A Method of Single-terminal MMC Single-pole Grounding Protection for DC Distribution Network Based on Multi-class Similarity Analysis

Based on the analysis model of single-pole to ground fault occurred in single-ended MMC DC distribution network, the characteristics of single-pole to ground fault are studied. The similarity of positive and negative current between the fault feeder and the non-fault feeder, the similarity of fault current between the fault feeder and the non-fault feeder, and the similarity of positive and negative current sum between the two feeders are analyzed. Based on the differences among the three types of similarity, a new method of single-pole grounding protection for DC distribution network with MMC based on multi-type similarity analysis is proposed. The simulation results show that this method can accurately determine the fault feeder, and has the characteristics of strong anti-interference ability, simple calculation and easy implementation. It can effectively solve the problem of single-pole grounding protection of DC distribution network and effectively improve the safety and reliability of power supply of DC distribution network.

CN Tower current wavefront parameters

This work is focused on the establishment of comprehensive statistics concerning the characteristics of the lightning current measured at the CN Tower during five years (1992-1996). Negative lightning currents are characterized with two distinguished impulses: short risetimes’ impulses, and impulses with substantially larger risetimes and larger current peaks in comparison with fast impulses. The slower negative current impulses were found to occur either in single stroke flashes or as first strokes in multiple stroke flashes, suggesting that they may belong to downward-initiated lightning to the CN Tower. The statistical analysis illustrates that there is a substantial difference in current wavefront parameter of ordinary negative fast wavefront impulses and those for slow wavefront negative impulses. The obtained statistics are very important for building lightning protection means against direct strikes to power lines, substation and communication equipments, as well as against lightning occurring in their vicinities.

Tunable photocurrent switching behavior of ZnO/Cu2O heterojunction photodetector to realize bipolar binary photoresponse

The tunable bipolar binary photoresponse characteristics (positive and negative current value changes) of the heterojunction photodetectors (PDs) is used to realize applications of optical communications, optical information storage, and multiple...

Preparation and electrochemical properties of a novel porous Ti/Sn–Sb-RuOx/β-PbO2/MnO2 anode for zinc electrowinning

PbO2 electrodes exhibit symmetry on the CV curve in MnSO4 bath (oxidation peak occurs at 1.00–1.40 V) and asymmetry in Mn(NO3)2 plating solution (negative current value at 1.00–1.18 V). The current rapidly rises to a large peak current at 1.25 V.

Bistable permanent magnet actuator based on double wing magnetic flux

This letter presents a bistable permanent magnet actuator, based on double wing magnetic fluxes (DWMF) formed by the structure of welding sleeve and slotted armature. The double wing magnetic fluxes consist of high wing magnetic flux (HWMF) and low wing magnetic flux (LWMF), resulting in bistable performance under differentiating control. Parameters improvement around DWMF is analyzed based on modeling, and optimized results for a prototype actuator are obtained. The experimental and simulation results agree well, and show that the prototype actuator can realize bistable performance under the DC step voltage drive, with the holding force of 8.2 N (without current) and the restoring force of −31.7 N (with negative current), the dynamic results show that the displacement response time within 8 mm is 28 ms, of which the actuation time is 16.5 ms, the transient maximum power consumption of the restoring period is 18 W.