the upward leader's propagation processes.

Observation of the Streamer–Leader Propagation Processes of Long Air-Gap Positive Discharges

Power system secondary ac arcs are plasma discharges in free space with dimensions in meters. The motion of secondary arcs was investigated experimentally using high-speed video on a 1-m scale with a 3-MVA source. The measurements that were evaluated imposed forces, including wind, effects of the arc root, as well as early-stage horizontal and late-stage vertical movement. Partial short circuits of the arc column were observed. The arc column elongated with the de-ionization effect being increased. The column approached a maximum length before the arc extinction. An arc chain model was applied to establish the governing velocity equation. Based on the proposed model, simulations agreed well with the physical experiments.

Characteristics of Secondary AC Arc Column Motion Near Power Transmission-Line Insulator String

Large-scale integration of new renewables requires substantial increases of transmission capacity on existing transmission corridors. To limit land use, overhead transmission lines have been widely built as multicircuit lines. On these, changing one ac circuit to dc to increase transmission capacity leads to lines with hybrid ac/dc towers. Since practically no operational experience with such hybrid lines exists to date, questions such as superimposed ac and dc fields intensified by corona-generated space charges arise. In this paper, a method to simulate these ion-flow fields using the discontinuous Galerkin method is for the first time applied to hybrid towers. Ways to considerably reduce the computational effort of the problem are discussed. The results indicate that hybrid lines are feasible in reference to space-charge-related problems. Shielding the ground is possible at the expense of increased coupling between the ac and dc circuits.

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Ion-Flow Field Calculations of AC/DC Hybrid Transmission Lines

This paper proposes a semi-analytic finite element method to treat the open boundary axisymmetric electrostatic field problems. The method is applied to computing the potential distribution of the high voltage porcelain metal oxide arrester (MOA). The numerical example shows a good agreement between the calculated and measured results.

Calculation of the potential distribution of high voltage metal oxide arrester by using an improved semi-analytic finite element method

The breakage of overhead covered conductors on distribution lines resulting from the short-circuit arcs caused by lightning flash becomes a challenge as the application of covered conductors increases on distribution lines. Based on various methodologies and devices developed to avoid the covered conductor breakage in the world, novel arc-guided devices, including arcing protection hardware with barbs, clamping post composite insulator, and barb electrode clamping post porcelain/composite insulator are presented in this paper. Experimental results are also presented to validate these new developed devices. Devices based on the developed technologies have been widely applied on the power grids in China successfully.

Development of Arc-Guided Protection Devices Against Lightning Breakage of Covered Conductors on Distribution Lines

The electric fields under high-voltage direct current (HVdc) transmission lines and the ions produced by corona affect each other greatly. This paper presents an iterative method to calculate ion flow fields under HVdc bipolar transmission lines in the presence of wind. Both the electric fields and the ion densities are calculated by integral equation method. The method is fast and stable. The results are in good agreement with the experimental data. The ion flow fields under a plusmn 800-kV bipolar direct current (dc) transmission line are analyzed

Calculation of Ion Flow Field under HVDC Bipolar Transmission Lines by Integral Equation Method

This paper presents the study of a long electric arc in free air due to lightning stroke on the parallel gap lightning protection device (PGLPD) on high-voltage overhead transmission lines. Based on the latest electric arc model, the analysis method of the magnetic field generated by the current flowing through the PGLPD, electric arc, transmission lines, steel tower, and ground wires is developed, and the movement process of the long arc along the surface of the insulator strings is simulated. The simulation results are in agreement with the experimental results. The study is very helpful for the optimal design and suitable assemblage of the PGLPD

Movement simulation of long electric arc along the surface of insulator string in free air

Experiments on the motion of long alternating current arcs in atmospheric air show that the anode and cathode arc roots have different motion characteristics because of different formation mechanisms. During a half cycle of the arc current, the anode arc root moves towards the direction of magnetic force and occasionally has a jumping motion, while the cathode arc root moves sufficiently slow to consider it stationary and hardly has any jump. The arc column has a complex shape and moves under the drive of the magnetic force and is also quickened by the lower arc root.

Shanqiang Gu

Papers

Calculation of the potential distribution of high voltage metal oxide arrester by using an improved semi-analytic finite element method

Development of Arc-Guided Protection Devices Against Lightning Breakage of Covered Conductors on Distribution Lines

Calculation of Ion Flow Field under HVDC Bipolar Transmission Lines by Integral Equation Method

Movement simulation of long electric arc along the surface of insulator string in free air

Motion characteristics of long ac arcs in atmospheric air