A Hybrid Diagnosis Method for Inverter Open-circuit Faults in PMSM Drives

In order to improve the evaluation process of inverter open-circuit faults diagnosis in permanent magnet synchronous motor(PMSM)drives,this paper presents a diagnosis method based on current residuals and machine learning models.The machine learning models are introduced to make a comprehensive evaluation for the current residuals obtained from a state observer,instead of evaluating the residuals by comparing with thresholds.Meanwhile,fault diagnosis and location are conducted simultaneously by the machine learning models,which simplifies the diagnosis process.Besides,a sampling strategy is designed to implement the proposed scheme online.Experiments are carried out on a DSP based PMSM drive,and the effectiveness of the proposed method is verified.

Surface currents measured by GPS drifters in Daya Bay and along the eastern Guangdong coast

GPS-based surface drifters were used to investigate the surface currents in Daya Bay and along the eastern Guangdong coast in China.Surface current vectors were measured based on the GPS location and corresponding time information sent by drifters through the mobile phone network.The analysis of data from 120 drifters,deployed in late spring 2018 in the case-study region,shows that the drifters are generally capable of capturing the surface(tidal and residual)currents.The drifter trajectories suggest an anticlockwise surface current inside Daya Bay and a north-eastward current along the eastern Guangdong coast,where the coastal current along the eastern Guangdong coast is faster than that inside Daya Bay.The surface currents in the investigated region follow an irregular semidiurnal cycle due to the influence of the tidal current,while the currents inside Daya Bay are strongly affected by the topography.According to the harmonic analysis,an irregular semidiurnal type of tidal current is evident at a study grid inside Daya Bay,with an Eulerian residual current speed of 9.0 cm/s and a direction of 276°.The Lagrangian residual current outside Daya Bay moves north-eastward with a mean speed of 22 cm/s along the eastern Guangdong coast,while the current inside Daya Bay moves northward to the bay head with a mean speed of about 8.0 cm/s,which agrees well with the one reported in other literatures.

Single-phase-to-ground Fault Detection with Distributed Parameters Analysis in Non-direct Grounded Systems

The fast and accurate detection of the single-phaseto-ground fault is of great significance for the reliability and safety of the power supply.In this paper,novel algorithms for distribution network protection were proposed with distributed parameters analysis in non-direct grounded systems.At first,novel generating mechanisms of zero-sequence voltage and residual current were proposed.Then the compositions of residue parameters,including residual current and residual admittances,were decomposed in detail.After that,an improved algorithm for a fault resistance calculation of a single phase-to-earth fault was also proposed,and the algorithm is much more convenient as it only needs to measure the variation of the zero-sequence voltage and does not need the prerequisites of the faulty feeder selection.Furthermore,the fault feeder can also be selected by an improved calculation algorithm of zero-sequence admittance of the faulty feeder,which cannot be affected by the asymmetry of the network.Theoretical analysis and the MATALB/Simulink simulation results demonstrate the effectiveness of the proposed algorithms.